diff --git a/Edgware.SR6/configprops.groovy b/Edgware.SR6/configprops.groovy new file mode 100644 index 00000000..5c9bebdd --- /dev/null +++ b/Edgware.SR6/configprops.groovy @@ -0,0 +1,74 @@ +/** + * Run this file with groovy and collect the result as an asciidoctor source file: + * 
+ * $ groovy configprops.groovy | egrep -v PathMatchingResourcePatternResolver | tee configprops.adoc
+ *
+ */ + +@GrabResolver(name='milestone', root='http://repo.spring.io/milestone/') +@Grab('org.codehaus.groovy:groovy-json:2.5.0') +@Grab('org.codehaus.groovy:groovy-nio:2.5.0') +@Grab('org.codehaus.groovy:groovy-xml:2.5.0') +@Grab('org.springframework.cloud:spring-cloud-stream:1.3.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-bus-amqp:1.3.5.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-config:1.4.7.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-config-server:1.4.7.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-netflix-eureka-server:1.4.7.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-netflix-eureka-client:1.4.7.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-aws:1.2.4.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-security:1.2.4.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-consul-all:1.3.6.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-zookeeper-all:1.2.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-sleuth:1.3.6.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-starter-cloudfoundry:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-cloudfoundry-discovery:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-contract-stub-runner:1.2.7.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-vault-config:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-vault-config-aws:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-vault-config-databases:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-vault-config-consul:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-vault-config-rabbitmq:1.1.3.RELEASE') +@Grab('org.springframework.cloud:spring-cloud-gateway-mvc:1.0.3.RELEASE') + +import org.springframework.core.io.support.PathMatchingResourcePatternResolver +import org.springframework.core.io.Resource +import groovy.json.JsonSlurper + +def resources = new PathMatchingResourcePatternResolver().getResources("classpath*:/META-INF/spring-configuration-metadata.json") + +TreeSet names = new TreeSet() +def descriptions = [:] +resources.each { it -> + if (it.url.toString().contains("cloud")) { + def slurper = new JsonSlurper() + slurper.parseText(it.inputStream.text).properties.each { val -> + names.add val.name + descriptions[val.name] = new ConfigValue(val.name, val.description, val.defaultValue) + } + } +} +println "|===" +println "|Name | Default | Description" +println "" +names.each { it -> + println descriptions[it] + println "" +} +println "|===" + + +class ConfigValue { + String name + String description + Object defaultValue + ConfigValue(){} + ConfigValue(String name, String description, Object defaultValue) { + this.name = name + this.description = description + this.defaultValue = defaultValue + } + String toString() { + def value = defaultValue==null?'':"${defaultValue}" + "|${name} | ${value} | ${description?:''}" + } +} \ No newline at end of file diff --git a/Edgware.SR6/css/highlight.css b/Edgware.SR6/css/highlight.css new file mode 100644 index 00000000..ffefef72 --- /dev/null +++ b/Edgware.SR6/css/highlight.css @@ -0,0 +1,35 @@ +/* + code highlight CSS resemblign the Eclipse IDE default color schema + @author Costin Leau +*/ + +.hl-keyword { + color: #7F0055; + font-weight: bold; +} + +.hl-comment { + color: #3F5F5F; + font-style: italic; +} + +.hl-multiline-comment { + color: #3F5FBF; + font-style: italic; +} + +.hl-tag { + color: #3F7F7F; +} + +.hl-attribute { + color: #7F007F; +} + +.hl-value { + color: #2A00FF; +} + +.hl-string { + color: #2A00FF; +} \ No newline at end of file diff --git a/Edgware.SR6/css/manual-multipage.css b/Edgware.SR6/css/manual-multipage.css new file mode 100644 index 00000000..0c484531 --- /dev/null +++ b/Edgware.SR6/css/manual-multipage.css @@ -0,0 +1,9 @@ +@IMPORT url("manual.css"); + +body.firstpage { + background: url("../images/background.png") no-repeat center top; +} + +div.part h1 { + border-top: none; +} diff --git a/Edgware.SR6/css/manual-singlepage.css b/Edgware.SR6/css/manual-singlepage.css new file mode 100644 index 00000000..4a7fd140 --- /dev/null +++ b/Edgware.SR6/css/manual-singlepage.css @@ -0,0 +1,6 @@ +@IMPORT url("manual.css"); + +body { + background: url("../images/background.png") no-repeat center top; +} + diff --git a/Edgware.SR6/css/manual.css b/Edgware.SR6/css/manual.css new file mode 100644 index 00000000..0ecbe2e8 --- /dev/null +++ b/Edgware.SR6/css/manual.css @@ -0,0 +1,344 @@ +@IMPORT url("highlight.css"); + +html { + padding: 0pt; + margin: 0pt; +} + +body { + color: #333333; + margin: 15px 30px; + font-family: Helvetica, Arial, Freesans, Clean, Sans-serif; + line-height: 1.6; + -webkit-font-smoothing: antialiased; +} + +code { + font-size: 16px; + font-family: Consolas, "Liberation Mono", Courier, monospace; +} + +:not(a)>code { + color: #6D180B; +} + +:not(pre)>code { + background-color: #F2F2F2; + border: 1px solid #CCCCCC; + border-radius: 4px; + padding: 1px 3px 0; + text-shadow: none; + white-space: nowrap; +} + +body>*:first-child { + margin-top: 0 !important; +} + +div { + margin: 0pt; +} + +hr { + border: 1px solid #CCCCCC; + background: #CCCCCC; +} + +h1,h2,h3,h4,h5,h6 { + color: #000000; + cursor: text; + font-weight: bold; + margin: 30px 0 10px; + padding: 0; +} + +h1,h2,h3 { + margin: 40px 0 10px; +} + +h1 { + margin: 70px 0 30px; + padding-top: 20px; +} + +div.part h1 { + border-top: 1px dotted #CCCCCC; +} + +h1,h1 code { + font-size: 32px; +} + +h2,h2 code { + font-size: 24px; +} + +h3,h3 code { + font-size: 20px; +} + +h4,h1 code,h5,h5 code,h6,h6 code { + font-size: 18px; +} + +div.book,div.chapter,div.appendix,div.part,div.preface { + min-width: 300px; + max-width: 1200px; + margin: 0 auto; +} + +p.releaseinfo { + font-weight: bold; + margin-bottom: 40px; + margin-top: 40px; +} + +div.authorgroup { + line-height: 1; +} + +p.copyright { + line-height: 1; + margin-bottom: -5px; +} + +.legalnotice p { + font-style: italic; + font-size: 14px; + line-height: 1; +} + +div.titlepage+p,div.titlepage+p { + margin-top: 0; +} + +pre { + line-height: 1.0; + color: black; +} + +a { + color: #4183C4; + text-decoration: none; +} + +p { + margin: 15px 0; + text-align: left; +} + +ul,ol { + padding-left: 30px; +} + +li p { + margin: 0; +} + +div.table { + margin: 1em; + padding: 0.5em; + text-align: center; +} + +div.table table,div.informaltable table { + display: table; + width: 100%; +} + +div.table td { + padding-left: 7px; + padding-right: 7px; +} + +.sidebar { + line-height: 1.4; + padding: 0 20px; + background-color: #F8F8F8; + border: 1px solid #CCCCCC; + border-radius: 3px 3px 3px 3px; +} + +.sidebar p.title { + color: #6D180B; +} + +pre.programlisting,pre.screen { + font-size: 15px; + padding: 6px 10px; + background-color: #F8F8F8; + border: 1px solid #CCCCCC; + border-radius: 3px 3px 3px 3px; + clear: both; + overflow: auto; + line-height: 1.4; + font-family: Consolas, "Liberation Mono", Courier, monospace; +} + +table { + border-collapse: collapse; + border-spacing: 0; + border: 1px solid #DDDDDD !important; + border-radius: 4px !important; + border-collapse: separate !important; + line-height: 1.6; +} + +table thead { + background: #F5F5F5; +} + +table tr { + border: none; + border-bottom: none; +} + +table th { + font-weight: bold; +} + +table th,table td { + border: none !important; + padding: 6px 13px; +} + +table tr:nth-child(2n) { + background-color: #F8F8F8; +} + +td p { + margin: 0 0 15px 0; +} + +div.table-contents td p { + margin: 0; +} + +div.important *,div.note *,div.tip *,div.warning *,div.navheader *,div.navfooter *,div.calloutlist * + { + border: none !important; + background: none !important; + margin: 0; +} + +div.important p,div.note p,div.tip p,div.warning p { + color: #6F6F6F; + line-height: 1.6; +} + +div.important code,div.note code,div.tip code,div.warning code { + background-color: #F2F2F2 !important; + border: 1px solid #CCCCCC !important; + border-radius: 4px !important; + padding: 1px 3px 0 !important; + text-shadow: none !important; + white-space: nowrap !important; +} + +.note th,.tip th,.warning th { + display: none; +} + +.note tr:first-child td,.tip tr:first-child td,.warning tr:first-child td + { + border-right: 1px solid #CCCCCC !important; + padding-top: 10px; +} + +div.calloutlist p,div.calloutlist td { + padding: 0; + margin: 0; +} + +div.calloutlist>table>tbody>tr>td:first-child { + padding-left: 10px; + width: 30px !important; +} + +div.important,div.note,div.tip,div.warning { + margin-left: 0px !important; + margin-right: 20px !important; + margin-top: 20px; + margin-bottom: 20px; + padding-top: 10px; + padding-bottom: 10px; +} + +div.toc { + line-height: 1.2; +} + +dl,dt { + margin-top: 1px; + margin-bottom: 0; +} + +div.toc>dl>dt { + font-size: 32px; + font-weight: bold; + margin: 30px 0 10px 0; + display: block; +} + +div.toc>dl>dd>dl>dt { + font-size: 24px; + font-weight: bold; + margin: 20px 0 10px 0; + display: block; +} + +div.toc>dl>dd>dl>dd>dl>dt { + font-weight: bold; + font-size: 20px; + margin: 10px 0 0 0; +} + +tbody.footnotes * { + border: none !important; +} + +div.footnote p { + margin: 0; + line-height: 1; +} + +div.footnote p sup { + margin-right: 6px; + vertical-align: middle; +} + +div.navheader { + border-bottom: 1px solid #CCCCCC; +} + +div.navfooter { + border-top: 1px solid #CCCCCC; +} + +.title { + margin-left: -1em; + padding-left: 1em; +} + +.title>a { + position: absolute; + visibility: hidden; + display: block; + font-size: 0.85em; + margin-top: 0.05em; + margin-left: -1em; + vertical-align: text-top; + color: black; +} + +.title>a:before { + content: "\00A7"; +} + +.title:hover>a,.title>a:hover,.title:hover>a:hover { + visibility: visible; +} + +.title:focus>a,.title>a:focus,.title:focus>a:focus { + outline: 0; +} diff --git a/Edgware.SR6/ghpages.sh b/Edgware.SR6/ghpages.sh new file mode 100644 index 00000000..e0e69be3 --- /dev/null +++ b/Edgware.SR6/ghpages.sh @@ -0,0 +1,348 @@ +#!/bin/bash -x + +set -e + +# Set default props like MAVEN_PATH, ROOT_FOLDER etc. +function set_default_props() { + # The script should be executed from the root folder + ROOT_FOLDER=`pwd` + echo "Current folder is ${ROOT_FOLDER}" + + if [[ ! -e "${ROOT_FOLDER}/.git" ]]; then + echo "You're not in the root folder of the project!" + exit 1 + fi + + # Prop that will let commit the changes + COMMIT_CHANGES="no" + MAVEN_PATH=${MAVEN_PATH:-} + echo "Path to Maven is [${MAVEN_PATH}]" + REPO_NAME=${PWD##*/} + echo "Repo name is [${REPO_NAME}]" + SPRING_CLOUD_STATIC_REPO=${SPRING_CLOUD_STATIC_REPO:-git@github.com:spring-cloud/spring-cloud-static.git} + echo "Spring Cloud Static repo is [${SPRING_CLOUD_STATIC_REPO}" +} + +# Check if gh-pages exists and docs have been built +function check_if_anything_to_sync() { + git remote set-url --push origin `git config remote.origin.url | sed -e 's/^git:/https:/'` + + if ! (git remote set-branches --add origin gh-pages && git fetch -q) && [[ "${RELEASE_TRAIN}" != "yes" ]] ; then + echo "No gh-pages, so not syncing" + exit 0 + fi + + if ! [ -d docs/target/generated-docs ] && ! [ "${BUILD}" == "yes" ]; then + echo "No gh-pages sources in docs/target/generated-docs, so not syncing" + exit 0 + fi +} + +function retrieve_current_branch() { + # Code getting the name of the current branch. For master we want to publish as we did until now + # http://stackoverflow.com/questions/1593051/how-to-programmatically-determine-the-current-checked-out-git-branch + # If there is a branch already passed will reuse it - otherwise will try to find it + CURRENT_BRANCH=${BRANCH} + if [[ -z "${CURRENT_BRANCH}" ]] ; then + CURRENT_BRANCH=$(git symbolic-ref -q HEAD) + CURRENT_BRANCH=${CURRENT_BRANCH##refs/heads/} + CURRENT_BRANCH=${CURRENT_BRANCH:-HEAD} + fi + echo "Current branch is [${CURRENT_BRANCH}]" + git checkout ${CURRENT_BRANCH} || echo "Failed to check the branch... continuing with the script" +} + +# Switches to the provided value of the release version. We always prefix it with `v` +function switch_to_tag() { + if [[ "${RELEASE_TRAIN}" != "yes" ]] ; then + git checkout v${VERSION} + fi +} + +# Build the docs if switch is on +function build_docs_if_applicable() { + if [[ "${BUILD}" == "yes" ]] ; then + ./mvnw clean install -P docs -pl docs -DskipTests + fi +} + +# Get the name of the `docs.main` property +# Get whitelisted branches - assumes that a `docs` module is available under `docs` profile +function retrieve_doc_properties() { + MAIN_ADOC_VALUE=$("${MAVEN_PATH}"mvn -q \ + -Dexec.executable="echo" \ + -Dexec.args='${docs.main}' \ + org.codehaus.mojo:exec-maven-plugin:1.3.1:exec \ + -P docs \ + -pl docs) + echo "Extracted 'main.adoc' from Maven build [${MAIN_ADOC_VALUE}]" + + + WHITELIST_PROPERTY=${WHITELIST_PROPERTY:-"docs.whitelisted.branches"} + WHITELISTED_BRANCHES_VALUE=$("${MAVEN_PATH}"mvn -q \ + -Dexec.executable="echo" \ + -Dexec.args="\${${WHITELIST_PROPERTY}}" \ + org.codehaus.mojo:exec-maven-plugin:1.3.1:exec \ + -P docs \ + -pl docs) + echo "Extracted '${WHITELIST_PROPERTY}' from Maven build [${WHITELISTED_BRANCHES_VALUE}]" +} + +# Stash any outstanding changes +function stash_changes() { + git diff-index --quiet HEAD && dirty=$? || (echo "Failed to check if the current repo is dirty. Assuming that it is." && dirty="1") + if [ "$dirty" != "0" ]; then git stash; fi +} + +# Switch to gh-pages branch to sync it with current branch +function add_docs_from_target() { + local DESTINATION_REPO_FOLDER + if [[ -z "${DESTINATION}" && -z "${CLONE}" ]] ; then + DESTINATION_REPO_FOLDER=${ROOT_FOLDER} + elif [[ "${CLONE}" == "yes" ]]; then + mkdir -p ${ROOT_FOLDER}/target + local clonedStatic=${ROOT_FOLDER}/target/spring-cloud-static + if [[ ! -e "${clonedStatic}/.git" ]]; then + echo "Cloning Spring Cloud Static to target" + git clone ${SPRING_CLOUD_STATIC_REPO} ${clonedStatic} && cd ${clonedStatic} && git checkout gh-pages + else + echo "Spring Cloud Static already cloned - will pull changes" + cd ${clonedStatic} && git checkout gh-pages && git pull origin gh-pages + fi + if [[ -z "${RELEASE_TRAIN}" ]] ; then + DESTINATION_REPO_FOLDER=${clonedStatic}/${REPO_NAME} + else + DESTINATION_REPO_FOLDER=${clonedStatic} + fi + mkdir -p ${DESTINATION_REPO_FOLDER} + else + if [[ ! -e "${DESTINATION}/.git" ]]; then + echo "[${DESTINATION}] is not a git repository" + exit 1 + fi + if [[ -z "${RELEASE_TRAIN}" ]] ; then + DESTINATION_REPO_FOLDER=${DESTINATION}/${REPO_NAME} + else + DESTINATION_REPO_FOLDER=${DESTINATION} + fi + mkdir -p ${DESTINATION_REPO_FOLDER} + echo "Destination was provided [${DESTINATION}]" + fi + cd ${DESTINATION_REPO_FOLDER} + git checkout gh-pages + git pull origin gh-pages + + # Add git branches + ################################################################### + if [[ -z "${VERSION}" && -z "${RELEASE_TRAIN}" ]] ; then + copy_docs_for_current_version + else + copy_docs_for_provided_version + fi + commit_changes_if_applicable +} + + +# Copies the docs by using the retrieved properties from Maven build +function copy_docs_for_current_version() { + if [[ "${CURRENT_BRANCH}" == "master" ]] ; then + echo -e "Current branch is master - will copy the current docs only to the root folder" + for f in docs/target/generated-docs/*; do + file=${f#docs/target/generated-docs/*} + if ! git ls-files -i -o --exclude-standard --directory | grep -q ^$file$; then + # Not ignored... + cp -rf $f ${ROOT_FOLDER}/ + git add -A ${ROOT_FOLDER}/$file + fi + done + COMMIT_CHANGES="yes" + else + echo -e "Current branch is [${CURRENT_BRANCH}]" + # http://stackoverflow.com/questions/29300806/a-bash-script-to-check-if-a-string-is-present-in-a-comma-separated-list-of-strin + if [[ ",${WHITELISTED_BRANCHES_VALUE}," = *",${CURRENT_BRANCH},"* ]] ; then + mkdir -p ${ROOT_FOLDER}/${CURRENT_BRANCH} + echo -e "Branch [${CURRENT_BRANCH}] is whitelisted! Will copy the current docs to the [${CURRENT_BRANCH}] folder" + for f in docs/target/generated-docs/*; do + file=${f#docs/target/generated-docs/*} + if ! git ls-files -i -o --exclude-standard --directory | grep -q ^$file$; then + # Not ignored... + # We want users to access 1.0.0.RELEASE/ instead of 1.0.0.RELEASE/spring-cloud.sleuth.html + if [[ "${file}" == "${MAIN_ADOC_VALUE}.html" ]] ; then + # We don't want to copy the spring-cloud-sleuth.html + # we want it to be converted to index.html + cp -rf $f ${ROOT_FOLDER}/${CURRENT_BRANCH}/index.html + git add -A ${ROOT_FOLDER}/${CURRENT_BRANCH}/index.html + else + cp -rf $f ${ROOT_FOLDER}/${CURRENT_BRANCH} + git add -A ${ROOT_FOLDER}/${CURRENT_BRANCH}/$file + fi + fi + done + COMMIT_CHANGES="yes" + else + echo -e "Branch [${CURRENT_BRANCH}] is not on the white list! Check out the Maven [${WHITELIST_PROPERTY}] property in + [docs] module available under [docs] profile. Won't commit any changes to gh-pages for this branch." + fi + fi +} + +# Copies the docs by using the explicitly provided version +function copy_docs_for_provided_version() { + local FOLDER=${DESTINATION_REPO_FOLDER}/${VERSION} + mkdir -p ${FOLDER} + echo -e "Current tag is [v${VERSION}] Will copy the current docs to the [${FOLDER}] folder" + for f in ${ROOT_FOLDER}/docs/target/generated-docs/*; do + file=${f#${ROOT_FOLDER}/docs/target/generated-docs/*} + copy_docs_for_branch ${file} ${FOLDER} + done + COMMIT_CHANGES="yes" + CURRENT_BRANCH="v${VERSION}" +} + +# Copies the docs from target to the provided destination +# Params: +# $1 - file from target +# $2 - destination to which copy the files +function copy_docs_for_branch() { + local file=$1 + local destination=$2 + if ! git ls-files -i -o --exclude-standard --directory | grep -q ^${file}$; then + # Not ignored... + # We want users to access 1.0.0.RELEASE/ instead of 1.0.0.RELEASE/spring-cloud.sleuth.html + if [[ ("${file}" == "${MAIN_ADOC_VALUE}.html") || ("${file}" == "${REPO_NAME}.html") ]] ; then + # We don't want to copy the spring-cloud-sleuth.html + # we want it to be converted to index.html + cp -rf $f ${destination}/index.html + git add -A ${destination}/index.html + else + cp -rf $f ${destination} + git add -A ${destination}/$file + fi + fi +} + +function commit_changes_if_applicable() { + if [[ "${COMMIT_CHANGES}" == "yes" ]] ; then + COMMIT_SUCCESSFUL="no" + git commit -a -m "Sync docs from ${CURRENT_BRANCH} to gh-pages" && COMMIT_SUCCESSFUL="yes" || echo "Failed to commit changes" + + # Uncomment the following push if you want to auto push to + # the gh-pages branch whenever you commit to master locally. + # This is a little extreme. Use with care! + ################################################################### + if [[ "${COMMIT_SUCCESSFUL}" == "yes" ]] ; then + git push origin gh-pages + fi + fi +} + +# Switch back to the previous branch and exit block +function checkout_previous_branch() { + # If -version was provided we need to come back to root project + cd ${ROOT_FOLDER} + git checkout ${CURRENT_BRANCH} || echo "Failed to check the branch... continuing with the script" + if [ "$dirty" != "0" ]; then git stash pop; fi + exit 0 +} + +# Assert if properties have been properly passed +function assert_properties() { +echo "VERSION [${VERSION}], RELEASE_TRAIN [${RELEASE_TRAIN}], DESTINATION [${DESTINATION}], CLONE [${CLONE}]" +if [[ "${VERSION}" != "" && (-z "${DESTINATION}" && -z "${CLONE}") ]] ; then echo "Version was set but destination / clone was not!"; exit 1;fi +if [[ ("${DESTINATION}" != "" && "${CLONE}" != "") && -z "${VERSION}" ]] ; then echo "Destination / clone was set but version was not!"; exit 1;fi +if [[ "${DESTINATION}" != "" && "${CLONE}" == "yes" ]] ; then echo "Destination and clone was set. Pick one!"; exit 1;fi +if [[ "${RELEASE_TRAIN}" != "" && -z "${VERSION}" ]] ; then echo "Release train was set but no version was passed!"; exit 1;fi +} + +# Prints the usage +function print_usage() { +cat </` +- if the destination switch is passed (-d) then the script will check if the provided dir is a git repo and then will + switch to gh-pages of that repo and copy the generated docs to `docs//` +- if the release train switch is passed (-r) then the script will check if the provided dir is a git repo and then will + switch to gh-pages of that repo and copy the generated docs to `docs/` + +USAGE: + +You can use the following options: + +-v|--version - the script will apply the whole procedure for a particular library version +-r|--releasetrain - instead of nesting the docs under the project_name/version folder the docs will end up in version +-d|--destination - the root of destination folder where the docs should be copied. You have to use the full path. + E.g. point to spring-cloud-static folder. Can't be used with (-c) +-b|--build - will run the standard build process after checking out the branch +-c|--clone - will automatically clone the spring-cloud-static repo instead of providing the destination. + Obviously can't be used with (-d) + +EOF +} + + +# ========================================== +# ____ ____ _____ _____ _____ _______ +# / ____|/ ____| __ \|_ _| __ \__ __| +# | (___ | | | |__) | | | | |__) | | | +# \___ \| | | _ / | | | ___/ | | +# ____) | |____| | \ \ _| |_| | | | +# |_____/ \_____|_| \_\_____|_| |_| +# +# ========================================== + +while [[ $# > 0 ]] +do +key="$1" +case ${key} in + -v|--version) + VERSION="$2" + shift # past argument + ;; + -r|--releasetrain) + RELEASE_TRAIN="yes" + ;; + -d|--destination) + DESTINATION="$2" + shift # past argument + ;; + -b|--build) + BUILD="yes" + ;; + -c|--clone) + CLONE="yes" + ;; + -h|--help) + print_usage + exit 0 + ;; + *) + echo "Invalid option: [$1]" + print_usage + exit 1 + ;; +esac +shift # past argument or value +done + +assert_properties +set_default_props +check_if_anything_to_sync +if [[ -z "${VERSION}" ]] ; then + retrieve_current_branch +else + switch_to_tag +fi +build_docs_if_applicable +retrieve_doc_properties +stash_changes +add_docs_from_target +checkout_previous_branch diff --git a/Edgware.SR6/images/.gitkeep b/Edgware.SR6/images/.gitkeep new file mode 100644 index 00000000..e69de29b diff --git a/Edgware.SR6/images/Deps.png b/Edgware.SR6/images/Deps.png new file mode 100644 index 00000000..14268143 Binary files /dev/null and b/Edgware.SR6/images/Deps.png differ diff --git a/Edgware.SR6/images/Hystrix.png b/Edgware.SR6/images/Hystrix.png new file mode 100644 index 00000000..7d4e17ed Binary files /dev/null and b/Edgware.SR6/images/Hystrix.png differ diff --git a/Edgware.SR6/images/HystrixFallback.png b/Edgware.SR6/images/HystrixFallback.png new file mode 100644 index 00000000..372018c7 Binary files /dev/null and b/Edgware.SR6/images/HystrixFallback.png differ diff 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+
+
+
+

1.3.8.RELEASE

+
+
+
+
+

Pick The Documentation Option

+
+
+ +
+
+
+
+ + + + + \ No newline at end of file diff --git a/Edgware.SR6/multi/css/highlight.css b/Edgware.SR6/multi/css/highlight.css new file mode 100644 index 00000000..ffefef72 --- /dev/null +++ b/Edgware.SR6/multi/css/highlight.css @@ -0,0 +1,35 @@ +/* + code highlight CSS resemblign the Eclipse IDE default color schema + @author Costin Leau +*/ + +.hl-keyword { + color: #7F0055; + font-weight: bold; +} + +.hl-comment { + color: #3F5F5F; + font-style: italic; +} + +.hl-multiline-comment { + color: #3F5FBF; + font-style: italic; +} + +.hl-tag { + color: #3F7F7F; +} + +.hl-attribute { + color: #7F007F; +} + +.hl-value { + color: #2A00FF; +} + +.hl-string { + color: #2A00FF; +} \ No newline at end of file diff --git a/Edgware.SR6/multi/css/manual-multipage.css b/Edgware.SR6/multi/css/manual-multipage.css new file mode 100644 index 00000000..0c484531 --- /dev/null +++ b/Edgware.SR6/multi/css/manual-multipage.css @@ -0,0 +1,9 @@ +@IMPORT url("manual.css"); + +body.firstpage { + background: url("../images/background.png") no-repeat center top; +} + +div.part h1 { + border-top: none; +} diff --git a/Edgware.SR6/multi/css/manual-singlepage.css b/Edgware.SR6/multi/css/manual-singlepage.css new file mode 100644 index 00000000..4a7fd140 --- /dev/null +++ b/Edgware.SR6/multi/css/manual-singlepage.css @@ -0,0 +1,6 @@ +@IMPORT url("manual.css"); + +body { + background: url("../images/background.png") no-repeat center top; +} + diff --git a/Edgware.SR6/multi/css/manual.css b/Edgware.SR6/multi/css/manual.css new file mode 100644 index 00000000..0ecbe2e8 --- /dev/null +++ b/Edgware.SR6/multi/css/manual.css @@ -0,0 +1,344 @@ +@IMPORT url("highlight.css"); + +html { + padding: 0pt; + margin: 0pt; +} + +body { + color: #333333; + margin: 15px 30px; + font-family: Helvetica, Arial, Freesans, Clean, Sans-serif; + line-height: 1.6; + -webkit-font-smoothing: antialiased; +} + +code { + font-size: 16px; + font-family: Consolas, "Liberation Mono", Courier, monospace; +} + +:not(a)>code { + color: #6D180B; +} + +:not(pre)>code { + background-color: #F2F2F2; + border: 1px solid #CCCCCC; + border-radius: 4px; + padding: 1px 3px 0; + text-shadow: none; + white-space: nowrap; +} + +body>*:first-child { + margin-top: 0 !important; +} + +div { + margin: 0pt; +} + +hr { + border: 1px solid #CCCCCC; + background: #CCCCCC; +} + +h1,h2,h3,h4,h5,h6 { + color: #000000; + cursor: text; + font-weight: bold; + margin: 30px 0 10px; + padding: 0; +} + +h1,h2,h3 { + margin: 40px 0 10px; +} + +h1 { + margin: 70px 0 30px; + padding-top: 20px; +} + +div.part h1 { + border-top: 1px dotted #CCCCCC; +} + +h1,h1 code { + font-size: 32px; +} + +h2,h2 code { + font-size: 24px; +} + +h3,h3 code { + font-size: 20px; +} + +h4,h1 code,h5,h5 code,h6,h6 code { + font-size: 18px; +} + +div.book,div.chapter,div.appendix,div.part,div.preface { + min-width: 300px; + max-width: 1200px; + margin: 0 auto; +} + +p.releaseinfo { + font-weight: bold; + margin-bottom: 40px; + margin-top: 40px; +} + +div.authorgroup { + line-height: 1; +} + +p.copyright { + line-height: 1; + margin-bottom: -5px; 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+ font-size: 20px; + margin: 10px 0 0 0; +} + +tbody.footnotes * { + border: none !important; +} + +div.footnote p { + margin: 0; + line-height: 1; +} + +div.footnote p sup { + margin-right: 6px; + vertical-align: middle; +} + +div.navheader { + border-bottom: 1px solid #CCCCCC; +} + +div.navfooter { + border-top: 1px solid #CCCCCC; +} + +.title { + margin-left: -1em; + padding-left: 1em; +} + +.title>a { + position: absolute; + visibility: hidden; + display: block; + font-size: 0.85em; + margin-top: 0.05em; + margin-left: -1em; + vertical-align: text-top; + color: black; +} + +.title>a:before { + content: "\00A7"; +} + +.title:hover>a,.title>a:hover,.title:hover>a:hover { + visibility: visible; +} + +.title:focus>a,.title>a:focus,.title:focus>a:focus { + outline: 0; +} diff --git a/Edgware.SR6/multi/images/background.png b/Edgware.SR6/multi/images/background.png new file mode 100644 index 00000000..15dca6fb Binary files /dev/null and b/Edgware.SR6/multi/images/background.png differ diff --git a/Edgware.SR6/multi/images/caution.png b/Edgware.SR6/multi/images/caution.png new file mode 100644 index 00000000..8a5e4fca Binary files /dev/null and b/Edgware.SR6/multi/images/caution.png differ diff --git a/Edgware.SR6/multi/images/important.png b/Edgware.SR6/multi/images/important.png new file mode 100644 index 00000000..ec54df65 Binary files /dev/null and b/Edgware.SR6/multi/images/important.png differ diff --git a/Edgware.SR6/multi/images/logo.png b/Edgware.SR6/multi/images/logo.png new file mode 100644 index 00000000..ade2ce6e Binary files /dev/null and b/Edgware.SR6/multi/images/logo.png differ diff --git a/Edgware.SR6/multi/images/note.png b/Edgware.SR6/multi/images/note.png new file mode 100644 index 00000000..88d997b1 Binary files /dev/null and b/Edgware.SR6/multi/images/note.png differ diff --git a/Edgware.SR6/multi/images/sts_exception.png b/Edgware.SR6/multi/images/sts_exception.png new file mode 100644 index 00000000..8607c38a Binary files /dev/null and b/Edgware.SR6/multi/images/sts_exception.png differ diff --git a/Edgware.SR6/multi/images/tip.png b/Edgware.SR6/multi/images/tip.png new file mode 100644 index 00000000..6530abb4 Binary files /dev/null and b/Edgware.SR6/multi/images/tip.png differ diff --git a/Edgware.SR6/multi/images/warning.png b/Edgware.SR6/multi/images/warning.png new file mode 100644 index 00000000..0d5b5244 Binary files /dev/null and b/Edgware.SR6/multi/images/warning.png differ diff --git a/Edgware.SR6/multi/images/web-selected.png b/Edgware.SR6/multi/images/web-selected.png new file mode 100644 index 00000000..aa6b2da6 Binary files /dev/null and b/Edgware.SR6/multi/images/web-selected.png differ diff --git a/Edgware.SR6/multi/multi__additional_resources.html b/Edgware.SR6/multi/multi__additional_resources.html new file mode 100644 index 00000000..e059ecd6 --- /dev/null +++ b/Edgware.SR6/multi/multi__additional_resources.html @@ -0,0 +1,3 @@ + + + 47. Additional resources
47. Additional resources
Prev Part VII. Spring Cloud Sleuth Next

47. Additional resources

Marcin Grzejszczak talking about Spring Cloud Sleuth and Zipkin

click here to see the video

Prev Up Next
46. Introduction Home 48. Features
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41. Addressing all instances of a service
Prev Part VI. Spring Cloud Bus Next

41. Addressing all instances of a service

The "destination" parameter is used in a Spring PathMatcher (with the path separator as a colon :) to determine if an instance will process the message. Using the example from above, "/bus/refresh?destination=customers:**" will target all instances of the "customers" service regardless of the profiles and ports set as the ApplicationContext ID.

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40. Addressing an Instance Home 42. Application Context ID must be unique
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40. Addressing an Instance
Prev Part VI. Spring Cloud Bus Next

40. Addressing an Instance

The HTTP endpoints accept a "destination" parameter, e.g. "/bus/refresh?destination=customers:9000", where the destination is an ApplicationContext ID. If the ID is owned by an instance on the Bus then it will process the message and all other instances will ignore it. Spring Boot sets the ID for you in the ContextIdApplicationContextInitializer to a combination of the spring.application.name, active profiles and server.port by default.

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39. Quick Start Home 41. Addressing all instances of a service
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37. Apache Kafka Binder
Prev Part V. Binder Implementations Next

37. Apache Kafka Binder

37.1 Usage

For using the Apache Kafka binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-kafka</artifactId>
+</dependency>

Alternatively, you can also use the Spring Cloud Stream Kafka Starter.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-starter-stream-kafka</artifactId>
+</dependency>

37.2 Apache Kafka Binder Overview

A simplified diagram of how the Apache Kafka binder operates can be seen below.

Figure 37.1. Kafka Binder

kafka binder

The Apache Kafka Binder implementation maps each destination to an Apache Kafka topic. +The consumer group maps directly to the same Apache Kafka concept. +Partitioning also maps directly to Apache Kafka partitions as well.

37.3 Configuration Options

This section contains the configuration options used by the Apache Kafka binder.

For common configuration options and properties pertaining to binder, refer to the core documentation.

37.3.1 Kafka Binder Properties

spring.cloud.stream.kafka.binder.brokers

A list of brokers to which the Kafka binder will connect.

Default: localhost.

spring.cloud.stream.kafka.binder.defaultBrokerPort

brokers allows hosts specified with or without port information (e.g., host1,host2:port2). +This sets the default port when no port is configured in the broker list.

Default: 9092.

spring.cloud.stream.kafka.binder.zkNodes

A list of ZooKeeper nodes to which the Kafka binder can connect.

Default: localhost.

spring.cloud.stream.kafka.binder.defaultZkPort

zkNodes allows hosts specified with or without port information (e.g., host1,host2:port2). +This sets the default port when no port is configured in the node list.

Default: 2181.

spring.cloud.stream.kafka.binder.configuration

Key/Value map of client properties (both producers and consumer) passed to all clients created by the binder. +Due to the fact that these properties will be used by both producers and consumers, usage should be restricted to common properties, especially security settings.

Default: Empty map.

spring.cloud.stream.kafka.binder.headers

The list of custom headers that will be transported by the binder.

Default: empty.

spring.cloud.stream.kafka.binder.healthTimeout

The time to wait to get partition information in seconds; default 60. +Health will report as down if this timer expires.

Default: 10.

spring.cloud.stream.kafka.binder.offsetUpdateTimeWindow

The frequency, in milliseconds, with which offsets are saved. +Ignored if 0.

Default: 10000.

spring.cloud.stream.kafka.binder.offsetUpdateCount

The frequency, in number of updates, which which consumed offsets are persisted. +Ignored if 0. +Mutually exclusive with offsetUpdateTimeWindow.

Default: 0.

spring.cloud.stream.kafka.binder.requiredAcks

The number of required acks on the broker.

Default: 1.

spring.cloud.stream.kafka.binder.minPartitionCount

Effective only if autoCreateTopics or autoAddPartitions is set. +The global minimum number of partitions that the binder will configure on topics on which it produces/consumes data. +It can be superseded by the partitionCount setting of the producer or by the value of instanceCount * concurrency settings of the producer (if either is larger).

Default: 1.

spring.cloud.stream.kafka.binder.replicationFactor

The replication factor of auto-created topics if autoCreateTopics is active.

Default: 1.

spring.cloud.stream.kafka.binder.autoCreateTopics

If set to true, the binder will create new topics automatically. +If set to false, the binder will rely on the topics being already configured. +In the latter case, if the topics do not exist, the binder will fail to start. +Of note, this setting is independent of the auto.topic.create.enable setting of the broker and it does not influence it: if the server is set to auto-create topics, they may be created as part of the metadata retrieval request, with default broker settings.

Default: true.

spring.cloud.stream.kafka.binder.autoAddPartitions

If set to true, the binder will create add new partitions if required. +If set to false, the binder will rely on the partition size of the topic being already configured. +If the partition count of the target topic is smaller than the expected value, the binder will fail to start.

Default: false.

spring.cloud.stream.kafka.binder.socketBufferSize

Size (in bytes) of the socket buffer to be used by the Kafka consumers.

Default: 2097152.

37.3.2 Kafka Consumer Properties

The following properties are available for Kafka consumers only and +must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.consumer..

autoRebalanceEnabled

When true, topic partitions will be automatically rebalanced between the members of a consumer group. +When false, each consumer will be assigned a fixed set of partitions based on spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex. +This requires both spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex properties to be set appropriately on each launched instance. +The property spring.cloud.stream.instanceCount must typically be greater than 1 in this case.

Default: true.

autoCommitOffset

Whether to autocommit offsets when a message has been processed. +If set to false, a header with the key kafka_acknowledgment of the type org.springframework.kafka.support.Acknowledgment header will be present in the inbound message. +Applications may use this header for acknowledging messages. +See the examples section for details. +When this property is set to false, Kafka binder will set the ack mode to org.springframework.kafka.listener.AbstractMessageListenerContainer.AckMode.MANUAL.

Default: true.

autoCommitOnError

Effective only if autoCommitOffset is set to true. +If set to false it suppresses auto-commits for messages that result in errors, and will commit only for successful messages, allows a stream to automatically replay from the last successfully processed message, in case of persistent failures. +If set to true, it will always auto-commit (if auto-commit is enabled). +If not set (default), it effectively has the same value as enableDlq, auto-committing erroneous messages if they are sent to a DLQ, and not committing them otherwise.

Default: not set.

recoveryInterval

The interval between connection recovery attempts, in milliseconds.

Default: 5000.

startOffset

The starting offset for new groups. +Allowed values: earliest, latest. +If the consumer group is set explicitly for the consumer 'binding' (via spring.cloud.stream.bindings.<channelName>.group), then 'startOffset' is set to earliest; otherwise it is set to latest for the anonymous consumer group.

Default: null (equivalent to earliest).

enableDlq

When set to true, it will send enable DLQ behavior for the consumer. +By default, messages that result in errors will be forwarded to a topic named error.<destination>.<group>. +The DLQ topic name can be configurable via the property dlqName. +This provides an alternative option to the more common Kafka replay scenario for the case when the number of errors is relatively small and replaying the entire original topic may be too cumbersome.

Default: false.

configuration

Map with a key/value pair containing generic Kafka consumer properties.

Default: Empty map.

dlqName

The name of the DLQ topic to receive the error messages.

Default: null (If not specified, messages that result in errors will be forwarded to a topic named error.<destination>.<group>).

37.3.3 Kafka Producer Properties

The following properties are available for Kafka producers only and +must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.producer..

bufferSize

Upper limit, in bytes, of how much data the Kafka producer will attempt to batch before sending.

Default: 16384.

sync

Whether the producer is synchronous.

Default: false.

batchTimeout

How long the producer will wait before sending in order to allow more messages to accumulate in the same batch. +(Normally the producer does not wait at all, and simply sends all the messages that accumulated while the previous send was in progress.) A non-zero value may increase throughput at the expense of latency.

Default: 0.

messageKeyExpression

A SpEL expression evaluated against the outgoing message used to populate the key of the produced Kafka message. +For example headers.key or payload.myKey.

Default: none.

configuration

Map with a key/value pair containing generic Kafka producer properties.

Default: Empty map.

[Note]Note

The Kafka binder will use the partitionCount setting of the producer as a hint to create a topic with the given partition count (in conjunction with the minPartitionCount, the maximum of the two being the value being used). +Exercise caution when configuring both minPartitionCount for a binder and partitionCount for an application, as the larger value will be used. +If a topic already exists with a smaller partition count and autoAddPartitions is disabled (the default), then the binder will fail to start. +If a topic already exists with a smaller partition count and autoAddPartitions is enabled, new partitions will be added. +If a topic already exists with a larger number of partitions than the maximum of (minPartitionCount and partitionCount), the existing partition count will be used.

37.3.4 Usage examples

In this section, we illustrate the use of the above properties for specific scenarios.

Example: Setting autoCommitOffset false and relying on manual acking.

This example illustrates how one may manually acknowledge offsets in a consumer application.

This example requires that spring.cloud.stream.kafka.bindings.input.consumer.autoCommitOffset is set to false. +Use the corresponding input channel name for your example.

@SpringBootApplication
+@EnableBinding(Sink.class)
+public class ManuallyAcknowdledgingConsumer {
+
+ public static void main(String[] args) {
+     SpringApplication.run(ManuallyAcknowdledgingConsumer.class, args);
+ }
+
+ @StreamListener(Sink.INPUT)
+ public void process(Message<?> message) {
+     Acknowledgment acknowledgment = message.getHeaders().get(KafkaHeaders.ACKNOWLEDGMENT, Acknowledgment.class);
+     if (acknowledgment != null) {
+         System.out.println("Acknowledgment provided");
+         acknowledgment.acknowledge();
+     }
+ }
+}

Example: security configuration

Apache Kafka 0.9 supports secure connections between client and brokers. +To take advantage of this feature, follow the guidelines in the Apache Kafka Documentation as well as the Kafka 0.9 security guidelines from the Confluent documentation. +Use the spring.cloud.stream.kafka.binder.configuration option to set security properties for all clients created by the binder.

For example, for setting security.protocol to SASL_SSL, set:

spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_SSL

All the other security properties can be set in a similar manner.

When using Kerberos, follow the instructions in the reference documentation for creating and referencing the JAAS configuration.

Spring Cloud Stream supports passing JAAS configuration information to the application using a JAAS configuration file and using Spring Boot properties.

Using JAAS configuration files

The JAAS, and (optionally) krb5 file locations can be set for Spring Cloud Stream applications by using system properties. +Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using a JAAS configuration file:

 java -Djava.security.auth.login.config=/path.to/kafka_client_jaas.conf -jar log.jar \
+   --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \
+   --spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \
+   --spring.cloud.stream.bindings.input.destination=stream.ticktock \
+   --spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT
Using Spring Boot properties

As an alternative to having a JAAS configuration file, Spring Cloud Stream provides a mechanism for setting up the JAAS configuration for Spring Cloud Stream applications using Spring Boot properties.

The following properties can be used for configuring the login context of the Kafka client.

spring.cloud.stream.kafka.binder.jaas.loginModule

The login module name. Not necessary to be set in normal cases.

Default: com.sun.security.auth.module.Krb5LoginModule.

spring.cloud.stream.kafka.binder.jaas.controlFlag

The control flag of the login module.

Default: required.

spring.cloud.stream.kafka.binder.jaas.options

Map with a key/value pair containing the login module options.

Default: Empty map.

Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using Spring Boot configuration properties:

 java --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \
+   --spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \
+   --spring.cloud.stream.bindings.input.destination=stream.ticktock \
+   --spring.cloud.stream.kafka.binder.autoCreateTopics=false \
+   --spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT \
+   --spring.cloud.stream.kafka.binder.jaas.options.useKeyTab=true \
+   --spring.cloud.stream.kafka.binder.jaas.options.storeKey=true \
+   --spring.cloud.stream.kafka.binder.jaas.options.keyTab=/etc/security/keytabs/kafka_client.keytab \
+   --spring.cloud.stream.kafka.binder.jaas.options.principal=kafka-client-1@EXAMPLE.COM

This represents the equivalent of the following JAAS file:

KafkaClient {
+    com.sun.security.auth.module.Krb5LoginModule required
+    useKeyTab=true
+    storeKey=true
+    keyTab="/etc/security/keytabs/kafka_client.keytab"
+    principal="kafka-client-1@EXAMPLE.COM";
+};

If the topics required already exist on the broker, or will be created by an administrator, autocreation can be turned off and only client JAAS properties need to be sent. As an alternative to setting spring.cloud.stream.kafka.binder.autoCreateTopics you can simply remove the broker dependency from the application. See the section called “Excluding Kafka broker jar from the classpath of the binder based application” for details.

[Note]Note

Do not mix JAAS configuration files and Spring Boot properties in the same application. +If the -Djava.security.auth.login.config system property is already present, Spring Cloud Stream will ignore the Spring Boot properties.

[Note]Note

Exercise caution when using the autoCreateTopics and autoAddPartitions if using Kerberos. +Usually applications may use principals that do not have administrative rights in Kafka and Zookeeper, and relying on Spring Cloud Stream to create/modify topics may fail. +In secure environments, we strongly recommend creating topics and managing ACLs administratively using Kafka tooling.

Using the binder with Apache Kafka 0.10

The default Kafka support in Spring Cloud Stream Kafka binder is for Kafka version 0.10.1.1. The binder also supports connecting to other 0.10 based versions and 0.9 clients. +In order to do this, when you create the project that contains your application, include spring-cloud-starter-stream-kafka as you normally would do for the default binder. +Then add these dependencies at the top of the <dependencies> section in the pom.xml file to override the dependencies.

Here is an example for downgrading your application to 0.10.0.1. Since it is still on the 0.10 line, the default spring-kafka and spring-integration-kafka versions can be retained.

<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka_2.11</artifactId>
+  <version>0.10.0.1</version>
+  <exclusions>
+    <exclusion>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-log4j12</artifactId>
+    </exclusion>
+  </exclusions>
+</dependency>
+<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka-clients</artifactId>
+  <version>0.10.0.1</version>
+</dependency>

Here is another example of using 0.9.0.1 version.

<dependency>
+  <groupId>org.springframework.kafka</groupId>
+  <artifactId>spring-kafka</artifactId>
+  <version>1.0.5.RELEASE</version>
+</dependency>
+<dependency>
+  <groupId>org.springframework.integration</groupId>
+  <artifactId>spring-integration-kafka</artifactId>
+  <version>2.0.1.RELEASE</version>
+</dependency>
+<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka_2.11</artifactId>
+  <version>0.9.0.1</version>
+  <exclusions>
+    <exclusion>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-log4j12</artifactId>
+    </exclusion>
+  </exclusions>
+</dependency>
+<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka-clients</artifactId>
+  <version>0.9.0.1</version>
+</dependency>
[Note]Note

The versions above are provided only for the sake of the example. +For best results, we recommend using the most recent 0.10-compatible versions of the projects.

Excluding Kafka broker jar from the classpath of the binder based application

The Apache Kafka Binder uses the administrative utilities which are part of the Apache Kafka server library to create and reconfigure topics. +If the inclusion of the Apache Kafka server library and its dependencies is not necessary at runtime because the application will rely on the topics being configured administratively, the Kafka binder allows for Apache Kafka server dependency to be excluded from the application.

If you use non default versions for Kafka dependencies as advised above, all you have to do is not to include the kafka broker dependency. +If you use the default Kafka version, then ensure that you exclude the kafka broker jar from the spring-cloud-starter-stream-kafka dependency as following.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-starter-stream-kafka</artifactId>
+  <exclusions>
+    <exclusion>
+      <groupId>org.apache.kafka</groupId>
+      <artifactId>kafka_2.11</artifactId>
+    </exclusion>
+  </exclusions>
+</dependency>

If you exclude the Apache Kafka server dependency and the topic is not present on the server, then the Apache Kafka broker will create the topic if auto topic creation is enabled on the server. +Please keep in mind that if you are relying on this, then the Kafka server will use the default number of partitions and replication factors. +On the other hand, if auto topic creation is disabled on the server, then care must be taken before running the application to create the topic with the desired number of partitions.

If you want to have full control over how partitions are allocated, then leave the default settings as they are, i.e. do not exclude the kafka broker jar and ensure that spring.cloud.stream.kafka.binder.autoCreateTopics is set to true, which is the default.

37.4 Kafka Streams Binding Capabilities of Spring Cloud Stream

Spring Cloud Stream Kafka support also includes a binder specifically designed for Kafka Streams binding. +Using this binder, applications can be written that leverage the Kafka Streams API. +For more information on Kafka Streams, see Kafka Streams API Developer Manual

Kafka Streams support in Spring Cloud Stream is based on the foundations provided by the Spring Kafka project. For details on that support, see Kafaka Streams Support in Spring Kafka.

Here are the maven coordinates for the Spring Cloud Stream KStream binder artifact.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-kstream</artifactId>
+</dependency>

In addition to leveraging the Spring Cloud Stream programming model which is based on Spring Boot, one of the main other benefits that the KStream binder provides is the fact that it avoids the boilerplate configuration that one needs to write when using the Kafka Streams API directly. +High level streams DSL provided through the Kafka Streams API can be used through Spring Cloud Stream in the current support.

37.4.1 Usage example of high level streams DSL

This application will listen from a Kafka topic and write the word count for each unique word that it sees in a 5 seconds time window.

@SpringBootApplication
+@EnableBinding(KStreamProcessor.class)
+public class WordCountProcessorApplication {
+
+	@StreamListener("input")
+	@SendTo("output")
+	public KStream<?, String> process(KStream<?, String> input) {
+		return input
+				.flatMapValues(value -> Arrays.asList(value.toLowerCase().split("\\W+")))
+				.map((key, word) -> new KeyValue<>(word, word))
+				.groupByKey(Serdes.String(), Serdes.String())
+				.count(TimeWindows.of(5000), "store-name")
+				.toStream()
+				.map((w, c) -> new KeyValue<>(null, "Count for " + w.key() + ": " + c));
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(WordCountProcessorApplication.class, args);
+	}

If you build it as Spring Boot runnable fat jar, you can run the above example in the following way:

java -jar uber.jar  --spring.cloud.stream.bindings.input.destination=words --spring.cloud.stream.bindings.output.destination=counts

This means that the application will listen from the incoming Kafka topic words and write to the output topic counts.

Spring Cloud Stream will ensure that the messages from both the incoming and outgoing topics are bound as KStream objects. +As one may observe, the developer can exclusively focus on the business aspects of the code, i.e. writing the logic required in the processor rather than setting up the streams specific configuration required by the Kafka Streams infrastructure. +All those boilerplate is handled by Spring Cloud Stream behind the scenes.

37.4.2 Support for interactive queries

If access to the KafkaStreams is needed for interactive queries, the internal KafkaStreams instance can be accessed via KStreamBuilderFactoryBean.getKafkaStreams(). +You can autowire the KStreamBuilderFactoryBean instance provided by the KStream binder. Then you can get KafkaStreams instance from it and retrieve the underlying store, execute queries on it, etc.

37.4.3 Kafka Streams properties

configuration

Map with a key/value pair containing properties pertaining to Kafka Streams API. +This property must be prefixed with spring.cloud.stream.kstream.binder..

Following are some examples of using this property.
spring.cloud.stream.kstream.binder.configuration.key.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
+spring.cloud.stream.kstream.binder.configuration.value.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
+spring.cloud.stream.kstream.binder.configuration.commit.interval.ms=1000
For more information about all the properties that may go into streams configuration, see StreamsConfig JavaDocs.

There can also be binding specific properties.

For instance, you can use a different Serde for your input or output destination.

spring.cloud.stream.kstream.bindings.output.producer.keySerde=org.apache.kafka.common.serialization.Serdes$IntegerSerde
+spring.cloud.stream.kstream.bindings.output.producer.valueSerde=org.apache.kafka.common.serialization.Serdes$LongSerde
timewindow.length

Many streaming applications written using Kafka Streams involve windowning operations. +If you specify this property, there is a org.apache.kafka.streams.kstream.TimeWindows bean automatically provided that can be autowired in applications. +This property must be prefixed with spring.cloud.stream.kstream.. +A bean of type org.apache.kafka.streams.kstream.TimeWindows is created only if this property is provided.

Following is an example of using this property.
+Values are provided in milliseconds.
spring.cloud.stream.kstream.timeWindow.length=5000
timewindow.advanceBy

This property goes hand in hand with timewindow.length and has no effect on its own. +If you provide this property, the generated org.apache.kafka.streams.kstream.TimeWindows bean will automatically conatin this information. +This property must be prefixed with spring.cloud.stream.kstream..

Following is an example of using this property.
+Values are provided in milliseconds.
spring.cloud.stream.kstream.timeWindow.advanceBy=1000

37.5 Error Channels

Starting with version 1.3, the binder unconditionally sends exceptions to an error channel for each consumer destination, and can be configured to send async producer send failures to an error channel too. +See the section called “Message Channel Binders and Error Channels” for more information.

The payload of the ErrorMessage for a send failure is a KafkaSendFailureException with properties:

  • failedMessage - the spring-messaging Message<?> that failed to be sent.
  • record - the raw ProducerRecord that was created from the failedMessage

There is no automatic handling of these exceptions (such as sending to a Dead-Letter queue); you can consume these exceptions with your own Spring Integration flow.

37.6 Kafka Metrics

Kafka binder module exposes the following metrics:

spring.cloud.stream.binder.kafka.someGroup.someTopic.lag - this metric indicates how many messages have not been yet consumed from given binder’s topic by given consumer group. +For example if the value of the metric spring.cloud.stream.binder.kafka.myGroup.myTopic.lag is 1000, then consumer group myGroup has 1000 messages to waiting to be consumed from topic myTopic. +This metric is particularly useful to provide auto-scaling feedback to PaaS platform of your choice.

37.7 Dead-Letter Topic Processing

Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them. +If the reason for the dead-lettering is transient, you may wish to route the messages back to the original topic. +However, if the problem is a permanent issue, that could cause an infinite loop. +The following spring-boot application is an example of how to route those messages back to the original topic, but moves them to a third "parking lot" topic after three attempts. +The application is simply another spring-cloud-stream application that reads from the dead-letter topic. +It terminates when no messages are received for 5 seconds.

The examples assume the original destination is so8400out and the consumer group is so8400.

There are several considerations.

  • Consider only running the rerouting when the main application is not running. +Otherwise, the retries for transient errors will be used up very quickly.
  • Alternatively, use a two-stage approach - use this application to route to a third topic, and another to route from there back to the main topic.
  • Since this technique uses a message header to keep track of retries, it won’t work with headerMode=raw. +In that case, consider adding some data to the payload (that can be ignored by the main application).
  • x-retries has to be added to the headers property spring.cloud.stream.kafka.binder.headers=x-retries on both this, and the main application so that the header is transported between the applications.
  • Since kafka is publish/subscribe, replayed messages will be sent to each consumer group, even those that successfully processed a message the first time around.

application.properties.  +

spring.cloud.stream.bindings.input.group=so8400replay
+spring.cloud.stream.bindings.input.destination=error.so8400out.so8400
+
+spring.cloud.stream.bindings.output.destination=so8400out
+spring.cloud.stream.bindings.output.producer.partitioned=true
+
+spring.cloud.stream.bindings.parkingLot.destination=so8400in.parkingLot
+spring.cloud.stream.bindings.parkingLot.producer.partitioned=true
+
+spring.cloud.stream.kafka.binder.configuration.auto.offset.reset=earliest
+
+spring.cloud.stream.kafka.binder.headers=x-retries

+

Application.  +

@SpringBootApplication
+@EnableBinding(TwoOutputProcessor.class)
+public class ReRouteDlqKApplication implements CommandLineRunner {
+
+    private static final String X_RETRIES_HEADER = "x-retries";
+
+    public static void main(String[] args) {
+        SpringApplication.run(ReRouteDlqKApplication.class, args).close();
+    }
+
+    private final AtomicInteger processed = new AtomicInteger();
+
+    @Autowired
+    private MessageChannel parkingLot;
+
+    @StreamListener(Processor.INPUT)
+    @SendTo(Processor.OUTPUT)
+    public Message<?> reRoute(Message<?> failed) {
+        processed.incrementAndGet();
+        Integer retries = failed.getHeaders().get(X_RETRIES_HEADER, Integer.class);
+        if (retries == null) {
+            System.out.println("First retry for " + failed);
+            return MessageBuilder.fromMessage(failed)
+                    .setHeader(X_RETRIES_HEADER, new Integer(1))
+                    .setHeader(BinderHeaders.PARTITION_OVERRIDE,
+                            failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID))
+                    .build();
+        }
+        else if (retries.intValue() < 3) {
+            System.out.println("Another retry for " + failed);
+            return MessageBuilder.fromMessage(failed)
+                    .setHeader(X_RETRIES_HEADER, new Integer(retries.intValue() + 1))
+                    .setHeader(BinderHeaders.PARTITION_OVERRIDE,
+                            failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID))
+                    .build();
+        }
+        else {
+            System.out.println("Retries exhausted for " + failed);
+            parkingLot.send(MessageBuilder.fromMessage(failed)
+                    .setHeader(BinderHeaders.PARTITION_OVERRIDE,
+                            failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID))
+                    .build());
+        }
+        return null;
+    }
+
+    @Override
+    public void run(String... args) throws Exception {
+        while (true) {
+            int count = this.processed.get();
+            Thread.sleep(5000);
+            if (count == this.processed.get()) {
+                System.out.println("Idle, terminating");
+                return;
+            }
+        }
+    }
+
+    public interface TwoOutputProcessor extends Processor {
+
+        @Output("parkingLot")
+        MessageChannel parkingLot();
+
+    }
+
+}

+

Prev Up Next
Part V. Binder Implementations Home 38. RabbitMQ Binder
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Part XVI. Appendix: Compendium of Configuration Properties
Prev   

Part XVI. Appendix: Compendium of Configuration Properties

NameDefaultDescription

archaius.propagate.environmentChangedEvent

true

Propagates EnvironmentChanged events to Archaius ConfigurationManager.

encrypt.fail-on-error

true

Flag to say that a process should fail if there is an encryption or decryption error.

encrypt.key

 

A symmetric key. As a stronger alternative consider using a keystore.

encrypt.key-store.alias

 

Alias for a key in the store.

encrypt.key-store.location

 

Location of the key store file, e.g. classpath:/keystore.jks.

encrypt.key-store.password

 

Password that locks the keystore.

encrypt.key-store.secret

 

Secret protecting the key (defaults to the same as the password).

encrypt.rsa.algorithm

 

The RSA algorithm to use (DEFAULT or OEAP). Once it is set do not change it (or existing ciphers will not a decryptable).

encrypt.rsa.salt

deadbeef

Salt for the random secret used to encrypt cipher text. Once it is set do not change it (or existing ciphers will not a decryptable).

encrypt.rsa.strong

false

Flag to indicate that "strong" AES encryption should be used internally. If true then the GCM algorithm is applied to the AES encrypted bytes. Default is false (in which case "standard" CBC is used instead). Once it is set do not change it (or existing ciphers will not a decryptable).

endpoints.bus.enabled

  

endpoints.bus.id

  

endpoints.bus.sensitive

  

endpoints.consul.enabled

  

endpoints.consul.id

  

endpoints.consul.sensitive

  

endpoints.env.post.enabled

true

Enable changing the Environment through a POST to /env.

endpoints.features.enabled

  

endpoints.features.id

  

endpoints.features.sensitive

  

endpoints.pause.enabled

true

Enable the /pause endpoint (to send Lifecycle.stop()).

endpoints.pause.id

  

endpoints.pause.sensitive

  

endpoints.refresh.enabled

true

Enable the /refresh endpoint to refresh configuration and re-initialize refresh scoped beans.

endpoints.refresh.id

  

endpoints.refresh.sensitive

  

endpoints.restart.enabled

true

Enable the /restart endpoint to restart the application context.

endpoints.restart.id

  

endpoints.restart.pause-endpoint.enabled

  

endpoints.restart.pause-endpoint.id

  

endpoints.restart.pause-endpoint.sensitive

  

endpoints.restart.resume-endpoint.enabled

  

endpoints.restart.resume-endpoint.id

  

endpoints.restart.resume-endpoint.sensitive

  

endpoints.restart.sensitive

  

endpoints.restart.timeout

0

 

endpoints.resume.enabled

true

Enable the /resume endpoint (to send Lifecycle.start()).

endpoints.resume.id

  

endpoints.resume.sensitive

  

endpoints.routes.enabled

  

endpoints.routes.id

  

endpoints.routes.sensitive

  

endpoints.zookeeper.enabled

true

Enable the /zookeeper endpoint to inspect the state of zookeeper.

eureka.client.allow-redirects

false

Indicates whether server can redirect a client request to a backup server/cluster. If set to false, the server will handle the request directly, If set to true, it may send HTTP redirect to the client, with a new server location.

eureka.client.availability-zones

 

Gets the list of availability zones (used in AWS data centers) for the region in which this instance resides. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds.

eureka.client.backup-registry-impl

 

Gets the name of the implementation which implements BackupRegistry to fetch the registry information as a fall back option for only the first time when the eureka client starts. This may be needed for applications which needs additional resiliency for registry information without which it cannot operate.

eureka.client.cache-refresh-executor-exponential-back-off-bound

10

Cache refresh executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred.

eureka.client.cache-refresh-executor-thread-pool-size

2

The thread pool size for the cacheRefreshExecutor to initialise with

eureka.client.client-data-accept

 

EurekaAccept name for client data accept

eureka.client.decoder-name

 

This is a transient config and once the latest codecs are stable, can be removed (as there will only be one)

eureka.client.disable-delta

false

Indicates whether the eureka client should disable fetching of delta and should rather resort to getting the full registry information. Note that the delta fetches can reduce the traffic tremendously, because the rate of change with the eureka server is normally much lower than the rate of fetches. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds

eureka.client.dollar-replacement

_-

Get a replacement string for Dollar sign <code>$</code> during serializing/deserializing information in eureka server.

eureka.client.enabled

true

Flag to indicate that the Eureka client is enabled.

eureka.client.encoder-name

 

This is a transient config and once the latest codecs are stable, can be removed (as there will only be one)

eureka.client.escape-char-replacement

__

Get a replacement string for underscore sign <code>_</code> during serializing/deserializing information in eureka server.

eureka.client.eureka-connection-idle-timeout-seconds

30

Indicates how much time (in seconds) that the HTTP connections to eureka server can stay idle before it can be closed. In the AWS environment, it is recommended that the values is 30 seconds or less, since the firewall cleans up the connection information after a few mins leaving the connection hanging in limbo

eureka.client.eureka-server-connect-timeout-seconds

5

Indicates how long to wait (in seconds) before a connection to eureka server needs to timeout. Note that the connections in the client are pooled by org.apache.http.client.HttpClient and this setting affects the actual connection creation and also the wait time to get the connection from the pool.

eureka.client.eureka-server-d-n-s-name

 

Gets the DNS name to be queried to get the list of eureka servers.This information is not required if the contract returns the service urls by implementing serviceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.

eureka.client.eureka-server-port

 

Gets the port to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS.This information is not required if the contract returns the service urls eurekaServerServiceUrls(String). The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.

eureka.client.eureka-server-read-timeout-seconds

8

Indicates how long to wait (in seconds) before a read from eureka server needs to timeout.

eureka.client.eureka-server-total-connections

200

Gets the total number of connections that is allowed from eureka client to all eureka servers.

eureka.client.eureka-server-total-connections-per-host

50

Gets the total number of connections that is allowed from eureka client to a eureka server host.

eureka.client.eureka-server-u-r-l-context

 

Gets the URL context to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS. This information is not required if the contract returns the service urls from eurekaServerServiceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.

eureka.client.eureka-service-url-poll-interval-seconds

0

Indicates how often(in seconds) to poll for changes to eureka server information. Eureka servers could be added or removed and this setting controls how soon the eureka clients should know about it.

eureka.client.fetch-registry

true

Indicates whether this client should fetch eureka registry information from eureka server.

eureka.client.fetch-remote-regions-registry

 

Comma separated list of regions for which the eureka registry information will be fetched. It is mandatory to define the availability zones for each of these regions as returned by availabilityZones. Failing to do so, will result in failure of discovery client startup.

eureka.client.filter-only-up-instances

true

Indicates whether to get the applications after filtering the applications for instances with only InstanceStatus UP states.

eureka.client.g-zip-content

true

Indicates whether the content fetched from eureka server has to be compressed whenever it is supported by the server. The registry information from the eureka server is compressed for optimum network traffic.

eureka.client.healthcheck.enabled

true

Enables the Eureka health check handler.

eureka.client.heartbeat-executor-exponential-back-off-bound

10

Heartbeat executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred.

eureka.client.heartbeat-executor-thread-pool-size

2

The thread pool size for the heartbeatExecutor to initialise with

eureka.client.initial-instance-info-replication-interval-seconds

40

Indicates how long initially (in seconds) to replicate instance info to the eureka server

eureka.client.instance-info-replication-interval-seconds

30

Indicates how often(in seconds) to replicate instance changes to be replicated to the eureka server.

eureka.client.log-delta-diff

false

Indicates whether to log differences between the eureka server and the eureka client in terms of registry information. Eureka client tries to retrieve only delta changes from eureka server to minimize network traffic. After receiving the deltas, eureka client reconciles the information from the server to verify it has not missed out some information. Reconciliation failures could happen when the client has had network issues communicating to server.If the reconciliation fails, eureka client gets the full registry information. While getting the full registry information, the eureka client can log the differences between the client and the server and this setting controls that. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSecondsr

eureka.client.on-demand-update-status-change

true

If set to true, local status updates via ApplicationInfoManager will trigger on-demand (but rate limited) register/updates to remote eureka servers

eureka.client.prefer-same-zone-eureka

true

Indicates whether or not this instance should try to use the eureka server in the same zone for latency and/or other reason. Ideally eureka clients are configured to talk to servers in the same zone The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds

eureka.client.property-resolver

  

eureka.client.proxy-host

 

Gets the proxy host to eureka server if any.

eureka.client.proxy-password

 

Gets the proxy password if any.

eureka.client.proxy-port

 

Gets the proxy port to eureka server if any.

eureka.client.proxy-user-name

 

Gets the proxy user name if any.

eureka.client.region

us-east-1

Gets the region (used in AWS datacenters) where this instance resides.

eureka.client.register-with-eureka

true

Indicates whether or not this instance should register its information with eureka server for discovery by others. In some cases, you do not want your instances to be discovered whereas you just want do discover other instances.

eureka.client.registry-fetch-interval-seconds

30

Indicates how often(in seconds) to fetch the registry information from the eureka server.

eureka.client.registry-refresh-single-vip-address

 

Indicates whether the client is only interested in the registry information for a single VIP.

eureka.client.service-url

 

Map of availability zone to list of fully qualified URLs to communicate with eureka server. Each value can be a single URL or a comma separated list of alternative locations. Typically the eureka server URLs carry protocol,host,port,context and version information if any. Example: https://ec2-256-156-243-129.compute-1.amazonaws.com:7001/eureka/ The changes are effective at runtime at the next service url refresh cycle as specified by eurekaServiceUrlPollIntervalSeconds.

eureka.client.use-dns-for-fetching-service-urls

false

Indicates whether the eureka client should use the DNS mechanism to fetch a list of eureka servers to talk to. When the DNS name is updated to have additional servers, that information is used immediately after the eureka client polls for that information as specified in eurekaServiceUrlPollIntervalSeconds. Alternatively, the service urls can be returned serviceUrls, but the users should implement their own mechanism to return the updated list in case of changes. The changes are effective at runtime.

eureka.dashboard.enabled

true

Flag to enable the Eureka dashboard. Default true.

eureka.dashboard.path

/

The path to the Eureka dashboard (relative to the servlet path). Defaults to "/".

eureka.instance.a-s-g-name

 

Gets the AWS autoscaling group name associated with this instance. This information is specifically used in an AWS environment to automatically put an instance out of service after the instance is launched and it has been disabled for traffic..

eureka.instance.app-group-name

 

Get the name of the application group to be registered with eureka.

eureka.instance.appname

unknown

Get the name of the application to be registered with eureka.

eureka.instance.data-center-info

 

Returns the data center this instance is deployed. This information is used to get some AWS specific instance information if the instance is deployed in AWS.

eureka.instance.default-address-resolution-order

[]

 

eureka.instance.environment

  

eureka.instance.health-check-url

 

Gets the absolute health check page URL for this instance. The users can provide the healthCheckUrlPath if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime.

eureka.instance.health-check-url-path

/health

Gets the relative health check URL path for this instance. The health check page URL is then constructed out of the hostname and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage.

eureka.instance.home-page-url

 

Gets the absolute home page URL for this instance. The users can provide the homePageUrlPath if the home page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to use it as a landing page. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime.

eureka.instance.home-page-url-path

/

Gets the relative home page URL Path for this instance. The home page URL is then constructed out of the hostName and the type of communication - secure or unsecure. It is normally used for informational purposes for other services to use it as a landing page.

eureka.instance.hostname

 

The hostname if it can be determined at configuration time (otherwise it will be guessed from OS primitives).

eureka.instance.initial-status

 

Initial status to register with rmeote Eureka server.

eureka.instance.instance-enabled-onit

false

Indicates whether the instance should be enabled for taking traffic as soon as it is registered with eureka. Sometimes the application might need to do some pre-processing before it is ready to take traffic.

eureka.instance.instance-id

 

Get the unique Id (within the scope of the appName) of this instance to be registered with eureka.

eureka.instance.ip-address

 

Get the IPAdress of the instance. This information is for academic purposes only as the communication from other instances primarily happen using the information supplied in {@link #getHostName(boolean)}.

eureka.instance.lease-expiration-duration-in-seconds

90

Indicates the time in seconds that the eureka server waits since it received the last heartbeat before it can remove this instance from its view and there by disallowing traffic to this instance. Setting this value too long could mean that the traffic could be routed to the instance even though the instance is not alive. Setting this value too small could mean, the instance may be taken out of traffic because of temporary network glitches.This value to be set to atleast higher than the value specified in leaseRenewalIntervalInSeconds.

eureka.instance.lease-renewal-interval-in-seconds

30

Indicates how often (in seconds) the eureka client needs to send heartbeats to eureka server to indicate that it is still alive. If the heartbeats are not received for the period specified in leaseExpirationDurationInSeconds, eureka server will remove the instance from its view, there by disallowing traffic to this instance. Note that the instance could still not take traffic if it implements HealthCheckCallback and then decides to make itself unavailable.

eureka.instance.metadata-map

 

Gets the metadata name/value pairs associated with this instance. This information is sent to eureka server and can be used by other instances.

eureka.instance.namespace

eureka

Get the namespace used to find properties. Ignored in Spring Cloud.

eureka.instance.non-secure-port

80

Get the non-secure port on which the instance should receive traffic.

eureka.instance.non-secure-port-enabled

true

Indicates whether the non-secure port should be enabled for traffic or not.

eureka.instance.prefer-ip-address

false

Flag to say that, when guessing a hostname, the IP address of the server should be used in prference to the hostname reported by the OS.

eureka.instance.registry.default-open-for-traffic-count

1

Value used in determining when leases are cancelled, default to 1 for standalone. Should be set to 0 for peer replicated eurekas

eureka.instance.registry.expected-number-of-renews-per-min

1

 

eureka.instance.secure-health-check-url

 

Gets the absolute secure health check page URL for this instance. The users can provide the secureHealthCheckUrl if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime.

eureka.instance.secure-port

443

Get the Secure port on which the instance should receive traffic.

eureka.instance.secure-port-enabled

false

Indicates whether the secure port should be enabled for traffic or not.

eureka.instance.secure-virtual-host-name

unknown

Gets the secure virtual host name defined for this instance. This is typically the way other instance would find this instance by using the secure virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance.

eureka.instance.status-page-url

 

Gets the absolute status page URL path for this instance. The users can provide the statusPageUrlPath if the status page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance.

eureka.instance.status-page-url-path

/info

Gets the relative status page URL path for this instance. The status page URL is then constructed out of the hostName and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance.

eureka.instance.virtual-host-name

unknown

Gets the virtual host name defined for this instance. This is typically the way other instance would find this instance by using the virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance.

eureka.server.a-s-g-cache-expiry-timeout-ms

0

 

eureka.server.a-s-g-query-timeout-ms

300

 

eureka.server.a-s-g-update-interval-ms

0

 

eureka.server.a-w-s-access-id

  

eureka.server.a-w-s-secret-key

  

eureka.server.batch-replication

false

 

eureka.server.binding-strategy

  

eureka.server.delta-retention-timer-interval-in-ms

0

 

eureka.server.disable-delta

false

 

eureka.server.disable-delta-for-remote-regions

false

 

eureka.server.disable-transparent-fallback-to-other-region

false

 

eureka.server.e-i-p-bind-rebind-retries

3

 

eureka.server.e-i-p-binding-retry-interval-ms

0

 

eureka.server.e-i-p-binding-retry-interval-ms-when-unbound

0

 

eureka.server.enable-replicated-request-compression

false

 

eureka.server.enable-self-preservation

true

 

eureka.server.eviction-interval-timer-in-ms

0

 

eureka.server.g-zip-content-from-remote-region

true

 

eureka.server.json-codec-name

  

eureka.server.list-auto-scaling-groups-role-name

ListAutoScalingGroups

 

eureka.server.log-identity-headers

true

 

eureka.server.max-elements-in-peer-replication-pool

10000

 

eureka.server.max-elements-in-status-replication-pool

10000

 

eureka.server.max-idle-thread-age-in-minutes-for-peer-replication

15

 

eureka.server.max-idle-thread-in-minutes-age-for-status-replication

10

 

eureka.server.max-threads-for-peer-replication

20

 

eureka.server.max-threads-for-status-replication

1

 

eureka.server.max-time-for-replication

30000

 

eureka.server.min-available-instances-for-peer-replication

-1

 

eureka.server.min-threads-for-peer-replication

5

 

eureka.server.min-threads-for-status-replication

1

 

eureka.server.number-of-replication-retries

5

 

eureka.server.peer-eureka-nodes-update-interval-ms

0

 

eureka.server.peer-eureka-status-refresh-time-interval-ms

0

 

eureka.server.peer-node-connect-timeout-ms

200

 

eureka.server.peer-node-connection-idle-timeout-seconds

30

 

eureka.server.peer-node-read-timeout-ms

200

 

eureka.server.peer-node-total-connections

1000

 

eureka.server.peer-node-total-connections-per-host

500

 

eureka.server.prime-aws-replica-connections

true

 

eureka.server.property-resolver

  

eureka.server.rate-limiter-burst-size

10

 

eureka.server.rate-limiter-enabled

false

 

eureka.server.rate-limiter-full-fetch-average-rate

100

 

eureka.server.rate-limiter-privileged-clients

  

eureka.server.rate-limiter-registry-fetch-average-rate

500

 

eureka.server.rate-limiter-throttle-standard-clients

false

 

eureka.server.registry-sync-retries

0

 

eureka.server.registry-sync-retry-wait-ms

0

 

eureka.server.remote-region-app-whitelist

  

eureka.server.remote-region-connect-timeout-ms

1000

 

eureka.server.remote-region-connection-idle-timeout-seconds

30

 

eureka.server.remote-region-fetch-thread-pool-size

20

 

eureka.server.remote-region-read-timeout-ms

1000

 

eureka.server.remote-region-registry-fetch-interval

30

 

eureka.server.remote-region-total-connections

1000

 

eureka.server.remote-region-total-connections-per-host

500

 

eureka.server.remote-region-trust-store

  

eureka.server.remote-region-trust-store-password

changeit

 

eureka.server.remote-region-urls

  

eureka.server.remote-region-urls-with-name

  

eureka.server.renewal-percent-threshold

0.85

 

eureka.server.renewal-threshold-update-interval-ms

0

 

eureka.server.response-cache-auto-expiration-in-seconds

180

 

eureka.server.response-cache-update-interval-ms

0

 

eureka.server.retention-time-in-m-s-in-delta-queue

0

 

eureka.server.route53-bind-rebind-retries

3

 

eureka.server.route53-binding-retry-interval-ms

0

 

eureka.server.route53-domain-t-t-l

30

 

eureka.server.sync-when-timestamp-differs

true

 

eureka.server.use-read-only-response-cache

true

 

eureka.server.wait-time-in-ms-when-sync-empty

0

 

eureka.server.xml-codec-name

  

feign.client.config

  

feign.client.default-config

default

 

feign.client.default-to-properties

true

 

feign.compression.request.mime-types

[text/xml, application/xml, application/json]

The list of supported mime types.

feign.compression.request.min-request-size

2048

The minimum threshold content size.

feign.httpclient.connection-timeout

2000

 

feign.httpclient.connection-timer-repeat

3000

 

feign.httpclient.disable-ssl-validation

false

 

feign.httpclient.follow-redirects

true

 

feign.httpclient.max-connections

200

 

feign.httpclient.max-connections-per-route

50

 

feign.httpclient.time-to-live

900

 

feign.httpclient.time-to-live-unit

  

health.config.enabled

false

Flag to indicate that the config server health indicator should be installed.

health.config.time-to-live

0

Time to live for cached result, in milliseconds. Default 300000 (5 min).

hystrix.metrics.enabled

true

Enable Hystrix metrics polling. Defaults to true.

hystrix.metrics.polling-interval-ms

2000

Interval between subsequent polling of metrics. Defaults to 2000 ms.

hystrix.shareSecurityContext

false

Enables auto-configuration of the Hystrix concurrency strategy plugin hook who will transfer the SecurityContext from your main thread to the one used by the Hystrix command.

management.health.refresh.enabled

true

Enable the health endpoint for the refresh scope.

management.health.zookeeper.enabled

true

Enable the health endpoint for zookeeper.

management.metrics.binders.hystrix.enabled

true

Enables creation of OK Http Client factory beans.

netflix.atlas.batch-size

10000

 

netflix.atlas.enabled

true

 

netflix.atlas.uri

  

netflix.metrics.servo.cache-warning-threshold

1000

When the ServoMonitorCache reaches this size, a warning is logged. This will be useful if you are using string concatenation in RestTemplate urls.

netflix.metrics.servo.registry-class

com.netflix.servo.BasicMonitorRegistry

Fully qualified class name for monitor registry used by Servo.

proxy.auth.load-balanced

false

 

proxy.auth.routes

 

Authentication strategy per route.

ribbon.eager-load.clients

  

ribbon.eager-load.enabled

false

 

ribbon.eureka.enabled

true

Enables the use of Eureka with Ribbon.

ribbon.http.client.enabled

false

Deprecated property to enable Ribbon RestClient.

ribbon.okhttp.enabled

false

Enables the use of the OK HTTP Client with Ribbon.

ribbon.restclient.enabled

false

Enables the use of the deprecated Ribbon RestClient.

ribbon.secure-ports

  

spring.cloud.bus.ack.destination-service

 

Service that wants to listen to acks. By default null (meaning all services).

spring.cloud.bus.ack.enabled

true

Flag to switch off acks (default on).

spring.cloud.bus.destination

springCloudBus

Name of Spring Cloud Stream destination for messages.

spring.cloud.bus.enabled

true

Flag to indicate that the bus is enabled.

spring.cloud.bus.env.enabled

true

Flag to switch off environment change events (default on).

spring.cloud.bus.refresh.enabled

true

Flag to switch off refresh events (default on).

spring.cloud.bus.trace.enabled

false

Flag to switch on tracing of acks (default off).

spring.cloud.cloudfoundry.discovery.enabled

true

Flag to indicate that discovery is enabled.

spring.cloud.cloudfoundry.discovery.heartbeat-frequency

5000

Frequency in milliseconds of poll for heart beat. The client will poll on this frequency and broadcast a list of service ids.

spring.cloud.cloudfoundry.discovery.org

 

Organization name to authenticate with (default to user’s default).

spring.cloud.cloudfoundry.discovery.password

 

Password for user to authenticate and obtain token.

spring.cloud.cloudfoundry.discovery.space

 

Space name to authenticate with (default to user’s default).

spring.cloud.cloudfoundry.discovery.url

https://api.run.pivotal.io

URL of Cloud Foundry API (Cloud Controller).

spring.cloud.cloudfoundry.discovery.username

 

Username to authenticate (usually an email address).

spring.cloud.compatibility-verifier.compatible-boot-versions

1.5.x

Default accepted versions for the Spring Boot dependency. You can set {@code x} for the patch version if you don’t want to specify a concrete value. Example: {@code 3.4.x}

spring.cloud.compatibility-verifier.enabled

false

Enables creation of Spring Cloud compatibility verification.

spring.cloud.config.allow-override

true

Flag to indicate that {@link #isOverrideSystemProperties() systemPropertiesOverride} can be used. Set to false to prevent users from changing the default accidentally. Default true.

spring.cloud.config.authorization

 

Authorization token used by the client to connect to the server.

spring.cloud.config.discovery.enabled

false

Flag to indicate that config server discovery is enabled (config server URL will be looked up via discovery).

spring.cloud.config.discovery.service-id

configserver

Service id to locate config server.

spring.cloud.config.enabled

true

Flag to say that remote configuration is enabled. Default true;

spring.cloud.config.fail-fast

false

Flag to indicate that failure to connect to the server is fatal (default false).

spring.cloud.config.headers

 

Additional headers used to create the client request.

spring.cloud.config.label

 

The label name to use to pull remote configuration properties. The default is set on the server (generally "master" for a git based server).

spring.cloud.config.name

 

Name of application used to fetch remote properties.

spring.cloud.config.override-none

false

Flag to indicate that when {@link #setAllowOverride(boolean) allowOverride} is true, external properties should take lowest priority, and not override any existing property sources (including local config files). Default false.

spring.cloud.config.override-system-properties

true

Flag to indicate that the external properties should override system properties. Default true.

spring.cloud.config.password

 

The password to use (HTTP Basic) when contacting the remote server.

spring.cloud.config.profile

default

The default profile to use when fetching remote configuration (comma-separated). Default is "default".

spring.cloud.config.retry.initial-interval

1000

Initial retry interval in milliseconds.

spring.cloud.config.retry.max-attempts

6

Maximum number of attempts.

spring.cloud.config.retry.max-interval

2000

Maximum interval for backoff.

spring.cloud.config.retry.multiplier

1.1

Multiplier for next interval.

spring.cloud.config.server.bootstrap

false

Flag indicating that the config server should initialize its own Environment with properties from the remote repository. Off by default because it delays startup but can be useful when embedding the server in another application.

spring.cloud.config.server.default-application-name

application

Default application name when incoming requests do not have a specific one.

spring.cloud.config.server.default-label

 

Default repository label when incoming requests do not have a specific label.

spring.cloud.config.server.default-profile

default

Default application profile when incoming requests do not have a specific one.

spring.cloud.config.server.encrypt.enabled

true

Enable decryption of environment properties before sending to client.

spring.cloud.config.server.git.basedir

 

Base directory for local working copy of repository.

spring.cloud.config.server.git.clone-on-start

false

Flag to indicate that the repository should be cloned on startup (not on demand). Generally leads to slower startup but faster first query.

spring.cloud.config.server.git.default-label

master

 

spring.cloud.config.server.git.delete-untracked-branches

false

Flag to indicate that the branch should be deleted locally if it’s origin tracked branch was removed.

spring.cloud.config.server.git.environment

  

spring.cloud.config.server.git.force-pull

false

Flag to indicate that the repository should force pull. If true discard any local changes and take from remote repository.

spring.cloud.config.server.git.git-credentials-provider

 

The credentials provider to use to connect to the Git repository.

spring.cloud.config.server.git.git-factory

  

spring.cloud.config.server.git.host-key

  

spring.cloud.config.server.git.host-key-algorithm

  

spring.cloud.config.server.git.ignore-local-ssh-settings

false

 

spring.cloud.config.server.git.known-hosts-file

  

spring.cloud.config.server.git.last-refresh

0

Time of the last refresh of the git repository

spring.cloud.config.server.git.order

  

spring.cloud.config.server.git.passphrase

 

Passphrase for unlocking your ssh private key.

spring.cloud.config.server.git.password

 

Password for authentication with remote repository.

spring.cloud.config.server.git.preferred-authentications

  

spring.cloud.config.server.git.private-key

  

spring.cloud.config.server.git.proxy-host

  

spring.cloud.config.server.git.proxy-port

  

spring.cloud.config.server.git.refresh-rate

0

Time (in seconds) between refresh of the git repository

spring.cloud.config.server.git.repos

 

Map of repository identifier to location and other properties.

spring.cloud.config.server.git.search-paths

 

Search paths to use within local working copy. By default searches only the root.

spring.cloud.config.server.git.strict-host-key-checking

true

Reject incoming SSH host keys from remote servers not in the known host list.

spring.cloud.config.server.git.timeout

5

Timeout (in seconds) for obtaining HTTP or SSH connection (if applicable). Default 5 seconds.

spring.cloud.config.server.git.transport-config-callback

 

Transport configuration callback for JGit commands.

spring.cloud.config.server.git.uri

 

URI of remote repository.

spring.cloud.config.server.git.username

 

Username for authentication with remote repository.

spring.cloud.config.server.health.repositories

  

spring.cloud.config.server.jdbc.order

0

 

spring.cloud.config.server.jdbc.sql

SELECT KEY, VALUE from PROPERTIES where APPLICATION=? and PROFILE=? and LABEL=?

 

spring.cloud.config.server.native.add-label-locations

true

Flag to determine whether label locations should be added.

spring.cloud.config.server.native.default-label

master

 

spring.cloud.config.server.native.fail-on-error

false

Flag to determine how to handle exceptions during decryption (default false).

spring.cloud.config.server.native.order

  

spring.cloud.config.server.native.search-locations

[]

Locations to search for configuration files. Defaults to the same as a Spring Boot app so [classpath:/,classpath:/config/,file:./,file:./config/].

spring.cloud.config.server.native.version

 

Version string to be reported for native repository

spring.cloud.config.server.overrides

 

Extra map for a property source to be sent to all clients unconditionally.

spring.cloud.config.server.prefix

 

Prefix for configuration resource paths (default is empty). Useful when embedding in another application when you don’t want to change the context path or servlet path.

spring.cloud.config.server.strip-document-from-yaml

true

Flag to indicate that YAML documents that are text or collections (not a map) should be returned in "native" form.

spring.cloud.config.server.svn.basedir

 

Base directory for local working copy of repository.

spring.cloud.config.server.svn.default-label

trunk

The default label for environment properties requests.

spring.cloud.config.server.svn.environment

  

spring.cloud.config.server.svn.order

  

spring.cloud.config.server.svn.passphrase

 

Passphrase for unlocking your ssh private key.

spring.cloud.config.server.svn.password

 

Password for authentication with remote repository.

spring.cloud.config.server.svn.search-paths

 

Search paths to use within local working copy. By default searches only the root.

spring.cloud.config.server.svn.strict-host-key-checking

true

Reject incoming SSH host keys from remote servers not in the known host list.

spring.cloud.config.server.svn.uri

 

URI of remote repository.

spring.cloud.config.server.svn.username

 

Username for authentication with remote repository.

spring.cloud.config.server.vault.order

  

spring.cloud.config.token

 

Security Token passed thru to underlying environment repository.

spring.cloud.config.uri

http://localhost:8888

The URI of the remote server (default http://localhost:8888).

spring.cloud.config.username

 

The username to use (HTTP Basic) when contacting the remote server.

spring.cloud.consul.config.acl-token

  

spring.cloud.consul.config.data-key

data

If format is Format.PROPERTIES or Format.YAML then the following field is used as key to look up consul for configuration.

spring.cloud.consul.config.default-context

application

 

spring.cloud.consul.config.enabled

true

 

spring.cloud.consul.config.fail-fast

true

Throw exceptions during config lookup if true, otherwise, log warnings.

spring.cloud.consul.config.format

  

spring.cloud.consul.config.name

 

Alternative to spring.application.name to use in looking up values in consul KV.

spring.cloud.consul.config.prefix

config

 

spring.cloud.consul.config.profile-separator

,

 

spring.cloud.consul.config.watch.delay

1000

The value of the fixed delay for the watch in millis. Defaults to 1000.

spring.cloud.consul.config.watch.enabled

true

If the watch is enabled. Defaults to true.

spring.cloud.consul.config.watch.wait-time

55

The number of seconds to wait (or block) for watch query, defaults to 55. Needs to be less than default ConsulClient (defaults to 60). To increase ConsulClient timeout create a ConsulClient bean with a custom ConsulRawClient with a custom HttpClient.

spring.cloud.consul.discovery.acl-token

  

spring.cloud.consul.discovery.catalog-services-watch-delay

10

 

spring.cloud.consul.discovery.catalog-services-watch-timeout

2

 

spring.cloud.consul.discovery.datacenters

 

Map of serviceId’s → datacenter to query for in server list. This allows looking up services in another datacenters.

spring.cloud.consul.discovery.default-query-tag

 

Tag to query for in service list if one is not listed in serverListQueryTags.

spring.cloud.consul.discovery.default-zone-metadata-name

zone

Service instance zone comes from metadata. This allows changing the metadata tag name.

spring.cloud.consul.discovery.deregister

true

Disable automatic de-registration of service in consul.

spring.cloud.consul.discovery.enabled

true

Is service discovery enabled?

spring.cloud.consul.discovery.fail-fast

true

Throw exceptions during service registration if true, otherwise, log warnings (defaults to true).

spring.cloud.consul.discovery.health-check-critical-timeout

 

Timeout to deregister services critical for longer than timeout (e.g. 30m). Requires consul version 7.x or higher.

spring.cloud.consul.discovery.health-check-interval

10s

How often to perform the health check (e.g. 10s), defaults to 10s.

spring.cloud.consul.discovery.health-check-path

/health

Alternate server path to invoke for health checking

spring.cloud.consul.discovery.health-check-timeout

 

Timeout for health check (e.g. 10s).

spring.cloud.consul.discovery.health-check-tls-skip-verify

 

Skips certificate verification during service checks if true, otherwise runs certificate verification.

spring.cloud.consul.discovery.health-check-url

 

Custom health check url to override default

spring.cloud.consul.discovery.heartbeat.enabled

false

 

spring.cloud.consul.discovery.heartbeat.heartbeat-interval

  

spring.cloud.consul.discovery.heartbeat.interval-ratio

  

spring.cloud.consul.discovery.heartbeat.ttl-unit

s

 

spring.cloud.consul.discovery.heartbeat.ttl-value

30

 

spring.cloud.consul.discovery.hostname

 

Hostname to use when accessing server

spring.cloud.consul.discovery.instance-group

 

Service instance group

spring.cloud.consul.discovery.instance-id

 

Unique service instance id

spring.cloud.consul.discovery.instance-zone

 

Service instance zone

spring.cloud.consul.discovery.ip-address

 

IP address to use when accessing service (must also set preferIpAddress to use)

spring.cloud.consul.discovery.lifecycle.enabled

true

 

spring.cloud.consul.discovery.management-port

 

Port to register the management service under (defaults to management port)

spring.cloud.consul.discovery.management-suffix

management

Suffix to use when registering management service

spring.cloud.consul.discovery.management-tags

 

Tags to use when registering management service

spring.cloud.consul.discovery.port

 

Port to register the service under (defaults to listening port)

spring.cloud.consul.discovery.prefer-agent-address

false

Source of how we will determine the address to use

spring.cloud.consul.discovery.prefer-ip-address

false

Use ip address rather than hostname during registration

spring.cloud.consul.discovery.query-passing

false

Add the 'passing` parameter to /v1/health/service/serviceName. This pushes health check passing to the server.

spring.cloud.consul.discovery.register

true

Register as a service in consul.

spring.cloud.consul.discovery.register-health-check

true

Register health check in consul. Useful during development of a service.

spring.cloud.consul.discovery.scheme

http

Whether to register an http or https service

spring.cloud.consul.discovery.server-list-query-tags

 

Map of serviceId’s → tag to query for in server list. This allows filtering services by a single tag.

spring.cloud.consul.discovery.service-name

 

Service name

spring.cloud.consul.discovery.tags

 

Tags to use when registering service

spring.cloud.consul.enabled

true

Is spring cloud consul enabled

spring.cloud.consul.host

localhost

Consul agent hostname. Defaults to 'localhost'.

spring.cloud.consul.port

8500

Consul agent port. Defaults to '8500'.

spring.cloud.consul.retry.initial-interval

1000

Initial retry interval in milliseconds.

spring.cloud.consul.retry.max-attempts

6

Maximum number of attempts.

spring.cloud.consul.retry.max-interval

2000

Maximum interval for backoff.

spring.cloud.consul.retry.multiplier

1.1

Multiplier for next interval.

spring.cloud.consul.tls.certificate-password

 

Password to open the certificate.

spring.cloud.consul.tls.certificate-path

 

File path to the certificate.

spring.cloud.consul.tls.key-store-instance-type

 

Type of key framework to use.

spring.cloud.consul.tls.key-store-password

 

Password to an external keystore

spring.cloud.consul.tls.key-store-path

 

Path to an external keystore

spring.cloud.discovery.client.composite-indicator.enabled

true

Enables discovery client composite health indicator.

spring.cloud.discovery.client.health-indicator.enabled

true

 

spring.cloud.discovery.client.health-indicator.include-description

true

 

spring.cloud.discovery.client.simple.instances

  

spring.cloud.discovery.client.simple.local.metadata

 

Metadata for the service instance. Can be used by discovery clients to modify their behaviour per instance, e.g. when load balancing.

spring.cloud.discovery.client.simple.local.service-id

 

The identifier or name for the service. Multiple instances might share the same service id.

spring.cloud.discovery.client.simple.local.uri

 

The URI of the service instance. Will be parsed to extract the scheme, hos and port.

spring.cloud.discovery.enabled

true

Enables discovery client health indicators.

spring.cloud.features.enabled

true

Enables the features endpoint.

spring.cloud.gateway.proxy.headers

 

Fixed header values that will be added to all downstream requests.

spring.cloud.gateway.proxy.sensitive

 

A set of sensitive header names that will not be sent downstream by default.

spring.cloud.httpclientfactories.apache.enabled

true

Enables creation of Apache Http Client factory beans.

spring.cloud.httpclientfactories.ok.enabled

true

Enables creation of OK Http Client factory beans.

spring.cloud.hypermedia.refresh.fixed-delay

5000

 

spring.cloud.hypermedia.refresh.initial-delay

10000

 

spring.cloud.inetutils.default-hostname

localhost

The default hostname. Used in case of errors.

spring.cloud.inetutils.default-ip-address

127.0.0.1

The default ipaddress. Used in case of errors.

spring.cloud.inetutils.ignored-interfaces

 

List of Java regex expressions for network interfaces that will be ignored.

spring.cloud.inetutils.preferred-networks

 

List of Java regex expressions for network addresses that will be preferred.

spring.cloud.inetutils.timeout-seconds

1

Timeout in seconds for calculating hostname.

spring.cloud.inetutils.use-only-site-local-interfaces

false

Use only interfaces with site local addresses. See {@link InetAddress#isSiteLocalAddress()} for more details.

spring.cloud.loadbalancer.retry.enabled

true

 

spring.cloud.refresh.enabled

true

Enables autoconfiguration for the refresh scope and associated features.

spring.cloud.service-registry.auto-registration.enabled

true

If Auto-Service Registration is enabled, default to true.

spring.cloud.service-registry.auto-registration.fail-fast

false

Should startup fail if there is no AutoServiceRegistration, default to false.

spring.cloud.service-registry.auto-registration.register-management

true

Whether to register the management as a service, defaults to true

spring.cloud.stream.binders

  

spring.cloud.stream.bindings

  

spring.cloud.stream.consul.binder.event-timeout

5

 

spring.cloud.stream.default-binder

  

spring.cloud.stream.dynamic-destinations

[]

 

spring.cloud.stream.instance-count

1

 

spring.cloud.stream.instance-index

0

 

spring.cloud.stream.integration.message-handler-not-propagated-headers

 

Message header names that will NOT be copied from the inbound message.

spring.cloud.util.enabled

true

Enables creation of Spring Cloud utility beans.

spring.cloud.vault.app-id.app-id-path

app-id

Mount path of the AppId authentication backend.

spring.cloud.vault.app-id.network-interface

 

Network interface hint for the "MAC_ADDRESS" UserId mechanism.

spring.cloud.vault.app-id.user-id

MAC_ADDRESS

UserId mechanism. Can be either "MAC_ADDRESS", "IP_ADDRESS", a string or a class name.

spring.cloud.vault.app-role.app-role-path

approle

Mount path of the AppId authentication backend.

spring.cloud.vault.app-role.role-id

 

The RoleId.

spring.cloud.vault.app-role.secret-id

 

The SecretId.

spring.cloud.vault.application-name

application

Application name for AppId authentication.

spring.cloud.vault.authentication

  

spring.cloud.vault.aws-ec2.aws-ec2-path

aws-ec2

Mount path of the AWS-EC2 authentication backend.

spring.cloud.vault.aws-ec2.identity-document

http://169.254.169.254/latest/dynamic/instance-identity/pkcs7

URL of the AWS-EC2 PKCS7 identity document.

spring.cloud.vault.aws-ec2.nonce

 

Nonce used for AWS-EC2 authentication. An empty nonce defaults to nonce generation.

spring.cloud.vault.aws-ec2.role

 

Name of the role, optional.

spring.cloud.vault.aws-ec2.use-nonce

true

Flag whether to generate and send a nonce. @deprecated not used, will be removed in a future version.

spring.cloud.vault.aws-iam.aws-path

aws

Mount path of the AWS authentication backend.

spring.cloud.vault.aws-iam.role

 

Name of the role, optional. Defaults to the friendly IAM name if not set.

spring.cloud.vault.aws-iam.server-name

 

Name of the server used to set {@code X-Vault-AWS-IAM-Server-ID} header in the headers of login requests.

spring.cloud.vault.aws.access-key-property

cloud.aws.credentials.accessKey

Target property for the obtained access key.

spring.cloud.vault.aws.backend

aws

aws backend path.

spring.cloud.vault.aws.enabled

false

Enable aws backend usage.

spring.cloud.vault.aws.role

 

Role name for credentials.

spring.cloud.vault.aws.secret-key-property

cloud.aws.credentials.secretKey

Target property for the obtained secret key.

spring.cloud.vault.cassandra.backend

cassandra

Cassandra backend path.

spring.cloud.vault.cassandra.enabled

false

Enable cassandra backend usage.

spring.cloud.vault.cassandra.password-property

spring.data.cassandra.password

Target property for the obtained password.

spring.cloud.vault.cassandra.role

 

Role name for credentials.

spring.cloud.vault.cassandra.username-property

spring.data.cassandra.username

Target property for the obtained username.

spring.cloud.vault.config.lifecycle

  

spring.cloud.vault.config.order

0

Used to set a {@link org.springframework.core.env.PropertySource} priority. This is useful to use Vault as an override on other property sources. @see org.springframework.core.PriorityOrdered

spring.cloud.vault.connection-timeout

5000

Connection timeout;

spring.cloud.vault.consul.backend

consul

Consul backend path.

spring.cloud.vault.consul.enabled

false

Enable consul backend usage.

spring.cloud.vault.consul.role

 

Role name for credentials.

spring.cloud.vault.consul.token-property

spring.cloud.consul.token

Target property for the obtained token.

spring.cloud.vault.discovery.enabled

false

Flag to indicate that Vault server discovery is enabled (vault server URL will be looked up via discovery).

spring.cloud.vault.discovery.service-id

vault

Service id to locate Vault.

spring.cloud.vault.enabled

true

Enable Vault config server.

spring.cloud.vault.fail-fast

false

Fail fast if data cannot be obtained from Vault.

spring.cloud.vault.generic.application-name

application

Application name to be used for the context.

spring.cloud.vault.generic.backend

secret

Name of the default backend.

spring.cloud.vault.generic.default-context

application

Name of the default context.

spring.cloud.vault.generic.enabled

true

Enable the generic backend.

spring.cloud.vault.generic.profile-separator

/

Profile-separator to combine application name and profile.

spring.cloud.vault.host

localhost

Vault server host.

spring.cloud.vault.kubernetes.kubernetes-path

kubernetes

Mount path of the Kubernetes authentication backend.

spring.cloud.vault.kubernetes.role

 

Name of the role against which the login is being attempted.

spring.cloud.vault.kubernetes.service-account-token-file

/var/run/secrets/kubernetes.io/serviceaccount/token

Path to the service account token file.

spring.cloud.vault.mongodb.backend

mongodb

Cassandra backend path.

spring.cloud.vault.mongodb.enabled

false

Enable mongodb backend usage.

spring.cloud.vault.mongodb.password-property

spring.data.mongodb.password

Target property for the obtained password.

spring.cloud.vault.mongodb.role

 

Role name for credentials.

spring.cloud.vault.mongodb.username-property

spring.data.mongodb.username

Target property for the obtained username.

spring.cloud.vault.mysql.backend

mysql

mysql backend path.

spring.cloud.vault.mysql.enabled

false

Enable mysql backend usage.

spring.cloud.vault.mysql.password-property

spring.datasource.password

Target property for the obtained username.

spring.cloud.vault.mysql.role

 

Role name for credentials.

spring.cloud.vault.mysql.username-property

spring.datasource.username

Target property for the obtained username.

spring.cloud.vault.port

8200

Vault server port.

spring.cloud.vault.postgresql.backend

postgresql

postgresql backend path.

spring.cloud.vault.postgresql.enabled

false

Enable postgresql backend usage.

spring.cloud.vault.postgresql.password-property

spring.datasource.password

Target property for the obtained username.

spring.cloud.vault.postgresql.role

 

Role name for credentials.

spring.cloud.vault.postgresql.username-property

spring.datasource.username

Target property for the obtained username.

spring.cloud.vault.rabbitmq.backend

rabbitmq

rabbitmq backend path.

spring.cloud.vault.rabbitmq.enabled

false

Enable rabbitmq backend usage.

spring.cloud.vault.rabbitmq.password-property

spring.rabbitmq.password

Target property for the obtained password.

spring.cloud.vault.rabbitmq.role

 

Role name for credentials.

spring.cloud.vault.rabbitmq.username-property

spring.rabbitmq.username

Target property for the obtained username.

spring.cloud.vault.read-timeout

15000

Read timeout;

spring.cloud.vault.scheme

https

Protocol scheme. Can be either "http" or "https".

spring.cloud.vault.ssl.cert-auth-path

cert

Mount path of the TLS cert authentication backend.

spring.cloud.vault.ssl.key-store

 

Trust store that holds certificates and private keys.

spring.cloud.vault.ssl.key-store-password

 

Password used to access the key store.

spring.cloud.vault.ssl.trust-store

 

Trust store that holds SSL certificates.

spring.cloud.vault.ssl.trust-store-password

 

Password used to access the trust store.

spring.cloud.vault.token

 

Static vault token. Required if {@link #authentication} is {@code TOKEN}.

spring.cloud.vault.uri

 

Vault URI. Can be set with scheme, host and port.

spring.cloud.zookeeper.base-sleep-time-ms

50

Initial amount of time to wait between retries

spring.cloud.zookeeper.block-until-connected-unit

 

The unit of time related to blocking on connection to Zookeeper

spring.cloud.zookeeper.block-until-connected-wait

10

Wait time to block on connection to Zookeeper

spring.cloud.zookeeper.connect-string

localhost:2181

Connection string to the Zookeeper cluster

spring.cloud.zookeeper.default-health-endpoint

 

Default health endpoint that will be checked to verify that a dependency is alive

spring.cloud.zookeeper.dependencies

 

Mapping of alias to ZookeeperDependency. From Ribbon perspective the alias is actually serviceID since Ribbon can’t accept nested structures in serviceID

spring.cloud.zookeeper.dependency-configurations

  

spring.cloud.zookeeper.dependency-names

  

spring.cloud.zookeeper.discovery.enabled

true

 

spring.cloud.zookeeper.discovery.initial-status

 

The initial status of this instance (defaults to {@link StatusConstants#STATUS_UP}).

spring.cloud.zookeeper.discovery.instance-host

 

Predefined host with which a service can register itself in Zookeeper. Corresponds to the {code address} from the URI spec.

spring.cloud.zookeeper.discovery.instance-id

 

Id used to register with zookeeper. Defaults to a random UUID.

spring.cloud.zookeeper.discovery.instance-port

 

Port to register the service under (defaults to listening port)

spring.cloud.zookeeper.discovery.instance-ssl-port

 

Ssl port of the registered service.

spring.cloud.zookeeper.discovery.metadata

 

Gets the metadata name/value pairs associated with this instance. This information is sent to zookeeper and can be used by other instances.

spring.cloud.zookeeper.discovery.register

true

Register as a service in zookeeper.

spring.cloud.zookeeper.discovery.root

/services

Root Zookeeper folder in which all instances are registered

spring.cloud.zookeeper.discovery.uri-spec

{scheme}://{address}:{port}

The URI specification to resolve during service registration in Zookeeper

spring.cloud.zookeeper.enabled

true

Is Zookeeper enabled

spring.cloud.zookeeper.max-retries

10

Max number of times to retry

spring.cloud.zookeeper.max-sleep-ms

500

Max time in ms to sleep on each retry

spring.cloud.zookeeper.prefix

 

Common prefix that will be applied to all Zookeeper dependencies' paths

spring.integration.poller.fixed-delay

1000

Fixed delay for default poller.

spring.integration.poller.max-messages-per-poll

1

Maximum messages per poll for the default poller.

spring.sleuth.annotation.enabled

true

 

spring.sleuth.async.configurer.enabled

true

Enable default AsyncConfigurer.

spring.sleuth.async.enabled

true

Enable instrumenting async related components so that the tracing information is passed between threads.

spring.sleuth.enabled

true

 

spring.sleuth.feign.enabled

true

Enable span information propagation when using Feign.

spring.sleuth.feign.processor.enabled

true

Enable post processor that wraps Feign Context in its tracing representations.

spring.sleuth.hystrix.strategy.enabled

true

Enable custom HystrixConcurrencyStrategy that wraps all Callable instances into their Sleuth representative - the TraceCallable.

spring.sleuth.integration.enabled

true

Enable Spring Integration sleuth instrumentation.

spring.sleuth.integration.patterns

*

An array of simple patterns against which channel names will be matched. Default is * (all channels). See org.springframework.util.PatternMatchUtils.simpleMatch(String, String).

spring.sleuth.integration.websockets.enabled

true

Enable tracing for WebSockets.

spring.sleuth.keys.async.class-name-key

class

Simple name of the class with a method annotated with {@code @Async} from which the asynchronous process started @see org.springframework.scheduling.annotation.Async

spring.sleuth.keys.async.method-name-key

method

Name of the method annotated with {@code @Async} @see org.springframework.scheduling.annotation.Async

spring.sleuth.keys.async.prefix

 

Prefix for header names if they are added as tags.

spring.sleuth.keys.async.thread-name-key

thread

Name of the thread that executed the async method @see org.springframework.scheduling.annotation.Async

spring.sleuth.keys.http.headers

 

Additional headers that should be added as tags if they exist. If the header value is multi-valued, the tag value will be a comma-separated, single-quoted list.

spring.sleuth.keys.http.host

http.host

The domain portion of the URL or host header. Example: "mybucket.s3.amazonaws.com". Used to filter by host as opposed to ip address.

spring.sleuth.keys.http.method

http.method

The HTTP method, or verb, such as "GET" or "POST". Used to filter against an http route.

spring.sleuth.keys.http.path

http.path

The absolute http path, without any query parameters. Example: "/objects/abcd-ff". Used to filter against an http route, portably with zipkin v1. In zipkin v1, only equals filters are supported. Dropping query parameters makes the number of distinct URIs less. For example, one can query for the same resource, regardless of signing parameters encoded in the query line. This does not reduce cardinality to a HTTP single route. For example, it is common to express a route as an http URI template like "/resource/{resource_id}". In systems where only equals queries are available, searching for {@code http.uri=/resource} won’t match if the actual request was "/resource/abcd-ff". Historical note: This was commonly expressed as "http.uri" in zipkin, eventhough it was most often just a path.

spring.sleuth.keys.http.prefix

http.

Prefix for header names if they are added as tags.

spring.sleuth.keys.http.request-size

http.request.size

The size of the non-empty HTTP request body, in bytes. Ex. "16384" <p>Large uploads can exceed limits or contribute directly to latency.

spring.sleuth.keys.http.response-size

http.response.size

The size of the non-empty HTTP response body, in bytes. Ex. "16384" <p>Large downloads can exceed limits or contribute directly to latency.

spring.sleuth.keys.http.status-code

http.status_code

The HTTP response code, when not in 2xx range. Ex. "503" Used to filter for error status. 2xx range are not logged as success codes are less interesting for latency troubleshooting. Omitting saves at least 20 bytes per span.

spring.sleuth.keys.http.url

http.url

The entire URL, including the scheme, host and query parameters if available. Ex. "https://mybucket.s3.amazonaws.com/objects/abcd-ff?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Algorithm=AWS4-HMAC-SHA256…​" Combined with {@link #method}, you can understand the fully-qualified request line. This is optional as it may include private data or be of considerable length.

spring.sleuth.keys.hystrix.command-group

commandGroup

Name of the command group. Hystrix uses the command group key to group together commands such as for reporting, alerting, dashboards, or team/library ownership. @see com.netflix.hystrix.HystrixCommandGroupKey

spring.sleuth.keys.hystrix.command-key

commandKey

Name of the command key. Describes the name for the given command. A key to represent a {@link com.netflix.hystrix.HystrixCommand} for monitoring, circuit-breakers, metrics publishing, caching and other such uses. @see com.netflix.hystrix.HystrixCommandKey

spring.sleuth.keys.hystrix.prefix

 

Prefix for header names if they are added as tags.

spring.sleuth.keys.hystrix.thread-pool-key

threadPoolKey

Name of the thread pool key. The thread-pool key represents a {@link com.netflix.hystrix.HystrixThreadPool} for monitoring, metrics publishing, caching, and other such uses. A {@link com.netflix.hystrix.HystrixCommand} is associated with a single {@link com.netflix.hystrix.HystrixThreadPool} as retrieved by the {@link com.netflix.hystrix.HystrixThreadPoolKey} injected into it, or it defaults to one created using the {@link com.netflix.hystrix.HystrixCommandGroupKey} it is created with. @see com.netflix.hystrix.HystrixThreadPoolKey

spring.sleuth.keys.message.headers

 

Additional headers that should be added as tags if they exist. If the header value is not a String it will be converted to a String using its toString() method.

spring.sleuth.keys.message.payload.size

message/payload-size

An estimate of the size of the payload if available.

spring.sleuth.keys.message.payload.type

message/payload-type

The type of the payload.

spring.sleuth.keys.message.prefix

message/

Prefix for header names if they are added as tags.

spring.sleuth.keys.mvc.controller-class

mvc.controller.class

The lower case, hyphen delimited name of the class that processes the request. Ex. class named "BookController" will result in "book-controller" tag value.

spring.sleuth.keys.mvc.controller-method

mvc.controller.method

The lower case, hyphen delimited name of the class that processes the request. Ex. method named "listOfBooks" will result in "list-of-books" tag value.

spring.sleuth.log.slf4j.enabled

true

Enable a {@link Slf4jSpanLogger} that prints tracing information in the logs.

spring.sleuth.log.slf4j.name-skip-pattern

 

Name pattern for which span should not be printed in the logs.

spring.sleuth.metric.enabled

true

Enable calculation of accepted and dropped spans through {@link org.springframework.boot.actuate.metrics.CounterService}

spring.sleuth.metric.span.accepted-name

counter.span.accepted

 

spring.sleuth.metric.span.dropped-name

counter.span.dropped

 

spring.sleuth.rxjava.schedulers.hook.enabled

true

Enable support for RxJava via RxJavaSchedulersHook.

spring.sleuth.rxjava.schedulers.ignoredthreads

[HystrixMetricPoller, ^RxComputation.*$]

Thread names for which spans will not be sampled.

spring.sleuth.sampler.percentage

0.1

Percentage of requests that should be sampled. E.g. 1.0 - 100% requests should be sampled. The precision is whole-numbers only (i.e. there’s no support for 0.1% of the traces).

spring.sleuth.scheduled.enabled

true

Enable tracing for {@link org.springframework.scheduling.annotation.Scheduled}.

spring.sleuth.scheduled.skip-pattern

 

Pattern for the fully qualified name of a class that should be skipped.

spring.sleuth.supports-join

true

When true, your tracing system allows sharing a span ID between a client and server span

spring.sleuth.trace-id128

false

When true, generate 128-bit trace IDs instead of 64-bit ones.

spring.sleuth.web.client.enabled

true

Enable interceptor injecting into {@link org.springframework.web.client.RestTemplate}

spring.sleuth.web.enabled

true

When true enables instrumentation for web applications

spring.sleuth.web.filter-order

 

Order in which the {@link TraceFilter} should be registered. Defaults to {@link TraceFilter#ORDER}

spring.sleuth.web.skip-pattern

/api-docs.*

/autoconfig

/configprops

/dump

/health

/info

/metrics.*

/mappings

/trace

/swagger.*

.*\.png

.*\.css

.*\.js

.*\.html

/favicon.ico

/hystrix.stream

Pattern for URLs that should be skipped in tracing

spring.sleuth.zuul.enabled

true

Enable span information propagation when using Zuul.

stubrunner.classifier

stubs

The classifier to use by default in ivy co-ordinates for a stub.

stubrunner.consumer-name

 

You can override the default {@code spring.application.name} of this field by setting a value to this parameter.

stubrunner.ids

[]

The ids of the stubs to run in "ivy" notation ([groupId]:artifactId:[version]:[classifier][:port]). {@code groupId}, {@code classifier}, {@code version} and {@code port} can be optional.

stubrunner.ids-to-service-ids

 

Mapping of Ivy notation based ids to serviceIds inside your application Example "a:b" → "myService" "artifactId" → "myOtherService"

stubrunner.mappings-output-folder

 

Dumps the mappings of each HTTP server to the selected folder

stubrunner.max-port

15000

Max value of a port for the automatically started WireMock server

stubrunner.min-port

10000

Min value of a port for the automatically started WireMock server

stubrunner.password

 

Repository password

stubrunner.proxy-host

 

Repository proxy host

stubrunner.proxy-port

 

Repository proxy port

stubrunner.repository-root

 

The repository root to use (where the stubs should be downloaded from)

stubrunner.stubs-per-consumer

false

Should only stubs for this particular consumer get registered in HTTP server stub.

stubrunner.username

 

Repository username

stubrunner.work-offline

false

Should the stubs be checked for presence only locally

turbine.stream.enabled

true

Enables Autoconfiguration for a Spring Cloud Turbine using Spring Cloud Stream.

zuul.add-host-header

false

Flag to determine whether the proxy forwards the Host header.

zuul.add-proxy-headers

true

Flag to determine whether the proxy adds X-Forwarded-* headers.

zuul.force-original-query-string-encoding

false

Flag to force the original query string encoding when building the backend URI in SimpleHostRoutingFilter. When activated, query string will be built using HttpServletRequest getQueryString() method instead of UriTemplate. Note that this flag is not used in RibbonRoutingFilter with services found via DiscoveryClient (like Eureka).

zuul.host.connect-timeout-millis

2000

The connection timeout in millis. Defaults to 2000.

zuul.host.max-per-route-connections

20

The maximum number of connections that can be used by a single route.

zuul.host.max-total-connections

200

The maximum number of total connections the proxy can hold open to backends.

zuul.host.socket-timeout-millis

10000

The socket timeout in millis. Defaults to 10000.

zuul.host.time-to-live

-1

The lifetime for the connection pool.

zuul.host.time-unit

 

The time unit for timeToLive.

zuul.ignore-local-service

true

 

zuul.ignore-security-headers

true

Flag to say that SECURITY_HEADERS are added to ignored headers if spring security is on the classpath. By setting ignoreSecurityHeaders to false we can switch off this default behaviour. This should be used together with disabling the default spring security headers see https://docs.spring.io/spring-security/site/docs/current/reference/html/headers.html#default-security-headers

zuul.ignored-headers

 

Names of HTTP headers to ignore completely (i.e. leave them out of downstream requests and drop them from downstream responses).

zuul.ignored-patterns

  

zuul.ignored-services

 

Set of service names not to consider for proxying automatically. By default all services in the discovery client will be proxied.

zuul.include-debug-header

false

Setting for SendResponseFilter to conditionally include X-Zuul-Debug-Header header.

zuul.initial-stream-buffer-size

8192

Setting for SendResponseFilter for the initial stream buffer size.

zuul.prefix

 

A common prefix for all routes.

zuul.remove-semicolon-content

true

Flag to say that path elements past the first semicolon can be dropped.

zuul.retryable

false

Flag for whether retry is supported by default (assuming the routes themselves support it).

zuul.ribbon-isolation-strategy

  

zuul.ribbon.eager-load.enabled

false

Enables eager loading of Ribbon clients on startup.

zuul.routes

 

Map of route names to properties.

zuul.semaphore.max-semaphores

100

The maximum number of total semaphores for Hystrix.

zuul.sensitive-headers

 

List of sensitive headers that are not passed to downstream requests. Defaults to a "safe" set of headers that commonly contain user credentials. It’s OK to remove those from the list if the downstream service is part of the same system as the proxy, so they are sharing authentication data. If using a physical URL outside your own domain, then generally it would be a bad idea to leak user credentials.

zuul.servlet-path

/zuul

Path to install Zuul as a servlet (not part of Spring MVC). The servlet is more memory efficient for requests with large bodies, e.g. file uploads.

zuul.set-content-length

false

Setting for SendResponseFilter to conditionally set Content-Length header.

zuul.ssl-hostname-validation-enabled

true

Flag to say whether the hostname for ssl connections should be verified or not. Default is true. This should only be used in test setups!

zuul.strip-prefix

true

Flag saying whether to strip the prefix from the path before forwarding.

zuul.thread-pool.thread-pool-key-prefix

 

A prefix for HystrixThreadPoolKey of hystrix’s thread pool that is allocated to each service Id. This property is only applicable when using THREAD as ribbonIsolationStrategy and useSeparateThreadPools = true

zuul.thread-pool.use-separate-thread-pools

false

Flag to determine whether RibbonCommands should use separate thread pools for hystrix. By setting to true, RibbonCommands will be executed in a hystrix’s thread pool that it is associated with. Each RibbonCommand will be associated with a thread pool according to its commandKey (serviceId). As default, all commands will be executed in a single thread pool whose threadPoolKey is "RibbonCommand". This property is only applicable when using THREAD as ribbonIsolationStrategy

zuul.trace-request-body

true

Flag to say that request bodies can be traced.

Prev   
115. Serverless Platform Adapters Home 
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42. Application Context ID must be unique
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42. Application Context ID must be unique

The bus tries to eliminate processing an event twice, once from the original ApplicationEvent and once from the queue. To do this, it checks the sending application context id againts the current application context id. If multiple instances of a service have the same application context id, events will not be processed. Running on a local machine, each service will be on a different port and that will be part of the application context id. Cloud Foundry supplies an index to differentiate. To ensure that the application context id is the unique, set spring.application.index to something unique for each instance of a service. For example, in lattice, set spring.application.index=${INSTANCE_INDEX} in application.properties (or bootstrap.properties if using configserver).

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41. Addressing all instances of a service Home 43. Customizing the Message Broker
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Part V. Binder Implementations
Prev   Next

Part V. Binder Implementations

Prev   Next
36. Getting Started Home 37. Apache Kafka Binder
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27. Binders
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27. Binders

Spring Cloud Stream provides a Binder abstraction for use in connecting to physical destinations at the external middleware. +This section provides information about the main concepts behind the Binder SPI, its main components, and implementation-specific details.

27.1 Producers and Consumers

Figure 27.1. Producers and Consumers

producers consumers

A producer is any component that sends messages to a channel. +The channel can be bound to an external message broker via a Binder implementation for that broker. +When invoking the bindProducer() method, the first parameter is the name of the destination within the broker, the second parameter is the local channel instance to which the producer will send messages, and the third parameter contains properties (such as a partition key expression) to be used within the adapter that is created for that channel.

A consumer is any component that receives messages from a channel. +As with a producer, the consumer’s channel can be bound to an external message broker. +When invoking the bindConsumer() method, the first parameter is the destination name, and a second parameter provides the name of a logical group of consumers. +Each group that is represented by consumer bindings for a given destination receives a copy of each message that a producer sends to that destination (i.e., publish-subscribe semantics). +If there are multiple consumer instances bound using the same group name, then messages will be load-balanced across those consumer instances so that each message sent by a producer is consumed by only a single consumer instance within each group (i.e., queueing semantics).

27.2 Binder SPI

The Binder SPI consists of a number of interfaces, out-of-the box utility classes and discovery strategies that provide a pluggable mechanism for connecting to external middleware.

The key point of the SPI is the Binder interface which is a strategy for connecting inputs and outputs to external middleware.

public interface Binder<T, C extends ConsumerProperties, P extends ProducerProperties> {
+	Binding<T> bindConsumer(String name, String group, T inboundBindTarget, C consumerProperties);
+
+	Binding<T> bindProducer(String name, T outboundBindTarget, P producerProperties);
+}

The interface is parameterized, offering a number of extension points:

  • input and output bind targets - as of version 1.0, only MessageChannel is supported, but this is intended to be used as an extension point in the future;
  • extended consumer and producer properties - allowing specific Binder implementations to add supplemental properties which can be supported in a type-safe manner.

A typical binder implementation consists of the following

  • a class that implements the Binder interface;
  • a Spring @Configuration class that creates a bean of the type above along with the middleware connection infrastructure;
  • a META-INF/spring.binders file found on the classpath containing one or more binder definitions, e.g.
kafka:\
+org.springframework.cloud.stream.binder.kafka.config.KafkaBinderConfiguration

27.3 Binder Detection

Spring Cloud Stream relies on implementations of the Binder SPI to perform the task of connecting channels to message brokers. +Each Binder implementation typically connects to one type of messaging system.

27.3.1 Classpath Detection

By default, Spring Cloud Stream relies on Spring Boot’s auto-configuration to configure the binding process. +If a single Binder implementation is found on the classpath, Spring Cloud Stream will use it automatically. +For example, a Spring Cloud Stream project that aims to bind only to RabbitMQ can simply add the following dependency:

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-rabbit</artifactId>
+</dependency>

For the specific maven coordinates of other binder dependencies, please refer to the documentation of that binder implementation.

27.4 Multiple Binders on the Classpath

When multiple binders are present on the classpath, the application must indicate which binder is to be used for each channel binding. +Each binder configuration contains a META-INF/spring.binders, which is a simple properties file:

rabbit:\
+org.springframework.cloud.stream.binder.rabbit.config.RabbitServiceAutoConfiguration

Similar files exist for the other provided binder implementations (e.g., Kafka), and custom binder implementations are expected to provide them, as well. +The key represents an identifying name for the binder implementation, whereas the value is a comma-separated list of configuration classes that each contain one and only one bean definition of type org.springframework.cloud.stream.binder.Binder.

Binder selection can either be performed globally, using the spring.cloud.stream.defaultBinder property (e.g., spring.cloud.stream.defaultBinder=rabbit) or individually, by configuring the binder on each channel binding. +For instance, a processor application (that has channels with the names input and output for read/write respectively) which reads from Kafka and writes to RabbitMQ can specify the following configuration:

spring.cloud.stream.bindings.input.binder=kafka
+spring.cloud.stream.bindings.output.binder=rabbit

27.5 Connecting to Multiple Systems

By default, binders share the application’s Spring Boot auto-configuration, so that one instance of each binder found on the classpath will be created. +If your application should connect to more than one broker of the same type, you can specify multiple binder configurations, each with different environment settings.

[Note]Note

Turning on explicit binder configuration will disable the default binder configuration process altogether. +If you do this, all binders in use must be included in the configuration. +Frameworks that intend to use Spring Cloud Stream transparently may create binder configurations that can be referenced by name, but will not affect the default binder configuration. +In order to do so, a binder configuration may have its defaultCandidate flag set to false, e.g. spring.cloud.stream.binders.<configurationName>.defaultCandidate=false. +This denotes a configuration that will exist independently of the default binder configuration process.

For example, this is the typical configuration for a processor application which connects to two RabbitMQ broker instances:

spring:
+  cloud:
+    stream:
+      bindings:
+        input:
+          destination: foo
+          binder: rabbit1
+        output:
+          destination: bar
+          binder: rabbit2
+      binders:
+        rabbit1:
+          type: rabbit
+          environment:
+            spring:
+              rabbitmq:
+                host: <host1>
+        rabbit2:
+          type: rabbit
+          environment:
+            spring:
+              rabbitmq:
+                host: <host2>

27.6 Binder configuration properties

The following properties are available when creating custom binder configurations. +They must be prefixed with spring.cloud.stream.binders.<configurationName>.

type

The binder type. +It typically references one of the binders found on the classpath, in particular a key in a META-INF/spring.binders file.

By default, it has the same value as the configuration name.

inheritEnvironment

Whether the configuration will inherit the environment of the application itself.

Default true.

environment

Root for a set of properties that can be used to customize the environment of the binder. +When this is configured, the context in which the binder is being created is not a child of the application context. +This allows for complete separation between the binder components and the application components.

Default empty.

defaultCandidate

Whether the binder configuration is a candidate for being considered a default binder, or can be used only when explicitly referenced. +This allows adding binder configurations without interfering with the default processing.

Default true.

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26. Programming Model Home 28. Configuration Options
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45. Broadcasting Your Own Events
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45. Broadcasting Your Own Events

The Bus can carry any event of type RemoteApplicationEvent, but the +default transport is JSON and the deserializer needs to know which +types are going to be used ahead of time. To register a new type it +needs to be in a subpackage of org.springframework.cloud.bus.event.

To customise the event name you can use @JsonTypeName on your custom class +or rely on the default strategy which is to use the simple name of the class. +Note that both the producer and the consumer will need access to the class +definition.

45.1 Registering events in custom packages

If you cannot or don’t want to use a subpackage of org.springframework.cloud.bus.event +for your custom events, you must specify which packages to scan for events of +type RemoteApplicationEvent using @RemoteApplicationEventScan. Packages +specified with @RemoteApplicationEventScan include subpackages.

For example, if you have a custom event called FooEvent:

package com.acme;
+
+public class FooEvent extends RemoteApplicationEvent {
+    ...
+}

you can register this event with the deserializer in the following way:

package com.acme;
+
+@Configuration
+@RemoteApplicationEventScan
+public class BusConfiguration {
+    ...
+}

Without specifying a value, the package of the class where @RemoteApplicationEventScan +is used will be registered. In this example com.acme will be registered using the +package of BusConfiguration.

You can also explicitly specify the packages to scan using the value, basePackages or +basePackageClasses properties on @RemoteApplicationEventScan. For example:

package com.acme;
+
+@Configuration
+//@RemoteApplicationEventScan({"com.acme", "foo.bar"})
+//@RemoteApplicationEventScan(basePackages = {"com.acme", "foo.bar", "fizz.buzz"})
+@RemoteApplicationEventScan(basePackageClasses = BusConfiguration.class)
+public class BusConfiguration {
+    ...
+}

All examples of @RemoteApplicationEventScan above are equivalent, +in that the com.acme package will be registered by explicitly specifying the +packages on @RemoteApplicationEventScan. Note, you can specify multiple base +packages to scan.

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44. Tracing Bus Events Home Part VII. Spring Cloud Sleuth
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109. Building and Running a Function
Prev Part XV. Spring Cloud Function Next

109. Building and Running a Function

The sample @SpringBootApplication above has a function that can be +decorated at runtime by Spring Cloud Function to be an HTTP endpoint, +or a Stream processor, for instance with RabbitMQ, Apache Kafka or +JMS.

The @Beans can be Function, Consumer or Supplier (all from +java.util), and their parametric types can be String or POJO. A +Function is exposed as a Spring Cloud Stream Processor if +spring-cloud-function-stream is on the classpath. +A Consumer is also exposed as a Stream +Sink and a Supplier translates to a Stream Source. +HTTP endpoints are exposed if the Stream binder is spring-cloud-stream-binder-servlet.

Functions can be of Flux<String> or Flux<Pojo> and Spring Cloud +Function takes care of converting the data to and from the desired +types, as long as it comes in as plain text or (in the case of the +POJO) JSON. TBD: support for Flux<Message<Pojo>> and maybe plain +Pojo types (Fluxes implied and implemented by the framework).

Functions can be grouped together in a single application, or deployed +one-per-jar. It’s up to the developer to choose. An app with multiple +functions can be deployed multiple times in different "personalities", +exposing different functions over different physical transports.

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108. Getting Started Home 110. Function Catalog and Flexible Function Signatures
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13. Circuit Breaker: Hystrix Clients
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13. Circuit Breaker: Hystrix Clients

Netflix has created a library called Hystrix that implements the circuit breaker pattern. In a microservice architecture it is common to have multiple layers of service calls.

Figure 13.1. Microservice Graph

Hystrix

A service failure in the lower level of services can cause cascading failure all the way up to the user. When calls to a particular service is greater than circuitBreaker.requestVolumeThreshold (default: 20 requests) and failue percentage is greater than circuitBreaker.errorThresholdPercentage (default: >50%) in a rolling window defined by metrics.rollingStats.timeInMilliseconds (default: 10 seconds), the circuit opens and the call is not made. In cases of error and an open circuit a fallback can be provided by the developer.

Figure 13.2. Hystrix fallback prevents cascading failures

HystrixFallback

Having an open circuit stops cascading failures and allows overwhelmed or failing services time to heal. The fallback can be another Hystrix protected call, static data or a sane empty value. Fallbacks may be chained so the first fallback makes some other business call which in turn falls back to static data.

13.1 How to Include Hystrix

To include Hystrix in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-hystrix. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

Example boot app:

@SpringBootApplication
+@EnableCircuitBreaker
+public class Application {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}
+
+@Component
+public class StoreIntegration {
+
+    @HystrixCommand(fallbackMethod = "defaultStores")
+    public Object getStores(Map<String, Object> parameters) {
+        //do stuff that might fail
+    }
+
+    public Object defaultStores(Map<String, Object> parameters) {
+        return /* something useful */;
+    }
+}

The @HystrixCommand is provided by a Netflix contrib library called +"javanica". +Spring Cloud automatically wraps Spring beans with that +annotation in a proxy that is connected to the Hystrix circuit +breaker. The circuit breaker calculates when to open and close the +circuit, and what to do in case of a failure.

To configure the @HystrixCommand you can use the commandProperties +attribute with a list of @HystrixProperty annotations. See +here +for more details. See the Hystrix wiki +for details on the properties available.

13.2 Propagating the Security Context or using Spring Scopes

If you want some thread local context to propagate into a @HystrixCommand the default declaration will not work because it executes the command in a thread pool (in case of timeouts). You can switch Hystrix to use the same thread as the caller using some configuration, or directly in the annotation, by asking it to use a different "Isolation Strategy". For example:

@HystrixCommand(fallbackMethod = "stubMyService",
+    commandProperties = {
+      @HystrixProperty(name="execution.isolation.strategy", value="SEMAPHORE")
+    }
+)
+...

The same thing applies if you are using @SessionScope or @RequestScope. You will know when you need to do this because of a runtime exception that says it can’t find the scoped context.

You also have the option to set the hystrix.shareSecurityContext property to true. Doing so will auto configure an Hystrix concurrency strategy plugin hook who will transfer the SecurityContext from your main thread to the one used by the Hystrix command. Hystrix does not allow multiple hystrix concurrency strategy to be registered so an extension mechanism is available by declaring your own HystrixConcurrencyStrategy as a Spring bean. Spring Cloud will lookup for your implementation within the Spring context and wrap it inside its own plugin.

13.3 Health Indicator

The state of the connected circuit breakers are also exposed in the +/health endpoint of the calling application.

{
+    "hystrix": {
+        "openCircuitBreakers": [
+            "StoreIntegration::getStoresByLocationLink"
+        ],
+        "status": "CIRCUIT_OPEN"
+    },
+    "status": "UP"
+}

13.4 Hystrix Metrics Stream

To enable the Hystrix metrics stream include a dependency on spring-boot-starter-actuator. This will expose the /hystrix.stream as a management endpoint.

    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-actuator</artifactId>
+    </dependency>
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12. Service Discovery: Eureka Server Home 14. Circuit Breaker: Hystrix Dashboard
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14. Circuit Breaker: Hystrix Dashboard
Prev Part III. Spring Cloud Netflix Next

14. Circuit Breaker: Hystrix Dashboard

One of the main benefits of Hystrix is the set of metrics it gathers about each HystrixCommand. The Hystrix Dashboard displays the health of each circuit breaker in an efficient manner.

Figure 14.1. Hystrix Dashboard

Hystrix

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13. Circuit Breaker: Hystrix Clients Home 15. Hystrix Timeouts And Ribbon Clients
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98. Client Side Usage
Prev Part XIV. Spring Cloud Vault Next

98. Client Side Usage

To use these features in an application, just build it as a Spring +Boot application that depends on spring-cloud-vault-config (e.g. see +the test cases). Example Maven configuration:

Example 98.1. pom.xml

<parent>
+    <groupId>org.springframework.boot</groupId>
+    <artifactId>spring-boot-starter-parent</artifactId>
+    <version>1.5.4.RELEASE</version>
+    <relativePath /> <!-- lookup parent from repository -->
+</parent>
+
+<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-starter-vault-config</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-test</artifactId>
+        <scope>test</scope>
+    </dependency>
+</dependencies>
+
+<build>
+    <plugins>
+        <plugin>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-maven-plugin</artifactId>
+        </plugin>
+    </plugins>
+</build>
+
+<!-- repositories also needed for snapshots and milestones -->

Then you can create a standard Spring Boot application, like this simple HTTP server:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello World!";
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}

When it runs it will pick up the external configuration from the +default local Vault server on port 8200 if it is running. To modify +the startup behavior you can change the location of the Vault server +using bootstrap.properties (like application.properties but for +the bootstrap phase of an application context), e.g.

Example 98.2. bootstrap.yml

spring.cloud.vault:
+    host: localhost
+    port: 8200
+    scheme: https
+    uri: https://localhost:8200
+    connection-timeout: 5000
+    read-timeout: 15000
+    config:
+        order: -10

  • host sets the hostname of the Vault host. The host name will be used +for SSL certificate validation
  • port sets the Vault port
  • scheme setting the scheme to http will use plain HTTP. +Supported schemes are http and https.
  • uri configure the Vault endpoint with an URI. Takes precedence over host/port/scheme configuration
  • connection-timeout sets the connection timeout in milliseconds
  • read-timeout sets the read timeout in milliseconds
  • config.order sets the order for the property source

Enabling further integrations requires additional dependencies and +configuration. Depending on how you have set up Vault you might need +additional configuration like +SSL and +authentication.

If the application imports the spring-boot-starter-actuator project, the +status of the vault server will be available via the /health endpoint.

The vault health indicator can be enabled or disabled through the +property health.vault.enabled (default true).

98.1 Authentication

Vault requires an authentication mechanism to authorize client requests.

Spring Cloud Vault supports multiple authentication mechanisms to authenticate applications with Vault.

For a quickstart, use the root token printed by the Vault initialization.

Example 98.3. bootstrap.yml

spring.cloud.vault:
+    token: 19aefa97-cccc-bbbb-aaaa-225940e63d76

[Warning]Warning

Consider carefully your security requirements. Static token authentication is fine if you want quickly get started with Vault, but a static token is not protected any further. Any disclosure to unintended parties allows Vault use with the associated token roles.

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97. Quick Start Home 99. Authentication methods
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Part I. Cloud Native Applications
Prev   Next

Part I. Cloud Native Applications

Cloud Native is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development. A related discipline is that of building 12-factor Apps in which development practices are aligned with delivery and operations goals, for instance by using declarative programming and management and monitoring. Spring Cloud facilitates these styles of development in a number of specific ways and the starting point is a set of features that all components in a distributed system either need or need easy access to when required.

Many of those features are covered by Spring Boot, which we build on in Spring Cloud. Some more are delivered by Spring Cloud as two libraries: Spring Cloud Context and Spring Cloud Commons. Spring Cloud Context provides utilities and special services for the ApplicationContext of a Spring Cloud application (bootstrap context, encryption, refresh scope and environment endpoints). Spring Cloud Commons is a set of abstractions and common classes used in different Spring Cloud implementations (eg. Spring Cloud Netflix vs. Spring Cloud Consul).

If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:

Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

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1. Features Home 2. Spring Cloud Context: Application Context Services
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28. Configuration Options
Prev Part IV. Spring Cloud Stream Next

28. Configuration Options

Spring Cloud Stream supports general configuration options as well as configuration for bindings and binders. +Some binders allow additional binding properties to support middleware-specific features.

Configuration options can be provided to Spring Cloud Stream applications via any mechanism supported by Spring Boot. +This includes application arguments, environment variables, and YAML or .properties files.

28.1 Spring Cloud Stream Properties

spring.cloud.stream.instanceCount

The number of deployed instances of an application. +Must be set for partitioning and if using Kafka.

Default: 1.

spring.cloud.stream.instanceIndex
The instance index of the application: a number from 0 to instanceCount-1. +Used for partitioning and with Kafka. +Automatically set in Cloud Foundry to match the application’s instance index.
spring.cloud.stream.dynamicDestinations

A list of destinations that can be bound dynamically (for example, in a dynamic routing scenario). +If set, only listed destinations can be bound.

Default: empty (allowing any destination to be bound).

spring.cloud.stream.defaultBinder

The default binder to use, if multiple binders are configured. +See Multiple Binders on the Classpath.

Default: empty.

spring.cloud.stream.overrideCloudConnectors

This property is only applicable when the cloud profile is active and Spring Cloud Connectors are provided with the application. +If the property is false (the default), the binder will detect a suitable bound service (e.g. a RabbitMQ service bound in Cloud Foundry for the RabbitMQ binder) and will use it for creating connections (usually via Spring Cloud Connectors). +When set to true, this property instructs binders to completely ignore the bound services and rely on Spring Boot properties (e.g. relying on the spring.rabbitmq.* properties provided in the environment for the RabbitMQ binder). +The typical usage of this property is to be nested in a customized environment when connecting to multiple systems.

Default: false.

28.2 Binding Properties

Binding properties are supplied using the format spring.cloud.stream.bindings.<channelName>.<property>=<value>. +The <channelName> represents the name of the channel being configured (e.g., output for a Source).

To avoid repetition, Spring Cloud Stream supports setting values for all channels, in the format spring.cloud.stream.default.<property>=<value>.

In what follows, we indicate where we have omitted the spring.cloud.stream.bindings.<channelName>. prefix and focus just on the property name, with the understanding that the prefix will be included at runtime.

28.2.1 Properties for Use of Spring Cloud Stream

The following binding properties are available for both input and output bindings and must be prefixed with spring.cloud.stream.bindings.<channelName>., e.g. spring.cloud.stream.bindings.input.destination=ticktock.

Default values can be set by using the prefix spring.cloud.stream.default, e.g. spring.cloud.stream.default.contentType=application/json.

destination
The target destination of a channel on the bound middleware (e.g., the RabbitMQ exchange or Kafka topic). +If the channel is bound as a consumer, it could be bound to multiple destinations and the destination names can be specified as comma separated String values. +If not set, the channel name is used instead. +The default value of this property cannot be overridden.
group

The consumer group of the channel. +Applies only to inbound bindings. +See Consumer Groups.

Default: null (indicating an anonymous consumer).

contentType

The content type of the channel.

Default: null (so that no type coercion is performed).

binder

The binder used by this binding. +See Section 27.4, “Multiple Binders on the Classpath” for details.

Default: null (the default binder will be used, if one exists).

28.2.2 Consumer properties

The following binding properties are available for input bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.consumer., e.g. spring.cloud.stream.bindings.input.consumer.concurrency=3.

Default values can be set by using the prefix spring.cloud.stream.default.consumer, e.g. spring.cloud.stream.default.consumer.headerMode=raw.

concurrency

The concurrency of the inbound consumer.

Default: 1.

partitioned

Whether the consumer receives data from a partitioned producer.

Default: false.

headerMode

When set to raw, disables header parsing on input. +Effective only for messaging middleware that does not support message headers natively and requires header embedding. +Useful when inbound data is coming from outside Spring Cloud Stream applications.

Default: embeddedHeaders.

maxAttempts

If processing fails, the number of attempts to process the message (including the first). +Set to 1 to disable retry.

Default: 3.

backOffInitialInterval

The backoff initial interval on retry.

Default: 1000.

backOffMaxInterval

The maximum backoff interval.

Default: 10000.

backOffMultiplier

The backoff multiplier.

Default: 2.0.

instanceIndex

When set to a value greater than equal to zero, allows customizing the instance index of this consumer (if different from spring.cloud.stream.instanceIndex). +When set to a negative value, it will default to spring.cloud.stream.instanceIndex.

Default: -1.

instanceCount

When set to a value greater than equal to zero, allows customizing the instance count of this consumer (if different from spring.cloud.stream.instanceCount). +When set to a negative value, it will default to spring.cloud.stream.instanceCount.

Default: -1.

28.2.3 Producer Properties

The following binding properties are available for output bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.producer., e.g. spring.cloud.stream.bindings.input.producer.partitionKeyExpression=payload.id.

Default values can be set by using the prefix spring.cloud.stream.default.producer, e.g. spring.cloud.stream.default.producer.partitionKeyExpression=payload.id.

partitionKeyExpression

A SpEL expression that determines how to partition outbound data. +If set, or if partitionKeyExtractorClass is set, outbound data on this channel will be partitioned, and partitionCount must be set to a value greater than 1 to be effective. +The two options are mutually exclusive. +See Section 25.5, “Partitioning Support”.

Default: null.

partitionKeyExtractorClass

A PartitionKeyExtractorStrategy implementation. +If set, or if partitionKeyExpression is set, outbound data on this channel will be partitioned, and partitionCount must be set to a value greater than 1 to be effective. +The two options are mutually exclusive. +See Section 25.5, “Partitioning Support”.

Default: null.

partitionSelectorClass

A PartitionSelectorStrategy implementation. +Mutually exclusive with partitionSelectorExpression. +If neither is set, the partition will be selected as the hashCode(key) % partitionCount, where key is computed via either partitionKeyExpression or partitionKeyExtractorClass.

Default: null.

partitionSelectorExpression

A SpEL expression for customizing partition selection. +Mutually exclusive with partitionSelectorClass. +If neither is set, the partition will be selected as the hashCode(key) % partitionCount, where key is computed via either partitionKeyExpression or partitionKeyExtractorClass.

Default: null.

partitionCount

The number of target partitions for the data, if partitioning is enabled. +Must be + set to a value greater than 1 if the producer is partitioned. +On Kafka, interpreted as a + hint; the larger of this and the partition count of the target topic is used instead.

Default: 1.

requiredGroups
A comma-separated list of groups to which the producer must ensure message delivery even if they start after it has been created (e.g., by pre-creating durable queues in RabbitMQ).
headerMode

When set to raw, disables header embedding on output. +Effective only for messaging middleware that does not support message headers natively and requires header embedding. +Useful when producing data for non-Spring Cloud Stream applications.

Default: embeddedHeaders.

useNativeEncoding

When set to true, the outbound message is serialized directly by client library, which must be configured correspondingly (e.g. setting an appropriate Kafka producer value serializer). +When this configuration is being used, the outbound message marshalling is not based on the contentType of the binding. +When native encoding is used, it is the responsibility of the consumer to use appropriate decoder (ex: Kafka consumer value de-serializer) to deserialize the inbound message. +Also, when native encoding/decoding is used the headerMode property is ignored and headers will not be embedded into the message.

Default: false.

errorChannelEnabled

When set to true, if the binder supports async send results; send failures will be sent to an error channel for the destination. +See the section called “Message Channel Binders and Error Channels” for more information.

Default: false.

28.3 Using dynamically bound destinations

Besides the channels defined via @EnableBinding, Spring Cloud Stream allows applications to send messages to dynamically bound destinations. +This is useful, for example, when the target destination needs to be determined at runtime. +Applications can do so by using the BinderAwareChannelResolver bean, registered automatically by the @EnableBinding annotation.

The property 'spring.cloud.stream.dynamicDestinations' can be used for restricting the dynamic destination names to a set known beforehand (whitelisting). +If the property is not set, any destination can be bound dynamicaly.

The BinderAwareChannelResolver can be used directly as in the following example, in which a REST controller uses a path variable to decide the target channel.

@EnableBinding
+@Controller
+public class SourceWithDynamicDestination {
+
+	@Autowired
+	private BinderAwareChannelResolver resolver;
+
+	@RequestMapping(path = "/{target}", method = POST, consumes = "*/*")
+	@ResponseStatus(HttpStatus.ACCEPTED)
+	public void handleRequest(@RequestBody String body, @PathVariable("target") target,
+	       @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) {
+		sendMessage(body, target, contentType);
+	}
+
+	private void sendMessage(String body, String target, Object contentType) {
+		resolver.resolveDestination(target).send(MessageBuilder.createMessage(body,
+				new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType))));
+	}
+}

After starting the application on the default port 8080, when sending the following data:

curl -H "Content-Type: application/json" -X POST -d "customer-1" http://localhost:8080/customers
+
+curl -H "Content-Type: application/json" -X POST -d "order-1" http://localhost:8080/orders

The destinations 'customers' and 'orders' are created in the broker (for example: exchange in case of Rabbit or topic in case of Kafka) with the names 'customers' and 'orders', and the data is published to the appropriate destinations.

The BinderAwareChannelResolver is a general purpose Spring Integration DestinationResolver and can be injected in other components. +For example, in a router using a SpEL expression based on the target field of an incoming JSON message.

@EnableBinding
+@Controller
+public class SourceWithDynamicDestination {
+
+	@Autowired
+	private BinderAwareChannelResolver resolver;
+
+
+	@RequestMapping(path = "/", method = POST, consumes = "application/json")
+	@ResponseStatus(HttpStatus.ACCEPTED)
+	public void handleRequest(@RequestBody String body, @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) {
+		sendMessage(body, contentType);
+	}
+
+	private void sendMessage(Object body, Object contentType) {
+		routerChannel().send(MessageBuilder.createMessage(body,
+				new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType))));
+	}
+
+	@Bean(name = "routerChannel")
+	public MessageChannel routerChannel() {
+		return new DirectChannel();
+	}
+
+	@Bean
+	@ServiceActivator(inputChannel = "routerChannel")
+	public ExpressionEvaluatingRouter router() {
+        ExpressionEvaluatingRouter router =
+            new ExpressionEvaluatingRouter(new SpelExpressionParser().parseExpression("payload.target"));
+		router.setDefaultOutputChannelName("default-output");
+		router.setChannelResolver(resolver);
+		return router;
+	}
+}
Prev Up Next
27. Binders Home 29. Content Type and Transformation
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81. Configuring Authentication Downstream of a Zuul Proxy
Prev Part XI. Spring Cloud Security Next

81. Configuring Authentication Downstream of a Zuul Proxy

You can control the authorization behaviour downstream of an +@EnableZuulProxy through the proxy.auth.* settings. Example:

application.yml.  +

proxy:
+  auth:
+    routes:
+      customers: oauth2
+      stores: passthru
+      recommendations: none

+

In this example the "customers" service gets an OAuth2 token relay, +the "stores" service gets a passthrough (the authorization header is +just passed downstream), and the "recommendations" service has its +authorization header removed. The default behaviour is to do a token +relay if there is a token available, and passthru otherwise.

See + +ProxyAuthenticationProperties for full details.

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80. More Detail Home Part XII. Spring Cloud for Cloud Foundry
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91. Contract DSL
Prev Part XIII. Spring Cloud Contract Next

91. Contract DSL

Spring Cloud Contract supports out of the box 2 types of DSL. One written in +Groovy and one written in YAML.

If you decide to write the contract in Groovy, do not be alarmed if you have not used Groovy +before. Knowledge of the language is not really needed, as the Contract DSL uses only a +tiny subset of it (only literals, method calls and closures). Also, the DSL is statically +typed, to make it programmer-readable without any knowledge of the DSL itself.

[Important]Important

Remember that, inside the Groovy contract file, you have to provide the fully +qualified name to the Contract class and make static imports, such as +org.springframework.cloud.spec.Contract.make { …​ }. You can also provide an import to +the Contract class: import org.springframework.cloud.spec.Contract and then call +Contract.make { …​ }.

[Tip]Tip

Spring Cloud Contract supports defining multiple contracts in a single file.

The following is a complete example of a Groovy contract definition:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'PUT'
+		url '/api/12'
+		headers {
+			header 'Content-Type': 'application/vnd.org.springframework.cloud.contract.verifier.twitter-places-analyzer.v1+json'
+		}
+		body '''\
+		[{
+			"created_at": "Sat Jul 26 09:38:57 +0000 2014",
+			"id": 492967299297845248,
+			"id_str": "492967299297845248",
+			"text": "Gonna see you at Warsaw",
+			"place":
+			{
+				"attributes":{},
+				"bounding_box":
+				{
+					"coordinates":
+						[[
+							[-77.119759,38.791645],
+							[-76.909393,38.791645],
+							[-76.909393,38.995548],
+							[-77.119759,38.995548]
+						]],
+					"type":"Polygon"
+				},
+				"country":"United States",
+				"country_code":"US",
+				"full_name":"Washington, DC",
+				"id":"01fbe706f872cb32",
+				"name":"Washington",
+				"place_type":"city",
+				"url": "https://api.twitter.com/1/geo/id/01fbe706f872cb32.json"
+			}
+		}]
+	'''
+	}
+	response {
+		status 200
+	}
+}

The following is a complete example of a YAML contract definition:

description: Some description
+name: some name
+priority: 8
+ignored: true
+request:
+  url: /foo
+  queryParameters:
+    a: b
+    b: c
+  method: PUT
+  headers:
+    foo: bar
+    fooReq: baz
+  body:
+    foo: bar
+  matchers:
+    body:
+      - path: $.foo
+        type: by_regex
+        value: bar
+    headers:
+      - key: foo
+        regex: bar
+response:
+  status: 200
+  headers:
+    foo2: bar
+    foo3: foo33
+    fooRes: baz
+  body:
+    foo2: bar
+    foo3: baz
+  matchers:
+    body:
+      - path: $.foo2
+        type: by_regex
+        value: bar
+      - path: $.foo3
+        type: by_command
+        value: executeMe($it)
+    headers:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        command: andMeToo($it)
[Tip]Tip

You can compile contracts to stubs mapping using standalone maven command: +mvn org.springframework.cloud:spring-cloud-contract-maven-plugin:convert

91.1 Limitations

[Warning]Warning

Spring Cloud Contract Verifier does not properly support XML. Please use JSON or +help us implement this feature.

[Warning]Warning

The support for verifying the size of JSON arrays is experimental. If you want +to turn it on, please set the value of the following system property to true: +spring.cloud.contract.verifier.assert.size. By default, this feature is set to false. +You can also provide the assertJsonSize property in the plugin configuration.

[Warning]Warning

Because JSON structure can have any form, it can be impossible to parse it +properly when using the Groovy DSL and the value(consumer(…​), producer(…​)) notation in GString. That +is why you should use the Groovy Map notation.

91.2 Common Top-Level elements

The following sections describe the most common top-level elements:

91.2.1 Description

You can add a description to your contract. The description is arbitrary text. The +following code shows an example:

Groovy DSL.  +

		org.springframework.cloud.contract.spec.Contract.make {
+			description('''
+given:
+	An input
+when:
+	Sth happens
+then:
+	Output
+''')
+		}

+

YAML.  +

description: Some description
+name: some name
+priority: 8
+ignored: true
+request:
+  url: /foo
+  queryParameters:
+    a: b
+    b: c
+  method: PUT
+  headers:
+    foo: bar
+    fooReq: baz
+  body:
+    foo: bar
+  matchers:
+    body:
+      - path: $.foo
+        type: by_regex
+        value: bar
+    headers:
+      - key: foo
+        regex: bar
+response:
+  status: 200
+  headers:
+    foo2: bar
+    foo3: foo33
+    fooRes: baz
+  body:
+    foo2: bar
+    foo3: baz
+  matchers:
+    body:
+      - path: $.foo2
+        type: by_regex
+        value: bar
+      - path: $.foo3
+        type: by_command
+        value: executeMe($it)
+    headers:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        command: andMeToo($it)

+

91.2.2 Name

You can provide a name for your contract. Assume that you provided the following name: +should register a user. If you do so, the name of the autogenerated test is +validate_should_register_a_user. Also, the name of the stub in a WireMock stub is +should_register_a_user.json.

[Important]Important

You must ensure that the name does not contain any characters that make the +generated test not compile. Also, remember that, if you provide the same name for +multiple contracts, your autogenerated tests fail to compile and your generated stubs +override each other.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	name("some_special_name")
+}

+

YAML.  +

name: some name

+

91.2.3 Ignoring Contracts

If you want to ignore a contract, you can either set a value of ignored contracts in the +plugin configuration or set the ignored property on the contract itself:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	ignored()
+}

+

YAML.  +

ignored: true

+

91.2.4 Passing Values from Files

Starting with version 1.2.0, you can pass values from files. Assume that you have the +following resources in our project.

└── src
+    └── test
+        └── resources
+            └── contracts
+                ├── readFromFile.groovy
+                ├── request.json
+                └── response.json

Further assume that your contract is as follows:

Groovy DSL.  +

import org.springframework.cloud.contract.spec.Contract
+
+Contract.make {
+	request {
+		method('PUT')
+		headers {
+			contentType(applicationJson())
+		}
+		body(file("request.json"))
+		url("/1")
+	}
+	response {
+		status 200
+		body(file("response.json"))
+		headers {
+			contentType(textPlain())
+		}
+	}
+}

+

YAML.  +

request:
+  method: GET
+  url: /foo
+  bodyFromFile: request.json
+response:
+  status: 200
+  bodyFromFile: response.json

+

Further assume that the JSON files is as follows:

request.json

{ "status" : "REQUEST" }

response.json

{ "status" : "RESPONSE" }

When test or stub generation takes place, the contents of the file is passed to the body +of a request or a response. The name of the file needs to be a file with location +relative to the folder in which the contract lays.

91.2.5 HTTP Top-Level Elements

The following methods can be called in the top-level closure of a contract definition. +request and response are mandatory. priority is optional.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	// Definition of HTTP request part of the contract
+	// (this can be a valid request or invalid depending
+	// on type of contract being specified).
+	request {
+		//...
+	}
+
+	// Definition of HTTP response part of the contract
+	// (a service implementing this contract should respond
+	// with following response after receiving request
+	// specified in "request" part above).
+	response {
+		//...
+	}
+
+	// Contract priority, which can be used for overriding
+	// contracts (1 is highest). Priority is optional.
+	priority 1
+}

+

YAML.  +

priority: 8
+request:
+...
+response:
+...

+

[Important]Important

If you want to make your contract have a higher value of priority +you need to pass a lower number to the priority tag / method. E.g. priority with +value 5 has higher priority than priority with value 10.

91.3 Request

The HTTP protocol requires only method and url to be specified in a request. The +same information is mandatory in request definition of the Contract.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		// HTTP request method (GET/POST/PUT/DELETE).
+		method 'GET'
+
+		// Path component of request URL is specified as follows.
+		urlPath('/users')
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

method: PUT
+url: /foo

+

It is possible to specify an absolute rather than relative url, but using urlPath is +the recommended way, as doing so makes the tests host-independent.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'GET'
+
+		// Specifying `url` and `urlPath` in one contract is illegal.
+		url('http://localhost:8888/users')
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+  method: PUT
+  urlPath: /foo

+

request may contain query parameters.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		urlPath('/users') {
+
+			// Each parameter is specified in form
+			// `'paramName' : paramValue` where parameter value
+			// may be a simple literal or one of matcher functions,
+			// all of which are used in this example.
+			queryParameters {
+
+				// If a simple literal is used as value
+				// default matcher function is used (equalTo)
+				parameter 'limit': 100
+
+				// `equalTo` function simply compares passed value
+				// using identity operator (==).
+				parameter 'filter': equalTo("email")
+
+				// `containing` function matches strings
+				// that contains passed substring.
+				parameter 'gender': value(consumer(containing("[mf]")), producer('mf'))
+
+				// `matching` function tests parameter
+				// against passed regular expression.
+				parameter 'offset': value(consumer(matching("[0-9]+")), producer(123))
+
+				// `notMatching` functions tests if parameter
+				// does not match passed regular expression.
+				parameter 'loginStartsWith': value(consumer(notMatching(".{0,2}")), producer(3))
+			}
+		}
+
+		//...
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+  queryParameters:
+    a: b
+    b: c
+  headers:
+    foo: bar
+    fooReq: baz
+  cookies:
+    foo: bar
+    fooReq: baz
+  body:
+    foo: bar
+  matchers:
+    body:
+      - path: $.foo
+        type: by_regex
+        value: bar
+    headers:
+      - key: foo
+        regex: bar
+response:
+  status: 200
+  fixedDelayMilliseconds: 1000
+  headers:
+    foo2: bar
+    foo3: foo33
+    fooRes: baz
+  body:
+    foo2: bar
+    foo3: baz
+  matchers:
+    body:
+      - path: $.foo2
+        type: by_regex
+        value: bar
+      - path: $.foo3
+        type: by_command
+        value: executeMe($it)
+    headers:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        command: andMeToo($it)
+    cookies:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        predefined:

+

request may contain additional request headers, as shown in the following example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		// Each header is added in form `'Header-Name' : 'Header-Value'`.
+		// there are also some helper methods
+		headers {
+			header 'key': 'value'
+			contentType(applicationJson())
+		}
+
+		//...
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+headers:
+  foo: bar
+  fooReq: baz

+

request may contain additional request cookies, as shown in the following example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		// Each Cookies is added in form `'Cookie-Key' : 'Cookie-Value'`.
+		// there are also some helper methods
+		cookies {
+			cookie 'key': 'value'
+			cookie('another_key', 'another_value')
+		}
+
+		//...
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+cookies:
+  foo: bar
+  fooReq: baz

+

request may contain a request body:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		// Currently only JSON format of request body is supported.
+		// Format will be determined from a header or body's content.
+		body '''{ "login" : "john", "name": "John The Contract" }'''
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+body:
+  foo: bar

+

request may contain multipart elements. To include multipart elements, use the +multipart method/section, as shown in the following examples

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract contractDsl = org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method "PUT"
+		url "/multipart"
+		headers {
+			contentType('multipart/form-data;boundary=AaB03x')
+		}
+		multipart(
+				// key (parameter name), value (parameter value) pair
+				formParameter: $(c(regex('".+"')), p('"formParameterValue"')),
+				someBooleanParameter: $(c(regex(anyBoolean())), p('true')),
+				// a named parameter (e.g. with `file` name) that represents file with
+				// `name` and `content`. You can also call `named("fileName", "fileContent")`
+				file: named(
+						// name of the file
+						name: $(c(regex(nonEmpty())), p('filename.csv')),
+						// content of the file
+						content: $(c(regex(nonEmpty())), p('file content')),
+						// content type for the part
+						contentType: $(c(regex(nonEmpty())), p('application/json')))
+		)
+	}
+	response {
+		status 200
+	}
+}

+

YAML.  +

request:
+  method: PUT
+  url: /multipart
+  headers:
+    Content-Type: multipart/form-data;boundary=AaB03x
+  multipart:
+    params:
+    # key (parameter name), value (parameter value) pair
+      formParameter: '"formParameterValue"'
+      someBooleanParameter: true
+    named:
+      - paramName: file
+        fileName: filename.csv
+        fileContent: file content
+  matchers:
+    multipart:
+      params:
+        - key: formParameter
+          regex: ".+"
+        - key: someBooleanParameter
+          predefined: any_boolean
+      named:
+        - paramName: file
+          fileName:
+            predefined: non_empty
+          fileContent:
+            predefined: non_empty
+response:
+  status: 200

+

In the preceding example, we define parameters in either of two ways:

Groovy DSL

  • Directly, by using the map notation, where the value can be a dynamic property (such as +formParameter: $(consumer(…​), producer(…​))).
  • By using the named(…​) method that lets you set a named parameter. A named parameter +can set a name and content. You can call it either via a method with two arguments, +such as named("fileName", "fileContent"), or via a map notation, such as +named(name: "fileName", content: "fileContent").

YAML

  • The multipart parameters are set via multipart.params section
  • The named parameters (the fileName and fileContent for a given parameter name) +can be set via the multipart.named section. That section contains +the paramName (name of the parameter), fileName (name of the file), +fileContent (content of the file) fields

  • The dynamic bits can be set via the matchers.multipart section

    • for parameters use the params section that can accept +regex or a predefined regular expression
    • for named params use the named section where first you +define the parameter name via paramName and then you can pass the +parametrization of either fileName or fileContent via +regex or a predefined regular expression

From this contract, the generated test is as follows:

// given:
+ MockMvcRequestSpecification request = given()
+   .header("Content-Type", "multipart/form-data;boundary=AaB03x")
+   .param("formParameter", "\"formParameterValue\"")
+   .param("someBooleanParameter", "true")
+   .multiPart("file", "filename.csv", "file content".getBytes());
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .put("/multipart");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);

The WireMock stub is as follows:

			'''
+{
+  "request" : {
+	"url" : "/multipart",
+	"method" : "PUT",
+	"headers" : {
+	  "Content-Type" : {
+		"matches" : "multipart/form-data;boundary=AaB03x.*"
+	  }
+	},
+	"bodyPatterns" : [ {
+		"matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"formParameter\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n\\".+\\"\\r\\n--\\\\1.*"
+  		}, {
+    			"matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"someBooleanParameter\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n(true|false)\\r\\n--\\\\1.*"
+  		}, {
+	  "matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"file\\"; filename=\\"[\\\\S\\\\s]+\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n[\\\\S\\\\s]+\\r\\n--\\\\1.*"
+	} ]
+  },
+  "response" : {
+	"status" : 200,
+	"transformers" : [ "response-template", "foo-transformer" ]
+  }
+}
+	'''

91.4 Response

The response must contain an HTTP status code and may contain other information. The +following code shows an example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+	}
+	response {
+		// Status code sent by the server
+		// in response to request specified above.
+		status 200
+	}
+}

+

YAML.  +

response:
+...
+status: 200

+

Besides status, the response may contain headers, cookies and a body, both of which are +specified the same way as in the request (see the previous paragraph).

91.5 Dynamic properties

The contract can contain some dynamic properties: timestamps, IDs, and so on. You do not +want to force the consumers to stub their clocks to always return the same value of time +so that it gets matched by the stub.

For Groovy DSL you can provide the dynamic parts in your contracts +in two ways: pass them directly in the body or set them in separate sections called +testMatchers and stubMatchers.

For YAML you can only use the matchers section.

91.5.1 Dynamic properties inside the body

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

You can set the properties inside the body either with the value method or, if you use +the Groovy map notation, with $(). The following example shows how to set dynamic +properties with the value method:

value(consumer(...), producer(...))
+value(c(...), p(...))
+value(stub(...), test(...))
+value(client(...), server(...))

The following example shows how to set dynamic properties with $():

$(consumer(...), producer(...))
+$(c(...), p(...))
+$(stub(...), test(...))
+$(client(...), server(...))

Both approaches work equally well. stub and client methods are aliases over the consumer +method. Subsequent sections take a closer look at what you can do with those values.

91.5.2 Regular expressions

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

You can use regular expressions to write your requests in Contract DSL. Doing so is +particularly useful when you want to indicate that a given response should be provided +for requests that follow a given pattern. Also, you can use regular expressions when you +need to use patterns and not exact values both for your test and your server side tests.

The following example shows how to use regular expressions to write a request:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method('GET')
+		url $(consumer(~/\/[0-9]{2}/), producer('/12'))
+	}
+	response {
+		status 200
+		body(
+				id: $(anyNumber()),
+				surname: $(
+						consumer('Kowalsky'),
+						producer(regex('[a-zA-Z]+'))
+				),
+				name: 'Jan',
+				created: $(consumer('2014-02-02 12:23:43'), producer(execute('currentDate(it)'))),
+				correlationId: value(consumer('5d1f9fef-e0dc-4f3d-a7e4-72d2220dd827'),
+						producer(regex('[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}'))
+				)
+		)
+		headers {
+			header 'Content-Type': 'text/plain'
+		}
+	}
+}

You can also provide only one side of the communication with a regular expression. If you +do so, then the contract engine automatically provides the generated string that matches +the provided regular expression. The following code shows an example:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'PUT'
+		url value(consumer(regex('/foo/[0-9]{5}')))
+		body([
+			requestElement: $(consumer(regex('[0-9]{5}')))
+		])
+		headers {
+			header('header', $(consumer(regex('application\\/vnd\\.fraud\\.v1\\+json;.*'))))
+		}
+	}
+	response {
+		status 200
+		body([
+			responseElement: $(producer(regex('[0-9]{7}')))
+		])
+		headers {
+			contentType("application/vnd.fraud.v1+json")
+		}
+	}
+}

In the preceding example, the opposite side of the communication has the respective data +generated for request and response.

Spring Cloud Contract comes with a series of predefined regular expressions that you can +use in your contracts, as shown in the following example:

protected static final Pattern TRUE_OR_FALSE = Pattern.compile(/(true|false)/)
+protected static final Pattern ONLY_ALPHA_UNICODE = Pattern.compile(/[\p{L}]*/)
+protected static final Pattern NUMBER = Pattern.compile('-?(\\d*\\.\\d+|\\d+)')
+protected static final Pattern IP_ADDRESS = Pattern.compile('([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])')
+protected static final Pattern HOSTNAME_PATTERN = Pattern.compile('((http[s]?|ftp):/)/?([^:/\\s]+)(:[0-9]{1,5})?')
+protected static final Pattern EMAIL = Pattern.compile('[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6}')
+protected static final Pattern URL = UrlHelper.URL
+protected static final Pattern UUID = Pattern.compile('[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}')
+protected static final Pattern ANY_DATE = Pattern.compile('(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])')
+protected static final Pattern ANY_DATE_TIME = Pattern.compile('([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])')
+protected static final Pattern ANY_TIME = Pattern.compile('(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])')
+protected static final Pattern NON_EMPTY = Pattern.compile(/[\S\s]+/)
+protected static final Pattern NON_BLANK = Pattern.compile(/^\s*\S[\S\s]*/)
+protected static final Pattern ISO8601_WITH_OFFSET = Pattern.compile(/([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.\d{3})?(Z|[+-][01]\d:[0-5]\d)/)
+
+protected static Pattern anyOf(String... values){
+	return Pattern.compile(values.collect({"^$it\$"}).join("|"))
+}
+
+String onlyAlphaUnicode() {
+	return ONLY_ALPHA_UNICODE.pattern()
+}
+
+String number() {
+	return NUMBER.pattern()
+}
+
+String anyBoolean() {
+	return TRUE_OR_FALSE.pattern()
+}
+
+String ipAddress() {
+	return IP_ADDRESS.pattern()
+}
+
+String hostname() {
+	return HOSTNAME_PATTERN.pattern()
+}
+
+String email() {
+	return EMAIL.pattern()
+}
+
+String url() {
+	return URL.pattern()
+}
+
+String uuid(){
+	return UUID.pattern()
+}
+
+String isoDate() {
+	return ANY_DATE.pattern()
+}
+
+String isoDateTime() {
+	return ANY_DATE_TIME.pattern()
+}
+
+String isoTime() {
+	return ANY_TIME.pattern()
+}
+
+String iso8601WithOffset() {
+	return ISO8601_WITH_OFFSET.pattern()
+}
+
+String nonEmpty() {
+	return NON_EMPTY.pattern()
+}
+
+String nonBlank() {
+	return NON_BLANK.pattern()
+}

In your contract, you can use it as shown in the following example:

Contract dslWithOptionalsInString = Contract.make {
+	priority 1
+	request {
+		method POST()
+		url '/users/password'
+		headers {
+			contentType(applicationJson())
+		}
+		body(
+				email: $(consumer(optional(regex(email()))), producer('abc@abc.com')),
+				callback_url: $(consumer(regex(hostname())), producer('https://partners.com'))
+		)
+	}
+	response {
+		status 404
+		headers {
+			contentType(applicationJson())
+		}
+		body(
+				code: value(consumer("123123"), producer(optional("123123"))),
+				message: "User not found by email = [${value(producer(regex(email())), consumer('not.existing@user.com'))}]"
+		)
+	}
+}

91.5.3 Passing Optional Parameters

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

It is possible to provide optional parameters in your contract. However, you can provide +optional parameters only for the following:

  • STUB side of the Request
  • TEST side of the Response

The following example shows how to provide optional parameters:

org.springframework.cloud.contract.spec.Contract.make {
+	priority 1
+	request {
+		method 'POST'
+		url '/users/password'
+		headers {
+			contentType(applicationJson())
+		}
+		body(
+				email: $(consumer(optional(regex(email()))), producer('abc@abc.com')),
+				callback_url: $(consumer(regex(hostname())), producer('https://partners.com'))
+		)
+	}
+	response {
+		status 404
+		headers {
+			header 'Content-Type': 'application/json'
+		}
+		body(
+				code: value(consumer("123123"), producer(optional("123123")))
+		)
+	}
+}

By wrapping a part of the body with the optional() method, you create a regular +expression that must be present 0 or more times.

If you use Spock for, the following test would be generated from the previous example:

"""
+ given:
+  def request = given()
+    .header("Content-Type", "application/json")
+    .body('''{"email":"abc@abc.com","callback_url":"https://partners.com"}''')
+
+ when:
+  def response = given().spec(request)
+    .post("/users/password")
+
+ then:
+  response.statusCode == 404
+  response.header('Content-Type')  == 'application/json'
+ and:
+  DocumentContext parsedJson = JsonPath.parse(response.body.asString())
+  assertThatJson(parsedJson).field("['code']").matches("(123123)?")
+"""

The following stub would also be generated:

'''
+{
+  "request" : {
+	"url" : "/users/password",
+	"method" : "POST",
+	"bodyPatterns" : [ {
+	  "matchesJsonPath" : "$[?(@.['email'] =~ /([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\\\.[a-zA-Z]{2,6})?/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.['callback_url'] =~ /((http[s]?|ftp):\\\\/)\\\\/?([^:\\\\/\\\\s]+)(:[0-9]{1,5})?/)]"
+	} ],
+	"headers" : {
+	  "Content-Type" : {
+		"equalTo" : "application/json"
+	  }
+	}
+  },
+  "response" : {
+	"status" : 404,
+	"body" : "{\\"code\\":\\"123123\\",\\"message\\":\\"User not found by email == [not.existing@user.com]\\"}",
+	"headers" : {
+	  "Content-Type" : "application/json"
+	}
+  },
+  "priority" : 1
+}
+'''

91.5.4 Executing Custom Methods on the Server Side

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

You can define a method call that executes on the server side during the test. Such a +method can be added to the class defined as "baseClassForTests" in the configuration. The +following code shows an example of the contract portion of the test case:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'PUT'
+		url $(consumer(regex('^/api/[0-9]{2}$')), producer('/api/12'))
+		headers {
+			header 'Content-Type': 'application/json'
+		}
+		body '''\
+				[{
+					"text": "Gonna see you at Warsaw"
+				}]
+			'''
+	}
+	response {
+		body (
+				path: $(consumer('/api/12'), producer(regex('^/api/[0-9]{2}$'))),
+				correlationId: $(consumer('1223456'), producer(execute('isProperCorrelationId($it)')))
+		)
+		status 200
+	}
+}

The following code shows the base class portion of the test case:

abstract class BaseMockMvcSpec extends Specification {
+
+	def setup() {
+		RestAssuredMockMvc.standaloneSetup(new PairIdController())
+	}
+
+	void isProperCorrelationId(Integer correlationId) {
+		assert correlationId == 123456
+	}
+
+	void isEmpty(String value) {
+		assert value == null
+	}
+
+}
[Important]Important

You cannot use both a String and execute to perform concatenation. For +example, calling header('Authorization', 'Bearer ' + execute('authToken()')) leads to +improper results. Instead, call header('Authorization', execute('authToken()')) and +ensure that the authToken() method returns everything you need.

The type of the object read from the JSON can be one of the following, depending on the +JSON path:

  • String: If you point to a String value in the JSON.
  • JSONArray: If you point to a List in the JSON.
  • Map: If you point to a Map in the JSON.
  • Number: If you point to Integer, Double etc. in the JSON.
  • Boolean: If you point to a Boolean in the JSON.

In the request part of the contract, you can specify that the body should be taken from +a method.

[Important]Important

You must provide both the consumer and the producer side. The execute part +is applied for the whole body - not for parts of it.

The following example shows how to read an object from JSON:

Contract contractDsl = Contract.make {
+	request {
+		method 'GET'
+		url '/something'
+		body(
+				$(c("foo"), p(execute("hashCode()")))
+		)
+	}
+	response {
+		status 200
+	}
+}

The preceding example results in calling the hashCode() method in the request body. +It should resemble the following code:

// given:
+ MockMvcRequestSpecification request = given()
+   .body(hashCode());
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .get("/something");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);

91.5.5 Referencing the Request from the Response

The best situation is to provide fixed values, but sometimes you need to reference a +request in your response.

If you’re writing contracts using Groovy DSL, you can use the fromRequest() method, which lets +you reference a bunch of elements from the HTTP request. You can use the following +options:

  • fromRequest().url(): Returns the request URL and query parameters.
  • fromRequest().query(String key): Returns the first query parameter with a given name.
  • fromRequest().query(String key, int index): Returns the nth query parameter with a +given name.
  • fromRequest().path(): Returns the full path.
  • fromRequest().path(int index): Returns the nth path element.
  • fromRequest().header(String key): Returns the first header with a given name.
  • fromRequest().header(String key, int index): Returns the nth header with a given name.
  • fromRequest().body(): Returns the full request body.
  • fromRequest().body(String jsonPath): Returns the element from the request that +matches the JSON Path.

If you’re using the YAML contract definition you have to use the +Handlebars {{{ }}} notation with custom, Spring Cloud Contract + functions to achieve this.

  • {{{ request.url }}}: Returns the request URL and query parameters.
  • {{{ request.query.key.[index] }}}: Returns the nth query parameter with a given name. +E.g. for key foo, first entry {{{ request.query.foo.[0] }}}
  • {{{ request.path }}}: Returns the full path.
  • {{{ request.path.[index] }}}: Returns the nth path element. E.g. +for first entry `{{{ request.path.[0] }}}
  • {{{ request.headers.key }}}: Returns the first header with a given name.
  • {{{ request.headers.key.[index] }}}: Returns the nth header with a given name.
  • {{{ request.body }}}: Returns the full request body.
  • {{{ jsonpath this 'your.json.path' }}}: Returns the element from the request that +matches the JSON Path. E.g. for json path $.foo - {{{ jsonpath this '$.foo' }}}

Consider the following contract:

Groovy DSL.  +

Contract contractDsl = Contract.make {
+	request {
+		method 'GET'
+		url('/api/v1/xxxx') {
+			queryParameters {
+				parameter("foo", "bar")
+				parameter("foo", "bar2")
+			}
+		}
+		headers {
+			header(authorization(), "secret")
+			header(authorization(), "secret2")
+		}
+		body(foo: "bar", baz: 5)
+	}
+	response {
+		status 200
+		headers {
+			header(authorization(), "foo ${fromRequest().header(authorization())} bar")
+		}
+		body(
+				url: fromRequest().url(),
+				path: fromRequest().path(),
+				pathIndex: fromRequest().path(1),
+				param: fromRequest().query("foo"),
+				paramIndex: fromRequest().query("foo", 1),
+				authorization: fromRequest().header("Authorization"),
+				authorization2: fromRequest().header("Authorization", 1),
+				fullBody: fromRequest().body(),
+				responseFoo: fromRequest().body('$.foo'),
+				responseBaz: fromRequest().body('$.baz'),
+				responseBaz2: "Bla bla ${fromRequest().body('$.foo')} bla bla"
+		)
+	}
+}

+

YAML.  +

request:
+  method: GET
+  url: /api/v1/xxxx
+  queryParameters:
+    foo:
+      - bar
+      - bar2
+  headers:
+    Authorization:
+      - secret
+      - secret2
+  body:
+    foo: bar
+    baz: 5
+response:
+  status: 200
+  headers:
+    Authorization: "foo {{{ request.headers.Authorization.0 }}} bar"
+  body:
+    url: "{{{ request.url }}}"
+    path: "{{{ request.path }}}"
+    pathIndex: "{{{ request.path.1 }}}"
+    param: "{{{ request.query.foo }}}"
+    paramIndex: "{{{ request.query.foo.1 }}}"
+    authorization: "{{{ request.headers.Authorization.0 }}}"
+    authorization2: "{{{ request.headers.Authorization.1 }}"
+    fullBody: "{{{ request.body }}}"
+    responseFoo: "{{{ jsonpath this '$.foo' }}}"
+    responseBaz: "{{{ jsonpath this '$.baz' }}}"
+    responseBaz2: "Bla bla {{{ jsonpath this '$.foo' }}} bla bla"

+

Running a JUnit test generation leads to a test that resembles the following example:

// given:
+ MockMvcRequestSpecification request = given()
+   .header("Authorization", "secret")
+   .header("Authorization", "secret2")
+   .body("{\"foo\":\"bar\",\"baz\":5}");
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .queryParam("foo","bar")
+   .queryParam("foo","bar2")
+   .get("/api/v1/xxxx");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);
+ assertThat(response.header("Authorization")).isEqualTo("foo secret bar");
+// and:
+ DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+ assertThatJson(parsedJson).field("['fullBody']").isEqualTo("{\"foo\":\"bar\",\"baz\":5}");
+ assertThatJson(parsedJson).field("['authorization']").isEqualTo("secret");
+ assertThatJson(parsedJson).field("['authorization2']").isEqualTo("secret2");
+ assertThatJson(parsedJson).field("['path']").isEqualTo("/api/v1/xxxx");
+ assertThatJson(parsedJson).field("['param']").isEqualTo("bar");
+ assertThatJson(parsedJson).field("['paramIndex']").isEqualTo("bar2");
+ assertThatJson(parsedJson).field("['pathIndex']").isEqualTo("v1");
+ assertThatJson(parsedJson).field("['responseBaz']").isEqualTo(5);
+ assertThatJson(parsedJson).field("['responseFoo']").isEqualTo("bar");
+ assertThatJson(parsedJson).field("['url']").isEqualTo("/api/v1/xxxx?foo=bar&foo=bar2");
+ assertThatJson(parsedJson).field("['responseBaz2']").isEqualTo("Bla bla bar bla bla");

As you can see, elements from the request have been properly referenced in the response.

The generated WireMock stub should resemble the following example:

{
+  "request" : {
+    "urlPath" : "/api/v1/xxxx",
+    "method" : "POST",
+    "headers" : {
+      "Authorization" : {
+        "equalTo" : "secret2"
+      }
+    },
+    "queryParameters" : {
+      "foo" : {
+        "equalTo" : "bar2"
+      }
+    },
+    "bodyPatterns" : [ {
+      "matchesJsonPath" : "$[?(@.['baz'] == 5)]"
+    }, {
+      "matchesJsonPath" : "$[?(@.['foo'] == 'bar')]"
+    } ]
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "{\"authorization\":\"{{{request.headers.Authorization.[0]}}}\",\"path\":\"{{{request.path}}}\",\"responseBaz\":{{{jsonpath this '$.baz'}}} ,\"param\":\"{{{request.query.foo.[0]}}}\",\"pathIndex\":\"{{{request.path.[1]}}}\",\"responseBaz2\":\"Bla bla {{{jsonpath this '$.foo'}}} bla bla\",\"responseFoo\":\"{{{jsonpath this '$.foo'}}}\",\"authorization2\":\"{{{request.headers.Authorization.[1]}}}\",\"fullBody\":\"{{{escapejsonbody}}}\",\"url\":\"{{{request.url}}}\",\"paramIndex\":\"{{{request.query.foo.[1]}}}\"}",
+    "headers" : {
+      "Authorization" : "{{{request.headers.Authorization.[0]}}};foo"
+    },
+    "transformers" : [ "response-template" ]
+  }
+}

Sending a request such as the one presented in the request part of the contract results +in sending the following response body:

{
+  "url" : "/api/v1/xxxx?foo=bar&foo=bar2",
+  "path" : "/api/v1/xxxx",
+  "pathIndex" : "v1",
+  "param" : "bar",
+  "paramIndex" : "bar2",
+  "authorization" : "secret",
+  "authorization2" : "secret2",
+  "fullBody" : "{\"foo\":\"bar\",\"baz\":5}",
+  "responseFoo" : "bar",
+  "responseBaz" : 5,
+  "responseBaz2" : "Bla bla bar bla bla"
+}
[Important]Important

This feature works only with WireMock having a version greater than or equal +to 2.5.1. The Spring Cloud Contract Verifier uses WireMock’s +response-template response transformer. It uses Handlebars to convert the Mustache {{{ }}} templates into +proper values. Additionally, it registers two helper functions:

  • escapejsonbody: Escapes the request body in a format that can be embedded in a JSON.
  • jsonpath: For a given parameter, find an object in the request body.

91.5.6 Registering Your Own WireMock Extension

WireMock lets you register custom extensions. By default, Spring Cloud Contract registers +the transformer, which lets you reference a request from a response. If you want to +provide your own extensions, you can register an implementation of the +org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions interface. +Since we use the spring.factories extension approach, you can create an entry in +META-INF/spring.factories file similar to the following:

org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions=\
+org.springframework.cloud.contract.stubrunner.provider.wiremock.TestWireMockExtensions

The following is an example of a custom extension:

TestWireMockExtensions.groovy.  +

package org.springframework.cloud.contract.verifier.dsl.wiremock
+
+import com.github.tomakehurst.wiremock.extension.Extension
+
+/**
+ * Extension that registers the default transformer and the custom one
+ */
+class TestWireMockExtensions implements WireMockExtensions {
+	@Override
+	List<Extension> extensions() {
+		return [
+				new DefaultResponseTransformer(),
+				new CustomExtension()
+		]
+	}
+}
+
+class CustomExtension implements Extension {
+
+	@Override
+	String getName() {
+		return "foo-transformer"
+	}
+}

+

[Important]Important

Remember to override the applyGlobally() method and set it to false if you +want the transformation to be applied only for a mapping that explicitly requires it.

91.5.7 Dynamic Properties in the Matchers Sections

If you work with Pact, the following discussion may seem familiar. +Quite a few users are used to having a separation between the body and setting the +dynamic parts of a contract.

You can use two separate sections:

  • stubMatchers, which lets you define the dynamic values that should end up in a stub. +You can set it in the request or inputMessage part of your contract.
  • testMatchers, which is present in the response or outputMessage side of the +contract.

Currently, Spring Cloud Contract Verifier supports only JSON Path-based matchers with the +following matching possibilities:

Groovy DSL

  • For stubMatchers:

    • byEquality(): The value taken from the request via the provided JSON Path must be +equal to the value provided in the contract.
    • byRegex(…​): The value taken from the request via the provided JSON Path must +match the regex.
    • byDate(): The value taken from the request via the provided JSON Path must +match the regex for an ISO Date value.
    • byTimestamp(): The value taken from the request via the provided JSON Path must +match the regex for an ISO DateTime value.
    • byTime(): The value taken from the request via the provided JSON Path must +match the regex for an ISO Time value.

  • For testMatchers:

    • byEquality(): The value taken from the response via the provided JSON Path must be +equal to the provided value in the contract.
    • byRegex(…​): The value taken from the response via the provided JSON Path must +match the regex.
    • byDate(): The value taken from the response via the provided JSON Path must match +the regex for an ISO Date value.
    • byTimestamp(): The value taken from the response via the provided JSON Path must +match the regex for an ISO DateTime value.
    • byTime(): The value taken from the response via the provided JSON Path must match +the regex for an ISO Time value.
    • byType(): The value taken from the response via the provided JSON Path needs to be +of the same type as the type defined in the body of the response in the contract. +byType can take a closure, in which you can set minOccurrence and maxOccurrence. +That way, you can assert the size of the flattened collection. To check the size of an +unflattened collection, use a custom method with the byCommand(…​) testMatcher.

    • byCommand(…​): The value taken from the response via the provided JSON Path is +passed as an input to the custom method that you provide. For example, +byCommand('foo($it)') results in calling a foo method to which the value matching the +JSON Path gets passed. The type of the object read from the JSON can be one of the +following, depending on the JSON path:

      • String: If you point to a String value.
      • JSONArray: If you point to a List.
      • Map: If you point to a Map.
      • Number: If you point to Integer, Double, or other kind of number.
      • Boolean: If you point to a Boolean.

YAML. Please read the Groovy section for detailed explanation of +what the types mean

For YAML the structure of a matcher looks like this

- path: $.foo
+  type: by_regex
+  value: bar

Or if you want to use one of the predefined regular expressions +[only_alpha_unicode, number, any_boolean, ip_address, hostname, +email, url, uuid, iso_date, iso_date_time, iso_time, iso_8601_with_offset, non_empty, non_blank]:

- path: $.foo
+  type: by_regex
+  predefined: only_alpha_unicode

Below you can find the allowed list of `type`s.

  • For stubMatchers:

    • by_equality
    • by_regex
    • by_date
    • by_timestamp
    • by_time

  • For testMatchers:

    • by_equality
    • by_regex
    • by_date
    • by_timestamp
    • by_time

    • by_type

      • there are 2 additional fields accepted: minOccurrence and maxOccurrence.
    • by_command

Consider the following example:

Groovy DSL.  +

Contract contractDsl = Contract.make {
+	request {
+		method 'GET'
+		urlPath '/get'
+		body([
+				duck: 123,
+				alpha: "abc",
+				number: 123,
+				aBoolean: true,
+				date: "2017-01-01",
+				dateTime: "2017-01-01T01:23:45",
+				time: "01:02:34",
+				valueWithoutAMatcher: "foo",
+				valueWithTypeMatch: "string",
+				key: [
+						'complex.key' : 'foo'
+				]
+		])
+		stubMatchers {
+			jsonPath('$.duck', byRegex("[0-9]{3}"))
+			jsonPath('$.duck', byEquality())
+			jsonPath('$.alpha', byRegex(onlyAlphaUnicode()))
+			jsonPath('$.alpha', byEquality())
+			jsonPath('$.number', byRegex(number()))
+			jsonPath('$.aBoolean', byRegex(anyBoolean()))
+			jsonPath('$.date', byDate())
+			jsonPath('$.dateTime', byTimestamp())
+			jsonPath('$.time', byTime())
+			jsonPath("\$.['key'].['complex.key']", byEquality())
+		}
+		headers {
+			contentType(applicationJson())
+		}
+	}
+	response {
+		status 200
+		body([
+				duck: 123,
+				alpha: "abc",
+				number: 123,
+				aBoolean: true,
+				date: "2017-01-01",
+				dateTime: "2017-01-01T01:23:45",
+				time: "01:02:34",
+				valueWithoutAMatcher: "foo",
+				valueWithTypeMatch: "string",
+				valueWithMin: [
+					1,2,3
+				],
+				valueWithMax: [
+					1,2,3
+				],
+				valueWithMinMax: [
+					1,2,3
+				],
+				valueWithMinEmpty: [],
+				valueWithMaxEmpty: [],
+				key: [
+				        'complex.key' : 'foo'
+				]
+		])
+		testMatchers {
+			// asserts the jsonpath value against manual regex
+			jsonPath('$.duck', byRegex("[0-9]{3}"))
+			// asserts the jsonpath value against the provided value
+			jsonPath('$.duck', byEquality())
+			// asserts the jsonpath value against some default regex
+			jsonPath('$.alpha', byRegex(onlyAlphaUnicode()))
+			jsonPath('$.alpha', byEquality())
+			jsonPath('$.number', byRegex(number()))
+			jsonPath('$.aBoolean', byRegex(anyBoolean()))
+			// asserts vs inbuilt time related regex
+			jsonPath('$.date', byDate())
+			jsonPath('$.dateTime', byTimestamp())
+			jsonPath('$.time', byTime())
+			// asserts that the resulting type is the same as in response body
+			jsonPath('$.valueWithTypeMatch', byType())
+			jsonPath('$.valueWithMin', byType {
+				// results in verification of size of array (min 1)
+				minOccurrence(1)
+			})
+			jsonPath('$.valueWithMax', byType {
+				// results in verification of size of array (max 3)
+				maxOccurrence(3)
+			})
+			jsonPath('$.valueWithMinMax', byType {
+				// results in verification of size of array (min 1 & max 3)
+				minOccurrence(1)
+				maxOccurrence(3)
+			})
+			jsonPath('$.valueWithMinEmpty', byType {
+				// results in verification of size of array (min 0)
+				minOccurrence(0)
+			})
+			jsonPath('$.valueWithMaxEmpty', byType {
+				// results in verification of size of array (max 0)
+				maxOccurrence(0)
+			})
+			// will execute a method `assertThatValueIsANumber`
+			jsonPath('$.duck', byCommand('assertThatValueIsANumber($it)'))
+			jsonPath("\$.['key'].['complex.key']", byEquality())
+		}
+		headers {
+			contentType(applicationJson())
+		}
+	}
+}

+

YAML.  +

request:
+  method: GET
+  urlPath: /get
+  body:
+    duck: 123
+    alpha: "abc"
+    number: 123
+    aBoolean: true
+    date: "2017-01-01"
+    dateTime: "2017-01-01T01:23:45"
+    time: "01:02:34"
+    valueWithoutAMatcher: "foo"
+    valueWithTypeMatch: "string"
+    key:
+      "complex.key": 'foo'
+  matchers:
+    headers:
+      - key: Content-Type
+        regex: "application/json.*"
+    body:
+      - path: $.duck
+        type: by_regex
+        value: "[0-9]{3}"
+      - path: $.duck
+        type: by_equality
+      - path: $.alpha
+        type: by_regex
+        predefined: only_alpha_unicode
+      - path: $.alpha
+        type: by_equality
+      - path: $.number
+        type: by_regex
+        predefined: number
+      - path: $.aBoolean
+        type: by_regex
+        predefined: any_boolean
+      - path: $.date
+        type: by_date
+      - path: $.dateTime
+        type: by_timestamp
+      - path: $.time
+        type: by_time
+      - path: "$.['key'].['complex.key']"
+        type: by_equality
+  headers:
+    Content-Type: application/json
+response:
+  status: 200
+  body:
+    duck: 123
+    alpha: "abc"
+    number: 123
+    aBoolean: true
+    date: "2017-01-01"
+    dateTime: "2017-01-01T01:23:45"
+    time: "01:02:34"
+    valueWithoutAMatcher: "foo"
+    valueWithTypeMatch: "string"
+    valueWithMin:
+      - 1
+      - 2
+      - 3
+    valueWithMax:
+      - 1
+      - 2
+      - 3
+    valueWithMinMax:
+      - 1
+      - 2
+      - 3
+    valueWithMinEmpty: []
+    valueWithMaxEmpty: []
+    key:
+      'complex.key' : 'foo'
+  matchers:
+    headers:
+      - key: Content-Type
+        regex: "application/json.*"
+    body:
+      - path: $.duck
+        type: by_regex
+        value: "[0-9]{3}"
+      - path: $.duck
+        type: by_equality
+      - path: $.alpha
+        type: by_regex
+        predefined: only_alpha_unicode
+      - path: $.alpha
+        type: by_equality
+      - path: $.number
+        type: by_regex
+        predefined: number
+      - path: $.aBoolean
+        type: by_regex
+        predefined: any_boolean
+      - path: $.date
+        type: by_date
+      - path: $.dateTime
+        type: by_timestamp
+      - path: $.time
+        type: by_time
+      - path: $.valueWithTypeMatch
+        type: by_type
+      - path: $.valueWithMin
+        type: by_type
+        minOccurrence: 1
+      - path: $.valueWithMax
+        type: by_type
+        maxOccurrence: 3
+      - path: $.valueWithMinMax
+        type: by_type
+        minOccurrence: 1
+        maxOccurrence: 3
+      - path: $.valueWithMinEmpty
+        type: by_type
+        minOccurrence: 0
+      - path: $.valueWithMaxEmpty
+        type: by_type
+        maxOccurrence: 0
+      - path: $.duck
+        type: by_command
+        value: assertThatValueIsANumber($it)
+  headers:
+    Content-Type: application/json

+

In the preceding example, you can see the dynamic portions of the contract in the +matchers sections. For the request part, you can see that, for all fields but +valueWithoutAMatcher, the values of the regular expressions that the stub should +contain are explicitly set. For the valueWithoutAMatcher, the verification takes place +in the same way as without the use of matchers. In that case, the test performs an +equality check.

For the response side in the testMatchers section, we define the dynamic parts in a +similar manner. The only difference is that the byType matchers are also present. The +verifier engine checks four fields to verify whether the response from the test +has a value for which the JSON path matches the given field, is of the same type as the one +defined in the response body, and passes the following check (based on the method being called):

  • For $.valueWithTypeMatch, the engine checks whether the type is the same.
  • For $.valueWithMin, the engine check the type and asserts whether the size is greater +than or equal to the minimum occurrence.
  • For $.valueWithMax, the engine checks the type and asserts whether the size is +smaller than or equal to the maximum occurrence.
  • For $.valueWithMinMax, the engine checks the type and asserts whether the size is +between the min and maximum occurrence.

The resulting test would resemble the following example (note that an and section +separates the autogenerated assertions and the assertion from matchers):

// given:
+ MockMvcRequestSpecification request = given()
+   .header("Content-Type", "application/json")
+   .body("{\"duck\":123,\"alpha\":\"abc\",\"number\":123,\"aBoolean\":true,\"date\":\"2017-01-01\",\"dateTime\":\"2017-01-01T01:23:45\",\"time\":\"01:02:34\",\"valueWithoutAMatcher\":\"foo\",\"valueWithTypeMatch\":\"string\"}");
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .get("/get");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);
+ assertThat(response.header("Content-Type")).matches("application/json.*");
+// and:
+ DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+ assertThatJson(parsedJson).field("valueWithoutAMatcher").isEqualTo("foo");
+// and:
+ assertThat(parsedJson.read("$.duck", String.class)).matches("[0-9]{3}");
+ assertThat(parsedJson.read("$.duck", Integer.class)).isEqualTo(123);
+ assertThat(parsedJson.read("$.alpha", String.class)).matches("[\\p{L}]*");
+ assertThat(parsedJson.read("$.alpha", String.class)).isEqualTo("abc");
+ assertThat(parsedJson.read("$.number", String.class)).matches("-?\\d*(\\.\\d+)?");
+ assertThat(parsedJson.read("$.aBoolean", String.class)).matches("(true|false)");
+ assertThat(parsedJson.read("$.date", String.class)).matches("(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])");
+ assertThat(parsedJson.read("$.dateTime", String.class)).matches("([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])");
+ assertThat(parsedJson.read("$.time", String.class)).matches("(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])");
+ assertThat((Object) parsedJson.read("$.valueWithTypeMatch")).isInstanceOf(java.lang.String.class);
+ assertThat((Object) parsedJson.read("$.valueWithMin")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMin", java.util.Collection.class)).hasSizeGreaterThanOrEqualTo(1);
+ assertThat((Object) parsedJson.read("$.valueWithMax")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMax", java.util.Collection.class)).hasSizeLessThanOrEqualTo(3);
+ assertThat((Object) parsedJson.read("$.valueWithMinMax")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMinMax", java.util.Collection.class)).hasSizeBetween(1, 3);
+ assertThat((Object) parsedJson.read("$.valueWithMinEmpty")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMinEmpty", java.util.Collection.class)).hasSizeGreaterThanOrEqualTo(0);
+ assertThat((Object) parsedJson.read("$.valueWithMaxEmpty")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMaxEmpty", java.util.Collection.class)).hasSizeLessThanOrEqualTo(0);
+ assertThatValueIsANumber(parsedJson.read("$.duck"));
[Important]Important

Notice that, for the byCommand method, the example calls the +assertThatValueIsANumber. This method must be defined in the test base class or be +statically imported to your tests. Notice that the byCommand call was converted to +assertThatValueIsANumber(parsedJson.read("$.duck"));. That means that the engine took +the method name and passed the proper JSON path as a parameter to it.

The resulting WireMock stub is in the following example:

				'''
+{
+  "request" : {
+	"urlPath" : "/get",
+	"method" : "POST",
+	"headers" : {
+	  "Content-Type" : {
+		"matches" : "application/json.*"
+	  }
+	},
+	"bodyPatterns" : [ {
+	  "matchesJsonPath" : "$[?(@.['valueWithoutAMatcher'] == 'foo')]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.['valueWithTypeMatch'] == 'string')]"
+	}, {
+	  "matchesJsonPath" : "$.['list'].['some'].['nested'][?(@.['anothervalue'] == 4)]"
+	}, {
+	  "matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['anothervalue'] == 4)]"
+	}, {
+	  "matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['json'] == 'with value')]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.duck =~ /([0-9]{3})/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.duck == 123)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.alpha =~ /([\\\\p{L}]*)/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.alpha == 'abc')]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.number =~ /(-?(\\\\d*\\\\.\\\\d+|\\\\d+))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.aBoolean =~ /((true|false))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.date =~ /((\\\\d\\\\d\\\\d\\\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01]))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.dateTime =~ /(([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.time =~ /((2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]"
+	}, {
+	  "matchesJsonPath" : "$.list.some.nested[?(@.json =~ /(.*)/)]"
+	} ]
+  },
+  "response" : {
+	"status" : 200,
+	"body" : "{\\"date\\":\\"2017-01-01\\",\\"dateTime\\":\\"2017-01-01T01:23:45\\",\\"number\\":123,\\"aBoolean\\":true,\\"duck\\":123,\\"alpha\\":\\"abc\\",\\"valueWithMin\\":[1,2,3],\\"time\\":\\"01:02:34\\",\\"valueWithTypeMatch\\":\\"string\\",\\"valueWithMax\\":[1,2,3],\\"valueWithMinMax\\":[1,2,3],\\"valueWithoutAMatcher\\":\\"foo\\"}",
+	"headers" : {
+	  "Content-Type" : "application/json"
+	}
+  }
+}
+'''
[Important]Important

If you use a matcher, then the part of the request aned response that the +matcher addresses with the JSON Path gets removed from the assertion. In the case of +verifying a collection, you must create matchers for all the elements of the +collection.

Consider the following example:

Contract.make {
+    request {
+        method 'GET'
+        url("/foo")
+    }
+    response {
+        status 200
+        body(events: [[
+                                 operation          : 'EXPORT',
+                                 eventId            : '16f1ed75-0bcc-4f0d-a04d-3121798faf99',
+                                 status             : 'OK'
+                         ], [
+                                 operation          : 'INPUT_PROCESSING',
+                                 eventId            : '3bb4ac82-6652-462f-b6d1-75e424a0024a',
+                                 status             : 'OK'
+                         ]
+                ]
+        )
+        testMatchers {
+            jsonPath('$.events[0].operation', byRegex('.+'))
+            jsonPath('$.events[0].eventId', byRegex('^([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})$'))
+            jsonPath('$.events[0].status', byRegex('.+'))
+        }
+    }
+}

The preceding code leads to creating the following test (the code block shows only the assertion section):

and:
+	DocumentContext parsedJson = JsonPath.parse(response.body.asString())
+	assertThatJson(parsedJson).array("['events']").contains("['eventId']").isEqualTo("16f1ed75-0bcc-4f0d-a04d-3121798faf99")
+	assertThatJson(parsedJson).array("['events']").contains("['operation']").isEqualTo("EXPORT")
+	assertThatJson(parsedJson).array("['events']").contains("['operation']").isEqualTo("INPUT_PROCESSING")
+	assertThatJson(parsedJson).array("['events']").contains("['eventId']").isEqualTo("3bb4ac82-6652-462f-b6d1-75e424a0024a")
+	assertThatJson(parsedJson).array("['events']").contains("['status']").isEqualTo("OK")
+and:
+	assertThat(parsedJson.read("\$.events[0].operation", String.class)).matches(".+")
+	assertThat(parsedJson.read("\$.events[0].eventId", String.class)).matches("^([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})\$")
+	assertThat(parsedJson.read("\$.events[0].status", String.class)).matches(".+")

As you can see, the assertion is malformed. Only the first element of the array got +asserted. In order to fix this, you should apply the assertion to the whole $.events +collection and assert it with the byCommand(…​) method.

91.6 JAX-RS Support

The Spring Cloud Contract Verifier supports the JAX-RS 2 Client API. The base class needs +to define protected WebTarget webTarget and server initialization. The only option for +testing JAX-RS API is to start a web server. Also, a request with a body needs to have a +content type set. Otherwise, the default of application/octet-stream gets used.

In order to use JAX-RS mode, use the following settings:

testMode == 'JAXRSCLIENT'

The following example shows a generated test API:

'''
+ // when:
+  Response response = webTarget
+    .path("/users")
+    .queryParam("limit", "10")
+    .queryParam("offset", "20")
+    .queryParam("filter", "email")
+    .queryParam("sort", "name")
+    .queryParam("search", "55")
+    .queryParam("age", "99")
+    .queryParam("name", "Denis.Stepanov")
+    .queryParam("email", "bob@email.com")
+    .request()
+    .method("GET");
+
+  String responseAsString = response.readEntity(String.class);
+
+ // then:
+  assertThat(response.getStatus()).isEqualTo(200);
+ // and:
+  DocumentContext parsedJson = JsonPath.parse(responseAsString);
+  assertThatJson(parsedJson).field("['property1']").isEqualTo("a");
+'''

91.7 Async Support

If you’re using asynchronous communication on the server side (your controllers are +returning Callable, DeferredResult, and so on), then, inside your contract, you must +provide a sync() method in the response section. The following code shows an example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+    request {
+        method GET()
+        url '/get'
+    }
+    response {
+        status 200
+        body 'Passed'
+        async()
+    }
+}

+

YAML.  +

response:
+    async: true

+

You can also use the fixedDelayMilliseconds method / property to add delay to your stubs.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+    request {
+        method GET()
+        url '/get'
+    }
+    response {
+        status 200
+        body 'Passed'
+        fixedDelayMilliseconds 1000
+    }
+}

+

YAML.  +

response:
+    fixedDelayMilliseconds: 1000

+

91.8 Working with Context Paths

Spring Cloud Contract supports context paths.

[Important]Important

The only change needed to fully support context paths is the switch on the +PRODUCER side. Also, the autogenerated tests must use EXPLICIT mode. The consumer +side remains untouched. In order for the generated test to pass, you must use EXPLICIT +mode.

Maven.  +

<plugin>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+    <version>${spring-cloud-contract.version}</version>
+    <extensions>true</extensions>
+    <configuration>
+        <testMode>EXPLICIT</testMode>
+    </configuration>
+</plugin>

+

Gradle.  +

contracts {
+		testMode = 'EXPLICIT'
+}

+

That way, you generate a test that DOES NOT use MockMvc. It means that you generate +real requests and you need to setup your generated test’s base class to work on a real +socket.

Consider the following contract:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'GET'
+		url '/my-context-path/url'
+	}
+	response {
+		status 200
+	}
+}

The following example shows how to set up a base class and Rest Assured:

import io.restassured.RestAssured;
+import org.junit.Before;
+import org.springframework.boot.context.embedded.LocalServerPort;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest(classes = ContextPathTestingBaseClass.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+class ContextPathTestingBaseClass {
+
+	@LocalServerPort int port;
+
+	@Before
+	public void setup() {
+		RestAssured.baseURI = "http://localhost";
+		RestAssured.port = this.port;
+	}
+}

If you do it this way:

  • All of your requests in the autogenerated tests are sent to the real endpoint with your +context path included (for example, /my-context-path/url).
  • Your contracts reflect that you have a context path. Your generated stubs also have +that information (for example, in the stubs, you have to call /my-context-path/url).

91.9 Messaging Top-Level Elements

The DSL for messaging looks a little bit different than the one that focuses on HTTP. The +following sections explain the differences:

91.9.1 Output Triggered by a Method

The output message can be triggered by calling a method (such as a Scheduler when a was +started and a message was sent), as shown in the following example:

Groovy DSL.  +

def dsl = Contract.make {
+	// Human readable description
+	description 'Some description'
+	// Label by means of which the output message can be triggered
+	label 'some_label'
+	// input to the contract
+	input {
+		// the contract will be triggered by a method
+		triggeredBy('bookReturnedTriggered()')
+	}
+	// output message of the contract
+	outputMessage {
+		// destination to which the output message will be sent
+		sentTo('output')
+		// the body of the output message
+		body('''{ "bookName" : "foo" }''')
+		// the headers of the output message
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

+

YAML.  +

# Human readable description
+description: Some description
+# Label by means of which the output message can be triggered
+label: some_label
+input:
+  # the contract will be triggered by a method
+  triggeredBy: bookReturnedTriggered()
+# output message of the contract
+outputMessage:
+  # destination to which the output message will be sent
+  sentTo: output
+  # the body of the output message
+  body:
+    bookName: foo
+  # the headers of the output message
+  headers:
+    BOOK-NAME: foo

+

In the previous example case, the output message is sent to output if a method called +bookReturnedTriggered is executed. On the message publisher’s side, we generate a +test that calls that method to trigger the message. On the consumer side, you can use +the some_label to trigger the message.

91.9.2 Output Triggered by a Message

The output message can be triggered by receiving a message, as shown in the following +example:

Groovy DSL.  +

def dsl = Contract.make {
+	description 'Some Description'
+	label 'some_label'
+	// input is a message
+	input {
+		// the message was received from this destination
+		messageFrom('input')
+		// has the following body
+		messageBody([
+		        bookName: 'foo'
+		])
+		// and the following headers
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('output')
+		body([
+		        bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

+

YAML.  +

# Human readable description
+description: Some description
+# Label by means of which the output message can be triggered
+label: some_label
+# input is a message
+input:
+  messageFrom: input
+  # has the following body
+  messageBody:
+    bookName: 'foo'
+  # and the following headers
+  messageHeaders:
+    sample: 'header'
+# output message of the contract
+outputMessage:
+  # destination to which the output message will be sent
+  sentTo: output
+  # the body of the output message
+  body:
+    bookName: foo
+  # the headers of the output message
+  headers:
+    BOOK-NAME: foo

+

In the preceding example, the output message is sent to output if a proper message is +received on the input destination. On the message publisher’s side, the engine +generates a test that sends the input message to the defined destination. On the +consumer side, you can either send a message to the input destination or use a label +(some_label in the example) to trigger the message.

91.9.3 Consumer/Producer

[Important]Important

This section is valid only for Groovy DSL.

In HTTP, you have a notion of client/stub and `server/test notation. You can also +use those paradigms in messaging. In addition, Spring Cloud Contract Verifier also +provides the consumer and producer methods, as presented in the following example +(note that you can use either $ or value methods to provide consumer and producer +parts):

Contract.make {
+	label 'some_label'
+	input {
+		messageFrom value(consumer('jms:output'), producer('jms:input'))
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo $(consumer('jms:input'), producer('jms:output'))
+		body([
+				bookName: 'foo'
+		])
+	}
+}

91.9.4 Common

In the input or outputMessage section you can call assertThat with the name +of a method (e.g. assertThatMessageIsOnTheQueue()) that you have defined in the +base class or in a static import. Spring Cloud Contract will execute that method +in the generated test.

91.10 Multiple Contracts in One File

You can define multiple contracts in one file. Such a contract might resemble the +following example:

Groovy DSL.  +

import org.springframework.cloud.contract.spec.Contract
+
+[
+        Contract.make {
+            name("should post a user")
+            request {
+                method 'POST'
+                url('/users/1')
+            }
+            response {
+                status 200
+            }
+        },
+        Contract.make {
+            request {
+                method 'POST'
+                url('/users/2')
+            }
+            response {
+                status 200
+            }
+        }
+]

+

YAML.  +

---
+name: should post a user
+request:
+  method: POST
+  url: /users/1
+response:
+  status: 200
+
+---
+request:
+  method: POST
+  url: /users/2
+response:
+  status: 200

+

In the preceding example, one contract has the name field and the other does not. This +leads to generation of two tests that look more or less like this:

package org.springframework.cloud.contract.verifier.tests.com.hello;
+
+import com.example.TestBase;
+import com.jayway.jsonpath.DocumentContext;
+import com.jayway.jsonpath.JsonPath;
+import com.jayway.restassured.module.mockmvc.specification.MockMvcRequestSpecification;
+import com.jayway.restassured.response.ResponseOptions;
+import org.junit.Test;
+
+import static com.jayway.restassured.module.mockmvc.RestAssuredMockMvc.*;
+import static com.toomuchcoding.jsonassert.JsonAssertion.assertThatJson;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class V1Test extends TestBase {
+
+	@Test
+	public void validate_should_post_a_user() throws Exception {
+		// given:
+			MockMvcRequestSpecification request = given();
+
+		// when:
+			ResponseOptions response = given().spec(request)
+					.post("/users/1");
+
+		// then:
+			assertThat(response.statusCode()).isEqualTo(200);
+	}
+
+	@Test
+	public void validate_withList_1() throws Exception {
+		// given:
+			MockMvcRequestSpecification request = given();
+
+		// when:
+			ResponseOptions response = given().spec(request)
+					.post("/users/2");
+
+		// then:
+			assertThat(response.statusCode()).isEqualTo(200);
+	}
+
+}

Notice that, for the contract that has the name field, the generated test method is named +validate_should_post_a_user. For the one that does not have the name, it is called +validate_withList_1. It corresponds to the name of the file WithList.groovy and the +index of the contract in the list.

The generated stubs is shown in the following example:

should post a user.json
+1_WithList.json

As you can see, the first file got the name parameter from the contract. The second +got the name of the contract file (WithList.groovy) prefixed with the index (in this +case, the contract had an index of 1 in the list of contracts in the file).

[Tip]Tip

As you can see, it iss much better if you name your contracts because doing so makes +your tests far more meaningful.

Prev Up Next
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92. Customization
Prev Part XIII. Spring Cloud Contract Next

92. Customization

[Important]Important

This section is valid only for Groovy DSL

You can customize the Spring Cloud Contract Verifier by extending the DSL, as shown in +the remainder of this section.

92.1 Extending the DSL

You can provide your own functions to the DSL. The key requirement for this feature is to +maintain the static compatibility. Later in this document, you can see examples of:

  • Creating a JAR with reusable classes.
  • Referencing of these classes in the DSLs.

You can find the full example +here.

92.1.1 Common JAR

The following examples show three classes that can be reused in the DSLs.

PatternUtils contains functions used by both the consumer and the producer.

package com.example;
+
+import java.util.regex.Pattern;
+
+/**
+ * If you want to use {@link Pattern} directly in your tests
+ * then you can create a class resembling this one. It can
+ * contain all the {@link Pattern} you want to use in the DSL.
+ *
+ * <pre>
+ * {@code
+ * request {
+ *     body(
+ *         [ age: $(c(PatternUtils.oldEnough()))]
+ *     )
+ * }
+ * </pre>
+ *
+ * Notice that we're using both {@code $()} for dynamic values
+ * and {@code c()} for the consumer side.
+ *
+ * @author Marcin Grzejszczak
+ */
+//tag::impl[]
+public class PatternUtils {
+
+	public static String tooYoung() {
+		//remove::start[]
+		return "[0-1][0-9]";
+		//remove::end[return]
+	}
+
+	public static Pattern oldEnough() {
+		//remove::start[]
+		return Pattern.compile("[2-9][0-9]");
+		//remove::end[return]
+	}
+
+	/**
+	 * Makes little sense but it's just an example ;)
+	 */
+	public static Pattern ok() {
+		//remove::start[]
+		return Pattern.compile("OK");
+		//remove::end[return]
+	}
+}
+//end::impl[]

ConsumerUtils contains functions used by the consumer.

package com.example;
+
+import org.springframework.cloud.contract.spec.internal.ClientDslProperty;
+
+/**
+ * DSL Properties passed to the DSL from the consumer's perspective.
+ * That means that on the input side {@code Request} for HTTP
+ * or {@code Input} for messaging you can have a regular expression.
+ * On the {@code Response} for HTTP or {@code Output} for messaging
+ * you have to have a concrete value.
+ *
+ * @author Marcin Grzejszczak
+ */
+//tag::impl[]
+public class ConsumerUtils {
+	/**
+	 * Consumer side property. By using the {@link ClientDslProperty}
+	 * you can omit most of boilerplate code from the perspective
+	 * of dynamic values. Example
+	 *
+	 * <pre>
+	 * {@code
+	 * request {
+	 *     body(
+	 *         [ age: $(ConsumerUtils.oldEnough())]
+	 *     )
+	 * }
+	 * </pre>
+	 *
+	 * That way it's in the implementation that we decide what value we will pass to the consumer
+	 * and which one to the producer.
+	 *
+	 * @author Marcin Grzejszczak
+	 */
+	public static ClientDslProperty oldEnough() {
+		//remove::start[]
+		// this example is not the best one and
+		// theoretically you could just pass the regex instead of `ServerDslProperty` but
+		// it's just to show some new tricks :)
+		return new ClientDslProperty(PatternUtils.oldEnough(), 40);
+		//remove::end[return]
+	}
+
+}
+//end::impl[]

ProducerUtils contains functions used by the producer.

package com.example;
+
+import org.springframework.cloud.contract.spec.internal.ServerDslProperty;
+
+/**
+ * DSL Properties passed to the DSL from the producer's perspective.
+ * That means that on the input side {@code Request} for HTTP
+ * or {@code Input} for messaging you have to have a concrete value.
+ * On the {@code Response} for HTTP or {@code Output} for messaging
+ * you can have a regular expression.
+ *
+ * @author Marcin Grzejszczak
+ */
+//tag::impl[]
+public class ProducerUtils {
+
+	/**
+	 * Producer side property. By using the {@link ProducerUtils}
+	 * you can omit most of boilerplate code from the perspective
+	 * of dynamic values. Example
+	 *
+	 * <pre>
+	 * {@code
+	 * response {
+	 *     body(
+	 *         [ status: $(ProducerUtils.ok())]
+	 *     )
+	 * }
+	 * </pre>
+	 *
+	 * That way it's in the implementation that we decide what value we will pass to the consumer
+	 * and which one to the producer.
+	 */
+	public static ServerDslProperty ok() {
+		// this example is not the best one and
+		// theoretically you could just pass the regex instead of `ServerDslProperty` but
+		// it's just to show some new tricks :)
+		return new ServerDslProperty( PatternUtils.ok(), "OK");
+	}
+}
+//end::impl[]

92.1.2 Adding the Dependency to the Project

In order for the plugins and IDE to be able to reference the common JAR classes, you need +to pass the dependency to your project.

92.1.3 Test the Dependency in the Project’s Dependencies

First, add the common jar dependency as a test dependency. Because your contracts files +are available on the test resources path, the common jar classes automatically become +visible in your Groovy files. The following examples show how to test the dependency:

Maven.  +

<dependency>
+	<groupId>com.example</groupId>
+	<artifactId>beer-common</artifactId>
+	<version>${project.version}</version>
+	<scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile("com.example:beer-common:0.0.1.BUILD-SNAPSHOT")

+

92.1.4 Test a Dependency in the Plugin’s Dependencies

Now, you must add the dependency for the plugin to reuse at runtime, as shown in the +following example:

Maven.  +

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example</packageWithBaseClasses>
+		<baseClassMappings>
+			<baseClassMapping>
+				<contractPackageRegex>.*intoxication.*</contractPackageRegex>
+				<baseClassFQN>com.example.intoxication.BeerIntoxicationBase</baseClassFQN>
+			</baseClassMapping>
+		</baseClassMappings>
+	</configuration>
+	<dependencies>
+		<dependency>
+			<groupId>com.example</groupId>
+			<artifactId>beer-common</artifactId>
+			<version>${project.version}</version>
+			<scope>compile</scope>
+		</dependency>
+	</dependencies>
+</plugin>

+

Gradle.  +

classpath "com.example:beer-common:0.0.1.BUILD-SNAPSHOT"

+

92.1.5 Referencing classes in DSLs

You can now reference your classes in your DSL, as shown in the following example:

package contracts.beer.rest
+
+import com.example.ConsumerUtils
+import com.example.ProducerUtils
+import org.springframework.cloud.contract.spec.Contract
+
+Contract.make {
+	description("""
+Represents a successful scenario of getting a beer
+
+```
+given:
+	client is old enough
+when:
+	he applies for a beer
+then:
+	we'll grant him the beer
+```
+
+""")
+	request {
+		method 'POST'
+		url '/check'
+		body(
+				age: $(ConsumerUtils.oldEnough())
+		)
+		headers {
+			contentType(applicationJson())
+		}
+	}
+	response {
+		status 200
+		body("""
+			{
+				"status": "${value(ProducerUtils.ok())}"
+			}
+			""")
+		headers {
+			contentType(applicationJson())
+		}
+	}
+}
Prev Up Next
91. Contract DSL Home 93. Using the Pluggable Architecture
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54. Customizations
Prev Part VII. Spring Cloud Sleuth Next

54. Customizations

Thanks to the SpanInjector and SpanExtractor you can customize the way spans +are created and propagated.

There are currently two built-in ways to pass tracing information between processes:

  • via Spring Integration
  • via HTTP

Span ids are extracted from Zipkin-compatible (B3) headers (either Message +or HTTP headers), to start or join an existing trace. Trace information is +injected into any outbound requests so the next hop can extract them.

The default way of coding tracing context is done via the b3 header that contains the +traceId-spanId-sampled notation (e.g. 0000000000000005-0000000000000004-1). +For backward compatibility, if the b3 header is not present, we also check if +X-B3 entries are present, and retrieve tracing context from there e.g. +(X-B3-TraceId: 0000000000000005, X-B3-SpanId: 0000000000000004, X-B3-Sampled: 1).

The key change in comparison to the previous versions of Sleuth is that Sleuth is implementing +the Open Tracing’s TextMap notion. In Sleuth it’s called SpanTextMap. Basically the idea +is that any means of communication (e.g. message, http request, etc.) can be abstracted via +a SpanTextMap. This abstraction defines how one can insert data into the carrier and +how to retrieve it from there. Thanks to this if you want to instrument a new HTTP library +that uses a FooRequest as a mean of sending HTTP requests then you have to create an +implementation of a SpanTextMap that delegates calls to FooRequest in terms of retrieval +and insertion of HTTP headers.

54.1 Spring Integration

For Spring Integration there are 2 interfaces responsible for creation of a Span from a Message. +These are:

  • MessagingSpanTextMapExtractor
  • MessagingSpanTextMapInjector

You can override them by providing your own implementation.

54.2 HTTP

For HTTP there are 2 interfaces responsible for creation of a Span from a Message. +These are:

  • HttpSpanExtractor
  • HttpSpanInjector

You can override them by providing your own implementation.

54.3 Example

Let’s assume that instead of the standard Zipkin compatible tracing HTTP header names +you have

  • for trace id - correlationId
  • for span id - mySpanId

This is a an example of a SpanExtractor

static class CustomHttpSpanExtractor implements HttpSpanExtractor {
+
+	@Override public Span joinTrace(SpanTextMap carrier) {
+		Map<String, String> map = TextMapUtil.asMap(carrier);
+		long traceId = Span.hexToId(map.get("correlationid"));
+		long spanId = Span.hexToId(map.get("myspanid"));
+		// extract all necessary headers
+		Span.SpanBuilder builder = Span.builder().traceId(traceId).spanId(spanId);
+		// build rest of the Span
+		return builder.build();
+	}
+}
+
+static class CustomHttpSpanInjector implements HttpSpanInjector {
+
+	@Override
+	public void inject(Span span, SpanTextMap carrier) {
+		carrier.put("correlationId", span.traceIdString());
+		carrier.put("mySpanId", Span.idToHex(span.getSpanId()));
+	}
+}

And you could register it like this:

@Bean
+HttpSpanInjector customHttpSpanInjector() {
+	return new CustomHttpSpanInjector();
+}
+
+@Bean
+HttpSpanExtractor customHttpSpanExtractor() {
+	return new CustomHttpSpanExtractor();
+}

Spring Cloud Sleuth does not add trace/span related headers to the Http Response for security reasons. If you need the headers then a custom SpanInjector +that injects the headers into the Http Response and a Servlet filter which makes use of this can be added the following way:

static class CustomHttpServletResponseSpanInjector extends ZipkinHttpSpanInjector {
+
+	@Override
+	public void inject(Span span, SpanTextMap carrier) {
+		super.inject(span, carrier);
+		carrier.put(Span.TRACE_ID_NAME, span.traceIdString());
+		carrier.put(Span.SPAN_ID_NAME, Span.idToHex(span.getSpanId()));
+	}
+}
+
+static class HttpResponseInjectingTraceFilter extends GenericFilterBean {
+
+	private final Tracer tracer;
+	private final HttpSpanInjector spanInjector;
+
+	public HttpResponseInjectingTraceFilter(Tracer tracer, HttpSpanInjector spanInjector) {
+		this.tracer = tracer;
+		this.spanInjector = spanInjector;
+	}
+
+	@Override
+	public void doFilter(ServletRequest request, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
+		HttpServletResponse response = (HttpServletResponse) servletResponse;
+		Span currentSpan = this.tracer.getCurrentSpan();
+		this.spanInjector.inject(currentSpan, new HttpServletResponseTextMap(response));
+		filterChain.doFilter(request, response);
+	}
+
+	 class HttpServletResponseTextMap implements SpanTextMap {
+
+		 private final HttpServletResponse delegate;
+
+		 HttpServletResponseTextMap(HttpServletResponse delegate) {
+			 this.delegate = delegate;
+		 }
+
+		 @Override
+		 public Iterator<Map.Entry<String, String>> iterator() {
+			 Map<String, String> map = new HashMap<>();
+			 for (String header : this.delegate.getHeaderNames()) {
+				map.put(header, this.delegate.getHeader(header));
+			 }
+			 return map.entrySet().iterator();
+		 }
+
+		 @Override
+		 public void put(String key, String value) {
+			this.delegate.addHeader(key, value);
+		 }
+	 }
+}

And you could register them like this:

@Bean HttpSpanInjector customHttpServletResponseSpanInjector() {
+	return new CustomHttpServletResponseSpanInjector();
+}
+
+@Bean
+HttpResponseInjectingTraceFilter responseInjectingTraceFilter(Tracer tracer) {
+	return new HttpResponseInjectingTraceFilter(tracer, customHttpServletResponseSpanInjector());
+}

54.4 TraceFilter

You can also modify the behaviour of the TraceFilter - the component that is responsible +for processing the input HTTP request and adding tags basing on the HTTP response. You can customize +the tags, or modify the response headers by registering your own instance of the TraceFilter bean.

In the following example we will register the TraceFilter bean and we will add the +ZIPKIN-TRACE-ID response header containing the current Span’s trace id. Also we will +add to the Span a tag with key custom and a value tag.

@Bean
+TraceFilter myTraceFilter(BeanFactory beanFactory, final Tracer tracer) {
+	return new TraceFilter(beanFactory) {
+		@Override protected void addResponseTags(HttpServletResponse response,
+				Throwable e) {
+			// execute the default behaviour
+			super.addResponseTags(response, e);
+			// for readability we're returning trace id in a hex form
+			response.addHeader("ZIPKIN-TRACE-ID",
+					Span.idToHex(tracer.getCurrentSpan().getTraceId()));
+			// we can also add some custom tags
+			tracer.addTag("custom", "tag");
+		}
+	};
+}

To change the order of TraceFilter registration, please set the +spring.sleuth.web.filter-order property.

54.5 Custom SA tag in Zipkin

Sometimes you want to create a manual Span that will wrap a call to an external service which is not instrumented. +What you can do is to create a span with the peer.service tag that will contain a value of the service that you want to call. +Below you can see an example of a call to Redis that is wrapped in such a span.

org.springframework.cloud.sleuth.Span newSpan = tracer.createSpan("redis");
+try {
+	newSpan.tag("redis.op", "get");
+	newSpan.tag("lc", "redis");
+	newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_SEND);
+	// call redis service e.g
+	// return (SomeObj) redisTemplate.opsForHash().get("MYHASH", someObjKey);
+} finally {
+	newSpan.tag("peer.service", "redisService");
+	newSpan.tag("peer.ipv4", "1.2.3.4");
+	newSpan.tag("peer.port", "1234");
+	newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_RECV);
+	tracer.close(newSpan);
+}
[Important]Important

Remember not to add both peer.service tag and the SA tag! You have to add only peer.service.

54.6 Custom service name

By default Sleuth assumes that when you send a span to Zipkin, you want the span’s service name + to be equal to spring.application.name value. That’s not always the case though. There + are situations in which you want to explicitly provide a different service name for all spans coming + from your application. To achieve that it’s enough to just pass the following property + to your application to override that value (example for foo service name):

spring.zipkin.service.name: foo

54.7 Customization of reported spans

Before reporting spans to e.g. Zipkin you can be interested in modifying that span in some way. + You can achieve that by using the SpanAdjuster interface.

Example of usage:

In Sleuth we’re generating spans with a fixed name. Some users want to modify the name depending on values +of tags. Implementation of the SpanAdjuster interface can be used to alter that name. Example:

@Bean
+SpanAdjuster customSpanAdjuster() {
+    return span -> span.toBuilder().name(scrub(span.getName())).build();
+}

This will lead in changing the name of the reported span just before it gets sent to Zipkin.

[Important]Important

Your SpanReporter should inject the SpanAdjuster and + allow span manipulation before the actual reporting is done.

54.8 Host locator

In order to define the host that is corresponding to a particular span we need to resolve the host name +and port. The default approach is to take it from server properties. If those for some reason are not set +then we’re trying to retrieve the host name from the network interfaces.

If you have the discovery client enabled and prefer to retrieve the host address from the registered +instance in a service registry then you have to set the property (it’s applicable for both HTTP and +Stream based span reporting).

spring.zipkin.locator.discovery.enabled: true
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53. Managing spans with annotations Home 55. Sending spans to Zipkin
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43. Customizing the Message Broker
Prev Part VI. Spring Cloud Bus Next

43. Customizing the Message Broker

Spring Cloud Bus uses +Spring Cloud Stream to +broadcast the messages so to get messages to flow you only need to +include the binder implementation of your choice in the +classpath. There are convenient starters specifically for the bus with +AMQP (RabbitMQ) and Kafka +(spring-cloud-starter-bus-[amqp,kafka]). Generally speaking +Spring Cloud Stream relies on Spring Boot autoconfiguration +conventions for configuring middleware, so for instance the AMQP +broker address can be changed with spring.rabbitmq.* +configuration properties. Spring Cloud Bus has a handful of native +configuration properties in spring.cloud.bus.* +(e.g. spring.cloud.bus.destination is the name of the topic to use +the the externall middleware). Normally the defaults will suffice.

To lean more about how to customize the message broker settings +consult the Spring Cloud Stream documentation.

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42. Application Context ID must be unique Home 44. Tracing Bus Events
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113. Deploying a Packaged Function
Prev Part XV. Spring Cloud Function Next

113. Deploying a Packaged Function

Spring Cloud Function provides a "deployer" library that allows you to launch a jar file (or exploded archive, or set of jar files) with an isolated class loader and expose the functions defined in it. This is quite a powerful tool that would allow you to, for instance, adapt a function to a range of different input-output adapters without changing the target jar file. Serverless platforms often have this kind of feature built in, so you could see it as a building block for a function invoker in such a platform (indeed the Riff Java function invoker uses this library).

The standard entry point of the API is the Spring configuration annotation @EnableFunctionDeployer. If that is used in a Spring Boot application the deployer kicks in and looks for some configuration to tell it where to find the function jar. At a minimum the user has to provide a function.location which is a URL or resource location for the archive containing the functions. It can optionally use a maven: prefix to locate the artifact via a dependency lookup (see FunctionProperties for complete details). A Spring Boot application is bootstrapped from the jar file, using the MANIFEST.MF to locate a start class, so that a standard Spring Boot fat jar works well, for example. If the target jar can be launched successfully then the result is a function registered in the main application’s FunctionCatalog. The registered function can be applied by code in the main application, even though it was created in an isolated class loader (by deault).

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112. Standalone Streaming Applications Home 114. Dynamic Compilation
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82. Discovery
Prev Part XII. Spring Cloud for Cloud Foundry Next

82. Discovery

Here’s a Spring Cloud app with Cloud Foundry discovery:

app.groovy.  +

@Grab('org.springframework.cloud:spring-cloud-cloudfoundry')
+@RestController
+@EnableDiscoveryClient
+class Application {
+
+  @Autowired
+  DiscoveryClient client
+
+  @RequestMapping('/')
+  String home() {
+    'Hello from ' + client.getLocalServiceInstance()
+  }
+
+}

+

If you run it without any service bindings:

$ spring jar app.jar app.groovy
+$ cf push -p app.jar

It will show its app name in the home page.

The DiscoveryClient can lists all the apps in a space, according to +the credentials it is authenticated with, where the space defaults to +the one the client is running in (if any). If neither org nor space +are configured, they default per the user’s profile in Cloud Foundry.

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Part XII. Spring Cloud for Cloud Foundry Home 83. Single Sign On
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114. Dynamic Compilation
Prev Part XV. Spring Cloud Function Next

114. Dynamic Compilation

There is a sample app that uses the function compiler to create a +function from a configuration property. The vanilla "function-sample" +also has that feature. And there are some scripts that you can run to +see the compilation happening at run time. To run these examples, +change into the scripts directory:

cd scripts

Also, start a RabbitMQ server locally (e.g. execute rabbitmq-server).

Start the Function Registry Service:

./function-registry.sh

Register a Function:

./registerFunction.sh -n uppercase -f "f->f.map(s->s.toString().toUpperCase())"

Run a REST Microservice using that Function:

./web.sh -f uppercase -p 9000
+curl -H "Content-Type: text/plain" -H "Accept: text/plain" localhost:9000/uppercase -d foo

Register a Supplier:

./registerSupplier.sh -n words -f "()->Flux.just(\"foo\",\"bar\")"

Run a REST Microservice using that Supplier:

./web.sh -s words -p 9001
+curl -H "Accept: application/json" localhost:9001/words

Register a Consumer:

./registerConsumer.sh -n print -t String -f "System.out::println"

Run a REST Microservice using that Consumer:

./web.sh -c print -p 9002
+curl -X POST -H "Content-Type: text/plain" -d foo localhost:9002/print

Run Stream Processing Microservices:

First register a streaming words supplier:

./registerSupplier.sh -n wordstream -f "()->Flux.interval(Duration.ofMillis(1000)).map(i->\"message-\"+i)"

Then start the source (supplier), processor (function), and sink (consumer) apps +(in reverse order):

./stream.sh -p 9103 -i uppercaseWords -c print
+./stream.sh -p 9102 -i words -f uppercase -o uppercaseWords
+./stream.sh -p 9101 -s wordstream -o words

The output will appear in the console of the sink app (one message per second, converted to uppercase):

MESSAGE-0
+MESSAGE-1
+MESSAGE-2
+MESSAGE-3
+MESSAGE-4
+MESSAGE-5
+MESSAGE-6
+MESSAGE-7
+MESSAGE-8
+MESSAGE-9
+...
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113. Deploying a Packaged Function Home 115. Serverless Platform Adapters
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8. Embedding the Config Server
Prev Part II. Spring Cloud Config Next

8. Embedding the Config Server

The Config Server runs best as a standalone application, but if you +need to you can embed it in another application. Just use the +@EnableConfigServer annotation. An optional property that can be +useful in this case is spring.cloud.config.server.bootstrap which is +a flag to indicate that the server should configure itself from its +own remote repository. The flag is off by default because it can delay +startup, but when embedded in another application it makes sense to +initialize the same way as any other application.

[Note]Note

It should be obvious, but remember that if you use the bootstrap +flag the config server will need to have its name and repository URI +configured in bootstrap.yml.

To change the location of the server endpoints you can (optionally) +set spring.cloud.config.server.prefix, e.g. "/config", to serve the +resources under a prefix. The prefix should start but not end with a +"/". It is applied to the @RequestMappings in the Config Server +(i.e. underneath the Spring Boot prefixes server.servletPath and +server.contextPath).

If you want to read the configuration for an application directly from +the backend repository (instead of from the config server) that’s +basically an embedded config server with no endpoints. You can switch +off the endpoints entirely if you don’t use the @EnableConfigServer +annotation (just set spring.cloud.config.server.bootstrap=true).

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7. Serving Plain Text Home 9. Push Notifications and Spring Cloud Bus
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78. Encryption and Decryption
Prev Part X. Spring Boot Cloud CLI Next

78. Encryption and Decryption

The Spring Cloud CLI comes with an "encrypt" and a "decrypt" +command. Both accept arguments in the same form with a key specified +as a mandatory "--key", e.g.

$ spring encrypt mysecret --key foo
+682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+$ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+mysecret

To use a key in a file (e.g. an RSA public key for encyption) prepend +the key value with "@" and provide the file path, e.g.

$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub
+AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+...
Prev Up Next
77. Writing Groovy Scripts and Running Applications Home Part XI. Spring Cloud Security
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18. External Configuration: Archaius
Prev Part III. Spring Cloud Netflix Next

18. External Configuration: Archaius

Archaius is the Netflix client side configuration library. It is the library used by all of the Netflix OSS components for configuration. Archaius is an extension of the Apache Commons Configuration project. It allows updates to configuration by either polling a source for changes or for a source to push changes to the client. Archaius uses Dynamic<Type>Property classes as handles to properties.

Archaius Example.  +

class ArchaiusTest {
+    DynamicStringProperty myprop = DynamicPropertyFactory
+            .getInstance()
+            .getStringProperty("my.prop");
+
+    void doSomething() {
+        OtherClass.someMethod(myprop.get());
+    }
+}

+

Archaius has its own set of configuration files and loading priorities. Spring applications should generally not use Archaius directly, but the need to configure the Netflix tools natively remains. Spring Cloud has a Spring Environment Bridge so Archaius can read properties from the Spring Environment. This allows Spring Boot projects to use the normal configuration toolchain, while allowing them to configure the Netflix tools, for the most part, as documented.

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17. Declarative REST Client: Feign Home 19. Router and Filter: Zuul
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1. Features
Prev   Next

1. Features

Spring Cloud focuses on providing good out of box experience for typical use cases +and extensibility mechanism to cover others.

  • Distributed/versioned configuration
  • Service registration and discovery
  • Routing
  • Service-to-service calls
  • Load balancing
  • Circuit Breakers
  • Distributed messaging
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 Home Part I. Cloud Native Applications
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48. Features
Prev Part VII. Spring Cloud Sleuth Next

48. Features

  • Adds trace and span ids to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator. Example logs:

    2016-02-02 15:30:57.902  INFO [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ...
+2016-02-02 15:30:58.372 ERROR [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ...
+2016-02-02 15:31:01.936  INFO [bar,46ab0d418373cbc9,46ab0d418373cbc9,false] 23030 --- [nio-8081-exec-4] ...

    notice the [appname,traceId,spanId,exportable] entries from the MDC:

    • spanId - the id of a specific operation that took place
    • appname - the name of the application that logged the span
    • traceId - the id of the latency graph that contains the span
    • exportable - whether the log should be exported to Zipkin or not. When would you like the span not to be +exportable? In the case in which you want to wrap some operation in a Span and have it written to the logs +only.
  • Provides an abstraction over common distributed tracing data models: traces, spans (forming a DAG), annotations, +key-value annotations. Loosely based on HTrace, but Zipkin (Dapper) compatible.

  • Sleuth records timing information to aid in latency analysis. Using sleuth, you can pinpoint causes of +latency in your applications. Sleuth is written to not log too much, and to not cause your production application to crash.

    • propagates structural data about your call-graph in-band, and the rest out-of-band.
    • includes opinionated instrumentation of layers such as HTTP
    • includes sampling policy to manage volume
    • can report to a Zipkin system for query and visualization
  • Instruments common ingress and egress points from Spring applications (servlet filter, async endpoints, +rest template, scheduled actions, message channels, zuul filters, feign client).
  • Sleuth includes default logic to join a trace across http or messaging boundaries. For example, http propagation +works via Zipkin-compatible request headers. This propagation logic is defined and customized via +SpanInjector and SpanExtractor implementations.
  • Sleuth gives you the possibility to propagate context (also known as baggage) between processes. That means that if you set on a Span +a baggage element then it will be sent downstream either via HTTP or messaging to other processes.
  • Provides a way to create / continue spans and add tags and logs via annotations.
  • Provides simple metrics of accepted / dropped spans.

  • If spring-cloud-sleuth-zipkin is on the classpath then the app will generate and collect Zipkin-compatible traces. +By default it sends them via HTTP to a Zipkin server on localhost (port 9411). +Configure the location of the service using spring.zipkin.baseUrl.

    • If you depend on spring-rabbit or spring-kafka your app will send traces to a broker instead of http.
    • Note: spring-cloud-sleuth-stream is deprecated and should no longer be used.
[Important]Important

If using Zipkin, configure the percentage of spans exported using spring.sleuth.sampler.percentage +(default 0.1, i.e. 10%). Otherwise you might think that Sleuth is not working cause it’s omitting some spans.

[Note]Note

the SLF4J MDC is always set and logback users will immediately see the trace and span ids in logs per the example + above. Other logging systems have to configure their own formatter to get the same result. The default is + logging.pattern.level set to %5p [${spring.zipkin.service.name:${spring.application.name:-}},%X{X-B3-TraceId:-},%X{X-B3-SpanId:-},%X{X-Span-Export:-}] + (this is a Spring Boot feature for logback users). + This means that if you’re not using SLF4J this pattern WILL NOT be automatically applied.

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47. Additional resources Home 49. Sampling
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110. Function Catalog and Flexible Function Signatures
Prev Part XV. Spring Cloud Function Next

110. Function Catalog and Flexible Function Signatures

One of the main features of Spring Cloud Function is to adapt and +support a range of type signatures for user-defined functions. So +users can supply a bean of type Function<String,String>, for +instance, and the FunctionCatalog will wrap it into a +Function<Flux<String>,Flux<String>>. Users don’t normally have to +care about the FunctionCatalog at all, but it is useful to know what +kind of functions are supported in user code.

Generally speaking users can expect that if they write a function for +a plain old Java type (or primitive wrapper), then the function +catalog will wrap it to a Flux of the same type. If the user writes +a function using Message (from spring-messaging) it will receive and +transmit headers from any adapter that supports key-value metadata +(e.g. HTTP headers). Here are the details.

User FunctionCatalog Registration 

Function<S,T>

Function<Flux<S>, Flux<T>>

 

Function<Message<S>,Message<T>>

Function<Flux<Message<S>>, Flux<Message<T>>>

 

Function<Flux<S>, Flux<T>>

Function<Flux<S>, Flux<T>> (pass through)

 

Supplier<T>

Supplier<Flux<T>>

 

Supplier<Flux<T>>

Supplier<Flux<T>>

 

Consumer<T>

Function<Flux<T>, Mono<Void>>

 

Consumer<Message<T>>

Function<Flux<Message<T>>, Mono<Void>>

 

Consumer<Flux<T>>

Consumer<Flux<T>>

 

Consumer is a little bit special because it has a void return type, +which implies blocking, at least potentially. Most likely you will not +need to write Consumer<Flux<?>>, but if you do need to do that, +remember to subscribe to the input flux. If you declare a Consumer +of a non publisher type (which is normal), it will be converted to a +function that returns a publisher, so that it can be subscribed to in +a controlled way.

A function catalog can contain a Supplier and a Function (or +Consumer) with the same name (like a GET and a POST to the same +resource). It can even contain a Consumer<Flux<>> with the same name +as a Function, but it cannot contain a Consumer<T> and a +Function<T,S> with the same name when T is not a Publisher +because the consumer would be converted to a Function and only one +of them can be registered.

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109. Building and Running a Function Home 111. Standalone Web Applications
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36. Getting Started
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36. Getting Started

To get started with creating Spring Cloud Stream applications, visit the Spring Initializr and create a new Maven project named "GreetingSource". +Select Spring Boot {supported-spring-boot-version} in the dropdown. +In the Search for dependencies text box type Stream Rabbit or Stream Kafka depending on what binder you want to use.

Next, create a new class, GreetingSource, in the same package as the GreetingSourceApplication class. +Give it the following code:

import org.springframework.cloud.stream.annotation.EnableBinding;
+import org.springframework.cloud.stream.messaging.Source;
+import org.springframework.integration.annotation.InboundChannelAdapter;
+
+@EnableBinding(Source.class)
+public class GreetingSource {
+
+    @InboundChannelAdapter(Source.OUTPUT)
+    public String greet() {
+        return "hello world " + System.currentTimeMillis();
+    }
+}

The @EnableBinding annotation is what triggers the creation of Spring Integration infrastructure components. +Specifically, it will create a Kafka connection factory, a Kafka outbound channel adapter, and the message channel defined inside the Source interface:

public interface Source {
+
+  String OUTPUT = "output";
+
+  @Output(Source.OUTPUT)
+  MessageChannel output();
+
+}

The auto-configuration also creates a default poller, so that the greet() method will be invoked once per second. +The standard Spring Integration @InboundChannelAdapter annotation sends a message to the source’s output channel, using the return value as the payload of the message.

To test-drive this setup, run a Kafka message broker. +An easy way to do this is to use a Docker image:

# On OS X
+$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=`docker-machine ip \`docker-machine active\`` --env ADVERTISED_PORT=9092 spotify/kafka
+
+# On Linux
+$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=localhost --env ADVERTISED_PORT=9092 spotify/kafka

Build the application:

./mvnw clean package

The consumer application is coded in a similar manner. +Go back to Initializr and create another project, named LoggingSink. +Then create a new class, LoggingSink, in the same package as the class LoggingSinkApplication and with the following code:

import org.springframework.cloud.stream.annotation.EnableBinding;
+import org.springframework.cloud.stream.annotation.StreamListener;
+import org.springframework.cloud.stream.messaging.Sink;
+
+@EnableBinding(Sink.class)
+public class LoggingSink {
+
+    @StreamListener(Sink.INPUT)
+    public void log(String message) {
+        System.out.println(message);
+    }
+}

Build the application:

./mvnw clean package

To connect the GreetingSource application to the LoggingSink application, each application must share the same destination name. +Starting up both applications as shown below, you will see the consumer application printing "hello world" and a timestamp to the console:

cd GreetingSource
+java -jar target/GreetingSource-0.0.1-SNAPSHOT.jar --spring.cloud.stream.bindings.output.destination=mydest
+
+cd LoggingSink
+java -jar target/LoggingSink-0.0.1-SNAPSHOT.jar --server.port=8090 --spring.cloud.stream.bindings.input.destination=mydest

(The different server port prevents collisions of the HTTP port used to service the Spring Boot Actuator endpoints in the two applications.)

The output of the LoggingSink application will look something like the following:

[           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8090 (http)
+[           main] com.example.LoggingSinkApplication       : Started LoggingSinkApplication in 6.828 seconds (JVM running for 7.371)
+hello world 1458595076731
+hello world 1458595077732
+hello world 1458595078733
+hello world 1458595079734
+hello world 1458595080735

36.1 Deploying Stream applications on CloudFoundry

On CloudFoundry services are usually exposed via a special environment variable called VCAP_SERVICES.

When configuring your binder connections, you can use the values from an environment variable as explained on the dataflow cloudfoundry server docs.

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35. Samples Home Part V. Binder Implementations
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108. Getting Started
Prev Part XV. Spring Cloud Function Next

108. Getting Started

Build from the command line (and "install" the samples):

$ ./mvnw clean install

(If you like to YOLO add -DskipTests.)

Run one of the samples, e.g.

$ java -jar spring-cloud-function-samples/function-sample/target/*.jar

This runs the app and exposes its functions over HTTP, so you can +convert a string to uppercase, like this:

$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d Hello
+HELLO

You can convert multiple strings (a Flux<String>) by separating them +with new lines

$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d 'Hello
+> World'
+HELLOWORLD

(You can use QJ in a terminal to insert a new line in a literal +string like that.)

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107. Introduction Home 109. Building and Running a Function
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33. Health Indicator
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33. Health Indicator

Spring Cloud Stream provides a health indicator for binders. +It is registered under the name binders and can be enabled or disabled by setting the management.health.binders.enabled property.

By default management.health.binders.enabled is set to false. +Setting management.health.binders.enabled to true enables the health indicator, allowing you to access the /health endpoint to retrieve the binder health indicators.

Health indicators are binder-specific and certain binder implementations may not necessarily provide a health indicator.

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32. Testing Home 34. Metrics Emitter
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23. HTTP Clients
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23. HTTP Clients

Spring Cloud Netflix will automatically create the HTTP client used by Ribbon, Feign, and +Zuul for you. However you can also provide your own HTTP clients customized how you please +yourself. To do this you can either create a bean of type ClosableHttpClient if you +are using the Apache Http Cient, or OkHttpClient if you are using OK HTTP.

[Note]Note

When you create your own HTTP client you are also responsible for implementing +the correct connection management strategies for these clients. Doing this improperly +can result in resource management issues.

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22. Metrics: Spectator, Servo, and Atlas Home Part IV. Spring Cloud Stream
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15. Hystrix Timeouts And Ribbon Clients
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15. Hystrix Timeouts And Ribbon Clients

When using Hystrix commands that wrap Ribbon clients you want to make sure your Hystrix timeout +is configured to be longer than the configured Ribbon timeout, including any potential +retries that might be made. For example, if your Ribbon connection timeout is one second and +the Ribbon client might retry the request three times, than your Hystrix timeout should +be slightly more than three seconds.

15.1 How to Include Hystrix Dashboard

To include the Hystrix Dashboard in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-hystrix-dashboard. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

To run the Hystrix Dashboard annotate your Spring Boot main class with @EnableHystrixDashboard. You then visit /hystrix and point the dashboard to an individual instances /hystrix.stream endpoint in a Hystrix client application.

[Note]Note

When connecting to a /hystrix.stream endpoint which uses HTTPS the certificate used by the server +must be trusted by the JVM. If the certificate is not trusted you must import the certificate into the JVM +in order for the Hystrix Dashboard to make a successful connection to the stream endpoint.

15.2 Turbine

Looking at an individual instances Hystrix data is not very useful in terms of the overall health of the system. Turbine is an application that aggregates all of the relevant /hystrix.stream endpoints into a combined /turbine.stream for use in the Hystrix Dashboard. Individual instances are located via Eureka. Running Turbine is as simple as annotating your main class with the @EnableTurbine annotation (e.g. using spring-cloud-starter-netflix-turbine to set up the classpath). All of the documented configuration properties from the Turbine 1 wiki apply. The only difference is that the turbine.instanceUrlSuffix does not need the port prepended as this is handled automatically unless turbine.instanceInsertPort=false.

[Note]Note

By default, Turbine looks for the /hystrix.stream endpoint on a registered instance by looking up its hostName and port entries in Eureka, then appending /hystrix.stream to it. +If the instance’s metadata contains management.port, it will be used instead of the port value for the /hystrix.stream endpoint. +By default, metadata entry management.port is equal to the management.port configuration property, it can be overridden though with following configuration:

eureka:
+  instance:
+    metadata-map:
+      management.port: ${management.port:8081}

The configuration key turbine.appConfig is a list of eureka serviceIds that turbine will use to lookup instances. The turbine stream is then used in the Hystrix dashboard using a url that looks like: https://my.turbine.sever:8080/turbine.stream?cluster=CLUSTERNAME (the cluster parameter can be omitted if the name is "default"). The cluster parameter must match an entry in turbine.aggregator.clusterConfig. Values returned from eureka are uppercase, thus we expect this example to work if there is an app registered with Eureka called "customers":

turbine:
+  aggregator:
+    clusterConfig: CUSTOMERS
+  appConfig: customers

If you need to customize which cluster names should be used by Turbine (you don’t want to store cluster names in +turbine.aggregator.clusterConfig configuration) provide a bean of type TurbineClustersProvider.

The clusterName can be customized by a SPEL expression in turbine.clusterNameExpression with root an instance of InstanceInfo. The default value is appName, which means that the Eureka serviceId ends up as the cluster key (i.e. the InstanceInfo for customers has an appName of "CUSTOMERS"). A different example would be turbine.clusterNameExpression=aSGName, which would get the cluster name from the AWS ASG name. Another example:

turbine:
+  aggregator:
+    clusterConfig: SYSTEM,USER
+  appConfig: customers,stores,ui,admin
+  clusterNameExpression: metadata['cluster']

In this case, the cluster name from 4 services is pulled from their metadata map, and is expected to have values that include "SYSTEM" and "USER".

To use the "default" cluster for all apps you need a string literal expression (with single quotes, and escaped with double quotes if it is in YAML as well):

turbine:
+  appConfig: customers,stores
+  clusterNameExpression: "'default'"

Spring Cloud provides a spring-cloud-starter-netflix-turbine that has all the dependencies you need to get a Turbine server running. Just create a Spring Boot application and annotate it with @EnableTurbine.

[Note]Note

by default Spring Cloud allows Turbine to use the host and port to allow multiple processes per host, per cluster. If you want the native Netflix behaviour built into Turbine that does not allow multiple processes per host, per cluster (the key to the instance id is the hostname), then set the property turbine.combineHostPort=false.

15.3 Turbine Stream

In some environments (e.g. in a PaaS setting), the classic Turbine model of pulling metrics from all the distributed Hystrix commands doesn’t work. In that case you might want to have your Hystrix commands push metrics to Turbine, and Spring Cloud enables that with messaging. All you need to do on the client is add a dependency to spring-cloud-netflix-hystrix-stream and the spring-cloud-starter-stream-* of your choice (see Spring Cloud Stream documentation for details on the brokers, and how to configure the client credentials, but it should work out of the box for a local broker).

On the server side Just create a Spring Boot application and annotate it with @EnableTurbineStream and by default it will come up on port 8989 (point your Hystrix dashboard to that port, any path). You can customize the port using either server.port or turbine.stream.port. If you have spring-boot-starter-web and spring-boot-starter-actuator on the classpath as well, then you can open up the Actuator endpoints on a separate port (with Tomcat by default) by providing a management.port which is different.

You can then point the Hystrix Dashboard to the Turbine Stream Server instead of individual Hystrix streams. If Turbine Stream is running on port 8989 on myhost, then put http://myhost:8989 in the stream input field in the Hystrix Dashboard. Circuits will be prefixed by their respective serviceId, followed by a dot, then the circuit name.

Spring Cloud provides a spring-cloud-starter-netflix-turbine-stream that has all the dependencies you need to get a Turbine Stream server running - just add the Stream binder of your choice, e.g. spring-cloud-starter-stream-rabbit. You need Java 8 to run the app because it is Netty-based.

Turbine Stream server also supports the cluster parameter. +Unlike Turbine server, Turbine Stream uses eureka serviceIds as cluster names and these are not configurable.

If Turbine Stream server is running on port 8989 on my.turbine.server and you have two eureka serviceIds customers and products in your environment, the following URLs will be available on your Turbine Stream server. default and empty cluster name will provide all metrics that Turbine Stream server receives.

https://my.turbine.sever:8989/turbine.stream?cluster=customers
+https://my.turbine.sever:8989/turbine.stream?cluster=products
+https://my.turbine.sever:8989/turbine.stream?cluster=default
+https://my.turbine.sever:8989/turbine.stream

So, you can use eureka serviceIds as cluster names for your Turbine dashboard (or any compatible dashboard). +You don’t need to configure any properties like turbine.appConfig, turbine.clusterNameExpression and turbine.aggregator.clusterConfig for your Turbine Stream server.

[Note]Note

Turbine Stream server gathers all metrics from the configured input channel with Spring Cloud Stream. It means that it doesn’t gather Hystrix metrics actively from each instance. It just can provide metrics that were already gathered into the input channel by each instance.

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14. Circuit Breaker: Hystrix Dashboard Home 16. Client Side Load Balancer: Ribbon
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75. Installation
Prev Part X. Spring Boot Cloud CLI Next

75. Installation

To install, make +sure you have +Spring Boot CLI +(1.5.2 or better):

$ spring version
+Spring CLI v1.5.4.RELEASE

E.g. for SDKMan users

$ sdk install springboot 1.5.4.RELEASE
+$ sdk use springboot 1.5.4.RELEASE

and install the Spring Cloud plugin

$ mvn install
+$ spring install org.springframework.cloud:spring-cloud-cli:1.4.0.BUILD-SNAPSHOT
[Important]Important

Prerequisites: to use the encryption and decryption features +you need the full-strength JCE installed in your JVM (it’s not there by default). +You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" +from Oracle, and follow instructions for installation (essentially replace the 2 policy files +in the JRE lib/security directory with the ones that you downloaded).

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Part X. Spring Boot Cloud CLI Home 76. Running Spring Cloud Services in Development
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50. Instrumentation
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50. Instrumentation

Spring Cloud Sleuth instruments all your Spring application +automatically, so you shouldn’t have to do anything to activate +it. The instrumentation is added using a variety of technologies +according to the stack that is available, e.g. for a servlet web +application we use a Filter, and for Spring Integration we use +ChannelInterceptors.

You can customize the keys used in span tags. To limit the volume of +span data, by default an HTTP request will be tagged only with a +handful of metadata like the status code, host and URL. You can add +request headers by configuring spring.sleuth.keys.http.headers (a +list of header names).

[Note]Note

Remember that tags are only collected and exported if there is a +Sampler that allows it (by default there is not, so there is no +danger of accidentally collecting too much data without configuring +something).

[Note]Note

Currently the instrumentation in Spring Cloud Sleuth is eager - it means that +we’re actively trying to pass the tracing context between threads. Also timing events +are captured even when sleuth isn’t exporting data to a tracing system. +This approach may change in the future towards being lazy on this matter.

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49. Sampling Home 51. Span lifecycle
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58. Integrations
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58. Integrations

58.1 Runnable and Callable

If you’re wrapping your logic in Runnable or Callable it’s enough to wrap those classes in their Sleuth representative.

Example for Runnable:

Runnable runnable = new Runnable() {
+	@Override
+	public void run() {
+		// do some work
+	}
+
+	@Override
+	public String toString() {
+		return "spanNameFromToStringMethod";
+	}
+};
+// Manual `TraceRunnable` creation with explicit "calculateTax" Span name
+Runnable traceRunnable = new TraceRunnable(tracer, spanNamer, runnable, "calculateTax");
+// Wrapping `Runnable` with `Tracer`. The Span name will be taken either from the
+// `@SpanName` annotation or from `toString` method
+Runnable traceRunnableFromTracer = tracer.wrap(runnable);

Example for Callable:

Callable<String> callable = new Callable<String>() {
+	@Override
+	public String call() throws Exception {
+		return someLogic();
+	}
+
+	@Override
+	public String toString() {
+		return "spanNameFromToStringMethod";
+	}
+};
+// Manual `TraceCallable` creation with explicit "calculateTax" Span name
+Callable<String> traceCallable = new TraceCallable<>(tracer, spanNamer, callable, "calculateTax");
+// Wrapping `Callable` with `Tracer`. The Span name will be taken either from the
+// `@SpanName` annotation or from `toString` method
+Callable<String> traceCallableFromTracer = tracer.wrap(callable);

That way you will ensure that a new Span is created and closed for each execution.

58.2 Hystrix

58.2.1 Custom Concurrency Strategy

We’re registering a custom HystrixConcurrencyStrategy +that wraps all Callable instances into their Sleuth representative - +the TraceCallable. The strategy either starts or continues a span depending on the fact whether tracing was already going +on before the Hystrix command was called. To disable the custom Hystrix Concurrency Strategy set the spring.sleuth.hystrix.strategy.enabled to false.

58.2.2 Manual Command setting

Assuming that you have the following HystrixCommand:

HystrixCommand<String> hystrixCommand = new HystrixCommand<String>(setter) {
+	@Override
+	protected String run() throws Exception {
+		return someLogic();
+	}
+};

In order to pass the tracing information you have to wrap the same logic in the Sleuth version of the HystrixCommand which is the +TraceCommand:

TraceCommand<String> traceCommand = new TraceCommand<String>(tracer, traceKeys, setter) {
+	@Override
+	public String doRun() throws Exception {
+		return someLogic();
+	}
+};

58.3 RxJava

We’re registering a custom RxJavaSchedulersHook +that wraps all Action0 instances into their Sleuth representative - +the TraceAction. The hook either starts or continues a span depending on the fact whether tracing was already going +on before the Action was scheduled. To disable the custom RxJavaSchedulersHook set the spring.sleuth.rxjava.schedulers.hook.enabled to false.

You can define a list of regular expressions for thread names, for which you don’t want a Span to be created. Just provide a comma separated list +of regular expressions in the spring.sleuth.rxjava.schedulers.ignoredthreads property.

58.4 HTTP integration

Features from this section can be disabled by providing the spring.sleuth.web.enabled property with value equal to false.

58.4.1 HTTP Filter

Via the TraceFilter all sampled incoming requests result in creation of a Span. That Span’s name is http: + the path to which + the request was sent. E.g. if the request was sent to /foo/bar then the name will be http:/foo/bar. You can configure which URIs you would + like to skip via the spring.sleuth.web.skipPattern property. If you have ManagementServerProperties on classpath then + its value of contextPath gets appended to the provided skip pattern.

58.4.2 HandlerInterceptor

Since we want the span names to be precise we’re using a TraceHandlerInterceptor that either wraps an + existing HandlerInterceptor or is added directly to the list of existing HandlerInterceptors. The + TraceHandlerInterceptor adds a special request attribute to the given HttpServletRequest. If the + the TraceFilter doesn’t see this attribute set it will create a "fallback" span which is an additional + span created on the server side so that the trace is presented properly in the UI. Seeing that most likely + signifies that there is a missing instrumentation. In that case please file an issue in Spring Cloud Sleuth.

58.4.3 Async Servlet support

If your controller returns a Callable or a WebAsyncTask Spring Cloud Sleuth will continue the existing span instead of creating a new one.

58.5 HTTP client integration

58.5.1 Synchronous Rest Template

We’re injecting a RestTemplate interceptor that ensures that all the tracing information is passed to the requests. Each time a +call is made a new Span is created. It gets closed upon receiving the response. In order to block the synchronous RestTemplate features +just set spring.sleuth.web.client.enabled to false.

[Important]Important

You have to register RestTemplate as a bean so that the interceptors will get injected. +If you create a RestTemplate instance with a new keyword then the instrumentation WILL NOT work.

58.5.2 Asynchronous Rest Template

[Important]Important

A traced version of an AsyncRestTemplate bean is registered for you out of the box. If you +have your own bean you have to wrap it in a TraceAsyncRestTemplate representation. The best solution +is to only customize the ClientHttpRequestFactory and / or AsyncClientHttpRequestFactory. +If you have your own AsyncRestTemplate and you don’t wrap it your calls WILL NOT GET TRACED.

Custom instrumentation is set to create and close Spans upon sending and receiving requests. You can customize the ClientHttpRequestFactory +and the AsyncClientHttpRequestFactory by registering your beans. Remember to use tracing compatible implementations (e.g. don’t forget to +wrap ThreadPoolTaskScheduler in a TraceAsyncListenableTaskExecutor). Example of custom request factories:

@EnableAutoConfiguration
+@Configuration
+public static class TestConfiguration {
+
+	@Bean
+	ClientHttpRequestFactory mySyncClientFactory() {
+		return new MySyncClientHttpRequestFactory();
+	}
+
+	@Bean
+	AsyncClientHttpRequestFactory myAsyncClientFactory() {
+		return new MyAsyncClientHttpRequestFactory();
+	}
+}

To block the AsyncRestTemplate features set spring.sleuth.web.async.client.enabled to false. +To disable creation of the default TraceAsyncClientHttpRequestFactoryWrapper set spring.sleuth.web.async.client.factory.enabled +to false. If you don’t want to create AsyncRestClient at all set spring.sleuth.web.async.client.template.enabled to false.

Multiple Asynchronous Rest Templates

Sometimes you need to use multiple implementations of Asynchronous Rest Template. In the following snippet you +can see an example of how to set up such a custom AsyncRestTemplate.

@Configuration
+@EnableAutoConfiguration
+static class Config {
+	@Autowired Tracer tracer;
+	@Autowired HttpTraceKeysInjector httpTraceKeysInjector;
+	@Autowired HttpSpanInjector spanInjector;
+
+	@Bean(name = "customAsyncRestTemplate")
+	public AsyncRestTemplate traceAsyncRestTemplate(@Qualifier("customHttpRequestFactoryWrapper")
+			TraceAsyncClientHttpRequestFactoryWrapper wrapper, ErrorParser errorParser) {
+		return new TraceAsyncRestTemplate(wrapper, this.tracer, errorParser);
+	}
+
+	@Bean(name = "customHttpRequestFactoryWrapper")
+	public TraceAsyncClientHttpRequestFactoryWrapper traceAsyncClientHttpRequestFactory() {
+		return new TraceAsyncClientHttpRequestFactoryWrapper(this.tracer,
+				this.spanInjector,
+				asyncClientFactory(),
+				clientHttpRequestFactory(),
+				this.httpTraceKeysInjector);
+	}
+
+	private ClientHttpRequestFactory clientHttpRequestFactory() {
+		ClientHttpRequestFactory clientHttpRequestFactory = new CustomClientHttpRequestFactory();
+		//CUSTOMIZE HERE
+		return clientHttpRequestFactory;
+	}
+
+	private AsyncClientHttpRequestFactory asyncClientFactory() {
+		AsyncClientHttpRequestFactory factory = new CustomAsyncClientHttpRequestFactory();
+		//CUSTOMIZE HERE
+		return factory;
+	}
+}

58.5.3 Traverson

If you’re using the Traverson library +it’s enough for you to inject a RestTemplate as a bean into your Traverson object. Since RestTemplate +is already intercepted, you will get full support of tracing in your client. Below you can find a pseudo code +of how to do that:

@Autowired RestTemplate restTemplate;
+
+Traverson traverson = new Traverson(URI.create("http://some/address"),
+    MediaType.APPLICATION_JSON, MediaType.APPLICATION_JSON_UTF8).setRestOperations(restTemplate);
+// use Traverson

58.6 Feign

By default Spring Cloud Sleuth provides integration with feign via the TraceFeignClientAutoConfiguration. You can disable it entirely +by setting spring.sleuth.feign.enabled to false. If you do so then no Feign related instrumentation will take place.

Part of Feign instrumentation is done via a FeignBeanPostProcessor. You can disable it by providing the spring.sleuth.feign.processor.enabled equal to false. +If you set it like this then Spring Cloud Sleuth will not instrument any of your custom Feign components. All the default instrumentation +however will be still there.

58.7 Asynchronous communication

58.7.1 @Async annotated methods

In Spring Cloud Sleuth we’re instrumenting async related components so that the tracing information is passed between threads. +You can disable this behaviour by setting the value of spring.sleuth.async.enabled to false.

If you annotate your method with @Async then we’ll automatically create a new Span with the following characteristics:

  • if the method is annotated with @SpanName then the value of the annotation will be the Span’s name
  • if the method is not annotated with @SpanName the Span name will be the annotated method name
  • the Span will be tagged with that method’s class name and the method name too

58.7.2 @Scheduled annotated methods

In Spring Cloud Sleuth we’re instrumenting scheduled method execution so that the tracing information is passed between threads. You can disable this behaviour +by setting the value of spring.sleuth.scheduled.enabled to false.

If you annotate your method with @Scheduled then we’ll automatically create a new Span with the following characteristics:

  • the Span name will be the annotated method name
  • the Span will be tagged with that method’s class name and the method name too

If you want to skip Span creation for some @Scheduled annotated classes you can set the +spring.sleuth.scheduled.skipPattern with a regular expression that will match the fully qualified name of the +@Scheduled annotated class.

[Tip]Tip

If you are using spring-cloud-sleuth-stream and spring-cloud-netflix-hystrix-stream together, Span will be created for each Hystrix metrics and sent to Zipkin. This may be annoying. You can prevent this by setting spring.sleuth.scheduled.skipPattern=org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask

58.7.3 Executor, ExecutorService and ScheduledExecutorService

We’re providing LazyTraceExecutor, TraceableExecutorService and TraceableScheduledExecutorService. Those implementations +are creating Spans each time a new task is submitted, invoked or scheduled.

Here you can see an example of how to pass tracing information with TraceableExecutorService when working with CompletableFuture:

CompletableFuture<Long> completableFuture = CompletableFuture.supplyAsync(() -> {
+	// perform some logic
+	return 1_000_000L;
+}, new TraceableExecutorService(executorService,
+		// 'calculateTax' explicitly names the span - this param is optional
+		tracer, traceKeys, spanNamer, "calculateTax"));
[Important]Important

Sleuth doesn’t work with parallelStream() out of the box. If you want +to have the tracing information propagated through the stream you have to use the +approach with supplyAsync(…​) as presented above.

Customization of Executors

Sometimes you need to set up a custom instance of the AsyncExecutor. In the following snippet you +can see an example of how to set up such a custom Executor.

@Configuration
+@EnableAutoConfiguration
+@EnableAsync
+static class CustomExecutorConfig extends AsyncConfigurerSupport {
+
+	@Autowired BeanFactory beanFactory;
+
+	@Override public Executor getAsyncExecutor() {
+		ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+		// CUSTOMIZE HERE
+		executor.setCorePoolSize(7);
+		executor.setMaxPoolSize(42);
+		executor.setQueueCapacity(11);
+		executor.setThreadNamePrefix("MyExecutor-");
+		// DON'T FORGET TO INITIALIZE
+		executor.initialize();
+		return new LazyTraceExecutor(this.beanFactory, executor);
+	}
+}

58.8 Messaging

Spring Cloud Sleuth integrates with Spring Integration. It creates spans for publish and +subscribe events. To disable Spring Integration instrumentation, set spring.sleuth.integration.enabled to false.

You can provide the spring.sleuth.integration.patterns pattern to explicitly +provide the names of channels that you want to include for tracing. By default all channels +are included.

[Important]Important

When using the Executor to build a Spring Integration IntegrationFlow remember to use the untraced version of the Executor. +Decorating Spring Integration Executor Channel with TraceableExecutorService will cause the spans to be improperly closed.

58.9 Zuul

We’re registering Zuul filters to propagate the tracing information (the request header is enriched with tracing data). +To disable Zuul support set the spring.sleuth.zuul.enabled property to false.

58.10 Spring Cloud Function

Sleuth works out of the box with Spring Cloud Function. Since functions +might be short living, it’s best to make the Zipkin span reporting synchronous. +Just define a Reporter<Span> bean as presented below:

@Configuration
+class ReporterConfiguration {
+	@Bean
+	public Reporter<Span> reporter(
+			SpanMetricReporter spanMetricReporter,
+			ZipkinProperties zipkin,
+			Sender sender
+	) {
+		final AsyncReporter<Span> reporter = AsyncReporter.builder(sender)
+				.queuedMaxSpans(1000)
+				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
+				.metrics(new ReporterMetricsAdapter(spanMetricReporter))
+				.build(zipkin.getEncoder());
+		return new Reporter<Span>() {
+			@Override public void report(Span span) {
+				reporter.report(span);
+				// make the reporter synchronous
+				reporter.flush();
+			}
+		};
+	}
+}
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57. Metrics Home 59. Running examples
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31. Inter-Application Communication
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31. Inter-Application Communication

31.1 Connecting Multiple Application Instances

While Spring Cloud Stream makes it easy for individual Spring Boot applications to connect to messaging systems, the typical scenario for Spring Cloud Stream is the creation of multi-application pipelines, where microservice applications send data to each other. +You can achieve this scenario by correlating the input and output destinations of adjacent applications.

Supposing that a design calls for the Time Source application to send data to the Log Sink application, you can use a common destination named ticktock for bindings within both applications.

Time Source (that has the channel name output) will set the following property:

spring.cloud.stream.bindings.output.destination=ticktock

Log Sink (that has the channel name input) will set the following property:

spring.cloud.stream.bindings.input.destination=ticktock

31.2 Instance Index and Instance Count

When scaling up Spring Cloud Stream applications, each instance can receive information about how many other instances of the same application exist and what its own instance index is. +Spring Cloud Stream does this through the spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex properties. +For example, if there are three instances of a HDFS sink application, all three instances will have spring.cloud.stream.instanceCount set to 3, and the individual applications will have spring.cloud.stream.instanceIndex set to 0, 1, and 2, respectively.

When Spring Cloud Stream applications are deployed via Spring Cloud Data Flow, these properties are configured automatically; when Spring Cloud Stream applications are launched independently, these properties must be set correctly. +By default, spring.cloud.stream.instanceCount is 1, and spring.cloud.stream.instanceIndex is 0.

In a scaled-up scenario, correct configuration of these two properties is important for addressing partitioning behavior (see below) in general, and the two properties are always required by certain binders (e.g., the Kafka binder) in order to ensure that data are split correctly across multiple consumer instances.

31.3 Partitioning

31.3.1 Configuring Output Bindings for Partitioning

An output binding is configured to send partitioned data by setting one and only one of its partitionKeyExpression or partitionKeyExtractorClass properties, as well as its partitionCount property. +For example, the following is a valid and typical configuration:

spring.cloud.stream.bindings.output.producer.partitionKeyExpression=payload.id
+spring.cloud.stream.bindings.output.producer.partitionCount=5

Based on the above example configuration, data will be sent to the target partition using the following logic.

A partition key’s value is calculated for each message sent to a partitioned output channel based on the partitionKeyExpression. +The partitionKeyExpression is a SpEL expression which is evaluated against the outbound message for extracting the partitioning key.

If a SpEL expression is not sufficient for your needs, you can instead calculate the partition key value by setting the property partitionKeyExtractorClass to a class which implements the org.springframework.cloud.stream.binder.PartitionKeyExtractorStrategy interface. +While the SpEL expression should usually suffice, more complex cases may use the custom implementation strategy. +In that case, the property 'partitionKeyExtractorClass' can be set as follows:

spring.cloud.stream.bindings.output.producer.partitionKeyExtractorClass=com.example.MyKeyExtractor
+spring.cloud.stream.bindings.output.producer.partitionCount=5

Once the message key is calculated, the partition selection process will determine the target partition as a value between 0 and partitionCount - 1. +The default calculation, applicable in most scenarios, is based on the formula key.hashCode() % partitionCount. +This can be customized on the binding, either by setting a SpEL expression to be evaluated against the 'key' (via the partitionSelectorExpression property) or by setting a org.springframework.cloud.stream.binder.PartitionSelectorStrategy implementation (via the partitionSelectorClass property).

The binding level properties for 'partitionSelectorExpression' and 'partitionSelectorClass' can be specified similar to the way 'partitionKeyExpression' and 'partitionKeyExtractorClass' properties are specified in the above examples. +Additional properties can be configured for more advanced scenarios, as described in the following section.

Spring-managed custom PartitionKeyExtractorClass implementations

In the example above, a custom strategy such as MyKeyExtractor is instantiated by the Spring Cloud Stream directly. +In some cases, it is necessary for such a custom strategy implementation to be created as a Spring bean, for being able to be managed by Spring, so that it can perform dependency injection, property binding, etc. +This can be done by configuring it as a @Bean in the application context and using the fully qualified class name as the bean’s name, as in the following example.

@Bean(name="com.example.MyKeyExtractor")
+public MyKeyExtractor extractor() {
+    return new MyKeyExtractor();
+}

As a Spring bean, the custom strategy benefits from the full lifecycle of a Spring bean. +For example, if the implementation need access to the application context directly, it can make implement 'ApplicationContextAware'.

Configuring Input Bindings for Partitioning

An input binding (with the channel name input) is configured to receive partitioned data by setting its partitioned property, as well as the instanceIndex and instanceCount properties on the application itself, as in the following example:

spring.cloud.stream.bindings.input.consumer.partitioned=true
+spring.cloud.stream.instanceIndex=3
+spring.cloud.stream.instanceCount=5

The instanceCount value represents the total number of application instances between which the data need to be partitioned, and the instanceIndex must be a unique value across the multiple instances, between 0 and instanceCount - 1. +The instance index helps each application instance to identify the unique partition (or, in the case of Kafka, the partition set) from which it receives data. +It is important to set both values correctly in order to ensure that all of the data is consumed and that the application instances receive mutually exclusive datasets.

While a scenario which using multiple instances for partitioned data processing may be complex to set up in a standalone case, Spring Cloud Dataflow can simplify the process significantly by populating both the input and output values correctly as well as relying on the runtime infrastructure to provide information about the instance index and instance count.

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30. Schema Evolution Support Home 32. Testing
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24. Introducing Spring Cloud Stream
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24. Introducing Spring Cloud Stream

Spring Cloud Stream is a framework for building message-driven microservice applications. +Spring Cloud Stream builds upon Spring Boot to create standalone, production-grade Spring applications, and uses Spring Integration to provide connectivity to message brokers. +It provides opinionated configuration of middleware from several vendors, introducing the concepts of persistent publish-subscribe semantics, consumer groups, and partitions.

You can add the @EnableBinding annotation to your application to get immediate connectivity to a message broker, and you can add @StreamListener to a method to cause it to receive events for stream processing. +The following is a simple sink application which receives external messages.

@SpringBootApplication
+@EnableBinding(Sink.class)
+public class VoteRecordingSinkApplication {
+
+  public static void main(String[] args) {
+    SpringApplication.run(VoteRecordingSinkApplication.class, args);
+  }
+
+  @StreamListener(Sink.INPUT)
+  public void processVote(Vote vote) {
+      votingService.recordVote(vote);
+  }
+}

The @EnableBinding annotation takes one or more interfaces as parameters (in this case, the parameter is a single Sink interface). +An interface declares input and/or output channels. +Spring Cloud Stream provides the interfaces Source, Sink, and Processor; you can also define your own interfaces.

The following is the definition of the Sink interface:

public interface Sink {
+  String INPUT = "input";
+
+  @Input(Sink.INPUT)
+  SubscribableChannel input();
+}

The @Input annotation identifies an input channel, through which received messages enter the application; the @Output annotation identifies an output channel, through which published messages leave the application. +The @Input and @Output annotations can take a channel name as a parameter; if a name is not provided, the name of the annotated method will be used.

Spring Cloud Stream will create an implementation of the interface for you. +You can use this in the application by autowiring it, as in the following example of a test case.

@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = VoteRecordingSinkApplication.class)
+@WebAppConfiguration
+@DirtiesContext
+public class StreamApplicationTests {
+
+  @Autowired
+  private Sink sink;
+
+  @Test
+  public void contextLoads() {
+    assertNotNull(this.sink.input());
+  }
+}
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Part IV. Spring Cloud Stream Home 25. Main Concepts
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46. Introduction
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46. Introduction

Spring Cloud Sleuth implements a distributed tracing solution for Spring Cloud.

46.1 Terminology

Spring Cloud Sleuth borrows Dapper’s terminology.

Span: The basic unit of work. For example, sending an RPC is a new span, as is sending a response to an +RPC. Span’s are identified by a unique 64-bit ID for the span and another 64-bit ID for the trace the span +is a part of. Spans also have other data, such as descriptions, timestamped events, key-value +annotations (tags), the ID of the span that caused them, and process ID’s (normally IP address).

Spans are started and stopped, and they keep track of their timing information. Once you create a +span, you must stop it at some point in the future.

[Tip]Tip

The initial span that starts a trace is called a root span. The value of span id +of that span is equal to trace id.

Trace: A set of spans forming a tree-like structure. For example, if you are running a distributed +big-data store, a trace might be formed by a put request.

Annotation: is used to record existence of an event in time. Some of the core annotations used to define +the start and stop of a request are:

  • cs - Client Sent - The client has made a request. This annotation depicts the start of the span.
  • sr - Server Received - The server side got the request and will start processing it. +If one subtracts the cs timestamp from this timestamp one will receive the network latency.
  • ss - Server Sent - Annotated upon completion of request processing (when the response +got sent back to the client). If one subtracts the sr timestamp from this timestamp one +will receive the time needed by the server side to process the request.
  • cr - Client Received - Signifies the end of the span. The client has successfully received the +response from the server side. If one subtracts the cs timestamp from this timestamp one +will receive the whole time needed by the client to receive the response from the server.

Visualization of what Span and Trace will look in a system together with the Zipkin annotations:

Trace Info propagation

Each color of a note signifies a span (7 spans - from A to G). If you have such information in the note:

Trace Id = X
+Span Id = D
+Client Sent

That means that the current span has Trace-Id set to X, Span-Id set to D. It also has emitted + Client Sent event.

This is how the visualization of the parent / child relationship of spans would look like:

Parent child relationship

46.2 Purpose

In the following sections the example from the image above will be taken into consideration.

46.2.1 Distributed tracing with Zipkin

Altogether there are 7 spans . If you go to traces in Zipkin you will see this number in the second trace:

Traces

However if you pick a particular trace then you will see 4 spans:

Traces Info propagation
[Note]Note

When picking a particular trace you will see merged spans. That means that if there were 2 spans sent to +Zipkin with Server Received and Server Sent / Client Received and Client Sent +annotations then they will presented as a single span.

Why is there a difference between the 7 and 4 spans in this case?

  • 2 spans come from http:/start span. It has the Server Received (SR) and Server Sent (SS) annotations.
  • 2 spans come from the RPC call from service1 to service2 to the http:/foo endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service1 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service2 side. Physically there are 2 spans but they form 1 logical span related to an RPC call.
  • 2 spans come from the RPC call from service2 to service3 to the http:/bar endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service2 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service3 side. Physically there are 2 spans but they form 1 logical span related to an RPC call.
  • 2 spans come from the RPC call from service2 to service4 to the http:/baz endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service2 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service4 side. Physically there are 2 spans but they form 1 logical span related to an RPC call.

So if we count the physical spans we have 1 from http:/start, 2 from service1 calling service2, 2 form service2 +calling service3 and 2 from service2 calling service4. Altogether 7 spans.

Logically we see the information of Total Spans: 4 because we have 1 span related to the incoming request +to service1 and 3 spans related to RPC calls.

46.2.2 Visualizing errors

Zipkin allows you to visualize errors in your trace. When an exception was thrown and wasn’t caught then we’re +setting proper tags on the span which Zipkin can properly colorize. You could see in the list of traces one + trace that was in red color. That’s because there was an exception thrown.

If you click that trace then you’ll see a similar picture

Error Traces

Then if you click on one of the spans you’ll see the following

Error Traces Info propagation

As you can see you can easily see the reason for an error and the whole stacktrace related to it.

46.2.3 Live examples

Figure 46.1. Click Pivotal Web Services icon to see it live!

Zipkin deployed on Pivotal Web Services

The dependency graph in Zipkin would look like this:

Dependencies

Figure 46.2. Click Pivotal Web Services icon to see it live!

Zipkin deployed on Pivotal Web Services

46.2.4 Log correlation

When grepping the logs of those four applications by trace id equal to e.g. 2485ec27856c56f4 one would get the following:

service1.log:2016-02-26 11:15:47.561  INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application   : Hello from service1. Calling service2
+service2.log:2016-02-26 11:15:47.710  INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application   : Hello from service2. Calling service3 and then service4
+service3.log:2016-02-26 11:15:47.895  INFO [service3,2485ec27856c56f4,1210be13194bfe5,true] 68060 --- [nio-8083-exec-1] i.s.c.sleuth.docs.service3.Application   : Hello from service3
+service2.log:2016-02-26 11:15:47.924  INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application   : Got response from service3 [Hello from service3]
+service4.log:2016-02-26 11:15:48.134  INFO [service4,2485ec27856c56f4,1b1845262ffba49d,true] 68061 --- [nio-8084-exec-1] i.s.c.sleuth.docs.service4.Application   : Hello from service4
+service2.log:2016-02-26 11:15:48.156  INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application   : Got response from service4 [Hello from service4]
+service1.log:2016-02-26 11:15:48.182  INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application   : Got response from service2 [Hello from service2, response from service3 [Hello from service3] and from service4 [Hello from service4]]

If you’re using a log aggregating tool like Kibana, +Splunk etc. you can order the events that took place. An example of +Kibana would look like this:

Log correlation with Kibana

If you want to use Logstash here is the Grok pattern for Logstash:

filter {
+       # pattern matching logback pattern
+       grok {
+              match => { "message" => "%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
+       }
+}
[Note]Note

If you want to use Grok together with the logs from Cloud Foundry you have to use this pattern:

filter {
+       # pattern matching logback pattern
+       grok {
+              match => { "message" => "(?m)OUT\s+%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
+       }
+}

JSON Logback with Logstash

Often you do not want to store your logs in a text file but in a JSON file that Logstash can immediately pick. To do that you have to do the following (for readability +we’re passing the dependencies in the groupId:artifactId:version notation.

Dependencies setup

  • Ensure that Logback is on the classpath (ch.qos.logback:logback-core)
  • Add Logstash Logback encode - example for version 4.6 : net.logstash.logback:logstash-logback-encoder:4.6

Logback setup

Below you can find an example of a Logback configuration (file named logback-spring.xml) that:

  • logs information from the application in a JSON format to a build/${spring.application.name}.json file
  • has commented out two additional appenders - console and standard log file
  • has the same logging pattern as the one presented in the previous section
<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+	<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
+	​
+	<springProperty scope="context" name="springAppName" source="spring.application.name"/>
+	<!-- Example for logging into the build folder of your project -->
+	<property name="LOG_FILE" value="${BUILD_FOLDER:-build}/${springAppName}"/>​
+
+	<!-- You can override this to have a custom pattern -->
+	<property name="CONSOLE_LOG_PATTERN"
+			  value="%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}"/>
+
+	<!-- Appender to log to console -->
+	<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
+		<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
+			<!-- Minimum logging level to be presented in the console logs-->
+			<level>DEBUG</level>
+		</filter>
+		<encoder>
+			<pattern>${CONSOLE_LOG_PATTERN}</pattern>
+			<charset>utf8</charset>
+		</encoder>
+	</appender>
+
+	<!-- Appender to log to file -->​
+	<appender name="flatfile" class="ch.qos.logback.core.rolling.RollingFileAppender">
+		<file>${LOG_FILE}</file>
+		<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+			<fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.gz</fileNamePattern>
+			<maxHistory>7</maxHistory>
+		</rollingPolicy>
+		<encoder>
+			<pattern>${CONSOLE_LOG_PATTERN}</pattern>
+			<charset>utf8</charset>
+		</encoder>
+	</appender>
+	​
+	<!-- Appender to log to file in a JSON format -->
+	<appender name="logstash" class="ch.qos.logback.core.rolling.RollingFileAppender">
+		<file>${LOG_FILE}.json</file>
+		<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+			<fileNamePattern>${LOG_FILE}.json.%d{yyyy-MM-dd}.gz</fileNamePattern>
+			<maxHistory>7</maxHistory>
+		</rollingPolicy>
+		<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
+			<providers>
+				<timestamp>
+					<timeZone>UTC</timeZone>
+				</timestamp>
+				<pattern>
+					<pattern>
+						{
+						"severity": "%level",
+						"service": "${springAppName:-}",
+						"trace": "%X{X-B3-TraceId:-}",
+						"span": "%X{X-B3-SpanId:-}",
+						"parent": "%X{X-B3-ParentSpanId:-}",
+						"exportable": "%X{X-Span-Export:-}",
+						"pid": "${PID:-}",
+						"thread": "%thread",
+						"class": "%logger{40}",
+						"rest": "%message"
+						}
+					</pattern>
+				</pattern>
+			</providers>
+		</encoder>
+	</appender>
+	​
+	<root level="INFO">
+		<appender-ref ref="console"/>
+		<!-- uncomment this to have also JSON logs -->
+		<!--<appender-ref ref="logstash"/>-->
+		<!--<appender-ref ref="flatfile"/>-->
+	</root>
+</configuration>
[Note]Note

If you’re using a custom logback-spring.xml then you have to pass the spring.application.name in +bootstrap instead of application property file. Otherwise your custom logback file won’t read the property properly.

46.2.5 Propagating Span Context

The span context is the state that must get propagated to any child Spans across process boundaries. +Part of the Span Context is the Baggage. The trace and span IDs are a required part of the span context. +Baggage is an optional part.

Baggage is a set of key:value pairs stored in the span context. Baggage travels together with the trace +and is attached to every span. Spring Cloud Sleuth will understand that a header is baggage related if the HTTP + header is prefixed with baggage- and for messaging it starts with baggage_.

[Important]Important

There’s currently no limitation of the count or size of baggage items. However, keep in mind that +too many can decrease system throughput or increase RPC latency. In extreme cases, it could crash the app due +to exceeding transport-level message or header capacity.

Example of setting baggage on a span:

Span initialSpan = this.tracer.createSpan("span");
+initialSpan.setBaggageItem("foo", "bar");
+initialSpan.setBaggageItem("UPPER_CASE", "someValue");

Baggage vs. Span Tags

Baggage travels with the trace (i.e. every child span contains the baggage of its parent). Zipkin has no knowledge of +baggage and will not even receive that information.

Tags are attached to a specific span - they are presented for that particular span only. However you +can search by tag to find the trace, where there exists a span having the searched tag value.

If you want to be able to lookup a span based on baggage, you should add corresponding entry as a tag in the root span.

@Autowired Tracer tracer;
+
+Span span = tracer.getCurrentSpan();
+String baggageKey = "key";
+String baggageValue = "foo";
+span.setBaggageItem(baggageKey, baggageValue);
+tracer.addTag(baggageKey, baggageValue);

46.3 Adding to the project

[Important]Important

To ensure that your application name is properly displayed in Zipkin + set the spring.application.name property in bootstrap.yml.

46.3.1 Only Sleuth (log correlation)

If you want to profit only from Spring Cloud Sleuth without the Zipkin integration just add +the spring-cloud-starter-sleuth module to your project.

Maven.  +

<dependencyManagement> 1
+         <dependencies>
+             <dependency>
+                 <groupId>org.springframework.cloud</groupId>
+                 <artifactId>spring-cloud-dependencies</artifactId>
+                 <version>${release.train.version}</version>
+                 <type>pom</type>
+                 <scope>import</scope>
+             </dependency>
+         </dependencies>
+   </dependencyManagement>
+
+   <dependency> 2
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-starter-sleuth</artifactId>
+   </dependency>

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-sleuth

Gradle.  +

dependencyManagement { 1
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
+    }
+}
+
+dependencies { 2
+    compile "org.springframework.cloud:spring-cloud-starter-sleuth"
+}

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-sleuth

46.3.2 Sleuth with Zipkin via HTTP

If you want both Sleuth and Zipkin just add the spring-cloud-starter-zipkin dependency.

Maven.  +

<dependencyManagement> 1
+         <dependencies>
+             <dependency>
+                 <groupId>org.springframework.cloud</groupId>
+                 <artifactId>spring-cloud-dependencies</artifactId>
+                 <version>${release.train.version}</version>
+                 <type>pom</type>
+                 <scope>import</scope>
+             </dependency>
+         </dependencies>
+   </dependencyManagement>
+
+   <dependency> 2
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-starter-zipkin</artifactId>
+   </dependency>

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin

Gradle.  +

dependencyManagement { 1
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
+    }
+}
+
+dependencies { 2
+    compile "org.springframework.cloud:spring-cloud-starter-zipkin"
+}

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin

46.3.3 Sleuth with Zipkin via RabbitMQ or Kafka

If you want to use RabbitMQ or Kafka instead of http, add the spring-rabbit or spring-kafka +dependencies. The default destination name is zipkin.

Note: spring-cloud-sleuth-stream is deprecated and incompatible with these destinations

If you want Sleuth over RabbitMQ add the spring-cloud-starter-zipkin and spring-rabbit +dependencies.

Maven.  +

<dependencyManagement> 1
+         <dependencies>
+             <dependency>
+                 <groupId>org.springframework.cloud</groupId>
+                 <artifactId>spring-cloud-dependencies</artifactId>
+                 <version>${release.train.version}</version>
+                 <type>pom</type>
+                 <scope>import</scope>
+             </dependency>
+         </dependencies>
+   </dependencyManagement>
+
+   <dependency> 2
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-starter-zipkin</artifactId>
+   </dependency>
+   <dependency> 3
+       <groupId>org.springframework.amqp</groupId>
+       <artifactId>spring-rabbit</artifactId>
+   </dependency>

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin - that way all dependent dependencies will be downloaded

3

To automatically configure rabbit, simply add the spring-rabbit dependency

Gradle.  +

dependencyManagement { 1
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
+    }
+}
+
+dependencies {
+    compile "org.springframework.cloud:spring-cloud-starter-zipkin" 2
+    compile "org.springframework.amqp:spring-rabbit" 3
+}

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin - that way all dependent dependencies will be downloaded

3

To automatically configure rabbit, simply add the spring-rabbit dependency

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Part VII. Spring Cloud Sleuth Home 47. Additional resources
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107. Introduction
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107. Introduction

Spring Cloud Function is a project with the following high-level goals:

  • Promote the implementation of business logic via functions.
  • Decouple the development lifecycle of business logic from any specific runtime target so that the same code can run as a web endpoint, a stream processor, or a task.
  • Support a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS).
  • Enable Spring Boot features (auto-configuration, dependency injection, metrics) on serverless providers.

It abstracts away all of the transport details and +infrastructure, allowing the developer to keep all the familiar tools +and processes, and focus firmly on business logic.

Here’s a complete, executable, testable Spring Boot application +(implementing a simple string manipulation):

@SpringBootApplication
+public class Application {
+
+  @Bean
+  public Function<Flux<String>, Flux<String>> uppercase() {
+    return flux -> flux.map(value -> value.toUpperCase());
+  }
+
+  public static void main(String[] args) {
+    SpringApplication.run(Application.class, args);
+  }
+}

It’s just a Spring Boot application, so it can be built, run and +tested, locally and in a CI build, the same way as any other Spring +Boot application. The Function is from java.util and Flux is a +Reactive Streams Publisher from +Project Reactor. The function can be +accessed over HTTP or messaging.

Spring Cloud Function has 4 main features:

  1. Wrappers for @Beans of type Function, Consumer and +Supplier, exposing them to the outside world as either HTTP +endpoints and/or message stream listeners/publishers with RabbitMQ, Kafka etc.
  2. Compiling strings which are Java function bodies into bytecode, and +then turning them into @Beans that can be wrapped as above.
  3. Deploying a JAR file containing such an application context with an +isolated classloader, so that you can pack them together in a single +JVM.
  4. Adapters for AWS Lambda, Azure, Apache OpenWhisk and possibly other "serverless" service providers.
[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

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Part XV. Spring Cloud Function Home 108. Getting Started
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96. Links
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96. Links

The following links may be helpful when working with Spring Cloud Contract Verifier:

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95. Migrations Home Part XIV. Spring Cloud Vault
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25. Main Concepts
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25. Main Concepts

Spring Cloud Stream provides a number of abstractions and primitives that simplify the writing of message-driven microservice applications. +This section gives an overview of the following:

  • Spring Cloud Stream’s application model
  • The Binder abstraction
  • Persistent publish-subscribe support
  • Consumer group support
  • Partitioning support
  • A pluggable Binder API

25.1 Application Model

A Spring Cloud Stream application consists of a middleware-neutral core. +The application communicates with the outside world through input and output channels injected into it by Spring Cloud Stream. +Channels are connected to external brokers through middleware-specific Binder implementations.

Figure 25.1. Spring Cloud Stream Application

SCSt with binder

25.1.1 Fat JAR

Spring Cloud Stream applications can be run in standalone mode from your IDE for testing. +To run a Spring Cloud Stream application in production, you can create an executable (or "fat") JAR by using the standard Spring Boot tooling provided for Maven or Gradle.

25.2 The Binder Abstraction

Spring Cloud Stream provides Binder implementations for Kafka and Rabbit MQ. +Spring Cloud Stream also includes a TestSupportBinder, which leaves a channel unmodified so that tests can interact with channels directly and reliably assert on what is received. +You can use the extensible API to write your own Binder.

Spring Cloud Stream uses Spring Boot for configuration, and the Binder abstraction makes it possible for a Spring Cloud Stream application to be flexible in how it connects to middleware. +For example, deployers can dynamically choose, at runtime, the destinations (e.g., the Kafka topics or RabbitMQ exchanges) to which channels connect. +Such configuration can be provided through external configuration properties and in any form supported by Spring Boot (including application arguments, environment variables, and application.yml or application.properties files). +In the sink example from the Chapter 24, Introducing Spring Cloud Stream section, setting the application property spring.cloud.stream.bindings.input.destination to raw-sensor-data will cause it to read from the raw-sensor-data Kafka topic, or from a queue bound to the raw-sensor-data RabbitMQ exchange.

Spring Cloud Stream automatically detects and uses a binder found on the classpath. +You can easily use different types of middleware with the same code: just include a different binder at build time. +For more complex use cases, you can also package multiple binders with your application and have it choose the binder, and even whether to use different binders for different channels, at runtime.

25.3 Persistent Publish-Subscribe Support

Communication between applications follows a publish-subscribe model, where data is broadcast through shared topics. +This can be seen in the following figure, which shows a typical deployment for a set of interacting Spring Cloud Stream applications.

Figure 25.2. Spring Cloud Stream Publish-Subscribe

SCSt sensors

Data reported by sensors to an HTTP endpoint is sent to a common destination named raw-sensor-data. +From the destination, it is independently processed by a microservice application that computes time-windowed averages and by another microservice application that ingests the raw data into HDFS. +In order to process the data, both applications declare the topic as their input at runtime.

The publish-subscribe communication model reduces the complexity of both the producer and the consumer, and allows new applications to be added to the topology without disruption of the existing flow. +For example, downstream from the average-calculating application, you can add an application that calculates the highest temperature values for display and monitoring. +You can then add another application that interprets the same flow of averages for fault detection. +Doing all communication through shared topics rather than point-to-point queues reduces coupling between microservices.

While the concept of publish-subscribe messaging is not new, Spring Cloud Stream takes the extra step of making it an opinionated choice for its application model. +By using native middleware support, Spring Cloud Stream also simplifies use of the publish-subscribe model across different platforms.

25.4 Consumer Groups

While the publish-subscribe model makes it easy to connect applications through shared topics, the ability to scale up by creating multiple instances of a given application is equally important. +When doing this, different instances of an application are placed in a competing consumer relationship, where only one of the instances is expected to handle a given message.

Spring Cloud Stream models this behavior through the concept of a consumer group. +(Spring Cloud Stream consumer groups are similar to and inspired by Kafka consumer groups.) +Each consumer binding can use the spring.cloud.stream.bindings.<channelName>.group property to specify a group name. +For the consumers shown in the following figure, this property would be set as spring.cloud.stream.bindings.<channelName>.group=hdfsWrite or spring.cloud.stream.bindings.<channelName>.group=average.

Figure 25.3. Spring Cloud Stream Consumer Groups

SCSt groups

All groups which subscribe to a given destination receive a copy of published data, but only one member of each group receives a given message from that destination. +By default, when a group is not specified, Spring Cloud Stream assigns the application to an anonymous and independent single-member consumer group that is in a publish-subscribe relationship with all other consumer groups.

25.4.1 Durability

Consistent with the opinionated application model of Spring Cloud Stream, consumer group subscriptions are durable. +That is, a binder implementation ensures that group subscriptions are persistent, and once at least one subscription for a group has been created, the group will receive messages, even if they are sent while all applications in the group are stopped.

[Note]Note

Anonymous subscriptions are non-durable by nature. +For some binder implementations (e.g., RabbitMQ), it is possible to have non-durable group subscriptions.

In general, it is preferable to always specify a consumer group when binding an application to a given destination. +When scaling up a Spring Cloud Stream application, you must specify a consumer group for each of its input bindings. +This prevents the application’s instances from receiving duplicate messages (unless that behavior is desired, which is unusual).

25.5 Partitioning Support

Spring Cloud Stream provides support for partitioning data between multiple instances of a given application. +In a partitioned scenario, the physical communication medium (e.g., the broker topic) is viewed as being structured into multiple partitions. +One or more producer application instances send data to multiple consumer application instances and ensure that data identified by common characteristics are processed by the same consumer instance.

Spring Cloud Stream provides a common abstraction for implementing partitioned processing use cases in a uniform fashion. +Partitioning can thus be used whether the broker itself is naturally partitioned (e.g., Kafka) or not (e.g., RabbitMQ).

Figure 25.4. Spring Cloud Stream Partitioning

SCSt partitioning

Partitioning is a critical concept in stateful processing, where it is critiical, for either performance or consistency reasons, to ensure that all related data is processed together. +For example, in the time-windowed average calculation example, it is important that all measurements from any given sensor are processed by the same application instance.

[Note]Note

To set up a partitioned processing scenario, you must configure both the data-producing and the data-consuming ends.

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24. Introducing Spring Cloud Stream Home 26. Programming Model
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53. Managing spans with annotations
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53. Managing spans with annotations

53.1 Rationale

The main arguments for this features are

  • api-agnostic means to collaborate with a span

    • use of annotations allows users to add to a span with no library dependency on a span api. +This allows Sleuth to change its core api less impact to user code.

  • reduced surface area for basic span operations.

    • without this feature one has to use the span api, which has lifecycle commands that +could be used incorrectly. By only exposing scope, tag and log functionality, users can +collaborate without accidentally breaking span lifecycle.

  • collaboration with runtime generated code

    • with libraries such as Spring Data / Feign the implementations of interfaces are generated +at runtime thus span wrapping of objects was tedious. Now you can provide annotations + over interfaces and arguments of those interfaces

53.2 Creating new spans

If you really don’t want to take care of creating local spans manually you can profit from the +@NewSpan annotation. Also we give you the @SpanTag annotation to add tags in an automated +fashion.

Let’s look at some examples of usage.

@NewSpan
+void testMethod();

Annotating the method without any parameter will lead to a creation of a new span whose name +will be equal to annotated method name.

@NewSpan("customNameOnTestMethod4")
+void testMethod4();

If you provide the value in the annotation (either directly or via the name parameter) then +the created span will have the name as the provided value.

// method declaration
+@NewSpan(name = "customNameOnTestMethod5")
+void testMethod5(@SpanTag("testTag") String param);
+
+// and method execution
+this.testBean.testMethod5("test");

You can combine both the name and a tag. Let’s focus on the latter. In this case whatever the value of +the annotated method’s parameter runtime value will be - that will be the value of the tag. In our sample +the tag key will be testTag and the tag value will be test.

@NewSpan(name = "customNameOnTestMethod3")
+@Override
+public void testMethod3() {
+}

You can place the @NewSpan annotation on both the class and an interface. If you override the +interface’s method and provide a different value of the @NewSpan annotation then the most +concrete one wins (in this case customNameOnTestMethod3 will be set).

53.3 Continuing spans

If you want to just add tags and annotations to an existing span it’s enough +to use the @ContinueSpan annotation as presented below. Note that in contrast +with the @NewSpan annotation you can also add logs via the log parameter:

// method declaration
+@ContinueSpan(log = "testMethod11")
+void testMethod11(@SpanTag("testTag11") String param);
+
+// method execution
+this.testBean.testMethod11("test");

That way the span will get continued and:

  • logs with name testMethod11.before and testMethod11.after will be created
  • if an exception will be thrown a log testMethod11.afterFailure will also be created
  • tag with key testTag11 and value test will be created

53.4 More advanced tag setting

There are 3 different ways to add tags to a span. All of them are controlled by the SpanTag annotation. +Precedence is:

  • try with the bean of TagValueResolver type and provided name
  • if one hasn’t provided the bean name, try to evaluate an expression. We’re searching for a TagValueExpressionResolver bean. +The default implementation uses SPEL expression resolution. If we do not find any expression to evaluate, return the toString() +value of the parameter. +IMPORTANT You can only reference properties from the SPEL expression. Method execution is not allowed due to security constraints.
  • if one hasn’t provided any expression to evaluate just return a toString() value of the parameter

53.4.1 Custom extractor

The value of the tag for following method will be computed by an implementation of TagValueResolver interface. +Its class name has to be passed as the value of the resolver attribute.

Having such an annotated method:

@NewSpan
+public void getAnnotationForTagValueResolver(@SpanTag(key = "test", resolver = TagValueResolver.class) String test) {
+}

and such a TagValueResolver bean implementation

@Bean(name = "myCustomTagValueResolver")
+public TagValueResolver tagValueResolver() {
+	return parameter -> "Value from myCustomTagValueResolver";
+}

Will lead to setting of a tag value equal to Value from myCustomTagValueResolver.

53.4.2 Resolving expressions for value

Having such an annotated method:

@NewSpan
+public void getAnnotationForTagValueExpression(@SpanTag(key = "test", expression = "'hello' + ' characters'") String test) {
+}

and no custom implementation of a TagValueExpressionResolver will lead to evaluation of the SPEL expression and a tag with value 4 characters will be set on the span. +If you want to use some other expression resolution mechanism you can create your own implementation +of the bean.

53.4.3 Using toString method

Having such an annotated method:

@NewSpan
+public void getAnnotationForArgumentToString(@SpanTag("test") Long param) {
+}

if executed with a value of 15 will lead to setting of a tag with a String value of "15".

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52. Naming spans Home 54. Customizations
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57. Metrics
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57. Metrics

Currently Spring Cloud Sleuth registers very simple metrics related to spans. +It’s using the Spring Boot’s metrics support +to calculate the number of accepted and dropped spans. Each time a span gets +sent to Zipkin the number of accepted spans will increase. If there’s an error then +the number of dropped spans will get increased.

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56. Span Data as Messages Home 58. Integrations
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34. Metrics Emitter
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34. Metrics Emitter

Spring Cloud Stream provides a module called spring-cloud-stream-metrics that can be used to emit any available metric from Spring Boot metrics endpoint to a named channel. +This module allow operators to collect metrics from stream applications without relying on polling their endpoints.

The module is activated when you set the destination name for metrics binding, e.g. spring.cloud.stream.bindings.applicationMetrics.destination=<DESTINATION_NAME>. +applicationMetrics can be configured in a similar fashion to any other producer binding. +The default contentType setting of applicationMetrics is application/json.

The following properties can be used for customizing the emission of metrics:

spring.cloud.stream.metrics.key
The name of the metric being emitted. Should be an unique value per application.
Default
${spring.application.name:${vcap.application.name:${spring.config.name:application}}}
spring.cloud.stream.metrics.prefix

Prefix string to be prepended to the metrics key.

Default: ``

spring.cloud.stream.metrics.properties

Just like the includes option, it allows white listing application properties that will be added to the metrics payload

Default: null.

A detailed overview of the metrics export process can be found in the Spring Boot reference documentation. +Spring Cloud Stream provides a metric exporter named application that can be configured via regular Spring Boot metrics configuration properties.

The exporter can be configured either by using the global Spring Boot configuration settings for exporters, or by using exporter-specific properties. +For using the global configuration settings, the properties should be prefixed by spring.metric.export (e.g. spring.metric.export.includes=integration**). +These configuration options will apply to all exporters (unless they have been configured differently). +Alternatively, if it is intended to use configuration settings that are different from the other exporters (e.g. for restricting the number of metrics published), the Spring Cloud Stream provided metrics exporter can be configured using the prefix spring.metrics.export.triggers.application (e.g. spring.metrics.export.triggers.application.includes=integration**).

[Note]Note

Due to Spring Boot’s relaxed binding the value of a property being included can be slightly different than the original value.

As a rule of thumb, the metric exporter will attempt to normalize all the properties in a consistent format using the dot notation (e.g. JAVA_HOME becomes java.home).

The goal of normalization is to make downstream consumers of those metrics capable of receiving property names consistently, regardless of how they are set on the monitored application (--spring.application.name or SPRING_APPLICATION_NAME would always yield spring.application.name).

Below is a sample of the data published to the channel in JSON format by the following command:

java -jar time-source.jar \
+    --spring.cloud.stream.bindings.applicationMetrics.destination=someMetrics \
+    --spring.cloud.stream.metrics.properties=spring.application** \
+    --spring.metrics.export.includes=integration.channel.input**,integration.channel.output**

The resulting JSON is:

{
+   "name":"time-source",
+   "metrics":[
+      {
+         "name":"integration.channel.output.errorRate.mean",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.max",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.min",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.stdev",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.count",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendCount",
+         "value":6.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.mean",
+         "value":0.994885872292989,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.max",
+         "value":1.006247080013156,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.min",
+         "value":1.0012035220116378,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.stdev",
+         "value":6.505181111084848E-4,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.count",
+         "value":6.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      }
+   ],
+   "createdTime":"2017-04-11T20:56:35.790Z",
+   "properties":{
+      "spring.application.name":"time-source",
+      "spring.application.index":"0"
+   }
+}
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33. Health Indicator Home 35. Samples
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95. Migrations
Prev Part XIII. Spring Cloud Contract Next

95. Migrations

This section covers migrating from one version of Spring Cloud Contract Verifier to the +next version. It covers the following versions upgrade paths:

95.1 1.0.x → 1.1.x

This section covers upgrading from version 1.0 to version 1.1.

95.1.1 New structure of generated stubs

In 1.1.x we have introduced a change to the structure of generated stubs. If you have +been using the @AutoConfigureWireMock notation to use the stubs from the classpath, +it no longer works. The following example shows how the @AutoConfigureWireMock notation +used to work:

@AutoConfigureWireMock(stubs = "classpath:/customer-stubs/mappings", port = 8084)

You must either change the location of the stubs to: +classpath:…​/META-INF/groupId/artifactId/version/mappings or use the new +classpath-based @AutoConfigureStubRunner, as shown in the following example:

@AutoConfigureWireMock(stubs = "classpath:customer-stubs/META-INF/travel.components/customer-contract/1.0.2-SNAPSHOT/mappings/", port = 8084)

If you do not want to use @AutoConfigureStubRunner and you want to remain with the old +structure, set your plugin tasks accordingly. The following example would work for the +structure presented in the previous snippet.

Maven.  +

<!-- start of pom.xml -->
+
+<properties>
+    <!-- we don't want the verifier to do a jar for us -->
+    <spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip>
+</properties>
+
+<!-- ... -->
+
+<!-- You need to set up the assembly plugin -->
+<build>
+    <plugins>
+        <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-assembly-plugin</artifactId>
+            <executions>
+                <execution>
+                    <id>stub</id>
+                    <phase>prepare-package</phase>
+                    <goals>
+                        <goal>single</goal>
+                    </goals>
+                    <inherited>false</inherited>
+                    <configuration>
+                        <attach>true</attach>
+                        <descriptor>$../../../../src/assembly/stub.xml</descriptor>
+                    </configuration>
+                </execution>
+            </executions>
+        </plugin>
+    </plugins>
+</build>
+<!-- end of pom.xml -->
+
+<!-- start of stub.xml-->
+
+<assembly
+	xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	<id>stubs</id>
+	<formats>
+		<format>jar</format>
+	</formats>
+	<includeBaseDirectory>false</includeBaseDirectory>
+	<fileSets>
+		<fileSet>
+			<directory>${project.build.directory}/snippets/stubs</directory>
+			<outputDirectory>customer-stubs/mappings</outputDirectory>
+			<includes>
+				<include>**/*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>$../../../../src/test/resources/contracts</directory>
+			<outputDirectory>customer-stubs/contracts</outputDirectory>
+			<includes>
+				<include>**/*.groovy</include>
+			</includes>
+		</fileSet>
+	</fileSets>
+</assembly>
+
+<!-- end of stub.xml-->

+

Gradle.  +

task copyStubs(type: Copy, dependsOn: 'generateWireMockClientStubs') {
+//    Preserve directory structure from 1.0.X of spring-cloud-contract
+    from "${project.buildDir}/resources/main/customer-stubs/META-INF/${project.group}/${project.name}/${project.version}"
+    into "${project.buildDir}/resources/main/customer-stubs"
+}

+

95.2 1.1.x → 1.2.x

This section covers upgrading from version 1.1 to version 1.2.

95.2.1 Custom HttpServerStub

HttpServerStub includes a method that was not in version 1.1. The method is +String registeredMappings() If you have classes that implement HttpServerStub, you +now have to implement the registeredMappings() method. It should return a String +representing all mappings available in a single HttpServerStub.

See issue 355 for more +detail.

95.2.2 New packages for generated tests

The flow for setting the generated tests package name will look like this:

  • Set basePackageForTests
  • If basePackageForTests was not set, pick the package from baseClassForTests
  • If baseClassForTests was not set, pick packageWithBaseClasses
  • If nothing got set, pick the default value: +org.springframework.cloud.contract.verifier.tests

See issue 260 for more +detail.

95.2.3 New Methods in TemplateProcessor

In order to add support for fromRequest.path, the following methods had to be added to the +TemplateProcessor interface:

  • path()
  • path(int index)

See issue 388 for more +detail.

95.2.4 RestAssured 3.0

Rest Assured, used in the generated test classes, got bumped to 3.0. If +you manually set versions of Spring Cloud Contract and the release train +you might see the following exception:

Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:testCompile (default-testCompile) on project some-project: Compilation failure: Compilation failure:
+[ERROR] /some/path/SomeClass.java:[4,39] package com.jayway.restassured.response does not exist

This exception will occur due to the fact that the tests got generated with +an old version of plugin and at test execution time you have an incompatible +version of the release train (and vice versa).

Done via issue 267

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94. Spring Cloud Contract WireMock Home 96. Links
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80. More Detail
Prev Part XI. Spring Cloud Security Next

80. More Detail

80.1 Single Sign On

[Note]Note

All of the OAuth2 SSO and resource server features moved to Spring Boot +in version 1.3. You can find documentation in the +Spring Boot user guide.

80.2 Token Relay

A Token Relay is where an OAuth2 consumer acts as a Client and +forwards the incoming token to outgoing resource requests. The +consumer can be a pure Client (like an SSO application) or a Resource +Server.

80.2.1 Client Token Relay

If your app is a user facing OAuth2 client (i.e. has declared +@EnableOAuth2Sso or @EnableOAuth2Client) then it has an +OAuth2ClientContext in request scope from Spring Boot. You can +create your own OAuth2RestTemplate from this context and an +autowired OAuth2ProtectedResourceDetails, and then the context will +always forward the access token downstream, also refreshing the access +token automatically if it expires. (These are features of Spring +Security and Spring Boot.)

[Note]Note

Spring Boot (1.4.1) does not create an +OAuth2ProtectedResourceDetails automatically if you are using +client_credentials tokens. In that case you need to create your own +ClientCredentialsResourceDetails and configure it with +@ConfigurationProperties("security.oauth2.client").

80.2.2 Client Token Relay in Zuul Proxy

If your app also has a +Spring +Cloud Zuul embedded reverse proxy (using @EnableZuulProxy) then you +can ask it to forward OAuth2 access tokens downstream to the services +it is proxying. Thus the SSO app above can be enhanced simply like +this:

app.groovy.  +

@Controller
+@EnableOAuth2Sso
+@EnableZuulProxy
+class Application {
+
+}

+

and it will (in addition to logging the user in and grabbing a token) +pass the authentication token downstream to the /proxy/* +services. If those services are implemented with +@EnableResourceServer then they will get a valid token in the +correct header.

How does it work? The @EnableOAuth2Sso annotation pulls in +spring-cloud-starter-security (which you could do manually in a +traditional app), and that in turn triggers some autoconfiguration for +a ZuulFilter, which itself is activated because Zuul is on the +classpath (via @EnableZuulProxy). The +filter +just extracts an access token from the currently authenticated user, +and puts it in a request header for the downstream requests.

80.2.3 Resource Server Token Relay

If your app has @EnableResourceServer you might want to relay the +incoming token downstream to other services. If you use a +RestTemplate to contact the downstream services then this is just a +matter of how to create the template with the right context.

If your service uses UserInfoTokenServices to authenticate incoming +tokens (i.e. it is using the security.oauth2.user-info-uri +configuration), then you can simply create an OAuth2RestTemplate +using an autowired OAuth2ClientContext (it will be populated by the +authentication process before it hits the backend code). Equivalently +(with Spring Boot 1.4), you could inject a +UserInfoRestTemplateFactory and grab its OAuth2RestTemplate in +your configuration. For example:

MyConfiguration.java.  +

@Bean
+public OAuth2RestTemplate restTemplate(UserInfoRestTemplateFactory factory) {
+    return factory.getUserInfoRestTemplate();
+}

+

This rest template will then have the same OAuth2ClientContext +(request-scoped) that is used by the authentication filter, so you can +use it to send requests with the same access token.

If your app is not using UserInfoTokenServices but is still a client +(i.e. it declares @EnableOAuth2Client or @EnableOAuth2Sso), then +with Spring Security Cloud any OAuth2RestOperations that the user +creates from an @Autowired @OAuth2Context will also forward +tokens. This feature is implemented by default as an MVC handler +interceptor, so it only works in Spring MVC. If you are not using MVC +you could use a custom filter or AOP interceptor wrapping an +AccessTokenContextRelay to provide the same feature.

Here’s a basic +example showing the use of an autowired rest template created +elsewhere ("foo.com" is a Resource Server accepting the same tokens as +the surrounding app):

MyController.java.  +

@Autowired
+private OAuth2RestOperations restTemplate;
+
+@RequestMapping("/relay")
+public String relay() {
+    ResponseEntity<String> response =
+      restTemplate.getForEntity("https://foo.com/bar", String.class);
+    return "Success! (" + response.getBody() + ")";
+}

+

If you don’t want to forward tokens (and that is a valid +choice, since you might want to act as yourself, rather than the +client that sent you the token), then you only need to create your own +OAuth2Context instead of autowiring the default one.

Feign clients will also pick up an interceptor that uses the +OAuth2ClientContext if it is available, so they should also do a +token relay anywhere where a RestTemplate would.

Prev Up Next
79. Quickstart Home 81. Configuring Authentication Downstream of a Zuul Proxy
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52. Naming spans
Prev Part VII. Spring Cloud Sleuth Next

52. Naming spans

Picking a span name is not a trivial task. Span name should depict an operation name. The name should +be low cardinality (e.g. not include identifiers).

Since there is a lot of instrumentation going on some of the span names will be +artificial like:

  • controller-method-name when received by a Controller with a method name conrollerMethodName
  • async for asynchronous operations done via wrapped Callable and Runnable.
  • @Scheduled annotated methods will return the simple name of the class.

Fortunately, for the asynchronous processing you can provide explicit naming.

52.1 @SpanName annotation

You can name the span explicitly via the @SpanName annotation.

@SpanName("calculateTax")
+class TaxCountingRunnable implements Runnable {
+
+	@Override public void run() {
+		// perform logic
+	}
+}

In this case, when processed in the following manner:

Runnable runnable = new TraceRunnable(tracer, spanNamer, new TaxCountingRunnable());
+Future<?> future = executorService.submit(runnable);
+// ... some additional logic ...
+future.get();

The span will be named calculateTax.

52.2 toString() method

It’s pretty rare to create separate classes for Runnable or Callable. Typically one creates an anonymous +instance of those classes. You can’t annotate such classes thus to override that, if there is no @SpanName annotation present, +we’re checking if the class has a custom implementation of the toString() method.

So executing such code:

Runnable runnable = new TraceRunnable(tracer, spanNamer, new Runnable() {
+	@Override public void run() {
+		// perform logic
+	}
+
+	@Override public String toString() {
+		return "calculateTax";
+	}
+});
+Future<?> future = executorService.submit(runnable);
+// ... some additional logic ...
+future.get();

will lead in creating a span named calculateTax.

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51. Span lifecycle Home 53. Managing spans with annotations
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20. Polyglot support with Sidecar
Prev Part III. Spring Cloud Netflix Next

20. Polyglot support with Sidecar

Do you have non-jvm languages you want to take advantage of Eureka, Ribbon and +Config Server? The Spring Cloud Netflix Sidecar was inspired by +Netflix Prana. It includes a simple http api +to get all of the instances (ie host and port) for a given service. You can +also proxy service calls through an embedded Zuul proxy which gets its route +entries from Eureka. The Spring Cloud Config Server can be accessed directly +via host lookup or through the Zuul Proxy. The non-jvm app should implement +a health check so the Sidecar can report to eureka if the app is up or down.

To include Sidecar in your project use the dependency with group org.springframework.cloud +and artifact id spring-cloud-netflix-sidecar.

To enable the Sidecar, create a Spring Boot application with @EnableSidecar. +This annotation includes @EnableCircuitBreaker, @EnableDiscoveryClient, +and @EnableZuulProxy. Run the resulting application on the same host as the +non-jvm application.

To configure the side car add sidecar.port and sidecar.health-uri to application.yml. +The sidecar.port property is the port the non-jvm app is listening on. This +is so the Sidecar can properly register the app with Eureka. The sidecar.health-uri +is a uri accessible on the non-jvm app that mimicks a Spring Boot health +indicator. It should return a json document like the following:

health-uri-document.  +

{
+  "status":"UP"
+}

+

Here is an example application.yml for a Sidecar application:

application.yml.  +

server:
+  port: 5678
+spring:
+  application:
+    name: sidecar
+
+sidecar:
+  port: 8000
+  health-uri: http://localhost:8000/health.json

+

The api for the DiscoveryClient.getInstances() method is /hosts/{serviceId}. +Here is an example response for /hosts/customers that returns two instances on +different hosts. This api is accessible to the non-jvm app (if the sidecar is +on port 5678) at http://localhost:5678/hosts/{serviceId}.

/hosts/customers.  +

[
+    {
+        "host": "myhost",
+        "port": 9000,
+        "uri": "http://myhost:9000",
+        "serviceId": "CUSTOMERS",
+        "secure": false
+    },
+    {
+        "host": "myhost2",
+        "port": 9000,
+        "uri": "http://myhost2:9000",
+        "serviceId": "CUSTOMERS",
+        "secure": false
+    }
+]

+

The Zuul proxy automatically adds routes for each service known in eureka to +/<serviceId>, so the customers service is available at /customers. The +Non-jvm app can access the customer service via http://localhost:5678/customers +(assuming the sidecar is listening on port 5678).

If the Config Server is registered with Eureka, non-jvm application can access +it via the Zuul proxy. If the serviceId of the ConfigServer is configserver +and the Sidecar is on port 5678, then it can be accessed at +http://localhost:5678/configserver

Non-jvm app can take advantage of the Config Server’s ability to return YAML +documents. For example, a call to https://sidecar.local.spring.io:5678/configserver/default-master.yml +might result in a YAML document like the following

eureka:
+  client:
+    serviceUrl:
+      defaultZone: http://localhost:8761/eureka/
+  password: password
+info:
+  description: Spring Cloud Samples
+  url: https://github.com/spring-cloud-samples
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19. Router and Filter: Zuul Home 21. RxJava with Spring MVC
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26. Programming Model
Prev Part IV. Spring Cloud Stream Next

26. Programming Model

This section describes Spring Cloud Stream’s programming model. +Spring Cloud Stream provides a number of predefined annotations for declaring bound input and output channels as well as how to listen to channels.

26.1 Declaring and Binding Channels

26.1.1 Triggering Binding Via @EnableBinding

You can turn a Spring application into a Spring Cloud Stream application by applying the @EnableBinding annotation to one of the application’s configuration classes. +The @EnableBinding annotation itself is meta-annotated with @Configuration and triggers the configuration of Spring Cloud Stream infrastructure:

...
+@Import(...)
+@Configuration
+@EnableIntegration
+public @interface EnableBinding {
+    ...
+    Class<?>[] value() default {};
+}

The @EnableBinding annotation can take as parameters one or more interface classes that contain methods which represent bindable components (typically message channels).

[Note]Note

The @EnableBinding annotation is only required on your Configuration classes, you can provide as many binding interfaces as you need, for instance: @EnableBinding(value={Orders.class, Payment.class}. +Where both Order and Payment interfaces would declare @Input and @Output channels.

26.1.2 @Input and @Output

A Spring Cloud Stream application can have an arbitrary number of input and output channels defined in an interface as @Input and @Output methods:

public interface Barista {
+
+    @Input
+    SubscribableChannel orders();
+
+    @Output
+    MessageChannel hotDrinks();
+
+    @Output
+    MessageChannel coldDrinks();
+}

Using this interface as a parameter to @EnableBinding will trigger the creation of three bound channels named orders, hotDrinks, and coldDrinks, respectively.

@EnableBinding(Barista.class)
+public class CafeConfiguration {
+
+   ...
+}
[Note]Note

In Spring Cloud Stream, the bindable MessageChannel components are the Spring Messaging MessageChannel (for outbound) and its extension SubscribableChannel (for inbound). +Using the same mechanism other bindable components can be supported. +KStream support in Spring Cloud Stream Kafka binder is one such example where KStream is used as inbound/outbound bindable components. +In this documentation, we will continue to refer to MessageChannels as the bindable components.

Customizing Channel Names

Using the @Input and @Output annotations, you can specify a customized channel name for the channel, as shown in the following example:

public interface Barista {
+    ...
+    @Input("inboundOrders")
+    SubscribableChannel orders();
+}

In this example, the created bound channel will be named inboundOrders.

Source, Sink, and Processor

For easy addressing of the most common use cases, which involve either an input channel, an output channel, or both, Spring Cloud Stream provides three predefined interfaces out of the box.

Source can be used for an application which has a single outbound channel.

public interface Source {
+
+  String OUTPUT = "output";
+
+  @Output(Source.OUTPUT)
+  MessageChannel output();
+
+}

Sink can be used for an application which has a single inbound channel.

public interface Sink {
+
+  String INPUT = "input";
+
+  @Input(Sink.INPUT)
+  SubscribableChannel input();
+
+}

Processor can be used for an application which has both an inbound channel and an outbound channel.

public interface Processor extends Source, Sink {
+}

Spring Cloud Stream provides no special handling for any of these interfaces; they are only provided out of the box.

26.1.3 Accessing Bound Channels

Injecting the Bound Interfaces

For each bound interface, Spring Cloud Stream will generate a bean that implements the interface. +Invoking a @Input-annotated or @Output-annotated method of one of these beans will return the relevant bound channel.

The bean in the following example sends a message on the output channel when its hello method is invoked. +It invokes output() on the injected Source bean to retrieve the target channel.

@Component
+public class SendingBean {
+
+    private Source source;
+
+    @Autowired
+    public SendingBean(Source source) {
+        this.source = source;
+    }
+
+    public void sayHello(String name) {
+         source.output().send(MessageBuilder.withPayload(name).build());
+    }
+}

Injecting Channels Directly

Bound channels can be also injected directly:

@Component
+public class SendingBean {
+
+    private MessageChannel output;
+
+    @Autowired
+    public SendingBean(MessageChannel output) {
+        this.output = output;
+    }
+
+    public void sayHello(String name) {
+         output.send(MessageBuilder.withPayload(name).build());
+    }
+}

If the name of the channel is customized on the declaring annotation, that name should be used instead of the method name. +Given the following declaration:

public interface CustomSource {
+    ...
+    @Output("customOutput")
+    MessageChannel output();
+}

The channel will be injected as shown in the following example:

@Component
+public class SendingBean {
+
+    private MessageChannel output;
+
+    @Autowired
+    public SendingBean(@Qualifier("customOutput") MessageChannel output) {
+        this.output = output;
+    }
+
+    public void sayHello(String name) {
+         this.output.send(MessageBuilder.withPayload(name).build());
+    }
+}

26.1.4 Producing and Consuming Messages

You can write a Spring Cloud Stream application using either Spring Integration annotations or Spring Cloud Stream’s @StreamListener annotation. +The @StreamListener annotation is modeled after other Spring Messaging annotations (such as @MessageMapping, @JmsListener, @RabbitListener, etc.) but adds content type management and type coercion features.

Native Spring Integration Support

Because Spring Cloud Stream is based on Spring Integration, Stream completely inherits Integration’s foundation and infrastructure as well as the component itself. +For example, you can attach the output channel of a Source to a MessageSource:

@EnableBinding(Source.class)
+public class TimerSource {
+
+  @Value("${format}")
+  private String format;
+
+  @Bean
+  @InboundChannelAdapter(value = Source.OUTPUT, poller = @Poller(fixedDelay = "${fixedDelay}", maxMessagesPerPoll = "1"))
+  public MessageSource<String> timerMessageSource() {
+    return () -> new GenericMessage<>(new SimpleDateFormat(format).format(new Date()));
+  }
+}

Or you can use a processor’s channels in a transformer:

@EnableBinding(Processor.class)
+public class TransformProcessor {
+  @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
+  public Object transform(String message) {
+    return message.toUpperCase();
+  }
+}
[Note]Note

It’s important to understant that when you consume from the same binding using @StreamListener a pubsub model is used, where each method annotated with @StreamListener receives it’s own copy of the message, each one has its own consumer group. +However, if you share a bindable channel as an input for @Aggregator, @Transformer or @ServiceActivator, those will consume in a competing model, no individual consumer group is created for each subscription.

Spring Integration Error Channel Support

Spring Cloud Stream supports publishing error messages received by the Spring Integration global +error channel. Error messages sent to the errorChannel can be published to a specific destination +at the broker by configuring a binding for the outbound target named error. For example, to +publish error messages to a broker destination named "myErrors", provide the following property: +spring.cloud.stream.bindings.error.destination=myErrors.

Message Channel Binders and Error Channels

Starting with version 1.3, some MessageChannel - based binders publish errors to a discrete error channel for each destination. +In addition, these error channels are bridged to the global Spring Integration errorChannel mentioned above. +You can therefore consume errors for specific destinations and/or for all destinations, using a standard Spring Integration flow (IntegrationFlow, @ServiceActivator, etc).

On the consumer side, the listener thread catches any exceptions and forwards an ErrorMessage to the destination’s error channel. +The payload of the message is a MessagingException with the normal failedMessage and cause properties. +Usually, the raw data received from the broker is included in a header. +For binders that support (and are configured with) a dead letter destination; a MessagePublishingErrorHandler is subscribed to the channel, and the raw data is forwarded to the dead letter destination.

On the producer side; for binders that support some kind of async result after publishing messages (e.g. RabbitMQ, Kafka), you can enable an error channel by setting the …​producer.errorChannelEnabled to true. +The payload of the ErrorMessage depends on the binder implementation but will be a MessagingException with the normal failedMessage property, as well as additional properties about the failure. +Refer to the binder documentation for complete details.

Using @StreamListener for Automatic Content Type Handling

Complementary to its Spring Integration support, Spring Cloud Stream provides its own @StreamListener annotation, modeled after other Spring Messaging annotations (e.g. @MessageMapping, @JmsListener, @RabbitListener, etc.). +The @StreamListener annotation provides a simpler model for handling inbound messages, especially when dealing with use cases that involve content type management and type coercion.

Spring Cloud Stream provides an extensible MessageConverter mechanism for handling data conversion by bound channels and for, in this case, dispatching to methods annotated with @StreamListener. +The following is an example of an application which processes external Vote events:

@EnableBinding(Sink.class)
+public class VoteHandler {
+
+  @Autowired
+  VotingService votingService;
+
+  @StreamListener(Sink.INPUT)
+  public void handle(Vote vote) {
+    votingService.record(vote);
+  }
+}

The distinction between @StreamListener and a Spring Integration @ServiceActivator is seen when considering an inbound Message that has a String payload and a contentType header of application/json. +In the case of @StreamListener, the MessageConverter mechanism will use the contentType header to parse the String payload into a Vote object.

As with other Spring Messaging methods, method arguments can be annotated with @Payload, @Headers and @Header.

[Note]Note

For methods which return data, you must use the @SendTo annotation to specify the output binding destination for data returned by the method:

@EnableBinding(Processor.class)
+public class TransformProcessor {
+
+  @Autowired
+  VotingService votingService;
+
+  @StreamListener(Processor.INPUT)
+  @SendTo(Processor.OUTPUT)
+  public VoteResult handle(Vote vote) {
+    return votingService.record(vote);
+  }
+}

Using @StreamListener for dispatching messages to multiple methods

Since version 1.2, Spring Cloud Stream supports dispatching messages to multiple @StreamListener methods registered on an input channel, based on a condition.

In order to be eligible to support conditional dispatching, a method must satisfy the follow conditions:

  • it must not return a value
  • it must be an individual message handling method (reactive API methods are not supported)

The condition is specified via a SpEL expression in the condition attribute of the annotation and is evaluated for each message. +All the handlers that match the condition will be invoked in the same thread and no assumption must be made about the order in which the invocations take place.

An example of using @StreamListener with dispatching conditions can be seen below. +In this example, all the messages bearing a header type with the value foo will be dispatched to the receiveFoo method, and all the messages bearing a header type with the value bar will be dispatched to the receiveBar method.

@EnableBinding(Sink.class)
+@EnableAutoConfiguration
+public static class TestPojoWithAnnotatedArguments {
+
+    @StreamListener(target = Sink.INPUT, condition = "headers['type']=='foo'")
+    public void receiveFoo(@Payload FooPojo fooPojo) {
+       // handle the message
+    }
+
+    @StreamListener(target = Sink.INPUT, condition = "headers['type']=='bar'")
+    public void receiveBar(@Payload BarPojo barPojo) {
+       // handle the message
+    }
+}
[Note]Note

Dispatching via @StreamListener conditions is only supported for handlers of individual messages, and not for reactive programming support (described below).

26.1.5 Reactive Programming Support

Spring Cloud Stream also supports the use of reactive APIs where incoming and outgoing data is handled as continuous data flows. +Support for reactive APIs is available via the spring-cloud-stream-reactive, which needs to be added explicitly to your project.

The programming model with reactive APIs is declarative, where instead of specifying how each individual message should be handled, you can use operators that describe functional transformations from inbound to outbound data flows.

Spring Cloud Stream supports the following reactive APIs:

  • Reactor
  • RxJava 1.x

In the future, it is intended to support a more generic model based on Reactive Streams.

The reactive programming model is also using the @StreamListener annotation for setting up reactive handlers. The differences are that:

  • the @StreamListener annotation must not specify an input or output, as they are provided as arguments and return values from the method;
  • the arguments of the method must be annotated with @Input and @Output indicating which input or output will the incoming and respectively outgoing data flows connect to;
  • the return value of the method, if any, will be annotated with @Output, indicating the input where data shall be sent.
[Note]Note

Reactive programming support requires Java 1.8.

[Note]Note

As of Spring Cloud Stream 1.1.1 and later (starting with release train Brooklyn.SR2), reactive programming support requires the use of Reactor 3.0.4.RELEASE and higher. +Earlier Reactor versions (including 3.0.1.RELEASE, 3.0.2.RELEASE and 3.0.3.RELEASE) are not supported. +spring-cloud-stream-reactive will transitively retrieve the proper version, but it is possible for the project structure to manage the version of the io.projectreactor:reactor-core to an earlier release, especially when using Maven. +This is the case for projects generated via Spring Initializr with Spring Boot 1.x, which will override the Reactor version to 2.0.8.RELEASE. +In such cases you must ensure that the proper version of the artifact is released. +This can be simply achieved by adding a direct dependency on io.projectreactor:reactor-core with a version of 3.0.4.RELEASE or later to your project.

[Note]Note

The use of term reactive is currently referring to the reactive APIs being used and not to the execution model being reactive (i.e. the bound endpoints are still using a 'push' rather than 'pull' model). While some backpressure support is provided by the use of Reactor, we do intend on the long run to support entirely reactive pipelines by the use of native reactive clients for the connected middleware.

Reactor-based handlers

A Reactor based handler can have the following argument types:

  • For arguments annotated with @Input, it supports the Reactor type Flux. +The parameterization of the inbound Flux follows the same rules as in the case of individual message handling: it can be the entire Message, a POJO which can be the Message payload, or a POJO which is the result of a transformation based on the Message content-type header. Multiple inputs are provided;
  • For arguments annotated with Output, it supports the type FluxSender which connects a Flux produced by the method with an output. Generally speaking, specifying outputs as arguments is only recommended when the method can have multiple outputs;

A Reactor based handler supports a return type of Flux, case in which it must be annotated with @Output. We recommend using the return value of the method when a single output flux is available.

Here is an example of a simple Reactor-based Processor.

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  @Output(Processor.OUTPUT)
+  public Flux<String> receive(@Input(Processor.INPUT) Flux<String> input) {
+    return input.map(s -> s.toUpperCase());
+  }
+}

The same processor using output arguments looks like this:

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  public void receive(@Input(Processor.INPUT) Flux<String> input,
+     @Output(Processor.OUTPUT) FluxSender output) {
+     output.send(input.map(s -> s.toUpperCase()));
+  }
+}

RxJava 1.x support

RxJava 1.x handlers follow the same rules as Reactor-based one, but will use Observable and ObservableSender arguments and return types.

So the first example above will become:

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  @Output(Processor.OUTPUT)
+  public Observable<String> receive(@Input(Processor.INPUT) Observable<String> input) {
+    return input.map(s -> s.toUpperCase());
+  }
+}

The second example above will become:

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  public void receive(@Input(Processor.INPUT) Observable<String> input,
+     @Output(Processor.OUTPUT) ObservableSender output) {
+     output.send(input.map(s -> s.toUpperCase()));
+  }
+}

Reactive Sources

Spring Cloud Stream reactive support also provides the ability for creating reactive sources through the StreamEmitter annotation. +Using StreamEmitter annotation, a regular source may be converted to a reactive one. +StreamEmitter is a method level annotation that marks a method to be an emitter to outputs declared via EnableBinding. +It is not allowed to use the Input annotation along with StreamEmitter, as the methods marked with this annotation are not listening from any input, rather generating to an output. +Following the same programming model used in StreamListener, StreamEmitter also allows flexible ways of using the Output annotation depending on whether the method has any arguments, return type etc.

Here are some examples of using StreamEmitter in various styles.

The following example will emit the "Hello World" message every millisecond and publish to a Flux. +In this case, the resulting messages in Flux will be sent to the output channel of the Source.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  @Output(Source.OUTPUT)
+  public Flux<String> emit() {
+    return Flux.intervalMillis(1)
+            .map(l -> "Hello World");
+  }
+}

Following is another flavor of the same sample as above. +Instead of returning a Flux, this method uses a FluxSender to programmatically send Flux from a source.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  @Output(Source.OUTPUT)
+  public void emit(FluxSender output) {
+    output.send(Flux.intervalMillis(1)
+            .map(l -> "Hello World"));
+  }
+}

Following is exactly same as the above snippet in functionality and style. +However, instead of using an explicit Output annotation at the method level, it is used as the method parameter level.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  public void emit(@Output(Source.OUTPUT) FluxSender output) {
+    output.send(Flux.intervalMillis(1)
+            .map(l -> "Hello World"));
+  }
+}

Here is yet another flavor of writing reacting sources using the Reactive Streams Publisher API and the support for it in the Spring Integration Java DSL. +The Publisher is still using Reactor Flux under the hood, but from an application perspective, that is transparent to the user and only needs Reactive Streams and Java DSL for Spring Integration.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  @Output(Source.OUTPUT)
+  @Bean
+  public Publisher<Message<String>> emit() {
+    return IntegrationFlows.from(() ->
+                new GenericMessage<>("Hello World"),
+        e -> e.poller(p -> p.fixedDelay(1)))
+        .toReactivePublisher();
+  }
+}

26.1.6 Aggregation

Spring Cloud Stream provides support for aggregating multiple applications together, connecting their input and output channels directly and avoiding the additional cost of exchanging messages via a broker. +As of version 1.0 of Spring Cloud Stream, aggregation is supported only for the following types of applications:

  • sources - applications with a single output channel named output, typically having a single binding of the type org.springframework.cloud.stream.messaging.Source
  • sinks - applications with a single input channel named input, typically having a single binding of the type org.springframework.cloud.stream.messaging.Sink
  • processors - applications with a single input channel named input and a single output channel named output, typically having a single binding of the type org.springframework.cloud.stream.messaging.Processor.

They can be aggregated together by creating a sequence of interconnected applications, in which the output channel of an element in the sequence is connected to the input channel of the next element, if it exists. +A sequence can start with either a source or a processor, it can contain an arbitrary number of processors and must end with either a processor or a sink.

Depending on the nature of the starting and ending element, the sequence may have one or more bindable channels, as follows:

  • if the sequence starts with a source and ends with a sink, all communication between the applications is direct and no channels will be bound
  • if the sequence starts with a processor, then its input channel will become the input channel of the aggregate and will be bound accordingly
  • if the sequence ends with a processor, then its output channel will become the output channel of the aggregate and will be bound accordingly

Aggregation is performed using the AggregateApplicationBuilder utility class, as in the following example. +Let’s consider a project in which we have source, processor and a sink, which may be defined in the project, or may be contained in one of the project’s dependencies.

[Note]Note

Each component (source, sink or processor) in an aggregate application must be provided in a separate package if the configuration classes use @SpringBootApplication. +This is required to avoid cross-talk between applications, due to the classpath scanning performed by @SpringBootApplication on the configuration classes inside the same package. +In the example below, it can be seen that the Source, Processor and Sink application classes are grouped in separate packages. +A possible alternative is to provide the source, sink or processor configuration in a separate @Configuration class, avoid the use of @SpringBootApplication/@ComponentScan and use those for aggregation.

package com.app.mysink;
+
+@SpringBootApplication
+@EnableBinding(Sink.class)
+public class SinkApplication {
+
+	private static Logger logger = LoggerFactory.getLogger(SinkApplication.class);
+
+	@ServiceActivator(inputChannel=Sink.INPUT)
+	public void loggerSink(Object payload) {
+		logger.info("Received: " + payload);
+	}
+}
package com.app.myprocessor;
+
+// Imports omitted
+
+@SpringBootApplication
+@EnableBinding(Processor.class)
+public class ProcessorApplication {
+
+	@Transformer
+	public String loggerSink(String payload) {
+		return payload.toUpperCase();
+	}
+}
package com.app.mysource;
+
+// Imports omitted
+
+@SpringBootApplication
+@EnableBinding(Source.class)
+public class SourceApplication {
+
+	@InboundChannelAdapter(value = Source.OUTPUT)
+	public String timerMessageSource() {
+		return new SimpleDateFormat().format(new Date());
+	}
+}

Each configuration can be used for running a separate component, but in this case they can be aggregated together as follows:

package com.app;
+
+// Imports omitted
+
+@SpringBootApplication
+public class SampleAggregateApplication {
+
+	public static void main(String[] args) {
+		new AggregateApplicationBuilder()
+			.from(SourceApplication.class).args("--fixedDelay=5000")
+			.via(ProcessorApplication.class)
+			.to(SinkApplication.class).args("--debug=true").run(args);
+	}
+}

The starting component of the sequence is provided as argument to the from() method. +The ending component of the sequence is provided as argument to the to() method. +Intermediate processors are provided as argument to the via() method. +Multiple processors of the same type can be chained together (e.g. for pipelining transformations with different configurations). +For each component, the builder can provide runtime arguments for Spring Boot configuration.

Configuring aggregate application

Spring Cloud Stream supports passing properties for the individual applications inside the aggregate application using 'namespace' as prefix.

The namespace can be set for applications as follows:

@SpringBootApplication
+public class SampleAggregateApplication {
+
+	public static void main(String[] args) {
+		new AggregateApplicationBuilder()
+			.from(SourceApplication.class).namespace("source").args("--fixedDelay=5000")
+			.via(ProcessorApplication.class).namespace("processor1")
+			.to(SinkApplication.class).namespace("sink").args("--debug=true").run(args);
+	}
+}

Once the 'namespace' is set for the individual applications, the application properties with the namespace as prefix can be passed to the aggregate application using any supported property source (commandline, environment properties etc.,)

For instance, to override the default fixedDelay and debug properties of 'source' and 'sink' applications:

java -jar target/MyAggregateApplication-0.0.1-SNAPSHOT.jar --source.fixedDelay=10000 --sink.debug=false

Configuring binding service properties for non self contained aggregate application

The non self-contained aggregate application is bound to external broker via either or both the inbound/outbound components (typically, message channels) of the aggregate application while the applications inside the aggregate application are directly bound. +For example: a source application’s output and a processor application’s input are directly bound while the processor’s output channel is bound to an external destination at the broker. +When passing the binding service properties for non-self contained aggregate application, it is required to pass the binding service properties to the aggregate application instead of setting them as 'args' to individual child application. +For instance,

@SpringBootApplication
+public class SampleAggregateApplication {
+
+	public static void main(String[] args) {
+		new AggregateApplicationBuilder()
+			.from(SourceApplication.class).namespace("source").args("--fixedDelay=5000")
+			.via(ProcessorApplication.class).namespace("processor1").args("--debug=true").run(args);
+	}
+}

The binding properties like --spring.cloud.stream.bindings.output.destination=processor-output need to be specified as one of the external configuration properties (cmdline arg etc.,).

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25. Main Concepts Home 27. Binders
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9. Push Notifications and Spring Cloud Bus
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9. Push Notifications and Spring Cloud Bus

Many source code repository providers (like Github, Gitlab or Bitbucket +for instance) will notify you of changes in a repository through a +webhook. You can configure the webhook via the provider’s user +interface as a URL and a set of events in which you are +interested. For instance +Github +will POST to the webhook with a JSON body containing a list of +commits, and a header "X-Github-Event" equal to "push". If you add a +dependency on the spring-cloud-config-monitor library and activate +the Spring Cloud Bus in your Config Server, then a "/monitor" endpoint +is enabled.

When the webhook is activated the Config Server will send a +RefreshRemoteApplicationEvent targeted at the applications it thinks +might have changed. The change detection can be strategized, but by +default it just looks for changes in files that match the application +name (e.g. "foo.properties" is targeted at the "foo" application, and +"application.properties" is targeted at all applications). The strategy +if you want to override the behaviour is PropertyPathNotificationExtractor +which accepts the request headers and body as parameters and returns a list +of file paths that changed.

The default configuration works out of the box with Github, Gitlab or +Bitbucket. In addition to the JSON notifications from Github, Gitlab +or Bitbucket you can trigger a change notification by POSTing to +"/monitor" with a form-encoded body parameters path={name}. This will +broadcast to applications matching the "{name}" pattern (can contain +wildcards).

[Note]Note

the RefreshRemoteApplicationEvent will only be transmitted if +the spring-cloud-bus is activated in the Config Server and in the +client application.

[Note]Note

the default configuration also detects filesystem changes in +local git repositories (the webhook is not used in that case but as +soon as you edit a config file a refresh will be broadcast).

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8. Embedding the Config Server Home 10. Spring Cloud Config Client
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4. Quick Start
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4. Quick Start

Start the server:

$ cd spring-cloud-config-server
+$ ../mvnw spring-boot:run

The server is a Spring Boot application so you can run it from your +IDE instead if you prefer (the main class is +ConfigServerApplication). Then try out a client:

$ curl localhost:8888/foo/development
+{"name":"foo","label":"master","propertySources":[
+  {"name":"https://github.com/scratches/config-repo/foo-development.properties","source":{"bar":"spam"}},
+  {"name":"https://github.com/scratches/config-repo/foo.properties","source":{"foo":"bar"}}
+]}

The default strategy for locating property sources is to clone a git +repository (at spring.cloud.config.server.git.uri) and use it to +initialize a mini SpringApplication. The mini-application’s +Environment is used to enumerate property sources and publish them +via a JSON endpoint.

The HTTP service has resources in the form:

/{application}/{profile}[/{label}]
+/{application}-{profile}.yml
+/{label}/{application}-{profile}.yml
+/{application}-{profile}.properties
+/{label}/{application}-{profile}.properties

where the "application" is injected as the spring.config.name in the +SpringApplication (i.e. what is normally "application" in a regular +Spring Boot app), "profile" is an active profile (or comma-separated +list of properties), and "label" is an optional git label (defaults to +"master".)

Spring Cloud Config Server pulls configuration for remote clients +from a git repository (which must be provided):

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo

4.1 Client Side Usage

To use these features in an application, just build it as a Spring +Boot application that depends on spring-cloud-config-client (e.g. see +the test cases for the config-client, or the sample app). The most +convenient way to add the dependency is via a Spring Boot starter +org.springframework.cloud:spring-cloud-starter-config. There is also a +parent pom and BOM (spring-cloud-starter-parent) for Maven users and a +Spring IO version management properties file for Gradle and Spring CLI +users. Example Maven configuration:

pom.xml.  +

   <parent>
+       <groupId>org.springframework.boot</groupId>
+       <artifactId>spring-boot-starter-parent</artifactId>
+       <version>1.5.10.RELEASE</version>
+       <relativePath /> <!-- lookup parent from repository -->
+   </parent>
+
+<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>Edgware.SR2</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>
+
+<dependencies>
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-starter-config</artifactId>
+	</dependency>
+	<dependency>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-test</artifactId>
+		<scope>test</scope>
+	</dependency>
+</dependencies>
+
+<build>
+	<plugins>
+           <plugin>
+               <groupId>org.springframework.boot</groupId>
+               <artifactId>spring-boot-maven-plugin</artifactId>
+           </plugin>
+	</plugins>
+</build>
+
+   <!-- repositories also needed for snapshots and milestones -->

+

Then you can create a standard Spring Boot application, like this simple HTTP server:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello World!";
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}

When it runs it will pick up the external configuration from the +default local config server on port 8888 if it is running. To modify +the startup behaviour you can change the location of the config server +using bootstrap.properties (like application.properties but for +the bootstrap phase of an application context), e.g.

spring.cloud.config.uri: http://myconfigserver.com

The bootstrap properties will show up in the /env endpoint as a +high-priority property source, e.g.

$ curl localhost:8080/env
+{
+  "profiles":[],
+  "configService:https://github.com/spring-cloud-samples/config-repo/bar.properties":{"foo":"bar"},
+  "servletContextInitParams":{},
+  "systemProperties":{...},
+  ...
+}

(a property source called "configService:<URL of remote +repository>/<file name>" contains the property "foo" with value +"bar" and is highest priority).

[Note]Note

the URL in the property source name is the git repository not +the config server URL.

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Part II. Spring Cloud Config Home 5. Spring Cloud Config Server
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39. Quick Start
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39. Quick Start

Spring Cloud Bus works by adding Spring Boot autconfiguration if it detects itself on the classpath. All you need to do to enable the bus is to add spring-cloud-starter-bus-amqp or spring-cloud-starter-bus-kafka to your dependency management and Spring Cloud takes care of the rest. Make sure the broker (RabbitMQ or Kafka) is available and configured: running on localhost you shouldn’t have to do anything, but if you are running remotely use Spring Cloud Connectors, or Spring Boot conventions to define the broker credentials, e.g. for Rabbit

application.yml.  +

spring:
+  rabbitmq:
+    host: mybroker.com
+    port: 5672
+    username: user
+    password: secret

+

The bus currently supports sending messages to all nodes listening or all nodes for a particular service (as defined by Eureka). More selector criteria may be added in the future (ie. only service X nodes in data center Y, etc…​). There are also some http endpoints under the /bus/* actuator namespace. There are currently two implemented. The first, /bus/env, sends key/value pairs to update each node’s Spring Environment. The second, /bus/refresh, will reload each application’s configuration, just as if they had all been pinged on their /refresh endpoint.

[Note]Note

The Bus starters cover Rabbit and Kafka, because those are the two most common implementations, but Spring Cloud Stream is quite flexible and binder will work combined with spring-cloud-bus.

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Part VI. Spring Cloud Bus Home 40. Addressing an Instance
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97. Quick Start
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97. Quick Start

Prerequisites

To get started with Vault and this guide you need a +*NIX-like operating systems that provides:

  • wget, openssl and unzip
  • at least Java 7 and a properly configured JAVA_HOME environment variable

Install Vault

$ src/test/bash/install_vault.sh

Create SSL certificates for Vault

$ src/test/bash/create_certificates.sh
[Note]Note

create_certificates.sh creates certificates in work/ca and a JKS truststore work/keystore.jks. If you want to run Spring Cloud Vault using this quickstart guide you need to configure the truststore the spring.cloud.vault.ssl.trust-store property to file:work/keystore.jks.

Start Vault server

$ src/test/bash/local_run_vault.sh

Vault is started listening on 0.0.0.0:8200 using the inmem storage and +https. +Vault is sealed and not initialized when starting up.

[Note]Note

If you want to run tests, leave Vault uninitialized. The tests will +initialize Vault and create a root token 00000000-0000-0000-0000-000000000000.

If you want to use Vault for your application or give it a try then you need to initialize it first.

$ export VAULT_ADDR="https://localhost:8200"
+$ export VAULT_SKIP_VERIFY=true # Don't do this for production
+$ vault init

You should see something like:

Key 1: 7149c6a2e16b8833f6eb1e76df03e47f6113a3288b3093faf5033d44f0e70fe701
+Key 2: 901c534c7988c18c20435a85213c683bdcf0efcd82e38e2893779f152978c18c02
+Key 3: 03ff3948575b1165a20c20ee7c3e6edf04f4cdbe0e82dbff5be49c63f98bc03a03
+Key 4: 216ae5cc3ddaf93ceb8e1d15bb9fc3176653f5b738f5f3d1ee00cd7dccbe926e04
+Key 5: b2898fc8130929d569c1677ee69dc5f3be57d7c4b494a6062693ce0b1c4d93d805
+Initial Root Token: 19aefa97-cccc-bbbb-aaaa-225940e63d76
+
+Vault initialized with 5 keys and a key threshold of 3. Please
+securely distribute the above keys. When the Vault is re-sealed,
+restarted, or stopped, you must provide at least 3 of these keys
+to unseal it again.
+
+Vault does not store the master key. Without at least 3 keys,
+your Vault will remain permanently sealed.

Vault will initialize and return a set of unsealing keys and the root token. +Pick 3 keys and unseal Vault. Store the Vault token in the VAULT_TOKEN + environment variable.

$ vault unseal (Key 1)
+$ vault unseal (Key 2)
+$ vault unseal (Key 3)
+$ export VAULT_TOKEN=(Root token)
+# Required to run Spring Cloud Vault tests after manual initialization
+$ vault token-create -id="00000000-0000-0000-0000-000000000000" -policy="root"

Spring Cloud Vault accesses different resources. By default, the secret +backend is enabled which accesses secret config settings via JSON endpoints.

The HTTP service has resources in the form:

/secret/{application}/{profile}
+/secret/{application}
+/secret/{defaultContext}/{profile}
+/secret/{defaultContext}

where the "application" is injected as the spring.application.name in the +SpringApplication (i.e. what is normally "application" in a regular +Spring Boot app), "profile" is an active profile (or comma-separated +list of properties). Properties retrieved from Vault will be used "as-is" +without further prefixing of the property names.

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Part XIV. Spring Cloud Vault Home 98. Client Side Usage
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79. Quickstart
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79. Quickstart

79.1 OAuth2 Single Sign On

Here’s a Spring Cloud "Hello World" app with HTTP Basic +authentication and a single user account:

app.groovy.  +

@Grab('spring-boot-starter-security')
+@Controller
+class Application {
+
+  @RequestMapping('/')
+  String home() {
+    'Hello World'
+  }
+
+}

+

You can run it with spring run app.groovy and watch the logs for the password (username is "user"). So far this is just the default for a Spring Boot app.

Here’s a Spring Cloud app with OAuth2 SSO:

app.groovy.  +

@Controller
+@EnableOAuth2Sso
+class Application {
+
+  @RequestMapping('/')
+  String home() {
+    'Hello World'
+  }
+
+}

+

Spot the difference? This app will actually behave exactly the same as +the previous one, because it doesn’t know it’s OAuth2 credentals +yet.

You can register an app in github quite easily, so try that if you +want a production app on your own domain. If you are happy to test on +localhost:8080, then set up these properties in your application +configuration:

application.yml.  +

security:
+  oauth2:
+    client:
+      clientId: bd1c0a783ccdd1c9b9e4
+      clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1
+      accessTokenUri: https://github.com/login/oauth/access_token
+      userAuthorizationUri: https://github.com/login/oauth/authorize
+      clientAuthenticationScheme: form
+    resource:
+      userInfoUri: https://api.github.com/user
+      preferTokenInfo: false

+

run the app above and it will redirect to github for authorization. If +you are already signed into github you won’t even notice that it has +authenticated. These credentials will only work if your app is +running on port 8080.

To limit the scope that the client asks for when it obtains an access token +you can set security.oauth2.client.scope (comma separated or an array in YAML). By +default the scope is empty and it is up to to Authorization Server to +decide what the defaults should be, usually depending on the settings in +the client registration that it holds.

[Note]Note

The examples above are all Groovy scripts. If you want to write the +same code in Java (or Groovy) you need to add Spring Security OAuth2 +to the classpath (e.g. see the +sample here).

79.2 OAuth2 Protected Resource

You want to protect an API resource with an OAuth2 token? Here’s a +simple example (paired with the client above):

app.groovy.  +

@Grab('spring-cloud-starter-security')
+@RestController
+@EnableResourceServer
+class Application {
+
+  @RequestMapping('/')
+  def home() {
+    [message: 'Hello World']
+  }
+
+}

+

and

application.yml.  +

security:
+  oauth2:
+    resource:
+      userInfoUri: https://api.github.com/user
+      preferTokenInfo: false

+

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Part XI. Spring Cloud Security Home 80. More Detail
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38. RabbitMQ Binder
Prev Part V. Binder Implementations Next

38. RabbitMQ Binder

38.1 Usage

For using the RabbitMQ binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-rabbit</artifactId>
+</dependency>

Alternatively, you can also use the Spring Cloud Stream RabbitMQ Starter.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-starter-stream-rabbit</artifactId>
+</dependency>

38.2 RabbitMQ Binder Overview

A simplified diagram of how the RabbitMQ binder operates can be seen below.

Figure 38.1. RabbitMQ Binder

rabbit binder

The RabbitMQ Binder implementation maps each destination to a TopicExchange. +For each consumer group, a Queue will be bound to that TopicExchange. +Each consumer instance have a corresponding RabbitMQ Consumer instance for its group’s Queue. +For partitioned producers/consumers the queues are suffixed with the partition index and use the partition index as routing key.

Using the autoBindDlq option, you can optionally configure the binder to create and configure dead-letter queues (DLQs) (and a dead-letter exchange DLX). +The dead letter queue has the name of the destination, appended with .dlq. +If retry is enabled (maxAttempts > 1) failed messages will be delivered to the DLQ. +If retry is disabled (maxAttempts = 1), you should set requeueRejected to false (default) so that a failed message will be routed to the DLQ, instead of being requeued. +In addition, republishToDlq causes the binder to publish a failed message to the DLQ (instead of rejecting it); this enables additional information to be added to the message in headers, such as the stack trace in the x-exception-stacktrace header. +This option does not need retry enabled; you can republish a failed message after just one attempt. +Starting with version 1.2, you can configure the delivery mode of republished messages; see property republishDeliveryMode.

[Important]Important

Setting requeueRejected to true will cause the message to be requeued and redelivered continually, which is likely not what you want unless the failure issue is transient. +In general, it’s better to enable retry within the binder by setting maxAttempts to greater than one, or set republishToDlq to true.

See Section 38.3.1, “RabbitMQ Binder Properties” for more information about these properties.

The framework does not provide any standard mechanism to consume dead-letter messages (or to re-route them back to the primary queue). +Some options are described in Section 38.6, “Dead-Letter Queue Processing”.

[Note]Note

When multiple RabbitMQ binders are used in a Spring Cloud Stream application, it is important to disable 'RabbitAutoConfiguration' to avoid the same configuration from RabbitAutoConfiguration being applied to the two binders.

Starting with version 1.3, the RabbitMessageChannelBinder creates an internal ConnectionFactory copy for the non-transactional producers to avoid dead locks on consumers when shared, cached connections are blocked because of Memory Alarm on Broker.

38.3 Configuration Options

This section contains settings specific to the RabbitMQ Binder and bound channels.

For general binding configuration options and properties, +please refer to the Spring Cloud Stream core documentation.

38.3.1 RabbitMQ Binder Properties

By default, the RabbitMQ binder uses Spring Boot’s ConnectionFactory, and it therefore supports all Spring Boot configuration options for RabbitMQ. +(For reference, consult the Spring Boot documentation.) +RabbitMQ configuration options use the spring.rabbitmq prefix.

In addition to Spring Boot options, the RabbitMQ binder supports the following properties:

spring.cloud.stream.rabbit.binder.adminAddresses

A comma-separated list of RabbitMQ management plugin URLs. +Only used when nodes contains more than one entry. +Each entry in this list must have a corresponding entry in spring.rabbitmq.addresses. +Only needed if you are using a RabbitMQ cluster and wish to consume from the node that hosts the queue. +See Queue Affinity and the LocalizedQueueConnectionFactory for more information.

Default: empty.

spring.cloud.stream.rabbit.binder.nodes

A comma-separated list of RabbitMQ node names. +When more than one entry, used to locate the server address where a queue is located. +Each entry in this list must have a corresponding entry in spring.rabbitmq.addresses. +Only needed if you are using a RabbitMQ cluster and wish to consume from the node that hosts the queue. +See Queue Affinity and the LocalizedQueueConnectionFactory for more information.

Default: empty.

spring.cloud.stream.rabbit.binder.compressionLevel

Compression level for compressed bindings. +See java.util.zip.Deflater.

Default: 1 (BEST_LEVEL).

38.3.2 RabbitMQ Consumer Properties

The following properties are available for Rabbit consumers only and +must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.consumer..

acknowledgeMode

The acknowledge mode.

Default: AUTO.

autoBindDlq

Whether to automatically declare the DLQ and bind it to the binder DLX.

Default: false.

bindingRoutingKey

The routing key with which to bind the queue to the exchange (if bindQueue is true). +for partitioned destinations -<instanceIndex> will be appended.

Default: #.

bindQueue

Whether to bind the queue to the destination exchange; set to false if you have set up your own infrastructure and have previously created/bound the queue.

Default: true.

deadLetterQueueName

name of the DLQ

Default: prefix+destination.dlq

deadLetterExchange

a DLX to assign to the queue; if autoBindDlq is true

Default: 'prefix+DLX'

deadLetterRoutingKey

a dead letter routing key to assign to the queue; if autoBindDlq is true

Default: destination

declareExchange

Whether to declare the exchange for the destination.

Default: true.

delayedExchange

Whether to declare the exchange as a Delayed Message Exchange - requires the delayed message exchange plugin on the broker. +The x-delayed-type argument is set to the exchangeType.

Default: false.

dlqDeadLetterExchange

if a DLQ is declared, a DLX to assign to that queue

Default: none

dlqDeadLetterRoutingKey

if a DLQ is declared, a dead letter routing key to assign to that queue; default none

Default: none

dlqExpires

how long before an unused dead letter queue is deleted (ms)

Default: no expiration

dlqLazy

Declare the dead letter queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue.

Default: false.

dlqMaxLength

maximum number of messages in the dead letter queue

Default: no limit

dlqMaxLengthBytes

maximum number of total bytes in the dead letter queue from all messages

Default: no limit

dlqMaxPriority

maximum priority of messages in the dead letter queue (0-255)

Default: none

dlqTtl

default time to live to apply to the dead letter queue when declared (ms)

Default: no limit

durableSubscription

Whether subscription should be durable. +Only effective if group is also set.

Default: true.

exchangeAutoDelete

If declareExchange is true, whether the exchange should be auto-delete (removed after the last queue is removed).

Default: true.

exchangeDurable

If declareExchange is true, whether the exchange should be durable (survives broker restart).

Default: true.

exchangeType

The exchange type; direct, fanout or topic for non-partitioned destinations; direct or topic for partitioned destinations.

Default: topic.

exclusive

Create an exclusive consumer; concurrency should be 1 when this is true; often used when strict ordering is required but enabling a hot standby instance to take over after a failure. +See recoveryInterval, which controls how often a standby instance will attempt to consume.

Default: false.

expires

how long before an unused queue is deleted (ms)

Default: no expiration

failedDeclarationRetryInterval

The interval (ms) between attempts to consume from a queue if it is missing.

Default: 5000

headerPatterns

Patterns for headers to be mapped from inbound messages.

Default: ['*'] (all headers).

lazy

Declare the queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue.

Default: false.

maxConcurrency

the maximum number of consumers

Default: 1.

maxLength

maximum number of messages in the queue

Default: no limit

maxLengthBytes

maximum number of total bytes in the queue from all messages

Default: no limit

maxPriority
maximum priority of messages in the queue (0-255)
Default
none
missingQueuesFatal
If the queue cannot be found, treat the condition as fatal and stop the listener container. +Defaults to false so that the container keeps trying to consume from the queue, for example when using a cluster and the node hosting a non HA queue is down.
Default
false
prefetch

Prefetch count.

Default: 1.

prefix

A prefix to be added to the name of the destination and queues.

Default: "".

queueDeclarationRetries
The number of times to retry consuming from a queue if it is missing. +Only relevant if missingQueuesFatal is true; otherwise the container keeps retrying indefinitely.
Default
3
queueNameGroupOnly

When true, consume from a queue with a name equal to the group; otherwise the queue name is destination.group. +This is useful, for example, when using Spring Cloud Stream to consume from an existing RabbitMQ queue.

Default: false.

recoveryInterval

The interval between connection recovery attempts, in milliseconds.

Default: 5000.

requeueRejected

Whether delivery failures should be requeued when retry is disabled or republishToDlq is false.

Default: false.

republishDeliveryMode

When republishToDlq is true, specify the delivery mode of the republished message.

Default: DeliveryMode.PERSISTENT

republishToDlq

By default, messages which fail after retries are exhausted are rejected. +If a dead-letter queue (DLQ) is configured, RabbitMQ will route the failed message (unchanged) to the DLQ. +If set to true, the binder will republish failed messages to the DLQ with additional headers, including the exception message and stack trace from the cause of the final failure.

Default: false

transacted

Whether to use transacted channels.

Default: false.

ttl

default time to live to apply to the queue when declared (ms)

Default: no limit

txSize

The number of deliveries between acks.

Default: 1.

38.3.3 Rabbit Producer Properties

The following properties are available for Rabbit producers only and +must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.producer..

autoBindDlq

Whether to automatically declare the DLQ and bind it to the binder DLX.

Default: false.

batchingEnabled

Whether to enable message batching by producers.

Default: false.

batchSize

The number of messages to buffer when batching is enabled.

Default: 100.

batchBufferLimit
Default: 10000.
batchTimeout
Default: 5000.
bindingRoutingKey

The routing key with which to bind the queue to the exchange (if bindQueue is true). +Only applies to non-partitioned destinations. +Only applies if requiredGroups are provided and then only to those groups.

Default: #.

bindQueue

Whether to bind the queue to the destination exchange; set to false if you have set up your own infrastructure and have previously created/bound the queue. +Only applies if requiredGroups are provided and then only to those groups.

Default: true.

compress

Whether data should be compressed when sent.

Default: false.

deadLetterQueueName

name of the DLQ +Only applies if requiredGroups are provided and then only to those groups.

Default: prefix+destination.dlq

deadLetterExchange

a DLX to assign to the queue; if autoBindDlq is true +Only applies if requiredGroups are provided and then only to those groups.

Default: 'prefix+DLX'

deadLetterRoutingKey

a dead letter routing key to assign to the queue; if autoBindDlq is true +Only applies if requiredGroups are provided and then only to those groups.

Default: destination

declareExchange

Whether to declare the exchange for the destination.

Default: true.

delay

A SpEL expression to evaluate the delay to apply to the message (x-delay header) - has no effect if the exchange is not a delayed message exchange.

Default: No x-delay header is set.

delayedExchange

Whether to declare the exchange as a Delayed Message Exchange - requires the delayed message exchange plugin on the broker. +The x-delayed-type argument is set to the exchangeType.

Default: false.

deliveryMode

Delivery mode.

Default: PERSISTENT.

dlqDeadLetterExchange

if a DLQ is declared, a DLX to assign to that queue +Only applies if requiredGroups are provided and then only to those groups.

Default: none

dlqDeadLetterRoutingKey

if a DLQ is declared, a dead letter routing key to assign to that queue; default none +Only applies if requiredGroups are provided and then only to those groups.

Default: none

dlqExpires

how long before an unused dead letter queue is deleted (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no expiration

dlqLazy
Declare the dead letter queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Only applies if requiredGroups are provided and then only to those groups.
dlqMaxLength

maximum number of messages in the dead letter queue +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

dlqMaxLengthBytes

maximum number of total bytes in the dead letter queue from all messages +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

dlqMaxPriority

maximum priority of messages in the dead letter queue (0-255) +Only applies if requiredGroups are provided and then only to those groups.

Default: none

dlqTtl

default time to live to apply to the dead letter queue when declared (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

exchangeAutoDelete

If declareExchange is true, whether the exchange should be auto-delete (removed after the last queue is removed).

Default: true.

exchangeDurable

If declareExchange is true, whether the exchange should be durable (survives broker restart).

Default: true.

exchangeType

The exchange type; direct, fanout or topic for non-partitioned destinations; direct or topic for partitioned destinations.

Default: topic.

expires

how long before an unused queue is deleted (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no expiration

headerPatterns

Patterns for headers to be mapped to outbound messages.

Default: ['*'] (all headers).

lazy

Declare the queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Only applies if requiredGroups are provided and then only to those groups.

Default: false.

maxLength

maximum number of messages in the queue +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

maxLengthBytes

maximum number of total bytes in the queue from all messages +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

maxPriority
maximum priority of messages in the queue (0-255) +Only applies if requiredGroups are provided and then only to those groups.
Default
none
prefix

A prefix to be added to the name of the destination exchange.

Default: "".

queueNameGroupOnly

When true, consume from a queue with a name equal to the group; otherwise the queue name is destination.group. +This is useful, for example, when using Spring Cloud Stream to consume from an existing RabbitMQ queue. +Only applies if requiredGroups are provided and then only to those groups.

Default: false.

routingKeyExpression

A SpEL expression to determine the routing key to use when publishing messages. +For a fixed routing key, use a literal expression, e.g. routingKeyExpression='my.routingKey' in a properties file, or routingKeyExpression: '''my.routingKey''' in a YAML file.

Default: destination or destination-<partition> for partitioned destinations.

transacted

Whether to use transacted channels.

Default: false.

ttl

default time to live to apply to the queue when declared (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

[Note]Note

In the case of RabbitMQ, content type headers can be set by external applications. +Spring Cloud Stream supports them as part of an extended internal protocol used for any type of transport (including transports, such as Kafka, that do not normally support headers).

38.4 Retry With the RabbitMQ Binder

38.4.1 Overview

When retry is enabled within the binder, the listener container thread is suspended for any back off periods that are configured. +This might be important when strict ordering is required with a single consumer but for other use cases it prevents other messages from being processed on that thread. +An alternative to using binder retry is to set up dead lettering with time to live on the dead-letter queue (DLQ), as well as dead-letter configuration on the DLQ itself. +See Section 38.3.1, “RabbitMQ Binder Properties” for more information about the properties discussed here. +Example configuration to enable this feature:

  • Set autoBindDlq to true - the binder will create a DLQ; you can optionally specify a name in deadLetterQueueName
  • Set dlqTtl to the back off time you want to wait between redeliveries
  • Set the dlqDeadLetterExchange to the default exchange - expired messages from the DLQ will be routed to the original queue since the default deadLetterRoutingKey is the queue name (destination.group)

To force a message to be dead-lettered, either throw an AmqpRejectAndDontRequeueException, or set requeueRejected to true and throw any exception.

The loop will continue without end, which is fine for transient problems but you may want to give up after some number of attempts. +Fortunately, RabbitMQ provides the x-death header which allows you to determine how many cycles have occurred.

To acknowledge a message after giving up, throw an ImmediateAcknowledgeAmqpException.

38.4.2 Putting it All Together

---
+spring.cloud.stream.bindings.input.destination=myDestination
+spring.cloud.stream.bindings.input.group=consumerGroup
+#disable binder retries
+spring.cloud.stream.bindings.input.consumer.max-attempts=1
+#dlx/dlq setup
+spring.cloud.stream.rabbit.bindings.input.consumer.auto-bind-dlq=true
+spring.cloud.stream.rabbit.bindings.input.consumer.dlq-ttl=5000
+spring.cloud.stream.rabbit.bindings.input.consumer.dlq-dead-letter-exchange=
+---

This configuration creates an exchange myDestination with queue myDestination.consumerGroup bound to a topic exchange with a wildcard routing key #. +It creates a DLQ bound to a direct exchange DLX with routing key myDestination.consumerGroup. +When messages are rejected, they are routed to the DLQ. +After 5 seconds, the message expires and is routed to the original queue using the queue name as the routing key.

Spring Boot application.  +

@SpringBootApplication
+@EnableBinding(Sink.class)
+public class XDeathApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(XDeathApplication.class, args);
+    }
+
+    @StreamListener(Sink.INPUT)
+    public void listen(String in, @Header(name = "x-death", required = false) Map<?,?> death) {
+        if (death != null && death.get("count").equals(3L)) {
+            // giving up - don't send to DLX
+            throw new ImmediateAcknowledgeAmqpException("Failed after 4 attempts");
+        }
+        throw new AmqpRejectAndDontRequeueException("failed");
+    }
+
+}

+

Notice that the count property in the x-death header is a Long.

38.5 Error Channels

Starting with version 1.3, the binder unconditionally sends exceptions to an error channel for each consumer destination, and can be configured to send async producer send failures to an error channel too. +See the section called “Message Channel Binders and Error Channels” for more information.

With rabbitmq, there are two types of send failures:

The latter is rare; quoting the RabbitMQ documentation "[A nack] will only be delivered if an internal error occurs in the Erlang process responsible for a queue.".

As well as enabling producer error channels as described in the section called “Message Channel Binders and Error Channels”, the RabbitMQ binder will only send messages to the channels if the connection factory is appropriately configured:

  • ccf.setPublisherConfirms(true);
  • ccf.setPublisherReturns(true);

When using spring boot configuration for the connection factory, set properties:

  • spring.rabbitmq.publisher-confirms
  • spring.rabbitmq.publisher-returns

The payload of the ErrorMessage for a returned message is a ReturnedAmqpMessageException with properties:

  • failedMessage - the spring-messaging Message<?> that failed to be sent.
  • amqpMessage - the raw spring-amqp Message
  • replyCode - an integer value indicating the reason for the failure (e.g. 312 - No route)
  • replyText - a text value indicating the reason for the failure e.g. NO_ROUTE.
  • exchange - the exchange to which the message was published.
  • routingKey - the routing key used when the message was published.

For negatively acknowledged confirms, the payload is a NackedAmqpMessageException with properties:

  • failedMessage - the spring-messaging Message<?> that failed to be sent.
  • nackReason - a reason (if available; you may need to examine the broker logs for more information).

There is no automatic handling of these exceptions (such as sending to a Dead-Letter queue); you can consume these exceptions with your own Spring Integration flow.

38.6 Dead-Letter Queue Processing

Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them. +If the reason for the dead-lettering is transient, you may wish to route the messages back to the original queue. +However, if the problem is a permanent issue, that could cause an infinite loop. +The following spring-boot application is an example of how to route those messages back to the original queue, but moves them to a third "parking lot" queue after three attempts. +The second example utilizes the RabbitMQ Delayed Message Exchange to introduce a delay to the requeued message. +In this example, the delay increases for each attempt. +These examples use a @RabbitListener to receive messages from the DLQ, you could also use RabbitTemplate.receive() in a batch process.

The examples assume the original destination is so8400in and the consumer group is so8400.

38.6.1 Non-Partitioned Destinations

The first two examples are when the destination is not partitioned.

@SpringBootApplication
+public class ReRouteDlqApplication {
+
+    private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+    private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+    private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+    private static final String X_RETRIES_HEADER = "x-retries";
+
+    public static void main(String[] args) throws Exception {
+        ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+        System.out.println("Hit enter to terminate");
+        System.in.read();
+        context.close();
+    }
+
+    @Autowired
+    private RabbitTemplate rabbitTemplate;
+
+    @RabbitListener(queues = DLQ)
+    public void rePublish(Message failedMessage) {
+        Integer retriesHeader = (Integer) failedMessage.getMessageProperties().getHeaders().get(X_RETRIES_HEADER);
+        if (retriesHeader == null) {
+            retriesHeader = Integer.valueOf(0);
+        }
+        if (retriesHeader < 3) {
+            failedMessage.getMessageProperties().getHeaders().put(X_RETRIES_HEADER, retriesHeader + 1);
+            this.rabbitTemplate.send(ORIGINAL_QUEUE, failedMessage);
+        }
+        else {
+            this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+        }
+    }
+
+    @Bean
+    public Queue parkingLot() {
+        return new Queue(PARKING_LOT);
+    }
+
+}
@SpringBootApplication
+public class ReRouteDlqApplication {
+
+    private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+    private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+    private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+    private static final String X_RETRIES_HEADER = "x-retries";
+
+    private static final String DELAY_EXCHANGE = "dlqReRouter";
+
+    public static void main(String[] args) throws Exception {
+        ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+        System.out.println("Hit enter to terminate");
+        System.in.read();
+        context.close();
+    }
+
+    @Autowired
+    private RabbitTemplate rabbitTemplate;
+
+    @RabbitListener(queues = DLQ)
+    public void rePublish(Message failedMessage) {
+        Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
+        Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
+        if (retriesHeader == null) {
+            retriesHeader = Integer.valueOf(0);
+        }
+        if (retriesHeader < 3) {
+            headers.put(X_RETRIES_HEADER, retriesHeader + 1);
+            headers.put("x-delay", 5000 * retriesHeader);
+            this.rabbitTemplate.send(DELAY_EXCHANGE, ORIGINAL_QUEUE, failedMessage);
+        }
+        else {
+            this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+        }
+    }
+
+    @Bean
+    public DirectExchange delayExchange() {
+        DirectExchange exchange = new DirectExchange(DELAY_EXCHANGE);
+        exchange.setDelayed(true);
+        return exchange;
+    }
+
+    @Bean
+    public Binding bindOriginalToDelay() {
+        return BindingBuilder.bind(new Queue(ORIGINAL_QUEUE)).to(delayExchange()).with(ORIGINAL_QUEUE);
+    }
+
+    @Bean
+    public Queue parkingLot() {
+        return new Queue(PARKING_LOT);
+    }
+
+}

38.6.2 Partitioned Destinations

With partitioned destinations, there is one DLQ for all partitions and we determine the original queue from the headers.

republishToDlq=false

When republishToDlq is false, RabbitMQ publishes the message to the DLX/DLQ with an x-death header containing information about the original destination.

@SpringBootApplication
+public class ReRouteDlqApplication {
+
+	private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+	private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+	private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+	private static final String X_DEATH_HEADER = "x-death";
+
+	private static final String X_RETRIES_HEADER = "x-retries";
+
+	public static void main(String[] args) throws Exception {
+		ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+		System.out.println("Hit enter to terminate");
+		System.in.read();
+		context.close();
+	}
+
+	@Autowired
+	private RabbitTemplate rabbitTemplate;
+
+	@SuppressWarnings("unchecked")
+	@RabbitListener(queues = DLQ)
+	public void rePublish(Message failedMessage) {
+		Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
+		Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
+		if (retriesHeader == null) {
+			retriesHeader = Integer.valueOf(0);
+		}
+		if (retriesHeader < 3) {
+			headers.put(X_RETRIES_HEADER, retriesHeader + 1);
+			List<Map<String, ?>> xDeath = (List<Map<String, ?>>) headers.get(X_DEATH_HEADER);
+			String exchange = (String) xDeath.get(0).get("exchange");
+			List<String> routingKeys = (List<String>) xDeath.get(0).get("routing-keys");
+			this.rabbitTemplate.send(exchange, routingKeys.get(0), failedMessage);
+		}
+		else {
+			this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+		}
+	}
+
+	@Bean
+	public Queue parkingLot() {
+		return new Queue(PARKING_LOT);
+	}
+
+}

republishToDlq=true

When republishToDlq is true, the republishing recoverer adds the original exchange and routing key to headers.

@SpringBootApplication
+public class ReRouteDlqApplication {
+
+	private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+	private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+	private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+	private static final String X_RETRIES_HEADER = "x-retries";
+
+	private static final String X_ORIGINAL_EXCHANGE_HEADER = RepublishMessageRecoverer.X_ORIGINAL_EXCHANGE;
+
+	private static final String X_ORIGINAL_ROUTING_KEY_HEADER = RepublishMessageRecoverer.X_ORIGINAL_ROUTING_KEY;
+
+	public static void main(String[] args) throws Exception {
+		ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+		System.out.println("Hit enter to terminate");
+		System.in.read();
+		context.close();
+	}
+
+	@Autowired
+	private RabbitTemplate rabbitTemplate;
+
+	@RabbitListener(queues = DLQ)
+	public void rePublish(Message failedMessage) {
+		Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
+		Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
+		if (retriesHeader == null) {
+			retriesHeader = Integer.valueOf(0);
+		}
+		if (retriesHeader < 3) {
+			headers.put(X_RETRIES_HEADER, retriesHeader + 1);
+			String exchange = (String) headers.get(X_ORIGINAL_EXCHANGE_HEADER);
+			String originalRoutingKey = (String) headers.get(X_ORIGINAL_ROUTING_KEY_HEADER);
+			this.rabbitTemplate.send(exchange, originalRoutingKey, failedMessage);
+		}
+		else {
+			this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+		}
+	}
+
+	@Bean
+	public Queue parkingLot() {
+		return new Queue(PARKING_LOT);
+	}
+
+}
Prev Up Next
37. Apache Kafka Binder Home Part VI. Spring Cloud Bus
\ No newline at end of file diff --git a/Edgware.SR6/multi/multi__router_and_filter_zuul.html b/Edgware.SR6/multi/multi__router_and_filter_zuul.html new file mode 100644 index 00000000..201c9072 --- /dev/null +++ b/Edgware.SR6/multi/multi__router_and_filter_zuul.html @@ -0,0 +1,598 @@ + + + 19. Router and Filter: Zuul
19. Router and Filter: Zuul
Prev Part III. Spring Cloud Netflix Next

19. Router and Filter: Zuul

Routing in an integral part of a microservice architecture. For example, / may be mapped to your web application, /api/users is mapped to the user service and /api/shop is mapped to the shop service. Zuul is a JVM based router and server side load balancer by Netflix.

Netflix uses Zuul for the following:

  • Authentication
  • Insights
  • Stress Testing
  • Canary Testing
  • Dynamic Routing
  • Service Migration
  • Load Shedding
  • Security
  • Static Response handling
  • Active/Active traffic management

Zuul’s rule engine allows rules and filters to be written in essentially any JVM language, with built in support for Java and Groovy.

[Note]Note

The configuration property zuul.max.host.connections has been replaced by two new properties, zuul.host.maxTotalConnections and zuul.host.maxPerRouteConnections which default to 200 and 20 respectively.

[Note]Note

Default Hystrix isolation pattern (ExecutionIsolationStrategy) for all routes is SEMAPHORE. zuul.ribbonIsolationStrategy can be changed to THREAD if this isolation pattern is preferred.

19.1 How to Include Zuul

To include Zuul in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-zuul. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

19.2 Embedded Zuul Reverse Proxy

Spring Cloud has created an embedded Zuul proxy to ease the +development of a very common use case where a UI application wants to +proxy calls to one or more back end services. This feature is useful +for a user interface to proxy to the backend services it requires, +avoiding the need to manage CORS and authentication concerns +independently for all the backends.

To enable it, annotate a Spring Boot main class with +@EnableZuulProxy, and this forwards local calls to the appropriate +service. By convention, a service with the ID "users", will +receive requests from the proxy located at /users (with the prefix +stripped). The proxy uses Ribbon to locate an instance to forward to +via discovery, and all requests are executed in a +hystrix command, so +failures will show up in Hystrix metrics, and once the circuit is open +the proxy will not try to contact the service.

[Note]Note

the Zuul starter does not include a discovery client, so for +routes based on service IDs you need to provide one of those +on the classpath as well (e.g. Eureka is one choice).

To skip having a service automatically added, set +zuul.ignored-services to a list of service id patterns. If a service +matches a pattern that is ignored, but also included in the explicitly +configured routes map, then it will be unignored. Example:

application.yml.  +

 zuul:
+  ignoredServices: '*'
+  routes:
+    users: /myusers/**

+

In this example, all services are ignored except "users".

To augment or change +the proxy routes, you can add external configuration like the +following:

application.yml.  +

 zuul:
+  routes:
+    users: /myusers/**

+

This means that http calls to "/myusers" get forwarded to the "users" +service (for example "/myusers/101" is forwarded to "/101").

To get more fine-grained control over a route you can specify the path +and the serviceId independently:

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      serviceId: users_service

+

This means that http calls to "/myusers" get forwarded to the +"users_service" service. The route has to have a "path" which can be +specified as an ant-style pattern, so "/myusers/*" only matches one +level, but "/myusers/**" matches hierarchically.

The location of the backend can be specified as either a "serviceId" +(for a service from discovery) or a "url" (for a physical location), e.g.

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      url: https://example.com/users_service

+

These simple url-routes don’t get executed as a HystrixCommand nor do they loadbalance multiple URLs with Ribbon. +To achieve this, you can specify a serviceId with a static list of servers:

application.yml.  +

zuul:
+  routes:
+    echo:
+      path: /myusers/**
+      serviceId: myusers-service
+      stripPrefix: true
+
+hystrix:
+  command:
+    myusers-service:
+      execution:
+        isolation:
+          thread:
+            timeoutInMilliseconds: ...
+
+myusers-service:
+  ribbon:
+    NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList
+    listOfServers: https://example1.com,http://example2.com
+    ConnectTimeout: 1000
+    ReadTimeout: 3000
+    MaxTotalHttpConnections: 500
+    MaxConnectionsPerHost: 100

+

Another method is specifiying a service-route and configure a Ribbon client for the +serviceId (this requires disabling Eureka support in Ribbon: +see above for more information), e.g.

application.yml.  +

zuul:
+  routes:
+    users:
+      path: /myusers/**
+      serviceId: users
+
+ribbon:
+  eureka:
+    enabled: false
+
+users:
+  ribbon:
+    listOfServers: example.com,google.com

+

You can provide convention between serviceId and routes using +regexmapper. It uses regular expression named groups to extract +variables from serviceId and inject them into a route pattern.

ApplicationConfiguration.java.  +

@Bean
+public PatternServiceRouteMapper serviceRouteMapper() {
+    return new PatternServiceRouteMapper(
+        "(?<name>^.+)-(?<version>v.+$)",
+        "${version}/${name}");
+}

+

This means that a serviceId "myusers-v1" will be mapped to route +"/v1/myusers/**". Any regular expression is accepted but all named +groups must be present in both servicePattern and routePattern. If +servicePattern does not match a serviceId, the default behavior is +used. In the example above, a serviceId "myusers" will be mapped to route +"/myusers/**" (no version detected) This feature is disabled by +default and only applies to discovered services.

To add a prefix to all mappings, set zuul.prefix to a value, such as +/api. The proxy prefix is stripped from the request before the +request is forwarded by default (switch this behaviour off with +zuul.stripPrefix=false). You can also switch off the stripping of +the service-specific prefix from individual routes, e.g.

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      stripPrefix: false

+

[Note]Note

zuul.stripPrefix only applies to the prefix set in zuul.prefix. It does not have any effect on prefixes +defined within a given route’s path.

In this example, requests to "/myusers/101" will be forwarded to "/myusers/101" on the "users" service.

The zuul.routes entries actually bind to an object of type ZuulProperties. If you +look at the properties of that object you will see that it also has a "retryable" flag. +Set that flag to "true" to have the Ribbon client automatically retry failed requests +(and if you need to you can modify the parameters of the retry operations using +the Ribbon client configuration).

The X-Forwarded-Host header is added to the forwarded requests by +default. To turn it off set zuul.addProxyHeaders = false. The +prefix path is stripped by default, and the request to the backend +picks up a header "X-Forwarded-Prefix" ("/myusers" in the examples +above).

An application with @EnableZuulProxy could act as a standalone +server if you set a default route ("/"), for example zuul.route.home: +/ would route all traffic (i.e. "/**") to the "home" service.

If more fine-grained ignoring is needed, you can specify specific patterns to ignore. +These patterns are evaluated at the start of the route location process, which +means prefixes should be included in the pattern to warrant a match. Ignored patterns +span all services and supersede any other route specification.

application.yml.  +

 zuul:
+  ignoredPatterns: /**/admin/**
+  routes:
+    users: /myusers/**

+

This means that all calls such as "/myusers/101" will be forwarded to "/101" on the "users" service. +But calls including "/admin/" will not resolve.

[Warning]Warning

If you need your routes to have their order preserved you need to use a YAML +file as the ordering will be lost using a properties file. For example:

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+    legacy:
+      path: /**

+

If you were to use a properties file, the legacy path may end up in front of the users +path rendering the users path unreachable.

19.3 Zuul Http Client

The default HTTP client used by zuul is now backed by the Apache HTTP Client instead of the +deprecated Ribbon RestClient. To use RestClient or to use the okhttp3.OkHttpClient set +ribbon.restclient.enabled=true or ribbon.okhttp.enabled=true respectively. If you would +like to customize the Apache HTTP client or the OK HTTP client provide a bean of type +ClosableHttpClient or OkHttpClient.

19.4 Cookies and Sensitive Headers

It’s OK to share headers between services in the same system, but you +probably don’t want sensitive headers leaking downstream into external +servers. You can specify a list of ignored headers as part of the +route configuration. Cookies play a special role because they have +well-defined semantics in browsers, and they are always to be treated +as sensitive. If the consumer of your proxy is a browser, then cookies +for downstream services also cause problems for the user because they +all get jumbled up (all downstream services look like they come from +the same place).

If you are careful with the design of your services, for example if +only one of the downstream services sets cookies, then you might be +able to let them flow from the backend all the way up to the +caller. Also, if your proxy sets cookies and all your back end +services are part of the same system, it can be natural to simply +share them (and for instance use Spring Session to link them up to some +shared state). Other than that, any cookies that get set by downstream +services are likely to be not very useful to the caller, so it is +recommended that you make (at least) "Set-Cookie" and "Cookie" into +sensitive headers for routes that are not part of your domain. Even +for routes that are part of your domain, try to think carefully +about what it means before allowing cookies to flow between them and +the proxy.

The sensitive headers can be configured as a comma-separated list per +route, e.g.

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      sensitiveHeaders: Cookie,Set-Cookie,Authorization
+      url: https://downstream

+

[Note]Note

this is the default value for sensitiveHeaders, so you don’t +need to set it unless you want it to be different. N.B. this is new in +Spring Cloud Netflix 1.1 (in 1.0 the user had no control over headers +and all cookies flow in both directions).

The sensitiveHeaders are a blacklist and the default is not empty, +so to make Zuul send all headers (except the "ignored" ones) you would +have to explicitly set it to the empty list. This is necessary if you +want to pass cookie or authorization headers to your back end. Example:

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      sensitiveHeaders:
+      url: https://downstream

+

Sensitive headers can also be set globally by setting zuul.sensitiveHeaders. If sensitiveHeaders is set on a route, this will override the global sensitiveHeaders setting.

19.5 Ignored Headers

In addition to the per-route sensitive headers, you can set a global +value for zuul.ignoredHeaders for values that should be discarded +(both request and response) during interactions with downstream +services. By default these are empty, if Spring Security is not on the +classpath, and otherwise they are initialized to a set of well-known +"security" headers (e.g. involving caching) as specified by Spring +Security. The assumption in this case is that the downstream services +might add these headers too, and we want the values from the proxy. +To not discard these well known security headers in case Spring Security is on the classpath you can set zuul.ignoreSecurityHeaders to false. This can be useful if you disabled the HTTP Security response headers in Spring Security and want the values provided by downstream services

19.6 Management Endpoints

If you are using @EnableZuulProxy with the Spring Boot Actuator you +will enable (by default) two additional endpoints:

  • Routes
  • Filters

19.6.1 Routes Endpoint

A GET to the routes endpoint at /routes will return a list of the mapped +routes:

GET /routes.  +

{
+  /stores/**: "http://localhost:8081"
+}

+

Additional route details can be requested by adding the ?format=details query +string to /routes. This will produce the following output:

GET /routes?format=details.  +

{
+  "/stores/**": {
+    "id": "stores",
+    "fullPath": "/stores/**",
+    "location": "http://localhost:8081",
+    "path": "/**",
+    "prefix": "/stores",
+    "retryable": false,
+    "customSensitiveHeaders": false,
+    "prefixStripped": true
+  }
+}

+

A POST will force a refresh of the existing routes (e.g. in +case there have been changes in the service catalog). You can disable +this endpoint by setting endpoints.routes.enabled to false.

[Note]Note

the routes should respond automatically to changes in the +service catalog, but the POST to /routes is a way to force the change +to happen immediately.

19.6.2 Filters Endpoint

A GET to the filters endpoint at /filters will return a map of Zuul +filters by type. For each filter type in the map, you will find a list +of all the filters of that type, along with their details.

19.7 Strangulation Patterns and Local Forwards

A common pattern when migrating an existing application or API is to +"strangle" old endpoints, slowly replacing them with different +implementations. The Zuul proxy is a useful tool for this because you +can use it to handle all traffic from clients of the old endpoints, +but redirect some of the requests to new ones.

Example configuration:

application.yml.  +

 zuul:
+  routes:
+    first:
+      path: /first/**
+      url: https://first.example.com
+    second:
+      path: /second/**
+      url: forward:/second
+    third:
+      path: /third/**
+      url: forward:/3rd
+    legacy:
+      path: /**
+      url: https://legacy.example.com

+

In this example we are strangling the "legacy" app which is mapped to +all requests that do not match one of the other patterns. Paths in +/first/** have been extracted into a new service with an external +URL. And paths in /second/** are forwarded so they can be handled +locally, e.g. with a normal Spring @RequestMapping. Paths in +/third/** are also forwarded, but with a different prefix +(i.e. /third/foo is forwarded to /3rd/foo).

[Note]Note

The ignored patterns aren’t completely ignored, they just +aren’t handled by the proxy (so they are also effectively forwarded +locally).

19.8 Uploading Files through Zuul

If you @EnableZuulProxy you can use the proxy paths to +upload files and it should just work as long as the files +are small. For large files there is an alternative path +which bypasses the Spring DispatcherServlet (to +avoid multipart processing) in "/zuul/*". I.e. if +zuul.routes.customers=/customers/** then you can +POST large files to "/zuul/customers/*". The servlet +path is externalized via zuul.servletPath. Extremely +large files will also require elevated timeout settings +if the proxy route takes you through a Ribbon load +balancer, e.g.

application.yml.  +

hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 60000
+ribbon:
+  ConnectTimeout: 3000
+  ReadTimeout: 60000

+

Note that for streaming to work with large files, you need to use chunked encoding in the request (which some browsers +do not do by default). E.g. on the command line:

$ curl -v -H "Transfer-Encoding: chunked" \
+    -F "file=@mylarge.iso" localhost:9999/zuul/simple/file

19.9 Query String Encoding

When processing the incoming request, query params are decoded so they can be available for possible modifications in +Zuul filters. They are then re-encoded when building the backend request in the route filters. The result +can be different than the original input if it was encoded using Javascript’s encodeURIComponent() method for example. +While this causes no issues in most cases, some web servers can be picky with the encoding of complex query string.

To force the original encoding of the query string, it is possible to pass a special flag to ZuulProperties so +that the query string is taken as is with the HttpServletRequest::getQueryString method :

application.yml.  +

 zuul:
+  forceOriginalQueryStringEncoding: true

+

Note: This special flag only works with SimpleHostRoutingFilter and you loose the ability to easily override +query parameters with RequestContext.getCurrentContext().setRequestQueryParams(someOverriddenParameters) since +the query string is now fetched directly on the original HttpServletRequest.

19.10 Plain Embedded Zuul

You can also run a Zuul server without the proxying, or switch on parts of the proxying platform selectively, if you +use @EnableZuulServer (instead of @EnableZuulProxy). Any beans that you add to the application of type ZuulFilter +will be installed automatically, as they are with @EnableZuulProxy, but without any of the proxy filters being added +automatically.

In this case the routes into the Zuul server are still specified by +configuring "zuul.routes.*", but there is no service +discovery and no proxying, so the "serviceId" and "url" settings are +ignored. For example:

application.yml.  +

 zuul:
+  routes:
+    api: /api/**

+

maps all paths in "/api/**" to the Zuul filter chain.

19.11 Disable Zuul Filters

Zuul for Spring Cloud comes with a number of ZuulFilter beans enabled by default +in both proxy and server mode. See the zuul filters package for the +possible filters that are enabled. If you want to disable one, simply set +zuul.<SimpleClassName>.<filterType>.disable=true. By convention, the package after +filters is the Zuul filter type. For example to disable +org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter set +zuul.SendResponseFilter.post.disable=true.

19.12 Providing Hystrix Fallbacks For Routes

When a circuit for a given route in Zuul is tripped you can provide a fallback response +by creating a bean of type ZuulFallbackProvider. Within this bean you need to specify +the route ID the fallback is for and provide a ClientHttpResponse to return +as a fallback. Here is a very simple ZuulFallbackProvider implementation.

class MyFallbackProvider implements ZuulFallbackProvider {
+    @Override
+    public String getRoute() {
+        return "customers";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return HttpStatus.OK;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return 200;
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return "OK";
+            }
+
+            @Override
+            public void close() {
+
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}

And here is what the route configuration would look like.

zuul:
+  routes:
+    customers: /customers/**

If you would like to provide a default fallback for all routes than you can create a bean of +type ZuulFallbackProvider and have the getRoute method return * or null.

class MyFallbackProvider implements ZuulFallbackProvider {
+    @Override
+    public String getRoute() {
+        return "*";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return HttpStatus.OK;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return 200;
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return "OK";
+            }
+
+            @Override
+            public void close() {
+
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}

If you would like to choose the response based on the cause of the failure use FallbackProvider which will replace ZuulFallbackProvder in future versions.

class MyFallbackProvider implements FallbackProvider {
+
+    @Override
+    public String getRoute() {
+        return "*";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse(final Throwable cause) {
+        if (cause instanceof HystrixTimeoutException) {
+            return response(HttpStatus.GATEWAY_TIMEOUT);
+        } else {
+            return fallbackResponse();
+        }
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return response(HttpStatus.INTERNAL_SERVER_ERROR);
+    }
+
+    private ClientHttpResponse response(final HttpStatus status) {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return status;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return status.value();
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return status.getReasonPhrase();
+            }
+
+            @Override
+            public void close() {
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}

19.13 Zuul Timeouts

19.13.1 Service Discovery Configuration

If Zuul is using service discovery there are two timeouts you need to be concerned +with, the Hystrix timeout (since all routes are wrapped in Hystrix commands by default) +and the Ribbon timeout. The Hystrix timeout needs to take into account the Ribbon +read and connect timeout PLUS the total number of retries that will happen for that +service. By default Spring Cloud Zuul will do its best to calculate the Hystrix timeout +for you UNLESS you specify the Hystrix timeout explicitly.

The Hystrix timeout is calculated using the following formula:

(ribbon.ConnectTimeout + ribbon.ReadTimeout) * (ribbon.MaxAutoRetries + 1) * (ribbon.MaxAutoRetriesNextServer + 1)

As an example, if you set the following properties in your application properties

application.yml.  +

ribbon:
+  ReadTimeout:100
+  ConnectTimeout:500
+  MaxAutoRetries:1
+  MaxAutoRetriesNextServer:1

+

Then the Hystrix timeout (for all routes in this case) will be set to 2400ms.

[Note]Note

You can configure the Hystrix timeout for individual routes using service.ribbon.* properties.

[Note]Note

If you choose to not configure the above properties than the default values will be used therefore the +default Hystrix timeout will be set to 4000ms.

If you set hystrix.command.commandKey.execution.isolation.thread.timeoutInMilliseconds, where +commandKey is the route id, or set hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds +than these values will be used for the Hystrix timeout regardless of what you have set for the ribbon.* properties. +If you set either of these properties YOU are responsible for making sure it takes +into account the Ribbon connect and read timeouts as well as any retries that may happen.

19.13.2 URL Configuration

If you have configured Zuul routes by specifying URLs than you will need to use +zuul.host.connect-timeout-millis and zuul.host.socket-timeout-millis.

19.14 Rewriting Location header

If Zuul is fronting a web application then there may be a need to re-write the Location header when the web application redirects through a http status code of 3XX, otherwise the browser will end up redirecting to the web application’s url instead of the Zuul url. +A LocationRewriteFilter Zuul filter can be configured to re-write the Location header to the Zuul’s url, it also adds back the stripped global and route specific prefixes. The filter can be added the following way via a Spring Configuration file:

import org.springframework.cloud.netflix.zuul.filters.post.LocationRewriteFilter;
+...
+
+@Configuration
+@EnableZuulProxy
+public class ZuulConfig {
+    @Bean
+    public LocationRewriteFilter locationRewriteFilter() {
+        return new LocationRewriteFilter();
+    }
+}
[Warning]Warning

Use this filter with caution though, the filter acts on the Location header of ALL 3XX response codes which may not be appropriate in all scenarios, say if the user is redirecting to an external URL.

19.15 Zuul Developer Guide

For a general overview of how Zuul works, please see the Zuul Wiki.

19.15.1 The Zuul Servlet

Zuul is implemented as a Servlet. For the general cases, Zuul is embedded into the Spring Dispatch mechanism. This allows Spring MVC to be in control of the routing. In this case, Zuul is configured to buffer requests. If there is a need to go through Zuul without buffering requests (e.g. for large file uploads), the Servlet is also installed outside of the Spring Dispatcher. By default, this is located at /zuul. This path can be changed with the zuul.servlet-path property.

19.15.2 Zuul RequestContext

To pass information between filters, Zuul uses a RequestContext. Its data is held in a ThreadLocal specific to each request. Information about where to route requests, errors and the actual HttpServletRequest and HttpServletResponse are stored there. The RequestContext extends ConcurrentHashMap, so anything can be stored in the context. FilterConstants contains the keys that are used by the filters installed by Spring Cloud Netflix (more on these later).

19.15.3 @EnableZuulProxy vs. @EnableZuulServer

Spring Cloud Netflix installs a number of filters based on which annotation was used to enable Zuul. @EnableZuulProxy is a superset of @EnableZuulServer. In other words, @EnableZuulProxy contains all filters installed by @EnableZuulServer. The additional filters in the "proxy" enable routing functionality. If you want a "blank" Zuul, you should use @EnableZuulServer.

19.15.4 @EnableZuulServer Filters

Creates a SimpleRouteLocator that loads route definitions from Spring Boot configuration files.

The following filters are installed (as normal Spring Beans):

Pre filters:

  • ServletDetectionFilter: Detects if the request is through the Spring Dispatcher. Sets boolean with key FilterConstants.IS_DISPATCHER_SERVLET_REQUEST_KEY.
  • FormBodyWrapperFilter: Parses form data and reencodes it for downstream requests.
  • DebugFilter: if the debug request parameter is set, this filter sets RequestContext.setDebugRouting() and RequestContext.setDebugRequest() to true.

Route filters:

  • SendForwardFilter: This filter forwards requests using the Servlet RequestDispatcher. The forwarding location is stored in the RequestContext attribute FilterConstants.FORWARD_TO_KEY. This is useful for forwarding to endpoints in the current application.

Post filters:

  • SendResponseFilter: Writes responses from proxied requests to the current response.

Error filters:

  • SendErrorFilter: Forwards to /error (by default) if RequestContext.getThrowable() is not null. The default forwarding path (/error) can be changed by setting the error.path property.

19.15.5 @EnableZuulProxy Filters

Creates a DiscoveryClientRouteLocator that loads route definitions from a DiscoveryClient (like Eureka), as well as from properties. A route is created for each serviceId from the DiscoveryClient. As new services are added, the routes will be refreshed.

In addition to the filters described above, the following filters are installed (as normal Spring Beans):

Pre filters:

  • PreDecorationFilter: This filter determines where and how to route based on the supplied RouteLocator. It also sets various proxy-related headers for downstream requests.

Route filters:

  • RibbonRoutingFilter: This filter uses Ribbon, Hystrix and pluggable HTTP clients to send requests. Service ids are found in the RequestContext attribute FilterConstants.SERVICE_ID_KEY. This filter can use different HTTP clients. They are:

    • Apache HttpClient. This is the default client.
    • Squareup OkHttpClient v3. This is enabled by having the com.squareup.okhttp3:okhttp library on the classpath and setting ribbon.okhttp.enabled=true.
    • Netflix Ribbon HTTP client. This is enabled by setting ribbon.restclient.enabled=true. This client has limitations, such as it doesn’t support the PATCH method, but also has built-in retry.
  • SimpleHostRoutingFilter: This filter sends requests to predetermined URLs via an Apache HttpClient. URLs are found in RequestContext.getRouteHost().

19.15.6 Custom Zuul Filter examples

Most of the following "How to Write" examples below are included Sample Zuul Filters project. There are also examples of manipulating the request or response body in that repository.

19.15.7 How to Write a Pre Filter

Pre filters are used to set up data in the RequestContext for use in filters downstream. The main use case is to set information required for route filters.

public class QueryParamPreFilter extends ZuulFilter {
+	@Override
+	public int filterOrder() {
+		return PRE_DECORATION_FILTER_ORDER - 1; // run before PreDecoration
+	}
+
+	@Override
+	public String filterType() {
+		return PRE_TYPE;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		RequestContext ctx = RequestContext.getCurrentContext();
+		return !ctx.containsKey(FORWARD_TO_KEY) // a filter has already forwarded
+				&& !ctx.containsKey(SERVICE_ID_KEY); // a filter has already determined serviceId
+	}
+    @Override
+    public Object run() {
+        RequestContext ctx = RequestContext.getCurrentContext();
+		HttpServletRequest request = ctx.getRequest();
+		if (request.getParameter("foo") != null) {
+		    // put the serviceId in `RequestContext`
+    		ctx.put(SERVICE_ID_KEY, request.getParameter("foo"));
+    	}
+        return null;
+    }
+}

The filter above populates SERVICE_ID_KEY from the foo request parameter. In reality, it’s not a good idea to do that kind of direct mapping, but the service id should be looked up from the value of foo instead.

Now that SERVICE_ID_KEY is populated, PreDecorationFilter won’t run and RibbonRoutingFilter will. If you wanted to route to a full URL instead, call ctx.setRouteHost(url) instead.

To modify the path that routing filters will forward to, set the REQUEST_URI_KEY.

19.15.8 How to Write a Route Filter

Route filters are run after pre filters and are used to make requests to other services. Much of the work here is to translate request and response data to and from the client required model.

public class OkHttpRoutingFilter extends ZuulFilter {
+	@Autowired
+	private ProxyRequestHelper helper;
+
+	@Override
+	public String filterType() {
+		return ROUTE_TYPE;
+	}
+
+	@Override
+	public int filterOrder() {
+		return SIMPLE_HOST_ROUTING_FILTER_ORDER - 1;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		return RequestContext.getCurrentContext().getRouteHost() != null
+				&& RequestContext.getCurrentContext().sendZuulResponse();
+	}
+
+    @Override
+    public Object run() {
+		OkHttpClient httpClient = new OkHttpClient.Builder()
+				// customize
+				.build();
+
+		RequestContext context = RequestContext.getCurrentContext();
+		HttpServletRequest request = context.getRequest();
+
+		String method = request.getMethod();
+
+		String uri = this.helper.buildZuulRequestURI(request);
+
+		Headers.Builder headers = new Headers.Builder();
+		Enumeration<String> headerNames = request.getHeaderNames();
+		while (headerNames.hasMoreElements()) {
+			String name = headerNames.nextElement();
+			Enumeration<String> values = request.getHeaders(name);
+
+			while (values.hasMoreElements()) {
+				String value = values.nextElement();
+				headers.add(name, value);
+			}
+		}
+
+		InputStream inputStream = request.getInputStream();
+
+		RequestBody requestBody = null;
+		if (inputStream != null && HttpMethod.permitsRequestBody(method)) {
+			MediaType mediaType = null;
+			if (headers.get("Content-Type") != null) {
+				mediaType = MediaType.parse(headers.get("Content-Type"));
+			}
+			requestBody = RequestBody.create(mediaType, StreamUtils.copyToByteArray(inputStream));
+		}
+
+		Request.Builder builder = new Request.Builder()
+				.headers(headers.build())
+				.url(uri)
+				.method(method, requestBody);
+
+		Response response = httpClient.newCall(builder.build()).execute();
+
+		LinkedMultiValueMap<String, String> responseHeaders = new LinkedMultiValueMap<>();
+
+		for (Map.Entry<String, List<String>> entry : response.headers().toMultimap().entrySet()) {
+			responseHeaders.put(entry.getKey(), entry.getValue());
+		}
+
+		this.helper.setResponse(response.code(), response.body().byteStream(),
+				responseHeaders);
+		context.setRouteHost(null); // prevent SimpleHostRoutingFilter from running
+		return null;
+    }
+}

The above filter translates Servlet request information into OkHttp3 request information, executes an HTTP request, then translates OkHttp3 reponse information to the Servlet response. WARNING: this filter might have bugs and not function correctly.

19.15.9 How to Write a Post Filter

Post filters typically manipulate the response. In the filter below, we add a random UUID as the X-Foo header. Other manipulations, such as transforming the response body, are much more complex and compute-intensive.

public class AddResponseHeaderFilter extends ZuulFilter {
+	@Override
+	public String filterType() {
+		return POST_TYPE;
+	}
+
+	@Override
+	public int filterOrder() {
+		return SEND_RESPONSE_FILTER_ORDER - 1;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		return true;
+	}
+
+	@Override
+	public Object run() {
+		RequestContext context = RequestContext.getCurrentContext();
+    	HttpServletResponse servletResponse = context.getResponse();
+		servletResponse.addHeader("X-Foo", UUID.randomUUID().toString());
+		return null;
+	}
+}

19.15.10 How Zuul Errors Work

If an exception is thrown during any portion of the Zuul filter lifecycle, the error filters are executed. The SendErrorFilter is only run if RequestContext.getThrowable() is not null. It then sets specific javax.servlet.error.* attributes in the request and forwards the request to the Spring Boot error page.

19.15.11 Zuul Eager Application Context Loading

Zuul internally uses Ribbon for calling the remote url’s and Ribbon clients are by default lazily loaded up by Spring Cloud on first call. +This behavior can be changed for Zuul using the following configuration and will result in the child Ribbon related Application contexts being eagerly loaded up at application startup time.

application.yml.  +

zuul:
+  ribbon:
+    eager-load:
+      enabled: true

+

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59. Running examples
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59. Running examples

You can find the running examples deployed in the Pivotal Web Services. Check them out in the following links:

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58. Integrations Home Part VIII. Spring Cloud Consul
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76. Running Spring Cloud Services in Development
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76. Running Spring Cloud Services in Development

The Launcher CLI can be used to run common services like Eureka, +Config Server etc. from the command line. To list the available +services you can do spring cloud --list, and to launch a default set +of services just spring cloud. To choose the services to deploy, +just list them on the command line, e.g.

$ spring cloud eureka configserver h2 kafka stubrunner zipkin

Summary of supported deployables:

ServiceNameAddressDescription

eureka

Eureka Server

http://localhost:8761

Eureka server for service registration and discovery. All the other services show up in its catalog by default.

configserver

Config Server

http://localhost:8888

Spring Cloud Config Server running in the "native" profile and serving configuration from the local directory ./launcher

h2

H2 Database

http://localhost:9095 (console), jdbc:h2:tcp://localhost:9096/{data}

Relation database service. Use a file path for {data} (e.g. ./target/test) when you connect. Remember that you can add ;MODE=MYSQL or ;MODE=POSTGRESQL to connect with compatibility to other server types.

kafka

Kafka Broker

http://localhost:9091 (actuator endpoints), localhost:9092

 

hystrixdashboard

Hystrix Dashboard

http://localhost:7979

Any Spring Cloud app that declares Hystrix circuit breakers publishes metrics on /hystrix.stream. Type that address into the dashboard to visualize all the metrics,

dataflow

Dataflow Server

http://localhost:9393

Spring Cloud Dataflow server with UI at /admin-ui. Connect the Dataflow shell to target at root path.

zipkin

Zipkin Server

http://localhost:9411

Zipkin Server with UI for visualizing traces. Stores span data in memory and accepts them via HTTP POST of JSON data.

stubrunner

Stub Runner Boot

http://localhost:8750

Downloads WireMock stubs, starts WireMock and feeds the started servers with stored stubs. Pass stubrunner.ids to pass stub coordinates and then go to http://localhost:8750/stubs.

Each of these apps can be configured using a local YAML file with the same name (in the current +working directory or a subdirectory called "config" or in ~/.spring-cloud). E.g. in configserver.yml you might want to +do something like this to locate a local git repository for the backend:

configserver.yml.  +

spring:
+  profiles:
+    active: git
+  cloud:
+    config:
+      server:
+        git:
+          uri: file://${user.home}/dev/demo/config-repo

+

E.g. in Stub Runner app you could fetch stubs from your local .m2 in the following way.

stubrunner.yml.  +

stubrunner:
+  workOffline: true
+  ids:
+    - com.example:beer-api-producer:+:9876

+

76.1 Adding Additional Applications

Additional applications can be added to ./config/cloud.yml (not +./config.yml because that would replace the defaults), e.g. with

config/cloud.yml.  +

spring:
+  cloud:
+    launcher:
+      deployables:
+        source:
+          coordinates: maven://com.example:source:0.0.1-SNAPSHOT
+          port: 7000
+        sink:
+          coordinates: maven://com.example:sink:0.0.1-SNAPSHOT
+          port: 7001

+

when you list the apps:

$ spring cloud --list
+source sink configserver dataflow eureka h2 hystrixdashboard kafka stubrunner zipkin

(notice the additional apps at the start of the list).

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35. Samples
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35. Samples

For Spring Cloud Stream samples, please refer to the spring-cloud-stream-samples repository on GitHub.

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34. Metrics Emitter Home 36. Getting Started
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49. Sampling
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49. Sampling

In distributed tracing the data volumes can be very high so sampling +can be important (you usually don’t need to export all spans to get a +good picture of what is happening). Spring Cloud Sleuth has a +Sampler strategy that you can implement to take control of the +sampling algorithm. Samplers do not stop span (correlation) ids from +being generated, but they do prevent the tags and events being +attached and exported. By default you get a strategy that continues to +trace if a span is already active, but new ones are always marked as +non-exportable. If all your apps run with this sampler you will see +traces in logs, but not in any remote store. For testing the default +is often enough, and it probably is all you need if you are only using +the logs (e.g. with an ELK aggregator). If you are exporting span data +to Zipkin or Spring Cloud Stream, there is also an AlwaysSampler +that exports everything and a PercentageBasedSampler that samples a +fixed fraction of spans.

[Note]Note

the PercentageBasedSampler is the default if you are using +spring-cloud-sleuth-zipkin or spring-cloud-sleuth-stream. You can +configure the exports using spring.sleuth.sampler.percentage. The passed +value needs to be a double from 0.0 to 1.0 so it’s not a percentage. +For backwards compatibility reasons we’re not changing the property name.

A sampler can be installed just by creating a bean definition, e.g:

@Bean
+public Sampler defaultSampler() {
+	return new AlwaysSampler();
+}
[Tip]Tip

You can set the HTTP header X-B3-Flags to 1 or when doing messaging you can +set spanFlags header to 1. Then the current span will be forced to be exportable +regardless of the sampling decision.

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48. Features Home 50. Instrumentation
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55. Sending spans to Zipkin
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55. Sending spans to Zipkin

[Important]Important

spring-cloud-sleuth-stream is deprecated and should no longer be used. +If spring-cloud-sleuth-zipkin is on the classpath then the app will generate and collect Zipkin-compatible traces. +By default it sends them via HTTP to a Zipkin server on localhost (port 9411). If you depend +on spring-rabbit or spring-kafka your app will send traces to a broker instead of http.

By default if you add spring-cloud-starter-zipkin as a dependency to your project, +when the span is closed, it will be sent to Zipkin over HTTP. The communication +is asynchronous. You can configure the URL by setting the spring.zipkin.baseUrl +property as follows:

spring.zipkin.baseUrl: https://192.168.99.100:9411/

If you want to find Zipkin via service discovery it’s enough to pass the +Zipkin’s service id inside the URL. If you want to disable this feature +just set spring.zipkin.discoveryClientEnabled to false. +Example for `zipkinserver service id:

spring.zipkin.baseUrl: http://zipkinserver/

When this Discovery Client feature is enabled, Sleuth uses +LoadBalancerClient to find the URL of the Zipkin Server. It means +that you can set up the load balancing configuration e.g. via Ribbon.

zipkinserver:
+  ribbon:
+    ListOfServers: host1,host2

If you have web, rabbit or kafka together on the classpath, you might need +to pick the means by which you would like to send spans to zipkin. To do that +just set either web, rabbit or kafka to the spring.zipkin.sender.type property. +Example for web:

spring.zipkin.sender.type: web

To customize the RestTemplate that sends spans to Zipkin via HTTP, you can register +the ZipkinRestTemplateCustomizer bean.

@Configuration
+class MyConfig {
+	@Bean ZipkinRestTemplateCustomizer myCustomizer() {
+		return new ZipkinRestTemplateCustomizer() {
+			@Override
+			void customize(RestTemplate restTemplate) {
+				// customize the RestTemplate
+			}
+		};
+	}
+}

If, however, you would like to control the full process of creating the RestTemplate +object, you will have to create a bean of zipkin2.reporter.Sender type.

	@Bean Sender myRestTemplateSender(ZipkinProperties zipkin,
+			ZipkinRestTemplateCustomizer zipkinRestTemplateCustomizer) {
+		RestTemplate restTemplate = mySuperCustomRestTemplate();
+		zipkinRestTemplateCustomizer.customize(restTemplate);
+		return myCustomSender(zipkin, restTemplate);
+	}
Prev Up Next
54. Customizations Home 56. Span Data as Messages
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115. Serverless Platform Adapters
Prev Part XV. Spring Cloud Function Next

115. Serverless Platform Adapters

As well as being able to run as a standalone process, a Spring Cloud +Function application can be adapted to run one of the existing +serverless platforms. In the project there are adapters for +AWS +Lambda, +Azure, +and +Apache +OpenWhisk. The Oracle Fn platform +has its own Spring Cloud Function adapter. And +Riff supports Java functions and its +Java Function +Invoker acts natively is an adapter for Spring Cloud Function jars.

115.1 AWS Lambda

The AWS adapter takes a Spring Cloud Function app and converts it to a form that can run in AWS Lambda.

115.1.1 Introduction

The adapter has a couple of generic request handlers that you can use. The most generic is SpringBootStreamHandler, which uses a Jackson ObjectMapper provided by Spring Boot to serialize and deserialize the objects in the function. There is also a SpringBootRequestHandler which you can extend, and provide the input and output types as type parameters (enabling AWS to inspect the class and do the JSON conversions itself).

If your app has more than one @Bean of type Function etc. then you can choose the one to use by configuring function.name (e.g. as FUNCTION_NAME environment variable in AWS). The functions are extracted from the Spring Cloud FunctionCatalog (searching first for Function then Consumer and finally Supplier).

115.1.2 Notes on JAR Layout

You don’t need the Spring Cloud Function Web or Stream adapter at runtime in Lambda, so you might need to exclude those before you create the JAR you send to AWS. A Lambda application has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample). The sample app creates 2 jar files, one with an aws classifier for deploying in Lambda, and one executable (thin) jar that includes spring-cloud-function-web at runtime. Spring Cloud Function will try and locate a "main class" for you from the JAR file manifest, using the Start-Class attribute (which will be added for you by the Spring Boot tooling if you use the starter parent). If there is no Start-Class in your manifest you can use an environment variable MAIN_CLASS when you deploy the function to AWS.

115.1.3 Upload

Build the sample under spring-cloud-function-samples/function-sample-aws and upload the -aws jar file to Lambda. The handler can be example.Handler or org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler (FQN of the class, not a method reference, although Lambda does accept method references).

./mvnw -U clean package

Using the AWS command line tools it looks like this:

aws lambda create-function --function-name Uppercase --role arn:aws:iam::[USERID]:role/service-role/[ROLE] --zip-file fileb://function-sample-aws/target/function-sample-aws-1.0.2.RELEASE-aws.jar --handler org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler --description "Spring Cloud Function Adapter Example" --runtime java8 --region us-east-1 --timeout 30 --memory-size 1024 --publish

The input type for the function in the AWS sample is a Foo with a single property called "value". So you would need this to test it:

{
+  "value": "test"
+}

115.1.4 Platfom Specific Features

HTTP and API Gateway

AWS has some platform-specific data types, including batching of messages, which is much more efficient than processing each one individually. To make use of these types you can write a function that depends on those types. Or you can rely on Spring to extract the data from the AWS types and convert it to a Spring Message. To do this you tell AWS that the function is of a specific generic handler type (depending on the AWS service) and provide a bean of type Function<Message<S>,Message<T>>, where S and T are your business data types. If there is more than one bean of type Function you may also need to configure the Spring Boot property function.name to be the name of the target bean (e.g. use FUNCTION_NAME as an environment variable).

The supported AWS services and generic handler types are listed below:

ServiceAWS TypesGeneric Handler 

API Gateway

APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent

org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler

 

Kinesis

KinesisEvent

org.springframework.cloud.function.adapter.aws.SpringBootKinesisEventHandler

 

For example, to deploy behind an API Gateway, use --handler org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler in your AWS command line (in via the UI) and define a @Bean of type Function<Message<Foo>,Message<Bar>> where Foo and Bar are POJO types (the data will be marshalled and unmarshalled by AWS using Jackson).

115.2 Azure Functions

The Azure adapter bootstraps a Spring Cloud Function context and channels function calls from the Azure framework into the user functions, using Spring Boot configuration where necessary. Azure Functions has quite a unique, but invasive programming model, involving annotations in user code that are specific to the platform. The Spring Cloud Function Azure adapter trades the convenience of these annotations for portability of the function implementations. Instead of using the annotations you have to write some JSON by hand (at least for now) to guide the platform to call the right methods in the adapter.

This project provides an adapter layer for a Spring Cloud Function application onto Azure. +You can write an app with a single @Bean of type Function and it will be deployable in Azure if you get the JAR file laid out right.

The adapter has a generic HTTP request handler that you can use optionally. +There is a AzureSpringBootRequestHandler which you must extend, and provide the input and output types as type parameters (enabling Azure to inspect the class and do the JSON conversions itself).

If your app has more than one @Bean of type Function etc. then you can choose the one to use by configuring function.name. +The functions are extracted from the Spring Cloud FunctionCatalog.

115.2.1 Notes on JAR Layout

You don’t need the Spring Cloud Function Web at runtime in Azure, so you need to exclude this before you create the JAR you deploy to Azure. +A function application on Azure has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample here). +The sample app creates the shaded jar file, with an azure classifier for deploying in Azure.

115.2.2 JSON Configuration

The Azure tooling needs to find some JSON configuration files to tell it how to deploy and integrate the function (e.g. which Java class to use as the entry point, and which triggers to use). Those files can be created with the Maven plugin for a non-Spring function, but the tooling doesn’t work yet with the adapter in its current form. There is an example function.json in the sample which hooks the function up as an HTTP endpoint:

{
+  "scriptFile" : "../function-sample-azure-1.0.2.RELEASE-azure.jar",
+  "entryPoint" : "example.FooHandler.execute",
+  "bindings" : [ {
+    "type" : "httpTrigger",
+    "name" : "foo",
+    "direction" : "in",
+    "authLevel" : "anonymous",
+    "methods" : [ "get", "post" ]
+  }, {
+    "type" : "http",
+    "name" : "$return",
+    "direction" : "out"
+  } ],
+  "disabled" : false
+}

115.2.3 Build

./mvnw -U clean package

115.2.4 Running the sample

You can run the sample locally, just like the other Spring Cloud Function samples:

and curl -H "Content-Type: text/plain" localhost:8080/function -d '{"value": "hello foobar"}'.

You will need the az CLI app and some node.js fu (see https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven for more detail). To deploy the function on Azure runtime:

$ az login
+$ mvn azure-functions:deploy

On another terminal try this: curl https://<azure-function-url-from-the-log>/api/uppercase -d '{"value": "hello foobar!"}'. Please ensure that you use the right URL for the function above. Alternatively you can test the function in the Azure Dashboard UI (click on the function name, go to the right hand side and click "Test" and to the bottom right, "Run").

The input type for the function in the Azure sample is a Foo with a single property called "value". So you need this to test it with something like below:

{
+  "value": "foobar"
+}

115.3 Apache Openwhisk

The OpenWhisk adapter is in the form of an executable jar that can be used in a a docker image to be deployed to Openwhisk. The platform works in request-response mode, listening on port 8080 on a specific endpoint, so the adapter is a simple Spring MVC application.

115.3.1 Quick Start

Implement a POF (be sure to use the functions package):

package functions;
+
+import java.util.function.Function;
+
+public class Uppercase implements Function<String, String> {
+
+	public String apply(String input) {
+		return input.toUpperCase();
+	}
+}

Install it into your local Maven repository:

./mvnw clean install

Create a function.properties file that provides its Maven coordinates. For example:

dependencies.function: com.example:pof:0.0.1-SNAPSHOT

Copy the openwhisk runner JAR to the working directory (same directory as the properties file):

cp spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk/target/spring-cloud-function-adapter-openwhisk-1.0.2.RELEASE.jar runner.jar

Generate a m2 repo from the --thin.dryrun of the runner JAR with the above properties file:

java -jar -Dthin.root=m2 runner.jar --thin.name=function --thin.dryrun

Use the following Dockerfile:

FROM openjdk:8-jdk-alpine
+VOLUME /tmp
+COPY m2 /m2
+ADD runner.jar .
+ADD function.properties .
+ENV JAVA_OPTS=""
+ENTRYPOINT [ "java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "runner.jar", "--thin.root=/m2", "--thin.name=function", "--function.name=uppercase"]
+EXPOSE 8080
[Note]Note

you could use a Spring Cloud Function app, instead of just a jar with a POF in it, in which case you would have to change the way the app runs in the container so that it picks up the main class as a source file. For example, you could change the ENTRYPOINT above and add --spring.main.sources=com.example.SampleApplication.

Build the Docker image:

docker build -t [username/appname] .

Push the Docker image:

docker push [username/appname]

Use the OpenWhisk CLI (e.g. after vagrant ssh) to create the action:

wsk action create example --docker [username/appname]

Invoke the action:

wsk action invoke example --result --param payload foo
+{
+    "result": "FOO"
+}
Prev Up Next
114. Dynamic Compilation Home Part XVI. Appendix: Compendium of Configuration Properties
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11. Service Discovery: Eureka Clients
Prev Part III. Spring Cloud Netflix Next

11. Service Discovery: Eureka Clients

Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Eureka is the Netflix Service Discovery Server and Client. The server can be configured and deployed to be highly available, with each server replicating state about the registered services to the others.

11.1 How to Include Eureka Client

To include Eureka Client in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-eureka-client. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

11.2 Registering with Eureka

When a client registers with Eureka, it provides meta-data about itself +such as host and port, health indicator URL, home page etc. Eureka +receives heartbeat messages from each instance belonging to a service. +If the heartbeat fails over a configurable timetable, the instance is +normally removed from the registry.

Example eureka client:

@Configuration
+@ComponentScan
+@EnableAutoConfiguration
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello world";
+    }
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

(i.e. utterly normal Spring Boot app). By having spring-cloud-starter-netflix-eureka-client + on the classpath your application will automatically register with the Eureka Server. Configuration is required to +locate the Eureka server. Example:

application.yml.  +

eureka:
+  client:
+    serviceUrl:
+      defaultZone: http://localhost:8761/eureka/

+

where "defaultZone" is a magic string fallback value that provides the +service URL for any client that doesn’t express a preference +(i.e. it’s a useful default).

The default application name (service ID), virtual host and non-secure +port, taken from the Environment, are ${spring.application.name}, +${spring.application.name} and ${server.port} respectively.

Having spring-cloud-starter-netflix-eureka-client on the classpath +makes the app into both a Eureka "instance" +(i.e. it registers itself) and a "client" (i.e. it can query the +registry to locate other services). The instance behaviour is driven +by eureka.instance.* configuration keys, but the defaults will be +fine if you ensure that your application has a +spring.application.name (this is the default for the Eureka service +ID, or VIP).

See EurekaInstanceConfigBean and EurekaClientConfigBean for more details of the configurable options.

To disable the Eureka Discovery Client you can set eureka.client.enabled to false.

11.3 Authenticating with the Eureka Server

HTTP basic authentication will be automatically added to your eureka +client if one of the eureka.client.serviceUrl.defaultZone URLs has +credentials embedded in it (curl style, like +http://user:password@localhost:8761/eureka). For more complex needs +you can create a @Bean of type DiscoveryClientOptionalArgs and +inject ClientFilter instances into it, all of which will be applied +to the calls from the client to the server.

[Note]Note

Because of a limitation in Eureka it isn’t possible to support +per-server basic auth credentials, so only the first set that are +found will be used.

11.4 Status Page and Health Indicator

The status page and health indicators for a Eureka instance default to +"/info" and "/health" respectively, which are the default locations of +useful endpoints in a Spring Boot Actuator application. You need to +change these, even for an Actuator application if you use a +non-default context path or servlet path +(e.g. server.servletPath=/foo) Example:

application.yml.  +

eureka:
+  instance:
+    statusPageUrlPath: ${server.servletPath}/info
+    healthCheckUrlPath: ${server.servletPath}/health

+

These links show up in the metadata that is consumed by clients, and +used in some scenarios to decide whether to send requests to your +application, so it’s helpful if they are accurate.

[Note]Note

In Dalston it was also required to set the status and health check URLs when changing +that management context path. This requirement was removed beinging in Edgware.

11.5 Registering a Secure Application

If your app wants to be contacted over HTTPS you can set two flags in +the EurekaInstanceConfig, viz +eureka.instance.[nonSecurePortEnabled,securePortEnabled]=[false,true] +respectively. This will make Eureka publish instance information +showing an explicit preference for secure communication. The Spring +Cloud DiscoveryClient will always return a URI starting with https for a +service configured this way, and the Eureka (native) instance +information will have a secure health check URL.

Because of the way +Eureka works internally, it will still publish a non-secure URL for +status and home page unless you also override those explicitly. +You can use placeholders to configure the eureka instance urls, +e.g.

application.yml.  +

eureka:
+  instance:
+    statusPageUrl: https://${eureka.hostname}/info
+    healthCheckUrl: https://${eureka.hostname}/health
+    homePageUrl: https://${eureka.hostname}/

+

(Note that ${eureka.hostname} is a native placeholder only available +in later versions of Eureka. You could achieve the same thing with +Spring placeholders as well, e.g. using ${eureka.instance.hostName}.)

[Note]Note

If your app is running behind a proxy, and the SSL termination +is in the proxy (e.g. if you run in Cloud Foundry or other platforms +as a service) then you will need to ensure that the proxy "forwarded" +headers are intercepted and handled by the application. An embedded +Tomcat container in a Spring Boot app does this automatically if it +has explicit configuration for the 'X-Forwarded-\*` headers. A sign +that you got this wrong will be that the links rendered by your app to +itself will be wrong (the wrong host, port or protocol).

11.6 Eureka’s Health Checks

By default, Eureka uses the client heartbeat to determine if a client is up. +Unless specified otherwise the Discovery Client will not propagate the +current health check status of the application per the Spring Boot Actuator. Which means +that after successful registration Eureka will always announce that the +application is in 'UP' state. This behaviour can be altered by enabling +Eureka health checks, which results in propagating application status +to Eureka. As a consequence every other application won’t be sending +traffic to application in state other then 'UP'.

application.yml.  +

eureka:
+  client:
+    healthcheck:
+      enabled: true

+

[Warning]Warning

eureka.client.healthcheck.enabled=true should only be set in application.yml. Setting the value in bootstrap.yml will cause undesirable side effects like registering in eureka with an UNKNOWN status.

If you require more control over the health checks, you may consider +implementing your own com.netflix.appinfo.HealthCheckHandler.

11.7 Eureka Metadata for Instances and Clients

It’s worth spending a bit of time understanding how the Eureka metadata works, so you can use it in a way that makes sense in your platform. There is standard metadata for things like hostname, IP address, port numbers, status page and health check. These are published in the service registry and used by clients to contact the services in a straightforward way. Additional metadata can be added to the instance registration in the eureka.instance.metadataMap, and this will be accessible in the remote clients, but in general will not change the behaviour of the client, unless it is made aware of the meaning of the metadata. There are a couple of special cases described below where Spring Cloud already assigns meaning to the metadata map.

11.7.1 Using Eureka on Cloud Foundry

Cloud Foundry has a global router so that all instances of the same app have the same hostname (it’s the same in other PaaS solutions with a similar architecture). This isn’t necessarily a barrier to using Eureka, but if you use the router (recommended, or even mandatory depending on the way your platform was set up), you need to explicitly set the hostname and port numbers (secure or non-secure) so that they use the router. You might also want to use instance metadata so you can distinguish between the instances on the client (e.g. in a custom load balancer). By default, the eureka.instance.instanceId is vcap.application.instance_id. For example:

application.yml.  +

eureka:
+  instance:
+    hostname: ${vcap.application.uris[0]}
+    nonSecurePort: 80

+

Depending on the way the security rules are set up in your Cloud Foundry instance, you might be able to register and use the IP address of the host VM for direct service-to-service calls. This feature is not (yet) available on Pivotal Web Services (PWS).

11.7.2 Using Eureka on AWS

If the application is planned to be deployed to an AWS cloud, then the Eureka instance will have to be configured to be AWS aware and this can be done by customizing the EurekaInstanceConfigBean the following way:

@Bean
+@Profile("!default")
+public EurekaInstanceConfigBean eurekaInstanceConfig(InetUtils inetUtils) {
+  EurekaInstanceConfigBean b = new EurekaInstanceConfigBean(inetUtils);
+  AmazonInfo info = AmazonInfo.Builder.newBuilder().autoBuild("eureka");
+  b.setDataCenterInfo(info);
+  return b;
+}

11.7.3 Changing the Eureka Instance ID

A vanilla Netflix Eureka instance is registered with an ID that is equal to its host name (i.e. only one service per host). Spring Cloud Eureka provides a sensible default that looks like this: ${spring.cloud.client.hostname}:${spring.application.name}:${spring.application.instance_id:${server.port}}}. For example myhost:myappname:8080.

Using Spring Cloud you can override this by providing a unique identifier in eureka.instance.instanceId. For example:

application.yml.  +

eureka:
+  instance:
+    instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}

+

With this metadata, and multiple service instances deployed on +localhost, the random value will kick in there to make the instance +unique. In Cloud Foundry the vcap.application.instance_id will be +populated automatically in a Spring Boot application, so the +random value will not be needed.

11.8 Using the EurekaClient

Once you have an app that is a discovery client you can use it to +discover service instances from the Eureka Server. One way to do that is to use the native +com.netflix.discovery.EurekaClient (as opposed to the Spring +Cloud DiscoveryClient), e.g.

@Autowired
+private EurekaClient discoveryClient;
+
+public String serviceUrl() {
+    InstanceInfo instance = discoveryClient.getNextServerFromEureka("STORES", false);
+    return instance.getHomePageUrl();
+}
[Tip]Tip

Don’t use the EurekaClient in @PostConstruct method or in a +@Scheduled method (or anywhere where the ApplicationContext might +not be started yet). It is initialized in a SmartLifecycle (with +phase=0) so the earliest you can rely on it being available is in +another SmartLifecycle with higher phase.

11.8.1 EurekaClient without Jersey

By default, EurekaClient uses Jersey for HTTP communication. If you wish +to avoid dependencies from Jersey, you can exclude it from your dependencies. +Spring Cloud will auto configure a transport client based on Spring +RestTemplate.

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-starter-eureka</artifactId>
+    <exclusions>
+        <exclusion>
+            <groupId>com.sun.jersey</groupId>
+            <artifactId>jersey-client</artifactId>
+        </exclusion>
+        <exclusion>
+            <groupId>com.sun.jersey</groupId>
+            <artifactId>jersey-core</artifactId>
+        </exclusion>
+        <exclusion>
+            <groupId>com.sun.jersey.contribs</groupId>
+            <artifactId>jersey-apache-client4</artifactId>
+        </exclusion>
+    </exclusions>
+</dependency>

11.9 Alternatives to the native Netflix EurekaClient

You don’t have to use the raw Netflix EurekaClient and usually it +is more convenient to use it behind a wrapper of some sort. Spring +Cloud has support for Feign (a REST client +builder) and also Spring RestTemplate using +the logical Eureka service identifiers (VIPs) instead of physical +URLs. To configure Ribbon with a fixed list of physical servers you +can simply set <client>.ribbon.listOfServers to a comma-separated +list of physical addresses (or hostnames), where <client> is the ID +of the client.

You can also use the org.springframework.cloud.client.discovery.DiscoveryClient +which provides a simple API for discovery clients that is not specific +to Netflix, e.g.

@Autowired
+private DiscoveryClient discoveryClient;
+
+public String serviceUrl() {
+    List<ServiceInstance> list = discoveryClient.getInstances("STORES");
+    if (list != null && list.size() > 0 ) {
+        return list.get(0).getUri();
+    }
+    return null;
+}

11.10 Why is it so Slow to Register a Service?

Being an instance also involves a periodic heartbeat to the registry +(via the client’s serviceUrl) with default duration 30 seconds. A +service is not available for discovery by clients until the instance, +the server and the client all have the same metadata in their local +cache (so it could take 3 heartbeats). You can change the period using +eureka.instance.leaseRenewalIntervalInSeconds and this will speed up +the process of getting clients connected to other services. In +production it’s probably better to stick with the default because +there are some computations internally in the server that make +assumptions about the lease renewal period.

11.11 Zones

If you have deployed Eureka clients to multiple zones than you may prefer that +those clients leverage services within the same zone before trying services +in another zone. To do this you need to configure your Eureka clients correctly.

First, you need to make sure you have Eureka servers deployed to each zone and that +they are peers of each other. See the section on zones and regions +for more information.

Next you need to tell Eureka which zone your service is in. You can do this using +the metadataMap property. For example if service 1 is deployed to both zone 1 +and zone 2 you would need to set the following Eureka properties in service 1

Service 1 in Zone 1

eureka.instance.metadataMap.zone = zone1
+eureka.client.preferSameZoneEureka = true

Service 1 in Zone 2

eureka.instance.metadataMap.zone = zone2
+eureka.client.preferSameZoneEureka = true
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Part III. Spring Cloud Netflix Home 12. Service Discovery: Eureka Server
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103. Service Registry Configuration
Prev Part XIV. Spring Cloud Vault Next

103. Service Registry Configuration

You can use a DiscoveryClient (such as from Spring Cloud Consul) to locate +a Vault server by setting spring.cloud.vault.discovery.enabled=true (default false). +The net result of that is that your apps need a bootstrap.yml (or an environment variable) +with the appropriate discovery configuration. +The benefit is that the Vault can change its co-ordinates, as long as the discovery service +is a fixed point. The default service id is vault but you can change that on the client with +spring.cloud.vault.discovery.serviceId.

The discovery client implementations all support some kind of metadata map +(e.g. for Eureka we have eureka.instance.metadataMap). Some additional properties of the service +may need to be configured in its service registration metadata so that clients can connect +correctly. Service registries that do not provide details about transport layer security +need to provide a scheme metadata entry to be set either to https or http. +If no scheme is configured and the service is not exposed as secure service, then +configuration defaults to spring.cloud.vault.scheme which is https when it’s not set.

spring.cloud.vault.discovery:
+    enabled: true
+    service-id: my-vault-service
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102. Configure PropertySourceLocator behavior Home 104. Vault Client Fail Fast
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6. Serving Alternative Formats
Prev Part II. Spring Cloud Config Next

6. Serving Alternative Formats

The default JSON format from the environment endpoints is perfect for +consumption by Spring applications because it maps directly onto the +Environment abstraction. If you prefer you can consume the same data +as YAML or Java properties by adding a suffix to the resource path +(".yml", ".yaml" or ".properties"). This can be useful for consumption +by applications that do not care about the structure of the JSON +endpoints, or the extra metadata they provide, for example an +application that is not using Spring might benefit from the simplicity +of this approach.

The YAML and properties representations have an additional flag +(provided as a boolean query parameter resolvePlaceholders) to +signal that placeholders in the source documents, in the standard +Spring ${…​} form, should be resolved in the output where possible +before rendering. This is a useful feature for consumers that don’t +know about the Spring placeholder conventions.

[Note]Note

there are limitations in using the YAML or properties formats, +mainly in relation to the loss of metadata. The JSON is structured as +an ordered list of property sources, for example, with names that +correlate with the source. The YAML and properties forms are coalesced +into a single map, even if the origin of the values has multiple +sources, and the names of the original source files are lost. The YAML +representation is not necessarily a faithful representation of the +YAML source in a backing repository either: it is constructed from a +list of flat property sources, and assumptions have to be made about +the form of the keys.

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5. Spring Cloud Config Server Home 7. Serving Plain Text
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7. Serving Plain Text
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7. Serving Plain Text

Instead of using the Environment abstraction (or one of the +alternative representations of it in YAML or properties format) your +applications might need generic plain text configuration files, +tailored to their environment. The Config Server provides these +through an additional endpoint at /{name}/{profile}/{label}/{path} +where "name", "profile" and "label" have the same meaning as the +regular environment endpoint, but "path" is a file name +(e.g. log.xml). The source files for this endpoint are located in +the same way as for the environment endpoints: the same search path is +used as for properties or YAML files, but instead of aggregating all +matching resources, only the first one to match is returned.

After a resource is located, placeholders in the normal format +(${…​}) are resolved using the effective Environment for the +application name, profile and label supplied. In this way the resource +endpoint is tightly integrated with the environment +endpoints. Example, if you have this layout for a GIT (or SVN) +repository:

application.yml
+nginx.conf

where nginx.conf looks like this:

server {
+    listen              80;
+    server_name         ${nginx.server.name};
+}

and application.yml like this:

nginx:
+  server:
+    name: example.com
+---
+spring:
+  profiles: development
+nginx:
+  server:
+    name: develop.com

then the /foo/default/master/nginx.conf resource looks like this:

server {
+    listen              80;
+    server_name         example.com;
+}

and /foo/development/master/nginx.conf like this:

server {
+    listen              80;
+    server_name         develop.com;
+}
[Note]Note

Just like the source files for environment configuration, the +"profile" is used to resolve the file name, so if you want a +profile-specific file then /*/development/*/logback.xml will be +resolved by a file called logback-development.xml (in preference +to logback.xml).

[Note]Note

If you do not want to supply the label and let the server use the default label, you can supply a useDefaultLabel request parameter. So, the above example for the default profile could look like /foo/default/nginx.conf?useDefaultLabel.

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6. Serving Alternative Formats Home 8. Embedding the Config Server
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83. Single Sign On
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83. Single Sign On

[Note]Note

All of the OAuth2 SSO and resource server features moved to Spring Boot +in version 1.3. You can find documentation in the +Spring Boot user guide.

This project provides automatic binding from CloudFoundry service +credentials to the Spring Boot features. If you have a CloudFoundry +service called "sso", for instance, with credentials containing +"client_id", "client_secret" and "auth_domain", it will bind +automatically to the Spring OAuth2 client that you enable with +@EnableOAuth2Sso (from Spring Boot). The name of the service can be +parameterized using spring.oauth2.sso.serviceId.

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82. Discovery Home Part XIII. Spring Cloud Contract
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56. Span Data as Messages
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56. Span Data as Messages

You can accumulate and send span data over +Spring Cloud Stream by +including the spring-cloud-sleuth-stream jar as a dependency, and +adding a Channel Binder implementation +(e.g. spring-cloud-starter-stream-rabbit for RabbitMQ or +spring-cloud-starter-stream-kafka for Kafka). This will +automatically turn your app into a producer of messages with payload +type Spans. The channel name to which the spans will be sent +is called sleuth.

56.1 Zipkin Consumer

[Important]Important

spring-cloud-sleuth-zipkin-stream is deprecated and should no longer be used. +Please use the OpenZipkin’s Zipkin server and set the environment variables +as presented here for rabbit (Zipkin 2.4.6) +or here for kafka (Zipkin 2.4.6)

There is a special convenience annotation for setting up a message consumer +for the Span data and pushing it into a Zipkin SpanStore. This application

@SpringBootApplication
+@EnableZipkinStreamServer
+public class Consumer {
+	public static void main(String[] args) {
+		SpringApplication.run(Consumer.class, args);
+	}
+}

will listen for the Span data on whatever transport you provide via a +Spring Cloud Stream Binder (e.g. include +spring-cloud-starter-stream-rabbit for RabbitMQ, and similar +starters exist for Redis and Kafka). If you add the following UI dependency

<groupId>io.zipkin.java</groupId>
+<artifactId>zipkin-autoconfigure-ui</artifactId>

Then you’ll have your app a +Zipkin server, which hosts +the UI and api on port 9411.

The default SpanStore is in-memory (good for demos and getting +started quickly). For a more robust solution you can add MySQL and +spring-boot-starter-jdbc to your classpath and enable the JDBC +SpanStore via configuration, e.g.:

spring:
+  rabbitmq:
+    host: ${RABBIT_HOST:localhost}
+  datasource:
+    schema: classpath:/mysql.sql
+    url: jdbc:mysql://${MYSQL_HOST:localhost}/test
+    username: root
+    password: root
+# Switch this on to create the schema on startup:
+    initialize: true
+    continueOnError: true
+  sleuth:
+    enabled: false
+zipkin:
+  storage:
+    type: mysql
[Note]Note

The @EnableZipkinStreamServer is also annotated with +@EnableZipkinServer so the process will also expose the standard +Zipkin server endpoints for collecting spans over HTTP, and for +querying in the Zipkin Web UI.

56.2 Custom Consumer

A custom consumer can also easily be implemented using +spring-cloud-sleuth-stream and binding to the SleuthSink. Example:

@EnableBinding(SleuthSink.class)
+@SpringBootApplication(exclude = SleuthStreamAutoConfiguration.class)
+@MessageEndpoint
+public class Consumer {
+
+    @ServiceActivator(inputChannel = SleuthSink.INPUT)
+    public void sink(Spans input) throws Exception {
+        // ... process spans
+    }
+}
[Note]Note

the sample consumer application above explicitly excludes +SleuthStreamAutoConfiguration so it doesn’t send messages to itself, +but this is optional (you might actually want to trace requests into +the consumer app).

In order to customize the polling mechanism you can create a bean of PollerMetadata type +with name equal to StreamSpanReporter.POLLER. Here you can find an example of such a configuration.

@Configuration
+public static class CustomPollerConfiguration {
+
+	@Bean(name = StreamSpanReporter.POLLER)
+	PollerMetadata customPoller() {
+		PollerMetadata poller = new PollerMetadata();
+		poller.setMaxMessagesPerPoll(500);
+		poller.setTrigger(new PeriodicTrigger(5000L));
+		return poller;
+	}
+}
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55. Sending spans to Zipkin Home 57. Metrics
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51. Span lifecycle
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51. Span lifecycle

You can do the following operations on the Span by means of org.springframework.cloud.sleuth.Tracer interface:

  • start - when you start a span its name is assigned and start timestamp is recorded.
  • close - the span gets finished (the end time of the span is recorded) and if +the span is exportable then it will be eligible for collection to Zipkin. +The span is also removed from the current thread.
  • continue - a new instance of span will be created whereas it will be a copy of the +one that it continues.
  • detach - the span doesn’t get stopped or closed. It only gets removed from the current thread.
  • create with explicit parent - you can create a new span and set an explicit parent to it
[Tip]Tip

Spring creates the instance of Tracer for you. In order to use it all you need is to just autowire it.

51.1 Creating and closing spans

You can manually create spans by using the Tracer interface.

// Start a span. If there was a span present in this thread it will become
+// the `newSpan`'s parent.
+Span newSpan = this.tracer.createSpan("calculateTax");
+try {
+	// ...
+	// You can tag a span
+	this.tracer.addTag("taxValue", taxValue);
+	// ...
+	// You can log an event on a span
+	newSpan.logEvent("taxCalculated");
+} finally {
+	// Once done remember to close the span. This will allow collecting
+	// the span to send it to Zipkin
+	this.tracer.close(newSpan);
+}

In this example we could see how to create a new instance of span. Assuming that there already +was a span present in this thread then it would become the parent of that span.

[Important]Important

Always clean after you create a span! Don’t forget to close a span if you want to send it to Zipkin.

[Important]Important

If your span contains a name greater than 50 chars, then that name will +be truncated to 50 chars. Your names have to be explicit and concrete. Big names lead to +latency issues and sometimes even thrown exceptions.

51.2 Continuing spans

Sometimes you don’t want to create a new span but you want to continue one. Example of such a +situation might be (of course it all depends on the use-case):

  • AOP - If there was already a span created before an aspect was reached then you might not want to create a new span.
  • Hystrix - executing a Hystrix command is most likely a logical part of the current processing. It’s in fact +only a technical implementation detail that you wouldn’t necessarily want to reflect in tracing as a separate being.

The continued instance of span is equal to the one that it continues:

Span continuedSpan = this.tracer.continueSpan(spanToContinue);
+assertThat(continuedSpan).isEqualTo(spanToContinue);

To continue a span you can use the Tracer interface.

// let's assume that we're in a thread Y and we've received
+// the `initialSpan` from thread X
+Span continuedSpan = this.tracer.continueSpan(initialSpan);
+try {
+	// ...
+	// You can tag a span
+	this.tracer.addTag("taxValue", taxValue);
+	// ...
+	// You can log an event on a span
+	continuedSpan.logEvent("taxCalculated");
+} finally {
+	// Once done remember to detach the span. That way you'll
+	// safely remove it from the current thread without closing it
+	this.tracer.detach(continuedSpan);
+}
[Important]Important

Always clean after you create a span! Don’t forget to detach a span if some work was done started in one + thread (e.g. thread X) and it’s waiting for other threads (e.g. Y, Z) to finish. + Then the spans in the threads Y, Z should be detached at the end of their work. When the results are collected + the span in thread X should be closed.

51.3 Creating spans with an explicit parent

There is a possibility that you want to start a new span and provide an explicit parent of that span. +Let’s assume that the parent of a span is in one thread and you want to start a new span in another thread. The +startSpan method of the Tracer interface is the method you are looking for.

// let's assume that we're in a thread Y and we've received
+// the `initialSpan` from thread X. `initialSpan` will be the parent
+// of the `newSpan`
+Span newSpan = this.tracer.createSpan("calculateCommission", initialSpan);
+try {
+	// ...
+	// You can tag a span
+	this.tracer.addTag("commissionValue", commissionValue);
+	// ...
+	// You can log an event on a span
+	newSpan.logEvent("commissionCalculated");
+} finally {
+	// Once done remember to close the span. This will allow collecting
+	// the span to send it to Zipkin. The tags and events set on the
+	// newSpan will not be present on the parent
+	this.tracer.close(newSpan);
+}
[Important]Important

After having created such a span remember to close it. Otherwise you will see a lot of warnings in your logs + related to the fact that you have a span present in the current thread other than the one you’re trying to close. + What’s worse your spans won’t get closed properly thus will not get collected to Zipkin.

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50. Instrumentation Home 52. Naming spans
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Part X. Spring Boot Cloud CLI
Prev   Next

Part X. Spring Boot Cloud CLI

Spring Boot CLI provides Spring +Boot command line features for Spring +Cloud. You can write Groovy scripts to run Spring Cloud component +applications (e.g. @EnableEurekaServer). You can also easily do +things like encryption and decryption to support Spring Cloud Config +clients with secret configuration values. With the Launcher CLI you +can launch services like Eureka, Zipkin, Config Server +conveniently all at once from the command line (very useful at +development time).

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

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74. Distributed Configuration with Zookeeper Home 75. Installation
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Part VI. Spring Cloud Bus
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Part VI. Spring Cloud Bus

Spring Cloud Bus links nodes of a distributed system with a lightweight message broker. This can then be used to broadcast state changes (e.g. configuration changes) or other management instructions. A key idea is that the Bus is like a distributed Actuator for a Spring Boot application that is scaled out, but it can also be used as a communication channel between apps. Starters are provided for an AMQP broker as the transport or for Kafka, but the same basic feature set (and some more depending on the transport) is on the roadmap for other transports.

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

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38. RabbitMQ Binder Home 39. Quick Start
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3. Spring Cloud Commons: Common Abstractions
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3. Spring Cloud Commons: Common Abstractions

Patterns such as service discovery, load balancing and circuit breakers lend themselves to a common abstraction layer that can be consumed by all Spring Cloud clients, independent of the implementation (e.g. discovery via Eureka or Consul).

3.1 @EnableDiscoveryClient

Commons provides the @EnableDiscoveryClient annotation. This looks for implementations of the DiscoveryClient interface via META-INF/spring.factories. Implementations of Discovery Client will add a configuration class to spring.factories under the org.springframework.cloud.client.discovery.EnableDiscoveryClient key. Examples of DiscoveryClient implementations: are Spring Cloud Netflix Eureka, Spring Cloud Consul Discovery and Spring Cloud Zookeeper Discovery.

By default, implementations of DiscoveryClient will auto-register the local Spring Boot server with the remote discovery server. This can be disabled by setting autoRegister=false in @EnableDiscoveryClient.

[Note]Note

The use of @EnableDiscoveryClient is no longer required. It is enough to just have a DiscoveryClient implementation +on the classpath to cause the Spring Boot application to register with the service discovery server.

3.1.1 Health Indicator

Commons creates a Spring Boot HealthIndicator that DiscoveryClient implementations can participate in by implementing DiscoveryHealthIndicator. To disable the composite HealthIndicator set spring.cloud.discovery.client.composite-indicator.enabled=false. A generic HealthIndicator based on DiscoveryClient is auto-configured (DiscoveryClientHealthIndicator). To disable it, set `spring.cloud.discovery.client.health-indicator.enabled=false. To disable the description field of the DiscoveryClientHealthIndicator set spring.cloud.discovery.client.health-indicator.include-description=false, otherwise it can bubble up as the description of the rolled up HealthIndicator.

3.2 ServiceRegistry

Commons now provides a ServiceRegistry interface which provides methods like register(Registration) and deregister(Registration) which allow you to provide custom registered services. Registration is a marker interface.

@Configuration
+@EnableDiscoveryClient(autoRegister=false)
+public class MyConfiguration {
+    private ServiceRegistry registry;
+
+    public MyConfiguration(ServiceRegistry registry) {
+        this.registry = registry;
+    }
+
+    // called via some external process, such as an event or a custom actuator endpoint
+    public void register() {
+        Registration registration = constructRegistration();
+        this.registry.register(registration);
+    }
+}

Each ServiceRegistry implementation has its own Registry implementation.

  • ZookeeperRegistration used with ZookeeperServiceRegistry
  • EurekaRegistration used with EurekaServiceRegistry
  • ConsulRegistration used with ConsulServiceRegistry

If you are using the ServiceRegistry interface, you are going to need to pass the +correct Registry implementation for the ServiceRegistry implementation you +are using.

3.2.1 ServiceRegistry Auto-Registration

By default, the ServiceRegistry implementation will auto-register the running service. To disable that behavior, there are two methods. You can set @EnableDiscoveryClient(autoRegister=false) to permanently disable auto-registration. You can also set spring.cloud.service-registry.auto-registration.enabled=false to disable the behavior via configuration.

3.2.2 Service Registry Actuator Endpoint

A /service-registry actuator endpoint is provided by Commons. This endpoint relys on a Registration bean in the Spring Application Context. Calling /service-registry/instance-status via a GET will return the status of the Registration. A POST to the same endpoint with a String body will change the status of the current Registration to the new value. Please see the documentation of the ServiceRegistry implementation you are using for the allowed values for updating the status and the values retured for the status.

3.3 Spring RestTemplate as a Load Balancer Client

RestTemplate can be automatically configured to use ribbon. To create a load balanced RestTemplate create a RestTemplate @Bean and use the @LoadBalanced qualifier.

[Warning]Warning

A RestTemplate bean is no longer created via auto configuration. It must be created by individual applications.

@Configuration
+public class MyConfiguration {
+
+    @LoadBalanced
+    @Bean
+    RestTemplate restTemplate() {
+        return new RestTemplate();
+    }
+}
+
+public class MyClass {
+    @Autowired
+    private RestTemplate restTemplate;
+
+    public String doOtherStuff() {
+        String results = restTemplate.getForObject("http://stores/stores", String.class);
+        return results;
+    }
+}

The URI needs to use a virtual host name (ie. service name, not a host name). +The Ribbon client is used to create a full physical address. See +RibbonAutoConfiguration +for details of how the RestTemplate is set up.

3.3.1 Retrying Failed Requests

A load balanced RestTemplate can be configured to retry failed requests. +By default this logic is disabled, you can enable it by adding Spring Retry to your application’s classpath. The load balanced RestTemplate will +honor some of the Ribbon configuration values related to retrying failed requests. If +you would like to disable the retry logic with Spring Retry on the classpath +you can set spring.cloud.loadbalancer.retry.enabled=false. +The properties you can use are client.ribbon.MaxAutoRetries, +client.ribbon.MaxAutoRetriesNextServer, and client.ribbon.OkToRetryOnAllOperations. +See the Ribbon documentation +for a description of what there properties do.

If you would like to implement a BackOffPolicy in your retries you will need to +create a bean of type LoadBalancedBackOffPolicyFactory, and return the BackOffPolicy +you would like to use for a given service.

@Configuration
+public class MyConfiguration {
+    @Bean
+    LoadBalancedBackOffPolicyFactory backOffPolciyFactory() {
+        return new LoadBalancedBackOffPolicyFactory() {
+            @Override
+            public BackOffPolicy createBackOffPolicy(String service) {
+        		return new ExponentialBackOffPolicy();
+        	}
+        };
+    }
+}
[Note]Note

client in the above examples should be replaced with your Ribbon client’s +name.

If you want to add one or more RetryListener to your retry you will need to +create a bean of type LoadBalancedRetryListenerFactory and return the RetryListener array +you would like to use for a given service.

@Configuration
+public class MyConfiguration {
+    @Bean
+    LoadBalancedRetryListenerFactory retryListenerFactory() {
+        return new LoadBalancedRetryListenerFactory() {
+            @Override
+            public RetryListener[] createRetryListeners(String service) {
+                return new RetryListener[]{new RetryListener() {
+                    @Override
+                    public <T, E extends Throwable> boolean open(RetryContext context, RetryCallback<T, E> callback) {
+                        //TODO Do you business...
+                        return true;
+                    }
+
+                    @Override
+                     public <T, E extends Throwable> void close(RetryContext context, RetryCallback<T, E> callback, Throwable throwable) {
+                        //TODO Do you business...
+                    }
+
+                    @Override
+                    public <T, E extends Throwable> void onError(RetryContext context, RetryCallback<T, E> callback, Throwable throwable) {
+                        //TODO Do you business...
+                    }
+                }};
+            }
+        };
+    }
+}

3.4 Multiple RestTemplate objects

If you want a RestTemplate that is not load balanced, create a RestTemplate +bean and inject it as normal. To access the load balanced RestTemplate use +the @LoadBalanced qualifier when you create your @Bean.

[Important]Important

Notice the @Primary annotation on the plain RestTemplate declaration in the example below, to disambiguate the unqualified @Autowired injection.

@Configuration
+public class MyConfiguration {
+
+    @LoadBalanced
+    @Bean
+    RestTemplate loadBalanced() {
+        return new RestTemplate();
+    }
+
+    @Primary
+    @Bean
+    RestTemplate restTemplate() {
+        return new RestTemplate();
+    }
+}
+
+public class MyClass {
+    @Autowired
+    private RestTemplate restTemplate;
+
+    @Autowired
+    @LoadBalanced
+    private RestTemplate loadBalanced;
+
+    public String doOtherStuff() {
+        return loadBalanced.getForObject("http://stores/stores", String.class);
+    }
+
+    public String doStuff() {
+        return restTemplate.getForObject("https://example.com", String.class);
+    }
+}
[Tip]Tip

If you see errors like java.lang.IllegalArgumentException: Can not set org.springframework.web.client.RestTemplate field com.my.app.Foo.restTemplate to com.sun.proxy.$Proxy89 try injecting RestOperations instead or setting spring.aop.proxyTargetClass=true.

3.5 Ignore Network Interfaces

Sometimes it is useful to ignore certain named network interfaces so they can be excluded from Service Discovery registration (eg. running in a Docker container). A list of regular expressions can be set that will cause the desired network interfaces to be ignored. The following configuration will ignore the "docker0" interface and all interfaces that start with "veth".

application.yml.  +

spring:
+  cloud:
+    inetutils:
+      ignoredInterfaces:
+        - docker0
+        - veth.*

+

You can also force to use only specified network addresses using list of regular expressions:

bootstrap.yml.  +

spring:
+  cloud:
+    inetutils:
+      preferredNetworks:
+        - 192.168
+        - 10.0

+

You can also force to use only site local addresses. See Inet4Address.html.isSiteLocalAddress() for more details what is site local address.

application.yml.  +

spring:
+  cloud:
+    inetutils:
+      useOnlySiteLocalInterfaces: true

+

3.6 HTTP Client Factories

Spring Cloud Commons provides beans for creating both Apache HTTP clients (ApacheHttpClientFactory) +as well as OK HTTP clients (OkHttpClientFactory). The OkHttpClientFactory bean will only be created +if the OK HTTP jar is on the classpath. In addition, Spring Cloud Commons provides beans for creating +the connection managers used by both clients, ApacheHttpClientConnectionManagerFactory for the Apache +HTTP client and OkHttpClientConnectionPoolFactory for the OK HTTP client. You can provide +your own implementation of these beans if you would like to customize how the HTTP clients are created +in downstream projects. You can also disable the creation of these beans by setting +spring.cloud.httpclientfactories.apache.enabled or spring.cloud.httpclientfactories.ok.enabled to +false.

3.7 Spring Cloud Compatibility Verification

Due to the fact that some users have problem with setting up Spring Cloud application, we’ve decided +to add a compatibility verification mechanism. It will break if your current setup is not compatible +with Spring Cloud requirements, together with a report, showing what exactly went wrong.

At the moment we verify which version of Spring Boot is added to your classpath.

Example of a report

***************************
+APPLICATION FAILED TO START
+***************************
+
+Description:
+
+Your project setup is incompatible with our requirements due to following reasons:
+
+- Spring Boot [1.5.16.RELEASE] is not compatible with this Spring Cloud release train
+
+
+Action:
+
+Consider applying the following actions:
+
+- Change Spring Boot version to one of the following versions [1.2.x, 1.3.x] .
+You can find the latest Spring Boot versions here [https://spring.io/projects/spring-boot#learn].
+If you want to learn more about the Spring Cloud Release train compatibility, you can visit this page [https://spring.io/projects/spring-cloud#overview] and check the [Release Trains] section.

In order to disable this feature, set spring.cloud.compatibility-verifier.enabled to false. +If you want to override the compatible Spring Boot versions, just set the +spring.cloud.compatibility-verifier.compatible-boot-versions property with a comma separated list +of compatible Spring Boot versions.

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2. Spring Cloud Context: Application Context Services Home Part II. Spring Cloud Config
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Part II. Spring Cloud Config
Prev   Next

Part II. Spring Cloud Config

1.3.8.RELEASE

Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With the Config Server you have a central place to manage external properties for applications across all environments. The concepts on both client and server map identically to the Spring Environment and PropertySource abstractions, so they fit very well with Spring applications, but can be used with any application running in any language. As an application moves through the deployment pipeline from dev to test and into production you can manage the configuration between those environments and be certain that applications have everything they need to run when they migrate. The default implementation of the server storage backend uses git so it easily supports labelled versions of configuration environments, as well as being accessible to a wide range of tooling for managing the content. It is easy to add alternative implementations and plug them in with Spring configuration.

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3. Spring Cloud Commons: Common Abstractions Home 4. Quick Start
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10. Spring Cloud Config Client
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10. Spring Cloud Config Client

A Spring Boot application can take immediate advantage of the Spring +Config Server (or other external property sources provided by the +application developer), and it will also pick up some additional +useful features related to Environment change events.

10.1 Config First Bootstrap

This is the default behaviour for any application which has the Spring +Cloud Config Client on the classpath. When a config client starts up +it binds to the Config Server (via the bootstrap configuration +property spring.cloud.config.uri) and initializes Spring +Environment with remote property sources.

The net result of this is that all client apps that want to consume +the Config Server need a bootstrap.yml (or an environment variable) +with the server address in spring.cloud.config.uri (defaults to +"http://localhost:8888").

10.2 Discovery First Bootstrap

If you are using a `DiscoveryClient implementation, such as Spring Cloud Netflix +and Eureka Service Discovery or Spring Cloud Consul (Spring Cloud Zookeeper does +not support this yet), then you can have the Config Server register with the +Discovery Service if you want to, but in the default "Config First" mode, +clients won’t be able to take advantage of the registration.

If you prefer to use DiscoveryClient to locate the Config Server, you can do +that by setting spring.cloud.config.discovery.enabled=true (default +"false"). The net result of that is that client apps all need a +bootstrap.yml (or an environment variable) with the appropriate discovery +configuration. For example, with Spring Cloud Netflix, you need to define the +Eureka server address, e.g. in eureka.client.serviceUrl.defaultZone. The +price for using this option is an extra network round trip on start up to +locate the service registration. The benefit is that the Config Server +can change its co-ordinates, as long as the Discovery Service is a fixed point. The +default service id is "configserver" but you can change that on the +client with spring.cloud.config.discovery.serviceId (and on the server +in the usual way for a service, e.g. by setting spring.application.name).

The discovery client implementations all support some kind of metadata +map (e.g. for Eureka we have eureka.instance.metadataMap). Some +additional properties of the Config Server may need to be configured +in its service registration metadata so that clients can connect +correctly. If the Config Server is secured with HTTP Basic you can +configure the credentials as "username" and "password". And if the +Config Server has a context path you can set "configPath". Example, +for a Config Server that is a Eureka client:

bootstrap.yml.  +

eureka:
+  instance:
+    ...
+    metadataMap:
+      user: osufhalskjrtl
+      password: lviuhlszvaorhvlo5847
+      configPath: /config

+

10.3 Config Client Fail Fast

In some cases, it may be desirable to fail startup of a service if +it cannot connect to the Config Server. If this is the desired +behavior, set the bootstrap configuration property +spring.cloud.config.failFast=true and the client will halt with +an Exception.

10.4 Config Client Retry

If you expect that the config server may occasionally be unavailable when +your app starts, you can ask it to keep trying after a failure. First you need +to set spring.cloud.config.failFast=true, and then you need to add +spring-retry and spring-boot-starter-aop to your classpath. The default +behaviour is to retry 6 times with an initial backoff interval of 1000ms and an +exponential multiplier of 1.1 for subsequent backoffs. You can configure these +properties (and others) using spring.cloud.config.retry.* configuration properties.

[Tip]Tip

To take full control of the retry add a @Bean of type +RetryOperationsInterceptor with id "configServerRetryInterceptor". Spring +Retry has a RetryInterceptorBuilder that makes it easy to create one.

10.5 Locating Remote Configuration Resources

The Config Service serves property sources from /{name}/{profile}/{label}, where the default bindings in the client app are

  • "name" = ${spring.application.name}
  • "profile" = ${spring.profiles.active} (actually Environment.getActiveProfiles())
  • "label" = "master"

All of them can be overridden by setting spring.cloud.config.* +(where * is "name", "profile" or "label"). The "label" is useful for +rolling back to previous versions of configuration; with the default +Config Server implementation it can be a git label, branch name or +commit id. Label can also be provided as a comma-separated list, in +which case the items in the list are tried on-by-one until one succeeds. +This can be useful when working on a feature branch, for instance, +when you might want to align the config label with your branch, but +make it optional (e.g. spring.cloud.config.label=myfeature,develop).

10.6 Security

If you use HTTP Basic security on the server then clients just need to +know the password (and username if it isn’t the default). You can do +that via the config server URI, or via separate username and password +properties, e.g.

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+     uri: https://user:secret@myconfig.mycompany.com

+

or

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+     uri: https://myconfig.mycompany.com
+     username: user
+     password: secret

+

The spring.cloud.config.password and spring.cloud.config.username +values override anything that is provided in the URI.

If you deploy your apps on Cloud Foundry then the best way to provide +the password is through service credentials, e.g. in the URI, since +then it doesn’t even need to be in a config file. An example which +works locally and for a user-provided service on Cloud Foundry named +"configserver":

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+     uri: ${vcap.services.configserver.credentials.uri:http://user:password@localhost:8888}

+

If you use another form of security you might need to provide a +RestTemplate to the ConfigServicePropertySourceLocator (e.g. by +grabbing it in the bootstrap context and injecting one).

10.6.1 Health Indicator

The Config Client supplies a Spring Boot Health Indicator that attempts to load configuration from Config Server. The health indicator can be disabled by setting health.config.enabled=false. The response is also cached for performance reasons. The default cache time to live is 5 minutes. To change that value set the health.config.time-to-live property (in milliseconds).

10.6.2 Providing A Custom RestTemplate

In some cases you might need to customize the requests made to the config server from +the client. Typically this involves passing special Authorization headers to +authenticate requests to the server. To provide a custom RestTemplate follow the +steps below.

  1. Create a new configuration bean with an implementation of PropertySourceLocator.

CustomConfigServiceBootstrapConfiguration.java.  +

@Configuration
+public class CustomConfigServiceBootstrapConfiguration {
+    @Bean
+    public ConfigServicePropertySourceLocator configServicePropertySourceLocator() {
+        ConfigClientProperties clientProperties = configClientProperties();
+       ConfigServicePropertySourceLocator configServicePropertySourceLocator =  new ConfigServicePropertySourceLocator(clientProperties);
+        configServicePropertySourceLocator.setRestTemplate(customRestTemplate(clientProperties));
+        return configServicePropertySourceLocator;
+    }
+}

+

  1. In resources/META-INF create a file called +spring.factories and specify your custom configuration.

spring.factories.  +

org.springframework.cloud.bootstrap.BootstrapConfiguration = com.my.config.client.CustomConfigServiceBootstrapConfiguration

+

10.6.3 Vault

When using Vault as a backend to your config server the client will need to +supply a token for the server to retrieve values from Vault. This token +can be provided within the client by setting spring.cloud.config.token +in bootstrap.yml.

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+      token: YourVaultToken

+

10.7 Vault

10.7.1 Nested Keys In Vault

Vault supports the ability to nest keys in a value stored in Vault. For example

echo -n '{"appA": {"secret": "appAsecret"}, "bar": "baz"}' | vault write secret/myapp -

This command will write a JSON object to your Vault. To access these values in Spring +you would use the traditional dot(.) annotation. For example

@Value("${appA.secret}")
+String name = "World";

The above code would set the name variable to appAsecret.

Prev Up Next
9. Push Notifications and Spring Cloud Bus Home Part III. Spring Cloud Netflix
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5. Spring Cloud Config Server
Prev Part II. Spring Cloud Config Next

5. Spring Cloud Config Server

The Server provides an HTTP, resource-based API for external +configuration (name-value pairs, or equivalent YAML content). The +server is easily embeddable in a Spring Boot application using the +@EnableConfigServer annotation. So this app is a config server:

ConfigServer.java.  +

@SpringBootApplication
+@EnableConfigServer
+public class ConfigServer {
+  public static void main(String[] args) {
+    SpringApplication.run(ConfigServer.class, args);
+  }
+}

+

Like all Spring Boot apps it runs on port 8080 by default, but you +can switch it to the conventional port 8888 in various ways. The +easiest, which also sets a default configuration repository, +is by launching it with spring.config.name=configserver (there +is a configserver.yml in the Config Server jar). Another is +to use your own application.properties, e.g.

application.properties.  +

server.port: 8888
+spring.cloud.config.server.git.uri: file://${user.home}/config-repo

+

where ${user.home}/config-repo is a git repository containing +YAML and properties files.

[Note]Note

in Windows you need an extra "/" in the file URL if it is +absolute with a drive prefix, e.g. file:///${user.home}/config-repo.

[Tip]Tip

Here’s a recipe for creating the git repository in the example +above:

$ cd $HOME
+$ mkdir config-repo
+$ cd config-repo
+$ git init .
+$ echo info.foo: bar > application.properties
+$ git add -A .
+$ git commit -m "Add application.properties"
[Warning]Warning

using the local filesystem for your git repository is +intended for testing only. Use a server to host your +configuration repositories in production.

[Warning]Warning

the initial clone of your configuration repository will +be quick and efficient if you only keep text files in it. If you start +to store binary files, especially large ones, you may experience +delays on the first request for configuration and/or out of memory +errors in the server.

5.1 Environment Repository

Where do you want to store the configuration data for the Config +Server? The strategy that governs this behaviour is the +EnvironmentRepository, serving Environment objects. This +Environment is a shallow copy of the domain from the Spring +Environment (including propertySources as the main feature). The +Environment resources are parametrized by three variables:

  • {application} maps to "spring.application.name" on the client side;
  • {profile} maps to "spring.profiles.active" on the client (comma separated list); and
  • {label} which is a server side feature labelling a "versioned" set of config files.

Repository implementations generally behave just like a Spring Boot +application loading configuration files from a "spring.config.name" +equal to the {application} parameter, and "spring.profiles.active" +equal to the {profiles} parameter. Precedence rules for profiles are +also the same as in a regular Boot application: active profiles take +precedence over defaults, and if there are multiple profiles the last +one wins (like adding entries to a Map).

Example: a client application has this bootstrap configuration:

bootstrap.yml.  +

spring:
+  application:
+    name: foo
+  profiles:
+    active: dev,mysql

+

(as usual with a Spring Boot application, these properties could also +be set as environment variables or command line arguments).

If the repository is file-based, the server will create an +Environment from application.yml (shared between all clients), and +foo.yml (with foo.yml taking precedence). If the YAML files have +documents inside them that point to Spring profiles, those are applied +with higher precedence (in order of the profiles listed), and if +there are profile-specific YAML (or properties) files these are also +applied with higher precedence than the defaults. Higher precedence +translates to a PropertySource listed earlier in the +Environment. (These are the same rules as apply in a standalone +Spring Boot application.)

5.1.1 Git Backend

The default implementation of EnvironmentRepository uses a Git +backend, which is very convenient for managing upgrades and physical +environments, and also for auditing changes. To change the location of +the repository you can set the "spring.cloud.config.server.git.uri" +configuration property in the Config Server (e.g. in +application.yml). If you set it with a file: prefix it should work +from a local repository so you can get started quickly and easily +without a server, but in that case the server operates directly on the +local repository without cloning it (it doesn’t matter if it’s not +bare because the Config Server never makes changes to the "remote" +repository). To scale the Config Server up and make it highly +available, you would need to have all instances of the server pointing +to the same repository, so only a shared file system would work. Even +in that case it is better to use the ssh: protocol for a shared +filesystem repository, so that the server can clone it and use a local +working copy as a cache.

This repository implementation maps the {label} parameter of the +HTTP resource to a git label (commit id, branch name or tag). If the +git branch or tag name contains a slash ("/") then the label in the +HTTP URL should be specified with the special string "(_)" instead (to +avoid ambiguity with other URL paths). For example, if the label is +foo/bar, replacing the slash would result in a label that looks like +foo(_)bar. The inclusion of the special string "(_)" can also be +applied to the {application} parameter. Be careful with the brackets +in the URL if you are using a command line client like curl (e.g. +escape them from the shell with quotes '').

Placeholders in Git URI

Spring Cloud Config Server supports a git repository URL with +placeholders for the {application} and {profile} (and {label} if +you need it, but remember that the label is applied as a git label +anyway). So you can easily support a "one repo per application" policy +using (for example):

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/myorg/{application}

or a "one repo per profile" policy using a similar pattern but with +{profile}.

Additionally, using the special string "(_)" within your +{application} parameters can enable support for multiple +organizations (for example):

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/{application}

where {application} is provided at request time in the format +"organization(_)application".

Pattern Matching and Multiple Repositories

There is also support for more complex requirements with pattern +matching on the application and profile name. The pattern format is a +comma-separated list of {application}/{profile} names with wildcards +(where a pattern beginning with a wildcard may need to be +quoted). Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          repos:
+            simple: https://github.com/simple/config-repo
+            special:
+              pattern: special*/dev*,*special*/dev*
+              uri: https://github.com/special/config-repo
+            local:
+              pattern: local*
+              uri: file:/home/configsvc/config-repo

If {application}/{profile} does not match any of the patterns, it +will use the default uri defined under +"spring.cloud.config.server.git.uri". In the above example, for the +"simple" repository, the pattern is simple/* (i.e. it only matches +one application named "simple" in all profiles). The "local" +repository matches all application names beginning with "local" in all +profiles (the /* suffix is added automatically to any pattern that +doesn’t have a profile matcher).

[Note]Note

the "one-liner" short cut used in the "simple" example above can +only be used if the only property to be set is the URI. If you need to +set anything else (credentials, pattern, etc.) you need to use the full +form.

The pattern property in the repo is actually an array, so you can +use a YAML array (or [0], [1], etc. suffixes in properties files) +to bind to multiple patterns. You may need to do this if you are going +to run apps with multiple profiles. Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          repos:
+            development:
+              pattern:
+                - '*/development'
+                - '*/staging'
+              uri: https://github.com/development/config-repo
+            staging:
+              pattern:
+                - '*/qa'
+                - '*/production'
+              uri: https://github.com/staging/config-repo
[Note]Note

Spring Cloud will guess that a pattern containing a profile that +doesn’t end in * implies that you actually want to match a list of +profiles starting with this pattern (so */staging is a shortcut for +["*/staging", "*/staging,*"]). This is common where you need to run +apps in the "development" profile locally but also the "cloud" profile +remotely, for instance.

Every repository can also optionally store config files in +sub-directories, and patterns to search for those directories can be +specified as searchPaths. For example at the top level:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          searchPaths: foo,bar*

In this example the server searches for config files in the top level +and in the "foo/" sub-directory and also any sub-directory whose name +begins with "bar".

By default the server clones remote repositories when configuration +is first requested. The server can be configured to clone the repositories +at startup. For example at the top level:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://git/common/config-repo.git
+          repos:
+            team-a:
+                pattern: team-a-*
+                cloneOnStart: true
+                uri: https://git/team-a/config-repo.git
+            team-b:
+                pattern: team-b-*
+                cloneOnStart: false
+                uri: https://git/team-b/config-repo.git
+            team-c:
+                pattern: team-c-*
+                uri: https://git/team-a/config-repo.git

In this example the server clones team-a’s config-repo on startup before it +accepts any requests. All other repositories will not be cloned until +configuration from the repository is requested.

[Note]Note

Setting a repository to be cloned when the Config Server starts up can +help to identify a misconfigured configuration source (e.g., an invalid +repository URI) quickly, while the Config Server is starting up. With +cloneOnStart not enabled for a configuration source, the Config Server may +start successfully with a misconfigured or invalid configuration source and +not detect an error until an application requests configuration from that +configuration source.

Authentication

To use HTTP basic authentication on the remote repository add the +"username" and "password" properties separately (not in the URL), +e.g.

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          username: trolley
+          password: strongpassword

If you don’t use HTTPS and user credentials, SSH should also work out +of the box when you store keys in the default directories (~/.ssh) +and the uri points to an SSH location, +e.g. "git@github.com:configuration/cloud-configuration". It is important that an entry for the Git server be present in the ~/.ssh/known_hosts file and that it is in ssh-rsa format. Other formats (like ecdsa-sha2-nistp256) are not supported. To avoid surprises, you should ensure that only one entry is present in the known_hosts file for the Git server and that it is matching with the URL you provided to the config server. If you used a hostname in the URL, you want to have exactly that in the known_hosts file, not the IP. +The repository is accessed using JGit, so any documentation you find on +that should be applicable. HTTPS proxy settings can be set in +~/.git/config or in the same way as for any other JVM process via +system properties (-Dhttps.proxyHost and -Dhttps.proxyPort).

[Tip]Tip

If you don’t know where your ~/.git directory is use git config +--global to manipulate the settings (e.g. git config --global +http.sslVerify false).

Authentication with AWS CodeCommit

AWS CodeCommit authentication can also be +done. AWS CodeCommit uses an authentication helper when using Git from the command line. This helper is not +used with the JGit library, so a JGit CredentialProvider for AWS CodeCommit will be created if the Git +URI matches the AWS CodeCommit pattern. AWS CodeCommit URIs always look like +https://git-codecommit.${AWS_REGION}.amazonaws.com/${repopath}.

If you provide a username and password with an AWS CodeCommit URI, then these must be +the AWS accessKeyId and secretAccessKey +to be used to access the repository. If you do not specify a username and password, +then the accessKeyId and secretAccessKey will be retrieved using the +AWS Default Credential Provider Chain.

If your Git URI matches the CodeCommit URI pattern (above) then you must provide +valid AWS credentials in the username and password, or in one of the locations supported +by the default credential provider chain. AWS EC2 instances may use +IAM Roles for EC2 Instances.

Note: The aws-java-sdk-core jar is an optional dependency. If the aws-java-sdk-core jar is not on your +classpath, then the AWS Code Commit credential provider will not be created regardless of the git server URI.

Git SSH configuration using properties

By default, the JGit library used by Spring Cloud Config Server uses SSH configuration files such as ~/.ssh/known_hosts and /etc/ssh/ssh_config when connecting to Git repositories using an SSH URI. +In cloud environments such as Cloud Foundry, the local filesystem may be ephemeral or not easily accessible. For cases such as these, SSH configuration can be set using +Java properties. In order to activate property based SSH configuration, the property spring.cloud.config.server.git.ignoreLocalSshSettings must be set to true. +Example:

  spring:
+    cloud:
+      config:
+        server:
+          git:
+            uri: git@gitserver.com:team/repo1.git
+            ignoreLocalSshSettings: true
+            hostKey: someHostKey
+            hostKeyAlgorithm: ssh-rsa
+            privateKey: |
+                         -----BEGIN RSA PRIVATE KEY-----
+                         MIIEpgIBAAKCAQEAx4UbaDzY5xjW6hc9jwN0mX33XpTDVW9WqHp5AKaRbtAC3DqX
+                         IXFMPgw3K45jxRb93f8tv9vL3rD9CUG1Gv4FM+o7ds7FRES5RTjv2RT/JVNJCoqF
+                         ol8+ngLqRZCyBtQN7zYByWMRirPGoDUqdPYrj2yq+ObBBNhg5N+hOwKjjpzdj2Ud
+                         1l7R+wxIqmJo1IYyy16xS8WsjyQuyC0lL456qkd5BDZ0Ag8j2X9H9D5220Ln7s9i
+                         oezTipXipS7p7Jekf3Ywx6abJwOmB0rX79dV4qiNcGgzATnG1PkXxqt76VhcGa0W
+                         DDVHEEYGbSQ6hIGSh0I7BQun0aLRZojfE3gqHQIDAQABAoIBAQCZmGrk8BK6tXCd
+                         fY6yTiKxFzwb38IQP0ojIUWNrq0+9Xt+NsypviLHkXfXXCKKU4zUHeIGVRq5MN9b
+                         BO56/RrcQHHOoJdUWuOV2qMqJvPUtC0CpGkD+valhfD75MxoXU7s3FK7yjxy3rsG
+                         EmfA6tHV8/4a5umo5TqSd2YTm5B19AhRqiuUVI1wTB41DjULUGiMYrnYrhzQlVvj
+                         5MjnKTlYu3V8PoYDfv1GmxPPh6vlpafXEeEYN8VB97e5x3DGHjZ5UrurAmTLTdO8
+                         +AahyoKsIY612TkkQthJlt7FJAwnCGMgY6podzzvzICLFmmTXYiZ/28I4BX/mOSe
+                         pZVnfRixAoGBAO6Uiwt40/PKs53mCEWngslSCsh9oGAaLTf/XdvMns5VmuyyAyKG
+                         ti8Ol5wqBMi4GIUzjbgUvSUt+IowIrG3f5tN85wpjQ1UGVcpTnl5Qo9xaS1PFScQ
+                         xrtWZ9eNj2TsIAMp/svJsyGG3OibxfnuAIpSXNQiJPwRlW3irzpGgVx/AoGBANYW
+                         dnhshUcEHMJi3aXwR12OTDnaLoanVGLwLnkqLSYUZA7ZegpKq90UAuBdcEfgdpyi
+                         PhKpeaeIiAaNnFo8m9aoTKr+7I6/uMTlwrVnfrsVTZv3orxjwQV20YIBCVRKD1uX
+                         VhE0ozPZxwwKSPAFocpyWpGHGreGF1AIYBE9UBtjAoGBAI8bfPgJpyFyMiGBjO6z
+                         FwlJc/xlFqDusrcHL7abW5qq0L4v3R+FrJw3ZYufzLTVcKfdj6GelwJJO+8wBm+R
+                         gTKYJItEhT48duLIfTDyIpHGVm9+I1MGhh5zKuCqIhxIYr9jHloBB7kRm0rPvYY4
+                         VAykcNgyDvtAVODP+4m6JvhjAoGBALbtTqErKN47V0+JJpapLnF0KxGrqeGIjIRV
+                         cYA6V4WYGr7NeIfesecfOC356PyhgPfpcVyEztwlvwTKb3RzIT1TZN8fH4YBr6Ee
+                         KTbTjefRFhVUjQqnucAvfGi29f+9oE3Ei9f7wA+H35ocF6JvTYUsHNMIO/3gZ38N
+                         CPjyCMa9AoGBAMhsITNe3QcbsXAbdUR00dDsIFVROzyFJ2m40i4KCRM35bC/BIBs
+                         q0TY3we+ERB40U8Z2BvU61QuwaunJ2+uGadHo58VSVdggqAo0BSkH58innKKt96J
+                         69pcVH/4rmLbXdcmNYGm6iu+MlPQk4BUZknHSmVHIFdJ0EPupVaQ8RHT
+                         -----END RSA PRIVATE KEY-----

Table 5.1. SSH Configuration properties

Property NameRemarks

ignoreLocalSshSettings

If true, use property based SSH config instead of file based. Must be set at as spring.cloud.config.server.git.ignoreLocalSshSettings, not inside a repository definition.

privateKey

Valid SSH private key. Must be set if ignoreLocalSshSettings is true and Git URI is SSH format

hostKey

Valid SSH host key. Must be set if hostKeyAlgorithm is also set

hostKeyAlgorithm

One of ssh-dss, ssh-rsa, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384 ,ecdsa-sha2-nistp521. Must be set if hostKey is also set

proxyHost

Hostname for the ssh proxy connection. Is optional and used only when ignoreLocalSshSettings is true

proxyPort

Port for the ssh proxy connection. Must be set if proxyHost is also set

strictHostKeyChecking

true or false. If false, ignore errors with host key

knownHostsFile

Location of custom .known_hosts file

preferredAuthentications

Override server authentication method order. This should allow evade login prompts if server has keyboard-interactive authentication before publickey method.


Placeholders in Git Search Paths

Spring Cloud Config Server also supports a search path with +placeholders for the {application} and {profile} (and {label} if +you need it). Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          searchPaths: '{application}'

searches the repository for files in the same name as the directory +(as well as the top level). Wildcards are also valid in a search +path with placeholders (any matching directory is included in the +search).

Force pull in Git Repositories

As mentioned before Spring Cloud Config Server makes a clone of the +remote git repository and if somehow the local copy gets dirty (e.g. +folder content changes by OS process) so Spring Cloud Config Server +cannot update the local copy from remote repository.

To solve this there is a force-pull property that will make Spring Cloud +Config Server force pull from remote repository if the local copy is dirty. +Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          force-pull: true

If you have a multiple repositories configuration you can configure the +force-pull property per repository. Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://git/common/config-repo.git
+          force-pull: true
+          repos:
+            team-a:
+                pattern: team-a-*
+                uri: https://git/team-a/config-repo.git
+                force-pull: true
+            team-b:
+                pattern: team-b-*
+                uri: https://git/team-b/config-repo.git
+                force-pull: true
+            team-c:
+                pattern: team-c-*
+                uri: https://git/team-a/config-repo.git
[Note]Note

The default value for force-pull property is false.

Deleting untracked branches in Git Repositories

As Spring Cloud Config Server has a clone of the remote git repository +after check-outing branch to local repo (e.g fetching properties by label) it will keep this branch +forever or till the next server restart (which creates new local repo). +So there could be a case when remote branch is deleted but local copy of it is still available for fetching. +And if Spring Cloud Config Server client service starts with --spring.cloud.config.label=deletedRemoteBranch,master +it will fetch properties from deletedRemoteBranch local branch, but not from master.

In order to keep local repository branches clean and up to remote - deleteUntrackedBranches property could be set. +It will make Spring Cloud Config Server force delete untracked branches from local repository. +Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          deleteUntrackedBranches: true
[Note]Note

The default value for deleteUntrackedBranches property is false.

5.1.2 Version Control Backend Filesystem Use

[Warning]Warning

With VCS based backends (git, svn) files are checked out or cloned to the local filesystem. By default they are put in the system temporary directory with a prefix of config-repo-. On linux, for example it could be /tmp/config-repo-<randomid>. Some operating systems routinely clean out temporary directories. This can lead to unexpected behaviour such as missing properties. To avoid this problem, change the directory Config Server uses, by setting spring.cloud.config.server.git.basedir or spring.cloud.config.server.svn.basedir to a directory that does not reside in the system temp structure.

5.1.3 File System Backend

There is also a "native" profile in the Config Server that doesn’t use +Git, but just loads the config files from the local classpath or file +system (any static URL you want to point to with +"spring.cloud.config.server.native.searchLocations"). To use the +native profile just launch the Config Server with +"spring.profiles.active=native".

[Note]Note

Remember to use the file: prefix for file resources (the +default without a prefix is usually the classpath). Just as with any +Spring Boot configuration you can embed ${}-style environment +placeholders, but remember that absolute paths in Windows require an +extra "/", e.g. file:///${user.home}/config-repo

[Warning]Warning

The default value of the searchLocations is identical to a +local Spring Boot application (so [classpath:/, classpath:/config, +file:./, file:./config]). This does not expose the +application.properties from the server to all clients because any +property sources present in the server are removed before being sent +to the client.

[Tip]Tip

A filesystem backend is great for getting started quickly and +for testing. To use it in production you need to be sure that the +file system is reliable, and shared across all instances of the +Config Server.

The search locations can contain placeholders for {application}, +{profile} and {label}. In this way you can segregate the +directories in the path, and choose a strategy that makes sense for +you (e.g. sub-directory per application, or sub-directory per +profile).

If you don’t use placeholders in the search locations, this repository +also appends the {label} parameter of the HTTP resource to a suffix +on the search path, so properties files are loaded from each search +location and a subdirectory with the same name as the label (the +labelled properties take precedence in the Spring Environment). Thus +the default behaviour with no placeholders is the same as adding a +search location ending with /{label}/. For example file:/tmp/config +is the same as file:/tmp/config,file:/tmp/config/{label}. This behavior can be +disabled by setting spring.cloud.config.server.native.addLabelLocations=false.

5.1.4 Vault Backend

Spring Cloud Config Server also supports Vault as a backend.

Vault is a tool for securely accessing secrets. A secret is anything +that you want to tightly control access to, such as API keys, passwords, +certificates, and more. Vault provides a unified interface to any secret, +while providing tight access control and recording a detailed audit log.

For more information on Vault see the Vault quickstart guide.

To enable the config server to use a Vault backend you can run your config server +with the vault profile. For example in your config server’s application.properties +you can add spring.profiles.active=vault.

By default the config server will assume your Vault server is running at +http://127.0.0.1:8200. It also will assume that the name of backend +is secret and the key is application. All of these defaults can be +configured in your config server’s application.properties. Below is a +table of configurable Vault properties. All properties are prefixed with +spring.cloud.config.server.vault.

NameDefault Value

host

127.0.0.1

port

8200

scheme

http

backend

secret

defaultKey

application

profileSeparator

,

All configurable properties can be found in +org.springframework.cloud.config.server.environment.VaultEnvironmentRepository.

With your config server running you can make HTTP requests to the server to retrieve +values from the Vault backend. To do this you will need a token for your Vault server.

First place some data in you Vault. For example

$ vault write secret/application foo=bar baz=bam
+$ vault write secret/myapp foo=myappsbar

Now make the HTTP request to your config server to retrieve the values.

$ curl -X "GET" "http://localhost:8888/myapp/default" -H "X-Config-Token: yourtoken"

You should see a response similar to this after making the above request.

{
+   "name":"myapp",
+   "profiles":[
+      "default"
+   ],
+   "label":null,
+   "version":null,
+   "state":null,
+   "propertySources":[
+      {
+         "name":"vault:myapp",
+         "source":{
+            "foo":"myappsbar"
+         }
+      },
+      {
+         "name":"vault:application",
+         "source":{
+            "baz":"bam",
+            "foo":"bar"
+         }
+      }
+   ]
+}

Multiple Properties Sources

When using Vault you can provide your applications with multiple properties sources. +For example, assume you have written data to the following paths in Vault.

secret/myApp,dev
+secret/myApp
+secret/application,dev
+secret/application

Properties written to secret/application are available to +all applications using the Config Server. An +application with the name myApp would have any properties +written to secret/myApp and secret/application available to it. +When myApp has the dev profile enabled then properties written to +all of the above paths would be available to it, with properties in +the first path in the list taking priority over the others.

5.1.5 Sharing Configuration With All Applications

File Based Repositories

With file-based (i.e. git, svn and native) repositories, resources +with file names in application* are shared between all client +applications (so application.properties, application.yml, +application-*.properties etc.). You can use resources with these +file names to configure global defaults and have them overridden by +application-specific files as necessary.

The #_property_overrides[property overrides] feature can also be used +for setting global defaults, and with placeholders applications are +allowed to override them locally.

[Tip]Tip

With the "native" profile (local file system backend) it is +recommended that you use an explicit search location that isn’t part +of the server’s own configuration. Otherwise the application* +resources in the default search locations are removed because they are +part of the server.

Vault Server

When using Vault as a backend you can share configuration with +all applications by placing configuration in +secret/application. For example, if you run this Vault command

$ vault write secret/application foo=bar baz=bam

All applications using the config server will have the properties +foo and baz available to them.

5.1.6 JDBC Backend

Spring Cloud Config Server supports JDBC (relation database) as a +backend for configuration properties. You can enable this feature by +adding spring-jdbc to the classpath, and using the "jdbc" profile, +or by adding a bean of type JdbcEnvironmentRepository. Spring Boot +will configure a data source if you include the right dependencies on +the classpath (see the user guide for more details on that).

The database needs to have a table called "PROPERTIES" with columns +"APPLICATION", "PROFILE", "LABEL" (with the usual Environment +meaning), plus "KEY" and "VALUE" for the key and value pairs in +Properties style. All fields are of type String in Java, so you can +make them VARCHAR of whatever length you need. Property values +behave in the same way as they would if they came from Spring Boot +properties files named {application}-{profile}.properties, including +all the encryption and decryption, which will be applied as +post-processing steps (i.e. not in the repository implementation +directly).

5.1.7 Composite Environment Repositories

In some scenarios you may wish to pull configuration data from multiple +environment repositories. To do this you can just enable +multiple profiles in your config server’s application properties or YAML file. +If, for example, you want to pull configuration data from a Git repository +as well as a SVN repository you would set the following properties for your +configuration server.

spring:
+  profiles:
+    active: git, svn
+  cloud:
+    config:
+      server:
+        svn:
+          uri: file:///path/to/svn/repo
+          order: 2
+        git:
+          uri: file:///path/to/git/repo
+          order: 1

In addition to each repo specifying a URI, you can also specify an order property. +The order property allows you to specify the priority order for all your repositories. +The lower the numerical value of the order property the higher priority it will have. +The priority order of a repository will help resolve any potential conflicts between +repositories that contain values for the same properties.

[Note]Note

Any type of failure when retrieving values from an environment repositoy +will result in a failure for the entire composite environment.

[Note]Note

When using a composite environment it is important that all repos contain +the same label(s). If you have an environment similar to the one above and you request +configuration data with the label master but the SVN +repo does not contain a branch called master the entire request will fail.

Custom Composite Environment Repositories

It is also possible to provide your own EnvironmentRepository bean +to be included as part of a composite environment in addition to +using one of the environment repositories from Spring Cloud. To do this your bean +must implement the EnvironmentRepository interface. If you would like to control +the priority of you custom EnvironmentRepository within the composite +environment you should also implement the Ordered interface and override the +getOrdered method. If you do not implement the Ordered interface then your +EnvironmentRepository will be given the lowest priority.

5.1.8 Property Overrides

The Config Server has an "overrides" feature that allows the operator +to provide configuration properties to all applications that cannot be +accidentally changed by the application using the normal Spring Boot +hooks. To declare overrides just add a map of name-value pairs to +spring.cloud.config.server.overrides. For example

spring:
+  cloud:
+    config:
+      server:
+        overrides:
+          foo: bar

will cause all applications that are config clients to read foo=bar +independent of their own configuration. (Of course an application can +use the data in the Config Server in any way it likes, so overrides +are not enforceable, but they do provide useful default behaviour if +they are Spring Cloud Config clients.)

[Tip]Tip

Normal, Spring environment placeholders with "${}" can be escaped +(and resolved on the client) by using backslash ("\") to escape the +"$" or the "{", e.g. \${app.foo:bar} resolves to "bar" unless the +app provides its own "app.foo". Note that in YAML you don’t need to +escape the backslash itself, but in properties files you do, when you +configure the overrides on the server.

You can change the priority of all overrides in the client to be more +like default values, allowing applications to supply their own values +in environment variables or System properties, by setting the flag +spring.cloud.config.overrideNone=true (default is false) in the +remote repository.

5.2 Health Indicator

Config Server comes with a Health Indicator that checks if the configured +EnvironmentRepository is working. By default it asks the EnvironmentRepository +for an application named app, the default profile and the default +label provided by the EnvironmentRepository implementation.

You can configure the Health Indicator to check more applications +along with custom profiles and custom labels, e.g.

spring:
+  cloud:
+    config:
+      server:
+        health:
+          repositories:
+            myservice:
+              label: mylabel
+            myservice-dev:
+              name: myservice
+              profiles: development

You can disable the Health Indicator by setting spring.cloud.config.server.health.enabled=false.

5.3 Security

You are free to secure your Config Server in any way that makes sense +to you (from physical network security to OAuth2 bearer +tokens), and Spring Security and Spring Boot make it easy to do pretty +much anything.

To use the default Spring Boot configured HTTP Basic security, just +include Spring Security on the classpath (e.g. through +spring-boot-starter-security). The default is a username of "user" +and a randomly generated password, which isn’t going to be very useful +in practice, so we recommend you configure the password (via +security.user.password) and encrypt it (see below for instructions +on how to do that).

5.4 Encryption and Decryption

[Important]Important

Prerequisites: to use the encryption and decryption features +you need the full-strength JCE installed in your JVM (it’s not there by default). +You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" +from Oracle, and follow instructions for installation (essentially replace the 2 policy files +in the JRE lib/security directory with the ones that you downloaded).

If the remote property sources contain encrypted content (values +starting with {cipher}) they will be decrypted before sending to +clients over HTTP. The main advantage of this set up is that the +property values don’t have to be in plain text when they are "at rest" +(e.g. in a git repository). If a value cannot be decrypted it is +removed from the property source and an additional property is added +with the same key, but prefixed with "invalid." and a value that means +"not applicable" (usually "<n/a>"). This is largely to prevent cipher +text being used as a password and accidentally leaking.

If you are setting up a remote config repository for config client +applications it might contain an application.yml like this, for +instance:

application.yml.  +

spring:
+  datasource:
+    username: dbuser
+    password: '{cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ'

+

Encrypted values in a .properties file must not be wrapped in quotes, otherwise the value will not be decrypted:

application.properties.  +

spring.datasource.username: dbuser
+spring.datasource.password: {cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ

+

You can safely push this plain text to a shared git repository and the +secret password is protected.

The server also exposes /encrypt and /decrypt endpoints (on the +assumption that these will be secured and only accessed by authorized +agents). If you are editing a remote config file you can use the Config Server +to encrypt values by POSTing to the /encrypt endpoint, e.g.

$ curl localhost:8888/encrypt -d mysecret
+682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
[Note]Note

If the value you are encrypting has characters in it that need to be URL encoded you should use +the --data-urlencode option to curl to make sure they are encoded properly.

[Tip]Tip

Be sure not to include any of the curl command statistics in the encrypted value. +Outputting the value to a file can help avoid this problem.

The inverse operation is also available via /decrypt (provided the server is +configured with a symmetric key or a full key pair):

$ curl localhost:8888/decrypt -d 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+mysecret
[Tip]Tip

If you are testing like this with curl, then use +--data-urlencode (instead of -d) or set an explicit Content-Type: +text/plain to make sure curl encodes the data correctly when there +are special characters ('+' is particularly tricky).

Take the encrypted value and add the {cipher} prefix before you put +it in the YAML or properties file, and before you commit and push it +to a remote, potentially insecure store.

The /encrypt and /decrypt endpoints also both accept paths of the +form /*/{name}/{profiles} which can be used to control cryptography +per application (name) and profile when clients call into the main +Environment resource.

[Note]Note

to control the cryptography in this granular way you must also +provide a @Bean of type TextEncryptorLocator that creates a +different encryptor per name and profiles. The one that is provided +by default does not do this (so all encryptions use the same key).

The spring command line client (with Spring Cloud CLI extensions +installed) can also be used to encrypt and decrypt, e.g.

$ spring encrypt mysecret --key foo
+682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+$ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+mysecret

To use a key in a file (e.g. an RSA public key for encryption) prepend +the key value with "@" and provide the file path, e.g.

$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub
+AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+...

The key argument is mandatory (despite having a -- prefix).

5.5 Key Management

The Config Server can use a symmetric (shared) key or an asymmetric +one (RSA key pair). The asymmetric choice is superior in terms of +security, but it is often more convenient to use a symmetric key since +it is just a single property value to configure in the bootstrap.properties.

To configure a symmetric key you just need to set encrypt.key to a +secret String (or use an enviroment variable ENCRYPT_KEY to keep it +out of plain text configuration files).

[Note]Note

You cannot configure an asymmetric key using encrypt.key.

To configure an asymmetric key use a keystore (e.g. as +created by the keytool utility that comes with the JDK). The +keystore properties are encrypt.keyStore.* with * equal to

  • location (a Resource location),
  • password (to unlock the keystore) and
  • alias (to identify which key in the store is to be +used).

The encryption is done with the public key, and a private key is +needed for decryption. Thus in principle you can configure only the +public key in the server if you only want to do encryption (and are +prepared to decrypt the values yourself locally with the private +key). In practice you might not want to do that because it spreads the +key management process around all the clients, instead of +concentrating it in the server. On the other hand it’s a useful option +if your config server really is relatively insecure and only a +handful of clients need the encrypted properties.

5.6 Creating a Key Store for Testing

To create a keystore for testing you can do something like this:

$ keytool -genkeypair -alias mytestkey -keyalg RSA \
+  -dname "CN=Web Server,OU=Unit,O=Organization,L=City,S=State,C=US" \
+  -keypass changeme -keystore server.jks -storepass letmein

Put the server.jks file in the classpath (for instance) and then in +your bootstrap.yml for the Config Server:

encrypt:
+  keyStore:
+    location: classpath:/server.jks
+    password: letmein
+    alias: mytestkey
+    secret: changeme

5.7 Using Multiple Keys and Key Rotation

In addition to the {cipher} prefix in encrypted property values, the +Config Server looks for {name:value} prefixes (zero or many) before +the start of the (Base64 encoded) cipher text. The keys are passed to +a TextEncryptorLocator which can do whatever logic it needs to +locate a TextEncryptor for the cipher. If you have configured a +keystore (encrypt.keystore.location) the default locator will look +for keys in the store with aliases as supplied by the "key" prefix, +i.e. with a cipher text like this:

foo:
+  bar: `{cipher}{key:testkey}...`

the locator will look for a key named "testkey". A secret can also be +supplied via a {secret:…​} value in the prefix, but if it is not +the default is to use the keystore password (which is what you get +when you build a keytore and don’t specify a secret). If you do +supply a secret it is recommended that you also encrypt the secrets +using a custom SecretLocator.

Key rotation is hardly ever necessary on cryptographic grounds if the +keys are only being used to encrypt a few bytes of configuration data +(i.e. they are not being used elsewhere), but occasionally you might +need to change the keys if there is a security breach for instance. In +that case all the clients would need to change their source config +files (e.g. in git) and use a new {key:…​} prefix in all the +ciphers, checking beforehand of course that the key alias is available +in the Config Server keystore.

[Tip]Tip

the {name:value} prefixes can also be added to plaintext posted +to the /encrypt endpoint, if you want to let the Config Server +handle all encryption as well as decryption.

5.8 Serving Encrypted Properties

Sometimes you want the clients to decrypt the configuration locally, +instead of doing it in the server. In that case you can still have +/encrypt and /decrypt endpoints (if you provide the encrypt.* +configuration to locate a key), but you need to explicitly switch off +the decryption of outgoing properties by placing +spring.cloud.config.server.encrypt.enabled=false in bootstrap.[yml|properties]. +If you don’t care about the endpoints, then it should work if you configure neither the +key nor the enabled flag.

Prev Up Next
4. Quick Start Home 6. Serving Alternative Formats
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Part VIII. Spring Cloud Consul
Prev   Next

Part VIII. Spring Cloud Consul

1.3.8.RELEASE

This project provides Consul integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with Consul based components. The +patterns provided include Service Discovery, Control Bus and Configuration. +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker +(Hystrix) are provided by integration with Spring Cloud Netflix.

Prev   Next
59. Running examples Home 60. Install Consul
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2. Spring Cloud Context: Application Context Services
Prev Part I. Cloud Native Applications Next

2. Spring Cloud Context: Application Context Services

Spring Boot has an opinionated view of how to build an application +with Spring: for instance it has conventional locations for common +configuration file, and endpoints for common management and monitoring +tasks. Spring Cloud builds on top of that and adds a few features that +probably all components in a system would use or occasionally need.

2.1 The Bootstrap Application Context

A Spring Cloud application operates by creating a "bootstrap" +context, which is a parent context for the main application. Out of +the box it is responsible for loading configuration properties from +the external sources, and also decrypting properties in the local +external configuration files. The two contexts share an Environment +which is the source of external properties for any Spring +application. Bootstrap properties (not bootstrap.properties but properties + that are loaded during the bootstrap phase) are added with high precedence, so +they cannot be overridden by local configuration, by default.

The bootstrap context uses a different convention for locating +external configuration than the main application context, so instead +of application.yml (or .properties) you use bootstrap.yml, +keeping the external configuration for bootstrap and main context +nicely separate. Example:

bootstrap.yml.  +

spring:
+  application:
+    name: foo
+  cloud:
+    config:
+      uri: ${SPRING_CONFIG_URI:http://localhost:8888}

+

It is a good idea to set the spring.application.name (in +bootstrap.yml or application.yml) if your application needs any +application-specific configuration from the server.

You can disable the bootstrap process completely by setting +spring.cloud.bootstrap.enabled=false (e.g. in System properties).

2.2 Application Context Hierarchies

If you build an application context from SpringApplication or +SpringApplicationBuilder, then the Bootstrap context is added as a +parent to that context. It is a feature of Spring that child contexts +inherit property sources and profiles from their parent, so the "main" +application context will contain additional property sources, compared +to building the same context without Spring Cloud Config. The +additional property sources are:

  • "bootstrap": an optional CompositePropertySource appears with high +priority if any PropertySourceLocators are found in the Bootstrap +context, and they have non-empty properties. An example would be +properties from the Spring Cloud Config Server. See +below for instructions +on how to customize the contents of this property source.
  • "applicationConfig: [classpath:bootstrap.yml]" (and friends if +Spring profiles are active). If you have a bootstrap.yml (or +properties) then those properties are used to configure the Bootstrap +context, and then they get added to the child context when its parent +is set. They have lower precedence than the application.yml (or +properties) and any other property sources that are added to the child +as a normal part of the process of creating a Spring Boot +application. See below for +instructions on how to customize the contents of these property +sources.

Because of the ordering rules of property sources the "bootstrap" +entries take precedence, but note that these do not contain any data +from bootstrap.yml, which has very low precedence, but can be used +to set defaults.

You can extend the context hierarchy by simply setting the parent +context of any ApplicationContext you create, e.g. using its own +interface, or with the SpringApplicationBuilder convenience methods +(parent(), child() and sibling()). The bootstrap context will be +the parent of the most senior ancestor that you create yourself. +Every context in the hierarchy will have its own "bootstrap" property +source (possibly empty) to avoid promoting values inadvertently from +parents down to their descendants. Every context in the hierarchy can +also (in principle) have a different spring.application.name and +hence a different remote property source if there is a Config +Server. Normal Spring application context behaviour rules apply to +property resolution: properties from a child context override those in +the parent, by name and also by property source name (if the child has +a property source with the same name as the parent, the one from the +parent is not included in the child).

Note that the SpringApplicationBuilder allows you to share an +Environment amongst the whole hierarchy, but that is not the +default. Thus, sibling contexts in particular do not need to have the +same profiles or property sources, even though they will share common +things with their parent.

2.3 Changing the Location of Bootstrap Properties

The bootstrap.yml (or .properties) location can be specified using +spring.cloud.bootstrap.name (default "bootstrap") or +spring.cloud.bootstrap.location (default empty), e.g. in System +properties. Those properties behave like the spring.config.* +variants with the same name, in fact they are used to set up the +bootstrap ApplicationContext by setting those properties in its +Environment. If there is an active profile (from +spring.profiles.active or through the Environment API in the +context you are building) then properties in that profile will be +loaded as well, just like in a regular Spring Boot app, e.g. from +bootstrap-development.properties for a "development" profile.

2.4 Overriding the Values of Remote Properties

The property sources that are added to you application by the +bootstrap context are often "remote" (e.g. from a Config Server), and +by default they cannot be overridden locally, except on the command +line. If you want to allow your applications to override the remote +properties with their own System properties or config files, the +remote property source has to grant it permission by setting +spring.cloud.config.allowOverride=true (it doesn’t work to set this +locally). Once that flag is set there are some finer grained settings +to control the location of the remote properties in relation to System +properties and the application’s local configuration: +spring.cloud.config.overrideNone=true to override with any local +property source, and +spring.cloud.config.overrideSystemProperties=false if only System +properties and env vars should override the remote settings, but not +the local config files.

2.5 Customizing the Bootstrap Configuration

The bootstrap context can be trained to do anything you like by adding +entries to /META-INF/spring.factories under the key +org.springframework.cloud.bootstrap.BootstrapConfiguration. This is +a comma-separated list of Spring @Configuration classes which will +be used to create the context. Any beans that you want to be available +to the main application context for autowiring can be created here, +and also there is a special contract for @Beans of type +ApplicationContextInitializer. Classes can be marked with an @Order +if you want to control the startup sequence (the default order is +"last").

[Warning]Warning

Be careful when adding custom BootstrapConfiguration that the +classes you add are not @ComponentScanned by mistake into your +"main" application context, where they might not be needed. +Use a separate package name for boot configuration classes that is +not already covered by your @ComponentScan or @SpringBootApplication +annotated configuration classes.

The bootstrap process ends by injecting initializers into the main +SpringApplication instance (i.e. the normal Spring Boot startup +sequence, whether it is running as a standalone app or deployed in an +application server). First a bootstrap context is created from the +classes found in spring.factories and then all @Beans of type +ApplicationContextInitializer are added to the main +SpringApplication before it is started.

2.6 Customizing the Bootstrap Property Sources

The default property source for external configuration added by the +bootstrap process is the Config Server, but you can add additional +sources by adding beans of type PropertySourceLocator to the +bootstrap context (via spring.factories). You could use this to +insert additional properties from a different server, or from a +database, for instance.

As an example, consider the following trivial custom locator:

@Configuration
+public class CustomPropertySourceLocator implements PropertySourceLocator {
+
+    @Override
+    public PropertySource<?> locate(Environment environment) {
+        return new MapPropertySource("customProperty",
+                Collections.<String, Object>singletonMap("property.from.sample.custom.source", "worked as intended"));
+    }
+
+}

The Environment that is passed in is the one for the +ApplicationContext about to be created, i.e. the one that we are +supplying additional property sources for. It will already have its +normal Spring Boot-provided property sources, so you can use those to +locate a property source specific to this Environment (e.g. by +keying it on the spring.application.name, as is done in the default +Config Server property source locator).

If you create a jar with this class in it and then add a +META-INF/spring.factories containing:

org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator

then the "customProperty" PropertySource will show up in any +application that includes that jar on its classpath.

2.7 Logging Configuration

If you are going to use Spring Boot to configure log settings than +you should place this configuration in `bootstrap.[yml | properties] +if you would like it to apply to all events.

2.8 Environment Changes

The application will listen for an EnvironmentChangeEvent and react +to the change in a couple of standard ways (additional +ApplicationListeners can be added as @Beans by the user in the +normal way). When an EnvironmentChangeEvent is observed it will +have a list of key values that have changed, and the application will +use those to:

  • Re-bind any @ConfigurationProperties beans in the context
  • Set the logger levels for any properties in logging.level.*

Note that the Config Client does not by default poll for changes in +the Environment, and generally we would not recommend that approach +for detecting changes (although you could set it up with a +@Scheduled annotation). If you have a scaled-out client application +then it is better to broadcast the EnvironmentChangeEvent to all +the instances instead of having them polling for changes (e.g. using +the Spring Cloud +Bus).

The EnvironmentChangeEvent covers a large class of refresh use +cases, as long as you can actually make a change to the Environment +and publish the event (those APIs are public and part of core +Spring). You can verify the changes are bound to +@ConfigurationProperties beans by visiting the /configprops +endpoint (normal Spring Boot Actuator feature). For instance a +DataSource can have its maxPoolSize changed at runtime (the +default DataSource created by Spring Boot is an +@ConfigurationProperties bean) and grow capacity +dynamically. Re-binding @ConfigurationProperties does not cover +another large class of use cases, where you need more control over the +refresh, and where you need a change to be atomic over the whole +ApplicationContext. To address those concerns we have +@RefreshScope.

2.9 Refresh Scope

A Spring @Bean that is marked as @RefreshScope will get special +treatment when there is a configuration change. This addresses the +problem of stateful beans that only get their configuration injected +when they are initialized. For instance if a DataSource has open +connections when the database URL is changed via the Environment, we +probably want the holders of those connections to be able to complete +what they are doing. Then the next time someone borrows a connection +from the pool he gets one with the new URL.

Refresh scope beans are lazy proxies that initialize when they are +used (i.e. when a method is called), and the scope acts as a cache of +initialized values. To force a bean to re-initialize on the next +method call you just need to invalidate its cache entry.

The RefreshScope is a bean in the context and it has a public method +refreshAll() to refresh all beans in the scope by clearing the +target cache. There is also a refresh(String) method to refresh an +individual bean by name. This functionality is exposed in the +/refresh endpoint (over HTTP or JMX).

[Note]Note

@RefreshScope works (technically) on an @Configuration +class, but it might lead to surprising behaviour: e.g. it does not +mean that all the @Beans defined in that class are themselves +@RefreshScope. Specifically, anything that depends on those beans +cannot rely on them being updated when a refresh is initiated, unless +it is itself in @RefreshScope (in which it will be rebuilt on a +refresh and its dependencies re-injected, at which point they will be +re-initialized from the refreshed @Configuration).

2.10 Encryption and Decryption

Spring Cloud has an Environment pre-processor for decrypting +property values locally. It follows the same rules as the Config +Server, and has the same external configuration via encrypt.*. Thus +you can use encrypted values in the form {cipher}* and as long as +there is a valid key then they will be decrypted before the main +application context gets the Environment. To use the encryption +features in an application you need to include Spring Security RSA in +your classpath (Maven co-ordinates +"org.springframework.security:spring-security-rsa") and you also need +the full strength JCE extensions in your JVM.

If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:

Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).

2.11 Endpoints

For a Spring Boot Actuator application there are some additional management endpoints:

  • POST to /env to update the Environment and rebind @ConfigurationProperties and log levels
  • /refresh for re-loading the boot strap context and refreshing the @RefreshScope beans
  • /restart for closing the ApplicationContext and restarting it (disabled by default)
  • /pause and /resume for calling the Lifecycle methods (stop() and start() on the ApplicationContext)
[Note]Note

If you disable the /restart endpoint then the /pause and /resume endpoints +will also be disabled since they are just a special case of /restart.

Prev Up Next
Part I. Cloud Native Applications Home 3. Spring Cloud Commons: Common Abstractions
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Part XIII. Spring Cloud Contract
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Part XIII. Spring Cloud Contract

_Documentation Authors: Adam Dudczak, Mathias Düsterhöft, Marcin Grzejszczak, Dennis Kieselhorst, Jakub Kubryński, Karol Lassak, +Olga Maciaszek-Sharma, Mariusz Smykuła, Dave Syer, Jay Bryant

1.3.8.RELEASE

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83. Single Sign On Home 84. Spring Cloud Contract
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84. Spring Cloud Contract
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84. Spring Cloud Contract

You need confidence when pushing new features to a new application or service in a +distributed system. This project provides support for Consumer Driven Contracts and +service schemas in Spring applications (for both HTTP and message-based interactions), +covering a range of options for writing tests, publishing them as assets, and asserting +that a contract is kept by producers and consumers.

Prev Up Next
Part XIII. Spring Cloud Contract Home 85. Spring Cloud Contract Verifier Introduction
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86. Spring Cloud Contract FAQ
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86. Spring Cloud Contract FAQ

86.1 Why use Spring Cloud Contract Verifier and not X ?

For the time being Spring Cloud Contract Verifier is a JVM based tool. So it could be your first pick when you’re already creating +software for the JVM. This project has a lot of really interesting features but especially quite a few of them definitely make +Spring Cloud Contract Verifier stand out on the "market" of Consumer Driven Contract (CDC) tooling. Out of many the most interesting are:

  • Possibility to do CDC with messaging
  • Clear and easy to use, statically typed DSL
  • Possibility to copy paste your current JSON file to the contract and only edit its elements
  • Automatic generation of tests from the defined Contract
  • Stub Runner functionality - the stubs are automatically downloaded at runtime from Nexus / Artifactory
  • Spring Cloud integration - no discovery service is needed for integration tests

86.2 I don’t want to write a contract in Groovy!

No problem. You can write a contract in YAML!

86.3 What is this value(consumer(), producer()) ?

One of the biggest challenges related to stubs is their reusability. Only if they can be vastly used, will they serve their purpose. +What typically makes that difficult are the hard-coded values of request / response elements. For example dates or ids. +Imagine the following JSON request

{
+    "time" : "2016-10-10 20:10:15",
+    "id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
+    "body" : "foo"
+}

and JSON response

{
+    "time" : "2016-10-10 21:10:15",
+    "id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
+    "body" : "bar"
+}

Imagine the pain required to set proper value of the time field (let’s assume that this content is generated by the +database) by changing the clock in the system or providing stub implementations of data providers. The same is related +to the field called id. Will you create a stubbed implementation of UUID generator? Makes little sense…​

So as a consumer you would like to send a request that matches any form of a time or any UUID. That way your system +will work as usual - will generate data and you won’t have to stub anything out. Let’s assume that in case of the aforementioned +JSON the most important part is the body field. You can focus on that and provide matching for other fields. In other words +you would like the stub to work like this:

{
+    "time" : "SOMETHING THAT MATCHES TIME",
+    "id" : "SOMETHING THAT MATCHES UUID",
+    "body" : "foo"
+}

As far as the response goes as a consumer you need a concrete value that you can operate on. So such a JSON is valid

{
+    "time" : "2016-10-10 21:10:15",
+    "id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
+    "body" : "bar"
+}

As you could see in the previous sections we generate tests from contracts. So from the producer’s side the situation looks +much different. We’re parsing the provided contract and in the test we want to send a real request to your endpoints. +So for the case of a producer for the request we can’t have any sort of matching. We need concrete values that the +producer’s backend can work on. Such a JSON would be a valid one:

{
+    "time" : "2016-10-10 20:10:15",
+    "id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
+    "body" : "foo"
+}

On the other hand from the point of view of the validity of the contract the response doesn’t necessarily have to +contain concrete values of time or id. Let’s say that you generate those on the producer side - again, you’d +have to do a lot of stubbing to ensure that you always return the same values. That’s why from the producer’s side +what you might want is the following response:

{
+    "time" : "SOMETHING THAT MATCHES TIME",
+    "id" : "SOMETHING THAT MATCHES UUID",
+    "body" : "bar"
+}

How can you then provide one time a matcher for the consumer and a concrete value for the producer and vice versa? +In Spring Cloud Contract we’re allowing you to provide a dynamic value. That means that it can differ for both +sides of the communication. You can pass the values:

Either via the value method

value(consumer(...), producer(...))
+value(stub(...), test(...))
+value(client(...), server(...))

or using the $() method

$(consumer(...), producer(...))
+$(stub(...), test(...))
+$(client(...), server(...))

You can read more about this in the Contract DSL section.

Calling value() or $() tells Spring Cloud Contract that you will be passing a dynamic value. +Inside the consumer() method you pass the value that should be used on the consumer side (in the generated stub). +Inside the producer() method you pass the value that should be used on the producer side (in the generated test).

[Tip]Tip

If on one side you have passed the regular expression and you haven’t passed the other, then the +other side will get auto-generated.

Most often you will use that method together with the regex helper method. E.g. consumer(regex('[0-9]{10}')).

To sum it up the contract for the aforementioned scenario would look more or less like this (the regular expression +for time and UUID are simplified and most likely invalid but we want to keep things very simple in this example):

org.springframework.cloud.contract.spec.Contract.make {
+				request {
+					method 'GET'
+					url '/someUrl'
+					body([
+					    time : value(consumer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
+					    id: value(consumer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
+					    body: "foo"
+					])
+				}
+			response {
+				status 200
+				body([
+					    time : value(producer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
+					    id: value([producer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
+					    body: "bar"
+					])
+			}
+}
[Important]Important

Please read the Groovy docs related to JSON to understand how to +properly structure the request / response bodies.

86.4 How to do Stubs versioning?

86.4.1 API Versioning

Let’s try to answer a question what versioning really means. If you’re referring to the API version then there are +different approaches.

  • use Hypermedia, links and do not version your API by any means
  • pass versions through headers / urls

I will not try to answer a question which approach is better. Whatever suit your needs and allows you to generate +business value should be picked.

Let’s assume that you do version your API. In that case you should provide as many contracts as many versions you support. +You can create a subfolder for every version or append it to th contract name - whatever suits you more.

86.4.2 JAR versioning

If by versioning you mean the version of the JAR that contains the stubs then there are essentially two main approaches.

Let’s assume that you’re doing Continuous Delivery / Deployment which means that you’re generating a new version of +the jar each time you go through the pipeline and that jar can go to production at any time. For example your jar version +looks like this (it got built on the 20.10.2016 at 20:15:21) :

1.0.0.20161020-201521-RELEASE

In that case your generated stub jar will look like this.

1.0.0.20161020-201521-RELEASE-stubs.jar

In this case you should inside your application.yml or @AutoConfigureStubRunner when referencing stubs provide the + latest version of the stubs. You can do that by passing the + sign. Example

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})

If the versioning however is fixed (e.g. 1.0.4.RELEASE or 2.1.1) then you have to set the concrete value of the jar +version. Example for 2.1.1.

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:2.1.1:stubs:8080"})

86.4.3 Dev or prod stubs

You can manipulate the classifier to run the tests against current development version of the stubs of other services + or the ones that were deployed to production. If you alter your build to deploy the stubs with the prod-stubs classifier + once you reach production deployment then you can run tests in one case with dev stubs and one with prod stubs.

Example of tests using development version of stubs

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})

Example of tests using production version of stubs

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:prod-stubs:8080"})

You can pass those values also via properties from your deployment pipeline.

86.5 Common repo with contracts

Another way of storing contracts other than having them with the producer is keeping them in a common place. +It can be related to security issues where the consumers can’t clone the producer’s code. Also if you keep +contracts in a single place then you, as a producer, will know how many consumers you have and which +consumer will you break with your local changes.

86.5.1 Repo structure

Let’s assume that we have a producer with coordinates com.example:server and 3 consumers: client1, +client2, client3. Then in the repository with common contracts you would have the following setup +(which you can checkout here:

├── com
+│   └── example
+│       └── server
+│           ├── client1
+│           │   └── expectation.groovy
+│           ├── client2
+│           │   └── expectation.groovy
+│           ├── client3
+│           │   └── expectation.groovy
+│           └── pom.xml
+├── mvnw
+├── mvnw.cmd
+├── pom.xml
+└── src
+    └── assembly
+        └── contracts.xml

As you can see the under the slash-delimited groupid / artifact id folder (com/example/server) you have +expectations of the 3 consumers (client1, client2 and client3). Expectations are the standard Groovy DSL +contract files as described throughout this documentation. This repository has to produce a JAR file that maps +one to one to the contents of the repo.

Example of a pom.xml inside the server folder.

<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example</groupId>
+	<artifactId>server</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+
+	<name>Server Stubs</name>
+	<description>POM used to install locally stubs for consumer side</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>1.5.21.RELEASE</version>
+		<relativePath />
+	</parent>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<java.version>1.8</java.version>
+		<spring-cloud-contract.version>1.2.8.BUILD-SNAPSHOT</spring-cloud-contract.version>
+		<spring-cloud-dependencies.version>1.3.11.BUILD-SNAPSHOT</spring-cloud-dependencies.version>
+		<excludeBuildFolders>true</excludeBuildFolders>
+	</properties>
+
+	<dependencyManagement>
+		<dependencies>
+			<dependency>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-dependencies</artifactId>
+				<version>${spring-cloud-dependencies.version}</version>
+				<type>pom</type>
+				<scope>import</scope>
+			</dependency>
+		</dependencies>
+	</dependencyManagement>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+				<version>${spring-cloud-contract.version}</version>
+				<extensions>true</extensions>
+				<configuration>
+					<!-- By default it would search under src/test/resources/ -->
+					<contractsDirectory>${project.basedir}</contractsDirectory>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+	<repositories>
+		<repository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-releases</id>
+			<name>Spring Releases</name>
+			<url>https://repo.spring.io/release</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+	</repositories>
+	<pluginRepositories>
+		<pluginRepository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-releases</id>
+			<name>Spring Releases</name>
+			<url>https://repo.spring.io/release</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+	</pluginRepositories>
+
+</project>

As you can see there are no dependencies other than the Spring Cloud Contract Maven Plugin. +Those poms are necessary for the consumer side to run mvn clean install -DskipTests to locally install + stubs of the producer project.

The pom.xml in the root folder can look like this:

<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example.standalone</groupId>
+	<artifactId>contracts</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+
+	<name>Contracts</name>
+	<description>Contains all the Spring Cloud Contracts, well, contracts. JAR used by the producers to generate tests and stubs</description>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+	</properties>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-assembly-plugin</artifactId>
+				<executions>
+					<execution>
+						<id>contracts</id>
+						<phase>prepare-package</phase>
+						<goals>
+							<goal>single</goal>
+						</goals>
+						<configuration>
+							<attach>true</attach>
+							<descriptor>${basedir}/src/assembly/contracts.xml</descriptor>
+							<!-- If you want an explicit classifier remove the following line -->
+							<appendAssemblyId>false</appendAssemblyId>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

It’s using the assembly plugin in order to build the JAR with all the contracts. Example of such setup is here:

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
+		  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	<id>project</id>
+	<formats>
+		<format>jar</format>
+	</formats>
+	<includeBaseDirectory>false</includeBaseDirectory>
+	<fileSets>
+		<fileSet>
+			<directory>${project.basedir}</directory>
+			<outputDirectory>/</outputDirectory>
+			<useDefaultExcludes>true</useDefaultExcludes>
+			<excludes>
+				<exclude>**/${project.build.directory}/**</exclude>
+				<exclude>mvnw</exclude>
+				<exclude>mvnw.cmd</exclude>
+				<exclude>.mvn/**</exclude>
+				<exclude>src/**</exclude>
+			</excludes>
+		</fileSet>
+	</fileSets>
+</assembly>

86.5.2 Workflow

The workflow would look similar to the one presented in the Step by step guide to CDC. The only difference + is that the producer doesn’t own the contracts anymore. So the consumer and the producer have to work on + common contracts in a common repository.

86.5.3 Consumer

When the consumer wants to work on the contracts offline, instead of cloning the producer code, the +consumer team clones the common repository, goes to the required producer’s folder (e.g. com/example/server) +and runs mvn clean install -DskipTests to install locally the stubs converted from the contracts.

[Tip]Tip

You need to have Maven installed locally

86.5.4 Producer

As a producer it’s enough to alter the Spring Cloud Contract Verifier to provide the URL and the dependency +of the JAR containing the contracts:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<configuration>
+		<contractsRepositoryUrl>http://link/to/your/nexus/or/artifactory/or/sth</contractsRepositoryUrl>
+		<contractDependency>
+			<groupId>com.example.standalone</groupId>
+			<artifactId>contracts</artifactId>
+		</contractDependency>
+	</configuration>
+</plugin>

With this setup the JAR with groupid com.example.standalone and artifactid contracts will be downloaded +from http://link/to/your/nexus/or/artifactory/or/sth. It will be then unpacked in a local temporary folder +and contracts present under the com/example/server will be picked as the ones used to generate the +tests and the stubs. Due to this convention the producer team will know which consumer teams will be broken +when some incompatible changes are done.

The rest of the flow looks the same.

86.6 Can I have multiple base classes for tests?

Yes! Check out the Different base classes for contracts sections +of either Gradle or Maven plugins.

86.7 How can I debug the request/response being sent by the generated tests client?

The generated tests all boil down to RestAssured in some form or fashion which relies on Apache HttpClient. HttpClient has a facility called wire logging which logs the entire request and response to HttpClient. Spring Boot has a logging common application property for doing this sort of thing, just add this to your application properties

logging.level.org.apache.http.wire=DEBUG

86.7.1 How can I debug the mapping/request/response being sent by WireMock?

Starting from version 1.2.0 we turn on WireMock logging to +info and the WireMock notifier to being verbose. Now you will +exactly know what request was received by WireMock server and which +matching response definition was picked.

To turn off this feature just bump WireMock logging to ERROR

logging.level.com.github.tomakehurst.wiremock=ERROR

86.7.2 How can I see what got registered in the HTTP server stub?

You can use the mappingsOutputFolder property on @AutoConfigureStubRunner or StubRunnerRule +to dump all mappings per artifact id. Also the port at which the given stub server was +started will be attached.

86.7.3 Can I reference the request from the response?

Yes! With version 1.1.0 we’ve added such a possibility. On the HTTP stub server side we’re providing support +for this for WireMock. In case of other HTTP server stubs you’ll have to implement the approach yourself.

86.7.4 Can I reference text from file?

Yes! With version 1.2.0 we’ve added such a possibility. It’s enough to call file(…​) method in the +DSL and provide a path relative to where the contract lays. +If you’re using YAML just use the bodyFromFile property.

Prev Up Next
85. Spring Cloud Contract Verifier Introduction Home 87. Spring Cloud Contract Verifier Setup
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89. Spring Cloud Contract Stub Runner
Prev Part XIII. Spring Cloud Contract Next

89. Spring Cloud Contract Stub Runner

One of the issues that you might encounter while using Spring Cloud Contract Verifier is +passing the generated WireMock JSON stubs from the server side to the client side (or to +various clients). The same takes place in terms of client-side generation for messaging.

Copying the JSON files and setting the client side for messaging manually is out of the +question. That is why we introduced Spring Cloud Contract Stub Runner. It can +automatically download and run the stubs for you.

89.1 Snapshot versions

Add the additional snapshot repository to your build.gradle file to use snapshot +versions, which are automatically uploaded after every successful build:

Maven.  +

<repositories>
+	<repository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+</repositories>
+<pluginRepositories>
+	<pluginRepository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+</pluginRepositories>

+

Gradle.  +

buildscript {
+	repositories {
+		mavenCentral()
+		mavenLocal()
+		maven { url "https://repo.spring.io/snapshot" }
+		maven { url "https://repo.spring.io/milestone" }
+		maven { url "https://repo.spring.io/release" }
+	}

+

89.2 Publishing Stubs as JARs

The easiest approach would be to centralize the way stubs are kept. For example, you can +keep them as jars in a Maven repository.

[Tip]Tip

For both Maven and Gradle, the setup comes ready to work. However, you can customize +it if you want to.

Maven.  +

<!-- First disable the default jar setup in the properties section -->
+<!-- we don't want the verifier to do a jar for us -->
+<spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip>
+
+<!-- Next add the assembly plugin to your build -->
+<!-- we want the assembly plugin to generate the JAR -->
+<plugin>
+	<groupId>org.apache.maven.plugins</groupId>
+	<artifactId>maven-assembly-plugin</artifactId>
+	<executions>
+		<execution>
+			<id>stub</id>
+			<phase>prepare-package</phase>
+			<goals>
+				<goal>single</goal>
+			</goals>
+			<inherited>false</inherited>
+			<configuration>
+				<attach>true</attach>
+				<descriptors>
+					$../../../../src/assembly/stub.xml
+				</descriptors>
+			</configuration>
+		</execution>
+	</executions>
+</plugin>
+
+<!-- Finally setup your assembly. Below you can find the contents of src/main/assembly/stub.xml -->
+<assembly
+	xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	<id>stubs</id>
+	<formats>
+		<format>jar</format>
+	</formats>
+	<includeBaseDirectory>false</includeBaseDirectory>
+	<fileSets>
+		<fileSet>
+			<directory>src/main/java</directory>
+			<outputDirectory>/</outputDirectory>
+			<includes>
+				<include>**com/example/model/*.*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>${project.build.directory}/classes</directory>
+			<outputDirectory>/</outputDirectory>
+			<includes>
+				<include>**com/example/model/*.*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>${project.build.directory}/snippets/stubs</directory>
+			<outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/mappings</outputDirectory>
+			<includes>
+				<include>**/*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>$../../../../src/test/resources/contracts</directory>
+			<outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/contracts</outputDirectory>
+			<includes>
+				<include>**/*.groovy</include>
+			</includes>
+		</fileSet>
+	</fileSets>
+</assembly>

+

Gradle.  +

ext {
+	contractsDir = file("mappings")
+	stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/")
+}
+
+// Automatically added by plugin:
+// copyContracts - copies contracts to the output folder from which JAR will be created
+// verifierStubsJar - JAR with a provided stub suffix
+// the presented publication is also added by the plugin but you can modify it as you wish
+
+publishing {
+	publications {
+		stubs(MavenPublication) {
+			artifactId "${project.name}-stubs"
+			artifact verifierStubsJar
+		}
+	}
+}

+

89.3 Stub Runner Core

Runs stubs for service collaborators. Treating stubs as contracts of services allows to use stub-runner as an implementation of +Consumer Driven Contracts.

Stub Runner allows you to automatically download the stubs of the provided dependencies (or pick those from the classpath), start WireMock servers for them and feed them with proper stub definitions. +For messaging, special stub routes are defined.

89.3.1 Retrieving stubs

You can pick the following options of acquiring stubs

  • Aether based solution that downloads JARs with stubs from Artifactory / Nexus
  • Classpath scanning solution that searches classpath via pattern to retrieve stubs
  • Write your own implementation of the org.springframework.cloud.contract.stubrunner.StubDownloaderBuilder for full customization

The latter example is described in the Custom Stub Runner section.

Stub downloading

If you provide the stubrunner.repositoryRoot or stubrunner.workOffline flag will be set +to true then Stub Runner will connect to the given server and download the required jars. +It will then unpack the JAR to a temporary folder and reference those files in further +contract processing.

Example:

@AutoConfigureStubRunner(repositoryRoot="https://foo.bar", ids = "com.example:beer-api-producer:+:stubs:8095")

Classpath scanning

If you DON’T provide the stubrunner.repositoryRoot and stubrunner.workOffline flag will +be set to false (that’s the default) then classpath will get scanned. Let’s look at the +following example:

@AutoConfigureStubRunner(ids = {
+    "com.example:beer-api-producer:+:stubs:8095",
+    "com.example.foo:bar:1.0.0:superstubs:8096"
+})

If you’ve added the dependencies to your classpath

Maven.  +

<dependency>
+    <groupId>com.example</groupId>
+    <artifactId>beer-api-producer-restdocs</artifactId>
+    <classifier>stubs</classifier>
+    <version>0.0.1-SNAPSHOT</version>
+    <scope>test</scope>
+    <exclusions>
+        <exclusion>
+            <groupId>*</groupId>
+            <artifactId>*</artifactId>
+        </exclusion>
+    </exclusions>
+</dependency>
+<dependency>
+    <groupId>com.example.foo</groupId>
+    <artifactId>bar</artifactId>
+    <classifier>superstubs</classifier>
+    <version>1.0.0</version>
+    <scope>test</scope>
+    <exclusions>
+        <exclusion>
+            <groupId>*</groupId>
+            <artifactId>*</artifactId>
+        </exclusion>
+    </exclusions>
+</dependency>

+

Gradle.  +

testCompile("com.example:beer-api-producer-restdocs:0.0.1-SNAPSHOT:stubs") {
+    transitive = false
+}
+testCompile("com.example.foo:bar:1.0.0:superstubs") {
+    transitive = false
+}

+

Then the following locations on your classpath will get scanned. For com.example:beer-api-producer-restdocs

  • /META-INF/com.example/beer-api-producer-restdocs/*/.*
  • /contracts/com.example/beer-api-producer-restdocs/*/.*
  • /mappings/com.example/beer-api-producer-restdocs/*/.*

and com.example.foo:bar

  • /META-INF/com.example.foo/bar/*/.*
  • /contracts/com.example.foo/bar/*/.*
  • /mappings/com.example.foo/bar/*/.*
[Tip]Tip

As you can see you have to explicitly provide the group and artifact ids when packaging the +producer stubs.

The producer would setup the contracts like this:

└── src
+    └── test
+        └── resources
+            └── contracts
+                └── com.example
+                    └── beer-api-producer-restdocs
+                        └── nested
+                            └── contract3.groovy

To achieve proper stub packaging.

Or using the Maven assembly plugin or +Gradle Jar task you have to create the following +structure in your stubs jar.

└── META-INF
+    └── com.example
+        └── beer-api-producer-restdocs
+            └── 2.0.0
+                ├── contracts
+                │   └── nested
+                │       └── contract2.groovy
+                └── mappings
+                    └── mapping.json

By maintaining this structure classpath gets scanned and you can profit from the messaging / +HTTP stubs without the need to download artifacts.

89.3.2 Running stubs

Running using main app

You can set the following options to the main class:

-c, --classifier                Suffix for the jar containing stubs (e.
+                                  g. 'stubs' if the stub jar would
+                                  have a 'stubs' classifier for stubs:
+                                  foobar-stubs ). Defaults to 'stubs'
+                                  (default: stubs)
+--maxPort, --maxp <Integer>     Maximum port value to be assigned to
+                                  the WireMock instance. Defaults to
+                                  15000 (default: 15000)
+--minPort, --minp <Integer>     Minimum port value to be assigned to
+                                  the WireMock instance. Defaults to
+                                  10000 (default: 10000)
+-p, --password                  Password to user when connecting to
+                                  repository
+--phost, --proxyHost            Proxy host to use for repository
+                                  requests
+--pport, --proxyPort [Integer]  Proxy port to use for repository
+                                  requests
+-r, --root                      Location of a Jar containing server
+                                  where you keep your stubs (e.g. http:
+                                  //nexus.
+                                  net/content/repositories/repository)
+-s, --stubs                     Comma separated list of Ivy
+                                  representation of jars with stubs.
+                                  Eg. groupid:artifactid1,groupid2:
+                                  artifactid2:classifier
+-u, --username                  Username to user when connecting to
+                                  repository
+--wo, --workOffline             Switch to work offline. Defaults to
+                                  'false'

HTTP Stubs

Stubs are defined in JSON documents, whose syntax is defined in WireMock documentation

Example:

{
+    "request": {
+        "method": "GET",
+        "url": "/ping"
+    },
+    "response": {
+        "status": 200,
+        "body": "pong",
+        "headers": {
+            "Content-Type": "text/plain"
+        }
+    }
+}

Viewing registered mappings

Every stubbed collaborator exposes list of defined mappings under __/admin/ endpoint.

You can also use the mappingsOutputFolder property to dump the mappings to files. + For annotation based approach it would look like this

@AutoConfigureStubRunner(ids="a.b.c:loanIssuance,a.b.c:fraudDetectionServer",
+mappingsOutputFolder = "target/outputmappings/")

and for the JUnit approach like this:

@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule()
+			.repoRoot("http://some_url")
+			.downloadStub("a.b.c", "loanIssuance")
+			.downloadStub("a.b.c:fraudDetectionServer")
+			.withMappingsOutputFolder("target/outputmappings")

Then if you check out the folder target/outputmappings you would see the following structure

.
+├── fraudDetectionServer_13705
+└── loanIssuance_12255

That means that there were two stubs registered. fraudDetectionServer was registered at port 13705 +and loanIssuance at port 12255. If we take a look at one of the files we would see (for WireMock) +mappings available for the given server:

[{
+  "id" : "f9152eb9-bf77-4c38-8289-90be7d10d0d7",
+  "request" : {
+    "url" : "/name",
+    "method" : "GET"
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "fraudDetectionServer"
+  },
+  "uuid" : "f9152eb9-bf77-4c38-8289-90be7d10d0d7"
+},
+...
+]

Messaging Stubs

Depending on the provided Stub Runner dependency and the DSL the messaging routes are automatically set up.

89.4 Stub Runner JUnit Rule

Stub Runner comes with a JUnit rule thanks to which you can very easily download and run stubs for given group and artifact id:

@ClassRule public static StubRunnerRule rule = new StubRunnerRule()
+		.repoRoot(repoRoot())
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer");

After that rule gets executed Stub Runner connects to your Maven repository and for the given list of dependencies tries to:

  • download them
  • cache them locally
  • unzip them to a temporary folder
  • start a WireMock server for each Maven dependency on a random port from the provided range of ports / provided port
  • feed the WireMock server with all JSON files that are valid WireMock definitions
  • can also send messages (remember to pass an implementation of MessageVerifier interface)

Stub Runner uses Eclipse Aether mechanism to download the Maven dependencies. +Check their docs for more information.

Since the StubRunnerRule implements the StubFinder it allows you to find the started stubs:

package org.springframework.cloud.contract.stubrunner;
+
+import java.net.URL;
+import java.util.Collection;
+import java.util.Map;
+
+import org.springframework.cloud.contract.spec.Contract;
+
+public interface StubFinder extends StubTrigger {
+	/**
+	 * For the given groupId and artifactId tries to find the matching
+	 * URL of the running stub.
+	 *
+	 * @param groupId - might be null. In that case a search only via artifactId takes place
+	 * @return URL of a running stub or throws exception if not found
+	 */
+	URL findStubUrl(String groupId, String artifactId) throws StubNotFoundException;
+
+	/**
+	 * For the given Ivy notation {@code [groupId]:artifactId:[version]:[classifier]} tries to
+	 * find the matching URL of the running stub. You can also pass only {@code artifactId}.
+	 *
+	 * @param ivyNotation - Ivy representation of the Maven artifact
+	 * @return URL of a running stub or throws exception if not found
+	 */
+	URL findStubUrl(String ivyNotation) throws StubNotFoundException;
+
+	/**
+	 * Returns all running stubs
+	 */
+	RunningStubs findAllRunningStubs();
+
+	/**
+	 * Returns the list of Contracts
+	 */
+	Map<StubConfiguration, Collection<Contract>> getContracts();
+}

Example of usage in Spock tests:

@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule()
+		.repoRoot(StubRunnerRuleSpec.getResource("/m2repo/repository").toURI().toString())
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")
+		.withMappingsOutputFolder("target/outputmappingsforrule")
+
+
+def 'should start WireMock servers'() {
+	expect: 'WireMocks are running'
+		rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null
+		rule.findStubUrl('loanIssuance') != null
+		rule.findStubUrl('loanIssuance') == rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance')
+		rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null
+	and:
+		rule.findAllRunningStubs().isPresent('loanIssuance')
+		rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer')
+		rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer')
+	and: 'Stubs were registered'
+		"${rule.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
+		"${rule.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
+}
+
+def 'should output mappings to output folder'() {
+	when:
+		def url = rule.findStubUrl('fraudDetectionServer')
+	then:
+		new File("target/outputmappingsforrule", "fraudDetectionServer_${url.port}").exists()
+}

Example of usage in JUnit tests:

@Test
+public void should_start_wiremock_servers() throws Exception {
+	// expect: 'WireMocks are running'
+		then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")).isNotNull();
+		then(rule.findStubUrl("loanIssuance")).isNotNull();
+		then(rule.findStubUrl("loanIssuance")).isEqualTo(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance"));
+		then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isNotNull();
+	// and:
+		then(rule.findAllRunningStubs().isPresent("loanIssuance")).isTrue();
+		then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs", "fraudDetectionServer")).isTrue();
+		then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isTrue();
+	// and: 'Stubs were registered'
+		then(httpGet(rule.findStubUrl("loanIssuance").toString() + "/name")).isEqualTo("loanIssuance");
+		then(httpGet(rule.findStubUrl("fraudDetectionServer").toString() + "/name")).isEqualTo("fraudDetectionServer");
+}

Check the Common properties for JUnit and Spring for more information on how to apply global configuration of Stub Runner.

[Important]Important

To use the JUnit rule together with messaging you have to provide an implementation of the +MessageVerifier interface to the rule builder (e.g. rule.messageVerifier(new MyMessageVerifier())). +If you don’t do this then whenever you try to send a message an exception will be thrown.

89.4.1 Maven settings

The stub downloader honors Maven settings for a different local repository folder. +Authentication details for repositories and profiles are currently not taken into account, so you need to specify it using the properties mentioned above.

89.4.2 Providing fixed ports

You can also run your stubs on fixed ports. You can do it in two different ways. One is to pass it in the properties, and the other via fluent API of +JUnit rule.

89.4.3 Fluent API

When using the StubRunnerRule you can add a stub to download and then pass the port for the last downloaded stub.

@ClassRule public static StubRunnerRule rule = new StubRunnerRule()
+		.repoRoot(repoRoot())
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
+		.withPort(12345)
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer:12346");

You can see that for this example the following test is valid:

then(rule.findStubUrl("loanIssuance")).isEqualTo(URI.create("http://localhost:12345").toURL());
+then(rule.findStubUrl("fraudDetectionServer")).isEqualTo(URI.create("http://localhost:12346").toURL());

89.4.4 Stub Runner with Spring

Sets up Spring configuration of the Stub Runner project.

By providing a list of stubs inside your configuration file the Stub Runner automatically downloads +and registers in WireMock the selected stubs.

If you want to find the URL of your stubbed dependency you can autowire the StubFinder interface and use +its methods as presented below:

@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
+@SpringBootTest(properties = [" stubrunner.cloud.enabled=false",
+		"stubrunner.camel.enabled=false",
+		'foo=${stubrunner.runningstubs.fraudDetectionServer.port}'])
+@AutoConfigureStubRunner(mappingsOutputFolder = "target/outputmappings/")
+@ActiveProfiles("test")
+class StubRunnerConfigurationSpec extends Specification {
+
+	@Autowired StubFinder stubFinder
+	@Autowired Environment environment
+	@Value('${foo}') Integer foo
+
+	@BeforeClass
+	@AfterClass
+	void setupProps() {
+		System.clearProperty("stubrunner.repository.root")
+		System.clearProperty("stubrunner.classifier")
+	}
+
+	def 'should start WireMock servers'() {
+		expect: 'WireMocks are running'
+			stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null
+			stubFinder.findStubUrl('loanIssuance') != null
+			stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance')
+			stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance')
+			stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs')
+			stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null
+		and:
+			stubFinder.findAllRunningStubs().isPresent('loanIssuance')
+			stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer')
+			stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer')
+		and: 'Stubs were registered'
+			"${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
+			"${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
+	}
+
+	def 'should throw an exception when stub is not found'() {
+		when:
+			stubFinder.findStubUrl('nonExistingService')
+		then:
+			thrown(StubNotFoundException)
+		when:
+			stubFinder.findStubUrl('nonExistingGroupId', 'nonExistingArtifactId')
+		then:
+			thrown(StubNotFoundException)
+	}
+
+	def 'should register started servers as environment variables'() {
+		expect:
+			environment.getProperty("stubrunner.runningstubs.loanIssuance.port") != null
+			stubFinder.findAllRunningStubs().getPort("loanIssuance") == (environment.getProperty("stubrunner.runningstubs.loanIssuance.port") as Integer)
+		and:
+			environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") != null
+			stubFinder.findAllRunningStubs().getPort("fraudDetectionServer") == (environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") as Integer)
+	}
+
+	def 'should be able to interpolate a running stub in the passed test property'() {
+		given:
+			int fraudPort = stubFinder.findAllRunningStubs().getPort("fraudDetectionServer")
+		expect:
+			fraudPort > 0
+			environment.getProperty("foo", Integer) == fraudPort
+			foo == fraudPort
+	}
+
+	def 'should dump all mappings to a file'() {
+		when:
+			def url = stubFinder.findStubUrl("fraudDetectionServer")
+		then:
+			new File("target/outputmappings/", "fraudDetectionServer_${url.port}").exists()
+	}
+
+	@Configuration
+	@EnableAutoConfiguration
+	static class Config {}
+}

for the following configuration file:

stubrunner:
+  repositoryRoot: classpath:m2repo/repository/
+  ids:
+    - org.springframework.cloud.contract.verifier.stubs:loanIssuance
+    - org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer
+    - org.springframework.cloud.contract.verifier.stubs:bootService

Instead of using the properties you can also use the properties inside the @AutoConfigureStubRunner. +Below you can find an example of achieving the same result by setting values on the annotation.

@AutoConfigureStubRunner(
+		ids = ["org.springframework.cloud.contract.verifier.stubs:loanIssuance",
+		"org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer",
+		"org.springframework.cloud.contract.verifier.stubs:bootService"],
+		repositoryRoot = "classpath:m2repo/repository/")

Stub Runner Spring registers environment variables in the following manner +for every registered WireMock server. Example for Stub Runner ids + com.example:foo, com.example:bar.

  • stubrunner.runningstubs.foo.port
  • stubrunner.runningstubs.bar.port

Which you can reference in your code.

89.5 Stub Runner Spring Cloud

Stub Runner can integrate with Spring Cloud.

For real life examples you can check the

89.5.1 Stubbing Service Discovery

The most important feature of Stub Runner Spring Cloud is the fact that it’s stubbing

  • DiscoveryClient
  • Ribbon ServerList

that means that regardless of the fact whether you’re using Zookeeper, Consul, Eureka or anything else, you don’t need that in your tests. +We’re starting WireMock instances of your dependencies and we’re telling your application whenever you’re using Feign, load balanced RestTemplate +or DiscoveryClient directly, to call those stubbed servers instead of calling the real Service Discovery tool.

For example this test will pass

def 'should make service discovery work'() {
+	expect: 'WireMocks are running'
+		"${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
+		"${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
+	and: 'Stubs can be reached via load service discovery'
+		restTemplate.getForObject('http://loanIssuance/name', String) == 'loanIssuance'
+		restTemplate.getForObject('http://someNameThatShouldMapFraudDetectionServer/name', String) == 'fraudDetectionServer'
+}

for the following configuration file

stubrunner:
+  idsToServiceIds:
+    ivyNotation: someValueInsideYourCode
+    fraudDetectionServer: someNameThatShouldMapFraudDetectionServer

Test profiles and service discovery

In your integration tests you typically don’t want to call neither a discovery service (e.g. Eureka) +or Config Server. That’s why you create an additional test configuration in which you want to disable +these features.

Due to certain limitations of spring-cloud-commons to achieve this you have disable these properties +via a static block like presented below (example for Eureka)

    //Hack to work around https://github.com/spring-cloud/spring-cloud-commons/issues/156
+    static {
+        System.setProperty("eureka.client.enabled", "false");
+        System.setProperty("spring.cloud.config.failFast", "false");
+    }

89.5.2 Additional Configuration

You can match the artifactId of the stub with the name of your app by using the stubrunner.idsToServiceIds: map. +You can disable Stub Runner Ribbon support by providing: stubrunner.cloud.ribbon.enabled equal to false +You can disable Stub Runner support by providing: stubrunner.cloud.enabled equal to false

[Tip]Tip

By default all service discovery will be stubbed. That means that regardless of the fact if you have +an existing DiscoveryClient its results will be ignored. However, if you want to reuse it, just set + stubrunner.cloud.delegate.enabled to true and then your existing DiscoveryClient results will be + merged with the stubbed ones.

The default Maven configuration used by Stub Runner can be tweaked either +via the following system properties or environment variables

  • maven.repo.local - path to the custom maven local repository location
  • org.apache.maven.user-settings - path to custom maven user settings location
  • org.apache.maven.global-settings - path to maven global settings location

89.6 Stub Runner Boot Application

Spring Cloud Contract Stub Runner Boot is a Spring Boot application that exposes REST endpoints to +trigger the messaging labels and to access started WireMock servers.

One of the use-cases is to run some smoke (end to end) tests on a deployed application. +You can check out the Spring Cloud Pipelines +project for more information.

89.6.1 How to use it?

Stub Runner Server

Just add the

compile "org.springframework.cloud:spring-cloud-starter-stub-runner"

Annotate a class with @EnableStubRunnerServer, build a fat-jar and you’re ready to go!

For the properties check the Stub Runner Spring section.

Stub Runner Server Fat Jar

You can download a standalone JAR from Maven (for example, for version 1.2.3.RELEASE), as follows:

$ wget -O stub-runner.jar 'https://search.maven.org/remote_content?g=org.springframework.cloud&a=spring-cloud-contract-stub-runner-boot&v=1.2.3.RELEASE'
+$ java -jar stub-runner.jar --stubrunner.ids=... --stubrunner.repositoryRoot=...

Spring Cloud CLI

Starting from 1.4.0.RELEASE version of the Spring Cloud CLI +project you can start Stub Runner Boot by executing spring cloud stubrunner.

In order to pass the configuration just create a stubrunner.yml file in the current working directory +or a subdirectory called config or in ~/.spring-cloud. The file could look like this +(example for running stubs installed locally)

stubrunner.yml.  +

stubrunner:
+  workOffline: true
+  ids:
+    - com.example:beer-api-producer:+:9876

+

and then just call spring cloud stubrunner from your terminal window to start +the Stub Runner server. It will be available at port 8750.

89.6.2 Endpoints

HTTP

  • GET /stubs - returns a list of all running stubs in ivy:integer notation
  • GET /stubs/{ivy} - returns a port for the given ivy notation (when calling the endpoint ivy can also be artifactId only)

Messaging

For Messaging

  • GET /triggers - returns a list of all running labels in ivy : [ label1, label2 …​] notation
  • POST /triggers/{label} - executes a trigger with label
  • POST /triggers/{ivy}/{label} - executes a trigger with label for the given ivy notation (when calling the endpoint ivy can also be artifactId only)

89.6.3 Example

@ContextConfiguration(classes = StubRunnerBoot, loader = SpringBootContextLoader)
+@SpringBootTest(properties = "spring.cloud.zookeeper.enabled=false")
+@ActiveProfiles("test")
+class StubRunnerBootSpec extends Specification {
+
+	@Autowired StubRunning stubRunning
+
+	def setup() {
+		RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning),
+				new TriggerController(stubRunning))
+	}
+
+	def 'should return a list of running stub servers in "full ivy:port" notation'() {
+		when:
+			String response = RestAssuredMockMvc.get('/stubs').body.asString()
+		then:
+			def root = new JsonSlurper().parseText(response)
+			root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs' instanceof Integer
+	}
+
+	def 'should return a port on which a [#stubId] stub is running'() {
+		when:
+			def response = RestAssuredMockMvc.get("/stubs/${stubId}")
+		then:
+			response.statusCode == 200
+			response.body.as(Integer) > 0
+		where:
+			stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:+:stubs',
+					   'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs',
+					   'org.springframework.cloud.contract.verifier.stubs:bootService:+',
+					   'org.springframework.cloud.contract.verifier.stubs:bootService',
+					   'bootService']
+	}
+
+	def 'should return 404 when missing stub was called'() {
+		when:
+			def response = RestAssuredMockMvc.get("/stubs/a:b:c:d")
+		then:
+			response.statusCode == 404
+	}
+
+	def 'should return a list of messaging labels that can be triggered when version and classifier are passed'() {
+		when:
+			String response = RestAssuredMockMvc.get('/triggers').body.asString()
+		then:
+			def root = new JsonSlurper().parseText(response)
+			root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs'?.containsAll(["delete_book","return_book_1","return_book_2"])
+	}
+
+	def 'should trigger a messaging label'() {
+		given:
+			StubRunning stubRunning = Mock()
+			RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning))
+		when:
+			def response = RestAssuredMockMvc.post("/triggers/delete_book")
+		then:
+			response.statusCode == 200
+		and:
+			1 * stubRunning.trigger('delete_book')
+	}
+
+	def 'should trigger a messaging label for a stub with [#stubId] ivy notation'() {
+		given:
+			StubRunning stubRunning = Mock()
+			RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning))
+		when:
+			def response = RestAssuredMockMvc.post("/triggers/$stubId/delete_book")
+		then:
+			response.statusCode == 200
+		and:
+			1 * stubRunning.trigger(stubId, 'delete_book')
+		where:
+			stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:stubs', 'org.springframework.cloud.contract.verifier.stubs:bootService', 'bootService']
+	}
+
+	def 'should throw exception when trigger is missing'() {
+		when:
+			RestAssuredMockMvc.post("/triggers/missing_label")
+		then:
+			Exception e = thrown(Exception)
+			e.message.contains("Exception occurred while trying to return [missing_label] label.")
+			e.message.contains("Available labels are")
+			e.message.contains("org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs=[]")
+			e.message.contains("org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs=")
+	}
+
+}

89.6.4 Stub Runner Boot with Service Discovery

One of the possibilities of using Stub Runner Boot is to use it as a feed of stubs for "smoke-tests". What does it mean? + Let’s assume that you don’t want to deploy 50 microservice to a test environment in order + to check if your application is working fine. You’ve already executed a suite of tests during the build process + but you would also like to ensure that the packaging of your application is fine. What you can do + is to deploy your application to an environment, start it and run a couple of tests on it to see if + it’s working fine. We can call those tests smoke-tests since their idea is to check only a handful + of testing scenarios.

The problem with this approach is such that if you’re doing microservices most likely you’re + using a service discovery tool. Stub Runner Boot allows you to solve this issue by starting the + required stubs and register them in a service discovery tool. Let’s take a look at an example of + such a setup with Eureka. Let’s assume that Eureka was already running.

@SpringBootApplication
+@EnableStubRunnerServer
+@EnableEurekaClient
+@AutoConfigureStubRunner
+public class StubRunnerBootEurekaExample {
+
+	public static void main(String[] args) {
+		SpringApplication.run(StubRunnerBootEurekaExample.class, args);
+	}
+
+}

As you can see we want to start a Stub Runner Boot server @EnableStubRunnerServer, enable Eureka client @EnableEurekaClient +and we want to have the stub runner feature turned on @AutoConfigureStubRunner.

Now let’s assume that we want to start this application so that the stubs get automatically registered. + We can do it by running the app java -jar ${SYSTEM_PROPS} stub-runner-boot-eureka-example.jar where + ${SYSTEM_PROPS} would contain the following list of properties

-Dstubrunner.repositoryRoot=https://repo.spring.io/snapshot (1)
+-Dstubrunner.cloud.stubbed.discovery.enabled=false (2)
+-Dstubrunner.ids=org.springframework.cloud.contract.verifier.stubs:loanIssuance,org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer,org.springframework.cloud.contract.verifier.stubs:bootService (3)
+-Dstubrunner.idsToServiceIds.fraudDetectionServer=someNameThatShouldMapFraudDetectionServer (4)
+
+(1) - we tell Stub Runner where all the stubs reside
+(2) - we don't want the default behaviour where the discovery service is stubbed. That's why the stub registration will be picked
+(3) - we provide a list of stubs to download
+(4) - we provide a list of artifactId to serviceId mapping

That way your deployed application can send requests to started WireMock servers via the service +discovery. Most likely points 1-3 could be set by default in application.yml cause they are not +likely to change. That way you can provide only the list of stubs to download whenever you start +the Stub Runner Boot.

89.7 Stubs Per Consumer

There are cases in which 2 consumers of the same endpoint want to have 2 different responses.

[Tip]Tip

This approach also allows you to immediately know which consumer is using which part of your API. +You can remove part of a response that your API produces and you can see which of your autogenerated tests +fails. If none fails then you can safely delete that part of the response cause nobody is using it.

Let’s look at the following example for contract defined for the producer called producer. +There are 2 consumers: foo-consumer and bar-consumer.

Consumer foo-service

request {
+   url '/foo'
+   method GET()
+}
+response {
+    status 200
+    body(
+       foo: "foo"
+    }
+}

Consumer bar-service

request {
+   url '/foo'
+   method GET()
+}
+response {
+    status 200
+    body(
+       bar: "bar"
+    }
+}

You can’t produce for the same request 2 different responses. That’s why you can properly package the +contracts and then profit from the stubsPerConsumer feature.

On the producer side the consumers can have a folder that contains contracts related only to them. +By setting the stubrunner.stubs-per-consumer flag to true we no longer register all stubs but only those that +correspond to the consumer application’s name. In other words we’ll scan the path of every stub and +if it contains the subfolder with name of the consumer in the path only then will it get registered.

On the foo producer side the contracts would look like this

.
+└── contracts
+    ├── bar-consumer
+    │   ├── bookReturnedForBar.groovy
+    │   └── shouldCallBar.groovy
+    └── foo-consumer
+        ├── bookReturnedForFoo.groovy
+        └── shouldCallFoo.groovy

Being the bar-consumer consumer you can either set the spring.application.name or the stubrunner.consumer-name to bar-consumer +Or set the test as follows:

@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
+@SpringBootTest(properties = ["spring.application.name=bar-consumer"])
+@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers",
+		repositoryRoot = "classpath:m2repo/repository/",
+		stubsPerConsumer = true)
+class StubRunnerStubsPerConsumerSpec extends Specification {
+...
+}

Then only the stubs registered under a path that contains the bar-consumer in its name (i.e. those from the +src/test/resources/contracts/bar-consumer/some/contracts/…​ folder) will be allowed to be referenced.

Or set the consumer name explicitly

@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
+@SpringBootTest
+@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers",
+		repositoryRoot = "classpath:m2repo/repository/",
+		consumerName = "foo-consumer",
+		stubsPerConsumer = true)
+class StubRunnerStubsPerConsumerWithConsumerNameSpec extends Specification {
+...
+}

Then only the stubs registered under a path that contains the foo-consumer in its name (i.e. those from the +src/test/resources/contracts/foo-consumer/some/contracts/…​ folder) will be allowed to be referenced.

You can check out issue 224 for more +information about the reasons behind this change.

89.8 Common

This section briefly describes common properties, including:

89.8.1 Common Properties for JUnit and Spring

You can set repetitive properties by using system properties or Spring configuration +properties. Here are their names with their default values:

Property nameDefault valueDescription

stubrunner.minPort

10000

Minimum value of a port for a started WireMock with stubs.

stubrunner.maxPort

15000

Maximum value of a port for a started WireMock with stubs.

stubrunner.repositoryRoot

 

Maven repo URL. If blank, then call the local maven repo.

stubrunner.classifier

stubs

Default classifier for the stub artifacts.

stubrunner.workOffline

false

If true, then do not contact any remote repositories to +download stubs.

stubrunner.ids

 

Array of Ivy notation stubs to download.

stubrunner.username

 

Optional username to access the tool that stores the JARs with +stubs.

stubrunner.password

 

Optional password to access the tool that stores the JARs with +stubs.

stubrunner.stubsPerConsumer

false

Set to true if you want to use different stubs for +each consumer instead of registering all stubs for every consumer.

stubrunner.consumerName

 

If you want to use a stub for each consumer and want to +override the consumer name just change this value.

89.8.2 Stub Runner Stubs IDs

You can provide the stubs to download via the stubrunner.ids system property. They +follow this pattern:

groupId:artifactId:version:classifier:port

Note that version, classifier and port are optional.

  • If you do not provide the port, a random one will be picked.
  • If you do not provide the classifier, the default is used. (Note that you can +pass an empty classifier this way: groupId:artifactId:version:).
  • If you do not provide the version, then the + will be passed and the latest one is +downloaded.

port means the port of the WireMock server.

[Important]Important

Starting with version 1.0.4, you can provide a range of versions that you +would like the Stub Runner to take into consideration. You can read more about the +Aether versioning +ranges here.

89.9 Stub Runner Docker

We’re publishing a spring-cloud/spring-cloud-contract-stub-runner Docker image +that will start the standalone version of Stub Runner.

If you want to learn more about the basics of Maven, artifact ids, +group ids, classifiers and Artifact Managers, just click here Section 87.6, “Docker Project”.

89.9.1 How to use it

Just execute the docker image. You can pass any of the Section 89.8.1, “Common Properties for JUnit and Spring” +as environment variables. The convention is that all the +letters should be upper case. The camel case notation should +and the dot (.) should be separated via underscore (_). E.g. + the stubrunner.repositoryRoot property should be represented + as a STUBRUNNER_REPOSITORY_ROOT environment variable.

89.9.2 Example of client side usage in a non JVM project

We’d like to use the stubs created in this Section 87.6.4, “Server side (nodejs)” step. +Let’s assume that we want to run the stubs on port 9876. The NodeJS code +is available here:

$ git clone https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs
+$ cd bookstore

Let’s run the Stub Runner Boot application with the stubs.

# Provide the Spring Cloud Contract Docker version
+$ SC_CONTRACT_DOCKER_VERSION="..."
+# The IP at which the app is running and Docker container can reach it
+$ APP_IP="192.168.0.100"
+# Spring Cloud Contract Stub Runner properties
+$ STUBRUNNER_PORT="8083"
+# Stub coordinates 'groupId:artifactId:version:classifier:port'
+$ STUBRUNNER_IDS="com.example:bookstore:0.0.1.RELEASE:stubs:9876"
+$ STUBRUNNER_REPOSITORY_ROOT="http://${APP_IP}:8081/artifactory/libs-release-local"
+# Run the docker with Stub Runner Boot
+$ docker run  --rm -e "STUBRUNNER_IDS=${STUBRUNNER_IDS}" -e "STUBRUNNER_REPOSITORY_ROOT=${STUBRUNNER_REPOSITORY_ROOT}" -p "${STUBRUNNER_PORT}:${STUBRUNNER_PORT}" -p "9876:9876" springcloud/spring-cloud-contract-stub-runner:"${SC_CONTRACT_DOCKER_VERSION}"

What’s happening is that

  • a standalone Stub Runner application got started
  • it downloaded the stub with coordinates com.example:bookstore:0.0.1.RELEASE:stubs on port 9876
  • it got downloaded from Artifactory running at http://192.168.0.100:8081/artifactory/libs-release-local
  • after a while Stub Runner will be running on port 8083
  • and the stubs will be running at port 9876

On the server side we built a stateful stub. Let’s use curl to assert +that the stubs are setup properly.

# let's execute the first request (no response is returned)
+$ curl -H "Content-Type:application/json" -X POST --data '{ "title" : "Title", "genre" : "Genre", "description" : "Description", "author" : "Author", "publisher" : "Publisher", "pages" : 100, "image_url" : "https://d213dhlpdb53mu.cloudfront.net/assets/pivotal-square-logo-41418bd391196c3022f3cd9f3959b3f6d7764c47873d858583384e759c7db435.svg", "buy_url" : "https://pivotal.io" }' http://localhost:9876/api/books
+# Now time for the second request
+$ curl -X GET http://localhost:9876/api/books
+# You will receive contents of the JSON
Prev Up Next
88. Spring Cloud Contract Verifier Messaging Home 90. Stub Runner for Messaging
\ No newline at end of file diff --git a/Edgware.SR6/multi/multi__spring_cloud_contract_verifier_introduction.html b/Edgware.SR6/multi/multi__spring_cloud_contract_verifier_introduction.html new file mode 100644 index 00000000..a014d12b --- /dev/null +++ b/Edgware.SR6/multi/multi__spring_cloud_contract_verifier_introduction.html @@ -0,0 +1,559 @@ + + + 85. Spring Cloud Contract Verifier Introduction
85. Spring Cloud Contract Verifier Introduction
Prev Part XIII. Spring Cloud Contract Next

85. Spring Cloud Contract Verifier Introduction

[Tip]Tip

The Accurest project was initially started by Marcin Grzejszczak and Jakub Kubrynski +(Codearte)

Spring Cloud Contract Verifier enables Consumer Driven Contract (CDC) development of +JVM-based applications. It moves TDD to the level of software architecture.

Spring Cloud Contract Verifier ships with Contract Definition Language (CDL). Contract +definitions are used to produce the following resources:

  • JSON stub definitions to be used by WireMock when doing integration testing on the +client code (client tests). Test code must still be written by hand, and test data is +produced by Spring Cloud Contract Verifier.
  • Messaging routes, if you’re using a messaging service. We integrate with Spring +Integration, Spring Cloud Stream, Spring AMQP, and Apache Camel. You can also set your +own integrations.
  • Acceptance tests (in JUnit or Spock) are used to verify if server-side implementation +of the API is compliant with the contract (server tests). A full test is generated by +Spring Cloud Contract Verifier.

85.1 Why a Contract Verifier?

Assume that we have a system consisting of multiple microservices:

Microservices Architecture

85.1.1 Testing issues

If we wanted to test the application in top left corner to determine whether it can +communicate with other services, we could do one of two things:

  • Deploy all microservices and perform end-to-end tests.
  • Mock other microservices in unit/integration tests.

Both have their advantages but also a lot of disadvantages.

Deploy all microservices and perform end to end tests

Advantages:

  • Simulates production.
  • Tests real communication between services.

Disadvantages:

  • To test one microservice, we have to deploy 6 microservices, a couple of databases, +etc.
  • The environment where the tests run is locked for a single suite of tests (nobody else +would be able to run the tests in the meantime).
  • They take a long time to run.
  • The feedback comes very late in the process.
  • They are extremely hard to debug.

Mock other microservices in unit/integration tests

Advantages:

  • They provide very fast feedback.
  • They have no infrastructure requirements.

Disadvantages:

  • The implementor of the service creates stubs that might have nothing to do with +reality.
  • You can go to production with passing tests and failing production.

To solve the aforementioned issues, Spring Cloud Contract Verifier with Stub Runner was +created. The main idea is to give you very fast feedback, without the need to set up the +whole world of microservices. If you work on stubs, then the only applications you need +are those that your application directly uses.

Stubbed Services

Spring Cloud Contract Verifier gives you the certainty that the stubs that you use were +created by the service that you’re calling. Also, if you can use them, it means that they +were tested against the producer’s side. In short, you can trust those stubs.

85.2 Purposes

The main purposes of Spring Cloud Contract Verifier with Stub Runner are:

  • To ensure that WireMock/Messaging stubs (used when developing the client) do exactly +what the actual server-side implementation does.
  • To promote ATDD method and Microservices architectural style.
  • To provide a way to publish changes in contracts that are immediately visible on both +sides.
  • To generate boilerplate test code to be used on the server side.
[Important]Important

Spring Cloud Contract Verifier’s purpose is NOT to start writing business +features in the contracts. Assume that we have a business use case of fraud check. If a +user can be a fraud for 100 different reasons, we would assume that you would create 2 +contracts, one for the positive case and one for the negative case. Contract tests are +used to test contracts between applications and not to simulate full behavior.

85.3 How It Works

This section explores how Spring Cloud Contract Verifier with Stub Runner works.

85.3.1 Defining the contract

As consumers of services, we need to define what exactly we want to achieve. We need to +formulate our expectations. That is why we write contracts.

Assume that you want to send a request containing the ID of a client company and the +amount it wants to borrow from us. You also want to send it to the /fraudcheck url via +the PUT method.

Groovy DSL.  +

package contracts
+
+org.springframework.cloud.contract.spec.Contract.make {
+	request { // (1)
+		method 'PUT' // (2)
+		url '/fraudcheck' // (3)
+		body([ // (4)
+			   "client.id": $(regex('[0-9]{10}')),
+			   loanAmount: 99999
+		])
+		headers { // (5)
+			contentType('application/json')
+		}
+	}
+	response { // (6)
+		status 200 // (7)
+		body([ // (8)
+			   fraudCheckStatus: "FRAUD",
+			   "rejection.reason": "Amount too high"
+		])
+		headers { // (9)
+			contentType('application/json')
+		}
+	}
+}
+
+/*
+From the Consumer perspective, when shooting a request in the integration test:
+
+(1) - If the consumer sends a request
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the response will be sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` equal to `application/json`
+
+From the Producer perspective, in the autogenerated producer-side test:
+
+(1) - A request will be sent to the producer
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that will have a generated value that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the test will assert if the response has been sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` matching `application/json.*`
+ */

+

YAML.  +

request: # (1)
+  method: PUT # (2)
+  url: /fraudcheck # (3)
+  body: # (4)
+    "client.id": 1234567890
+    loanAmount: 99999
+  headers: # (5)
+    Content-Type: application/json
+  matchers:
+    body:
+      - path: $.['client.id'] # (6)
+        type: by_regex
+        value: "[0-9]{10}"
+response: # (7)
+  status: 200 # (8)
+  body:  # (9)
+    fraudCheckStatus: "FRAUD"
+    "rejection.reason": "Amount too high"
+  headers: # (10)
+    Content-Type: application/json;charset=UTF-8
+
+
+#From the Consumer perspective, when shooting a request in the integration test:
+#
+#(1) - If the consumer sends a request
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}`
+#(7) - then the response will be sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json`
+#
+#From the Producer perspective, in the autogenerated producer-side test:
+#
+#(1) - A request will be sent to the producer
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id` `1234567890`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(7) - then the test will assert if the response has been sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8`

+

85.3.2 Client Side

Spring Cloud Contract generates stubs, which you can use during client-side testing. +You get a running WireMock instance/Messaging route that simulates the service. +You would like to feed that instance with a proper stub definition.

At some point in time, you need to send a request to the Fraud Detection service.

ResponseEntity<FraudServiceResponse> response =
+		restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
+				new HttpEntity<>(request, httpHeaders),
+				FraudServiceResponse.class);

Annotate your test class with @AutoConfigureStubRunner. In the annotation provide the group id and artifact id for the Stub Runner to download stubs of your collaborators.

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment=WebEnvironment.NONE)
+@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
+public class LoanApplicationServiceTests {

After that, during the tests, Spring Cloud Contract automatically finds the stubs +(simulating the real service) in the Maven repository and exposes them on a configured +(or random) port.

85.3.3 Server Side

Since you are developing your stub, you need to be sure that it actually resembles your +concrete implementation. You cannot have a situation where your stub acts in one way and +your application behaves in a different way, especially in production.

To ensure that your application behaves the way you define in your stub, tests are +generated from the stub you provide.

The autogenerated test looks, more or less, like this:

@Test
+public void validate_shouldMarkClientAsFraud() throws Exception {
+    // given:
+        MockMvcRequestSpecification request = given()
+                .header("Content-Type", "application/vnd.fraud.v1+json")
+                .body("{\"client.id\":\"1234567890\",\"loanAmount\":99999}");
+
+    // when:
+        ResponseOptions response = given().spec(request)
+                .put("/fraudcheck");
+
+    // then:
+        assertThat(response.statusCode()).isEqualTo(200);
+        assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*");
+    // and:
+        DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+        assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}");
+        assertThatJson(parsedJson).field("['rejection.reason']").isEqualTo("Amount too high");
+}

85.4 Step-by-step Guide to Consumer Driven Contracts (CDC)

Consider an example of Fraud Detection and the Loan Issuance process. The business +scenario is such that we want to issue loans to people but do not want them to steal from +us. The current implementation of our system grants loans to everybody.

Assume that Loan Issuance is a client to the Fraud Detection server. In the current +sprint, we must develop a new feature: if a client wants to borrow too much money, then +we mark the client as a fraud.

Technical remark - Fraud Detection has an artifact-id of http-server, while Loan +Issuance has an artifact-id of http-client, and both have a group-id of com.example.

Social remark - both client and server development teams need to communicate directly and +discuss changes while going through the process. CDC is all about communication.

The server +side code is available here and the +client code here.

[Tip]Tip

In this case, the producer owns the contracts. Physically, all the contract are +in the producer’s repository.

85.4.1 Technical note

If using the SNAPSHOT / Milestone / Release Candidate versions please add the +following section to your build:

Maven.  +

<repositories>
+	<repository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+</repositories>
+<pluginRepositories>
+	<pluginRepository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+</pluginRepositories>

+

Gradle.  +

repositories {
+	mavenCentral()
+	mavenLocal()
+	maven { url "https://repo.spring.io/snapshot" }
+	maven { url "https://repo.spring.io/milestone" }
+	maven { url "https://repo.spring.io/release" }
+}

+

85.4.2 Consumer side (Loan Issuance)

As a developer of the Loan Issuance service (a consumer of the Fraud Detection server), you might do the following steps:

  1. Start doing TDD by writing a test for your feature.
  2. Write the missing implementation.
  3. Clone the Fraud Detection service repository locally.
  4. Define the contract locally in the repo of Fraud Detection service.
  5. Add the Spring Cloud Contract Verifier plugin.
  6. Run the integration tests.
  7. File a pull request.
  8. Create an initial implementation.
  9. Take over the pull request.
  10. Write the missing implementation.
  11. Deploy your app.
  12. Work online.

Start doing TDD by writing a test for your feature.

@Test
+public void shouldBeRejectedDueToAbnormalLoanAmount() {
+	// given:
+	LoanApplication application = new LoanApplication(new Client("1234567890"),
+			99999);
+	// when:
+	LoanApplicationResult loanApplication = service.loanApplication(application);
+	// then:
+	assertThat(loanApplication.getLoanApplicationStatus())
+			.isEqualTo(LoanApplicationStatus.LOAN_APPLICATION_REJECTED);
+	assertThat(loanApplication.getRejectionReason()).isEqualTo("Amount too high");
+}

Assume that you have written a test of your new feature. If a loan application for a big +amount is received, the system should reject that loan application with some description.

Write the missing implementation.

At some point in time, you need to send a request to the Fraud Detection service. Assume +that you need to send the request containing the ID of the client and the amount the +client wants to borrow. You want to send it to the /fraudcheck url via the PUT method.

ResponseEntity<FraudServiceResponse> response =
+		restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
+				new HttpEntity<>(request, httpHeaders),
+				FraudServiceResponse.class);

For simplicity, the port of the Fraud Detection service is set to 8080, and the +application runs on 8090.

If you start the test at this point, it breaks, because no service currently runs on port +8080.

Clone the Fraud Detection service repository locally.

You can start by playing around with the server side contract. To do so, you must first +clone it.

$ git clone https://your-git-server.com/server-side.git local-http-server-repo

Define the contract locally in the repo of Fraud Detection service.

As a consumer, you need to define what exactly you want to achieve. You need to formulate +your expectations. To do so, write the following contract:

[Important]Important

Place the contract under src/test/resources/contracts/fraud folder. The fraud folder +is important because the producer’s test base class name references that folder.

Groovy DSL.  +

package contracts
+
+org.springframework.cloud.contract.spec.Contract.make {
+	request { // (1)
+		method 'PUT' // (2)
+		url '/fraudcheck' // (3)
+		body([ // (4)
+			   "client.id": $(regex('[0-9]{10}')),
+			   loanAmount: 99999
+		])
+		headers { // (5)
+			contentType('application/json')
+		}
+	}
+	response { // (6)
+		status 200 // (7)
+		body([ // (8)
+			   fraudCheckStatus: "FRAUD",
+			   "rejection.reason": "Amount too high"
+		])
+		headers { // (9)
+			contentType('application/json')
+		}
+	}
+}
+
+/*
+From the Consumer perspective, when shooting a request in the integration test:
+
+(1) - If the consumer sends a request
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the response will be sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` equal to `application/json`
+
+From the Producer perspective, in the autogenerated producer-side test:
+
+(1) - A request will be sent to the producer
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that will have a generated value that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the test will assert if the response has been sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` matching `application/json.*`
+ */

+

YAML.  +

request: # (1)
+  method: PUT # (2)
+  url: /fraudcheck # (3)
+  body: # (4)
+    "client.id": 1234567890
+    loanAmount: 99999
+  headers: # (5)
+    Content-Type: application/json
+  matchers:
+    body:
+      - path: $.['client.id'] # (6)
+        type: by_regex
+        value: "[0-9]{10}"
+response: # (7)
+  status: 200 # (8)
+  body:  # (9)
+    fraudCheckStatus: "FRAUD"
+    "rejection.reason": "Amount too high"
+  headers: # (10)
+    Content-Type: application/json;charset=UTF-8
+
+
+#From the Consumer perspective, when shooting a request in the integration test:
+#
+#(1) - If the consumer sends a request
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}`
+#(7) - then the response will be sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json`
+#
+#From the Producer perspective, in the autogenerated producer-side test:
+#
+#(1) - A request will be sent to the producer
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id` `1234567890`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(7) - then the test will assert if the response has been sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8`

+

The YML contract is quite straight-forward. However when you take a look at the Contract +written using a statically typed Groovy DSL - you might wonder what the +value(client(…​), server(…​)) parts are. By using this notation, Spring Cloud +Contract lets you define parts of a JSON block, a URL, etc., which are dynamic. In case +of an identifier or a timestamp, you need not hardcode a value. You want to allow some +different ranges of values. To enable ranges of values, you can set regular expressions +matching those values for the consumer side. You can provide the body by means of either +a map notation or String with interpolations. +Consult the docs +for more information. We highly recommend using the map notation!

[Tip]Tip

You must understand the map notation in order to set up contracts. Please read the +Groovy docs regarding JSON.

The previously shown contract is an agreement between two sides that:

  • if an HTTP request is sent with all of

    • a PUT method on the /fraudcheck endpoint,
    • a JSON body with a client.id that matches the regular expression [0-9]{10} and +loanAmount equal to 99999,
    • and a Content-Type header with a value of application/vnd.fraud.v1+json,

  • then an HTTP response is sent to the consumer that

    • has status 200,
    • contains a JSON body with the fraudCheckStatus field containing a value FRAUD and +the rejectionReason field having value Amount too high,
    • and a Content-Type header with a value of application/vnd.fraud.v1+json.

Once you are ready to check the API in practice in the integration tests, you need to +install the stubs locally.

Add the Spring Cloud Contract Verifier plugin.

We can add either a Maven or a Gradle plugin. In this example, you see how to add Maven. +First, add the Spring Cloud Contract BOM.

<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>${spring-cloud-dependencies.version}</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

Next, add the Spring Cloud Contract Verifier Maven plugin

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+</plugin>

Since the plugin was added, you get the Spring Cloud Contract Verifier features which, +from the provided contracts:

  • generate and run tests
  • produce and install stubs

You do not want to generate tests since you, as the consumer, want only to play with the +stubs. You need to skip the test generation and execution. When you execute:

$ cd local-http-server-repo
+$ ./mvnw clean install -DskipTests

In the logs, you see something like this:

[INFO] --- spring-cloud-contract-maven-plugin:1.0.0.BUILD-SNAPSHOT:generateStubs (default-generateStubs) @ http-server ---
+[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar
+[INFO]
+[INFO] --- maven-jar-plugin:2.6:jar (default-jar) @ http-server ---
+[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar
+[INFO]
+[INFO] --- spring-boot-maven-plugin:1.5.5.BUILD-SNAPSHOT:repackage (default) @ http-server ---
+[INFO]
+[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ http-server ---
+[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.jar
+[INFO] Installing /some/path/http-server/pom.xml to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.pom
+[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar

The following line is extremely important:

[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar

It confirms that the stubs of the http-server have been installed in the local +repository.

Run the integration tests.

In order to profit from the Spring Cloud Contract Stub Runner functionality of automatic +stub downloading, you must do the following in your consumer side project (Loan +Application service):

Add the Spring Cloud Contract BOM:

<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>${spring-cloud-dependencies.version}</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

Add the dependency to Spring Cloud Contract Stub Runner:

<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
+	<scope>test</scope>
+</dependency>

Annotate your test class with @AutoConfigureStubRunner. In the annotation, provide the +group-id and artifact-id for the Stub Runner to download the stubs of your +collaborators. (Optional step) Because you’re playing with the collaborators offline, you +can also provide the offline work switch.

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment=WebEnvironment.NONE)
+@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
+public class LoanApplicationServiceTests {

Now, when you run your tests, you see something like this:

2016-07-19 14:22:25.403  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Desired version is + - will try to resolve the latest version
+2016-07-19 14:22:25.438  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Resolved version is 0.0.1-SNAPSHOT
+2016-07-19 14:22:25.439  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Resolving artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT using remote repositories []
+2016-07-19 14:22:25.451  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Resolved artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar
+2016-07-19 14:22:25.465  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Unpacking stub from JAR [URI: file:/path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar]
+2016-07-19 14:22:25.475  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Unpacked file to [/var/folders/0p/xwq47sq106x1_g3dtv6qfm940000gq/T/contracts100276532569594265]
+2016-07-19 14:22:27.737  INFO 41050 --- [           main] o.s.c.c.stubrunner.StubRunnerExecutor    : All stubs are now running RunningStubs [namesAndPorts={com.example:http-server:0.0.1-SNAPSHOT:stubs=8080}]

This output means that Stub Runner has found your stubs and started a server for your app +with group id com.example, artifact id http-server with version 0.0.1-SNAPSHOT of +the stubs and with stubs classifier on port 8080.

File a pull request.

What you have done until now is an iterative process. You can play around with the +contract, install it locally, and work on the consumer side until the contract works as +you wish.

Once you are satisfied with the results and the test passes, publish a pull request to +the server side. Currently, the consumer side work is done.

85.4.3 Producer side (Fraud Detection server)

As a developer of the Fraud Detection server (a server to the Loan Issuance service):

Create an initial implementation.

As a reminder, you can see the initial implementation here:

@RequestMapping(value = "/fraudcheck", method = PUT)
+public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
+return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
+}

Take over the pull request.

$ git checkout -b contract-change-pr master
+$ git pull https://your-git-server.com/server-side-fork.git contract-change-pr

You must add the dependencies needed by the autogenerated tests:

<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-starter-contract-verifier</artifactId>
+	<scope>test</scope>
+</dependency>

In the configuration of the Maven plugin, pass the packageWithBaseClasses property

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+</plugin>
[Important]Important

This example uses "convention based" naming by setting the +packageWithBaseClasses property. Doing so means that the two last packages combine to +make the name of the base test class. In our case, the contracts were placed under +src/test/resources/contracts/fraud. Since you do not have two packages starting from +the contracts folder, pick only one, which should be fraud. Add the Base suffix and +capitalize fraud. That gives you the FraudBase test class name.

All the generated tests extend that class. Over there, you can set up your Spring Context +or whatever is necessary. In this case, use Rest Assured MVC to +start the server side FraudDetectionController.

package com.example.fraud;
+
+import org.junit.Before;
+
+import io.restassured.module.mockmvc.RestAssuredMockMvc;
+
+public class FraudBase {
+	@Before
+	public void setup() {
+		RestAssuredMockMvc.standaloneSetup(new FraudDetectionController(),
+				new FraudStatsController(stubbedStatsProvider()));
+	}
+
+	private StatsProvider stubbedStatsProvider() {
+		return fraudType -> {
+			switch (fraudType) {
+			case DRUNKS:
+				return 100;
+			case ALL:
+				return 200;
+			}
+			return 0;
+		};
+	}
+
+	public void assertThatRejectionReasonIsNull(Object rejectionReason) {
+		assert rejectionReason == null;
+	}
+}

Now, if you run the ./mvnw clean install, you get something like this:

Results :
+
+Tests in error:
+  ContractVerifierTest.validate_shouldMarkClientAsFraud:32 » IllegalState Parsed...

This error occurs because you have a new contract from which a test was generated and it +failed since you have not implemented the feature. The auto-generated test would look +like this:

@Test
+public void validate_shouldMarkClientAsFraud() throws Exception {
+    // given:
+        MockMvcRequestSpecification request = given()
+                .header("Content-Type", "application/vnd.fraud.v1+json")
+                .body("{\"client.id\":\"1234567890\",\"loanAmount\":99999}");
+
+    // when:
+        ResponseOptions response = given().spec(request)
+                .put("/fraudcheck");
+
+    // then:
+        assertThat(response.statusCode()).isEqualTo(200);
+        assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*");
+    // and:
+        DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+        assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}");
+        assertThatJson(parsedJson).field("['rejection.reason']").isEqualTo("Amount too high");
+}

If you used the Groovy DSL, you can see, all the producer() parts of the Contract that were present in the +value(consumer(…​), producer(…​)) blocks got injected into the test. +In case of using YAML, the same applied for the matchers sections of the response.

Note that, on the producer side, you are also doing TDD. The expectations are expressed +in the form of a test. This test sends a request to our own application with the URL, +headers, and body defined in the contract. It also is expecting precisely defined values +in the response. In other words, you have the red part of red, green, and +refactor. It is time to convert the red into the green.

Write the missing implementation.

Because you know the expected input and expected output, you can write the missing +implementation:

@RequestMapping(value = "/fraudcheck", method = PUT)
+public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
+if (amountGreaterThanThreshold(fraudCheck)) {
+	return new FraudCheckResult(FraudCheckStatus.FRAUD, AMOUNT_TOO_HIGH);
+}
+return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
+}

When you execute ./mvnw clean install again, the tests pass. Since the Spring Cloud +Contract Verifier plugin adds the tests to the generated-test-sources, you can +actually run those tests from your IDE.

Deploy your app.

Once you finish your work, you can deploy your change. First, merge the branch:

$ git checkout master
+$ git merge --no-ff contract-change-pr
+$ git push origin master

Your CI might run something like ./mvnw clean deploy, which would publish both the +application and the stub artifacts.

85.4.4 Consumer Side (Loan Issuance) Final Step

As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):

Merge branch to master.

$ git checkout master
+$ git merge --no-ff contract-change-pr

Work online.

Now you can disable the offline work for Spring Cloud Contract Stub Runner and indicate +where the repository with your stubs is located. At this moment the stubs of the server +side are automatically downloaded from Nexus/Artifactory. You can switch off the value of +the workOffline parameter in your annotation. The following code shows an example of +achieving the same thing by changing the properties.

stubrunner:
+  ids: 'com.example:http-server-dsl:+:stubs:8080'
+  repositoryRoot: https://repo.spring.io/libs-snapshot

That’s it!

85.5 Dependencies

The best way to add dependencies is to use the proper starter dependency.

For stub-runner, use spring-cloud-starter-stub-runner. When you use a plugin, add +spring-cloud-starter-contract-verifier.

85.6 Additional Links

Here are some resources related to Spring Cloud Contract Verifier and Stub Runner. Note +that some may be outdated, because the Spring Cloud Contract Verifier project is under +constant development.

85.6.1 Spring Cloud Contract video

You can check out the video from the Warsaw JUG about Spring Cloud Contract:

85.6.2 Readings

85.7 Samples

You can find some samples at +samples.

Prev Up Next
84. Spring Cloud Contract Home 86. Spring Cloud Contract FAQ
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88. Spring Cloud Contract Verifier Messaging
Prev Part XIII. Spring Cloud Contract Next

88. Spring Cloud Contract Verifier Messaging

Spring Cloud Contract Verifier lets you verify applications that uses messaging as a +means of communication. All of the integrations shown in this document work with Spring, +but you can also create one of your own and use that.

88.1 Integrations

You can use one of the following four integration configurations:

  • Apache Camel
  • Spring Integration
  • Spring Cloud Stream
  • Spring AMQP

Since we use Spring Boot, if you have added one of these libraries to the classpath, all +the messaging configuration is automatically set up.

[Important]Important

Remember to put @AutoConfigureMessageVerifier on the base class of your +generated tests. Otherwise, messaging part of Spring Cloud Contract Verifier does not +work.

[Important]Important

If you want to use Spring Cloud Stream, remember to add a dependency on +org.springframework.cloud:spring-cloud-stream-test-support, as shown here:

Maven.  +

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-stream-test-support</artifactId>
+    <scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile "org.springframework.cloud:spring-cloud-stream-test-support"

+

88.2 Manual Integration Testing

The main interface used by the tests is +org.springframework.cloud.contract.verifier.messaging.MessageVerifier. +It defines how to send and receive messages. You can create your own implementation to +achieve the same goal.

In a test, you can inject a ContractVerifierMessageExchange to send and receive +messages that follow the contract. Then add @AutoConfigureMessageVerifier to your test. +Here’s an example:

@RunWith(SpringTestRunner.class)
+@SpringBootTest
+@AutoConfigureMessageVerifier
+public static class MessagingContractTests {
+
+  @Autowired
+  private MessageVerifier verifier;
+  ...
+}
[Note]Note

If your tests require stubs as well, then @AutoConfigureStubRunner includes the +messaging configuration, so you only need the one annotation.

88.3 Publisher-Side Test Generation

Having the input or outputMessage sections in your DSL results in creation of tests +on the publisher’s side. By default, JUnit tests are created. However, there is also a +possibility to create Spock tests.

There are 3 main scenarios that we should take into consideration:

  • Scenario 1: There is no input message that produces an output message. The output +message is triggered by a component inside the application (for example, scheduler).
  • Scenario 2: The input message triggers an output message.
  • Scenario 3: The input message is consumed and there is no output message.
[Important]Important

The destination passed to messageFrom or sentTo can have different +meanings for different messaging implementations. For Stream and Integration it is +first resolved as a destination of a channel. Then, if there is no such destination +it is resolved as a channel name. For Camel, that’s a certain component (for example, +jms).

88.3.1 Scenario 1: No Input Message

Here is an example for Camel. For the given contract:

Groovy DSL.  +

def contractDsl = Contract.make {
+	label 'some_label'
+	input {
+		triggeredBy('bookReturnedTriggered()')
+	}
+	outputMessage {
+		sentTo('activemq:output')
+		body('''{ "bookName" : "foo" }''')
+		headers {
+			header('BOOK-NAME', 'foo')
+			messagingContentType(applicationJson())
+		}
+	}
+}

+

YAML.  +

label: some_label
+input:
+  triggeredBy: bookReturnedTriggered
+outputMessage:
+  sentTo: activemq:output
+  body:
+    bookName: foo
+  headers:
+    BOOK-NAME: foo
+    contentType: application/json

+

The following JUnit test is created:

'''
+ // when:
+  bookReturnedTriggered();
+
+ // then:
+  ContractVerifierMessage response = contractVerifierMessaging.receive("activemq:output");
+  assertThat(response).isNotNull();
+  assertThat(response.getHeader("BOOK-NAME")).isNotNull();
+  assertThat(response.getHeader("BOOK-NAME").toString()).isEqualTo("foo");
+  assertThat(response.getHeader("contentType")).isNotNull();
+  assertThat(response.getHeader("contentType").toString()).isEqualTo("application/json");
+ // and:
+  DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
+  assertThatJson(parsedJson).field("bookName").isEqualTo("foo");
+'''

And the following Spock test would be created:

'''
+ when:
+  bookReturnedTriggered()
+
+ then:
+  ContractVerifierMessage response = contractVerifierMessaging.receive('activemq:output')
+  assert response != null
+  response.getHeader('BOOK-NAME')?.toString()  == 'foo'
+  response.getHeader('contentType')?.toString()  == 'application/json'
+ and:
+  DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
+  assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
+
+'''

88.3.2 Scenario 2: Output Triggered by Input

Here is an example for Camel. For the given contract:

Groovy DSL.  +

def contractDsl = Contract.make {
+	label 'some_label'
+	input {
+		messageFrom('jms:input')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('jms:output')
+		body([
+				bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

+

YAML.  +

label: some_label
+input:
+  messageFrom: jms:input
+  messageBody:
+    bookName: 'foo'
+  messageHeaders:
+    sample: header
+outputMessage:
+  sentTo: jms:output
+  body:
+    bookName: foo
+  headers:
+    BOOK-NAME: foo

+

The following JUnit test is created:

'''
+// given:
+ ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+  "{\\"bookName\\":\\"foo\\"}"
+, headers()
+  .header("sample", "header"));
+
+// when:
+ contractVerifierMessaging.send(inputMessage, "jms:input");
+
+// then:
+ ContractVerifierMessage response = contractVerifierMessaging.receive("jms:output");
+ assertThat(response).isNotNull();
+ assertThat(response.getHeader("BOOK-NAME")).isNotNull();
+ assertThat(response.getHeader("BOOK-NAME").toString()).isEqualTo("foo");
+// and:
+ DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
+ assertThatJson(parsedJson).field("bookName").isEqualTo("foo");
+'''

And the following Spock test would be created:

"""\
+given:
+   ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+    '''{"bookName":"foo"}''',
+    ['sample': 'header']
+  )
+
+when:
+   contractVerifierMessaging.send(inputMessage, 'jms:input')
+
+then:
+   ContractVerifierMessage response = contractVerifierMessaging.receive('jms:output')
+   assert response !- null
+   response.getHeader('BOOK-NAME')?.toString()  == 'foo'
+and:
+   DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
+   assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
+"""

88.3.3 Scenario 3: No Output Message

Here is an example for Camel. For the given contract:

Groovy DSL.  +

def contractDsl = Contract.make {
+	label 'some_label'
+	input {
+		messageFrom('jms:delete')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+		assertThat('bookWasDeleted()')
+	}
+}

+

YAML.  +

label: some_label
+input:
+  messageFrom: jms:delete
+  messageBody:
+    bookName: 'foo'
+  messageHeaders:
+    sample: header
+  assertThat: bookWasDeleted()

+

The following JUnit test is created:

'''
+// given:
+ ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+	"{\\"bookName\\":\\"foo\\"}"
+, headers()
+	.header("sample", "header"));
+
+// when:
+ contractVerifierMessaging.send(inputMessage, "jms:delete");
+
+// then:
+ bookWasDeleted();
+'''

And the following Spock test would be created:

'''
+given:
+	 ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+		\'\'\'{"bookName":"foo"}\'\'\',
+		['sample': 'header']
+	)
+
+when:
+	 contractVerifierMessaging.send(inputMessage, 'jms:delete')
+
+then:
+	 noExceptionThrown()
+	 bookWasDeleted()
+'''

88.4 Consumer Stub Generation

Unlike the HTTP part, in messaging, we need to publish the Groovy DSL inside the JAR with +a stub. Then it is parsed on the consumer side and proper stubbed routes are created.

For more information, see +the +Stub Runner Messaging sections.

Maven.  +

<dependencies>
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-starter-stream-rabbit</artifactId>
+	</dependency>
+
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
+		<scope>test</scope>
+	</dependency>
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-stream-test-support</artifactId>
+		<scope>test</scope>
+	</dependency>
+</dependencies>
+
+<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>Edgware.BUILD-SNAPSHOT</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

+

Gradle.  +

ext {
+	contractsDir = file("mappings")
+	stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/")
+}
+
+// Automatically added by plugin:
+// copyContracts - copies contracts to the output folder from which JAR will be created
+// verifierStubsJar - JAR with a provided stub suffix
+// the presented publication is also added by the plugin but you can modify it as you wish
+
+publishing {
+	publications {
+		stubs(MavenPublication) {
+			artifactId "${project.name}-stubs"
+			artifact verifierStubsJar
+		}
+	}
+}

+

Prev Up Next
87. Spring Cloud Contract Verifier Setup Home 89. Spring Cloud Contract Stub Runner
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87. Spring Cloud Contract Verifier Setup
Prev Part XIII. Spring Cloud Contract Next

87. Spring Cloud Contract Verifier Setup

You can set up Spring Cloud Contract Verifier in the following ways:

87.1 Gradle Project

To learn how to set up the Gradle project for Spring Cloud Contract Verifier, read the +following sections:

87.1.1 Prerequisites

In order to use Spring Cloud Contract Verifier with WireMock, you muse use either a +Gradle or a Maven plugin.

[Warning]Warning

If you want to use Spock in your projects, you must add separately the +spock-core and spock-spring modules. Check Spock +docs for more information

87.1.2 Add Gradle Plugin with Dependencies

To add a Gradle plugin with dependencies, use code similar to this:

buildscript {
+	repositories {
+		mavenCentral()
+	}
+	dependencies {
+	    classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}"
+		classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}"
+	}
+}
+
+apply plugin: 'groovy'
+apply plugin: 'spring-cloud-contract'
+
+dependencyManagement {
+	imports {
+		mavenBom "org.springframework.cloud:spring-cloud-contract-dependencies:${verifier_version}"
+	}
+}
+
+dependencies {
+	testCompile 'org.codehaus.groovy:groovy-all:2.4.6'
+	// example with adding Spock core and Spock Spring
+	testCompile 'org.spockframework:spock-core:1.0-groovy-2.4'
+	testCompile 'org.spockframework:spock-spring:1.0-groovy-2.4'
+	testCompile 'org.springframework.cloud:spring-cloud-starter-contract-verifier'
+}

87.1.3 Gradle and Rest Assured 2.0

By default, Rest Assured 3.x is added to the classpath. However, to use Rest Assured 2.x +you can add it to the plugins classpath, as shown here:

buildscript {
+	repositories {
+		mavenCentral()
+	}
+	dependencies {
+	    classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}"
+		classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}"
+		classpath "com.jayway.restassured:rest-assured:2.5.0"
+		classpath "com.jayway.restassured:spring-mock-mvc:2.5.0"
+	}
+}
+
+depenendencies {
+    // all dependencies
+    // you can exclude rest-assured from spring-cloud-contract-verifier
+    testCompile "com.jayway.restassured:rest-assured:2.5.0"
+    testCompile "com.jayway.restassured:spring-mock-mvc:2.5.0"
+}

That way, the plugin automatically sees that Rest Assured 2.x is present on the classpath +and modifies the imports accordingly.

87.1.4 Snapshot Versions for Gradle

Add the additional snapshot repository to your build.gradle to use snapshot versions, +which are automatically uploaded after every successful build, as shown here:

buildscript {
+	repositories {
+		mavenCentral()
+		mavenLocal()
+		maven { url "https://repo.spring.io/snapshot" }
+		maven { url "https://repo.spring.io/milestone" }
+		maven { url "https://repo.spring.io/release" }
+	}
+}

87.1.5 Add stubs

By default, Spring Cloud Contract Verifier is looking for stubs in the +src/test/resources/contracts directory.

The directory containing stub definitions is treated as a class name, and each stub +definition is treated as a single test. Spring Cloud Contract Verifier assumes that it +contains at least one level of directories that are to be used as the test class name. +If more than one level of nested directories is present, all except the last one is used +as the package name. For example, with following structure:

src/test/resources/contracts/myservice/shouldCreateUser.groovy
+src/test/resources/contracts/myservice/shouldReturnUser.groovy

Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService +with two methods:

  • shouldCreateUser()
  • shouldReturnUser()

87.1.6 Run the Plugin

The plugin registers itself to be invoked before a check task. If you want it to be +part of your build process, you need to do nothing more. If you just want to generate +tests, invoke the generateContractTests task.

87.1.7 Default Setup

The default Gradle Plugin setup creates the following Gradle part of the build (in +pseudocode):

contracts {
+    targetFramework = 'JUNIT'
+    testMode = 'MockMvc'
+    generatedTestSourcesDir = project.file("${project.buildDir}/generated-test-sources/contracts")
+    contractsDslDir = "${project.rootDir}/src/test/resources/contracts"
+    basePackageForTests = 'org.springframework.cloud.verifier.tests'
+    stubsOutputDir = project.file("${project.buildDir}/stubs")
+
+    // the following properties are used when you want to provide where the JAR with contract lays
+    contractDependency {
+        stringNotation = ''
+    }
+    contractsPath = ''
+    contractsWorkOffline = false
+    contractRepository {
+        cacheDownloadedContracts(true)
+    }
+}
+
+tasks.create(type: Jar, name: 'verifierStubsJar', dependsOn: 'generateClientStubs') {
+    baseName = project.name
+    classifier = contracts.stubsSuffix
+    from contractVerifier.stubsOutputDir
+}
+
+project.artifacts {
+    archives task
+}
+
+tasks.create(type: Copy, name: 'copyContracts') {
+    from contracts.contractsDslDir
+    into contracts.stubsOutputDir
+}
+
+verifierStubsJar.dependsOn 'copyContracts'
+
+publishing {
+    publications {
+        stubs(MavenPublication) {
+            artifactId project.name
+            artifact verifierStubsJar
+        }
+    }
+}

87.1.8 Configure Plugin

To change the default configuration, add a contracts snippet to your Gradle config, as +shown here:

contracts {
+	testMode = 'MockMvc'
+	baseClassForTests = 'org.mycompany.tests'
+	generatedTestSourcesDir = project.file('src/generatedContract')
+}

87.1.9 Configuration Options

  • testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, +which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to +Explicit for real HTTP calls.
  • imports: Creates an array with imports that should be included in generated tests +(for example ['org.myorg.Matchers']). By default, it creates an empty array.
  • staticImports: Creates an array with static imports that should be included in +generated tests(for example ['org.myorg.Matchers.*']). By default, it creates an empty +array.
  • basePackageForTests: Specifies the base package for all generated tests. If not set, +the value is picked from baseClassForTests’s package and from `packageWithBaseClasses. +If neither of these values are set, then the value is set to +org.springframework.cloud.contract.verifier.tests.
  • baseClassForTests: Creates a base class for all generated tests. By default, if you +use Spock classes, the class is spock.lang.Specification.
  • packageWithBaseClasses: Defines a package where all the base classes reside. This +setting takes precedence over baseClassForTests.
  • baseClassMappings: Explicitly maps a contract package to a FQN of a base class. This +setting takes precedence over packageWithBaseClasses and baseClassForTests.
  • ruleClassForTests: Specifies a rule that should be added to the generated test +classes.
  • ignoredFiles: Uses an Antmatcher to allow defining stub files for which processing +should be skipped. By default, it is an empty array.
  • contractsDslDir: Specifies the directory containing contracts written using the +GroovyDSL. By default, its value is $rootDir/src/test/resources/contracts.
  • generatedTestSourcesDir: Specifies the test source directory where tests generated +from the Groovy DSL should be placed. By default its value is +$buildDir/generated-test-sources/contractVerifier.
  • stubsOutputDir: Specifies the directory where the generated WireMock stubs from +the Groovy DSL should be placed.
  • targetFramework: Specifies the target test framework to be used. Currently, Spock and +JUnit are supported with JUnit being the default framework.

The following properties are used when you want to specify the location of the JAR +containing the contracts: +* contractDependency: Specifies the Dependency that provides +groupid:artifactid:version:classifier coordinates. You can use the contractDependency +closure to set it up. +* contractsPath: Specifies the path to the jar. If contract dependencies are + downloaded, the path defaults to groupid/artifactid where groupid is slash + separated. Otherwise, it scans contracts under the provided directory. +* contractsWorkOffline: Specifies whether to download the dependencies each time, so +that you can work online. In other words, it specifies whether to reuses the local Maven +repo.

87.1.10 Single Base Class for All Tests

When using Spring Cloud Contract Verifier in default MockMvc, you need to create a base +specification for all generated acceptance tests. In this class, you need to point to an +endpoint, which should be verified.

abstract class BaseMockMvcSpec extends Specification {
+
+	def setup() {
+		RestAssuredMockMvc.standaloneSetup(new PairIdController())
+	}
+
+	void isProperCorrelationId(Integer correlationId) {
+		assert correlationId == 123456
+	}
+
+	void isEmpty(String value) {
+		assert value == null
+	}
+
+}

If you use Explicit mode, you can use a base class to initialize the whole tested app +as you might see in regular integration tests. If you use the JAXRSCLIENT mode, this +base class should also contain a protected WebTarget webTarget field. Right now, the +only option to test the JAX-RS API is to start a web server.

87.1.11 Different Base Classes for Contracts

If your base classes differ between contracts, you can tell the Spring Cloud Contract +plugin which class should get extended by the autogenerated tests. You have two options:

  • Follow a convention by providing the packageWithBaseClasses
  • Provide explicit mapping via baseClassMappings

By Convention

The convention is such that if you have a contract under (for example) +src/test/resources/contract/foo/bar/baz/ and set the value of the +packageWithBaseClasses property to com.example.base, then Spring Cloud Contract +Verifier assumes that there is a BarBazBase class under the com.example.base package. +In other words, the system takes the last two parts of the package, if they exist, and +forms a class with a Base suffix. This rule takes precedence over baseClassForTests. +Here is an example of how it works in the contracts closure:

packageWithBaseClasses = 'com.example.base'

By Mapping

You can manually map a regular expression of the contract’s package to fully qualified +name of the base class for the matched contract. You have to provide a list called +baseClassMappings that consists baseClassMapping objects that takes a +contractPackageRegex to baseClassFQN mapping. Consider the following example:

baseClassForTests = "com.example.FooBase"
+baseClassMappings {
+	baseClassMapping('.*/com/.*', 'com.example.ComBase')
+	baseClassMapping('.*/bar/.*':'com.example.BarBase')
+}

Let’s assume that you have contracts under + - src/test/resources/contract/com/ + - src/test/resources/contract/foo/

By providing the baseClassForTests, we have a fallback in case mapping did not succeed. +(You could also provide the packageWithBaseClasses as a fallback.) That way, the tests +generated from src/test/resources/contract/com/ contracts extend the +com.example.ComBase, whereas the rest of the tests extend com.example.FooBase.

87.1.12 Invoking Generated Tests

To ensure that the provider side is compliant with defined contracts, you need to invoke:

./gradlew generateContractTests test

87.1.13 Spring Cloud Contract Verifier on the Consumer Side

In a consuming service, you need to configure the Spring Cloud Contract Verifier plugin +in exactly the same way as in case of provider. If you do not want to use Stub Runner +then you need to copy contracts stored in src/test/resources/contracts and generate +WireMock JSON stubs using:

./gradlew generateClientStubs
[Note]Note

The stubsOutputDir option has to be set for stub generation to work.

When present, JSON stubs can be used in automated tests of consuming a service.

@ContextConfiguration(loader == SpringApplicationContextLoader, classes == Application)
+class LoanApplicationServiceSpec extends Specification {
+
+ @ClassRule
+ @Shared
+ WireMockClassRule wireMockRule == new WireMockClassRule()
+
+ @Autowired
+ LoanApplicationService sut
+
+ def 'should successfully apply for loan'() {
+   given:
+ 	LoanApplication application =
+			new LoanApplication(client: new Client(clientPesel: '12345678901'), amount: 123.123)
+   when:
+	LoanApplicationResult loanApplication == sut.loanApplication(application)
+   then:
+	loanApplication.loanApplicationStatus == LoanApplicationStatus.LOAN_APPLIED
+	loanApplication.rejectionReason == null
+ }
+}

LoanApplication makes a call to FraudDetection service. This request is handled by a +WireMock server configured with stubs generated by Spring Cloud Contract Verifier.

87.2 Maven Project

To learn how to set up the Maven project for Spring Cloud Contract Verifier, read the +following sections:

87.2.1 Add maven plugin

Add the Spring Cloud Contract BOM in a fashion similar to this:

<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>${spring-cloud-dependencies.version}</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

Next, add the Spring Cloud Contract Verifier Maven plugin:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+</plugin>

You can read more in the +Spring +Cloud Contract Maven Plugin Documentation.

87.2.2 Maven and Rest Assured 2.0

By default, Rest Assured 3.x is added to the classpath. However, you can use Rest +Assured 2.x by adding it to the plugins classpath, as shown here:

<plugin>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+    <version>${spring-cloud-contract.version}</version>
+    <extensions>true</extensions>
+    <configuration>
+        <packageWithBaseClasses>com.example</packageWithBaseClasses>
+    </configuration>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.cloud</groupId>
+            <artifactId>spring-cloud-contract-verifier</artifactId>
+            <version>${spring-cloud-contract.version}</version>
+        </dependency>
+        <dependency>
+           <groupId>com.jayway.restassured</groupId>
+           <artifactId>rest-assured</artifactId>
+           <version>2.5.0</version>
+           <scope>compile</scope>
+        </dependency>
+        <dependency>
+           <groupId>com.jayway.restassured</groupId>
+           <artifactId>spring-mock-mvc</artifactId>
+           <version>2.5.0</version>
+           <scope>compile</scope>
+        </dependency>
+    </dependencies>
+</plugin>
+
+<dependencies>
+    <!-- all dependencies -->
+    <!-- you can exclude rest-assured from spring-cloud-contract-verifier -->
+    <dependency>
+       <groupId>com.jayway.restassured</groupId>
+       <artifactId>rest-assured</artifactId>
+       <version>2.5.0</version>
+       <scope>test</scope>
+    </dependency>
+    <dependency>
+       <groupId>com.jayway.restassured</groupId>
+       <artifactId>spring-mock-mvc</artifactId>
+       <version>2.5.0</version>
+       <scope>test</scope>
+    </dependency>
+</dependencies>

That way, the plugin automatically sees that Rest Assured 3.x is present on the classpath +and modifies the imports accordingly.

87.2.3 Snapshot versions for Maven

For Snapshot and Milestone versions, you have to add the following section to your +pom.xml, as shown here:

<repositories>
+	<repository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+</repositories>
+<pluginRepositories>
+	<pluginRepository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+</pluginRepositories>

87.2.4 Add stubs

By default, Spring Cloud Contract Verifier is looking for stubs in the +src/test/resources/contracts directory. The directory containing stub definitions is +treated as a class name, and each stub definition is treated as a single test. We assume +that it contains at least one directory to be used as test class name. If there is more +than one level of nested directories, all except the last one is used as package name. +For example, with following structure:

src/test/resources/contracts/myservice/shouldCreateUser.groovy
+src/test/resources/contracts/myservice/shouldReturnUser.groovy

Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService +with two methods

  • shouldCreateUser()
  • shouldReturnUser()

87.2.5 Run plugin

The plugin goal generateTests is assigned to be invoked in the phase called +generate-test-sources. If you want it to be part of your build process, you need not do +anything. If you just want to generate tests, invoke the generateTests goal.

87.2.6 Configure plugin

To change the default configuration, just add a configuration section to the plugin +definition or the execution definition, as shown here:

<plugin>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+    <executions>
+        <execution>
+            <goals>
+                <goal>convert</goal>
+                <goal>generateStubs</goal>
+                <goal>generateTests</goal>
+            </goals>
+        </execution>
+    </executions>
+    <configuration>
+        <basePackageForTests>org.springframework.cloud.verifier.twitter.place</basePackageForTests>
+        <baseClassForTests>org.springframework.cloud.verifier.twitter.place.BaseMockMvcSpec</baseClassForTests>
+    </configuration>
+</plugin>

87.2.7 Configuration Options

  • testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, +which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to +Explicit for real HTTP calls.
  • basePackageForTests: Specifies the base package for all generated tests. If not set, +the value is picked from baseClassForTests’s package and from `packageWithBaseClasses. +If neither of these values are set, then the value is set to +org.springframework.cloud.contract.verifier.tests.
  • ruleClassForTests: Specifies a rule that should be added to the generated test +classes.
  • baseClassForTests: Creates a base class for all generated tests. By default, if you +use Spock classes, the class is spock.lang.Specification.
  • contractsDirectory: Specifies a directory containing contracts written with the +GroovyDSL. The default directory is /src/test/resources/contracts.
  • testFramework: Specifies the target test framework to be used. Currently, Spock and +JUnit are supported with JUnit being the default framework
  • packageWithBaseClasses: Defines a package where all the base classes reside. This +setting takes precedence over baseClassForTests. The convention is such that, if you +have a contract under (for example) src/test/resources/contract/foo/bar/baz/ and set +the value of the packageWithBaseClasses property to com.example.base, then Spring +Cloud Contract Verifier assumes that there is a BarBazBase class under the +com.example.base package. In other words, the system takes the last two parts of the +package, if they exist, and forms a class with a Base suffix.
  • baseClassMappings: Specifies a list of base class mappings that provide +contractPackageRegex, which is checked against the package where the contract is +located, and baseClassFQN, which maps to the fully qualified name of the base class for +the matched contract. For example, if you have a contract under +src/test/resources/contract/foo/bar/baz/ and map the property +.* → com.example.base.BaseClass, then the test class generated from these contracts +extends com.example.base.BaseClass. This setting takes precedence over +packageWithBaseClasses and baseClassForTests.

If you want to download your contract definitions from a Maven repository, you can use +the following options:

  • contractDependency: The contract dependency that contains all the packaged contracts.
  • contractsPath: The path to the concrete contracts in the JAR with packaged contracts. +Defaults to groupid/artifactid where gropuid is slash separated.
  • contractsWorkOffline: Dictates whether the dependencies should be downloaded or the +local Maven artifacts should be reused.
  • contractsRepositoryUrl: URL to a repo with the artifacts that have contracts. If it is not provided, +use the current Maven ones.
  • contractsRepositoryUsername: The user name to be used to connect to the repo with contracts.
  • contractsRepositoryPassword: The password to be used to connect to the repo with contracts.
  • contractsRepositoryProxyHost: The proxy host to be used to connect to the repo with contracts.
  • contractsRepositoryProxyPort: The proxy port to be used to connect to the repo with contracts.

We cache only non-snapshot, explicitly provided versions (for example ++ or 1.0.0.BUILD-SNAPSHOT won’t get cached). By default, this feature is turned on.

87.2.8 Single Base Class for All Tests

When using Spring Cloud Contract Verifier in default MockMvc, you need to create a base +specification for all generated acceptance tests. In this class, you need to point to an +endpoint, which should be verified.

package org.mycompany.tests
+
+import org.mycompany.ExampleSpringController
+import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc
+import spock.lang.Specification
+
+class  MvcSpec extends Specification {
+  def setup() {
+   RestAssuredMockMvc.standaloneSetup(new ExampleSpringController())
+  }
+}

If you use Explicit mode, you can use a base class to initialize the whole tested app +similarly, as you might find in regular integration tests. If you use the JAXRSCLIENT +mode, this base class should also contain a protected WebTarget webTarget field. Right +now, the only option to test the JAX-RS API is to start a web server.

87.2.9 Different base classes for contracts

If your base classes differ between contracts, you can tell the Spring Cloud Contract +plugin which class should get extended by the autogenerated tests. You have two options:

  • Follow a convention by providing the packageWithBaseClasses
  • provide explicit mapping via baseClassMappings

By Convention

The convention is such that if you have a contract under (for example) +src/test/resources/contract/foo/bar/baz/ and set the value of the +packageWithBaseClasses property to com.example.base, then Spring Cloud Contract +Verifier assumes that there is a BarBazBase class under the com.example.base package. +In other words, the system takes the last two parts of the package, if they exist, and +forms a class with a Base suffix. This rule takes precedence over baseClassForTests. +Here is an example of how it works in the contracts closure:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<configuration>
+		<packageWithBaseClasses>hello</packageWithBaseClasses>
+	</configuration>
+</plugin>

By Mapping

You can manually map a regular expression of the contract’s package to fully qualified +name of the base class for the matched contract. You have to provide a list called +baseClassMappings that consists baseClassMapping objects that takes a +contractPackageRegex to baseClassFQN mapping. Consider the following example:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<configuration>
+		<baseClassForTests>com.example.FooBase</baseClassForTests>
+		<baseClassMappings>
+			<baseClassMapping>
+				<contractPackageRegex>.*com.*</contractPackageRegex>
+				<baseClassFQN>com.example.TestBase</baseClassFQN>
+			</baseClassMapping>
+		</baseClassMappings>
+	</configuration>
+</plugin>

Assume that you have contracts under these two locations: +* src/test/resources/contract/com/ +* src/test/resources/contract/foo/

By providing the baseClassForTests, we have a fallback in case mapping did not succeed. +(You can also provide the packageWithBaseClasses as a fallback.) That way, the tests +generated from src/test/resources/contract/com/ contracts extend the +com.example.ComBase, whereas the rest of the tests extend com.example.FooBase.

87.2.10 Invoking generated tests

The Spring Cloud Contract Maven Plugin generates verification code in a directory called +/generated-test-sources/contractVerifier and attaches this directory to testCompile +goal.

For Groovy Spock code, use the following:

<plugin>
+	<groupId>org.codehaus.gmavenplus</groupId>
+	<artifactId>gmavenplus-plugin</artifactId>
+	<version>1.5</version>
+	<executions>
+		<execution>
+			<goals>
+				<goal>testCompile</goal>
+			</goals>
+		</execution>
+	</executions>
+	<configuration>
+		<testSources>
+			<testSource>
+				<directory>${project.basedir}/src/test/groovy</directory>
+				<includes>
+					<include>**/*.groovy</include>
+				</includes>
+			</testSource>
+			<testSource>
+				<directory>${project.build.directory}/generated-test-sources/contractVerifier</directory>
+				<includes>
+					<include>**/*.groovy</include>
+				</includes>
+			</testSource>
+		</testSources>
+	</configuration>
+</plugin>

To ensure that provider side is compliant with defined contracts, you need to invoke +mvn generateTest test.

87.2.11 Maven Plugin and STS

If you see the following exception while using STS:

STS Exception

When you click on the error marker you should see something like this:

 plugin:1.1.0.M1:convert:default-convert:process-test-resources) org.apache.maven.plugin.PluginExecutionException: Execution default-convert of goal org.springframework.cloud:spring-
+ cloud-contract-maven-plugin:1.1.0.M1:convert failed. at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145) at
+ org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331) at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362) at
+...
+ org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.lang.NullPointerException at
+ org.eclipse.m2e.core.internal.builder.plexusbuildapi.EclipseIncrementalBuildContext.hasDelta(EclipseIncrementalBuildContext.java:53) at
+ org.sonatype.plexus.build.incremental.ThreadBuildContext.hasDelta(ThreadBuildContext.java:59) at

In order to fix this issue, provide the following section in your pom.xml:

<build>
+    <pluginManagement>
+        <plugins>
+            <!--This plugin's configuration is used to store Eclipse m2e settings
+                only. It has no influence on the Maven build itself. -->
+            <plugin>
+                <groupId>org.eclipse.m2e</groupId>
+                <artifactId>lifecycle-mapping</artifactId>
+                <version>1.0.0</version>
+                <configuration>
+                    <lifecycleMappingMetadata>
+                        <pluginExecutions>
+                             <pluginExecution>
+                                <pluginExecutionFilter>
+                                    <groupId>org.springframework.cloud</groupId>
+                                    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+                                    <versionRange>[1.0,)</versionRange>
+                                    <goals>
+                                        <goal>convert</goal>
+                                    </goals>
+                                </pluginExecutionFilter>
+                                <action>
+                                    <execute />
+                                </action>
+                             </pluginExecution>
+                        </pluginExecutions>
+                    </lifecycleMappingMetadata>
+                </configuration>
+            </plugin>
+        </plugins>
+    </pluginManagement>
+</build>

87.3 Stubs and Transitive Dependencies

The Maven and Gradle plugin that add the tasks that create the stubs jar for you. One +problem that arises is that, when reusing the stubs, you can mistakenly import all of +that stub’s dependencies. When building a Maven artifact, even though you have a couple +of different jars, all of them share one pom:

├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar
+├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar.sha1
+├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar
+├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar.sha1
+├── github-webhook-0.0.1.BUILD-SNAPSHOT.jar
+├── github-webhook-0.0.1.BUILD-SNAPSHOT.pom
+├── github-webhook-0.0.1.BUILD-SNAPSHOT-stubs.jar
+├── ...
+└── ...

There are three possibilities of working with those dependencies so as not to have any +issues with transitive dependencies:

  • Mark all application dependencies as optional
  • Create a separate artifactid for the stubs
  • Exclude dependencies on the consumer side

Mark all application dependencies as optional

If, in the github-webhook application, you mark all of your dependencies as optional, +when you include the github-webhook stubs in another application (or when that +dependency gets downloaded by Stub Runner) then, since all of the dependencies are +optional, they will not get downloaded.

Create a separate artifactid for the stubs

If you create a separate artifactid, then you can set it up in whatever way you wish. +For example, you might decide to have no dependencies at all.

Exclude dependencies on the consumer side

As a consumer, if you add the stub dependency to your classpath, you can explicitly +exclude the unwanted dependencies.

87.4 CI Server setup

When fetching stubs / contracts in a CI, shared environment, what might happen is that +both the producer and the consumer reuse the same local Maven repository. Due to this, +the framework, responsible for downloading a stub JAR from remote location, +can’t decide which JAR should be picked, local or remote one. That caused +the "The artifact was found in the local repository but you have explicitly +stated that it should be downloaded from a remote one" exception +and failed the build.

For such cases we’re introducing the property mechanism:

  • via stubrunner.snapshot-check-skip system property
  • via STUBRUNNER_SNAPSHOT_CHECK_SKIP environment variable

if either of these values is set to true, then the stub downloader will not +verify the origin of the downloaded JAR.

87.5 Scenarios

You can handle scenarios with Spring Cloud Contract Verifier. All you need to do is to +stick to the proper naming convention while creating your contracts. The convention +requires including an order number followed by an underscore. This will work regardles + of whether you’re working with YAML or Groovy. Example:

my_contracts_dir\
+  scenario1\
+    1_login.groovy
+    2_showCart.groovy
+    3_logout.groovy

Such a tree causes Spring Cloud Contract Verifier to generate WireMock’s scenario with a +name of scenario1 and the three following steps:

  1. login marked as Started pointing to…​
  2. showCart marked as Step1 pointing to…​
  3. logout marked as Step2 which will close the scenario.

More details about WireMock scenarios can be found at +https://wiremock.org/stateful-behaviour.html

Spring Cloud Contract Verifier also generates tests with a guaranteed order of execution.

87.6 Docker Project

We’re publishing a springcloud/spring-cloud-contract Docker image +that contains a project that will generate tests and execute them in EXPLICIT mode +against a running application.

[Tip]Tip

The EXPLICIT mode means that the tests generated from contracts will send +real requests and not the mocked ones.

87.6.1 Short intro to Maven, JARs and Binary storage

Since the Docker image can be used by non JVM projects, it’s good to +explain the basic terms behind Spring Cloud Contract packaging defaults.

Part of the following definitions were taken from the Maven Glossary

  • Project: Maven thinks in terms of projects. Everything that you +will build are projects. Those projects follow a well defined +“Project Object Model”. Projects can depend on other projects, +in which case the latter are called “dependencies”. A project may +consistent of several subprojects, however these subprojects are still +treated equally as projects.
  • Artifact: An artifact is something that is either produced or used +by a project. Examples of artifacts produced by Maven for a project +include: JARs, source and binary distributions. Each artifact +is uniquely identified by a group id and an artifact ID which is +unique within a group.
  • JAR: JAR stands for Java ARchive. It’s a format based on +the ZIP file format. Spring Cloud Contract packages the contracts and generated +stubs in a JAR file.
  • GroupId: A group ID is a universally unique identifier for a project. +While this is often just the project name (eg. commons-collections), +it is helpful to use a fully-qualified package name to distinguish it +from other projects with a similar name (eg. org.apache.maven). +Typically, when published to the Artifact Manager, the GroupId will get +slash separated and form part of the URL. E.g. for group id com.example +and artifact id application would be /com/example/application/.
  • Classifier: The Maven dependency notation looks as follows: +groupId:artifactId:version:classifier. The classifier is additional suffix +passed to the dependency. E.g. stubs, sources. The same dependency +e.g. com.example:application can produce multiple artifacts that +differ from each other with the classifier.
  • Artifact manager: When you generate binaries / sources / packages, you would +like them to be available for others to download / reference or reuse. In case +of the JVM world those artifacts would be JARs, for Ruby these are gems +and for Docker those would be Docker images. You can store those artifacts +in a manager. Examples of such managers can be Artifactory +or Nexus.

87.6.2 How it works

The image searches for contracts under the /contracts folder. +The output from running the tests will be available under +/spring-cloud-contract/build folder (it’s useful for debugging +purposes).

It’s enough for you to mount your contracts, pass the environment variables + and the image will:

  • generate the contract tests
  • execute the tests against the provided URL
  • generate the WireMock stubs
  • (optional - turned on by default) publish the stubs to a Artifact Manager

Environment Variables

The Docker image requires some environment variables to point to +your running application, to the Artifact manager instance etc.

  • PROJECT_GROUP - your project’s group id. Defaults to com.example
  • PROJECT_VERSION - your project’s version. Defaults to 0.0.1-SNAPSHOT
  • PROJECT_NAME - artifact id. Defaults to example
  • REPO_WITH_BINARIES_URL - URL of your Artifact Manager. Defaults to http://localhost:8081/artifactory/libs-release-local +which is the default URL of Artifactory running locally
  • REPO_WITH_BINARIES_USERNAME - (optional) username when the Artifact Manager is secured
  • REPO_WITH_BINARIES_PASSWORD - (optional) password when the Artifact Manager is secured
  • PUBLISH_ARTIFACTS - if set to true then will publish artifact to binary storage. Defaults to true.

These environment variables are used when contracts lay in an external repository. To enable +this feature you must set the EXTERNAL_CONTRACTS_ARTIFACT_ID environment variable.

  • EXTERNAL_CONTRACTS_GROUP_ID - group id of the project with contracts. Defaults to com.example
  • EXTERNAL_CONTRACTS_ARTIFACT_ID- artifact id of the project with contracts.
  • EXTERNAL_CONTRACTS_CLASSIFIER- classifier of the project with contracts. Empty by default
  • EXTERNAL_CONTRACTS_VERSION - version of the project with contracts. Defaults to +, equivalent to picking the latest
  • EXTERNAL_CONTRACTS_REPO_WITH_BINARIES_URL - URL of your Artifact Manager. Defaults to value of REPO_WITH_BINARIES_URL env var. +If that’s not set, defaults to http://localhost:8081/artifactory/libs-release-local +which is the default URL of Artifactory running locally
  • EXTERNAL_CONTRACTS_PATH - path to contracts for the given project, inside the project with contracts. +Defaults to slash separated EXTERNAL_CONTRACTS_GROUP_ID concatenated with / and EXTERNAL_CONTRACTS_ARTIFACT_ID. E.g. +for group id foo.bar and artifact id baz, would result in foo/bar/baz contracts path.
  • EXTERNAL_CONTRACTS_WORK_OFFLINE - if set to true then will retrieve artifact with contracts +from the container’s .m2. Mount your local .m2 as a volume available at the container’s /root/.m2 path. +You must not set both EXTERNAL_CONTRACTS_WORK_OFFLINE and EXTERNAL_CONTRACTS_REPO_WITH_BINARIES_URL.

These environment variables are used when tests are executed:

  • APPLICATION_BASE_URL - url against which tests should be executed. +Remember that it has to be accessible from the Docker container (e.g. localhost +will not work)
  • APPLICATION_USERNAME - (optional) username for basic authentication to your application
  • APPLICATION_PASSWORD - (optional) password for basic authentication to your application

87.6.3 Example of usage

Let’s take a look at a simple MVC application

$ git clone https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs
+$ cd bookstore

The contracts are available under /contracts folder.

87.6.4 Server side (nodejs)

Since we want to run tests, we could just execute:

$ npm test

however, for learning purposes, let’s split it into pieces:

# Stop docker infra (nodejs, artifactory)
+$ ./stop_infra.sh
+# Start docker infra (nodejs, artifactory)
+$ ./setup_infra.sh
+
+# Kill & Run app
+$ pkill -f "node app"
+$ nohup node app &
+
+# Prepare environment variables
+$ SC_CONTRACT_DOCKER_VERSION="..."
+$ APP_IP="192.168.0.100"
+$ APP_PORT="3000"
+$ ARTIFACTORY_PORT="8081"
+$ APPLICATION_BASE_URL="http://${APP_IP}:${APP_PORT}"
+$ ARTIFACTORY_URL="http://${APP_IP}:${ARTIFACTORY_PORT}/artifactory/libs-release-local"
+$ CURRENT_DIR="$( pwd )"
+$ CURRENT_FOLDER_NAME=${PWD##*/}
+$ PROJECT_VERSION="0.0.1.RELEASE"
+
+# Execute contract tests
+$ docker run  --rm -e "APPLICATION_BASE_URL=${APPLICATION_BASE_URL}" -e "PUBLISH_ARTIFACTS=true" -e "PROJECT_NAME=${CURRENT_FOLDER_NAME}" -e "REPO_WITH_BINARIES_URL=${ARTIFACTORY_URL}" -e "PROJECT_VERSION=${PROJECT_VERSION}" -v "${CURRENT_DIR}/contracts/:/contracts:ro" -v "${CURRENT_DIR}/node_modules/spring-cloud-contract/output:/spring-cloud-contract-output/" springcloud/spring-cloud-contract:"${SC_CONTRACT_DOCKER_VERSION}"
+
+# Kill app
+$ pkill -f "node app"

What will happen is that via bash scripts:

  • infrastructure will be set up (MongoDb, Artifactory). +In real life scenario you would just run the NodeJS application +with mocked database. In this example we want to show how we can +benefit from Spring Cloud Contract in no time.

  • due to those constraints the contracts also represent the +stateful situation

    • first request is a POST that causes data to get inserted to the database
    • second request is a GET that returns a list of data with 1 previously inserted element
  • the NodeJS application will be started (on port 3000)

  • contract tests will be generated via Docker and tests +will be executed against the running application

    • the contracts will be taken from /contracts folder.
    • the output of the test execution is available under +node_modules/spring-cloud-contract/output.
  • the stubs will be uploaded to Artifactory. You can check them out +under http://localhost:8081/artifactory/libs-release-local/com/example/bookstore/0.0.1.RELEASE/ . +The stubs will be here http://localhost:8081/artifactory/libs-release-local/com/example/bookstore/0.0.1.RELEASE/bookstore-0.0.1.RELEASE-stubs.jar.

To see how the client side looks like check out the Section 89.9, “Stub Runner Docker” section.

Prev Up Next
86. Spring Cloud Contract FAQ Home 88. Spring Cloud Contract Verifier Messaging
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94. Spring Cloud Contract WireMock
Prev Part XIII. Spring Cloud Contract Next

94. Spring Cloud Contract WireMock

The Spring Cloud Contract WireMock modules let you use WireMock in a +Spring Boot application. Check out the +samples +for more details.

If you have a Spring Boot application that uses Tomcat as an embedded server (which is +the default with spring-boot-starter-web), you can add +spring-cloud-starter-contract-stub-runner to your classpath and add @AutoConfigureWireMock in +order to be able to use Wiremock in your tests. Wiremock runs as a stub server and you +can register stub behavior using a Java API or via static JSON declarations as part of +your test. The following code shows an example:

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@AutoConfigureWireMock(port = 0)
+public class WiremockForDocsTests {
+	// A service that calls out over HTTP
+	@Autowired private Service service;
+
+	// Using the WireMock APIs in the normal way:
+	@Test
+	public void contextLoads() throws Exception {
+		// Stubbing WireMock
+		stubFor(get(urlEqualTo("/resource"))
+				.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
+		// We're asserting if WireMock responded properly
+		assertThat(this.service.go()).isEqualTo("Hello World!");
+	}
+
+}

To start the stub server on a different port use (for example), +@AutoConfigureWireMock(port=9999). For a random port, use a value of 0. The stub +server port can be bound in the test application context with the "wiremock.server.port" +property. Using @AutoConfigureWireMock adds a bean of type WiremockConfiguration to +your test application context, where it will be cached in between methods and classes +having the same context, the same as for Spring integration tests.

94.1 Registering Stubs Automatically

If you use @AutoConfigureWireMock, it registers WireMock JSON stubs from the file +system or classpath (by default, from file:src/test/resources/mappings). You can +customize the locations using the stubs attribute in the annotation, which can be an +Ant-style resource pattern or a directory. In the case of a directory, */.json is +appended. The following code shows an example:

@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureWireMock(stubs="classpath:/stubs")
+public class WiremockImportApplicationTests {
+
+	@Autowired
+	private Service service;
+
+	@Test
+	public void contextLoads() throws Exception {
+		assertThat(this.service.go()).isEqualTo("Hello World!");
+	}
+
+}
[Note]Note

Actually, WireMock always loads mappings from src/test/resources/mappings as +well as the custom locations in the stubs attribute. To change this behavior, you can +also specify a files root as described in the next section of this document.

94.2 Using Files to Specify the Stub Bodies

WireMock can read response bodies from files on the classpath or the file system. In that +case, you can see in the JSON DSL that the response has a bodyFileName instead of a +(literal) body. The files are resolved relative to a root directory (by default, +src/test/resources/__files). To customize this location you can set the files +attribute in the @AutoConfigureWireMock annotation to the location of the parent +directory (in other words, __files is a subdirectory). You can use Spring resource +notation to refer to file:…​ or classpath:…​ locations. Generic URLs are not +supported. A list of values can be given, in which case WireMock resolves the first file +that exists when it needs to find a response body.

[Note]Note

When you configure the files root, it also affects the +automatic loading of stubs, because they come from the root location +in a subdirectory called "mappings". The value of files has no +effect on the stubs loaded explicitly from the stubs attribute.

94.3 Alternative: Using JUnit Rules

For a more conventional WireMock experience, you can use JUnit @Rules to start and stop +the server. To do so, use the WireMockSpring convenience class to obtain an Options +instance, as shown in the following example:

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+public class WiremockForDocsClassRuleTests {
+
+	// Start WireMock on some dynamic port
+	// for some reason `dynamicPort()` is not working properly
+	@ClassRule
+	public static WireMockClassRule wiremock = new WireMockClassRule(
+			WireMockSpring.options().dynamicPort());
+	// A service that calls out over HTTP to localhost:${wiremock.port}
+	@Autowired
+	private Service service;
+
+	// Using the WireMock APIs in the normal way:
+	@Test
+	public void contextLoads() throws Exception {
+		// Stubbing WireMock
+		wiremock.stubFor(get(urlEqualTo("/resource"))
+				.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
+		// We're asserting if WireMock responded properly
+		assertThat(this.service.go()).isEqualTo("Hello World!");
+	}
+
+}

The @ClassRule means that the server shuts down after all the methods in this class +have been run.

94.4 Relaxed SSL Validation for Rest Template

WireMock lets you stub a "secure" server with an "https" URL protocol. If your +application wants to contact that stub server in an integration test, it will find that +the SSL certificates are not valid (the usual problem with self-installed certificates). +The best option is often to re-configure the client to use "http". If that’s not an +option, you can ask Spring to configure an HTTP client that ignores SSL validation errors +(do so only for tests, of course).

To make this work with minimum fuss, you need to be using the Spring Boot +RestTemplateBuilder in your app, as shown in the following example:

@Bean
+public RestTemplate restTemplate(RestTemplateBuilder builder) {
+	return builder.build();
+}

You need RestTemplateBuilder because the builder is passed through callbacks to +initialize it, so the SSL validation can be set up in the client at that point. This +happens automatically in your test if you are using the @AutoConfigureWireMock +annotation or the stub runner. If you use the JUnit @Rule approach, you need to add the +@AutoConfigureHttpClient annotation as well, as shown in the following example:

@RunWith(SpringRunner.class)
+@SpringBootTest("app.baseUrl=https://localhost:6443")
+@AutoConfigureHttpClient
+public class WiremockHttpsServerApplicationTests {
+
+	@ClassRule
+	public static WireMockClassRule wiremock = new WireMockClassRule(
+			WireMockSpring.options().httpsPort(6443));
+...
+}

If you are using spring-boot-starter-test, you have the Apache HTTP client on the +classpath and it is selected by the RestTemplateBuilder and configured to ignore SSL +errors. If you use the default java.net client, you do not need the annotation (but it +won’t do any harm). There is no support currently for other clients, but it may be added +in future releases.

94.5 WireMock and Spring MVC Mocks

Spring Cloud Contract provides a convenience class that can load JSON WireMock stubs into +a Spring MockRestServiceServer. The following code shows an example:

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.NONE)
+public class WiremockForDocsMockServerApplicationTests {
+
+	@Autowired
+	private RestTemplate restTemplate;
+
+	@Autowired
+	private Service service;
+
+	@Test
+	public void contextLoads() throws Exception {
+		// will read stubs classpath
+		MockRestServiceServer server = WireMockRestServiceServer.with(this.restTemplate)
+				.baseUrl("https://example.org").stubs("classpath:/stubs/resource.json")
+				.build();
+		// We're asserting if WireMock responded properly
+		assertThat(this.service.go()).isEqualTo("Hello World");
+		server.verify();
+	}
+}

The baseUrl value is prepended to all mock calls, and the stubs() method takes a stub +path resource pattern as an argument. In the preceding example, the stub defined at +/stubs/resource.json is loaded into the mock server. If the RestTemplate is asked to +visit https://example.org/, it gets the responses as being declared at that URL. More +than one stub pattern can be specified, and each one can be a directory (for a recursive +list of all ".json"), a fixed filename (as in the example above), or an Ant-style +pattern. The JSON format is the normal WireMock format, which you can read about in the +WireMock website.

Currently, the Spring Cloud Contract Verifier supports Tomcat, Jetty, and Undertow as +Spring Boot embedded servers, and Wiremock itself has "native" support for a particular +version of Jetty (currently 9.2). To use the native Jetty, you need to add the native +Wiremock dependencies and exclude the Spring Boot container (if there is one).

94.6 Customization of WireMock configuration

You can register a bean of org.springframework.cloud.contract.wiremock.WireMockConfigurationCustomizer type +in order to customize the WireMock configuration (e.g. add custom transformers). +Example:

		@Bean WireMockConfigurationCustomizer optionsCustomizer() {
+			return new WireMockConfigurationCustomizer() {
+				@Override public void customize(WireMockConfiguration options) {
+// perform your customization here
+				}
+			};
+		}

94.7 Generating Stubs using REST Docs

Spring REST Docs can be used to generate +documentation (for example in Asciidoctor format) for an HTTP API with Spring MockMvc or +Rest Assured. At the same time that you generate documentation for your API, you can also +generate WireMock stubs by using Spring Cloud Contract WireMock. To do so, write your +normal REST Docs test cases and use @AutoConfigureRestDocs to have stubs be +automatically generated in the REST Docs output directory. The following code shows an +example:

@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureRestDocs(outputDir = "target/snippets")
+@AutoConfigureMockMvc
+public class ApplicationTests {
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@Test
+	public void contextLoads() throws Exception {
+		mockMvc.perform(get("/resource"))
+				.andExpect(content().string("Hello World"))
+				.andDo(document("resource"));
+	}
+}

This test generates a WireMock stub at "target/snippets/stubs/resource.json". It matches +all GET requests to the "/resource" path.

Without any additional configuration, this tests creates a stub with a request matcher +for the HTTP method and all headers except "host" and "content-length". To match the +request more precisely (for example, to match the body of a POST or PUT), we need to +explicitly create a request matcher. Doing so has two effects:

  • Creating a stub that matches only in the way you specify.
  • Asserting that the request in the test case also matches the same conditions.

The main entry point for this feature is WireMockRestDocs.verify(), which can be used +as a substitute for the document() convenience method, as shown in the following +example:

@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureRestDocs(outputDir = "target/snippets")
+@AutoConfigureMockMvc
+public class ApplicationTests {
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@Test
+	public void contextLoads() throws Exception {
+		mockMvc.perform(post("/resource")
+                .content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
+				.andExpect(status().isOk())
+				.andDo(verify().jsonPath("$.id")
+                        .stub("resource"));
+	}
+}

This contract specifies that any valid POST with an "id" field receives the response +defined in this test. You can chain together calls to .jsonPath() to add additional +matchers. If JSON Path is unfamiliar, The JayWay +documentation can help you get up to speed.

Instead of the jsonPath and contentType convenience methods, you can also use the +WireMock APIs to verify that the request matches the created stub, as shown in the +following example:

@Test
+public void contextLoads() throws Exception {
+	mockMvc.perform(post("/resource")
+               .content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
+			.andExpect(status().isOk())
+			.andDo(verify()
+					.wiremock(WireMock.post(
+						urlPathEquals("/resource"))
+						.withRequestBody(matchingJsonPath("$.id"))
+                       .stub("post-resource"));
+}

The WireMock API is rich. You can match headers, query parameters, and request body by +regex as well as by JSON path. These features can be used to create stubs with a wider +range of parameters. The above example generates a stub resembling the following example:

post-resource.json.  +

{
+  "request" : {
+    "url" : "/resource",
+    "method" : "POST",
+    "bodyPatterns" : [ {
+      "matchesJsonPath" : "$.id"
+    }]
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "Hello World",
+    "headers" : {
+      "X-Application-Context" : "application:-1",
+      "Content-Type" : "text/plain"
+    }
+  }
+}

+

[Note]Note

You can use either the wiremock() method or the jsonPath() and contentType() +methods to create request matchers, but you can’t use both approaches.

On the consumer side, you can make the resource.json generated earlier in this section +available on the classpath (by +publishing +stubs as JARs, for example). After that, you can create a stub using WireMock in a +number of different ways, including by using +@AutoConfigureWireMock(stubs="classpath:resource.json"), as described earlier in this +document.

94.8 Generating Contracts by Using REST Docs

You can also generate Spring Cloud Contract DSL files and documentation with Spring REST +Docs. If you do so in combination with Spring Cloud WireMock, you get both the contracts +and the stubs.

Why would you want to use this feature? Some people in the community asked questions +about a situation in which they would like to move to DSL-based contract definition, +but they already have a lot of Spring MVC tests. Using this feature lets you generate +the contract files that you can later modify and move to folders (defined in your +configuration) so that the plugin finds them.

[Tip]Tip

You might wonder why this functionality is in the WireMock module. The functionality +is there because it makes sense to generate both the contracts and the stubs.

Consider the following test:

		this.mockMvc.perform(post("/foo")
+					.accept(MediaType.APPLICATION_PDF)
+					.accept(MediaType.APPLICATION_JSON)
+					.contentType(MediaType.APPLICATION_JSON)
+					.content("{\"foo\": 23, \"bar\" : \"baz\" }"))
+				.andExpect(status().isOk())
+				.andExpect(content().string("bar"))
+				// first WireMock
+				.andDo(WireMockRestDocs.verify()
+						.jsonPath("$[?(@.foo >= 20)]")
+						.jsonPath("$[?(@.bar in ['baz','bazz','bazzz'])]")
+						.contentType(MediaType.valueOf("application/json"))
+						.stub("shouldGrantABeerIfOldEnough"))
+				// then Contract DSL documentation
+				.andDo(document("index", SpringCloudContractRestDocs.dslContract()));

The preceding test creates the stub presented in the previous section, generating both +the contract and a documentation file.

The contract is called index.groovy and might look like the following example:

import org.springframework.cloud.contract.spec.Contract
+
+Contract.make {
+    request {
+        method 'POST'
+        url '/foo'
+        body('''
+            {"foo": 23 }
+        ''')
+        headers {
+            header('''Accept''', '''application/json''')
+            header('''Content-Type''', '''application/json''')
+        }
+    }
+    response {
+        status 200
+        body('''
+        bar
+        ''')
+        headers {
+            header('''Content-Type''', '''application/json;charset=UTF-8''')
+            header('''Content-Length''', '''3''')
+        }
+        testMatchers {
+            jsonPath('$[?(@.foo >= 20)]', byType())
+        }
+    }
+}

The generated document (formatted in Asciidoc in this case) contains a formatted +contract. The location of this file would be index/dsl-contract.adoc.

Prev Up Next
93. Using the Pluggable Architecture Home 95. Migrations
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Part XII. Spring Cloud for Cloud Foundry
Prev   Next

Part XII. Spring Cloud for Cloud Foundry

Spring Cloud for Cloudfoundry makes it easy to run +Spring Cloud apps in +Cloud Foundry (the Platform as a +Service). Cloud Foundry has the notion of a "service", which is +middlware that you "bind" to an app, essentially providing it with an +environment variable containing credentials (e.g. the location and +username to use for the service).

The spring-cloud-cloudfoundry-web project provides basic support for +some enhanced features of webapps in Cloud Foundry: binding +automatically to single-sign-on services and optionally enabling +sticky routing for discovery.

The spring-cloud-cloudfoundry-discovery project provides an +implementation of Spring Cloud Commons DiscoveryClient so you can +@EnableDiscoveryClient and provide your credentials as +spring.cloud.cloudfoundry.discovery.[email,password] and then you +can use the DiscoveryClient directly or via a LoadBalancerClient +(also *.url if you are not connecting to +Pivotal Web Services).

The first time you use it the discovery client might be slow owing to +the fact that it has to get an access token from Cloud Foundry.

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81. Configuring Authentication Downstream of a Zuul Proxy Home 82. Discovery
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Part XV. Spring Cloud Function
Prev   Next

Part XV. Spring Cloud Function

Mark Fisher, Dave Syer

Prev   Next
106. Lease lifecycle management (renewal and revocation) Home 107. Introduction
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Part III. Spring Cloud Netflix
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Part III. Spring Cloud Netflix

1.3.8.RELEASE

This project provides Netflix OSS integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with battle-tested Netflix components. The +patterns provided include Service Discovery (Eureka), Circuit Breaker (Hystrix), +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon).

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10. Spring Cloud Config Client Home 11. Service Discovery: Eureka Clients
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Part XI. Spring Cloud Security
Prev   Next

Part XI. Spring Cloud Security

Spring Cloud Security offers a set of primitives for building secure +applications and services with minimum fuss. A declarative model which +can be heavily configured externally (or centrally) lends itself to +the implementation of large systems of co-operating, remote components, +usually with a central indentity management service. It is also extremely +easy to use in a service platform like Cloud Foundry. Building on +Spring Boot and Spring Security OAuth2 we can quickly create systems that +implement common patterns like single sign on, token relay and token +exchange.

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

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78. Encryption and Decryption Home 79. Quickstart
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Part VII. Spring Cloud Sleuth
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Part VII. Spring Cloud Sleuth

Adrian Cole, Spencer Gibb, Marcin Grzejszczak, Dave Syer

1.3.8.RELEASE

Prev   Next
45. Broadcasting Your Own Events Home 46. Introduction
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Part IV. Spring Cloud Stream
Prev   Next

Part IV. Spring Cloud Stream

This section goes into more detail about how you can work with Spring Cloud Stream. +It covers topics such as creating and running stream applications.

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23. HTTP Clients Home 24. Introducing Spring Cloud Stream
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Part XIV. Spring Cloud Vault
Prev   Next

Part XIV. Spring Cloud Vault

© 2016-2017 The original authors.

[Note]Note

Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.

Spring Cloud Vault Config provides client-side support for externalized configuration in a distributed system. With HashiCorp’s Vault you have a central place to manage external secret properties for applications across all environments. Vault can manage static and dynamic secrets such as username/password for remote applications/resources and provide credentials for external services such as MySQL, PostgreSQL, Apache Cassandra, MongoDB, Consul, AWS and more.

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96. Links Home 97. Quick Start
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Part IX. Spring Cloud Zookeeper
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Part IX. Spring Cloud Zookeeper

This project provides Zookeeper integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with Zookeeper based components. The +patterns provided include Service Discovery and Configuration. +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker +(Hystrix) are provided by integration with Spring Cloud Netflix.

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67. Hystrix metrics aggregation with Turbine and Consul Home 68. Install Zookeeper
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112. Standalone Streaming Applications
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112. Standalone Streaming Applications

To send or receive messages from a broker (such as RabbitMQ or Kafka) you can use the spring-cloud-function-stream adapter. Add the adapter to your classpath along with the appropriate binder from Spring Cloud Stream. The adapter will bind to the message broker as a Processor (input and output streams) unless the user explicitly disables one or the other using spring.cloud.function.stream.{source,sink}.enabled=false.

An incoming message is routed to a function (or consumer). If there is only one, then the choice is obvious. If there are multiple functions that can accept an incoming message, the message is inspected to see if there is a stream_routekey header containing the name of a function. Routing headers or function names can be composed using a comma- or pipe-separated name. The header is also added to outgoing messages from a supplier. Messages with no route key can be routed exclusively to a function or consumer by specifying spring.cloud.function.stream.{processor,sink}.name. If a single function cannot be identified to process an incoming message there will be an error, unless you set spring.cloud.function.stream.shared=true, in which case such messages will be sent to all compatible functions. A single supplier can be chosen for output messages from a supplier (if more than one is available) using the spring.cloud.function.stream.source.name.

[Note]Note

some binders will fail on startup if the message broker is not available and the function catalog contains suppliers that immediately produce messages when accessed. You can switch off the automatic publishing from suppliers on startup using the spring.cloud.function.strean.supplier.enabled=false flag.

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111. Standalone Web Applications Home 113. Deploying a Packaged Function
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111. Standalone Web Applications
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111. Standalone Web Applications

The spring-cloud-function-web module has autoconfiguration that +activates when it is included in a Spring Boot web application (with +MVC support). There is also a spring-cloud-starter-function-web to +collect all the optional dependnecies in case you just want a simple +getting started experience.

With the web configurations activated your app will have an MVC +endpoint (on "/" by default, but configurable with +spring.cloud.function.web.path) that can be used to access the +functions in the application context. The supported content types are +plain text and JSON.

MethodPathRequestResponseStatus

GET

/{supplier}

-

Items from the named supplier

200 OK

POST

/{consumer}

JSON object or text

Mirrors input and pushes request body into consumer

202 Accepted

POST

/{consumer}

JSON array or text with new lines

Mirrors input and pushes body into consumer one by one

202 Accepted

POST

/{function}

JSON object or text

The result of applying the named function

200 OK

POST

/{function}

JSON array or text with new lines

The result of applying the named function

200 OK

GET

/{function}/{item}

-

Convert the item into an object and return the result of applying the function

200 OK

As the table above shows the behaviour of the endpoint depends on the method and also the type of incoming request data. When the incoming data is single valued, and the target function is declared as obviously single valued (i.e. not returning a collection or Flux), then the response will also contain a single value. For multi-valued responses the client can ask for a server-sent event stream by sending `Accept: text/event-stream". If there is only one function (consumer etc.) then the name in the path is optional. Composite functions can be addressed using pipes or commas to separate function names (pipes are legal in URL paths, but a bit awkward to type on the command line).

Functions and consumers that are declared with input and output in Message<?> will see the request headers on the input messages, and the output message headers will be converted to HTTP headers.

When POSTing text the response format might be different with Spring Boot 2.0 and older versions, depending on the content negotiation (provide content type and accpt headers for the best results).

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110. Function Catalog and Flexible Function Signatures Home 112. Standalone Streaming Applications
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90. Stub Runner for Messaging
Prev Part XIII. Spring Cloud Contract Next

90. Stub Runner for Messaging

Stub Runner can run the published stubs in memory. It can integrate with the following +frameworks:

  • Spring Integration
  • Spring Cloud Stream
  • Apache Camel
  • Spring AMQP

It also provides entry points to integrate with any other solution on the market.

[Important]Important

If you have multiple frameworks on the classpath Stub Runner will need to +define which one should be used. Let’s assume that you have both AMQP, Spring Cloud Stream and Spring Integration +on the classpath. Then you need to set stubrunner.stream.enabled=false and stubrunner.integration.enabled=false. +That way the only remaining framework is Spring AMQP.

90.1 Stub triggering

To trigger a message, use the StubTrigger interface:

package org.springframework.cloud.contract.stubrunner;
+
+import java.util.Collection;
+import java.util.Map;
+
+public interface StubTrigger {
+
+	/**
+	 * Triggers an event by a given label for a given {@code groupid:artifactid} notation. You can use only {@code artifactId} too.
+	 *
+	 * Feature related to messaging.
+	 *
+	 * @return true - if managed to run a trigger
+	 */
+	boolean trigger(String ivyNotation, String labelName);
+
+	/**
+	 * Triggers an event by a given label.
+	 *
+	 * Feature related to messaging.
+	 *
+	 * @return true - if managed to run a trigger
+	 */
+	boolean trigger(String labelName);
+
+	/**
+	 * Triggers all possible events.
+	 *
+	 * Feature related to messaging.
+	 *
+	 * @return true - if managed to run a trigger
+	 */
+	boolean trigger();
+
+	/**
+	 * Returns a mapping of ivy notation of a dependency to all the labels it has.
+	 *
+	 * Feature related to messaging.
+	 */
+	Map<String, Collection<String>> labels();
+}

For convenience, the StubFinder interface extends StubTrigger, so you only need one +or the other in your tests.

StubTrigger gives you the following options to trigger a message:

90.1.1 Trigger by Label

stubFinder.trigger('return_book_1')

90.1.2 Trigger by Group and Artifact Ids

stubFinder.trigger('org.springframework.cloud.contract.verifier.stubs:camelService', 'return_book_1')

90.1.3 Trigger by Artifact Ids

stubFinder.trigger('camelService', 'return_book_1')

90.1.4 Trigger All Messages

stubFinder.trigger()

90.2 Stub Runner Camel

Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Apache Camel. For the provided artifacts, it automatically downloads the +stubs and registers the required routes.

90.2.1 Adding the Runner to the Project

You can have both Apache Camel and Spring Cloud Contract Stub Runner on the classpath. +Remember to annotate your test class with @AutoConfigureStubRunner.

90.2.2 Disabling the functionality

If you need to disable this functionality, set the stubrunner.camel.enabled=false +property.

Assume that you have the following Maven repository with deployed stubs for the +camelService application:

└── .m2
+    └── repository
+        └── io
+            └── codearte
+                └── accurest
+                    └── stubs
+                        └── camelService
+                            ├── 0.0.1-SNAPSHOT
+                            │   ├── camelService-0.0.1-SNAPSHOT.pom
+                            │   ├── camelService-0.0.1-SNAPSHOT-stubs.jar
+                            │   └── maven-metadata-local.xml
+                            └── maven-metadata-local.xml

Further assume that the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── repository
+    ├── accurest
+    │   ├── bookDeleted.groovy
+    │   ├── bookReturned1.groovy
+    │   └── bookReturned2.groovy
+    └── mappings

Consider the following contracts (numbered 1):

Contract.make {
+	label 'return_book_1'
+	input {
+		triggeredBy('bookReturnedTriggered()')
+	}
+	outputMessage {
+		sentTo('jms:output')
+		body('''{ "bookName" : "foo" }''')
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

Now consider 2

Contract.make {
+	label 'return_book_2'
+	input {
+		messageFrom('jms:input')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('jms:output')
+		body([
+				bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

These examples lend themselves to three scenarios:

Scenario 1 (no input message)

To trigger a message via the return_book_1 label, use the StubTigger interface, as +follows:

stubFinder.trigger('return_book_1')

To listen to the output of the message sent to jms:output:

Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000)

The received message passes the following assertions:

receivedMessage != null
+assertThatBodyContainsBookNameFoo(receivedMessage.in.body)
+receivedMessage.in.headers.get('BOOK-NAME') == 'foo'

Scenario 2 (output triggered by input)

Since the route is set for you, you can send a message to the jms:output +destination:

camelContext.createProducerTemplate().sendBodyAndHeaders('jms:input', new BookReturned('foo'), [sample: 'header'])

You can listen to the output of the message sent to jms:output:

Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000)

The received message passes the following assertions:

receivedMessage != null
+assertThatBodyContainsBookNameFoo(receivedMessage.in.body)
+receivedMessage.in.headers.get('BOOK-NAME') == 'foo'

Scenario 3 (input with no output)

Since the route is set for you, you can send a message to the jms:output +destination:

camelContext.createProducerTemplate().sendBodyAndHeaders('jms:delete', new BookReturned('foo'), [sample: 'header'])

90.3 Stub Runner Integration

Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Spring Integration. For the provided artifacts, it automatically downloads +the stubs and registers the required routes.

90.3.1 Adding the Runner to the Project

You can have both Spring Integration and Spring Cloud Contract Stub Runner on the +classpath. Remember to annotate your test class with @AutoConfigureStubRunner.

90.3.2 Disabling the functionality

If you need to disable this functionality, set the +stubrunner.integration.enabled=false property.

Assume that you have the following Maven repository with deployed stubs for the +integrationService application:

└── .m2
+    └── repository
+        └── io
+            └── codearte
+                └── accurest
+                    └── stubs
+                        └── integrationService
+                            ├── 0.0.1-SNAPSHOT
+                            │   ├── integrationService-0.0.1-SNAPSHOT.pom
+                            │   ├── integrationService-0.0.1-SNAPSHOT-stubs.jar
+                            │   └── maven-metadata-local.xml
+                            └── maven-metadata-local.xml

Further assume the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── repository
+    ├── accurest
+    │   ├── bookDeleted.groovy
+    │   ├── bookReturned1.groovy
+    │   └── bookReturned2.groovy
+    └── mappings

Consider the following contracts (numbered 1):

Contract.make {
+	label 'return_book_1'
+	input {
+		triggeredBy('bookReturnedTriggered()')
+	}
+	outputMessage {
+		sentTo('output')
+		body('''{ "bookName" : "foo" }''')
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

Now consider 2:

Contract.make {
+	label 'return_book_2'
+	input {
+		messageFrom('input')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('output')
+		body([
+				bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

and the following Spring Integration Route:

<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/integration"
+			 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+			 xmlns:beans="http://www.springframework.org/schema/beans"
+			 xsi:schemaLocation="http://www.springframework.org/schema/beans
+			https://www.springframework.org/schema/beans/spring-beans.xsd
+			http://www.springframework.org/schema/integration
+			https://www.springframework.org/schema/integration/spring-integration.xsd">
+
+
+	<!-- REQUIRED FOR TESTING -->
+	<bridge input-channel="output"
+			output-channel="outputTest"/>
+
+	<channel id="outputTest">
+		<queue/>
+	</channel>
+
+</beans:beans>

These examples lend themselves to three scenarios:

Scenario 1 (no input message)

To trigger a message via the return_book_1 label, use the StubTigger interface, as +follows:

stubFinder.trigger('return_book_1')

To listen to the output of the message sent to output:

Message<?> receivedMessage = messaging.receive('outputTest')

The received message would pass the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 2 (output triggered by input)

Since the route is set for you, you can send a message to the output +destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'input')

To listen to the output of the message sent to output:

Message<?> receivedMessage = messaging.receive('outputTest')

The received message passes the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 3 (input with no output)

Since the route is set for you, you can send a message to the input destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete')

90.4 Stub Runner Stream

Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Spring Stream. For the provided artifacts, it automatically downloads the +stubs and registers the required routes.

[Warning]Warning

If Stub Runner’s integration with Stream the messageFrom or sentTo Strings +are resolved first as a destination of a channel and no such destination exists, the +destination is resolved as a channel name.

[Important]Important

If you want to use Spring Cloud Stream remember, to add a dependency on +org.springframework.cloud:spring-cloud-stream-test-support.

Maven.  +

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-stream-test-support</artifactId>
+    <scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile "org.springframework.cloud:spring-cloud-stream-test-support"

+

90.4.1 Adding the Runner to the Project

You can have both Spring Cloud Stream and Spring Cloud Contract Stub Runner on the +classpath. Remember to annotate your test class with @AutoConfigureStubRunner.

90.4.2 Disabling the functionality

If you need to disable this functionality, set the stubrunner.stream.enabled=false +property.

Assume that you have the following Maven repository with a deployed stubs for the +streamService application:

└── .m2
+    └── repository
+        └── io
+            └── codearte
+                └── accurest
+                    └── stubs
+                        └── streamService
+                            ├── 0.0.1-SNAPSHOT
+                            │   ├── streamService-0.0.1-SNAPSHOT.pom
+                            │   ├── streamService-0.0.1-SNAPSHOT-stubs.jar
+                            │   └── maven-metadata-local.xml
+                            └── maven-metadata-local.xml

Further assume the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── repository
+    ├── accurest
+    │   ├── bookDeleted.groovy
+    │   ├── bookReturned1.groovy
+    │   └── bookReturned2.groovy
+    └── mappings

Consider the following contracts (numbered 1):

Contract.make {
+	label 'return_book_1'
+	input { triggeredBy('bookReturnedTriggered()') }
+	outputMessage {
+		sentTo('returnBook')
+		body('''{ "bookName" : "foo" }''')
+		headers { header('BOOK-NAME', 'foo') }
+	}
+}

Now consider 2:

Contract.make {
+	label 'return_book_2'
+	input {
+		messageFrom('bookStorage')
+		messageBody([
+			bookName: 'foo'
+		])
+		messageHeaders { header('sample', 'header') }
+	}
+	outputMessage {
+		sentTo('returnBook')
+		body([
+			bookName: 'foo'
+		])
+		headers { header('BOOK-NAME', 'foo') }
+	}
+}

Now consider the following Spring configuration:

stubrunner.repositoryRoot: classpath:m2repo/repository/
+stubrunner.ids: org.springframework.cloud.contract.verifier.stubs:streamService:0.0.1-SNAPSHOT:stubs
+
+spring:
+  cloud:
+    stream:
+      bindings:
+        output:
+          destination: returnBook
+        input:
+          destination: bookStorage
+
+server:
+  port: 0
+
+debug: true

These examples lend themselves to three scenarios:

Scenario 1 (no input message)

To trigger a message via the return_book_1 label, use the StubTrigger interface as +follows:

stubFinder.trigger('return_book_1')

To listen to the output of the message sent to a channel whose destination is +returnBook:

Message<?> receivedMessage = messaging.receive('returnBook')

The received message passes the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 2 (output triggered by input)

Since the route is set for you, you can send a message to the bookStorage +destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'bookStorage')

To listen to the output of the message sent to returnBook:

Message<?> receivedMessage = messaging.receive('returnBook')

The received message passes the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 3 (input with no output)

Since the route is set for you, you can send a message to the output +destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete')

90.5 Stub Runner Spring AMQP

Spring Cloud Contract Verifier Stub Runner’s messaging module provides an easy way to +integrate with Spring AMQP’s Rabbit Template. For the provided artifacts, it +automatically downloads the stubs and registers the required routes.

The integration tries to work standalone (that is, without interaction with a running +RabbitMQ message broker). It expects a RabbitTemplate on the application context and +uses it as a spring boot test named @SpyBean. As a result, it can use the mockito spy +functionality to verify and inspect messages sent by the application.

On the message consumer side, the stub runner considers all @RabbitListener annotated +endpoints and all SimpleMessageListenerContainer objects on the application context.

As messages are usually sent to exchanges in AMQP, the message contract contains the +exchange name as the destination. Message listeners on the other side are bound to +queues. Bindings connect an exchange to a queue. If message contracts are triggered, the +Spring AMQP stub runner integration looks for bindings on the application context that +match this exchange. Then it collects the queues from the Spring exchanges and tries to +find message listeners bound to these queues. The message is triggered for all matching +message listeners.

90.5.1 Adding the Runner to the Project

You can have both Spring AMQP and Spring Cloud Contract Stub Runner on the classpath and +set the property stubrunner.amqp.enabled=true. Remember to annotate your test class +with @AutoConfigureStubRunner.

[Important]Important

If you already have Stream and Integration on the classpath, you need +to disable them explicitly by setting the stubrunner.stream.enabled=false and +stubrunner.integration.enabled=false properties.

Assume that you have the following Maven repository with a deployed stubs for the +spring-cloud-contract-amqp-test application.

└── .m2
+    └── repository
+        └── com
+            └── example
+                └── spring-cloud-contract-amqp-test
+                    ├── 0.4.0-SNAPSHOT
+                    │   ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT.pom
+                    │   ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT-stubs.jar
+                    │   └── maven-metadata-local.xml
+                    └── maven-metadata-local.xml

Further assume that the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── contracts
+    └── shouldProduceValidPersonData.groovy

Consider the following contract:

Contract.make {
+    // Human readable description
+    description 'Should produce valid person data'
+    // Label by means of which the output message can be triggered
+    label 'contract-test.person.created.event'
+    // input to the contract
+    input {
+        // the contract will be triggered by a method
+        triggeredBy('createPerson()')
+    }
+    // output message of the contract
+    outputMessage {
+        // destination to which the output message will be sent
+        sentTo 'contract-test.exchange'
+        headers {
+            header('contentType': 'application/json')
+            header('__TypeId__': 'org.springframework.cloud.contract.stubrunner.messaging.amqp.Person')
+        }
+        // the body of the output message
+        body ([
+                id: $(consumer(9), producer(regex("[0-9]+"))),
+                name: "me"
+        ])
+    }
+}

Now consider the following Spring configuration:

stubrunner:
+  repositoryRoot: classpath:m2repo/repository/
+  ids: org.springframework.cloud.contract.verifier.stubs.amqp:spring-cloud-contract-amqp-test:0.4.0-SNAPSHOT:stubs
+  amqp:
+    enabled: true
+server:
+  port: 0

Triggering the message

To trigger a message using the contract above, use the StubTrigger interface as +follows:

stubTrigger.trigger("contract-test.person.created.event")

The message has a destination of contract-test.exchange, so the Spring AMQP stub runner +integration looks for bindings related to this exchange.

@Bean
+public Binding binding() {
+	return BindingBuilder.bind(new Queue("test.queue")).to(new DirectExchange("contract-test.exchange")).with("#");
+}

The binding definition binds the queue test.queue. As a result, the following listener +definition is matched and invoked with the contract message.

@Bean
+public SimpleMessageListenerContainer simpleMessageListenerContainer(ConnectionFactory connectionFactory,
+																		MessageListenerAdapter listenerAdapter) {
+	SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
+	container.setConnectionFactory(connectionFactory);
+	container.setQueueNames("test.queue");
+	container.setMessageListener(listenerAdapter);
+
+	return container;
+}

Also, the following annotated listener matches and is invoked:

@RabbitListener(bindings = @QueueBinding(
+		value = @Queue(value = "test.queue"),
+		exchange = @Exchange(value = "contract-test.exchange", ignoreDeclarationExceptions = "true")))
+public void handlePerson(Person person) {
+	this.person = person;
+}
[Note]Note

The message is directly handed over to the onMessage method of the +MessageListener associated with the matching SimpleMessageListenerContainer.

Spring AMQP Test Configuration

In order to avoid Spring AMQP trying to connect to a running broker during our tests +configure a mock ConnectionFactory.

To disable the mocked ConnectionFactory, set the following property: +stubrunner.amqp.mockConnection=false

stubrunner:
+  amqp:
+    mockConnection: false
Prev Up Next
89. Spring Cloud Contract Stub Runner Home 91. Contract DSL
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32. Testing
Prev Part IV. Spring Cloud Stream Next

32. Testing

Spring Cloud Stream provides support for testing your microservice applications without connecting to a messaging system. +You can do that by using the TestSupportBinder provided by the spring-cloud-stream-test-support library, which can be added as a test dependency to the application:

   <dependency>
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-stream-test-support</artifactId>
+       <scope>test</scope>
+   </dependency>
[Note]Note

The TestSupportBinder uses the Spring Boot autoconfiguration mechanism to supersede the other binders found on the classpath. +Therefore, when adding a binder as a dependency, make sure that the test scope is being used.

The TestSupportBinder allows users to interact with the bound channels and inspect what messages are sent and received by the application

For outbound message channels, the TestSupportBinder registers a single subscriber and retains the messages emitted by the application in a MessageCollector. +They can be retrieved during tests and have assertions made against them.

The user can also send messages to inbound message channels, so that the consumer application can consume the messages. +The following example shows how to test both input and output channels on a processor.

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment= SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class ExampleTest {
+
+  @Autowired
+  private Processor processor;
+
+  @Autowired
+  private MessageCollector messageCollector;
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void testWiring() {
+    Message<String> message = new GenericMessage<>("hello");
+    processor.input().send(message);
+    Message<String> received = (Message<String>) messageCollector.forChannel(processor.output()).poll();
+    assertThat(received.getPayload(), equalTo("hello world"));
+  }
+
+
+  @SpringBootApplication
+  @EnableBinding(Processor.class)
+  public static class MyProcessor {
+
+    @Autowired
+    private Processor channels;
+
+    @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
+    public String transform(String in) {
+      return in + " world";
+    }
+  }
+}

In the example above, we are creating an application that has an input and an output channel, bound through the Processor interface. +The bound interface is injected into the test so we can have access to both channels. +We are sending a message on the input channel and we are using the MessageCollector provided by Spring Cloud Stream’s test support to capture the message has been sent to the output channel as a result. +Once we have received the message, we can validate that the component functions correctly.

32.1 Disabling the test binder autoconfiguration

The intent behind the test binder superseding all the other binders on the classpath is to make it easy to test your applications without making changes to your production dependencies. +In some cases (e.g. integration tests) it is useful to use the actual production binders instead, and that requires disabling the test binder autoconfiguration. +In order to do so, you can exclude the org.springframework.cloud.stream.test.binder.TestSupportBinderAutoConfiguration class using one of the Spring Boot autoconfiguration exclusion mechanisms, as in the following example.

	@SpringBootApplication(exclude = TestSupportBinderAutoConfiguration.class)
+	@EnableBinding(Processor.class)
+	public static class MyProcessor {
+
+		@Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
+		public String transform(String in) {
+			return in + " world";
+		}
+	}

When autoconfiguration is disabled, the test binder is available on the classpath, and its defaultCandidate property is set to false, so that it does not interfere with the regular user configuration. It can be referenced under the name test e.g.:

spring.cloud.stream.defaultBinder=test
Prev Up Next
31. Inter-Application Communication Home 33. Health Indicator
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44. Tracing Bus Events
Prev Part VI. Spring Cloud Bus Next

44. Tracing Bus Events

Bus events (subclasses of RemoteApplicationEvent) can be traced by +setting spring.cloud.bus.trace.enabled=true. If you do this then the +Spring Boot TraceRepository (if it is present) will show each event +sent and all the acks from each service instance. Example (from the +/trace endpoint):

{
+  "timestamp": "2015-11-26T10:24:44.411+0000",
+  "info": {
+    "signal": "spring.cloud.bus.ack",
+    "type": "RefreshRemoteApplicationEvent",
+    "id": "c4d374b7-58ea-4928-a312-31984def293b",
+    "origin": "stores:8081",
+    "destination": "*:**"
+  }
+  },
+  {
+  "timestamp": "2015-11-26T10:24:41.864+0000",
+  "info": {
+    "signal": "spring.cloud.bus.sent",
+    "type": "RefreshRemoteApplicationEvent",
+    "id": "c4d374b7-58ea-4928-a312-31984def293b",
+    "origin": "customers:9000",
+    "destination": "*:**"
+  }
+  },
+  {
+  "timestamp": "2015-11-26T10:24:41.862+0000",
+  "info": {
+    "signal": "spring.cloud.bus.ack",
+    "type": "RefreshRemoteApplicationEvent",
+    "id": "c4d374b7-58ea-4928-a312-31984def293b",
+    "origin": "customers:9000",
+    "destination": "*:**"
+  }
+}

This trace shows that a RefreshRemoteApplicationEvent was sent from +customers:9000, broadcast to all services, and it was received +(acked) by customers:9000 and stores:8081.

To handle the ack signals yourself you could add an @EventListener +for the AckRemoteApplicationEvent and SentApplicationEvent types +to your app (and enable tracing). Or you could tap into the +TraceRepository and mine the data from there.

[Note]Note

Any Bus application can trace acks, but sometimes it will be +useful to do this in a central service that can do more complex +queries on the data. Or forward it to a specialized tracing service.

Prev Up Next
43. Customizing the Message Broker Home 45. Broadcasting Your Own Events
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93. Using the Pluggable Architecture
Prev Part XIII. Spring Cloud Contract Next

93. Using the Pluggable Architecture

You may encounter cases where you have your contracts have been defined in other formats, +such as YAML, RAML or PACT. In those cases, you still want to benefit from the automatic +generation of tests and stubs. You can add your own implementation for generating both +tests and stubs. Also, you can customize the way tests are generated (for example, you +can generate tests for other languages) and the way stubs are generated (for example, you +can generate stubs for other HTTP server implementations).

93.1 Custom Contract Converter

The ContractConverter interface lets you register your own implementation of a contract +structure converter. The following code listing shows the ContractConverter interface:

package org.springframework.cloud.contract.spec
+
+/**
+ * Converter to be used to convert FROM {@link File} TO {@link Contract}
+ * and from {@link Contract} to {@code T}
+ *
+ * @param <T> - type to which we want to convert the contract
+ *
+ * @author Marcin Grzejszczak
+ * @since 1.1.0
+ */
+interface ContractConverter<T> {
+
+	/**
+	 * Should this file be accepted by the converter. Can use the file extension
+	 * to check if the conversion is possible.
+	 *
+	 * @param file - file to be considered for conversion
+	 * @return - {@code true} if the given implementation can convert the file
+	 */
+	boolean isAccepted(File file)
+
+	/**
+	 * Converts the given {@link File} to its {@link Contract} representation
+	 *
+	 * @param file - file to convert
+	 * @return - {@link Contract} representation of the file
+	 */
+	Collection<Contract> convertFrom(File file)
+
+	/**
+	 * Converts the given {@link Contract} to a {@link T} representation
+	 *
+	 * @param contract - the parsed contract
+	 * @return - {@link T} the type to which we do the conversion
+	 */
+	T convertTo(Collection<Contract> contract)
+}

Your implementation must define the condition on which it should start the +conversion. Also, you must define how to perform that conversion in both directions.

[Important]Important

Once you create your implementation, you must create a +/META-INF/spring.factories file in which you provide the fully qualified name of your +implementation.

The following example shows a typical spring.factories file:

org.springframework.cloud.contract.spec.ContractConverter=\
+org.springframework.cloud.contract.verifier.converter.YamlContractConverter

93.1.1 Pact Converter

Spring Cloud Contract includes support for Pact representation of +contracts. Instead of using the Groovy DSL, you can use Pact files. In this section, we +present how to add Pact support for your project.

93.1.2 Pact Contract

Consider following example of a Pact contract, which is a file under the +src/test/resources/contracts folder.

{
+  "provider": {
+    "name": "Provider"
+  },
+  "consumer": {
+    "name": "Consumer"
+  },
+  "interactions": [
+    {
+      "description": "",
+      "request": {
+        "method": "PUT",
+        "path": "/fraudcheck",
+        "headers": {
+          "Content-Type": "application/vnd.fraud.v1+json"
+        },
+        "body": {
+          "clientId": "1234567890",
+          "loanAmount": 99999
+        },
+        "matchingRules": {
+          "$.body.clientId": {
+            "match": "regex",
+            "regex": "[0-9]{10}"
+          }
+        }
+      },
+      "response": {
+        "status": 200,
+        "headers": {
+          "Content-Type": "application/vnd.fraud.v1+json;charset=UTF-8"
+        },
+        "body": {
+          "fraudCheckStatus": "FRAUD",
+          "rejectionReason": "Amount too high"
+        },
+        "matchingRules": {
+          "$.body.fraudCheckStatus": {
+            "match": "regex",
+            "regex": "FRAUD"
+          }
+        }
+      }
+    }
+  ],
+  "metadata": {
+    "pact-specification": {
+      "version": "2.0.0"
+    },
+    "pact-jvm": {
+      "version": "2.4.18"
+    }
+  }
+}

The remainder of this section about using Pact refers to the preceding file.

93.1.3 Pact for Producers

On the producer side, you mustadd two additional dependencies to your plugin +configuration. One is the Spring Cloud Contract Pact support, and the other represents +the current Pact version that you use.

Maven.  +

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-contract-spec-pact</artifactId>
+			<version>${spring-cloud-contract.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>au.com.dius</groupId>
+			<artifactId>pact-jvm-model</artifactId>
+			<version>2.4.18</version>
+		</dependency>
+	</dependencies>
+</plugin>

+

Gradle.  +

classpath "org.springframework.cloud:spring-cloud-contract-spec-pact:${findProperty('verifierVersion') ?: verifierVersion}"
+classpath 'au.com.dius:pact-jvm-model:2.4.18'

+

When you execute the build of your application, a test will be generated. The generated +test might be as follows:

@Test
+public void validate_shouldMarkClientAsFraud() throws Exception {
+	// given:
+		MockMvcRequestSpecification request = given()
+				.header("Content-Type", "application/vnd.fraud.v1+json")
+				.body("{\"clientId\":\"1234567890\",\"loanAmount\":99999}");
+
+	// when:
+		ResponseOptions response = given().spec(request)
+				.put("/fraudcheck");
+
+	// then:
+		assertThat(response.statusCode()).isEqualTo(200);
+		assertThat(response.header("Content-Type")).isEqualTo("application/vnd.fraud.v1+json;charset=UTF-8");
+	// and:
+		DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+		assertThatJson(parsedJson).field("rejectionReason").isEqualTo("Amount too high");
+	// and:
+		assertThat(parsedJson.read("$.fraudCheckStatus", String.class)).matches("FRAUD");
+}

The corresponding generated stub might be as follows:

{
+  "uuid" : "996ae5ae-6834-4db6-8fac-358ca187ab62",
+  "request" : {
+    "url" : "/fraudcheck",
+    "method" : "PUT",
+    "headers" : {
+      "Content-Type" : {
+        "equalTo" : "application/vnd.fraud.v1+json"
+      }
+    },
+    "bodyPatterns" : [ {
+      "matchesJsonPath" : "$[?(@.loanAmount == 99999)]"
+    }, {
+      "matchesJsonPath" : "$[?(@.clientId =~ /([0-9]{10})/)]"
+    } ]
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "{\"fraudCheckStatus\":\"FRAUD\",\"rejectionReason\":\"Amount too high\"}",
+    "headers" : {
+      "Content-Type" : "application/vnd.fraud.v1+json;charset=UTF-8"
+    }
+  }
+}

93.1.4 Pact for Consumers

On the producer side, you must add two additional dependencies to your project +dependencies. One is the Spring Cloud Contract Pact support, and the other represents the +current Pact version that you use.

Maven.  +

<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-spec-pact</artifactId>
+	<scope>test</scope>
+</dependency>
+<dependency>
+	<groupId>au.com.dius</groupId>
+	<artifactId>pact-jvm-model</artifactId>
+	<version>2.4.18</version>
+	<scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile "org.springframework.cloud:spring-cloud-contract-spec-pact"
+testCompile 'au.com.dius:pact-jvm-model:2.4.18'

+

93.2 Using the Custom Test Generator

If you want to generate tests for languages other than Java or you are not happy with the +way the verifier builds Java tests, you can register your own implementation.

The SingleTestGenerator interface lets you register your own implementation. The +following code listing shows the SingleTestGenerator interface:

package org.springframework.cloud.contract.verifier.builder
+
+import org.springframework.cloud.contract.verifier.config.ContractVerifierConfigProperties
+import org.springframework.cloud.contract.verifier.file.ContractMetadata
+/**
+ * Builds a single test.
+ *
+ * @since 1.1.0
+ */
+interface SingleTestGenerator {
+
+	/**
+	 * Creates contents of a single test class in which all test scenarios from
+	 * the contract metadata should be placed.
+	 *
+	 * @param properties - properties passed to the plugin
+	 * @param listOfFiles - list of parsed contracts with additional metadata
+	 * @param className - the name of the generated test class
+	 * @param classPackage - the name of the package in which the test class should be stored
+	 * @param includedDirectoryRelativePath - relative path to the included directory
+	 * @return contents of a single test class
+	 */
+	String buildClass(ContractVerifierConfigProperties properties, Collection<ContractMetadata> listOfFiles,
+					  String className, String classPackage, String includedDirectoryRelativePath)
+
+	/**
+	 * Extension that should be appended to the generated test class. E.g. {@code .java} or {@code .php}
+	 *
+	 * @param properties - properties passed to the plugin
+	 */
+	String fileExtension(ContractVerifierConfigProperties properties)
+}

Again, you must provide a spring.factories file, such as the one shown in the following +example:

org.springframework.cloud.contract.verifier.builder.SingleTestGenerator=/
+com.example.MyGenerator

93.3 Using the Custom Stub Generator

If you want to generate stubs for stub servers other than WireMock, you can plug in your +own implementation of the StubGenerator interface. The following code listing shows the +StubGenerator interface:

package org.springframework.cloud.contract.verifier.converter
+
+import groovy.transform.CompileStatic
+import org.springframework.cloud.contract.spec.Contract
+import org.springframework.cloud.contract.verifier.file.ContractMetadata
+
+/**
+ * Converts contracts into their stub representation.
+ *
+ * @since 1.1.0
+ */
+@CompileStatic
+interface StubGenerator {
+
+	/**
+	 * Returns {@code true} if the converter can handle the file to convert it into a stub.
+	 */
+	boolean canHandleFileName(String fileName)
+
+	/**
+	 * Returns the collection of converted contracts into stubs. One contract can
+	 * result in multiple stubs.
+	 */
+	Map<Contract, String> convertContents(String rootName, ContractMetadata content)
+
+	/**
+	 * Returns the name of the converted stub file. If you have multiple contracts
+	 * in a single file then a prefix will be added to the generated file. If you
+	 * provide the {@link Contract#name} field then that field will override the
+	 * generated file name.
+	 *
+	 * Example: name of file with 2 contracts is {@code foo.groovy}, it will be
+	 * converted by the implementation to {@code foo.json}. The recursive file
+	 * converter will create two files {@code 0_foo.json} and {@code 1_foo.json}
+	 */
+	String generateOutputFileNameForInput(String inputFileName)
+}

Again, you must provide a spring.factories file, such as the one shown in the following +example:

# Stub converters
+org.springframework.cloud.contract.verifier.converter.StubGenerator=\
+org.springframework.cloud.contract.verifier.wiremock.DslToWireMockClientConverter

The default implementation is the WireMock stub generation.

[Tip]Tip

You can provide multiple stub generator implementations. For example, from a single +DSL, you can produce both WireMock stubs and Pact files.

93.4 Using the Custom Stub Runner

If you decide to use a custom stub generation, you also need a custom way of running +stubs with your different stub provider.

Assume that you use Moco to build your stubs and that +you have written a stub generator and placed your stubs in a JAR file.

In order for Stub Runner to know how to run your stubs, you have to define a custom +HTTP Stub server implementation, which might resemble the following example:

package org.springframework.cloud.contract.stubrunner.provider.moco
+
+import com.github.dreamhead.moco.bootstrap.arg.HttpArgs
+import com.github.dreamhead.moco.runner.JsonRunner
+import com.github.dreamhead.moco.runner.RunnerSetting
+import groovy.util.logging.Slf4j
+import org.springframework.cloud.contract.stubrunner.HttpServerStub
+import org.springframework.util.SocketUtils
+
+@Slf4j
+class MocoHttpServerStub implements HttpServerStub {
+
+	private boolean started
+	private JsonRunner runner
+	private int port
+
+	@Override
+	int port() {
+		if (!isRunning()) {
+			return -1
+		}
+		return port
+	}
+
+	@Override
+	boolean isRunning() {
+		return started
+	}
+
+	@Override
+	HttpServerStub start() {
+		return start(SocketUtils.findAvailableTcpPort())
+	}
+
+	@Override
+	HttpServerStub start(int port) {
+		this.port = port
+		return this
+	}
+
+	@Override
+	HttpServerStub stop() {
+		if (!isRunning()) {
+			return this
+		}
+		this.runner.stop()
+		return this
+	}
+
+	@Override
+	HttpServerStub registerMappings(Collection<File> stubFiles) {
+		List<RunnerSetting> settings = stubFiles.findAll { it.name.endsWith("json") }
+				.collect {
+			log.info("Trying to parse [{}]", it.name)
+			try {
+				return RunnerSetting.aRunnerSetting().withStream(it.newInputStream()).build()
+			} catch (Exception e) {
+				log.warn("Exception occurred while trying to parse file [{}]", it.name, e)
+				return null
+			}
+		}.findAll { it }
+		this.runner = JsonRunner.newJsonRunnerWithSetting(settings,
+				HttpArgs.httpArgs().withPort(this.port).build())
+		this.runner.run()
+		this.started = true
+		return this
+	}
+
+	@Override
+	String registeredMappings() {
+		return ""
+	}
+
+	@Override
+	boolean isAccepted(File file) {
+		return file.name.endsWith(".json")
+	}
+}

Then, you can register it in your spring.factories file, as shown in the following +example:

org.springframework.cloud.contract.stubrunner.HttpServerStub=\
+org.springframework.cloud.contract.stubrunner.provider.moco.MocoHttpServerStub

Now you can run stubs with Moco.

[Important]Important

If you do not provide any implementation, then the default (WireMock) +implementation is used. If you provide more than one, the first one on the list is used.

93.5 Using the Custom Stub Downloader

You can customize the way your stubs are downloaded by creating an implementation of the +StubDownloaderBuilder interface, as shown in the following example:

package com.example;
+
+class CustomStubDownloaderBuilder implements StubDownloaderBuilder {
+
+	@Override
+	public StubDownloader build(final StubRunnerOptions stubRunnerOptions) {
+		return new StubDownloader() {
+			@Override
+			public Map.Entry<StubConfiguration, File> downloadAndUnpackStubJar(
+					StubConfiguration config) {
+				File unpackedStubs = retrieveStubs();
+				return new AbstractMap.SimpleEntry<>(
+						new StubConfiguration(config.getGroupId(), config.getArtifactId(), version,
+								config.getClassifier()), unpackedStubs);
+			}
+
+			File retrieveStubs() {
+			    // here goes your custom logic to provide a folder where all the stubs reside
+			}
+}

Then you can register it in your spring.factories file, as shown in the following +example:

# Example of a custom Stub Downloader Provider
+org.springframework.cloud.contract.stubrunner.StubDownloaderBuilder=\
+com.example.CustomStubDownloaderBuilder

Now you can pick a folder with the source of your stubs.

[Important]Important

If you do not provide any implementation, then the default is used. +If you use the repositoryRoot property or the workOffline flag, then an Aether-based +implementation that downloads stubs from a remote repository is used. If you do not +provide these values, the ClasspathStubProvider (which will scan the classpath) is +used. If you provide more than one, then the first one on the list is used.

Prev Up Next
92. Customization Home 94. Spring Cloud Contract WireMock
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77. Writing Groovy Scripts and Running Applications
Prev Part X. Spring Boot Cloud CLI Next

77. Writing Groovy Scripts and Running Applications

Spring Cloud CLI has support for most of the Spring Cloud declarative +features, such as the @Enable* class of annotations. For example, +here is a fully functional Eureka server

app.groovy.  +

@EnableEurekaServer
+class Eureka {}

+

which you can run from the command line like this

$ spring run app.groovy

To include additional dependencies, often it suffices just to add the +appropriate feature-enabling annotation, e.g. @EnableConfigServer, +@EnableOAuth2Sso or @EnableEurekaClient. To manually include a +dependency you can use a @Grab with the special "Spring Boot" short +style artifact co-ordinates, i.e. with just the artifact ID (no need +for group or version information), e.g. to set up a client app to +listen on AMQP for management events from the Spring CLoud Bus:

app.groovy.  +

@Grab('spring-cloud-starter-bus-amqp')
+@RestController
+class Service {
+  @RequestMapping('/')
+  def home() { [message: 'Hello'] }
+}

+

Prev Up Next
76. Running Spring Cloud Services in Development Home 78. Encryption and Decryption
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29. Content Type and Transformation
Prev Part IV. Spring Cloud Stream Next

29. Content Type and Transformation

To allow you to propagate information about the content type of produced messages, Spring Cloud Stream attaches, by default, a contentType header to outbound messages. +For middleware that does not directly support headers, Spring Cloud Stream provides its own mechanism of automatically wrapping outbound messages in an envelope of its own. +For middleware that does support headers, Spring Cloud Stream applications may receive messages with a given content type from non-Spring Cloud Stream applications.

Spring Cloud Stream can handle messages based on this information in two ways:

  • Through its contentType settings on inbound and outbound channels
  • Through its argument mapping performed for methods annotated with @StreamListener

Spring Cloud Stream allows you to declaratively configure type conversion for inputs and outputs using the spring.cloud.stream.bindings.<channelName>.content-type property of a binding. +Note that general type conversion may also be accomplished easily by using a transformer inside your application. +Currently, Spring Cloud Stream natively supports the following type conversions commonly used in streams:

  • JSON to/from POJO
  • JSON to/from org.springframework.tuple.Tuple
  • Object to/from byte[] : Either the raw bytes serialized for remote transport, bytes emitted by an application, or converted to bytes using Java serialization(requires the object to be Serializable)
  • String to/from byte[]
  • Object to plain text (invokes the object’s toString() method)

Where JSON represents either a byte array or String payload containing JSON. +Currently, Objects may be converted from a JSON byte array or String. +Converting to JSON always produces a String.

If no content-type property is set on an outbound channel, Spring Cloud Stream will serialize the payload using a serializer based on the Kryo serialization framework. +Deserializing messages at the destination requires the payload class to be present on the receiver’s classpath.

29.1 MIME types

content-type values are parsed as media types, e.g., application/json or text/plain;charset=UTF-8. +MIME types are especially useful for indicating how to convert to String or byte[] content. +Spring Cloud Stream also uses MIME type format to represent Java types, using the general type application/x-java-object with a type parameter. +For example, application/x-java-object;type=java.util.Map or application/x-java-object;type=com.bar.Foo can be set as the content-type property of an input binding. +In addition, Spring Cloud Stream provides custom MIME types, notably, application/x-spring-tuple to specify a Tuple.

29.2 MIME types and Java types

The type conversions Spring Cloud Stream provides out of the box are summarized in the following table: +'Source Payload' means the payload before conversion and 'Target Payload' means the 'payload' after conversion. +The type conversion can occur either on the 'producer' side (output) or at the 'consumer' side (input).

Source PayloadTarget Payloadcontent-type header (source message)content-type header (after conversion)Comments

POJO

JSON String

ignored

application/json

 

Tuple

JSON String

ignored

application/json

JSON is tailored for Tuple

POJO

String (toString())

ignored

text/plain, java.lang.String

 

POJO

byte[] (java.io serialized)

ignored

application/x-java-serialized-object

 

JSON byte[] or String

POJO

application/json (or none)

application/x-java-object

 

byte[] or String

Serializable

application/x-java-serialized-object

application/x-java-object

 

JSON byte[] or String

Tuple

application/json (or none)

application/x-spring-tuple

 

byte[]

String

any

text/plain, java.lang.String

will apply any Charset specified in the content-type header

String

byte[]

any

application/octet-stream

will apply any Charset specified in the content-type header

[Note]Note

Conversion applies to payloads that require type conversion. +For example, if an application produces an XML string with outputType=application/json, the payload will not be converted from XML to JSON. +This is because the payload send to the outbound channel is already a String so no conversion will be applied at runtime. +It is also important to note that when using the default serialization mechanism, the payload class must be shared between the sending and receiving application, and compatible with the binary content. +This can create issues when application code changes independently in the two applications, as the binary format and code may become incompatible.

[Tip]Tip

While conversion is supported for both inbound and outbound channels, it is especially recommended to be used for the conversion of outbound messages. +For the conversion of inbound messages, especially when the target is a POJO, the @StreamListener support will perform the conversion automatically.

29.3 Customizing message conversion

Besides the conversions that it supports out of the box, Spring Cloud Stream also supports registering your own message conversion implementations. +This allows you to send and receive data in a variety of custom formats, including binary, and associate them with specific contentTypes. +Spring Cloud Stream registers all the beans of type org.springframework.messaging.converter.MessageConverter as custom message converters along with the out of the box message converters.

If your message converter needs to work with a specific content-type and target class (for both input and output), then the message converter needs to extend org.springframework.messaging.converter.AbstractMessageConverter. +For conversion when using @StreamListener, a message converter that implements org.springframework.messaging.converter.MessageConverter would suffice.

Here is an example of creating a message converter bean (with the content-type application/bar) inside a Spring Cloud Stream application:

@EnableBinding(Sink.class)
+@SpringBootApplication
+public static class SinkApplication {
+
+  ...
+
+  @Bean
+  public MessageConverter customMessageConverter() {
+    return new MyCustomMessageConverter();
+  }
public class MyCustomMessageConverter extends AbstractMessageConverter {
+
+	public MyCustomMessageConverter() {
+		super(new MimeType("application", "bar"));
+	}
+
+	@Override
+  protected boolean supports(Class<?> clazz) {
+    return (Bar.class == clazz);
+  }
+
+	@Override
+	protected Object convertFromInternal(Message<?> message, Class<?> targetClass, Object conversionHint) {
+		Object payload = message.getPayload();
+		return (payload instanceof Bar ? payload : new Bar((byte[]) payload));
+	}
+}

Spring Cloud Stream also provides support for Avro-based converters and schema evolution. +See the specific section for details.

29.4 @StreamListener and Message Conversion

The @StreamListener annotation provides a convenient way for converting incoming messages without the need to specify the content type of an input channel. +During the dispatching process to methods annotated with @StreamListener, a conversion will be applied automatically if the argument requires it.

For example, let’s consider a message with the String content {"greeting":"Hello, world"} and a content-type header of application/json is received on the input channel. +Let us consider the following application that receives it:

public class GreetingMessage {
+
+  String greeting;
+
+  public String getGreeting() {
+    return greeting;
+  }
+
+  public void setGreeting(String greeting) {
+    this.greeting = greeting;
+  }
+}
+
+@EnableBinding(Sink.class)
+@EnableAutoConfiguration
+public static class GreetingSink {
+
+		@StreamListener(Sink.INPUT)
+		public void receive(Greeting greeting) {
+			// handle Greeting
+		}
+	}

The argument of the method will be populated automatically with the POJO containing the unmarshalled form of the JSON String.

Prev Up Next
28. Configuration Options Home 30. Schema Evolution Support
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22. Metrics: Spectator, Servo, and Atlas
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22. Metrics: Spectator, Servo, and Atlas

When used together, Spectator/Servo and Atlas provide a near real-time operational insight platform.

Spectator and Servo are Netflix’s metrics collection libraries. Atlas is a Netflix metrics backend to manage dimensional time series data.

Servo served Netflix for several years and is still usable, but is gradually being phased out in favor of Spectator, which is only designed to work with Java 8. Spring Cloud Netflix provides support for both, but Java 8 based applications are encouraged to use Spectator.

To enable Servo you must set spring.metrics.servo.enabled to true.

22.1 Dimensional vs. Hierarchical Metrics

Spring Boot Actuator metrics are hierarchical and metrics are separated only by name. These names often follow a naming convention that embeds key/value attribute pairs (dimensions) into the name separated by periods. Consider the following metrics for two endpoints, root and star-star:

{
+    "counter.status.200.root": 20,
+    "counter.status.400.root": 3,
+    "counter.status.200.star-star": 5,
+}

The first metric gives us a normalized count of successful requests against the root endpoint per unit of time. But what if the system had 20 endpoints and you want to get a count of successful requests against all the endpoints? Some hierarchical metrics backends would allow you to specify a wild card such as counter.status.200.* that would read all 20 metrics and aggregate the results. Alternatively, you could provide a HandlerInterceptorAdapter that intercepts and records a metric like counter.status.200.all for all successful requests irrespective of the endpoint, but now you must write 20+1 different metrics. Similarly if you want to know the total number of successful requests for all endpoints in the service, you could specify a wild card such as counter.status.2*.*.

Even in the presence of wildcarding support on a hierarchical metrics backend, naming consistency can be difficult. Specifically the position of these tags in the name string can slip with time, breaking queries. For example, suppose we add an additional dimension to the hierarchical metrics above for HTTP method. Then counter.status.200.root becomes counter.status.200.method.get.root, etc. Our counter.status.200.* suddenly no longer has the same semantic meaning. Furthermore, if the new dimension is not applied uniformly across the codebase, certain queries may become impossible. This can quickly get out of hand.

Netflix metrics are tagged (a.k.a. dimensional). Each metric has a name, but this single named metric can contain multiple statistics and 'tag' key/value pairs that allows more querying flexibility. In fact, the statistics themselves are recorded in a special tag.

Recorded with Netflix Servo or Spectator, a timer for the root endpoint described above contains 4 statistics per status code, where the count statistic is identical to Spring Boot Actuator’s counter. In the event that we have encountered an HTTP 200 and 400 thus far, there will be 8 available data points:

{
+    "root(status=200,stastic=count)": 20,
+    "root(status=200,stastic=max)": 0.7265630630000001,
+    "root(status=200,stastic=totalOfSquares)": 0.04759702862580789,
+    "root(status=200,stastic=totalTime)": 0.2093076914666667,
+    "root(status=400,stastic=count)": 1,
+    "root(status=400,stastic=max)": 0,
+    "root(status=400,stastic=totalOfSquares)": 0,
+    "root(status=400,stastic=totalTime)": 0,
+}

22.2 Default Metrics Collection

Without any additional dependencies or configuration, a Spring Cloud based service will autoconfigure a Servo MonitorRegistry and begin collecting metrics on every Spring MVC request. By default, a Servo timer with the name rest will be recorded for each MVC request which is tagged with:

  1. HTTP method
  2. HTTP status (e.g. 200, 400, 500)
  3. URI (or "root" if the URI is empty), sanitized for Atlas
  4. The exception class name, if the request handler threw an exception
  5. The caller, if a request header with a key matching netflix.metrics.rest.callerHeader is set on the request. There is no default key for netflix.metrics.rest.callerHeader. You must add it to your application properties if you wish to collect caller information.

Set the netflix.metrics.rest.metricName property to change the name of the metric from rest to a name you provide.

If Spring AOP is enabled and org.aspectj:aspectjweaver is present on your runtime classpath, Spring Cloud will also collect metrics on every client call made with RestTemplate. A Servo timer with the name of restclient will be recorded for each MVC request which is tagged with:

  1. HTTP method
  2. HTTP status (e.g. 200, 400, 500), "CLIENT_ERROR" if the response returned null, or "IO_ERROR" if an IOException occurred during the execution of the RestTemplate method
  3. URI, sanitized for Atlas
  4. Client name
[Warning]Warning

Avoid using hardcoded url parameters within RestTemplate. When targeting dynamic endpoints use URL variables. This will avoid potential "GC Overhead Limit Reached" issues where ServoMonitorCache treats each url as a unique key.

// recommended
+String orderid = "1";
+restTemplate.getForObject("http://testclient/orders/{orderid}", String.class, orderid)
+
+// avoid
+restTemplate.getForObject("http://testclient/orders/1", String.class)

22.3 Metrics Collection: Spectator

To enable Spectator metrics, include a dependency on spring-boot-starter-spectator:

    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-starter-netflix-spectator</artifactId>
+    </dependency>

In Spectator parlance, a meter is a named, typed, and tagged configuration and a metric represents the value of a given meter at a point in time. Spectator meters are created and controlled by a registry, which currently has several different implementations. Spectator provides 4 meter types: counter, timer, gauge, and distribution summary.

Spring Cloud Spectator integration configures an injectable com.netflix.spectator.api.Registry instance for you. Specifically, it configures a ServoRegistry instance in order to unify the collection of REST metrics and the exporting of metrics to the Atlas backend under a single Servo API. Practically, this means that your code may use a mixture of Servo monitors and Spectator meters and both will be scooped up by Spring Boot Actuator MetricReader instances and both will be shipped to the Atlas backend.

22.3.1 Spectator Counter

A counter is used to measure the rate at which some event is occurring.

// create a counter with a name and a set of tags
+Counter counter = registry.counter("counterName", "tagKey1", "tagValue1", ...);
+counter.increment(); // increment when an event occurs
+counter.increment(10); // increment by a discrete amount

The counter records a single time-normalized statistic.

22.3.2 Spectator Timer

A timer is used to measure how long some event is taking. Spring Cloud automatically records timers for Spring MVC requests and conditionally RestTemplate requests, which can later be used to create dashboards for request related metrics like latency:

Figure 22.1. Request Latency

RequestLatency

// create a timer with a name and a set of tags
+Timer timer = registry.timer("timerName", "tagKey1", "tagValue1", ...);
+
+// execute an operation and time it at the same time
+T result = timer.record(() -> fooReturnsT());
+
+// alternatively, if you must manually record the time
+Long start = System.nanoTime();
+T result = fooReturnsT();
+timer.record(System.nanoTime() - start, TimeUnit.NANOSECONDS);

The timer simultaneously records 4 statistics: count, max, totalOfSquares, and totalTime. The count statistic will always match the single normalized value provided by a counter if you had called increment() once on the counter for each time you recorded a timing, so it is rarely necessary to count and time separately for a single operation.

For long running operations, Spectator provides a special LongTaskTimer.

22.3.3 Spectator Gauge

Gauges are used to determine some current value like the size of a queue or number of threads in a running state. Since gauges are sampled, they provide no information about how these values fluctuate between samples.

The normal use of a gauge involves registering the gauge once in initialization with an id, a reference to the object to be sampled, and a function to get or compute a numeric value based on the object. The reference to the object is passed in separately and the Spectator registry will keep a weak reference to the object. If the object is garbage collected, then Spectator will automatically drop the registration. See the note in Spectator’s documentation about potential memory leaks if this API is misused.

// the registry will automatically sample this gauge periodically
+registry.gauge("gaugeName", pool, Pool::numberOfRunningThreads);
+
+// manually sample a value in code at periodic intervals -- last resort!
+registry.gauge("gaugeName", Arrays.asList("tagKey1", "tagValue1", ...), 1000);

22.3.4 Spectator Distribution Summaries

A distribution summary is used to track the distribution of events. It is similar to a timer, but more general in that the size does not have to be a period of time. For example, a distribution summary could be used to measure the payload sizes of requests hitting a server.

// the registry will automatically sample this gauge periodically
+DistributionSummary ds = registry.distributionSummary("dsName", "tagKey1", "tagValue1", ...);
+ds.record(request.sizeInBytes());

22.4 Metrics Collection: Servo

[Warning]Warning

If your code is compiled on Java 8, please use Spectator instead of Servo as Spectator is destined to replace Servo entirely in the long term.

In Servo parlance, a monitor is a named, typed, and tagged configuration and a metric represents the value of a given monitor at a point in time. Servo monitors are logically equivalent to Spectator meters. Servo monitors are created and controlled by a MonitorRegistry. In spite of the above warning, Servo does have a wider array of monitor options than Spectator has meters.

Spring Cloud integration configures an injectable com.netflix.servo.MonitorRegistry instance for you. Once you have created the appropriate Monitor type in Servo, the process of recording data is wholly similar to Spectator.

22.4.1 Creating Servo Monitors

If you are using the Servo MonitorRegistry instance provided by Spring Cloud (specifically, an instance of DefaultMonitorRegistry), Servo provides convenience classes for retrieving counters and timers. These convenience classes ensure that only one Monitor is registered for each unique combination of name and tags.

To manually create a Monitor type in Servo, especially for the more exotic monitor types for which convenience methods are not provided, instantiate the appropriate type by providing a MonitorConfig instance:

MonitorConfig config = MonitorConfig.builder("timerName").withTag("tagKey1", "tagValue1").build();
+
+// somewhere we should cache this Monitor by MonitorConfig
+Timer timer = new BasicTimer(config);
+monitorRegistry.register(timer);

22.5 Metrics Backend: Atlas

Atlas was developed by Netflix to manage dimensional time series data for near real-time operational insight. Atlas features in-memory data storage, allowing it to gather and report very large numbers of metrics, very quickly.

Atlas captures operational intelligence. Whereas business intelligence is data gathered for analyzing trends over time, operational intelligence provides a picture of what is currently happening within a system.

Spring Cloud provides a spring-cloud-starter-netflix-atlas that has all the dependencies you need. Then just annotate your Spring Boot application with @EnableAtlas and provide a location for your running Atlas server with the netflix.atlas.uri property.

22.5.1 Global tags

Spring Cloud enables you to add tags to every metric sent to the Atlas backend. Global tags can be used to separate metrics by application name, environment, region, etc.

Each bean implementing AtlasTagProvider will contribute to the global tag list:

@Bean
+AtlasTagProvider atlasCommonTags(
+    @Value("${spring.application.name}") String appName) {
+  return () -> Collections.singletonMap("app", appName);
+}

22.5.2 Using Atlas

To bootstrap a in-memory standalone Atlas instance:

$ curl -LO https://github.com/Netflix/atlas/releases/download/v1.4.2/atlas-1.4.2-standalone.jar
+$ java -jar atlas-1.4.2-standalone.jar
[Tip]Tip

An Atlas standalone node running on an r3.2xlarge (61GB RAM) can handle roughly 2 million metrics per minute for a given 6 hour window.

Once running and you have collected a handful of metrics, verify that your setup is correct by listing tags on the Atlas server:

$ curl http://ATLAS/api/v1/tags
[Tip]Tip

After executing several requests against your service, you can gather some very basic information on the request latency of every request by pasting the following url in your browser: http://ATLAS/api/v1/graph?q=name,rest,:eq,:avg

The Atlas wiki contains a compilation of sample queries for various scenarios.

Make sure to check out the alerting philosophy and docs on using double exponential smoothing to generate dynamic alert thresholds.

22.6 Retrying Failed Requests

Spring Cloud Netflix offers a variety of ways to make HTTP requests. You can use a load balanced +RestTemplate, Ribbon, or Feign. No matter how you choose to your HTTP requests, there is always +a chance the request may fail. When a request fails you may want to have the request retried +automatically. To accomplish this when using Sping Cloud Netflix you need to include +Spring Retry on your application’s classpath. +When Spring Retry is present load balanced RestTemplates, Feign, and Zuul will automatically +retry any failed requests (assuming you configuration allows it to).

22.6.1 BackOff Policies

By default no backoff policy is used when retrying requests. If you would like to configure +a backoff policy you will need to create a bean of type LoadBalancedBackOffPolicyFactory +which will be used to create a BackOffPolicy for a given service.

@Configuration
+public class MyConfiguration {
+    @Bean
+    LoadBalancedBackOffPolicyFactory backOffPolciyFactory() {
+        return new LoadBalancedBackOffPolicyFactory() {
+            @Override
+            public BackOffPolicy createBackOffPolicy(String service) {
+                return new ExponentialBackOffPolicy();
+            }
+        };
+    }
+}

22.6.2 Configuration

Anytime Ribbon is used with Spring Retry you can control the retry functionality by configuring +certain Ribbon properties. The properties you can use are +client.ribbon.MaxAutoRetries, client.ribbon.MaxAutoRetriesNextServer, and +client.ribbon.OkToRetryOnAllOperations. See the Ribbon documentation +for a description of what there properties do.

[Warning]Warning

Enabling client.ribbon.OkToRetryOnAllOperations includes retring POST requests wich can have a impact +on the server’s resources due to the buffering of the request’s body.

In addition you may want to retry requests when certain status codes are returned in the +response. You can list the response codes you would like the Ribbon client to retry using the + property clientName.ribbon.retryableStatusCodes. For example

clientName:
+  ribbon:
+    retryableStatusCodes: 404,502

You can also create a bean of type LoadBalancedRetryPolicy and implement the retryableStatusCode +method to determine whether you want to retry a request given the status code.

22.6.3 Zuul

You can turn off Zuul’s retry functionality by setting zuul.retryable to false. You +can also disable retry functionality on route by route basis by setting +zuul.routes.routename.retryable to false.

Prev Up Next
21. RxJava with Spring MVC Home 23. HTTP Clients
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21. RxJava with Spring MVC
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21. RxJava with Spring MVC

Spring Cloud Netflix includes RxJava.

RxJava is a Java VM implementation of Reactive Extensions: a library for composing asynchronous and event-based programs by using observable sequences.

Spring Cloud Netflix provides support for returning rx.Single objects from Spring MVC Controllers. It also supports using rx.Observable objects for Server-sent events (SSE). This can be very convenient if your internal APIs are already built using RxJava (see Section 17.4, “Feign Hystrix Support” for examples).

Here are some examples of using rx.Single:

@RequestMapping(method = RequestMethod.GET, value = "/single")
+public Single<String> single() {
+	return Single.just("single value");
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/singleWithResponse")
+public ResponseEntity<Single<String>> singleWithResponse() {
+	return new ResponseEntity<>(Single.just("single value"),
+			HttpStatus.NOT_FOUND);
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/singleCreatedWithResponse")
+public Single<ResponseEntity<String>> singleOuterWithResponse() {
+	return Single.just(new ResponseEntity<>("single value", HttpStatus.CREATED));
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/throw")
+public Single<Object> error() {
+	return Single.error(new RuntimeException("Unexpected"));
+}

If you have an Observable, rather than a single, you can use .toSingle() or .toList().toSingle(). Here are some examples:

@RequestMapping(method = RequestMethod.GET, value = "/single")
+public Single<String> single() {
+	return Observable.just("single value").toSingle();
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/multiple")
+public Single<List<String>> multiple() {
+	return Observable.just("multiple", "values").toList().toSingle();
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/responseWithObservable")
+public ResponseEntity<Single<String>> responseWithObservable() {
+
+	Observable<String> observable = Observable.just("single value");
+	HttpHeaders headers = new HttpHeaders();
+	headers.setContentType(APPLICATION_JSON_UTF8);
+	return new ResponseEntity<>(observable.toSingle(), headers, HttpStatus.CREATED);
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/timeout")
+public Observable<String> timeout() {
+	return Observable.timer(1, TimeUnit.MINUTES).map(new Func1<Long, String>() {
+		@Override
+		public String call(Long aLong) {
+			return "single value";
+		}
+	});
+}

If you have a streaming endpoint and client, SSE could be an option. To convert rx.Observable to a Spring SseEmitter use RxResponse.sse(). Here are some examples:

@RequestMapping(method = RequestMethod.GET, value = "/sse")
+public SseEmitter single() {
+	return RxResponse.sse(Observable.just("single value"));
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/messages")
+public SseEmitter messages() {
+	return RxResponse.sse(Observable.just("message 1", "message 2", "message 3"));
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/events")
+public SseEmitter event() {
+	return RxResponse.sse(APPLICATION_JSON_UTF8,
+			Observable.just(new EventDto("Spring io", getDate(2016, 5, 19)),
+					new EventDto("SpringOnePlatform", getDate(2016, 8, 1))));
+}
Prev Up Next
20. Polyglot support with Sidecar Home 22. Metrics: Spectator, Servo, and Atlas
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Spring Cloud provides tools for developers to quickly build some of +the common patterns in distributed systems (e.g. configuration +management, service discovery, circuit breakers, intelligent routing, +micro-proxy, control bus). Coordination of +distributed systems leads to boiler plate patterns, and using Spring +Cloud developers can quickly stand up services and applications that +implement those patterns. They will work well in any distributed +environment, including the developer’s own laptop, bare metal data +centres, and managed platforms such as Cloud Foundry.

Version: 1.3.8.RELEASE

Prev   Next
Spring Cloud Home 1. Features
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30. Schema Evolution Support
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30. Schema Evolution Support

Spring Cloud Stream provides support for schema evolution so that the data can be evolved over time and still work with older or newer producers and consumers and vice versa. +Most serialization models, especially the ones that aim for portability across different platforms and languages, rely on a schema that describes how the data is serialized in the binary payload. +In order to serialize the data and then to interpret it, both the sending and receiving sides must have access to a schema that describes the binary format. +In certain cases, the schema can be inferred from the payload type on serialization or from the target type on deserialization. +However, many applications benefit from having access to an explicit schema that describes the binary data format. +A schema registry lets you store schema information in a textual format (typically JSON) and makes that information accessible to various applications that need it to receive and send data in binary format. +A schema is referenceable as a tuple consisting of:

  • A subject that is the logical name of the schema
  • The schema version
  • The schema format, which describes the binary format of the data

This following sections goes through the details of various components involved in schema evolution process.

30.1 Schema Registry Client

The client-side abstraction for interacting with schema registry servers is the SchemaRegistryClient interface, which has the following structure:

public interface SchemaRegistryClient {
+
+    SchemaRegistrationResponse register(String subject, String format, String schema);
+
+    String fetch(SchemaReference schemaReference);
+
+    String fetch(Integer id);
+
+}

Spring Cloud Stream provides out-of-the-box implementations for interacting with its own schema server and for interacting with the Confluent Schema Registry.

A client for the Spring Cloud Stream schema registry can be configured by using the @EnableSchemaRegistryClient, as follows:

  @EnableBinding(Sink.class)
+  @SpringBootApplication
+  @EnableSchemaRegistryClient
+  public static class AvroSinkApplication {
+    ...
+  }
[Note]Note

The default converter is optimized to cache not only the schemas from the remote server but also the parse() and toString() methods, which are quite expensive. +Because of this, it uses a DefaultSchemaRegistryClient that does not cache responses. +If you intend to change the default behavior, you can use the client directly on your code and override it to the desired outcome. +To do so, you have to add the property spring.cloud.stream.schemaRegistryClient.cached=true to your application properties.

30.1.1 Schema Registry Client Properties

The Schema Registry Client supports the following properties:

spring.cloud.stream.schemaRegistryClient.endpoint
The location of the schema-server. +When setting this, use a full URL, including protocol (http or https) , port, and context path.
Default
http://localhost:8990/
spring.cloud.stream.schemaRegistryClient.cached
Whether the client should cache schema server responses. +Normally set to false, as the caching happens in the message converter. +Clients using the schema registry client should set this to true.
Default
true

30.2 Avro Schema Registry Client Message Converters

For applications that have a SchemaRegistryClient bean registered with the application context, Spring Cloud Stream auto configures an Apache Avro message converter for schema management. +This eases schema evolution, as applications that receive messages can get easy access to a writer schema that can be reconciled with their own reader schema.

For outbound messages, if the content type of the channel is set to application/*+avro, the MessageConverter is activated, as shown in the following example:

spring.cloud.stream.bindings.output.contentType=application/*+avro

During the outbound conversion, the message converter tries to infer the schema of each outbound messages (based on its type) and register it to a subject (based on the payload type) by using the SchemaRegistryClient. +If an identical schema is already found, then a reference to it is retrieved. +If not, the schema is registered, and a new version number is provided. +The message is sent with a contentType header by using the following scheme: application/[prefix].[subject].v[version]+avro, where prefix is configurable and subject is deduced from the payload type.

For example, a message of the type User might be sent as a binary payload with a content type of application/vnd.user.v2+avro, where user is the subject and 2 is the version number.

When receiving messages, the converter infers the schema reference from the header of the incoming message and tries to retrieve it. The schema is used as the writer schema in the deserialization process.

30.2.1 Avro Schema Registry Message Converter Properties

If you have enabled Avro based schema registry client by setting spring.cloud.stream.bindings.output.contentType=application/*+avro, you can customize the behavior of the registration by setting the following properties.

spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled

Enable if you want the converter to use reflection to infer a Schema from a POJO.

Default: false

spring.cloud.stream.schema.avro.readerSchema
Avro compares schema versions by looking at a writer schema (origin payload) and a reader schema (your application payload). See the Avro documentation for more information. If set, this overrides any lookups at the schema server and uses the local schema as the reader schema. +Default: null
spring.cloud.stream.schema.avro.schemaLocations

Registers any .avsc files listed in this property with the Schema Server.

Default: empty

spring.cloud.stream.schema.avro.prefix

The prefix to be used on the Content-Type header.

Default: vnd

30.3 Apache Avro Message Converters

Spring Cloud Stream provides support for schema-based message converters through its spring-cloud-stream-schema module. +Currently, the only serialization format supported out of the box for schema-based message converters is Apache Avro, with more formats to be added in future versions.

The spring-cloud-stream-schema module contains two types of message converters that can be used for Apache Avro serialization:

  • Converters that use the class information of the serialized or deserialized objects or a schema with a location known at startup.
  • Converters that use a schema registry. They locate the schemas at runtime and dynamically register new schemas as domain objects evolve.

30.4 Converters with Schema Support

The AvroSchemaMessageConverter supports serializing and deserializing messages either by using a predefined schema or by using the schema information available in the class (either reflectively or contained in the SpecificRecord). +If you provide a custom converter, then the default AvroSchemaMessageConverter bean is not created. The following example shows a custom converter:

To use custom converters, you can simply add it to the application context, optionally specifying one or more MimeTypes with which to associate it. +The default MimeType is application/avro.

If the target type of the conversion is a GenericRecord, a schema must be set.

The following example shows how to configure a converter in a sink application by registering the Apache Avro MessageConverter without a predefined schema. +In this example, note that the mime type value is avro/bytes, not the default application/avro.

@EnableBinding(Sink.class)
+@SpringBootApplication
+public static class SinkApplication {
+
+  ...
+
+  @Bean
+  public MessageConverter userMessageConverter() {
+      return new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes"));
+  }
+}

Conversely, the following application registers a converter with a predefined schema (found on the classpath):

@EnableBinding(Sink.class)
+@SpringBootApplication
+public static class SinkApplication {
+
+  ...
+
+  @Bean
+  public MessageConverter userMessageConverter() {
+      AvroSchemaMessageConverter converter = new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes"));
+      converter.setSchemaLocation(new ClassPathResource("schemas/User.avro"));
+      return converter;
+  }
+}

30.5 Schema Registry Server

Spring Cloud Stream provides a schema registry server implementation. +To use it, you can add the spring-cloud-stream-schema-server artifact to your project and use the @EnableSchemaRegistryServer annotation, which adds the schema registry server REST controller to your application. +This annotation is intended to be used with Spring Boot web applications, and the listening port of the server is controlled by the server.port property. +The spring.cloud.stream.schema.server.path property can be used to control the root path of the schema server (especially when it is embedded in other applications). +The spring.cloud.stream.schema.server.allowSchemaDeletion boolean property enables the deletion of a schema. By default, this is disabled.

The schema registry server uses a relational database to store the schemas. +By default, it uses an embedded database. +You can customize the schema storage by using the Spring Boot SQL database and JDBC configuration options.

The following example shows a Spring Boot application that enables the schema registry:

@SpringBootApplication
+@EnableSchemaRegistryServer
+public class SchemaRegistryServerApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(SchemaRegistryServerApplication.class, args);
+    }
+}

30.5.1 Schema Registry Server API

The Schema Registry Server API consists of the following operations:

Registering a New Schema

To register a new schema, send a POST request to the / endpoint.

The / accepts a JSON payload with the following fields:

  • subject: The schema subject
  • format: The schema format
  • definition: The schema definition

Its response is a schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Retrieving an Existing Schema by Subject, Format, and Version

To retrieve an existing schema by subject, format, and version, send GET request to the /{subject}/{format}/{version} endpoint.

Its response is a schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Retrieving an Existing Schema by Subject and Format

To retrieve an existing schema by subject and format, send a GET request to the /subject/format endpoint.

Its response is a list of schemas with each schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Retrieving an Existing Schema by ID

To retrieve a schema by its ID, send a GET request to the /schemas/{id} endpoint.

Its response is a schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Deleting a Schema by Subject, Format, and Version

To delete a schema identified by its subject, format, and version, send a DELETE request to the /{subject}/{format}/{version} endpoint.

Deleting a Schema by ID

To delete a schema by its ID, send a DELETE request to the /schemas/{id} endpoint.

Deleting a Schema by Subject

DELETE /{subject}

Delete existing schemas by their subject.

[Note]Note

This note applies to users of Spring Cloud Stream 1.1.0.RELEASE only. +Spring Cloud Stream 1.1.0.RELEASE used the table name, schema, for storing Schema objects. Schema is a keyword in a number of database implementations. +To avoid any conflicts in the future, starting with 1.1.1.RELEASE, we have opted for the name SCHEMA_REPOSITORY for the storage table. +Any Spring Cloud Stream 1.1.0.RELEASE users who upgrade should migrate their existing schemas to the new table before upgrading.

30.5.2 Using Confluent’s Schema Registry

The default configuration creates a DefaultSchemaRegistryClient bean. +If you want to use the Confluent schema registry, you need to create a bean of type ConfluentSchemaRegistryClient, which supersedes the one configured by default by the framework. The following example shows how to create such a bean:

@Bean
+public SchemaRegistryClient schemaRegistryClient(@Value("${spring.cloud.stream.schemaRegistryClient.endpoint}") String endpoint){
+  ConfluentSchemaRegistryClient client = new ConfluentSchemaRegistryClient();
+  client.setEndpoint(endpoint);
+  return client;
+}
[Note]Note

The ConfluentSchemaRegistryClient is tested against Confluent platform version 4.0.0.

30.6 Schema Registration and Resolution

To better understand how Spring Cloud Stream registers and resolves new schemas and its use of Avro schema comparison features, we provide two separate subsections:

30.6.1 Schema Registration Process (Serialization)

The first part of the registration process is extracting a schema from the payload that is being sent over a channel. +Avro types such as SpecificRecord or GenericRecord already contain a schema, which can be retrieved immediately from the instance. +In the case of POJOs, a schema is inferred if the spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled property is set to true (the default).

Figure 30.1. Schema Writer Resolution Process

schema resolution

Ones a schema is obtained, the converter loads its metadata (version) from the remote server. +First, it queries a local cache. If no result is found, it submits the data to the server, which replies with versioning information. +The converter always caches the results to avoid the overhead of querying the Schema Server for every new message that needs to be serialized.

Figure 30.2. Schema Registration Process

registration

With the schema version information, the converter sets the contentType header of the message to carry the version information — for example: application/vnd.user.v1+avro.

30.6.2 Schema Resolution Process (Deserialization)

When reading messages that contain version information (that is, a contentType header with a scheme like the one described under “Section 30.6.1, “Schema Registration Process (Serialization)””), the converter queries the Schema server to fetch the writer schema of the message. +Once it has found the correct schema of the incoming message, it retrieves the reader schema and, by using Avro’s schema resolution support, reads it into the reader definition (setting defaults and any missing properties).

Figure 30.3. Schema Reading Resolution Process

schema reading

[Note]Note

You should understand the difference between a writer schema (the application that wrote the message) and a reader schema (the receiving application). +We suggest taking a moment to read the Avro terminology and understand the process. +Spring Cloud Stream always fetches the writer schema to determine how to read a message. +If you want to get Avro’s schema evolution support working, you need to make sure that a readerSchema was properly set for your application.

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61. Consul Agent
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61. Consul Agent

A Consul Agent client must be available to all Spring Cloud Consul applications. By default, the Agent client is expected to be at localhost:8500. See the Agent documentation for specifics on how to start an Agent client and how to connect to a cluster of Consul Agent Servers. For development, after you have installed consul, you may start a Consul Agent using the following command:

./src/main/bash/local_run_consul.sh

This will start an agent in server mode on port 8500, with the ui available at http://localhost:8500

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65. Spring Cloud Bus with Consul
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65. Spring Cloud Bus with Consul

65.1 How to activate

To get started with the Consul Bus use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-bus. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.

See the Spring Cloud Bus documentation for the available actuator endpoints and howto send custom messages.

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63. Distributed Configuration with Consul
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63. Distributed Configuration with Consul

Consul provides a Key/Value Store for storing configuration and other metadata. Spring Cloud Consul Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config folder by default. Multiple PropertySource instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created:

config/testApp,dev/
+config/testApp/
+config/application,dev/
+config/application/

The most specific property source is at the top, with the least specific at the bottom. Properties in the config/application folder are applicable to all applications using consul for configuration. Properties in the config/testApp folder are only available to the instances of the service named "testApp".

Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh will cause the configuration to be reloaded. Section 63.3, “Config Watch” will also automatically detect changes and reload the application context.

63.1 How to activate

To get started with Consul Configuration use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-config. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.

This will enable auto-configuration that will setup Spring Cloud Consul Config.

63.2 Customizing

Consul Config may be customized using the following properties:

bootstrap.yml.  +

spring:
+  cloud:
+    consul:
+      config:
+        enabled: true
+        prefix: configuration
+        defaultContext: apps
+        profileSeparator: '::'

+

  • enabled setting this value to "false" disables Consul Config
  • prefix sets the base folder for configuration values
  • defaultContext sets the folder name used by all applications
  • profileSeparator sets the value of the separator used to separate the profile name in property sources with profiles

63.3 Config Watch

The Consul Config Watch takes advantage of the ability of consul to watch a key prefix. The Config Watch makes a blocking Consul HTTP API call to determine if any relevant configuration data has changed for the current application. If there is new configuration data a Refresh Event is published. This is equivalent to calling the /refresh actuator endpoint.

To change the frequency of when the Config Watch is called change spring.cloud.consul.config.watch.delay. The default value is 1000, which is in milliseconds.

To disable the Config Watch set spring.cloud.consul.config.watch.enabled=false.

63.4 YAML or Properties with Config

It may be more convenient to store a blob of properties in YAML or Properties format as opposed to individual key/value pairs. Set the spring.cloud.consul.config.format property to YAML or PROPERTIES. For example to use YAML:

bootstrap.yml.  +

spring:
+  cloud:
+    consul:
+      config:
+        format: YAML

+

YAML must be set in the appropriate data key in consul. Using the defaults above the keys would look like:

config/testApp,dev/data
+config/testApp/data
+config/application,dev/data
+config/application/data

You could store a YAML document in any of the keys listed above.

You can change the data key using spring.cloud.consul.config.data-key.

63.5 git2consul with Config

git2consul is a Consul community project that loads files from a git repository to individual keys into Consul. By default the names of the keys are names of the files. YAML and Properties files are supported with file extensions of .yml and .properties respectively. Set the spring.cloud.consul.config.format property to FILES. For example:

bootstrap.yml.  +

spring:
+  cloud:
+    consul:
+      config:
+        format: FILES

+

Given the following keys in /config, the development profile and an application name of foo:

.gitignore
+application.yml
+bar.properties
+foo-development.properties
+foo-production.yml
+foo.properties
+master.ref

the following property sources would be created:

config/foo-development.properties
+config/foo.properties
+config/application.yml

The value of each key needs to be a properly formatted YAML or Properties file.

63.6 Fail Fast

It may be convenient in certain circumstances (like local development or certain test scenarios) to not fail if consul isn’t available for configuration. Setting spring.cloud.consul.config.failFast=false in bootstrap.yml will cause the configuration module to log a warning rather than throw an exception. This will allow the application to continue startup normally.

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62. Service Discovery with Consul
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62. Service Discovery with Consul

Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Consul provides Service Discovery services via an HTTP API and DNS. Spring Cloud Consul leverages the HTTP API for service registration and discovery. This does not prevent non-Spring Cloud applications from leveraging the DNS interface. Consul Agents servers are run in a cluster that communicates via a gossip protocol and uses the Raft consensus protocol.

62.1 How to activate

To activate Consul Service Discovery use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-discovery. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.

62.2 Registering with Consul

When a client registers with Consul, it provides meta-data about itself such as host and port, id, name and tags. An HTTP Check is created by default that Consul hits the /health endpoint every 10 seconds. If the health check fails, the service instance is marked as critical.

Example Consul client:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello world";
+    }
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

(i.e. utterly normal Spring Boot app). If the Consul client is located somewhere other than localhost:8500, the configuration is required to locate the client. Example:

application.yml.  +

spring:
+  cloud:
+    consul:
+      host: localhost
+      port: 8500

+

[Caution]Caution

If you use Spring Cloud Consul Config, the above values will need to be placed in bootstrap.yml instead of application.yml.

The default service name, instance id and port, taken from the Environment, are ${spring.application.name}, the Spring Context ID and ${server.port} respectively.

To disable the Consul Discovery Client you can set spring.cloud.consul.discovery.enabled to false.

To disable the service registration you can set spring.cloud.consul.discovery.register to false.

62.3 HTTP Health Check

The health check for a Consul instance defaults to "/health", which is the default locations of a useful endpoint in a Spring Boot Actuator application. You need to change these, even for an Actuator application if you use a non-default context path or servlet path (e.g. server.servletPath=/foo) or management endpoint path (e.g. management.context-path=/admin). The interval that Consul uses to check the health endpoint may also be configured. "10s" and "1m" represent 10 seconds and 1 minute respectively. Example:

application.yml.  +

spring:
+  cloud:
+    consul:
+      discovery:
+        healthCheckPath: ${management.context-path}/health
+        healthCheckInterval: 15s

+

62.3.1 Metadata and Consul tags

Consul does not yet support metadata on services. Spring Cloud’s ServiceInstance has a Map<String, String> metadata field. Spring Cloud Consul uses Consul tags to approximate metadata until Consul officially supports metadata. Tags with the form key=value will be split and used as a Map key and value respectively. Tags without the equal = sign, will be used as both the key and value.

application.yml.  +

spring:
+  cloud:
+    consul:
+      discovery:
+        tags: foo=bar, baz

+

The above configuration will result in a map with foo→bar and baz→baz.

62.3.2 Making the Consul Instance ID Unique

By default a consul instance is registered with an ID that is equal to its Spring Application Context ID. By default, the Spring Application Context ID is ${spring.application.name}:comma,separated,profiles:${server.port}. For most cases, this will allow multiple instances of one service to run on one machine. If further uniqueness is required, Using Spring Cloud you can override this by providing a unique identifier in spring.cloud.consul.discovery.instanceId. For example:

application.yml.  +

spring:
+  cloud:
+    consul:
+      discovery:
+        instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}

+

With this metadata, and multiple service instances deployed on localhost, the random value will kick in there to make the instance unique. In Cloudfoundry the vcap.application.instance_id will be populated automatically in a Spring Boot application, so the random value will not be needed.

62.4 Looking up services

62.4.1 Using Ribbon

Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate +for looking up services using the logical service names/ids instead of physical URLs. Both Feign and the discovery-aware RestTemplate utilize Ribbon for client-side load balancing.

If you want to access service STORES using the RestTemplate simply declare:

@LoadBalanced
+@Bean
+public RestTemplate loadbalancedRestTemplate() {
+     new RestTemplate();
+}

and use it like this (notice how we use the STORES service name/id from Consul instead of a fully qualified domainname):

@Autowired
+RestTemplate restTemplate;
+
+public String getFirstProduct() {
+   return this.restTemplate.getForObject("https://STORES/products/1", String.class);
+}

If you have Consul clusters in multiple datacenters and you want to access a service in another datacenter a service name/id alone is not enough. In that case +you use property spring.cloud.consul.discovery.datacenters.STORES=dc-west where STORES is the service name/id and dc-west is the datacenter +where the STORES service lives.

62.4.2 Using the DiscoveryClient

You can also use the org.springframework.cloud.client.discovery.DiscoveryClient which provides a simple API for discovery clients that is not specific to Netflix, e.g.

@Autowired
+private DiscoveryClient discoveryClient;
+
+public String serviceUrl() {
+    List<ServiceInstance> list = discoveryClient.getInstances("STORES");
+    if (list != null && list.size() > 0 ) {
+        return list.get(0).getUri();
+    }
+    return null;
+}
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66. Circuit Breaker with Hystrix
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66. Circuit Breaker with Hystrix

Applications can use the Hystrix Circuit Breaker provided by the Spring Cloud Netflix project by including this starter in the projects pom.xml: spring-cloud-starter-hystrix. Hystrix doesn’t depend on the Netflix Discovery Client. The @EnableHystrix annotation should be placed on a configuration class (usually the main class). Then methods can be annotated with @HystrixCommand to be protected by a circuit breaker. See the documentation for more details.

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60. Install Consul
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60. Install Consul

Please see the installation documentation for instructions on how to install Consul.

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64. Consul Retry
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64. Consul Retry

If you expect that the consul agent may occasionally be unavailable when +your app starts, you can ask it to keep trying after a failure. You need to add +spring-retry and spring-boot-starter-aop to your classpath. The default +behaviour is to retry 6 times with an initial backoff interval of 1000ms and an +exponential multiplier of 1.1 for subsequent backoffs. You can configure these +properties (and others) using spring.cloud.consul.retry.* configuration properties. +This works with both Spring Cloud Consul Config and Discovery registration.

[Tip]Tip

To take full control of the retry add a @Bean of type +RetryOperationsInterceptor with id "consulRetryInterceptor". Spring +Retry has a RetryInterceptorBuilder that makes it easy to create one.

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67. Hystrix metrics aggregation with Turbine and Consul
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67. Hystrix metrics aggregation with Turbine and Consul

Turbine (provided by the Spring Cloud Netflix project), aggregates multiple instances Hystrix metrics streams, so the dashboard can display an aggregate view. Turbine uses the DiscoveryClient interface to lookup relevant instances. To use Turbine with Spring Cloud Consul, configure the Turbine application in a manner similar to the following examples:

pom.xml.  +

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-netflix-turbine</artifactId>
+</dependency>
+<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-starter-consul-discovery</artifactId>
+</dependency>

+

Notice that the Turbine dependency is not a starter. The turbine starter includes support for Netflix Eureka.

application.yml.  +

spring.application.name: turbine
+applications: consulhystrixclient
+turbine:
+  aggregator:
+    clusterConfig: ${applications}
+  appConfig: ${applications}

+

The clusterConfig and appConfig sections must match, so it’s useful to put the comma-separated list of service ID’s into a separate configuration property.

Turbine.java.  +

@EnableTurbine
+@SpringBootApplication
+public class Turbine {
+    public static void main(String[] args) {
+        SpringApplication.run(DemoturbinecommonsApplication.class, args);
+    }
+}

+

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12. Service Discovery: Eureka Server
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12. Service Discovery: Eureka Server

12.1 How to Include Eureka Server

To include Eureka Server in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-eureka-server. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

12.2 How to Run a Eureka Server

Example eureka server;

@SpringBootApplication
+@EnableEurekaServer
+public class Application {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

The server has a home page with a UI, and HTTP API endpoints per the +normal Eureka functionality under /eureka/*.

Eureka background reading: see flux capacitor and google group discussion.

[Tip]Tip

Due to Gradle’s dependency resolution rules and the lack of a parent bom feature, simply depending on spring-cloud-starter-netflix-eureka-server can cause failures on application startup. To remedy this the Spring Boot Gradle plugin must be added and the Spring cloud starter parent bom must be imported like so:

build.gradle.  +

buildscript {
+  dependencies {
+    classpath("org.springframework.boot:spring-boot-gradle-plugin:1.5.10.RELEASE")
+  }
+}
+
+apply plugin: "spring-boot"
+
+dependencyManagement {
+  imports {
+    mavenBom "org.springframework.cloud:spring-cloud-dependencies:Edgware.SR2"
+  }
+}

+

12.3 High Availability, Zones and Regions

The Eureka server does not have a backend store, but the service +instances in the registry all have to send heartbeats to keep their +registrations up to date (so this can be done in memory). Clients also +have an in-memory cache of eureka registrations (so they don’t have to +go to the registry for every single request to a service).

By default every Eureka server is also a Eureka client and requires +(at least one) service URL to locate a peer. If you don’t provide it +the service will run and work, but it will shower your logs with a lot +of noise about not being able to register with the peer.

See also below for details of Ribbon +support on the client side for Zones and Regions.

12.4 Standalone Mode

The combination of the two caches (client and server) and the +heartbeats make a standalone Eureka server fairly resilient to +failure, as long as there is some sort of monitor or elastic runtime +keeping it alive (e.g. Cloud Foundry). In standalone mode, you might +prefer to switch off the client side behaviour, so it doesn’t keep +trying and failing to reach its peers. Example:

application.yml (Standalone Eureka Server).  +

server:
+  port: 8761
+
+eureka:
+  instance:
+    hostname: localhost
+  client:
+    registerWithEureka: false
+    fetchRegistry: false
+    serviceUrl:
+      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

+

Notice that the serviceUrl is pointing to the same host as the local +instance.

12.5 Peer Awareness

Eureka can be made even more resilient and available by running +multiple instances and asking them to register with each other. In +fact, this is the default behaviour, so all you need to do to make it +work is add a valid serviceUrl to a peer, e.g.

application.yml (Two Peer Aware Eureka Servers).  +

---
+spring:
+  profiles: peer1
+eureka:
+  instance:
+    hostname: peer1
+  client:
+    serviceUrl:
+      defaultZone: http://peer2/eureka/
+
+---
+spring:
+  profiles: peer2
+eureka:
+  instance:
+    hostname: peer2
+  client:
+    serviceUrl:
+      defaultZone: http://peer1/eureka/

+

In this example we have a YAML file that can be used to run the same +server on 2 hosts (peer1 and peer2), by running it in different +Spring profiles. You could use this configuration to test the peer +awareness on a single host (there’s not much value in doing that in +production) by manipulating /etc/hosts to resolve the host names. In +fact, the eureka.instance.hostname is not needed if you are running +on a machine that knows its own hostname (it is looked up using +java.net.InetAddress by default).

You can add multiple peers to a system, and as long as they are all +directly connected to each other, they will synchronize +the registrations amongst themselves.

application.yml (Three Peer Aware Eureka Servers).  +

eureka:
+  client:
+    serviceUrl:
+      defaultZone: http://peer1/eureka/,http://peer2/eureka/,http://peer3/eureka/
+
+---
+spring:
+  profiles: peer1
+eureka:
+  instance:
+    hostname: peer1
+
+---
+spring:
+  profiles: peer2
+eureka:
+  instance:
+    hostname: peer2
+
+---
+spring:
+  profiles: peer3
+eureka:
+  instance:
+    hostname: peer3

+

12.6 Prefer IP Address

In some cases, it is preferable for Eureka to advertise the IP Adresses +of services rather than the hostname. Set eureka.instance.preferIpAddress +to true and when the application registers with eureka, it will use its +IP Address rather than its hostname.

[Tip]Tip

If hostname can’t be determined by Java, then IP address is sent to Eureka. +Only explict way of setting hostname is by using eureka.instance.hostname. +You can set your hostname at the run time using environment variable, for +example eureka.instance.hostname=${HOST_NAME}.

Prev Up Next
11. Service Discovery: Eureka Clients Home 13. Circuit Breaker: Hystrix Clients
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17. Declarative REST Client: Feign
Prev Part III. Spring Cloud Netflix Next

17. Declarative REST Client: Feign

Feign is a declarative web service client. It makes writing web service clients easier. To use Feign create an interface and annotate it. It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders. Spring Cloud adds support for Spring MVC annotations and for using the same HttpMessageConverters used by default in Spring Web. Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign.

17.1 How to Include Feign

To include Feign in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-openfeign. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

Example spring boot app

@Configuration
+@ComponentScan
+@EnableAutoConfiguration
+@EnableFeignClients
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}

StoreClient.java.  +

@FeignClient("stores")
+public interface StoreClient {
+    @RequestMapping(method = RequestMethod.GET, value = "/stores")
+    List<Store> getStores();
+
+    @RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
+    Store update(@PathVariable("storeId") Long storeId, Store store);
+}

+

In the @FeignClient annotation the String value ("stores" above) is +an arbitrary client name, which is used to create a Ribbon load +balancer (see below for details of Ribbon +support). You can also specify a URL using the url attribute +(absolute value or just a hostname). The name of the bean in the +application context is the fully qualified name of the interface. +To specify your own alias value you can use the qualifier value +of the @FeignClient annotation.

The Ribbon client above will want to discover the physical addresses +for the "stores" service. If your application is a Eureka client then +it will resolve the service in the Eureka service registry. If you +don’t want to use Eureka, you can simply configure a list of servers +in your external configuration (see +above for example).

17.2 Overriding Feign Defaults

A central concept in Spring Cloud’s Feign support is that of the named client. Each feign client is part of an ensemble of components that work together to contact a remote server on demand, and the ensemble has a name that you give it as an application developer using the @FeignClient annotation. Spring Cloud creates a new ensemble as an +ApplicationContext on demand for each named client using FeignClientsConfiguration. This contains (amongst other things) an feign.Decoder, a feign.Encoder, and a feign.Contract.

Spring Cloud lets you take full control of the feign client by declaring additional configuration (on top of the FeignClientsConfiguration) using @FeignClient. Example:

@FeignClient(name = "stores", configuration = FooConfiguration.class)
+public interface StoreClient {
+    //..
+}

In this case the client is composed from the components already in FeignClientsConfiguration together with any in FooConfiguration (where the latter will override the former).

[Note]Note

FooConfiguration does not need to be annotated with @Configuration. However, if it is, then take care to exclude it from any @ComponentScan that would otherwise include this configuration as it will become the default source for feign.Decoder, feign.Encoder, feign.Contract, etc., when specified. This can be avoided by putting it in a separate, non-overlapping package from any @ComponentScan or @SpringBootApplication, or it can be explicitly excluded in @ComponentScan.

[Note]Note

The serviceId attribute is now deprecated in favor of the name attribute.

[Warning]Warning

Previously, using the url attribute, did not require the name attribute. Using name is now required.

Placeholders are supported in the name and url attributes.

@FeignClient(name = "${feign.name}", url = "${feign.url}")
+public interface StoreClient {
+    //..
+}

Spring Cloud Netflix provides the following beans by default for feign (BeanType beanName: ClassName):

  • Decoder feignDecoder: ResponseEntityDecoder (which wraps a SpringDecoder)
  • Encoder feignEncoder: SpringEncoder
  • Logger feignLogger: Slf4jLogger
  • Contract feignContract: SpringMvcContract
  • Feign.Builder feignBuilder: HystrixFeign.Builder
  • Client feignClient: if Ribbon is enabled it is a LoadBalancerFeignClient, otherwise the default feign client is used.

The OkHttpClient and ApacheHttpClient feign clients can be used by setting feign.okhttp.enabled or feign.httpclient.enabled to true, respectively, and having them on the classpath. +You can customize the HTTP client used by providing a bean of either ClosableHttpClient when using Apache or OkHttpClient whe using OK HTTP.

Spring Cloud Netflix does not provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client:

  • Logger.Level
  • Retryer
  • ErrorDecoder
  • Request.Options
  • Collection<RequestInterceptor>
  • SetterFactory

Creating a bean of one of those type and placing it in a @FeignClient configuration (such as FooConfiguration above) allows you to override each one of the beans described. Example:

@Configuration
+public class FooConfiguration {
+    @Bean
+    public Contract feignContract() {
+        return new feign.Contract.Default();
+    }
+
+    @Bean
+    public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
+        return new BasicAuthRequestInterceptor("user", "password");
+    }
+}

This replaces the SpringMvcContract with feign.Contract.Default and adds a RequestInterceptor to the collection of RequestInterceptor.

@FeignClient also can be configured using configuration properties.

application.yml

feign:
+  client:
+    config:
+      feignName:
+        connectTimeout: 5000
+        readTimeout: 5000
+        loggerLevel: full
+        errorDecoder: com.example.SimpleErrorDecoder
+        retryer: com.example.SimpleRetryer
+        requestInterceptors:
+          - com.example.FooRequestInterceptor
+          - com.example.BarRequestInterceptor
+        decode404: false

Default configurations can be specified in the @EnableFeignClients attribute defaultConfiguration in a similar manner as described above. The difference is that this configuration will apply to all feign clients.

If you prefer using configuration properties to configured all @FeignClient, you can create configuration properties with default feign name.

application.yml

feign:
+  client:
+    config:
+      default:
+        connectTimeout: 5000
+        readTimeout: 5000
+        loggerLevel: basic

If we create both @Configuration bean and configuration properties, configuration properties will win. +It will override @Configuration values. But if you want to change the priority to @Configuration, +you can change feign.client.default-to-properties to false.

[Note]Note

If you need to use ThreadLocal bound variables in your RequestInterceptor`s you will need to either set the +thread isolation strategy for Hystrix to `SEMAPHORE or disable Hystrix in Feign.

application.yml

# To disable Hystrix in Feign
+feign:
+  hystrix:
+    enabled: false
+
+# To set thread isolation to SEMAPHORE
+hystrix:
+  command:
+    default:
+      execution:
+        isolation:
+          strategy: SEMAPHORE

17.3 Creating Feign Clients Manually

In some cases it might be necessary to customize your Feign Clients in a way that is not +possible using the methods above. In this case you can create Clients using the +Feign Builder API. Below is an example +which creates two Feign Clients with the same interface but configures each one with +a separate request interceptor.

@Import(FeignClientsConfiguration.class)
+class FooController {
+
+	private FooClient fooClient;
+
+	private FooClient adminClient;
+
+    	@Autowired
+	public FooController(
+			Decoder decoder, Encoder encoder, Client client) {
+		this.fooClient = Feign.builder().client(client)
+				.encoder(encoder)
+				.decoder(decoder)
+				.requestInterceptor(new BasicAuthRequestInterceptor("user", "user"))
+				.target(FooClient.class, "http://PROD-SVC");
+		this.adminClient = Feign.builder().client(client)
+				.encoder(encoder)
+				.decoder(decoder)
+				.requestInterceptor(new BasicAuthRequestInterceptor("admin", "admin"))
+				.target(FooClient.class, "http://PROD-SVC");
+    }
+}
[Note]Note

In the above example FeignClientsConfiguration.class is the default configuration +provided by Spring Cloud Netflix.

[Note]Note

PROD-SVC is the name of the service the Clients will be making requests to.

17.4 Feign Hystrix Support

If Hystrix is on the classpath and feign.hystrix.enabled=true, Feign will wrap all methods with a circuit breaker. Returning a com.netflix.hystrix.HystrixCommand is also available. This lets you use reactive patterns (with a call to .toObservable() or .observe() or asynchronous use (with a call to .queue()).

To disable Hystrix support on a per-client basis create a vanilla Feign.Builder with the "prototype" scope, e.g.:

@Configuration
+public class FooConfiguration {
+    	@Bean
+	@Scope("prototype")
+	public Feign.Builder feignBuilder() {
+		return Feign.builder();
+	}
+}
[Warning]Warning

Prior to the Spring Cloud Dalston release, if Hystrix was on the classpath Feign would have wrapped +all methods in a circuit breaker by default. This default behavior was changed in Spring Cloud Dalston in +favor for an opt-in approach.

17.5 Feign Hystrix Fallbacks

Hystrix supports the notion of a fallback: a default code path that is executed when they circuit is open or there is an error. To enable fallbacks for a given @FeignClient set the fallback attribute to the class name that implements the fallback. You also need to declare your implementation as a Spring bean.

@FeignClient(name = "hello", fallback = HystrixClientFallback.class)
+protected interface HystrixClient {
+    @RequestMapping(method = RequestMethod.GET, value = "/hello")
+    Hello iFailSometimes();
+}
+
+static class HystrixClientFallback implements HystrixClient {
+    @Override
+    public Hello iFailSometimes() {
+        return new Hello("fallback");
+    }
+}

If one needs access to the cause that made the fallback trigger, one can use the fallbackFactory attribute inside @FeignClient.

@FeignClient(name = "hello", fallbackFactory = HystrixClientFallbackFactory.class)
+protected interface HystrixClient {
+	@RequestMapping(method = RequestMethod.GET, value = "/hello")
+	Hello iFailSometimes();
+}
+
+@Component
+static class HystrixClientFallbackFactory implements FallbackFactory<HystrixClient> {
+	@Override
+	public HystrixClient create(Throwable cause) {
+		return new HystrixClient() {
+			@Override
+			public Hello iFailSometimes() {
+				return new Hello("fallback; reason was: " + cause.getMessage());
+			}
+		};
+	}
+}
[Warning]Warning

There is a limitation with the implementation of fallbacks in Feign and how Hystrix fallbacks work. Fallbacks are currently not supported for methods that return com.netflix.hystrix.HystrixCommand and rx.Observable.

17.6 Feign and @Primary

When using Feign with Hystrix fallbacks, there are multiple beans in the ApplicationContext of the same type. This will cause @Autowired to not work because there isn’t exactly one bean, or one marked as primary. To work around this, Spring Cloud Netflix marks all Feign instances as @Primary, so Spring Framework will know which bean to inject. In some cases, this may not be desirable. To turn off this behavior set the primary attribute of @FeignClient to false.

@FeignClient(name = "hello", primary = false)
+public interface HelloClient {
+	// methods here
+}

17.7 Feign Inheritance Support

Feign supports boilerplate apis via single-inheritance interfaces. +This allows grouping common operations into convenient base interfaces.

UserService.java.  +

public interface UserService {
+
+    @RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
+    User getUser(@PathVariable("id") long id);
+}

+

UserResource.java.  +

@RestController
+public class UserResource implements UserService {
+
+}

+

UserClient.java.  +

package project.user;
+
+@FeignClient("users")
+public interface UserClient extends UserService {
+
+}

+

[Note]Note

It is generally not advisable to share an interface between a +server and a client. It introduces tight coupling, and also actually +doesn’t work with Spring MVC in its current form (method parameter +mapping is not inherited).

17.8 Feign request/response compression

You may consider enabling the request or response GZIP compression for your +Feign requests. You can do this by enabling one of the properties:

feign.compression.request.enabled=true
+feign.compression.response.enabled=true

Feign request compression gives you settings similar to what you may set for your web server:

feign.compression.request.enabled=true
+feign.compression.request.mime-types=text/xml,application/xml,application/json
+feign.compression.request.min-request-size=2048

These properties allow you to be selective about the compressed media types and minimum request threshold length.

17.9 Feign logging

A logger is created for each Feign client created. By default the name of the logger is the full class name of the interface used to create the Feign client. Feign logging only responds to the DEBUG level.

application.yml.  +

logging.level.project.user.UserClient: DEBUG

+

The Logger.Level object that you may configure per client, tells Feign how much to log. Choices are:

  • NONE, No logging (DEFAULT).
  • BASIC, Log only the request method and URL and the response status code and execution time.
  • HEADERS, Log the basic information along with request and response headers.
  • FULL, Log the headers, body, and metadata for both requests and responses.

For example, the following would set the Logger.Level to FULL:

@Configuration
+public class FooConfiguration {
+    @Bean
+    Logger.Level feignLoggerLevel() {
+        return Logger.Level.FULL;
+    }
+}
Prev Up Next
16. Client Side Load Balancer: Ribbon Home 18. External Configuration: Archaius
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16. Client Side Load Balancer: Ribbon
Prev Part III. Spring Cloud Netflix Next

16. Client Side Load Balancer: Ribbon

Ribbon is a client side load balancer which gives you a lot of control +over the behaviour of HTTP and TCP clients. Feign already uses Ribbon, +so if you are using @FeignClient then this section also applies.

A central concept in Ribbon is that of the named client. Each load +balancer is part of an ensemble of components that work together to +contact a remote server on demand, and the ensemble has a name that +you give it as an application developer (e.g. using the @FeignClient +annotation). Spring Cloud creates a new ensemble as an +ApplicationContext on demand for each named client using +RibbonClientConfiguration. This contains (amongst other things) an +ILoadBalancer, a RestClient, and a ServerListFilter.

16.1 How to Include Ribbon

To include Ribbon in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-ribbon. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

16.2 Customizing the Ribbon Client

You can configure some bits of a Ribbon client using external +properties in <client>.ribbon.*, which is no different than using +the Netflix APIs natively, except that you can use Spring Boot +configuration files. The native options can +be inspected as static fields in CommonClientConfigKey (part of +ribbon-core).

Spring Cloud also lets you take full control of the client by +declaring additional configuration (on top of the +RibbonClientConfiguration) using @RibbonClient. Example:

@Configuration
+@RibbonClient(name = "foo", configuration = FooConfiguration.class)
+public class TestConfiguration {
+}

In this case the client is composed from the components already in +RibbonClientConfiguration together with any in FooConfiguration +(where the latter generally will override the former).

[Warning]Warning

The FooConfiguration has to be @Configuration but take +care that it is not in a @ComponentScan for the main application +context, otherwise it will be shared by all the @RibbonClients. If +you use @ComponentScan (or @SpringBootApplication) you need to +take steps to avoid it being included (for instance put it in a +separate, non-overlapping package, or specify the packages to scan +explicitly in the @ComponentScan).

Spring Cloud Netflix provides the following beans by default for ribbon +(BeanType beanName: ClassName):

  • IClientConfig ribbonClientConfig: DefaultClientConfigImpl
  • IRule ribbonRule: ZoneAvoidanceRule
  • IPing ribbonPing: DummyPing
  • ServerList<Server> ribbonServerList: ConfigurationBasedServerList
  • ServerListFilter<Server> ribbonServerListFilter: ZonePreferenceServerListFilter
  • ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
  • ServerListUpdater ribbonServerListUpdater: PollingServerListUpdater

Creating a bean of one of those type and placing it in a @RibbonClient +configuration (such as FooConfiguration above) allows you to override each +one of the beans described. Example:

@Configuration
+protected static class FooConfiguration {
+	@Bean
+	public ZonePreferenceServerListFilter serverListFilter() {
+		ZonePreferenceServerListFilter filter = new ZonePreferenceServerListFilter();
+		filter.setZone("myTestZone");
+		return filter;
+	}
+
+	@Bean
+	public IPing ribbonPing() {
+		return new PingUrl();
+	}
+}

This replaces the NoOpPing with PingUrl and provides a custom serverListFilter

16.3 Customizing default for all Ribbon Clients

A default configuration can be provided for all Ribbon Clients using the @RibbonClients annotation and registering a default configuration as shown in the following example:

@RibbonClients(defaultConfiguration = DefaultRibbonConfig.class)
+public class RibbonClientDefaultConfigurationTestsConfig {
+
+	public static class BazServiceList extends ConfigurationBasedServerList {
+		public BazServiceList(IClientConfig config) {
+			super.initWithNiwsConfig(config);
+		}
+	}
+}
+
+@Configuration
+class DefaultRibbonConfig {
+
+	@Bean
+	public IRule ribbonRule() {
+		return new BestAvailableRule();
+	}
+
+	@Bean
+	public IPing ribbonPing() {
+		return new PingUrl();
+	}
+
+	@Bean
+	public ServerList<Server> ribbonServerList(IClientConfig config) {
+		return new RibbonClientDefaultConfigurationTestsConfig.BazServiceList(config);
+	}
+
+	@Bean
+	public ServerListSubsetFilter serverListFilter() {
+		ServerListSubsetFilter filter = new ServerListSubsetFilter();
+		return filter;
+	}
+
+}

16.4 Customizing the Ribbon Client using properties

Starting with version 1.2.0, Spring Cloud Netflix now supports customizing Ribbon clients using properties to be compatible with the Ribbon documentation.

This allows you to change behavior at start up time in different environments.

The supported properties are listed below and should be prefixed by <clientName>.ribbon.:

  • NFLoadBalancerClassName: should implement ILoadBalancer
  • NFLoadBalancerRuleClassName: should implement IRule
  • NFLoadBalancerPingClassName: should implement IPing
  • NIWSServerListClassName: should implement ServerList
  • NIWSServerListFilterClassName should implement ServerListFilter
[Note]Note

Classes defined in these properties have precedence over beans defined using @RibbonClient(configuration=MyRibbonConfig.class) and the defaults provided by Spring Cloud Netflix.

To set the IRule for a service name users you could set the following:

application.yml.  +

users:
+  ribbon:
+    NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList
+    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.WeightedResponseTimeRule

+

See the Ribbon documentation for implementations provided by Ribbon.

16.5 Using Ribbon with Eureka

When Eureka is used in conjunction with Ribbon (i.e., both are on the classpath) the ribbonServerList +is overridden with an extension of DiscoveryEnabledNIWSServerList +which populates the list of servers from Eureka. It also replaces the +IPing interface with NIWSDiscoveryPing which delegates to Eureka +to determine if a server is up. The ServerList that is installed by +default is a DomainExtractingServerList and the purpose of this is +to make physical metadata available to the load balancer without using +AWS AMI metadata (which is what Netflix relies on). By default the +server list will be constructed with "zone" information as provided in +the instance metadata (so on the remote clients set +eureka.instance.metadataMap.zone), and if that is missing it can use +the domain name from the server hostname as a proxy for zone (if the +flag approximateZoneFromHostname is set). Once the zone information +is available it can be used in a ServerListFilter. By default it +will be used to locate a server in the same zone as the client because +the default is a ZonePreferenceServerListFilter. The zone of the +client is determined the same way as the remote instances by default, +i.e. via eureka.instance.metadataMap.zone.

[Note]Note

The orthodox "archaius" way to set the client zone is via a +configuration property called "@zone", and Spring Cloud will use that +in preference to all other settings if it is available (note that the +key will have to be quoted in YAML configuration).

[Note]Note

If there is no other source of zone data then a guess is made +based on the client configuration (as opposed to the instance +configuration). We take eureka.client.availabilityZones, which is a +map from region name to a list of zones, and pull out the first zone +for the instance’s own region (i.e. the eureka.client.region, which +defaults to "us-east-1" for comatibility with native Netflix).

16.6 Example: How to Use Ribbon Without Eureka

Eureka is a convenient way to abstract the discovery of remote servers +so you don’t have to hard code their URLs in clients, but if you +prefer not to use it, Ribbon and Feign are still quite +amenable. Suppose you have declared a @RibbonClient for "stores", +and Eureka is not in use (and not even on the classpath). The Ribbon +client defaults to a configured server list, and you can supply the +configuration like this

application.yml.  +

stores:
+  ribbon:
+    listOfServers: example.com,google.com

+

16.7 Example: Disable Eureka use in Ribbon

Setting the property ribbon.eureka.enabled = false will explicitly +disable the use of Eureka in Ribbon.

application.yml.  +

ribbon:
+  eureka:
+   enabled: false

+

16.8 Using the Ribbon API Directly

You can also use the LoadBalancerClient directly. Example:

public class MyClass {
+    @Autowired
+    private LoadBalancerClient loadBalancer;
+
+    public void doStuff() {
+        ServiceInstance instance = loadBalancer.choose("stores");
+        URI storesUri = URI.create(String.format("http://%s:%s", instance.getHost(), instance.getPort()));
+        // ... do something with the URI
+    }
+}

16.9 Caching of Ribbon Configuration

Each Ribbon named client has a corresponding child Application Context that Spring Cloud maintains, this application context is lazily loaded up on the first request to the named client. +This lazy loading behavior can be changed to instead eagerly load up these child Application contexts at startup by specifying the names of the Ribbon clients.

application.yml.  +

ribbon:
+  eager-load:
+    enabled: true
+    clients: client1, client2, client3

+

16.10 How to Configure Hystrix thread pools

If you change zuul.ribbonIsolationStrategy to THREAD, the thread isolation strategy for Hystrix will be used for all routes. In this case, the HystrixThreadPoolKey is set to "RibbonCommand" as default. It means that HystrixCommands for all routes will be executed in the same Hystrix thread pool. This behavior can be changed using the following configuration and it will result in HystrixCommands being executed in the Hystrix thread pool for each route.

application.yml.  +

zuul:
+  threadPool:
+    useSeparateThreadPools: true

+

The default HystrixThreadPoolKey in this case is same with service ID for each route. To add a prefix to HystrixThreadPoolKey, set zuul.threadPool.threadPoolKeyPrefix to a value that you want to add. For example:

application.yml.  +

zuul:
+  threadPool:
+    useSeparateThreadPools: true
+    threadPoolKeyPrefix: zuulgw

+

16.11 How to Provide a Key to Ribbon’s IRule

If you need to provide your own IRule implementation to handle a special routing requirement like a canary test, +you probably want to pass some information to the choose method of IRule.

com.netflix.loadbalancer.IRule.java.  +

public interface IRule{
+    public Server choose(Object key);
+         :

+

You can provide some information that will be used to choose a target server by your IRule implementation like +the following:

RequestContext.getCurrentContext()
+              .set(FilterConstants.LOAD_BALANCER_KEY, "canary-test");

If you put any object into the RequestContext with a key FilterConstants.LOAD_BALANCER_KEY, it will +be passed to the choose method of IRule implementation. Above code must be executed before RibbonRoutingFilter +is executed and Zuul’s pre filter is the best place to do that. You can easily access HTTP headers and query parameters +via RequestContext in pre filter, so it can be used to determine LOAD_BALANCER_KEY that will be passed to Ribbon. +If you don’t put any value with LOAD_BALANCER_KEY in RequestContext, null will be passed as a parameter of choose +method.

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74. Distributed Configuration with Zookeeper
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74. Distributed Configuration with Zookeeper

Zookeeper provides a hierarchical namespace that allows clients to store arbitrary data, such as configuration data. Spring Cloud Zookeeper Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config namespace by default. Multiple PropertySource instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created:

config/testApp,dev
+config/testApp
+config/application,dev
+config/application

The most specific property source is at the top, with the least specific at the bottom. Properties is the config/application namespace are applicable to all applications using zookeeper for configuration. Properties in the config/testApp namespace are only available to the instances of the service named "testApp".

Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh will cause the configuration to be reloaded. Watching the configuration namespace (which Zookeeper supports) is not currently implemented, but will be a future addition to this project.

74.1 How to activate

Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-config will enable auto-configuration that will setup Spring Cloud Zookeeper Config.

74.2 Customizing

Zookeeper Config may be customized using the following properties:

bootstrap.yml.  +

spring:
+  cloud:
+    zookeeper:
+      config:
+        enabled: true
+        root: configuration
+        defaultContext: apps
+        profileSeparator: '::'

+

  • enabled setting this value to "false" disables Zookeeper Config
  • root sets the base namespace for configuration values
  • defaultContext sets the name used by all applications
  • profileSeparator sets the value of the separator used to separate the profile name in property sources with profiles

74.3 ACLs

You can add authentication information for Zookeeper ACLs by calling the addAuthInfo method of a +CuratorFramework bean. One way to accomplish this is by providing your own CuratorFramework bean:

@BoostrapConfiguration
+public class CustomCuratorFrameworkConfig {
+
+  @Bean
+  public CuratorFramework curatorFramework() {
+    CuratorFramework curator = new CuratorFramework();
+    curator.addAuthInfo("digest", "user:password".getBytes());
+    return curator;
+  }
+
+}

Consult the ZookeeperAutoConfiguration class +to see how the CuratorFramework bean is configured by default.

Alternatively, you can add your credentials from a class that depends on the existing +CuratorFramework bean:

@BoostrapConfiguration
+public class DefaultCuratorFrameworkConfig {
+
+  public ZookeeperConfig(CuratorFramework curator) {
+    curator.addAuthInfo("digest", "user:password".getBytes());
+  }
+
+}

This must occur during the boostrapping phase. You can register configuration classes to run +during this phase by annotating them with @BootstrapConfiguration and including them in a +comma-separated list set as the value of the property +org.springframework.cloud.bootstrap.BootstrapConfiguration in the file +resources/META-INF/spring.factories:

resources/META-INF/spring.factories.  +

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
+my.project.CustomCuratorFrameworkConfig,\
+my.project.DefaultCuratorFrameworkConfig

+

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73. Spring Cloud Zookeeper Dependency Watcher Home Part X. Spring Boot Cloud CLI
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72. Zookeeper Dependencies
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72. Zookeeper Dependencies

72.1 Using the Zookeeper Dependencies

Spring Cloud Zookeeper gives you a possibility to provide dependencies of your application as properties. As dependencies you can understand other applications that are registered +in Zookeeper and which you would like to call via Feign (a REST client builder) +and also Spring RestTemplate.

You can also benefit from the Zookeeper Dependency Watchers functionality that lets you control and monitor what is the state of your dependencies and decide what to do with that.

72.2 How to activate Zookeeper Dependencies

  • Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery will enable auto-configuration that will setup Spring Cloud Zookeeper Dependencies.
  • If you have to have the spring.cloud.zookeeper.dependencies section properly set up - check the subsequent section for more details then the feature is active
  • You can have the dependencies turned off even if you’ve provided the dependencies in your properties. Just set the property spring.cloud.zookeeper.dependency.enabled to false (defaults to true).

72.3 Setting up Zookeeper Dependencies

Let’s take a closer look at an example of dependencies representation:

application.yml.  +

spring.application.name: yourServiceName
+spring.cloud.zookeeper:
+  dependencies:
+    newsletter:
+      path: /path/where/newsletter/has/registered/in/zookeeper
+      loadBalancerType: ROUND_ROBIN
+      contentTypeTemplate: application/vnd.newsletter.$version+json
+      version: v1
+      headers:
+        header1:
+            - value1
+        header2:
+            - value2
+      required: false
+      stubs: org.springframework:foo:stubs
+    mailing:
+      path: /path/where/mailing/has/registered/in/zookeeper
+      loadBalancerType: ROUND_ROBIN
+      contentTypeTemplate: application/vnd.mailing.$version+json
+      version: v1
+      required: true

+

Let’s now go through each part of the dependency one by one. The root property name is spring.cloud.zookeeper.dependencies.

72.3.1 Aliases

Below the root property you have to represent each dependency has by an alias due to the constraints of Ribbon (the application id has to be placed in the URL +thus you can’t pass any complex path like /foo/bar/name). The alias will be the name that you will use instead of serviceId for DiscoveryClient, Feign or RestTemplate.

In the aforementioned examples the aliases are newsletter and mailing. Example of Feign usage with newsletter would be:

@FeignClient("newsletter")
+public interface NewsletterService {
+        @RequestMapping(method = RequestMethod.GET, value = "/newsletter")
+        String getNewsletters();
+}

72.3.2 Path

Represented by path yaml property.

Path is the path under which the dependency is registered under Zookeeper. Like presented before Ribbon operates on URLs thus this path is not compliant with its requirement. +That is why Spring Cloud Zookeeper maps the alias to the proper path.

72.3.3 Load balancer type

Represented by loadBalancerType yaml property.

If you know what kind of load balancing strategy has to be applied when calling this particular dependency then you can provide it in the yaml file and it will be automatically applied. +You can choose one of the following load balancing strategies

  • STICKY - once chosen the instance will always be called
  • RANDOM - picks an instance randomly
  • ROUND_ROBIN - iterates over instances over and over again

72.3.4 Content-Type template and version

Represented by contentTypeTemplate and version yaml property.

If you version your api via the Content-Type header then you don’t want to add this header to each of your requests. Also if you want to call a new version of the API you don’t want to +roam around your code to bump up the API version. That’s why you can provide a contentTypeTemplate with a special $version placeholder. That placeholder will be filled by the value of the +version yaml property. Let’s take a look at an example.

Having the following contentTypeTemplate:

application/vnd.newsletter.$version+json

and the following version:

v1

Will result in setting up of a Content-Type header for each request:

application/vnd.newsletter.v1+json

72.3.5 Default headers

Represented by headers map in yaml

Sometimes each call to a dependency requires setting up of some default headers. In order not to do that in code you can set them up in the yaml file. +Having the following headers section:

headers:
+    Accept:
+        - text/html
+        - application/xhtml+xml
+    Cache-Control:
+        - no-cache

Results in adding the Accept and Cache-Control headers with appropriate list of values in your HTTP request.

72.3.6 Obligatory dependencies

Represented by required property in yaml

If one of your dependencies is required to be up and running when your application is booting then it’s enough to set up the required: true property in the yaml file.

If your application can’t localize the required dependency during boot time it will throw an exception and the Spring Context will fail to set up. +In other words your application won’t be able to start if the required dependency is not registered in Zookeeper.

You can read more about Spring Cloud Zookeeper Presence Checker in the following sections.

72.3.7 Stubs

You can provide a colon separated path to the JAR containing stubs of the dependency. Example

stubs: org.springframework:foo:stubs

means that for a particular dependencies can be found under:

  • groupId: org.springframework
  • artifactId: foo
  • classifier: stubs - this is the default value

This is actually equal to

stubs: org.springframework:foo

since stubs is the default classifier.

72.4 Configuring Spring Cloud Zookeeper Dependencies

There is a bunch of properties that you can set to enable / disable parts of Zookeeper Dependencies functionalities.

  • spring.cloud.zookeeper.dependencies - if you don’t set this property you won’t benefit from Zookeeper Dependencies
  • spring.cloud.zookeeper.dependency.ribbon.enabled (enabled by default) - Ribbon requires explicit global configuration or a particular one for a dependency. By turning on this property +runtime load balancing strategy resolution is possible and you can profit from the loadBalancerType section of the Zookeeper Dependencies. The configuration that needs this property +has an implementation of LoadBalancerClient that delegates to the ILoadBalancer presented in the next bullet
  • spring.cloud.zookeeper.dependency.ribbon.loadbalancer (enabled by default) - thanks to this property the custom ILoadBalancer knows that the part of the URI passed to Ribbon might +actually be the alias that has to be resolved to a proper path in Zookeeper. Without this property you won’t be able to register applications under nested paths.
  • spring.cloud.zookeeper.dependency.headers.enabled (enabled by default) - this property registers such a RibbonClient that automatically will append appropriate headers and content +types with version as presented in the Dependency configuration. Without this setting of those two parameters will not be operational.
  • spring.cloud.zookeeper.dependency.resttemplate.enabled (enabled by default) - when enabled will modify the request headers of @LoadBalanced annotated RestTemplate so that it passes +headers and content type with version set in Dependency configuration. Wihtout this setting of those two parameters will not be operational.
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71. Spring Cloud Zookeeper and Service Registry Home 73. Spring Cloud Zookeeper Dependency Watcher
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73. Spring Cloud Zookeeper Dependency Watcher
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73. Spring Cloud Zookeeper Dependency Watcher

The Dependency Watcher mechanism allows you to register listeners to your dependencies. The functionality is in fact an implementation of the Observator pattern. When a dependency changes +its state (UP or DOWN) then some custom logic can be applied.

73.1 How to activate

Spring Cloud Zookeeper Dependencies functionality needs to be enabled to profit from Dependency Watcher mechanism.

73.2 Registering a listener

In order to register a listener you have to implement an interface org.springframework.cloud.zookeeper.discovery.watcher.DependencyWatcherListener and register it as a bean. +The interface gives you one method:

    void stateChanged(String dependencyName, DependencyState newState);

If you want to register a listener for a particular dependency then the dependencyName would be the discriminator for your concrete implementation. newState will provide you with information + whether your dependency has changed to CONNECTED or DISCONNECTED.

73.3 Presence Checker

Bound with Dependency Watcher is the functionality called Presence Checker. It allows you to provide custom behaviour upon booting of your application to react accordingly to the state +of your dependencies.

The default implementation of the abstract org.springframework.cloud.zookeeper.discovery.watcher.presence.DependencyPresenceOnStartupVerifier class is the +org.springframework.cloud.zookeeper.discovery.watcher.presence.DefaultDependencyPresenceOnStartupVerifier which works in the following way.

  • If the dependency is marked us required and it’s not in Zookeeper then upon booting your application will throw an exception and shutdown
  • If dependency is not required the org.springframework.cloud.zookeeper.discovery.watcher.presence.LogMissingDependencyChecker will log that application is missing at WARN level

The functionality can be overriden since the DefaultDependencyPresenceOnStartupVerifier is registered only when there is no bean of DependencyPresenceOnStartupVerifier.

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72. Zookeeper Dependencies Home 74. Distributed Configuration with Zookeeper
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69. Service Discovery with Zookeeper
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69. Service Discovery with Zookeeper

Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Curator(A java library for Zookeeper) provides Service Discovery services via Service Discovery Extension. Spring Cloud Zookeeper leverages this extension for service registration and discovery.

69.1 How to activate

Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery will enable auto-configuration that will setup Spring Cloud Zookeeper Discovery.

[Note]Note

You still need to include org.springframework.boot:spring-boot-starter-web for web functionality.

69.2 Registering with Zookeeper

When a client registers with Zookeeper, it provides meta-data about itself such as host and port, id and name.

Example Zookeeper client:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello world";
+    }
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

(i.e. utterly normal Spring Boot app). If Zookeeper is located somewhere other than localhost:2181, the configuration is required to locate the server. Example:

application.yml.  +

spring:
+  cloud:
+    zookeeper:
+      connect-string: localhost:2181

+

[Caution]Caution

If you use Spring Cloud Zookeeper Config, the above values will need to be placed in bootstrap.yml instead of application.yml.

The default service name, instance id and port, taken from the Environment, are ${spring.application.name}, the Spring Context ID and ${server.port} respectively.

Having spring-cloud-starter-zookeeper-discovery on the classpath makes the app into both a Zookeeper "service" (i.e. it registers itself) and a "client" (i.e. it can query Zookeeper to locate other services).

If you would like to disable the Zookeeper Discovery Client you can set spring.cloud.zookeeper.discovery.enabled to false.

69.3 Using the DiscoveryClient

Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate using the logical service names instead of physical URLs.

You can also use the org.springframework.cloud.client.discovery.DiscoveryClient which provides a simple API for discovery clients that is not specific to Netflix, e.g.

@Autowired
+private DiscoveryClient discoveryClient;
+
+public String serviceUrl() {
+    List<ServiceInstance> list = discoveryClient.getInstances("STORES");
+    if (list != null && list.size() > 0 ) {
+        return list.get(0).getUri().toString();
+    }
+    return null;
+}
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68. Install Zookeeper
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68. Install Zookeeper

Please see the installation documentation for instructions on how to install Zookeeper.

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70. Using Spring Cloud Zookeeper with Spring Cloud Netflix Components
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70. Using Spring Cloud Zookeeper with Spring Cloud Netflix Components

Spring Cloud Netflix supplies useful tools that work regardless of which DiscoveryClient implementation is used. Feign, Turbine, Ribbon and Zuul all work with Spring Cloud Zookeeper.

70.1 Ribbon with Zookeeper

Spring Cloud Zookeeper provides an implementation of Ribbon’s ServerList. When the spring-cloud-starter-zookeeper-discovery is used, Ribbon is auto-configured to use the ZookeeperServerList by default.

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71. Spring Cloud Zookeeper and Service Registry
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71. Spring Cloud Zookeeper and Service Registry

Spring Cloud Zookeeper implements the ServiceRegistry interface allowing developers to register arbitrary service in a programmatic way.

The ServiceInstanceRegistration class offers a builder() method to create a Registration object that can be used by the ServiceRegistry.

@Autowired
+private ZookeeperServiceRegistry serviceRegistry;
+
+public void registerThings() {
+    ZookeeperRegistration registration = ServiceInstanceRegistration.builder()
+            .defaultUriSpec()
+            .address("anyUrl")
+            .port(10)
+            .name("/a/b/c/d/anotherservice")
+            .build();
+    this.serviceRegistry.register(registration);
+}

71.1 Instance Status

Netflix Eureka supports having instances registered with the server that are OUT_OF_SERVICE and not returned as active service instances. This is very useful for behaviors such as blue/green deployments. The Curator Service Discovery recipe does not support this behavior. Taking advantage of the flexible payload has let Spring Cloud Zookeeper implement OUT_OF_SERVICE by updating some specific metadata and then filtering on that metadata in the Ribbon ZookeeperServerList. The ZookeeperServerList filters out all non-null instance statuses that do not equal UP. If the instance status field is empty, it is considered UP for backwards compatibility. To change the status of an instance POST OUT_OF_SERVICE to the ServiceRegistry instance status actuator endpoint.

----
+$ echo -n OUT_OF_SERVICE | http POST http://localhost:8081/service-registry/instance-status
+----
NOTE: The above example uses the `http` command from https://httpie.org
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Spring Cloud
   Next

Spring Cloud

Table of Contents

1. Features
I. Cloud Native Applications
2. Spring Cloud Context: Application Context Services
2.1. The Bootstrap Application Context
2.2. Application Context Hierarchies
2.3. Changing the Location of Bootstrap Properties
2.4. Overriding the Values of Remote Properties
2.5. Customizing the Bootstrap Configuration
2.6. Customizing the Bootstrap Property Sources
2.7. Logging Configuration
2.8. Environment Changes
2.9. Refresh Scope
2.10. Encryption and Decryption
2.11. Endpoints
3. Spring Cloud Commons: Common Abstractions
3.1. @EnableDiscoveryClient
3.1.1. Health Indicator
3.2. ServiceRegistry
3.2.1. ServiceRegistry Auto-Registration
3.2.2. Service Registry Actuator Endpoint
3.3. Spring RestTemplate as a Load Balancer Client
3.3.1. Retrying Failed Requests
3.4. Multiple RestTemplate objects
3.5. Ignore Network Interfaces
3.6. HTTP Client Factories
3.7. Spring Cloud Compatibility Verification
II. Spring Cloud Config
4. Quick Start
4.1. Client Side Usage
5. Spring Cloud Config Server
5.1. Environment Repository
5.1.1. Git Backend
Placeholders in Git URI
Pattern Matching and Multiple Repositories
Authentication
Authentication with AWS CodeCommit
Git SSH configuration using properties
Placeholders in Git Search Paths
Force pull in Git Repositories
Deleting untracked branches in Git Repositories
5.1.2. Version Control Backend Filesystem Use
5.1.3. File System Backend
5.1.4. Vault Backend
Multiple Properties Sources
5.1.5. Sharing Configuration With All Applications
File Based Repositories
Vault Server
5.1.6. JDBC Backend
5.1.7. Composite Environment Repositories
Custom Composite Environment Repositories
5.1.8. Property Overrides
5.2. Health Indicator
5.3. Security
5.4. Encryption and Decryption
5.5. Key Management
5.6. Creating a Key Store for Testing
5.7. Using Multiple Keys and Key Rotation
5.8. Serving Encrypted Properties
6. Serving Alternative Formats
7. Serving Plain Text
8. Embedding the Config Server
9. Push Notifications and Spring Cloud Bus
10. Spring Cloud Config Client
10.1. Config First Bootstrap
10.2. Discovery First Bootstrap
10.3. Config Client Fail Fast
10.4. Config Client Retry
10.5. Locating Remote Configuration Resources
10.6. Security
10.6.1. Health Indicator
10.6.2. Providing A Custom RestTemplate
10.6.3. Vault
10.7. Vault
10.7.1. Nested Keys In Vault
III. Spring Cloud Netflix
11. Service Discovery: Eureka Clients
11.1. How to Include Eureka Client
11.2. Registering with Eureka
11.3. Authenticating with the Eureka Server
11.4. Status Page and Health Indicator
11.5. Registering a Secure Application
11.6. Eureka’s Health Checks
11.7. Eureka Metadata for Instances and Clients
11.7.1. Using Eureka on Cloud Foundry
11.7.2. Using Eureka on AWS
11.7.3. Changing the Eureka Instance ID
11.8. Using the EurekaClient
11.8.1. EurekaClient without Jersey
11.9. Alternatives to the native Netflix EurekaClient
11.10. Why is it so Slow to Register a Service?
11.11. Zones
12. Service Discovery: Eureka Server
12.1. How to Include Eureka Server
12.2. How to Run a Eureka Server
12.3. High Availability, Zones and Regions
12.4. Standalone Mode
12.5. Peer Awareness
12.6. Prefer IP Address
13. Circuit Breaker: Hystrix Clients
13.1. How to Include Hystrix
13.2. Propagating the Security Context or using Spring Scopes
13.3. Health Indicator
13.4. Hystrix Metrics Stream
14. Circuit Breaker: Hystrix Dashboard
15. Hystrix Timeouts And Ribbon Clients
15.1. How to Include Hystrix Dashboard
15.2. Turbine
15.3. Turbine Stream
16. Client Side Load Balancer: Ribbon
16.1. How to Include Ribbon
16.2. Customizing the Ribbon Client
16.3. Customizing default for all Ribbon Clients
16.4. Customizing the Ribbon Client using properties
16.5. Using Ribbon with Eureka
16.6. Example: How to Use Ribbon Without Eureka
16.7. Example: Disable Eureka use in Ribbon
16.8. Using the Ribbon API Directly
16.9. Caching of Ribbon Configuration
16.10. How to Configure Hystrix thread pools
16.11. How to Provide a Key to Ribbon’s IRule
17. Declarative REST Client: Feign
17.1. How to Include Feign
17.2. Overriding Feign Defaults
17.3. Creating Feign Clients Manually
17.4. Feign Hystrix Support
17.5. Feign Hystrix Fallbacks
17.6. Feign and @Primary
17.7. Feign Inheritance Support
17.8. Feign request/response compression
17.9. Feign logging
18. External Configuration: Archaius
19. Router and Filter: Zuul
19.1. How to Include Zuul
19.2. Embedded Zuul Reverse Proxy
19.3. Zuul Http Client
19.4. Cookies and Sensitive Headers
19.5. Ignored Headers
19.6. Management Endpoints
19.6.1. Routes Endpoint
19.6.2. Filters Endpoint
19.7. Strangulation Patterns and Local Forwards
19.8. Uploading Files through Zuul
19.9. Query String Encoding
19.10. Plain Embedded Zuul
19.11. Disable Zuul Filters
19.12. Providing Hystrix Fallbacks For Routes
19.13. Zuul Timeouts
19.13.1. Service Discovery Configuration
19.13.2. URL Configuration
19.14. Rewriting Location header
19.15. Zuul Developer Guide
19.15.1. The Zuul Servlet
19.15.2. Zuul RequestContext
19.15.3. @EnableZuulProxy vs. @EnableZuulServer
19.15.4. @EnableZuulServer Filters
19.15.5. @EnableZuulProxy Filters
19.15.6. Custom Zuul Filter examples
19.15.7. How to Write a Pre Filter
19.15.8. How to Write a Route Filter
19.15.9. How to Write a Post Filter
19.15.10. How Zuul Errors Work
19.15.11. Zuul Eager Application Context Loading
20. Polyglot support with Sidecar
21. RxJava with Spring MVC
22. Metrics: Spectator, Servo, and Atlas
22.1. Dimensional vs. Hierarchical Metrics
22.2. Default Metrics Collection
22.3. Metrics Collection: Spectator
22.3.1. Spectator Counter
22.3.2. Spectator Timer
22.3.3. Spectator Gauge
22.3.4. Spectator Distribution Summaries
22.4. Metrics Collection: Servo
22.4.1. Creating Servo Monitors
22.5. Metrics Backend: Atlas
22.5.1. Global tags
22.5.2. Using Atlas
22.6. Retrying Failed Requests
22.6.1. BackOff Policies
22.6.2. Configuration
22.6.3. Zuul
23. HTTP Clients
IV. Spring Cloud Stream
24. Introducing Spring Cloud Stream
25. Main Concepts
25.1. Application Model
25.1.1. Fat JAR
25.2. The Binder Abstraction
25.3. Persistent Publish-Subscribe Support
25.4. Consumer Groups
25.4.1. Durability
25.5. Partitioning Support
26. Programming Model
26.1. Declaring and Binding Channels
26.1.1. Triggering Binding Via @EnableBinding
26.1.2. @Input and @Output
Customizing Channel Names
Source, Sink, and Processor
26.1.3. Accessing Bound Channels
Injecting the Bound Interfaces
Injecting Channels Directly
26.1.4. Producing and Consuming Messages
Native Spring Integration Support
Spring Integration Error Channel Support
Message Channel Binders and Error Channels
Using @StreamListener for Automatic Content Type Handling
Using @StreamListener for dispatching messages to multiple methods
26.1.5. Reactive Programming Support
Reactor-based handlers
RxJava 1.x support
Reactive Sources
26.1.6. Aggregation
Configuring aggregate application
Configuring binding service properties for non self contained aggregate application
27. Binders
27.1. Producers and Consumers
27.2. Binder SPI
27.3. Binder Detection
27.3.1. Classpath Detection
27.4. Multiple Binders on the Classpath
27.5. Connecting to Multiple Systems
27.6. Binder configuration properties
28. Configuration Options
28.1. Spring Cloud Stream Properties
28.2. Binding Properties
28.2.1. Properties for Use of Spring Cloud Stream
28.2.2. Consumer properties
28.2.3. Producer Properties
28.3. Using dynamically bound destinations
29. Content Type and Transformation
29.1. MIME types
29.2. MIME types and Java types
29.3. Customizing message conversion
29.4. @StreamListener and Message Conversion
30. Schema Evolution Support
30.1. Schema Registry Client
30.1.1. Schema Registry Client Properties
30.2. Avro Schema Registry Client Message Converters
30.2.1. Avro Schema Registry Message Converter Properties
30.3. Apache Avro Message Converters
30.4. Converters with Schema Support
30.5. Schema Registry Server
30.5.1. Schema Registry Server API
Registering a New Schema
Retrieving an Existing Schema by Subject, Format, and Version
Retrieving an Existing Schema by Subject and Format
Retrieving an Existing Schema by ID
Deleting a Schema by Subject, Format, and Version
Deleting a Schema by ID
Deleting a Schema by Subject
30.5.2. Using Confluent’s Schema Registry
30.6. Schema Registration and Resolution
30.6.1. Schema Registration Process (Serialization)
30.6.2. Schema Resolution Process (Deserialization)
31. Inter-Application Communication
31.1. Connecting Multiple Application Instances
31.2. Instance Index and Instance Count
31.3. Partitioning
31.3.1. Configuring Output Bindings for Partitioning
Spring-managed custom PartitionKeyExtractorClass implementations
Configuring Input Bindings for Partitioning
32. Testing
32.1. Disabling the test binder autoconfiguration
33. Health Indicator
34. Metrics Emitter
35. Samples
36. Getting Started
36.1. Deploying Stream applications on CloudFoundry
V. Binder Implementations
37. Apache Kafka Binder
37.1. Usage
37.2. Apache Kafka Binder Overview
37.3. Configuration Options
37.3.1. Kafka Binder Properties
37.3.2. Kafka Consumer Properties
37.3.3. Kafka Producer Properties
37.3.4. Usage examples
Example: Setting autoCommitOffset false and relying on manual acking.
Example: security configuration
Using the binder with Apache Kafka 0.10
Excluding Kafka broker jar from the classpath of the binder based application
37.4. Kafka Streams Binding Capabilities of Spring Cloud Stream
37.4.1. Usage example of high level streams DSL
37.4.2. Support for interactive queries
37.4.3. Kafka Streams properties
37.5. Error Channels
37.6. Kafka Metrics
37.7. Dead-Letter Topic Processing
38. RabbitMQ Binder
38.1. Usage
38.2. RabbitMQ Binder Overview
38.3. Configuration Options
38.3.1. RabbitMQ Binder Properties
38.3.2. RabbitMQ Consumer Properties
38.3.3. Rabbit Producer Properties
38.4. Retry With the RabbitMQ Binder
38.4.1. Overview
38.4.2. Putting it All Together
38.5. Error Channels
38.6. Dead-Letter Queue Processing
38.6.1. Non-Partitioned Destinations
38.6.2. Partitioned Destinations
republishToDlq=false
republishToDlq=true
VI. Spring Cloud Bus
39. Quick Start
40. Addressing an Instance
41. Addressing all instances of a service
42. Application Context ID must be unique
43. Customizing the Message Broker
44. Tracing Bus Events
45. Broadcasting Your Own Events
45.1. Registering events in custom packages
VII. Spring Cloud Sleuth
46. Introduction
46.1. Terminology
46.2. Purpose
46.2.1. Distributed tracing with Zipkin
46.2.2. Visualizing errors
46.2.3. Live examples
46.2.4. Log correlation
JSON Logback with Logstash
46.2.5. Propagating Span Context
Baggage vs. Span Tags
46.3. Adding to the project
46.3.1. Only Sleuth (log correlation)
46.3.2. Sleuth with Zipkin via HTTP
46.3.3. Sleuth with Zipkin via RabbitMQ or Kafka
47. Additional resources
48. Features
49. Sampling
50. Instrumentation
51. Span lifecycle
51.1. Creating and closing spans
51.2. Continuing spans
51.3. Creating spans with an explicit parent
52. Naming spans
52.1. @SpanName annotation
52.2. toString() method
53. Managing spans with annotations
53.1. Rationale
53.2. Creating new spans
53.3. Continuing spans
53.4. More advanced tag setting
53.4.1. Custom extractor
53.4.2. Resolving expressions for value
53.4.3. Using toString method
54. Customizations
54.1. Spring Integration
54.2. HTTP
54.3. Example
54.4. TraceFilter
54.5. Custom SA tag in Zipkin
54.6. Custom service name
54.7. Customization of reported spans
54.8. Host locator
55. Sending spans to Zipkin
56. Span Data as Messages
56.1. Zipkin Consumer
56.2. Custom Consumer
57. Metrics
58. Integrations
58.1. Runnable and Callable
58.2. Hystrix
58.2.1. Custom Concurrency Strategy
58.2.2. Manual Command setting
58.3. RxJava
58.4. HTTP integration
58.4.1. HTTP Filter
58.4.2. HandlerInterceptor
58.4.3. Async Servlet support
58.5. HTTP client integration
58.5.1. Synchronous Rest Template
58.5.2. Asynchronous Rest Template
Multiple Asynchronous Rest Templates
58.5.3. Traverson
58.6. Feign
58.7. Asynchronous communication
58.7.1. @Async annotated methods
58.7.2. @Scheduled annotated methods
58.7.3. Executor, ExecutorService and ScheduledExecutorService
Customization of Executors
58.8. Messaging
58.9. Zuul
58.10. Spring Cloud Function
59. Running examples
VIII. Spring Cloud Consul
60. Install Consul
61. Consul Agent
62. Service Discovery with Consul
62.1. How to activate
62.2. Registering with Consul
62.3. HTTP Health Check
62.3.1. Metadata and Consul tags
62.3.2. Making the Consul Instance ID Unique
62.4. Looking up services
62.4.1. Using Ribbon
62.4.2. Using the DiscoveryClient
63. Distributed Configuration with Consul
63.1. How to activate
63.2. Customizing
63.3. Config Watch
63.4. YAML or Properties with Config
63.5. git2consul with Config
63.6. Fail Fast
64. Consul Retry
65. Spring Cloud Bus with Consul
65.1. How to activate
66. Circuit Breaker with Hystrix
67. Hystrix metrics aggregation with Turbine and Consul
IX. Spring Cloud Zookeeper
68. Install Zookeeper
69. Service Discovery with Zookeeper
69.1. How to activate
69.2. Registering with Zookeeper
69.3. Using the DiscoveryClient
70. Using Spring Cloud Zookeeper with Spring Cloud Netflix Components
70.1. Ribbon with Zookeeper
71. Spring Cloud Zookeeper and Service Registry
71.1. Instance Status
72. Zookeeper Dependencies
72.1. Using the Zookeeper Dependencies
72.2. How to activate Zookeeper Dependencies
72.3. Setting up Zookeeper Dependencies
72.3.1. Aliases
72.3.2. Path
72.3.3. Load balancer type
72.3.4. Content-Type template and version
72.3.5. Default headers
72.3.6. Obligatory dependencies
72.3.7. Stubs
72.4. Configuring Spring Cloud Zookeeper Dependencies
73. Spring Cloud Zookeeper Dependency Watcher
73.1. How to activate
73.2. Registering a listener
73.3. Presence Checker
74. Distributed Configuration with Zookeeper
74.1. How to activate
74.2. Customizing
74.3. ACLs
X. Spring Boot Cloud CLI
75. Installation
76. Running Spring Cloud Services in Development
76.1. Adding Additional Applications
77. Writing Groovy Scripts and Running Applications
78. Encryption and Decryption
XI. Spring Cloud Security
79. Quickstart
79.1. OAuth2 Single Sign On
79.2. OAuth2 Protected Resource
80. More Detail
80.1. Single Sign On
80.2. Token Relay
80.2.1. Client Token Relay
80.2.2. Client Token Relay in Zuul Proxy
80.2.3. Resource Server Token Relay
81. Configuring Authentication Downstream of a Zuul Proxy
XII. Spring Cloud for Cloud Foundry
82. Discovery
83. Single Sign On
XIII. Spring Cloud Contract
84. Spring Cloud Contract
85. Spring Cloud Contract Verifier Introduction
85.1. Why a Contract Verifier?
85.1.1. Testing issues
85.2. Purposes
85.3. How It Works
85.3.1. Defining the contract
85.3.2. Client Side
85.3.3. Server Side
85.4. Step-by-step Guide to Consumer Driven Contracts (CDC)
85.4.1. Technical note
85.4.2. Consumer side (Loan Issuance)
85.4.3. Producer side (Fraud Detection server)
85.4.4. Consumer Side (Loan Issuance) Final Step
85.5. Dependencies
85.6. Additional Links
85.6.1. Spring Cloud Contract video
85.6.2. Readings
85.7. Samples
86. Spring Cloud Contract FAQ
86.1. Why use Spring Cloud Contract Verifier and not X ?
86.2. I don’t want to write a contract in Groovy!
86.3. What is this value(consumer(), producer()) ?
86.4. How to do Stubs versioning?
86.4.1. API Versioning
86.4.2. JAR versioning
86.4.3. Dev or prod stubs
86.5. Common repo with contracts
86.5.1. Repo structure
86.5.2. Workflow
86.5.3. Consumer
86.5.4. Producer
86.6. Can I have multiple base classes for tests?
86.7. How can I debug the request/response being sent by the generated tests client?
86.7.1. How can I debug the mapping/request/response being sent by WireMock?
86.7.2. How can I see what got registered in the HTTP server stub?
86.7.3. Can I reference the request from the response?
86.7.4. Can I reference text from file?
87. Spring Cloud Contract Verifier Setup
87.1. Gradle Project
87.1.1. Prerequisites
87.1.2. Add Gradle Plugin with Dependencies
87.1.3. Gradle and Rest Assured 2.0
87.1.4. Snapshot Versions for Gradle
87.1.5. Add stubs
87.1.6. Run the Plugin
87.1.7. Default Setup
87.1.8. Configure Plugin
87.1.9. Configuration Options
87.1.10. Single Base Class for All Tests
87.1.11. Different Base Classes for Contracts
87.1.12. Invoking Generated Tests
87.1.13. Spring Cloud Contract Verifier on the Consumer Side
87.2. Maven Project
87.2.1. Add maven plugin
87.2.2. Maven and Rest Assured 2.0
87.2.3. Snapshot versions for Maven
87.2.4. Add stubs
87.2.5. Run plugin
87.2.6. Configure plugin
87.2.7. Configuration Options
87.2.8. Single Base Class for All Tests
87.2.9. Different base classes for contracts
87.2.10. Invoking generated tests
87.2.11. Maven Plugin and STS
87.3. Stubs and Transitive Dependencies
87.4. CI Server setup
87.5. Scenarios
87.6. Docker Project
87.6.1. Short intro to Maven, JARs and Binary storage
87.6.2. How it works
Environment Variables
87.6.3. Example of usage
87.6.4. Server side (nodejs)
88. Spring Cloud Contract Verifier Messaging
88.1. Integrations
88.2. Manual Integration Testing
88.3. Publisher-Side Test Generation
88.3.1. Scenario 1: No Input Message
88.3.2. Scenario 2: Output Triggered by Input
88.3.3. Scenario 3: No Output Message
88.4. Consumer Stub Generation
89. Spring Cloud Contract Stub Runner
89.1. Snapshot versions
89.2. Publishing Stubs as JARs
89.3. Stub Runner Core
89.3.1. Retrieving stubs
Stub downloading
Classpath scanning
89.3.2. Running stubs
Running using main app
HTTP Stubs
Viewing registered mappings
Messaging Stubs
89.4. Stub Runner JUnit Rule
89.4.1. Maven settings
89.4.2. Providing fixed ports
89.4.3. Fluent API
89.4.4. Stub Runner with Spring
89.5. Stub Runner Spring Cloud
89.5.1. Stubbing Service Discovery
Test profiles and service discovery
89.5.2. Additional Configuration
89.6. Stub Runner Boot Application
89.6.1. How to use it?
Stub Runner Server
Stub Runner Server Fat Jar
Spring Cloud CLI
89.6.2. Endpoints
HTTP
Messaging
89.6.3. Example
89.6.4. Stub Runner Boot with Service Discovery
89.7. Stubs Per Consumer
89.8. Common
89.8.1. Common Properties for JUnit and Spring
89.8.2. Stub Runner Stubs IDs
89.9. Stub Runner Docker
89.9.1. How to use it
89.9.2. Example of client side usage in a non JVM project
90. Stub Runner for Messaging
90.1. Stub triggering
90.1.1. Trigger by Label
90.1.2. Trigger by Group and Artifact Ids
90.1.3. Trigger by Artifact Ids
90.1.4. Trigger All Messages
90.2. Stub Runner Camel
90.2.1. Adding the Runner to the Project
90.2.2. Disabling the functionality
Scenario 1 (no input message)
Scenario 2 (output triggered by input)
Scenario 3 (input with no output)
90.3. Stub Runner Integration
90.3.1. Adding the Runner to the Project
90.3.2. Disabling the functionality
Scenario 1 (no input message)
Scenario 2 (output triggered by input)
Scenario 3 (input with no output)
90.4. Stub Runner Stream
90.4.1. Adding the Runner to the Project
90.4.2. Disabling the functionality
Scenario 1 (no input message)
Scenario 2 (output triggered by input)
Scenario 3 (input with no output)
90.5. Stub Runner Spring AMQP
90.5.1. Adding the Runner to the Project
Triggering the message
Spring AMQP Test Configuration
91. Contract DSL
91.1. Limitations
91.2. Common Top-Level elements
91.2.1. Description
91.2.2. Name
91.2.3. Ignoring Contracts
91.2.4. Passing Values from Files
91.2.5. HTTP Top-Level Elements
91.3. Request
91.4. Response
91.5. Dynamic properties
91.5.1. Dynamic properties inside the body
91.5.2. Regular expressions
91.5.3. Passing Optional Parameters
91.5.4. Executing Custom Methods on the Server Side
91.5.5. Referencing the Request from the Response
91.5.6. Registering Your Own WireMock Extension
91.5.7. Dynamic Properties in the Matchers Sections
91.6. JAX-RS Support
91.7. Async Support
91.8. Working with Context Paths
91.9. Messaging Top-Level Elements
91.9.1. Output Triggered by a Method
91.9.2. Output Triggered by a Message
91.9.3. Consumer/Producer
91.9.4. Common
91.10. Multiple Contracts in One File
92. Customization
92.1. Extending the DSL
92.1.1. Common JAR
92.1.2. Adding the Dependency to the Project
92.1.3. Test the Dependency in the Project’s Dependencies
92.1.4. Test a Dependency in the Plugin’s Dependencies
92.1.5. Referencing classes in DSLs
93. Using the Pluggable Architecture
93.1. Custom Contract Converter
93.1.1. Pact Converter
93.1.2. Pact Contract
93.1.3. Pact for Producers
93.1.4. Pact for Consumers
93.2. Using the Custom Test Generator
93.3. Using the Custom Stub Generator
93.4. Using the Custom Stub Runner
93.5. Using the Custom Stub Downloader
94. Spring Cloud Contract WireMock
94.1. Registering Stubs Automatically
94.2. Using Files to Specify the Stub Bodies
94.3. Alternative: Using JUnit Rules
94.4. Relaxed SSL Validation for Rest Template
94.5. WireMock and Spring MVC Mocks
94.6. Customization of WireMock configuration
94.7. Generating Stubs using REST Docs
94.8. Generating Contracts by Using REST Docs
95. Migrations
95.1. 1.0.x → 1.1.x
95.1.1. New structure of generated stubs
95.2. 1.1.x → 1.2.x
95.2.1. Custom HttpServerStub
95.2.2. New packages for generated tests
95.2.3. New Methods in TemplateProcessor
95.2.4. RestAssured 3.0
96. Links
XIV. Spring Cloud Vault
97. Quick Start
98. Client Side Usage
98.1. Authentication
99. Authentication methods
99.1. Token authentication
99.2. AppId authentication
99.2.1. Custom UserId
99.3. AppRole authentication
99.4. AWS-EC2 authentication
99.5. AWS-IAM authentication
99.6. TLS certificate authentication
99.7. Cubbyhole authentication
99.8. Kubernetes authentication
100. Secret Backends
100.1. Generic Backend
100.2. Consul
100.3. RabbitMQ
100.4. AWS
101. Database backends
101.1. Apache Cassandra
101.2. MongoDB
101.3. MySQL
101.4. PostgreSQL
102. Configure PropertySourceLocator behavior
103. Service Registry Configuration
104. Vault Client Fail Fast
105. Vault Client SSL configuration
106. Lease lifecycle management (renewal and revocation)
XV. Spring Cloud Function
107. Introduction
108. Getting Started
109. Building and Running a Function
110. Function Catalog and Flexible Function Signatures
111. Standalone Web Applications
112. Standalone Streaming Applications
113. Deploying a Packaged Function
114. Dynamic Compilation
115. Serverless Platform Adapters
115.1. AWS Lambda
115.1.1. Introduction
115.1.2. Notes on JAR Layout
115.1.3. Upload
115.1.4. Platfom Specific Features
HTTP and API Gateway
115.2. Azure Functions
115.2.1. Notes on JAR Layout
115.2.2. JSON Configuration
115.2.3. Build
115.2.4. Running the sample
115.3. Apache Openwhisk
115.3.1. Quick Start
XVI. Appendix: Compendium of Configuration Properties
   Next
   
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106. Lease lifecycle management (renewal and revocation)
Prev Part XIV. Spring Cloud Vault Next

106. Lease lifecycle management (renewal and revocation)

With every secret, Vault creates a lease: +metadata containing information such as a time duration, +renewability, and more.

Vault promises that the data will be valid for the given duration, +or Time To Live (TTL). Once the lease is expired, Vault can +revoke the data, and the consumer of the secret can no longer +be certain that it is valid.

Spring Cloud Vault maintains a lease lifecycle beyond +the creation of login tokens and secrets. That said, +login tokens and secrets associated with a lease +are scheduled for renewal just before the lease expires +until terminal expiry. +Application shutdown revokes obtained login tokens and renewable +leases.

Secret service and database backends (such as MongoDB or MySQL) +usually generate a renewable lease so generated credentials will +be disabled on application shutdown.

[Note]Note

Static tokens are not renewed or revoked.

Lease renewal and revocation is enabled by default and can +be disabled by setting spring.cloud.vault.config.lifecycle.enabled +to false. This is not recommended as leases can expire and +Spring Cloud Vault cannot longer access Vault or services +using generated credentials and valid credentials remain active +after application shutdown.

spring.cloud.vault:
+    config.lifecycle.enabled: true

See also: Vault Documentation: Lease, Renew, and Revoke

Prev Up Next
105. Vault Client SSL configuration Home Part XV. Spring Cloud Function
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99. Authentication methods
Prev Part XIV. Spring Cloud Vault Next

99. Authentication methods

Different organizations have different requirements for security +and authentication. Vault reflects that need by shipping multiple authentication +methods. Spring Cloud Vault supports token and AppId authentication.

99.1 Token authentication

Tokens are the core method for authentication within Vault. +Token authentication requires a static token to be provided using the +Bootstrap Application Context.

[Note]Note

Token authentication is the default authentication method. +If a token is disclosed an unintended party gains access to Vault and +can access secrets for the intended client.

Example 99.1. bootstrap.yml

spring.cloud.vault:
+    authentication: TOKEN
+    token: 00000000-0000-0000-0000-000000000000

  • authentication setting this value to TOKEN selects the Token +authentication method
  • token sets the static token to use

See also: Vault Documentation: Tokens

99.2 AppId authentication

Vault supports AppId +authentication that consists of two hard to guess tokens. The AppId +defaults to spring.application.name that is statically configured. +The second token is the UserId which is a part determined by the application, +usually related to the runtime environment. IP address, Mac address or a +Docker container name are good examples. Spring Cloud Vault Config supports +IP address, Mac address and static UserId’s (e.g. supplied via System properties). +The IP and Mac address are represented as Hex-encoded SHA256 hash.

IP address-based UserId’s use the local host’s IP address.

Example 99.2. bootstrap.yml using SHA256 IP-Address UserId’s

spring.cloud.vault:
+    authentication: APPID
+    app-id:
+        user-id: IP_ADDRESS

  • authentication setting this value to APPID selects the AppId +authentication method
  • app-id-path sets the path of the AppId mount to use
  • user-id sets the UserId method. Possible values are IP_ADDRESS, +MAC_ADDRESS or a class name implementing a custom AppIdUserIdMechanism

The corresponding command to generate the IP address UserId from a command line is:

$ echo -n 192.168.99.1 | sha256sum
[Note]Note

Including the line break of echo leads to a different hash value +so make sure to include the -n flag.

Mac address-based UserId’s obtain their network device from the +localhost-bound device. The configuration also allows specifying +a network-interface hint to pick the right device. The value of +network-interface is optional and can be either an interface +name or interface index (0-based).

Example 99.3. bootstrap.yml using SHA256 Mac-Address UserId’s

spring.cloud.vault:
+    authentication: APPID
+    app-id:
+        user-id: MAC_ADDRESS
+        network-interface: eth0

  • network-interface sets network interface to obtain the physical address

The corresponding command to generate the IP address UserId from a command line is:

$ echo -n 0AFEDE1234AC | sha256sum
[Note]Note

The Mac address is specified uppercase and without colons. +Including the line break of echo leads to a different hash value +so make sure to include the -n flag.

99.2.1 Custom UserId

The UserId generation is an open mechanism. You can set +spring.cloud.vault.app-id.user-id to any string and the configured +value will be used as static UserId.

A more advanced approach lets you set spring.cloud.vault.app-id.user-id to a +classname. This class must be on your classpath and must implement +the org.springframework.cloud.vault.AppIdUserIdMechanism interface +and the createUserId method. Spring Cloud Vault will obtain the UserId +by calling createUserId each time it authenticates using AppId to +obtain a token.

Example 99.4. bootstrap.yml

spring.cloud.vault:
+    authentication: APPID
+    app-id:
+        user-id: com.examlple.MyUserIdMechanism

Example 99.5. MyUserIdMechanism.java

public class MyUserIdMechanism implements AppIdUserIdMechanism {
+
+  @Override
+  public String createUserId() {
+    String userId = ...
+    return userId;
+  }
+}

See also: Vault Documentation: Using the App ID auth backend

99.3 AppRole authentication

AppRole is intended for machine +authentication, like the deprecated (since Vault 0.6.1) Section 99.2, “AppId authentication”. +AppRole authentication consists of two hard to guess (secret) tokens: RoleId and SecretId.

Spring Vault supports AppRole authentication by providing either RoleId only +or together with a provided SecretId (push or pull mode).

RoleId and optionally SecretId must be provided by configuration, +Spring Vault will not look up these or create a custom SecretId.

Example 99.6. bootstrap.yml with AppRole authentication properties

spring.cloud.vault:
+    authentication: APPROLE
+    app-role:
+        role-id: bde2076b-cccb-3cf0-d57e-bca7b1e83a52

  • role-id sets the RoleId.

Example 99.7. bootstrap.yml with all AppRole authentication properties

spring.cloud.vault:
+    authentication: APPROLE
+    app-role:
+        role-id: bde2076b-cccb-3cf0-d57e-bca7b1e83a52
+        secret-id: 1696536f-1976-73b1-b241-0b4213908d39
+        app-auth-path: approle

  • role-id sets the RoleId.
  • secret-id sets the SecretId. SecretId can be omitted if AppRole is configured without requiring SecretId (See bind_secret_id)
  • approle-path sets the path of the approle authentication mount to use

See also: Vault Documentation: Using the AppRole auth backend

99.4 AWS-EC2 authentication

The aws-ec2 +auth backend provides a secure introduction mechanism +for AWS EC2 instances, allowing automated retrieval of a Vault +token. Unlike most Vault authentication backends, this backend +does not require first-deploying, or provisioning security-sensitive +credentials (tokens, username/password, client certificates, etc.). +Instead, it treats AWS as a Trusted Third Party and uses the +cryptographically signed dynamic metadata information that uniquely +represents each EC2 instance.

Example 99.8. bootstrap.yml using AWS-EC2 Authentication

spring.cloud.vault:
+    authentication: AWS_EC2

AWS-EC2 authentication enables nonce by default to follow +the Trust On First Use (TOFU) principle. Any unintended party that +gains access to the PKCS#7 identity metadata can authenticate +against Vault.

During the first login, Spring Cloud Vault generates a nonce +that is stored in the auth backend aside the instance Id. +Re-authentication requires the same nonce to be sent. Any other +party does not have the nonce and can raise an alert in Vault for +further investigation.

The nonce is kept in memory and is lost during application restart. +You can configure a static nonce with spring.cloud.vault.aws-ec2.nonce.

AWS-EC2 authentication roles are optional and default to the AMI. +You can configure the authentication role by setting the +spring.cloud.vault.aws-ec2.role property.

Example 99.9. bootstrap.yml with configured role

spring.cloud.vault:
+    authentication: AWS_EC2
+    aws-ec2:
+        role: application-server

Example 99.10. bootstrap.yml with all AWS EC2 authentication properties

spring.cloud.vault:
+    authentication: AWS_EC2
+    aws-ec2:
+        role: application-server
+        aws-ec2-path: aws-ec2
+        identity-document: http://...
+        nonce: my-static-nonce

  • authentication setting this value to AWS_EC2 selects the AWS EC2 +authentication method
  • role sets the name of the role against which the login is being attempted.
  • aws-ec2-path sets the path of the AWS EC2 mount to use
  • identity-document sets URL of the PKCS#7 AWS EC2 identity document
  • nonce used for AWS-EC2 authentication. An empty nonce defaults to nonce generation

See also: Vault Documentation: Using the aws auth backend

99.5 AWS-IAM authentication

The aws backend provides a secure +authentication mechanism for AWS IAM roles, allowing the automatic authentication with +vault based on the current IAM role of the running application. + Unlike most Vault authentication backends, this backend +does not require first-deploying, or provisioning security-sensitive +credentials (tokens, username/password, client certificates, etc.). +Instead, it treats AWS as a Trusted Third Party and uses the +4 pieces of information signed by the caller with their IAM credentials + to verify that the caller is indeed using that IAM role.

The current IAM role the application is running in is automatically calculated. +If you are running your application on AWS ECS then the application +will use the IAM role assigned to the ECS task of the running container. +If you are running your application naked on top of an EC2 instance then +the IAM role used will be the one assigned to the EC2 instance.

When using the AWS-IAM authentication you must create a role in Vault +and assign it to your IAM role. An empty role defaults to +the friendly name the current IAM role.

Example 99.11. bootstrap.yml with required AWS-IAM Authentication properties

spring.cloud.vault:
+    authentication: AWS_IAM

Example 99.12. bootstrap.yml with all AWS-IAM Authentication properties

spring.cloud.vault:
+    authentication: AWS_IAM
+    aws-iam:
+        role: my-dev-role
+        aws-path: aws
+        server-id: some.server.name

  • role sets the name of the role against which the login is being attempted. This should be bound to your IAM role. If one is not supplied then the friendly name of the current IAM user will be used as the vault role.
  • aws-path sets the path of the AWS mount to use
  • server-id sets the value to use for the X-Vault-AWS-IAM-Server-ID header preventing certain types of replay attacks.

AWS-IAM requires the AWS Java SDK dependency (com.amazonaws:aws-java-sdk-core) +as the authentication implementation uses AWS SDK types for credentials and request signing.

See also: Vault Documentation: Using the aws auth backend

99.6 TLS certificate authentication

The cert auth backend allows authentication using SSL/TLS client +certificates that are either signed by a CA or self-signed.

To enable cert authentication you need to:

  1. Use SSL, see Chapter 105, Vault Client SSL configuration
  2. Configure a Java Keystore that contains the client +certificate and the private key
  3. Set the spring.cloud.vault.authentication to CERT

Example 99.13. bootstrap.yml

spring.cloud.vault:
+    authentication: CERT
+    ssl:
+        key-store: classpath:keystore.jks
+        key-store-password: changeit
+        cert-auth-path: cert

See also: Vault Documentation: Using the Cert auth backend

99.7 Cubbyhole authentication

Cubbyhole authentication uses Vault primitives to provide a secured authentication +workflow. Cubbyhole authentication uses tokens as primary login method. +An ephemeral token is used to obtain a second, login VaultToken from Vault’s +Cubbyhole secret backend. The login token is usually longer-lived and used to +interact with Vault. The login token will be retrieved from a wrapped +response stored at /cubbyhole/response.

Creating a wrapped token

[Note]Note

Response Wrapping for token creation requires Vault 0.6.0 or higher.

Example 99.14. Creating and storing tokens

$ vault token-create -wrap-ttl="10m"
+Key                            Value
+---                            -----
+wrapping_token:                397ccb93-ff6c-b17b-9389-380b01ca2645
+wrapping_token_ttl:            0h10m0s
+wrapping_token_creation_time:  2016-09-18 20:29:48.652957077 +0200 CEST
+wrapped_accessor:              46b6aebb-187f-932a-26d7-4f3d86a68319

Example 99.15. bootstrap.yml

spring.cloud.vault:
+    authentication: CUBBYHOLE
+    token: 397ccb93-ff6c-b17b-9389-380b01ca2645

See also:

99.8 Kubernetes authentication

Kubernetes authentication mechanism (since Vault 0.8.3) allows to authenticate with Vault using a Kubernetes Service Account Token. +The authentication is role based and the role is bound to a service account name and a namespace.

A file containing a JWT token for a pod’s service account is automatically mounted at /var/run/secrets/kubernetes.io/serviceaccount/token.

Example 99.16. bootstrap.yml with all Kubernetes authentication properties

spring.cloud.vault:
+    authentication: KUBERNETES
+    kubernetes:
+        role: my-dev-role
+        service-account-token-file: /var/run/secrets/kubernetes.io/serviceaccount/token

  • role sets the Role.
  • service-account-token-file sets the location of the file containing the Kubernetes Service Account Token. Defaults to /var/run/secrets/kubernetes.io/serviceaccount/token.

See also:

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98. Client Side Usage Home 100. Secret Backends
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102. Configure PropertySourceLocator behavior
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102. Configure PropertySourceLocator behavior

Spring Cloud Vault uses property-based configuration to create PropertySources +for generic and discovered secret backends.

Discovered backends provide VaultSecretBackendDescriptor beans to describe the configuration +state to use secret backend as PropertySource. A SecretBackendMetadataFactory is required +to create a SecretBackendMetadata object which contains path, name and property transformation +configuration.

SecretBackendMetadata is used to back a particular PropertySource.

You can register an arbitrary number of beans implementing VaultConfigurer for customization. +Default generic and discovered backend registration is disabled if Spring Cloud Vault discovers +at least one VaultConfigurer bean. You can however enable default registration with +SecretBackendConfigurer.registerDefaultGenericSecretBackends() and SecretBackendConfigurer.registerDefaultDiscoveredSecretBackends().

public class CustomizationBean implements VaultConfigurer {
+
+    @Override
+    public void addSecretBackends(SecretBackendConfigurer configurer) {
+
+        configurer.add("secret/my-application");
+
+        configurer.registerDefaultGenericSecretBackends(false);
+        configurer.registerDefaultDiscoveredSecretBackends(true);
+    }
+}
[Note]Note

All customization is required to happen in the bootstrap context. Add your configuration +classes to META-INF/spring.factories at org.springframework.cloud.bootstrap.BootstrapConfiguration +in your application.

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101. Database backends Home 103. Service Registry Configuration
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101. Database backends
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101. Database backends

Vault supports several database secret backends to generate database +credentials dynamically based on configured roles. This means +services that need to access a database no longer need to configure +credentials: they can request them from Vault, and use Vault’s leasing +mechanism to more easily roll keys.

Spring Cloud Vault integrates with these backends:

Using a database secret backend requires to enable the +backend in the configuration and the spring-cloud-vault-config-databases +dependency.

Vault ships since 0.7.1 with a dedicated database secret backend that allows +database integration via plugins. You can use that specific backend by adapting +one of the JDBC database properties above. Make sure to specify the appropriate +backend path, e.g. spring.cloud.vault.mysql.role.backend=database.

Example 101.1. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-databases</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

[Note]Note

Enabling multiple JDBC-compliant databases will generate credentials +and store them by default in the same property keys hence property names for +JDBC secrets need to be configured separately.

101.1 Apache Cassandra

Spring Cloud Vault can obtain credentials for Apache Cassandra. +The integration can be enabled by setting +spring.cloud.vault.cassandra.enabled=true (default false) and +providing the role name with spring.cloud.vault.cassandra.role=….

Username and password are stored in spring.data.cassandra.username +and spring.data.cassandra.password so using Spring Boot will pick +up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.cassandra.username-property and +spring.cloud.vault.cassandra.password-property.

spring.cloud.vault:
+    cassandra:
+        enabled: true
+        role: readonly
+        backend: cassandra
+        username-property: spring.data.cassandra.username
+        password-property: spring.data.cassandra.username
  • enabled setting this value to true enables the Cassandra backend config usage
  • role sets the role name of the Cassandra role definition
  • backend sets the path of the Cassandra mount to use
  • username-property sets the property name in which the Cassandra username is stored
  • password-property sets the property name in which the Cassandra password is stored

See also: Vault Documentation: Setting up Apache Cassandra with Vault

101.2 MongoDB

Spring Cloud Vault can obtain credentials for MongoDB. +The integration can be enabled by setting +spring.cloud.vault.mongodb.enabled=true (default false) and +providing the role name with spring.cloud.vault.mongodb.role=….

Username and password are stored in spring.data.mongodb.username +and spring.data.mongodb.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.mongodb.username-property and +spring.cloud.vault.mongodb.password-property.

spring.cloud.vault:
+    mongodb:
+        enabled: true
+        role: readonly
+        backend: mongodb
+        username-property: spring.data.mongodb.username
+        password-property: spring.data.mongodb.password
  • enabled setting this value to true enables the MongodB backend config usage
  • role sets the role name of the MongoDB role definition
  • backend sets the path of the MongoDB mount to use
  • username-property sets the property name in which the MongoDB username is stored
  • password-property sets the property name in which the MongoDB password is stored

See also: Vault Documentation: Setting up MongoDB with Vault

101.3 MySQL

Spring Cloud Vault can obtain credentials for MySQL. +The integration can be enabled by setting +spring.cloud.vault.mysql.enabled=true (default false) and +providing the role name with spring.cloud.vault.mysql.role=….

Username and password are stored in spring.datasource.username +and spring.datasource.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.mysql.username-property and +spring.cloud.vault.mysql.password-property.

spring.cloud.vault:
+    mysql:
+        enabled: true
+        role: readonly
+        backend: mysql
+        username-property: spring.datasource.username
+        password-property: spring.datasource.username
  • enabled setting this value to true enables the MySQL backend config usage
  • role sets the role name of the MySQL role definition
  • backend sets the path of the MySQL mount to use
  • username-property sets the property name in which the MySQL username is stored
  • password-property sets the property name in which the MySQL password is stored

See also: Vault Documentation: Setting up MySQL with Vault

101.4 PostgreSQL

Spring Cloud Vault can obtain credentials for PostgreSQL. +The integration can be enabled by setting +spring.cloud.vault.postgresql.enabled=true (default false) and +providing the role name with spring.cloud.vault.postgresql.role=….

Username and password are stored in spring.datasource.username +and spring.datasource.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.postgresql.username-property and +spring.cloud.vault.postgresql.password-property.

spring.cloud.vault:
+    postgresql:
+        enabled: true
+        role: readonly
+        backend: postgresql
+        username-property: spring.datasource.username
+        password-property: spring.datasource.username
  • enabled setting this value to true enables the PostgreSQL backend config usage
  • role sets the role name of the PostgreSQL role definition
  • backend sets the path of the PostgreSQL mount to use
  • username-property sets the property name in which the PostgreSQL username is stored
  • password-property sets the property name in which the PostgreSQL password is stored

See also: Vault Documentation: Setting up PostgreSQL with Vault

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100. Secret Backends Home 102. Configure PropertySourceLocator behavior
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100. Secret Backends
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100. Secret Backends

100.1 Generic Backend

Spring Cloud Vault supports at the basic level the generic secret +backend. The generic secret backend allows storage of arbitrary +values as key-value store. A single context can store one or many +key-value tuples. Contexts can be organized hierarchically. +Spring Cloud Vault allows using the Application name +and a default context name (application) in combination with active +profiles.

/secret/{application}/{profile}
+/secret/{application}
+/secret/{default-context}/{profile}
+/secret/{default-context}

The application name is determined by the properties:

  • spring.cloud.vault.generic.application-name
  • spring.cloud.vault.application-name
  • spring.application.name

Secrets can be obtained from other folders within the generic backend by adding their +paths to the application name, separated by commas. For example, given the application +name usefulapp,mysql1,projectx/aws, each of these folders will be used:

  • /secret/usefulapp
  • /secret/mysql1
  • /secret/projectx/aws

Spring Cloud Vault adds all active profiles to the list of possible context paths. +No active profiles will skip accessing contexts with a profile name.

Properties are exposed like they are stored (i.e. without additional prefixes).

spring.cloud.vault:
+    generic:
+        enabled: true
+        backend: secret
+        profile-separator: '/'
+        default-context: application
+        application-name: my-app
  • enabled setting this value to false disables the secret backend +config usage
  • backend sets the path of the secret mount to use
  • default-context sets the context name used by all applications
  • application-name overrides the application name for use in the generic backend
  • profile-separator separates the profile name from the context in +property sources with profiles

See also: Vault Documentation: Using the generic secret backend

100.2 Consul

Spring Cloud Vault can obtain credentials for HashiCorp Consul. +The Consul integration requires the spring-cloud-vault-config-consul +dependency.

Example 100.1. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-consul</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

The integration can be enabled by setting +spring.cloud.vault.consul.enabled=true (default false) and +providing the role name with spring.cloud.vault.consul.role=….

The obtained token is stored in spring.cloud.consul.token +so using Spring Cloud Consul can pick up the generated +credentials without further configuration. You can configure +the property name by setting spring.cloud.vault.consul.token-property.

spring.cloud.vault:
+    consul:
+        enabled: true
+        role: readonly
+        backend: consul
+        token-property: spring.cloud.consul.token
  • enabled setting this value to true enables the Consul backend config usage
  • role sets the role name of the Consul role definition
  • backend sets the path of the Consul mount to use
  • token-property sets the property name in which the Consul ACL token is stored

See also: Vault Documentation: Setting up Consul with Vault

100.3 RabbitMQ

Spring Cloud Vault can obtain credentials for RabbitMQ.

The RabbitMQ integration requires the spring-cloud-vault-config-rabbitmq +dependency.

Example 100.2. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-rabbitmq</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

The integration can be enabled by setting +spring.cloud.vault.rabbitmq.enabled=true (default false) +and providing the role name with spring.cloud.vault.rabbitmq.role=….

Username and password are stored in spring.rabbitmq.username +and spring.rabbitmq.password so using Spring Boot will pick up the generated +credentials without further configuration. You can configure the property names +by setting spring.cloud.vault.rabbitmq.username-property and +spring.cloud.vault.rabbitmq.password-property.

spring.cloud.vault:
+    rabbitmq:
+        enabled: true
+        role: readonly
+        backend: rabbitmq
+        username-property: spring.rabbitmq.username
+        password-property: spring.rabbitmq.password
  • enabled setting this value to true enables the RabbitMQ backend config usage
  • role sets the role name of the RabbitMQ role definition
  • backend sets the path of the RabbitMQ mount to use
  • username-property sets the property name in which the RabbitMQ username is stored
  • password-property sets the property name in which the RabbitMQ password is stored

See also: Vault Documentation: Setting up RabbitMQ with Vault

100.4 AWS

Spring Cloud Vault can obtain credentials for AWS.

The AWS integration requires the spring-cloud-vault-config-aws +dependency.

Example 100.3. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-aws</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

The integration can be enabled by setting +spring.cloud.vault.aws=true (default false) +and providing the role name with spring.cloud.vault.aws.role=….

The access key and secret key are stored in cloud.aws.credentials.accessKey +and cloud.aws.credentials.secretKey so using Spring Cloud AWS will pick up the generated +credentials without further configuration. You can configure the property names +by setting spring.cloud.vault.aws.access-key-property and +spring.cloud.vault.aws.secret-key-property.

spring.cloud.vault:
+    aws:
+        enabled: true
+        role: readonly
+        backend: aws
+        access-key-property: cloud.aws.credentials.accessKey
+        secret-key-property: cloud.aws.credentials.secretKey
  • enabled setting this value to true enables the AWS backend config usage
  • role sets the role name of the AWS role definition
  • backend sets the path of the AWS mount to use
  • access-key-property sets the property name in which the AWS access key is stored
  • secret-key-property sets the property name in which the AWS secret key is stored

See also: Vault Documentation: Setting up AWS with Vault

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99. Authentication methods Home 101. Database backends
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104. Vault Client Fail Fast
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104. Vault Client Fail Fast

In some cases, it may be desirable to fail startup of a service if +it cannot connect to the Vault Server. If this is the desired +behavior, set the bootstrap configuration property +spring.cloud.vault.fail-fast=true and the client will halt with +an Exception.

spring.cloud.vault:
+    fail-fast: true
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103. Service Registry Configuration Home 105. Vault Client SSL configuration
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105. Vault Client SSL configuration
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105. Vault Client SSL configuration

SSL can be configured declaratively by setting various properties. +You can set either javax.net.ssl.trustStore to configure +JVM-wide SSL settings or spring.cloud.vault.ssl.trust-store +to set SSL settings only for Spring Cloud Vault Config.

spring.cloud.vault:
+    ssl:
+        trust-store: classpath:keystore.jks
+        trust-store-password: changeit
  • trust-store sets the resource for the trust-store. SSL-secured Vault +communication will validate the Vault SSL certificate with the specified +trust-store.
  • trust-store-password sets the trust-store password

Please note that configuring spring.cloud.vault.ssl.* can be only +applied when either Apache Http Components or the OkHttp client +is on your class-path.

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104. Vault Client Fail Fast Home 106. Lease lifecycle management (renewal and revocation)
\ No newline at end of file diff --git a/Edgware.SR6/single/css/highlight.css b/Edgware.SR6/single/css/highlight.css new file mode 100644 index 00000000..ffefef72 --- /dev/null +++ b/Edgware.SR6/single/css/highlight.css @@ -0,0 +1,35 @@ +/* + code highlight CSS resemblign the Eclipse IDE default color schema + @author Costin Leau +*/ + +.hl-keyword { + color: #7F0055; + font-weight: bold; +} + +.hl-comment { + color: #3F5F5F; + font-style: italic; +} + +.hl-multiline-comment { + color: #3F5FBF; + font-style: italic; +} + +.hl-tag { + color: #3F7F7F; +} + +.hl-attribute { + color: #7F007F; +} + +.hl-value { + color: #2A00FF; +} + +.hl-string { + color: #2A00FF; +} \ No newline at end of file diff --git a/Edgware.SR6/single/css/manual-multipage.css b/Edgware.SR6/single/css/manual-multipage.css new file mode 100644 index 00000000..0c484531 --- /dev/null +++ b/Edgware.SR6/single/css/manual-multipage.css @@ -0,0 +1,9 @@ +@IMPORT url("manual.css"); + +body.firstpage { + background: url("../images/background.png") no-repeat center top; +} + +div.part h1 { + border-top: none; +} diff --git a/Edgware.SR6/single/css/manual-singlepage.css b/Edgware.SR6/single/css/manual-singlepage.css new file mode 100644 index 00000000..4a7fd140 --- /dev/null +++ b/Edgware.SR6/single/css/manual-singlepage.css @@ -0,0 +1,6 @@ +@IMPORT url("manual.css"); + +body { + background: url("../images/background.png") no-repeat center top; +} + diff --git a/Edgware.SR6/single/css/manual.css b/Edgware.SR6/single/css/manual.css new file mode 100644 index 00000000..0ecbe2e8 --- /dev/null +++ b/Edgware.SR6/single/css/manual.css @@ -0,0 +1,344 @@ +@IMPORT url("highlight.css"); + +html { + padding: 0pt; + margin: 0pt; +} + +body { + color: #333333; + margin: 15px 30px; + font-family: Helvetica, Arial, Freesans, Clean, Sans-serif; + line-height: 1.6; + -webkit-font-smoothing: antialiased; +} + +code { + font-size: 16px; + font-family: Consolas, "Liberation Mono", Courier, monospace; +} + +:not(a)>code { + color: #6D180B; +} + +:not(pre)>code { + background-color: #F2F2F2; + border: 1px solid #CCCCCC; + border-radius: 4px; + padding: 1px 3px 0; + text-shadow: none; + white-space: nowrap; +} + +body>*:first-child { + margin-top: 0 !important; +} + +div { + margin: 0pt; +} + +hr { + border: 1px solid #CCCCCC; + background: #CCCCCC; +} + +h1,h2,h3,h4,h5,h6 { + color: #000000; + cursor: text; + font-weight: bold; + margin: 30px 0 10px; + padding: 0; +} + +h1,h2,h3 { + margin: 40px 0 10px; +} + +h1 { + margin: 70px 0 30px; + padding-top: 20px; +} + +div.part h1 { + border-top: 1px dotted #CCCCCC; +} + +h1,h1 code { + font-size: 32px; +} + +h2,h2 code { + font-size: 24px; +} + +h3,h3 code { + font-size: 20px; +} + +h4,h1 code,h5,h5 code,h6,h6 code { + font-size: 18px; +} + +div.book,div.chapter,div.appendix,div.part,div.preface { + min-width: 300px; + max-width: 1200px; + margin: 0 auto; +} + +p.releaseinfo { + font-weight: bold; + margin-bottom: 40px; + margin-top: 40px; +} + +div.authorgroup { + line-height: 1; +} + +p.copyright { + line-height: 1; + margin-bottom: -5px; +} + +.legalnotice p { + font-style: italic; + font-size: 14px; + line-height: 1; +} + +div.titlepage+p,div.titlepage+p { + margin-top: 0; +} + +pre { + line-height: 1.0; + color: black; +} + +a { + color: #4183C4; + text-decoration: none; +} + +p { + margin: 15px 0; + text-align: left; +} + +ul,ol { + padding-left: 30px; +} + +li p { + margin: 0; +} + +div.table { + margin: 1em; + padding: 0.5em; + text-align: center; +} + +div.table table,div.informaltable table { + display: table; + width: 100%; +} + +div.table td { + padding-left: 7px; + padding-right: 7px; +} + +.sidebar { + line-height: 1.4; + padding: 0 20px; + background-color: #F8F8F8; + border: 1px solid #CCCCCC; + border-radius: 3px 3px 3px 3px; +} + +.sidebar p.title { + color: #6D180B; +} + +pre.programlisting,pre.screen { + font-size: 15px; + padding: 6px 10px; + background-color: #F8F8F8; + border: 1px solid #CCCCCC; + border-radius: 3px 3px 3px 3px; + clear: both; + overflow: auto; + line-height: 1.4; + font-family: Consolas, "Liberation Mono", Courier, monospace; +} + +table { + border-collapse: collapse; + border-spacing: 0; + border: 1px solid #DDDDDD !important; + border-radius: 4px !important; + border-collapse: separate !important; + line-height: 1.6; +} + +table thead { + background: #F5F5F5; +} + +table tr { + border: none; + border-bottom: none; +} + +table th { + font-weight: bold; +} + +table th,table td { + border: none !important; + padding: 6px 13px; +} + +table tr:nth-child(2n) { + background-color: #F8F8F8; +} + +td p { + margin: 0 0 15px 0; +} + +div.table-contents td p { + margin: 0; +} + +div.important *,div.note *,div.tip *,div.warning *,div.navheader *,div.navfooter *,div.calloutlist * + { + border: none !important; + background: none !important; + margin: 0; +} + +div.important p,div.note p,div.tip p,div.warning p { + color: #6F6F6F; + line-height: 1.6; +} + +div.important code,div.note code,div.tip code,div.warning code { + background-color: #F2F2F2 !important; + border: 1px solid #CCCCCC !important; + border-radius: 4px !important; + padding: 1px 3px 0 !important; + text-shadow: none !important; + white-space: nowrap !important; +} + +.note th,.tip th,.warning th { + display: none; +} + +.note tr:first-child td,.tip tr:first-child td,.warning tr:first-child td + { + border-right: 1px solid #CCCCCC !important; + padding-top: 10px; +} + +div.calloutlist p,div.calloutlist td { + padding: 0; + margin: 0; +} + +div.calloutlist>table>tbody>tr>td:first-child { + padding-left: 10px; + width: 30px !important; +} + +div.important,div.note,div.tip,div.warning { + margin-left: 0px !important; + margin-right: 20px !important; + margin-top: 20px; + margin-bottom: 20px; + padding-top: 10px; + padding-bottom: 10px; +} + +div.toc { + line-height: 1.2; +} + +dl,dt { + margin-top: 1px; + margin-bottom: 0; +} + +div.toc>dl>dt { + font-size: 32px; + font-weight: bold; + margin: 30px 0 10px 0; + display: block; +} + +div.toc>dl>dd>dl>dt { + font-size: 24px; + font-weight: bold; + margin: 20px 0 10px 0; + display: block; +} + +div.toc>dl>dd>dl>dd>dl>dt { + font-weight: bold; + font-size: 20px; + margin: 10px 0 0 0; +} + +tbody.footnotes * { + border: none !important; +} + +div.footnote p { + margin: 0; + line-height: 1; +} + +div.footnote p sup { + margin-right: 6px; + vertical-align: middle; +} + +div.navheader { + border-bottom: 1px solid #CCCCCC; +} + +div.navfooter { + border-top: 1px solid #CCCCCC; +} + +.title { + margin-left: -1em; + padding-left: 1em; +} + +.title>a { + position: absolute; + visibility: hidden; + display: block; + font-size: 0.85em; + margin-top: 0.05em; + margin-left: -1em; + vertical-align: text-top; + color: black; +} + +.title>a:before { + content: "\00A7"; +} + +.title:hover>a,.title>a:hover,.title:hover>a:hover { + visibility: visible; +} + +.title:focus>a,.title>a:focus,.title:focus>a:focus { + outline: 0; +} diff --git a/Edgware.SR6/single/images/background.png b/Edgware.SR6/single/images/background.png new file mode 100644 index 00000000..15dca6fb Binary files /dev/null and b/Edgware.SR6/single/images/background.png differ diff --git a/Edgware.SR6/single/images/caution.png b/Edgware.SR6/single/images/caution.png new file mode 100644 index 00000000..8a5e4fca Binary files /dev/null and b/Edgware.SR6/single/images/caution.png differ diff --git a/Edgware.SR6/single/images/important.png b/Edgware.SR6/single/images/important.png new file mode 100644 index 00000000..ec54df65 Binary files /dev/null and b/Edgware.SR6/single/images/important.png differ diff --git a/Edgware.SR6/single/images/logo.png b/Edgware.SR6/single/images/logo.png new file mode 100644 index 00000000..ade2ce6e Binary files /dev/null and b/Edgware.SR6/single/images/logo.png differ diff --git a/Edgware.SR6/single/images/note.png b/Edgware.SR6/single/images/note.png new file mode 100644 index 00000000..88d997b1 Binary files /dev/null and b/Edgware.SR6/single/images/note.png differ diff --git a/Edgware.SR6/single/images/sts_exception.png b/Edgware.SR6/single/images/sts_exception.png new file mode 100644 index 00000000..8607c38a Binary files /dev/null and b/Edgware.SR6/single/images/sts_exception.png differ diff --git a/Edgware.SR6/single/images/tip.png b/Edgware.SR6/single/images/tip.png new file mode 100644 index 00000000..6530abb4 Binary files /dev/null and b/Edgware.SR6/single/images/tip.png differ diff --git a/Edgware.SR6/single/images/warning.png b/Edgware.SR6/single/images/warning.png new file mode 100644 index 00000000..0d5b5244 Binary files /dev/null and b/Edgware.SR6/single/images/warning.png differ diff --git a/Edgware.SR6/single/images/web-selected.png b/Edgware.SR6/single/images/web-selected.png new file mode 100644 index 00000000..aa6b2da6 Binary files /dev/null and b/Edgware.SR6/single/images/web-selected.png differ diff --git a/Edgware.SR6/single/spring-cloud.html b/Edgware.SR6/single/spring-cloud.html new file mode 100644 index 00000000..df6fbe1d --- /dev/null +++ b/Edgware.SR6/single/spring-cloud.html @@ -0,0 +1,11953 @@ + + + Spring Cloud

Spring Cloud

Table of Contents

1. Features
I. Cloud Native Applications
2. Spring Cloud Context: Application Context Services
2.1. The Bootstrap Application Context
2.2. Application Context Hierarchies
2.3. Changing the Location of Bootstrap Properties
2.4. Overriding the Values of Remote Properties
2.5. Customizing the Bootstrap Configuration
2.6. Customizing the Bootstrap Property Sources
2.7. Logging Configuration
2.8. Environment Changes
2.9. Refresh Scope
2.10. Encryption and Decryption
2.11. Endpoints
3. Spring Cloud Commons: Common Abstractions
3.1. @EnableDiscoveryClient
3.1.1. Health Indicator
3.2. ServiceRegistry
3.2.1. ServiceRegistry Auto-Registration
3.2.2. Service Registry Actuator Endpoint
3.3. Spring RestTemplate as a Load Balancer Client
3.3.1. Retrying Failed Requests
3.4. Multiple RestTemplate objects
3.5. Ignore Network Interfaces
3.6. HTTP Client Factories
3.7. Spring Cloud Compatibility Verification
II. Spring Cloud Config
4. Quick Start
4.1. Client Side Usage
5. Spring Cloud Config Server
5.1. Environment Repository
5.1.1. Git Backend
Placeholders in Git URI
Pattern Matching and Multiple Repositories
Authentication
Authentication with AWS CodeCommit
Git SSH configuration using properties
Placeholders in Git Search Paths
Force pull in Git Repositories
Deleting untracked branches in Git Repositories
5.1.2. Version Control Backend Filesystem Use
5.1.3. File System Backend
5.1.4. Vault Backend
Multiple Properties Sources
5.1.5. Sharing Configuration With All Applications
File Based Repositories
Vault Server
5.1.6. JDBC Backend
5.1.7. Composite Environment Repositories
Custom Composite Environment Repositories
5.1.8. Property Overrides
5.2. Health Indicator
5.3. Security
5.4. Encryption and Decryption
5.5. Key Management
5.6. Creating a Key Store for Testing
5.7. Using Multiple Keys and Key Rotation
5.8. Serving Encrypted Properties
6. Serving Alternative Formats
7. Serving Plain Text
8. Embedding the Config Server
9. Push Notifications and Spring Cloud Bus
10. Spring Cloud Config Client
10.1. Config First Bootstrap
10.2. Discovery First Bootstrap
10.3. Config Client Fail Fast
10.4. Config Client Retry
10.5. Locating Remote Configuration Resources
10.6. Security
10.6.1. Health Indicator
10.6.2. Providing A Custom RestTemplate
10.6.3. Vault
10.7. Vault
10.7.1. Nested Keys In Vault
III. Spring Cloud Netflix
11. Service Discovery: Eureka Clients
11.1. How to Include Eureka Client
11.2. Registering with Eureka
11.3. Authenticating with the Eureka Server
11.4. Status Page and Health Indicator
11.5. Registering a Secure Application
11.6. Eureka’s Health Checks
11.7. Eureka Metadata for Instances and Clients
11.7.1. Using Eureka on Cloud Foundry
11.7.2. Using Eureka on AWS
11.7.3. Changing the Eureka Instance ID
11.8. Using the EurekaClient
11.8.1. EurekaClient without Jersey
11.9. Alternatives to the native Netflix EurekaClient
11.10. Why is it so Slow to Register a Service?
11.11. Zones
12. Service Discovery: Eureka Server
12.1. How to Include Eureka Server
12.2. How to Run a Eureka Server
12.3. High Availability, Zones and Regions
12.4. Standalone Mode
12.5. Peer Awareness
12.6. Prefer IP Address
13. Circuit Breaker: Hystrix Clients
13.1. How to Include Hystrix
13.2. Propagating the Security Context or using Spring Scopes
13.3. Health Indicator
13.4. Hystrix Metrics Stream
14. Circuit Breaker: Hystrix Dashboard
15. Hystrix Timeouts And Ribbon Clients
15.1. How to Include Hystrix Dashboard
15.2. Turbine
15.3. Turbine Stream
16. Client Side Load Balancer: Ribbon
16.1. How to Include Ribbon
16.2. Customizing the Ribbon Client
16.3. Customizing default for all Ribbon Clients
16.4. Customizing the Ribbon Client using properties
16.5. Using Ribbon with Eureka
16.6. Example: How to Use Ribbon Without Eureka
16.7. Example: Disable Eureka use in Ribbon
16.8. Using the Ribbon API Directly
16.9. Caching of Ribbon Configuration
16.10. How to Configure Hystrix thread pools
16.11. How to Provide a Key to Ribbon’s IRule
17. Declarative REST Client: Feign
17.1. How to Include Feign
17.2. Overriding Feign Defaults
17.3. Creating Feign Clients Manually
17.4. Feign Hystrix Support
17.5. Feign Hystrix Fallbacks
17.6. Feign and @Primary
17.7. Feign Inheritance Support
17.8. Feign request/response compression
17.9. Feign logging
18. External Configuration: Archaius
19. Router and Filter: Zuul
19.1. How to Include Zuul
19.2. Embedded Zuul Reverse Proxy
19.3. Zuul Http Client
19.4. Cookies and Sensitive Headers
19.5. Ignored Headers
19.6. Management Endpoints
19.6.1. Routes Endpoint
19.6.2. Filters Endpoint
19.7. Strangulation Patterns and Local Forwards
19.8. Uploading Files through Zuul
19.9. Query String Encoding
19.10. Plain Embedded Zuul
19.11. Disable Zuul Filters
19.12. Providing Hystrix Fallbacks For Routes
19.13. Zuul Timeouts
19.13.1. Service Discovery Configuration
19.13.2. URL Configuration
19.14. Rewriting Location header
19.15. Zuul Developer Guide
19.15.1. The Zuul Servlet
19.15.2. Zuul RequestContext
19.15.3. @EnableZuulProxy vs. @EnableZuulServer
19.15.4. @EnableZuulServer Filters
19.15.5. @EnableZuulProxy Filters
19.15.6. Custom Zuul Filter examples
19.15.7. How to Write a Pre Filter
19.15.8. How to Write a Route Filter
19.15.9. How to Write a Post Filter
19.15.10. How Zuul Errors Work
19.15.11. Zuul Eager Application Context Loading
20. Polyglot support with Sidecar
21. RxJava with Spring MVC
22. Metrics: Spectator, Servo, and Atlas
22.1. Dimensional vs. Hierarchical Metrics
22.2. Default Metrics Collection
22.3. Metrics Collection: Spectator
22.3.1. Spectator Counter
22.3.2. Spectator Timer
22.3.3. Spectator Gauge
22.3.4. Spectator Distribution Summaries
22.4. Metrics Collection: Servo
22.4.1. Creating Servo Monitors
22.5. Metrics Backend: Atlas
22.5.1. Global tags
22.5.2. Using Atlas
22.6. Retrying Failed Requests
22.6.1. BackOff Policies
22.6.2. Configuration
22.6.3. Zuul
23. HTTP Clients
IV. Spring Cloud Stream
24. Introducing Spring Cloud Stream
25. Main Concepts
25.1. Application Model
25.1.1. Fat JAR
25.2. The Binder Abstraction
25.3. Persistent Publish-Subscribe Support
25.4. Consumer Groups
25.4.1. Durability
25.5. Partitioning Support
26. Programming Model
26.1. Declaring and Binding Channels
26.1.1. Triggering Binding Via @EnableBinding
26.1.2. @Input and @Output
Customizing Channel Names
Source, Sink, and Processor
26.1.3. Accessing Bound Channels
Injecting the Bound Interfaces
Injecting Channels Directly
26.1.4. Producing and Consuming Messages
Native Spring Integration Support
Spring Integration Error Channel Support
Message Channel Binders and Error Channels
Using @StreamListener for Automatic Content Type Handling
Using @StreamListener for dispatching messages to multiple methods
26.1.5. Reactive Programming Support
Reactor-based handlers
RxJava 1.x support
Reactive Sources
26.1.6. Aggregation
Configuring aggregate application
Configuring binding service properties for non self contained aggregate application
27. Binders
27.1. Producers and Consumers
27.2. Binder SPI
27.3. Binder Detection
27.3.1. Classpath Detection
27.4. Multiple Binders on the Classpath
27.5. Connecting to Multiple Systems
27.6. Binder configuration properties
28. Configuration Options
28.1. Spring Cloud Stream Properties
28.2. Binding Properties
28.2.1. Properties for Use of Spring Cloud Stream
28.2.2. Consumer properties
28.2.3. Producer Properties
28.3. Using dynamically bound destinations
29. Content Type and Transformation
29.1. MIME types
29.2. MIME types and Java types
29.3. Customizing message conversion
29.4. @StreamListener and Message Conversion
30. Schema Evolution Support
30.1. Schema Registry Client
30.1.1. Schema Registry Client Properties
30.2. Avro Schema Registry Client Message Converters
30.2.1. Avro Schema Registry Message Converter Properties
30.3. Apache Avro Message Converters
30.4. Converters with Schema Support
30.5. Schema Registry Server
30.5.1. Schema Registry Server API
Registering a New Schema
Retrieving an Existing Schema by Subject, Format, and Version
Retrieving an Existing Schema by Subject and Format
Retrieving an Existing Schema by ID
Deleting a Schema by Subject, Format, and Version
Deleting a Schema by ID
Deleting a Schema by Subject
30.5.2. Using Confluent’s Schema Registry
30.6. Schema Registration and Resolution
30.6.1. Schema Registration Process (Serialization)
30.6.2. Schema Resolution Process (Deserialization)
31. Inter-Application Communication
31.1. Connecting Multiple Application Instances
31.2. Instance Index and Instance Count
31.3. Partitioning
31.3.1. Configuring Output Bindings for Partitioning
Spring-managed custom PartitionKeyExtractorClass implementations
Configuring Input Bindings for Partitioning
32. Testing
32.1. Disabling the test binder autoconfiguration
33. Health Indicator
34. Metrics Emitter
35. Samples
36. Getting Started
36.1. Deploying Stream applications on CloudFoundry
V. Binder Implementations
37. Apache Kafka Binder
37.1. Usage
37.2. Apache Kafka Binder Overview
37.3. Configuration Options
37.3.1. Kafka Binder Properties
37.3.2. Kafka Consumer Properties
37.3.3. Kafka Producer Properties
37.3.4. Usage examples
Example: Setting autoCommitOffset false and relying on manual acking.
Example: security configuration
Using the binder with Apache Kafka 0.10
Excluding Kafka broker jar from the classpath of the binder based application
37.4. Kafka Streams Binding Capabilities of Spring Cloud Stream
37.4.1. Usage example of high level streams DSL
37.4.2. Support for interactive queries
37.4.3. Kafka Streams properties
37.5. Error Channels
37.6. Kafka Metrics
37.7. Dead-Letter Topic Processing
38. RabbitMQ Binder
38.1. Usage
38.2. RabbitMQ Binder Overview
38.3. Configuration Options
38.3.1. RabbitMQ Binder Properties
38.3.2. RabbitMQ Consumer Properties
38.3.3. Rabbit Producer Properties
38.4. Retry With the RabbitMQ Binder
38.4.1. Overview
38.4.2. Putting it All Together
38.5. Error Channels
38.6. Dead-Letter Queue Processing
38.6.1. Non-Partitioned Destinations
38.6.2. Partitioned Destinations
republishToDlq=false
republishToDlq=true
VI. Spring Cloud Bus
39. Quick Start
40. Addressing an Instance
41. Addressing all instances of a service
42. Application Context ID must be unique
43. Customizing the Message Broker
44. Tracing Bus Events
45. Broadcasting Your Own Events
45.1. Registering events in custom packages
VII. Spring Cloud Sleuth
46. Introduction
46.1. Terminology
46.2. Purpose
46.2.1. Distributed tracing with Zipkin
46.2.2. Visualizing errors
46.2.3. Live examples
46.2.4. Log correlation
JSON Logback with Logstash
46.2.5. Propagating Span Context
Baggage vs. Span Tags
46.3. Adding to the project
46.3.1. Only Sleuth (log correlation)
46.3.2. Sleuth with Zipkin via HTTP
46.3.3. Sleuth with Zipkin via RabbitMQ or Kafka
47. Additional resources
48. Features
49. Sampling
50. Instrumentation
51. Span lifecycle
51.1. Creating and closing spans
51.2. Continuing spans
51.3. Creating spans with an explicit parent
52. Naming spans
52.1. @SpanName annotation
52.2. toString() method
53. Managing spans with annotations
53.1. Rationale
53.2. Creating new spans
53.3. Continuing spans
53.4. More advanced tag setting
53.4.1. Custom extractor
53.4.2. Resolving expressions for value
53.4.3. Using toString method
54. Customizations
54.1. Spring Integration
54.2. HTTP
54.3. Example
54.4. TraceFilter
54.5. Custom SA tag in Zipkin
54.6. Custom service name
54.7. Customization of reported spans
54.8. Host locator
55. Sending spans to Zipkin
56. Span Data as Messages
56.1. Zipkin Consumer
56.2. Custom Consumer
57. Metrics
58. Integrations
58.1. Runnable and Callable
58.2. Hystrix
58.2.1. Custom Concurrency Strategy
58.2.2. Manual Command setting
58.3. RxJava
58.4. HTTP integration
58.4.1. HTTP Filter
58.4.2. HandlerInterceptor
58.4.3. Async Servlet support
58.5. HTTP client integration
58.5.1. Synchronous Rest Template
58.5.2. Asynchronous Rest Template
Multiple Asynchronous Rest Templates
58.5.3. Traverson
58.6. Feign
58.7. Asynchronous communication
58.7.1. @Async annotated methods
58.7.2. @Scheduled annotated methods
58.7.3. Executor, ExecutorService and ScheduledExecutorService
Customization of Executors
58.8. Messaging
58.9. Zuul
58.10. Spring Cloud Function
59. Running examples
VIII. Spring Cloud Consul
60. Install Consul
61. Consul Agent
62. Service Discovery with Consul
62.1. How to activate
62.2. Registering with Consul
62.3. HTTP Health Check
62.3.1. Metadata and Consul tags
62.3.2. Making the Consul Instance ID Unique
62.4. Looking up services
62.4.1. Using Ribbon
62.4.2. Using the DiscoveryClient
63. Distributed Configuration with Consul
63.1. How to activate
63.2. Customizing
63.3. Config Watch
63.4. YAML or Properties with Config
63.5. git2consul with Config
63.6. Fail Fast
64. Consul Retry
65. Spring Cloud Bus with Consul
65.1. How to activate
66. Circuit Breaker with Hystrix
67. Hystrix metrics aggregation with Turbine and Consul
IX. Spring Cloud Zookeeper
68. Install Zookeeper
69. Service Discovery with Zookeeper
69.1. How to activate
69.2. Registering with Zookeeper
69.3. Using the DiscoveryClient
70. Using Spring Cloud Zookeeper with Spring Cloud Netflix Components
70.1. Ribbon with Zookeeper
71. Spring Cloud Zookeeper and Service Registry
71.1. Instance Status
72. Zookeeper Dependencies
72.1. Using the Zookeeper Dependencies
72.2. How to activate Zookeeper Dependencies
72.3. Setting up Zookeeper Dependencies
72.3.1. Aliases
72.3.2. Path
72.3.3. Load balancer type
72.3.4. Content-Type template and version
72.3.5. Default headers
72.3.6. Obligatory dependencies
72.3.7. Stubs
72.4. Configuring Spring Cloud Zookeeper Dependencies
73. Spring Cloud Zookeeper Dependency Watcher
73.1. How to activate
73.2. Registering a listener
73.3. Presence Checker
74. Distributed Configuration with Zookeeper
74.1. How to activate
74.2. Customizing
74.3. ACLs
X. Spring Boot Cloud CLI
75. Installation
76. Running Spring Cloud Services in Development
76.1. Adding Additional Applications
77. Writing Groovy Scripts and Running Applications
78. Encryption and Decryption
XI. Spring Cloud Security
79. Quickstart
79.1. OAuth2 Single Sign On
79.2. OAuth2 Protected Resource
80. More Detail
80.1. Single Sign On
80.2. Token Relay
80.2.1. Client Token Relay
80.2.2. Client Token Relay in Zuul Proxy
80.2.3. Resource Server Token Relay
81. Configuring Authentication Downstream of a Zuul Proxy
XII. Spring Cloud for Cloud Foundry
82. Discovery
83. Single Sign On
XIII. Spring Cloud Contract
84. Spring Cloud Contract
85. Spring Cloud Contract Verifier Introduction
85.1. Why a Contract Verifier?
85.1.1. Testing issues
85.2. Purposes
85.3. How It Works
85.3.1. Defining the contract
85.3.2. Client Side
85.3.3. Server Side
85.4. Step-by-step Guide to Consumer Driven Contracts (CDC)
85.4.1. Technical note
85.4.2. Consumer side (Loan Issuance)
85.4.3. Producer side (Fraud Detection server)
85.4.4. Consumer Side (Loan Issuance) Final Step
85.5. Dependencies
85.6. Additional Links
85.6.1. Spring Cloud Contract video
85.6.2. Readings
85.7. Samples
86. Spring Cloud Contract FAQ
86.1. Why use Spring Cloud Contract Verifier and not X ?
86.2. I don’t want to write a contract in Groovy!
86.3. What is this value(consumer(), producer()) ?
86.4. How to do Stubs versioning?
86.4.1. API Versioning
86.4.2. JAR versioning
86.4.3. Dev or prod stubs
86.5. Common repo with contracts
86.5.1. Repo structure
86.5.2. Workflow
86.5.3. Consumer
86.5.4. Producer
86.6. Can I have multiple base classes for tests?
86.7. How can I debug the request/response being sent by the generated tests client?
86.7.1. How can I debug the mapping/request/response being sent by WireMock?
86.7.2. How can I see what got registered in the HTTP server stub?
86.7.3. Can I reference the request from the response?
86.7.4. Can I reference text from file?
87. Spring Cloud Contract Verifier Setup
87.1. Gradle Project
87.1.1. Prerequisites
87.1.2. Add Gradle Plugin with Dependencies
87.1.3. Gradle and Rest Assured 2.0
87.1.4. Snapshot Versions for Gradle
87.1.5. Add stubs
87.1.6. Run the Plugin
87.1.7. Default Setup
87.1.8. Configure Plugin
87.1.9. Configuration Options
87.1.10. Single Base Class for All Tests
87.1.11. Different Base Classes for Contracts
87.1.12. Invoking Generated Tests
87.1.13. Spring Cloud Contract Verifier on the Consumer Side
87.2. Maven Project
87.2.1. Add maven plugin
87.2.2. Maven and Rest Assured 2.0
87.2.3. Snapshot versions for Maven
87.2.4. Add stubs
87.2.5. Run plugin
87.2.6. Configure plugin
87.2.7. Configuration Options
87.2.8. Single Base Class for All Tests
87.2.9. Different base classes for contracts
87.2.10. Invoking generated tests
87.2.11. Maven Plugin and STS
87.3. Stubs and Transitive Dependencies
87.4. CI Server setup
87.5. Scenarios
87.6. Docker Project
87.6.1. Short intro to Maven, JARs and Binary storage
87.6.2. How it works
Environment Variables
87.6.3. Example of usage
87.6.4. Server side (nodejs)
88. Spring Cloud Contract Verifier Messaging
88.1. Integrations
88.2. Manual Integration Testing
88.3. Publisher-Side Test Generation
88.3.1. Scenario 1: No Input Message
88.3.2. Scenario 2: Output Triggered by Input
88.3.3. Scenario 3: No Output Message
88.4. Consumer Stub Generation
89. Spring Cloud Contract Stub Runner
89.1. Snapshot versions
89.2. Publishing Stubs as JARs
89.3. Stub Runner Core
89.3.1. Retrieving stubs
Stub downloading
Classpath scanning
89.3.2. Running stubs
Running using main app
HTTP Stubs
Viewing registered mappings
Messaging Stubs
89.4. Stub Runner JUnit Rule
89.4.1. Maven settings
89.4.2. Providing fixed ports
89.4.3. Fluent API
89.4.4. Stub Runner with Spring
89.5. Stub Runner Spring Cloud
89.5.1. Stubbing Service Discovery
Test profiles and service discovery
89.5.2. Additional Configuration
89.6. Stub Runner Boot Application
89.6.1. How to use it?
Stub Runner Server
Stub Runner Server Fat Jar
Spring Cloud CLI
89.6.2. Endpoints
HTTP
Messaging
89.6.3. Example
89.6.4. Stub Runner Boot with Service Discovery
89.7. Stubs Per Consumer
89.8. Common
89.8.1. Common Properties for JUnit and Spring
89.8.2. Stub Runner Stubs IDs
89.9. Stub Runner Docker
89.9.1. How to use it
89.9.2. Example of client side usage in a non JVM project
90. Stub Runner for Messaging
90.1. Stub triggering
90.1.1. Trigger by Label
90.1.2. Trigger by Group and Artifact Ids
90.1.3. Trigger by Artifact Ids
90.1.4. Trigger All Messages
90.2. Stub Runner Camel
90.2.1. Adding the Runner to the Project
90.2.2. Disabling the functionality
Scenario 1 (no input message)
Scenario 2 (output triggered by input)
Scenario 3 (input with no output)
90.3. Stub Runner Integration
90.3.1. Adding the Runner to the Project
90.3.2. Disabling the functionality
Scenario 1 (no input message)
Scenario 2 (output triggered by input)
Scenario 3 (input with no output)
90.4. Stub Runner Stream
90.4.1. Adding the Runner to the Project
90.4.2. Disabling the functionality
Scenario 1 (no input message)
Scenario 2 (output triggered by input)
Scenario 3 (input with no output)
90.5. Stub Runner Spring AMQP
90.5.1. Adding the Runner to the Project
Triggering the message
Spring AMQP Test Configuration
91. Contract DSL
91.1. Limitations
91.2. Common Top-Level elements
91.2.1. Description
91.2.2. Name
91.2.3. Ignoring Contracts
91.2.4. Passing Values from Files
91.2.5. HTTP Top-Level Elements
91.3. Request
91.4. Response
91.5. Dynamic properties
91.5.1. Dynamic properties inside the body
91.5.2. Regular expressions
91.5.3. Passing Optional Parameters
91.5.4. Executing Custom Methods on the Server Side
91.5.5. Referencing the Request from the Response
91.5.6. Registering Your Own WireMock Extension
91.5.7. Dynamic Properties in the Matchers Sections
91.6. JAX-RS Support
91.7. Async Support
91.8. Working with Context Paths
91.9. Messaging Top-Level Elements
91.9.1. Output Triggered by a Method
91.9.2. Output Triggered by a Message
91.9.3. Consumer/Producer
91.9.4. Common
91.10. Multiple Contracts in One File
92. Customization
92.1. Extending the DSL
92.1.1. Common JAR
92.1.2. Adding the Dependency to the Project
92.1.3. Test the Dependency in the Project’s Dependencies
92.1.4. Test a Dependency in the Plugin’s Dependencies
92.1.5. Referencing classes in DSLs
93. Using the Pluggable Architecture
93.1. Custom Contract Converter
93.1.1. Pact Converter
93.1.2. Pact Contract
93.1.3. Pact for Producers
93.1.4. Pact for Consumers
93.2. Using the Custom Test Generator
93.3. Using the Custom Stub Generator
93.4. Using the Custom Stub Runner
93.5. Using the Custom Stub Downloader
94. Spring Cloud Contract WireMock
94.1. Registering Stubs Automatically
94.2. Using Files to Specify the Stub Bodies
94.3. Alternative: Using JUnit Rules
94.4. Relaxed SSL Validation for Rest Template
94.5. WireMock and Spring MVC Mocks
94.6. Customization of WireMock configuration
94.7. Generating Stubs using REST Docs
94.8. Generating Contracts by Using REST Docs
95. Migrations
95.1. 1.0.x → 1.1.x
95.1.1. New structure of generated stubs
95.2. 1.1.x → 1.2.x
95.2.1. Custom HttpServerStub
95.2.2. New packages for generated tests
95.2.3. New Methods in TemplateProcessor
95.2.4. RestAssured 3.0
96. Links
XIV. Spring Cloud Vault
97. Quick Start
98. Client Side Usage
98.1. Authentication
99. Authentication methods
99.1. Token authentication
99.2. AppId authentication
99.2.1. Custom UserId
99.3. AppRole authentication
99.4. AWS-EC2 authentication
99.5. AWS-IAM authentication
99.6. TLS certificate authentication
99.7. Cubbyhole authentication
99.8. Kubernetes authentication
100. Secret Backends
100.1. Generic Backend
100.2. Consul
100.3. RabbitMQ
100.4. AWS
101. Database backends
101.1. Apache Cassandra
101.2. MongoDB
101.3. MySQL
101.4. PostgreSQL
102. Configure PropertySourceLocator behavior
103. Service Registry Configuration
104. Vault Client Fail Fast
105. Vault Client SSL configuration
106. Lease lifecycle management (renewal and revocation)
XV. Spring Cloud Function
107. Introduction
108. Getting Started
109. Building and Running a Function
110. Function Catalog and Flexible Function Signatures
111. Standalone Web Applications
112. Standalone Streaming Applications
113. Deploying a Packaged Function
114. Dynamic Compilation
115. Serverless Platform Adapters
115.1. AWS Lambda
115.1.1. Introduction
115.1.2. Notes on JAR Layout
115.1.3. Upload
115.1.4. Platfom Specific Features
HTTP and API Gateway
115.2. Azure Functions
115.2.1. Notes on JAR Layout
115.2.2. JSON Configuration
115.2.3. Build
115.2.4. Running the sample
115.3. Apache Openwhisk
115.3.1. Quick Start
XVI. Appendix: Compendium of Configuration Properties

Spring Cloud provides tools for developers to quickly build some of +the common patterns in distributed systems (e.g. configuration +management, service discovery, circuit breakers, intelligent routing, +micro-proxy, control bus). Coordination of +distributed systems leads to boiler plate patterns, and using Spring +Cloud developers can quickly stand up services and applications that +implement those patterns. They will work well in any distributed +environment, including the developer’s own laptop, bare metal data +centres, and managed platforms such as Cloud Foundry.

Version: 1.3.8.RELEASE

1. Features

Spring Cloud focuses on providing good out of box experience for typical use cases +and extensibility mechanism to cover others.

  • Distributed/versioned configuration
  • Service registration and discovery
  • Routing
  • Service-to-service calls
  • Load balancing
  • Circuit Breakers
  • Distributed messaging

Part I. Cloud Native Applications

Cloud Native is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development. A related discipline is that of building 12-factor Apps in which development practices are aligned with delivery and operations goals, for instance by using declarative programming and management and monitoring. Spring Cloud facilitates these styles of development in a number of specific ways and the starting point is a set of features that all components in a distributed system either need or need easy access to when required.

Many of those features are covered by Spring Boot, which we build on in Spring Cloud. Some more are delivered by Spring Cloud as two libraries: Spring Cloud Context and Spring Cloud Commons. Spring Cloud Context provides utilities and special services for the ApplicationContext of a Spring Cloud application (bootstrap context, encryption, refresh scope and environment endpoints). Spring Cloud Commons is a set of abstractions and common classes used in different Spring Cloud implementations (eg. Spring Cloud Netflix vs. Spring Cloud Consul).

If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:

Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

2. Spring Cloud Context: Application Context Services

Spring Boot has an opinionated view of how to build an application +with Spring: for instance it has conventional locations for common +configuration file, and endpoints for common management and monitoring +tasks. Spring Cloud builds on top of that and adds a few features that +probably all components in a system would use or occasionally need.

2.1 The Bootstrap Application Context

A Spring Cloud application operates by creating a "bootstrap" +context, which is a parent context for the main application. Out of +the box it is responsible for loading configuration properties from +the external sources, and also decrypting properties in the local +external configuration files. The two contexts share an Environment +which is the source of external properties for any Spring +application. Bootstrap properties (not bootstrap.properties but properties + that are loaded during the bootstrap phase) are added with high precedence, so +they cannot be overridden by local configuration, by default.

The bootstrap context uses a different convention for locating +external configuration than the main application context, so instead +of application.yml (or .properties) you use bootstrap.yml, +keeping the external configuration for bootstrap and main context +nicely separate. Example:

bootstrap.yml.  +

spring:
+  application:
+    name: foo
+  cloud:
+    config:
+      uri: ${SPRING_CONFIG_URI:http://localhost:8888}

+

It is a good idea to set the spring.application.name (in +bootstrap.yml or application.yml) if your application needs any +application-specific configuration from the server.

You can disable the bootstrap process completely by setting +spring.cloud.bootstrap.enabled=false (e.g. in System properties).

2.2 Application Context Hierarchies

If you build an application context from SpringApplication or +SpringApplicationBuilder, then the Bootstrap context is added as a +parent to that context. It is a feature of Spring that child contexts +inherit property sources and profiles from their parent, so the "main" +application context will contain additional property sources, compared +to building the same context without Spring Cloud Config. The +additional property sources are:

  • "bootstrap": an optional CompositePropertySource appears with high +priority if any PropertySourceLocators are found in the Bootstrap +context, and they have non-empty properties. An example would be +properties from the Spring Cloud Config Server. See +below for instructions +on how to customize the contents of this property source.
  • "applicationConfig: [classpath:bootstrap.yml]" (and friends if +Spring profiles are active). If you have a bootstrap.yml (or +properties) then those properties are used to configure the Bootstrap +context, and then they get added to the child context when its parent +is set. They have lower precedence than the application.yml (or +properties) and any other property sources that are added to the child +as a normal part of the process of creating a Spring Boot +application. See below for +instructions on how to customize the contents of these property +sources.

Because of the ordering rules of property sources the "bootstrap" +entries take precedence, but note that these do not contain any data +from bootstrap.yml, which has very low precedence, but can be used +to set defaults.

You can extend the context hierarchy by simply setting the parent +context of any ApplicationContext you create, e.g. using its own +interface, or with the SpringApplicationBuilder convenience methods +(parent(), child() and sibling()). The bootstrap context will be +the parent of the most senior ancestor that you create yourself. +Every context in the hierarchy will have its own "bootstrap" property +source (possibly empty) to avoid promoting values inadvertently from +parents down to their descendants. Every context in the hierarchy can +also (in principle) have a different spring.application.name and +hence a different remote property source if there is a Config +Server. Normal Spring application context behaviour rules apply to +property resolution: properties from a child context override those in +the parent, by name and also by property source name (if the child has +a property source with the same name as the parent, the one from the +parent is not included in the child).

Note that the SpringApplicationBuilder allows you to share an +Environment amongst the whole hierarchy, but that is not the +default. Thus, sibling contexts in particular do not need to have the +same profiles or property sources, even though they will share common +things with their parent.

2.3 Changing the Location of Bootstrap Properties

The bootstrap.yml (or .properties) location can be specified using +spring.cloud.bootstrap.name (default "bootstrap") or +spring.cloud.bootstrap.location (default empty), e.g. in System +properties. Those properties behave like the spring.config.* +variants with the same name, in fact they are used to set up the +bootstrap ApplicationContext by setting those properties in its +Environment. If there is an active profile (from +spring.profiles.active or through the Environment API in the +context you are building) then properties in that profile will be +loaded as well, just like in a regular Spring Boot app, e.g. from +bootstrap-development.properties for a "development" profile.

2.4 Overriding the Values of Remote Properties

The property sources that are added to you application by the +bootstrap context are often "remote" (e.g. from a Config Server), and +by default they cannot be overridden locally, except on the command +line. If you want to allow your applications to override the remote +properties with their own System properties or config files, the +remote property source has to grant it permission by setting +spring.cloud.config.allowOverride=true (it doesn’t work to set this +locally). Once that flag is set there are some finer grained settings +to control the location of the remote properties in relation to System +properties and the application’s local configuration: +spring.cloud.config.overrideNone=true to override with any local +property source, and +spring.cloud.config.overrideSystemProperties=false if only System +properties and env vars should override the remote settings, but not +the local config files.

2.5 Customizing the Bootstrap Configuration

The bootstrap context can be trained to do anything you like by adding +entries to /META-INF/spring.factories under the key +org.springframework.cloud.bootstrap.BootstrapConfiguration. This is +a comma-separated list of Spring @Configuration classes which will +be used to create the context. Any beans that you want to be available +to the main application context for autowiring can be created here, +and also there is a special contract for @Beans of type +ApplicationContextInitializer. Classes can be marked with an @Order +if you want to control the startup sequence (the default order is +"last").

[Warning]Warning

Be careful when adding custom BootstrapConfiguration that the +classes you add are not @ComponentScanned by mistake into your +"main" application context, where they might not be needed. +Use a separate package name for boot configuration classes that is +not already covered by your @ComponentScan or @SpringBootApplication +annotated configuration classes.

The bootstrap process ends by injecting initializers into the main +SpringApplication instance (i.e. the normal Spring Boot startup +sequence, whether it is running as a standalone app or deployed in an +application server). First a bootstrap context is created from the +classes found in spring.factories and then all @Beans of type +ApplicationContextInitializer are added to the main +SpringApplication before it is started.

2.6 Customizing the Bootstrap Property Sources

The default property source for external configuration added by the +bootstrap process is the Config Server, but you can add additional +sources by adding beans of type PropertySourceLocator to the +bootstrap context (via spring.factories). You could use this to +insert additional properties from a different server, or from a +database, for instance.

As an example, consider the following trivial custom locator:

@Configuration
+public class CustomPropertySourceLocator implements PropertySourceLocator {
+
+    @Override
+    public PropertySource<?> locate(Environment environment) {
+        return new MapPropertySource("customProperty",
+                Collections.<String, Object>singletonMap("property.from.sample.custom.source", "worked as intended"));
+    }
+
+}

The Environment that is passed in is the one for the +ApplicationContext about to be created, i.e. the one that we are +supplying additional property sources for. It will already have its +normal Spring Boot-provided property sources, so you can use those to +locate a property source specific to this Environment (e.g. by +keying it on the spring.application.name, as is done in the default +Config Server property source locator).

If you create a jar with this class in it and then add a +META-INF/spring.factories containing:

org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator

then the "customProperty" PropertySource will show up in any +application that includes that jar on its classpath.

2.7 Logging Configuration

If you are going to use Spring Boot to configure log settings than +you should place this configuration in `bootstrap.[yml | properties] +if you would like it to apply to all events.

2.8 Environment Changes

The application will listen for an EnvironmentChangeEvent and react +to the change in a couple of standard ways (additional +ApplicationListeners can be added as @Beans by the user in the +normal way). When an EnvironmentChangeEvent is observed it will +have a list of key values that have changed, and the application will +use those to:

  • Re-bind any @ConfigurationProperties beans in the context
  • Set the logger levels for any properties in logging.level.*

Note that the Config Client does not by default poll for changes in +the Environment, and generally we would not recommend that approach +for detecting changes (although you could set it up with a +@Scheduled annotation). If you have a scaled-out client application +then it is better to broadcast the EnvironmentChangeEvent to all +the instances instead of having them polling for changes (e.g. using +the Spring Cloud +Bus).

The EnvironmentChangeEvent covers a large class of refresh use +cases, as long as you can actually make a change to the Environment +and publish the event (those APIs are public and part of core +Spring). You can verify the changes are bound to +@ConfigurationProperties beans by visiting the /configprops +endpoint (normal Spring Boot Actuator feature). For instance a +DataSource can have its maxPoolSize changed at runtime (the +default DataSource created by Spring Boot is an +@ConfigurationProperties bean) and grow capacity +dynamically. Re-binding @ConfigurationProperties does not cover +another large class of use cases, where you need more control over the +refresh, and where you need a change to be atomic over the whole +ApplicationContext. To address those concerns we have +@RefreshScope.

2.9 Refresh Scope

A Spring @Bean that is marked as @RefreshScope will get special +treatment when there is a configuration change. This addresses the +problem of stateful beans that only get their configuration injected +when they are initialized. For instance if a DataSource has open +connections when the database URL is changed via the Environment, we +probably want the holders of those connections to be able to complete +what they are doing. Then the next time someone borrows a connection +from the pool he gets one with the new URL.

Refresh scope beans are lazy proxies that initialize when they are +used (i.e. when a method is called), and the scope acts as a cache of +initialized values. To force a bean to re-initialize on the next +method call you just need to invalidate its cache entry.

The RefreshScope is a bean in the context and it has a public method +refreshAll() to refresh all beans in the scope by clearing the +target cache. There is also a refresh(String) method to refresh an +individual bean by name. This functionality is exposed in the +/refresh endpoint (over HTTP or JMX).

[Note]Note

@RefreshScope works (technically) on an @Configuration +class, but it might lead to surprising behaviour: e.g. it does not +mean that all the @Beans defined in that class are themselves +@RefreshScope. Specifically, anything that depends on those beans +cannot rely on them being updated when a refresh is initiated, unless +it is itself in @RefreshScope (in which it will be rebuilt on a +refresh and its dependencies re-injected, at which point they will be +re-initialized from the refreshed @Configuration).

2.10 Encryption and Decryption

Spring Cloud has an Environment pre-processor for decrypting +property values locally. It follows the same rules as the Config +Server, and has the same external configuration via encrypt.*. Thus +you can use encrypted values in the form {cipher}* and as long as +there is a valid key then they will be decrypted before the main +application context gets the Environment. To use the encryption +features in an application you need to include Spring Security RSA in +your classpath (Maven co-ordinates +"org.springframework.security:spring-security-rsa") and you also need +the full strength JCE extensions in your JVM.

If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:

Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).

2.11 Endpoints

For a Spring Boot Actuator application there are some additional management endpoints:

  • POST to /env to update the Environment and rebind @ConfigurationProperties and log levels
  • /refresh for re-loading the boot strap context and refreshing the @RefreshScope beans
  • /restart for closing the ApplicationContext and restarting it (disabled by default)
  • /pause and /resume for calling the Lifecycle methods (stop() and start() on the ApplicationContext)
[Note]Note

If you disable the /restart endpoint then the /pause and /resume endpoints +will also be disabled since they are just a special case of /restart.

3. Spring Cloud Commons: Common Abstractions

Patterns such as service discovery, load balancing and circuit breakers lend themselves to a common abstraction layer that can be consumed by all Spring Cloud clients, independent of the implementation (e.g. discovery via Eureka or Consul).

3.1 @EnableDiscoveryClient

Commons provides the @EnableDiscoveryClient annotation. This looks for implementations of the DiscoveryClient interface via META-INF/spring.factories. Implementations of Discovery Client will add a configuration class to spring.factories under the org.springframework.cloud.client.discovery.EnableDiscoveryClient key. Examples of DiscoveryClient implementations: are Spring Cloud Netflix Eureka, Spring Cloud Consul Discovery and Spring Cloud Zookeeper Discovery.

By default, implementations of DiscoveryClient will auto-register the local Spring Boot server with the remote discovery server. This can be disabled by setting autoRegister=false in @EnableDiscoveryClient.

[Note]Note

The use of @EnableDiscoveryClient is no longer required. It is enough to just have a DiscoveryClient implementation +on the classpath to cause the Spring Boot application to register with the service discovery server.

3.1.1 Health Indicator

Commons creates a Spring Boot HealthIndicator that DiscoveryClient implementations can participate in by implementing DiscoveryHealthIndicator. To disable the composite HealthIndicator set spring.cloud.discovery.client.composite-indicator.enabled=false. A generic HealthIndicator based on DiscoveryClient is auto-configured (DiscoveryClientHealthIndicator). To disable it, set `spring.cloud.discovery.client.health-indicator.enabled=false. To disable the description field of the DiscoveryClientHealthIndicator set spring.cloud.discovery.client.health-indicator.include-description=false, otherwise it can bubble up as the description of the rolled up HealthIndicator.

3.2 ServiceRegistry

Commons now provides a ServiceRegistry interface which provides methods like register(Registration) and deregister(Registration) which allow you to provide custom registered services. Registration is a marker interface.

@Configuration
+@EnableDiscoveryClient(autoRegister=false)
+public class MyConfiguration {
+    private ServiceRegistry registry;
+
+    public MyConfiguration(ServiceRegistry registry) {
+        this.registry = registry;
+    }
+
+    // called via some external process, such as an event or a custom actuator endpoint
+    public void register() {
+        Registration registration = constructRegistration();
+        this.registry.register(registration);
+    }
+}

Each ServiceRegistry implementation has its own Registry implementation.

  • ZookeeperRegistration used with ZookeeperServiceRegistry
  • EurekaRegistration used with EurekaServiceRegistry
  • ConsulRegistration used with ConsulServiceRegistry

If you are using the ServiceRegistry interface, you are going to need to pass the +correct Registry implementation for the ServiceRegistry implementation you +are using.

3.2.1 ServiceRegistry Auto-Registration

By default, the ServiceRegistry implementation will auto-register the running service. To disable that behavior, there are two methods. You can set @EnableDiscoveryClient(autoRegister=false) to permanently disable auto-registration. You can also set spring.cloud.service-registry.auto-registration.enabled=false to disable the behavior via configuration.

3.2.2 Service Registry Actuator Endpoint

A /service-registry actuator endpoint is provided by Commons. This endpoint relys on a Registration bean in the Spring Application Context. Calling /service-registry/instance-status via a GET will return the status of the Registration. A POST to the same endpoint with a String body will change the status of the current Registration to the new value. Please see the documentation of the ServiceRegistry implementation you are using for the allowed values for updating the status and the values retured for the status.

3.3 Spring RestTemplate as a Load Balancer Client

RestTemplate can be automatically configured to use ribbon. To create a load balanced RestTemplate create a RestTemplate @Bean and use the @LoadBalanced qualifier.

[Warning]Warning

A RestTemplate bean is no longer created via auto configuration. It must be created by individual applications.

@Configuration
+public class MyConfiguration {
+
+    @LoadBalanced
+    @Bean
+    RestTemplate restTemplate() {
+        return new RestTemplate();
+    }
+}
+
+public class MyClass {
+    @Autowired
+    private RestTemplate restTemplate;
+
+    public String doOtherStuff() {
+        String results = restTemplate.getForObject("http://stores/stores", String.class);
+        return results;
+    }
+}

The URI needs to use a virtual host name (ie. service name, not a host name). +The Ribbon client is used to create a full physical address. See +RibbonAutoConfiguration +for details of how the RestTemplate is set up.

3.3.1 Retrying Failed Requests

A load balanced RestTemplate can be configured to retry failed requests. +By default this logic is disabled, you can enable it by adding Spring Retry to your application’s classpath. The load balanced RestTemplate will +honor some of the Ribbon configuration values related to retrying failed requests. If +you would like to disable the retry logic with Spring Retry on the classpath +you can set spring.cloud.loadbalancer.retry.enabled=false. +The properties you can use are client.ribbon.MaxAutoRetries, +client.ribbon.MaxAutoRetriesNextServer, and client.ribbon.OkToRetryOnAllOperations. +See the Ribbon documentation +for a description of what there properties do.

If you would like to implement a BackOffPolicy in your retries you will need to +create a bean of type LoadBalancedBackOffPolicyFactory, and return the BackOffPolicy +you would like to use for a given service.

@Configuration
+public class MyConfiguration {
+    @Bean
+    LoadBalancedBackOffPolicyFactory backOffPolciyFactory() {
+        return new LoadBalancedBackOffPolicyFactory() {
+            @Override
+            public BackOffPolicy createBackOffPolicy(String service) {
+        		return new ExponentialBackOffPolicy();
+        	}
+        };
+    }
+}
[Note]Note

client in the above examples should be replaced with your Ribbon client’s +name.

If you want to add one or more RetryListener to your retry you will need to +create a bean of type LoadBalancedRetryListenerFactory and return the RetryListener array +you would like to use for a given service.

@Configuration
+public class MyConfiguration {
+    @Bean
+    LoadBalancedRetryListenerFactory retryListenerFactory() {
+        return new LoadBalancedRetryListenerFactory() {
+            @Override
+            public RetryListener[] createRetryListeners(String service) {
+                return new RetryListener[]{new RetryListener() {
+                    @Override
+                    public <T, E extends Throwable> boolean open(RetryContext context, RetryCallback<T, E> callback) {
+                        //TODO Do you business...
+                        return true;
+                    }
+
+                    @Override
+                     public <T, E extends Throwable> void close(RetryContext context, RetryCallback<T, E> callback, Throwable throwable) {
+                        //TODO Do you business...
+                    }
+
+                    @Override
+                    public <T, E extends Throwable> void onError(RetryContext context, RetryCallback<T, E> callback, Throwable throwable) {
+                        //TODO Do you business...
+                    }
+                }};
+            }
+        };
+    }
+}

3.4 Multiple RestTemplate objects

If you want a RestTemplate that is not load balanced, create a RestTemplate +bean and inject it as normal. To access the load balanced RestTemplate use +the @LoadBalanced qualifier when you create your @Bean.

[Important]Important

Notice the @Primary annotation on the plain RestTemplate declaration in the example below, to disambiguate the unqualified @Autowired injection.

@Configuration
+public class MyConfiguration {
+
+    @LoadBalanced
+    @Bean
+    RestTemplate loadBalanced() {
+        return new RestTemplate();
+    }
+
+    @Primary
+    @Bean
+    RestTemplate restTemplate() {
+        return new RestTemplate();
+    }
+}
+
+public class MyClass {
+    @Autowired
+    private RestTemplate restTemplate;
+
+    @Autowired
+    @LoadBalanced
+    private RestTemplate loadBalanced;
+
+    public String doOtherStuff() {
+        return loadBalanced.getForObject("http://stores/stores", String.class);
+    }
+
+    public String doStuff() {
+        return restTemplate.getForObject("https://example.com", String.class);
+    }
+}
[Tip]Tip

If you see errors like java.lang.IllegalArgumentException: Can not set org.springframework.web.client.RestTemplate field com.my.app.Foo.restTemplate to com.sun.proxy.$Proxy89 try injecting RestOperations instead or setting spring.aop.proxyTargetClass=true.

3.5 Ignore Network Interfaces

Sometimes it is useful to ignore certain named network interfaces so they can be excluded from Service Discovery registration (eg. running in a Docker container). A list of regular expressions can be set that will cause the desired network interfaces to be ignored. The following configuration will ignore the "docker0" interface and all interfaces that start with "veth".

application.yml.  +

spring:
+  cloud:
+    inetutils:
+      ignoredInterfaces:
+        - docker0
+        - veth.*

+

You can also force to use only specified network addresses using list of regular expressions:

bootstrap.yml.  +

spring:
+  cloud:
+    inetutils:
+      preferredNetworks:
+        - 192.168
+        - 10.0

+

You can also force to use only site local addresses. See Inet4Address.html.isSiteLocalAddress() for more details what is site local address.

application.yml.  +

spring:
+  cloud:
+    inetutils:
+      useOnlySiteLocalInterfaces: true

+

3.6 HTTP Client Factories

Spring Cloud Commons provides beans for creating both Apache HTTP clients (ApacheHttpClientFactory) +as well as OK HTTP clients (OkHttpClientFactory). The OkHttpClientFactory bean will only be created +if the OK HTTP jar is on the classpath. In addition, Spring Cloud Commons provides beans for creating +the connection managers used by both clients, ApacheHttpClientConnectionManagerFactory for the Apache +HTTP client and OkHttpClientConnectionPoolFactory for the OK HTTP client. You can provide +your own implementation of these beans if you would like to customize how the HTTP clients are created +in downstream projects. You can also disable the creation of these beans by setting +spring.cloud.httpclientfactories.apache.enabled or spring.cloud.httpclientfactories.ok.enabled to +false.

3.7 Spring Cloud Compatibility Verification

Due to the fact that some users have problem with setting up Spring Cloud application, we’ve decided +to add a compatibility verification mechanism. It will break if your current setup is not compatible +with Spring Cloud requirements, together with a report, showing what exactly went wrong.

At the moment we verify which version of Spring Boot is added to your classpath.

Example of a report

***************************
+APPLICATION FAILED TO START
+***************************
+
+Description:
+
+Your project setup is incompatible with our requirements due to following reasons:
+
+- Spring Boot [1.5.16.RELEASE] is not compatible with this Spring Cloud release train
+
+
+Action:
+
+Consider applying the following actions:
+
+- Change Spring Boot version to one of the following versions [1.2.x, 1.3.x] .
+You can find the latest Spring Boot versions here [https://spring.io/projects/spring-boot#learn].
+If you want to learn more about the Spring Cloud Release train compatibility, you can visit this page [https://spring.io/projects/spring-cloud#overview] and check the [Release Trains] section.

In order to disable this feature, set spring.cloud.compatibility-verifier.enabled to false. +If you want to override the compatible Spring Boot versions, just set the +spring.cloud.compatibility-verifier.compatible-boot-versions property with a comma separated list +of compatible Spring Boot versions.

Part II. Spring Cloud Config

1.3.8.RELEASE

Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With the Config Server you have a central place to manage external properties for applications across all environments. The concepts on both client and server map identically to the Spring Environment and PropertySource abstractions, so they fit very well with Spring applications, but can be used with any application running in any language. As an application moves through the deployment pipeline from dev to test and into production you can manage the configuration between those environments and be certain that applications have everything they need to run when they migrate. The default implementation of the server storage backend uses git so it easily supports labelled versions of configuration environments, as well as being accessible to a wide range of tooling for managing the content. It is easy to add alternative implementations and plug them in with Spring configuration.

4. Quick Start

Start the server:

$ cd spring-cloud-config-server
+$ ../mvnw spring-boot:run

The server is a Spring Boot application so you can run it from your +IDE instead if you prefer (the main class is +ConfigServerApplication). Then try out a client:

$ curl localhost:8888/foo/development
+{"name":"foo","label":"master","propertySources":[
+  {"name":"https://github.com/scratches/config-repo/foo-development.properties","source":{"bar":"spam"}},
+  {"name":"https://github.com/scratches/config-repo/foo.properties","source":{"foo":"bar"}}
+]}

The default strategy for locating property sources is to clone a git +repository (at spring.cloud.config.server.git.uri) and use it to +initialize a mini SpringApplication. The mini-application’s +Environment is used to enumerate property sources and publish them +via a JSON endpoint.

The HTTP service has resources in the form:

/{application}/{profile}[/{label}]
+/{application}-{profile}.yml
+/{label}/{application}-{profile}.yml
+/{application}-{profile}.properties
+/{label}/{application}-{profile}.properties

where the "application" is injected as the spring.config.name in the +SpringApplication (i.e. what is normally "application" in a regular +Spring Boot app), "profile" is an active profile (or comma-separated +list of properties), and "label" is an optional git label (defaults to +"master".)

Spring Cloud Config Server pulls configuration for remote clients +from a git repository (which must be provided):

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo

4.1 Client Side Usage

To use these features in an application, just build it as a Spring +Boot application that depends on spring-cloud-config-client (e.g. see +the test cases for the config-client, or the sample app). The most +convenient way to add the dependency is via a Spring Boot starter +org.springframework.cloud:spring-cloud-starter-config. There is also a +parent pom and BOM (spring-cloud-starter-parent) for Maven users and a +Spring IO version management properties file for Gradle and Spring CLI +users. Example Maven configuration:

pom.xml.  +

   <parent>
+       <groupId>org.springframework.boot</groupId>
+       <artifactId>spring-boot-starter-parent</artifactId>
+       <version>1.5.10.RELEASE</version>
+       <relativePath /> <!-- lookup parent from repository -->
+   </parent>
+
+<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>Edgware.SR2</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>
+
+<dependencies>
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-starter-config</artifactId>
+	</dependency>
+	<dependency>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-test</artifactId>
+		<scope>test</scope>
+	</dependency>
+</dependencies>
+
+<build>
+	<plugins>
+           <plugin>
+               <groupId>org.springframework.boot</groupId>
+               <artifactId>spring-boot-maven-plugin</artifactId>
+           </plugin>
+	</plugins>
+</build>
+
+   <!-- repositories also needed for snapshots and milestones -->

+

Then you can create a standard Spring Boot application, like this simple HTTP server:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello World!";
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}

When it runs it will pick up the external configuration from the +default local config server on port 8888 if it is running. To modify +the startup behaviour you can change the location of the config server +using bootstrap.properties (like application.properties but for +the bootstrap phase of an application context), e.g.

spring.cloud.config.uri: http://myconfigserver.com

The bootstrap properties will show up in the /env endpoint as a +high-priority property source, e.g.

$ curl localhost:8080/env
+{
+  "profiles":[],
+  "configService:https://github.com/spring-cloud-samples/config-repo/bar.properties":{"foo":"bar"},
+  "servletContextInitParams":{},
+  "systemProperties":{...},
+  ...
+}

(a property source called "configService:<URL of remote +repository>/<file name>" contains the property "foo" with value +"bar" and is highest priority).

[Note]Note

the URL in the property source name is the git repository not +the config server URL.

5. Spring Cloud Config Server

The Server provides an HTTP, resource-based API for external +configuration (name-value pairs, or equivalent YAML content). The +server is easily embeddable in a Spring Boot application using the +@EnableConfigServer annotation. So this app is a config server:

ConfigServer.java.  +

@SpringBootApplication
+@EnableConfigServer
+public class ConfigServer {
+  public static void main(String[] args) {
+    SpringApplication.run(ConfigServer.class, args);
+  }
+}

+

Like all Spring Boot apps it runs on port 8080 by default, but you +can switch it to the conventional port 8888 in various ways. The +easiest, which also sets a default configuration repository, +is by launching it with spring.config.name=configserver (there +is a configserver.yml in the Config Server jar). Another is +to use your own application.properties, e.g.

application.properties.  +

server.port: 8888
+spring.cloud.config.server.git.uri: file://${user.home}/config-repo

+

where ${user.home}/config-repo is a git repository containing +YAML and properties files.

[Note]Note

in Windows you need an extra "/" in the file URL if it is +absolute with a drive prefix, e.g. file:///${user.home}/config-repo.

[Tip]Tip

Here’s a recipe for creating the git repository in the example +above:

$ cd $HOME
+$ mkdir config-repo
+$ cd config-repo
+$ git init .
+$ echo info.foo: bar > application.properties
+$ git add -A .
+$ git commit -m "Add application.properties"
[Warning]Warning

using the local filesystem for your git repository is +intended for testing only. Use a server to host your +configuration repositories in production.

[Warning]Warning

the initial clone of your configuration repository will +be quick and efficient if you only keep text files in it. If you start +to store binary files, especially large ones, you may experience +delays on the first request for configuration and/or out of memory +errors in the server.

5.1 Environment Repository

Where do you want to store the configuration data for the Config +Server? The strategy that governs this behaviour is the +EnvironmentRepository, serving Environment objects. This +Environment is a shallow copy of the domain from the Spring +Environment (including propertySources as the main feature). The +Environment resources are parametrized by three variables:

  • {application} maps to "spring.application.name" on the client side;
  • {profile} maps to "spring.profiles.active" on the client (comma separated list); and
  • {label} which is a server side feature labelling a "versioned" set of config files.

Repository implementations generally behave just like a Spring Boot +application loading configuration files from a "spring.config.name" +equal to the {application} parameter, and "spring.profiles.active" +equal to the {profiles} parameter. Precedence rules for profiles are +also the same as in a regular Boot application: active profiles take +precedence over defaults, and if there are multiple profiles the last +one wins (like adding entries to a Map).

Example: a client application has this bootstrap configuration:

bootstrap.yml.  +

spring:
+  application:
+    name: foo
+  profiles:
+    active: dev,mysql

+

(as usual with a Spring Boot application, these properties could also +be set as environment variables or command line arguments).

If the repository is file-based, the server will create an +Environment from application.yml (shared between all clients), and +foo.yml (with foo.yml taking precedence). If the YAML files have +documents inside them that point to Spring profiles, those are applied +with higher precedence (in order of the profiles listed), and if +there are profile-specific YAML (or properties) files these are also +applied with higher precedence than the defaults. Higher precedence +translates to a PropertySource listed earlier in the +Environment. (These are the same rules as apply in a standalone +Spring Boot application.)

5.1.1 Git Backend

The default implementation of EnvironmentRepository uses a Git +backend, which is very convenient for managing upgrades and physical +environments, and also for auditing changes. To change the location of +the repository you can set the "spring.cloud.config.server.git.uri" +configuration property in the Config Server (e.g. in +application.yml). If you set it with a file: prefix it should work +from a local repository so you can get started quickly and easily +without a server, but in that case the server operates directly on the +local repository without cloning it (it doesn’t matter if it’s not +bare because the Config Server never makes changes to the "remote" +repository). To scale the Config Server up and make it highly +available, you would need to have all instances of the server pointing +to the same repository, so only a shared file system would work. Even +in that case it is better to use the ssh: protocol for a shared +filesystem repository, so that the server can clone it and use a local +working copy as a cache.

This repository implementation maps the {label} parameter of the +HTTP resource to a git label (commit id, branch name or tag). If the +git branch or tag name contains a slash ("/") then the label in the +HTTP URL should be specified with the special string "(_)" instead (to +avoid ambiguity with other URL paths). For example, if the label is +foo/bar, replacing the slash would result in a label that looks like +foo(_)bar. The inclusion of the special string "(_)" can also be +applied to the {application} parameter. Be careful with the brackets +in the URL if you are using a command line client like curl (e.g. +escape them from the shell with quotes '').

Placeholders in Git URI

Spring Cloud Config Server supports a git repository URL with +placeholders for the {application} and {profile} (and {label} if +you need it, but remember that the label is applied as a git label +anyway). So you can easily support a "one repo per application" policy +using (for example):

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/myorg/{application}

or a "one repo per profile" policy using a similar pattern but with +{profile}.

Additionally, using the special string "(_)" within your +{application} parameters can enable support for multiple +organizations (for example):

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/{application}

where {application} is provided at request time in the format +"organization(_)application".

Pattern Matching and Multiple Repositories

There is also support for more complex requirements with pattern +matching on the application and profile name. The pattern format is a +comma-separated list of {application}/{profile} names with wildcards +(where a pattern beginning with a wildcard may need to be +quoted). Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          repos:
+            simple: https://github.com/simple/config-repo
+            special:
+              pattern: special*/dev*,*special*/dev*
+              uri: https://github.com/special/config-repo
+            local:
+              pattern: local*
+              uri: file:/home/configsvc/config-repo

If {application}/{profile} does not match any of the patterns, it +will use the default uri defined under +"spring.cloud.config.server.git.uri". In the above example, for the +"simple" repository, the pattern is simple/* (i.e. it only matches +one application named "simple" in all profiles). The "local" +repository matches all application names beginning with "local" in all +profiles (the /* suffix is added automatically to any pattern that +doesn’t have a profile matcher).

[Note]Note

the "one-liner" short cut used in the "simple" example above can +only be used if the only property to be set is the URI. If you need to +set anything else (credentials, pattern, etc.) you need to use the full +form.

The pattern property in the repo is actually an array, so you can +use a YAML array (or [0], [1], etc. suffixes in properties files) +to bind to multiple patterns. You may need to do this if you are going +to run apps with multiple profiles. Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          repos:
+            development:
+              pattern:
+                - '*/development'
+                - '*/staging'
+              uri: https://github.com/development/config-repo
+            staging:
+              pattern:
+                - '*/qa'
+                - '*/production'
+              uri: https://github.com/staging/config-repo
[Note]Note

Spring Cloud will guess that a pattern containing a profile that +doesn’t end in * implies that you actually want to match a list of +profiles starting with this pattern (so */staging is a shortcut for +["*/staging", "*/staging,*"]). This is common where you need to run +apps in the "development" profile locally but also the "cloud" profile +remotely, for instance.

Every repository can also optionally store config files in +sub-directories, and patterns to search for those directories can be +specified as searchPaths. For example at the top level:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          searchPaths: foo,bar*

In this example the server searches for config files in the top level +and in the "foo/" sub-directory and also any sub-directory whose name +begins with "bar".

By default the server clones remote repositories when configuration +is first requested. The server can be configured to clone the repositories +at startup. For example at the top level:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://git/common/config-repo.git
+          repos:
+            team-a:
+                pattern: team-a-*
+                cloneOnStart: true
+                uri: https://git/team-a/config-repo.git
+            team-b:
+                pattern: team-b-*
+                cloneOnStart: false
+                uri: https://git/team-b/config-repo.git
+            team-c:
+                pattern: team-c-*
+                uri: https://git/team-a/config-repo.git

In this example the server clones team-a’s config-repo on startup before it +accepts any requests. All other repositories will not be cloned until +configuration from the repository is requested.

[Note]Note

Setting a repository to be cloned when the Config Server starts up can +help to identify a misconfigured configuration source (e.g., an invalid +repository URI) quickly, while the Config Server is starting up. With +cloneOnStart not enabled for a configuration source, the Config Server may +start successfully with a misconfigured or invalid configuration source and +not detect an error until an application requests configuration from that +configuration source.

Authentication

To use HTTP basic authentication on the remote repository add the +"username" and "password" properties separately (not in the URL), +e.g.

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          username: trolley
+          password: strongpassword

If you don’t use HTTPS and user credentials, SSH should also work out +of the box when you store keys in the default directories (~/.ssh) +and the uri points to an SSH location, +e.g. "git@github.com:configuration/cloud-configuration". It is important that an entry for the Git server be present in the ~/.ssh/known_hosts file and that it is in ssh-rsa format. Other formats (like ecdsa-sha2-nistp256) are not supported. To avoid surprises, you should ensure that only one entry is present in the known_hosts file for the Git server and that it is matching with the URL you provided to the config server. If you used a hostname in the URL, you want to have exactly that in the known_hosts file, not the IP. +The repository is accessed using JGit, so any documentation you find on +that should be applicable. HTTPS proxy settings can be set in +~/.git/config or in the same way as for any other JVM process via +system properties (-Dhttps.proxyHost and -Dhttps.proxyPort).

[Tip]Tip

If you don’t know where your ~/.git directory is use git config +--global to manipulate the settings (e.g. git config --global +http.sslVerify false).

Authentication with AWS CodeCommit

AWS CodeCommit authentication can also be +done. AWS CodeCommit uses an authentication helper when using Git from the command line. This helper is not +used with the JGit library, so a JGit CredentialProvider for AWS CodeCommit will be created if the Git +URI matches the AWS CodeCommit pattern. AWS CodeCommit URIs always look like +https://git-codecommit.${AWS_REGION}.amazonaws.com/${repopath}.

If you provide a username and password with an AWS CodeCommit URI, then these must be +the AWS accessKeyId and secretAccessKey +to be used to access the repository. If you do not specify a username and password, +then the accessKeyId and secretAccessKey will be retrieved using the +AWS Default Credential Provider Chain.

If your Git URI matches the CodeCommit URI pattern (above) then you must provide +valid AWS credentials in the username and password, or in one of the locations supported +by the default credential provider chain. AWS EC2 instances may use +IAM Roles for EC2 Instances.

Note: The aws-java-sdk-core jar is an optional dependency. If the aws-java-sdk-core jar is not on your +classpath, then the AWS Code Commit credential provider will not be created regardless of the git server URI.

Git SSH configuration using properties

By default, the JGit library used by Spring Cloud Config Server uses SSH configuration files such as ~/.ssh/known_hosts and /etc/ssh/ssh_config when connecting to Git repositories using an SSH URI. +In cloud environments such as Cloud Foundry, the local filesystem may be ephemeral or not easily accessible. For cases such as these, SSH configuration can be set using +Java properties. In order to activate property based SSH configuration, the property spring.cloud.config.server.git.ignoreLocalSshSettings must be set to true. +Example:

  spring:
+    cloud:
+      config:
+        server:
+          git:
+            uri: git@gitserver.com:team/repo1.git
+            ignoreLocalSshSettings: true
+            hostKey: someHostKey
+            hostKeyAlgorithm: ssh-rsa
+            privateKey: |
+                         -----BEGIN RSA PRIVATE KEY-----
+                         MIIEpgIBAAKCAQEAx4UbaDzY5xjW6hc9jwN0mX33XpTDVW9WqHp5AKaRbtAC3DqX
+                         IXFMPgw3K45jxRb93f8tv9vL3rD9CUG1Gv4FM+o7ds7FRES5RTjv2RT/JVNJCoqF
+                         ol8+ngLqRZCyBtQN7zYByWMRirPGoDUqdPYrj2yq+ObBBNhg5N+hOwKjjpzdj2Ud
+                         1l7R+wxIqmJo1IYyy16xS8WsjyQuyC0lL456qkd5BDZ0Ag8j2X9H9D5220Ln7s9i
+                         oezTipXipS7p7Jekf3Ywx6abJwOmB0rX79dV4qiNcGgzATnG1PkXxqt76VhcGa0W
+                         DDVHEEYGbSQ6hIGSh0I7BQun0aLRZojfE3gqHQIDAQABAoIBAQCZmGrk8BK6tXCd
+                         fY6yTiKxFzwb38IQP0ojIUWNrq0+9Xt+NsypviLHkXfXXCKKU4zUHeIGVRq5MN9b
+                         BO56/RrcQHHOoJdUWuOV2qMqJvPUtC0CpGkD+valhfD75MxoXU7s3FK7yjxy3rsG
+                         EmfA6tHV8/4a5umo5TqSd2YTm5B19AhRqiuUVI1wTB41DjULUGiMYrnYrhzQlVvj
+                         5MjnKTlYu3V8PoYDfv1GmxPPh6vlpafXEeEYN8VB97e5x3DGHjZ5UrurAmTLTdO8
+                         +AahyoKsIY612TkkQthJlt7FJAwnCGMgY6podzzvzICLFmmTXYiZ/28I4BX/mOSe
+                         pZVnfRixAoGBAO6Uiwt40/PKs53mCEWngslSCsh9oGAaLTf/XdvMns5VmuyyAyKG
+                         ti8Ol5wqBMi4GIUzjbgUvSUt+IowIrG3f5tN85wpjQ1UGVcpTnl5Qo9xaS1PFScQ
+                         xrtWZ9eNj2TsIAMp/svJsyGG3OibxfnuAIpSXNQiJPwRlW3irzpGgVx/AoGBANYW
+                         dnhshUcEHMJi3aXwR12OTDnaLoanVGLwLnkqLSYUZA7ZegpKq90UAuBdcEfgdpyi
+                         PhKpeaeIiAaNnFo8m9aoTKr+7I6/uMTlwrVnfrsVTZv3orxjwQV20YIBCVRKD1uX
+                         VhE0ozPZxwwKSPAFocpyWpGHGreGF1AIYBE9UBtjAoGBAI8bfPgJpyFyMiGBjO6z
+                         FwlJc/xlFqDusrcHL7abW5qq0L4v3R+FrJw3ZYufzLTVcKfdj6GelwJJO+8wBm+R
+                         gTKYJItEhT48duLIfTDyIpHGVm9+I1MGhh5zKuCqIhxIYr9jHloBB7kRm0rPvYY4
+                         VAykcNgyDvtAVODP+4m6JvhjAoGBALbtTqErKN47V0+JJpapLnF0KxGrqeGIjIRV
+                         cYA6V4WYGr7NeIfesecfOC356PyhgPfpcVyEztwlvwTKb3RzIT1TZN8fH4YBr6Ee
+                         KTbTjefRFhVUjQqnucAvfGi29f+9oE3Ei9f7wA+H35ocF6JvTYUsHNMIO/3gZ38N
+                         CPjyCMa9AoGBAMhsITNe3QcbsXAbdUR00dDsIFVROzyFJ2m40i4KCRM35bC/BIBs
+                         q0TY3we+ERB40U8Z2BvU61QuwaunJ2+uGadHo58VSVdggqAo0BSkH58innKKt96J
+                         69pcVH/4rmLbXdcmNYGm6iu+MlPQk4BUZknHSmVHIFdJ0EPupVaQ8RHT
+                         -----END RSA PRIVATE KEY-----

Table 5.1. SSH Configuration properties

Property NameRemarks

ignoreLocalSshSettings

If true, use property based SSH config instead of file based. Must be set at as spring.cloud.config.server.git.ignoreLocalSshSettings, not inside a repository definition.

privateKey

Valid SSH private key. Must be set if ignoreLocalSshSettings is true and Git URI is SSH format

hostKey

Valid SSH host key. Must be set if hostKeyAlgorithm is also set

hostKeyAlgorithm

One of ssh-dss, ssh-rsa, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384 ,ecdsa-sha2-nistp521. Must be set if hostKey is also set

proxyHost

Hostname for the ssh proxy connection. Is optional and used only when ignoreLocalSshSettings is true

proxyPort

Port for the ssh proxy connection. Must be set if proxyHost is also set

strictHostKeyChecking

true or false. If false, ignore errors with host key

knownHostsFile

Location of custom .known_hosts file

preferredAuthentications

Override server authentication method order. This should allow evade login prompts if server has keyboard-interactive authentication before publickey method.


Placeholders in Git Search Paths

Spring Cloud Config Server also supports a search path with +placeholders for the {application} and {profile} (and {label} if +you need it). Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          searchPaths: '{application}'

searches the repository for files in the same name as the directory +(as well as the top level). Wildcards are also valid in a search +path with placeholders (any matching directory is included in the +search).

Force pull in Git Repositories

As mentioned before Spring Cloud Config Server makes a clone of the +remote git repository and if somehow the local copy gets dirty (e.g. +folder content changes by OS process) so Spring Cloud Config Server +cannot update the local copy from remote repository.

To solve this there is a force-pull property that will make Spring Cloud +Config Server force pull from remote repository if the local copy is dirty. +Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          force-pull: true

If you have a multiple repositories configuration you can configure the +force-pull property per repository. Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://git/common/config-repo.git
+          force-pull: true
+          repos:
+            team-a:
+                pattern: team-a-*
+                uri: https://git/team-a/config-repo.git
+                force-pull: true
+            team-b:
+                pattern: team-b-*
+                uri: https://git/team-b/config-repo.git
+                force-pull: true
+            team-c:
+                pattern: team-c-*
+                uri: https://git/team-a/config-repo.git
[Note]Note

The default value for force-pull property is false.

Deleting untracked branches in Git Repositories

As Spring Cloud Config Server has a clone of the remote git repository +after check-outing branch to local repo (e.g fetching properties by label) it will keep this branch +forever or till the next server restart (which creates new local repo). +So there could be a case when remote branch is deleted but local copy of it is still available for fetching. +And if Spring Cloud Config Server client service starts with --spring.cloud.config.label=deletedRemoteBranch,master +it will fetch properties from deletedRemoteBranch local branch, but not from master.

In order to keep local repository branches clean and up to remote - deleteUntrackedBranches property could be set. +It will make Spring Cloud Config Server force delete untracked branches from local repository. +Example:

spring:
+  cloud:
+    config:
+      server:
+        git:
+          uri: https://github.com/spring-cloud-samples/config-repo
+          deleteUntrackedBranches: true
[Note]Note

The default value for deleteUntrackedBranches property is false.

5.1.2 Version Control Backend Filesystem Use

[Warning]Warning

With VCS based backends (git, svn) files are checked out or cloned to the local filesystem. By default they are put in the system temporary directory with a prefix of config-repo-. On linux, for example it could be /tmp/config-repo-<randomid>. Some operating systems routinely clean out temporary directories. This can lead to unexpected behaviour such as missing properties. To avoid this problem, change the directory Config Server uses, by setting spring.cloud.config.server.git.basedir or spring.cloud.config.server.svn.basedir to a directory that does not reside in the system temp structure.

5.1.3 File System Backend

There is also a "native" profile in the Config Server that doesn’t use +Git, but just loads the config files from the local classpath or file +system (any static URL you want to point to with +"spring.cloud.config.server.native.searchLocations"). To use the +native profile just launch the Config Server with +"spring.profiles.active=native".

[Note]Note

Remember to use the file: prefix for file resources (the +default without a prefix is usually the classpath). Just as with any +Spring Boot configuration you can embed ${}-style environment +placeholders, but remember that absolute paths in Windows require an +extra "/", e.g. file:///${user.home}/config-repo

[Warning]Warning

The default value of the searchLocations is identical to a +local Spring Boot application (so [classpath:/, classpath:/config, +file:./, file:./config]). This does not expose the +application.properties from the server to all clients because any +property sources present in the server are removed before being sent +to the client.

[Tip]Tip

A filesystem backend is great for getting started quickly and +for testing. To use it in production you need to be sure that the +file system is reliable, and shared across all instances of the +Config Server.

The search locations can contain placeholders for {application}, +{profile} and {label}. In this way you can segregate the +directories in the path, and choose a strategy that makes sense for +you (e.g. sub-directory per application, or sub-directory per +profile).

If you don’t use placeholders in the search locations, this repository +also appends the {label} parameter of the HTTP resource to a suffix +on the search path, so properties files are loaded from each search +location and a subdirectory with the same name as the label (the +labelled properties take precedence in the Spring Environment). Thus +the default behaviour with no placeholders is the same as adding a +search location ending with /{label}/. For example file:/tmp/config +is the same as file:/tmp/config,file:/tmp/config/{label}. This behavior can be +disabled by setting spring.cloud.config.server.native.addLabelLocations=false.

5.1.4 Vault Backend

Spring Cloud Config Server also supports Vault as a backend.

Vault is a tool for securely accessing secrets. A secret is anything +that you want to tightly control access to, such as API keys, passwords, +certificates, and more. Vault provides a unified interface to any secret, +while providing tight access control and recording a detailed audit log.

For more information on Vault see the Vault quickstart guide.

To enable the config server to use a Vault backend you can run your config server +with the vault profile. For example in your config server’s application.properties +you can add spring.profiles.active=vault.

By default the config server will assume your Vault server is running at +http://127.0.0.1:8200. It also will assume that the name of backend +is secret and the key is application. All of these defaults can be +configured in your config server’s application.properties. Below is a +table of configurable Vault properties. All properties are prefixed with +spring.cloud.config.server.vault.

NameDefault Value

host

127.0.0.1

port

8200

scheme

http

backend

secret

defaultKey

application

profileSeparator

,

All configurable properties can be found in +org.springframework.cloud.config.server.environment.VaultEnvironmentRepository.

With your config server running you can make HTTP requests to the server to retrieve +values from the Vault backend. To do this you will need a token for your Vault server.

First place some data in you Vault. For example

$ vault write secret/application foo=bar baz=bam
+$ vault write secret/myapp foo=myappsbar

Now make the HTTP request to your config server to retrieve the values.

$ curl -X "GET" "http://localhost:8888/myapp/default" -H "X-Config-Token: yourtoken"

You should see a response similar to this after making the above request.

{
+   "name":"myapp",
+   "profiles":[
+      "default"
+   ],
+   "label":null,
+   "version":null,
+   "state":null,
+   "propertySources":[
+      {
+         "name":"vault:myapp",
+         "source":{
+            "foo":"myappsbar"
+         }
+      },
+      {
+         "name":"vault:application",
+         "source":{
+            "baz":"bam",
+            "foo":"bar"
+         }
+      }
+   ]
+}

Multiple Properties Sources

When using Vault you can provide your applications with multiple properties sources. +For example, assume you have written data to the following paths in Vault.

secret/myApp,dev
+secret/myApp
+secret/application,dev
+secret/application

Properties written to secret/application are available to +all applications using the Config Server. An +application with the name myApp would have any properties +written to secret/myApp and secret/application available to it. +When myApp has the dev profile enabled then properties written to +all of the above paths would be available to it, with properties in +the first path in the list taking priority over the others.

5.1.5 Sharing Configuration With All Applications

File Based Repositories

With file-based (i.e. git, svn and native) repositories, resources +with file names in application* are shared between all client +applications (so application.properties, application.yml, +application-*.properties etc.). You can use resources with these +file names to configure global defaults and have them overridden by +application-specific files as necessary.

The #_property_overrides[property overrides] feature can also be used +for setting global defaults, and with placeholders applications are +allowed to override them locally.

[Tip]Tip

With the "native" profile (local file system backend) it is +recommended that you use an explicit search location that isn’t part +of the server’s own configuration. Otherwise the application* +resources in the default search locations are removed because they are +part of the server.

Vault Server

When using Vault as a backend you can share configuration with +all applications by placing configuration in +secret/application. For example, if you run this Vault command

$ vault write secret/application foo=bar baz=bam

All applications using the config server will have the properties +foo and baz available to them.

5.1.6 JDBC Backend

Spring Cloud Config Server supports JDBC (relation database) as a +backend for configuration properties. You can enable this feature by +adding spring-jdbc to the classpath, and using the "jdbc" profile, +or by adding a bean of type JdbcEnvironmentRepository. Spring Boot +will configure a data source if you include the right dependencies on +the classpath (see the user guide for more details on that).

The database needs to have a table called "PROPERTIES" with columns +"APPLICATION", "PROFILE", "LABEL" (with the usual Environment +meaning), plus "KEY" and "VALUE" for the key and value pairs in +Properties style. All fields are of type String in Java, so you can +make them VARCHAR of whatever length you need. Property values +behave in the same way as they would if they came from Spring Boot +properties files named {application}-{profile}.properties, including +all the encryption and decryption, which will be applied as +post-processing steps (i.e. not in the repository implementation +directly).

5.1.7 Composite Environment Repositories

In some scenarios you may wish to pull configuration data from multiple +environment repositories. To do this you can just enable +multiple profiles in your config server’s application properties or YAML file. +If, for example, you want to pull configuration data from a Git repository +as well as a SVN repository you would set the following properties for your +configuration server.

spring:
+  profiles:
+    active: git, svn
+  cloud:
+    config:
+      server:
+        svn:
+          uri: file:///path/to/svn/repo
+          order: 2
+        git:
+          uri: file:///path/to/git/repo
+          order: 1

In addition to each repo specifying a URI, you can also specify an order property. +The order property allows you to specify the priority order for all your repositories. +The lower the numerical value of the order property the higher priority it will have. +The priority order of a repository will help resolve any potential conflicts between +repositories that contain values for the same properties.

[Note]Note

Any type of failure when retrieving values from an environment repositoy +will result in a failure for the entire composite environment.

[Note]Note

When using a composite environment it is important that all repos contain +the same label(s). If you have an environment similar to the one above and you request +configuration data with the label master but the SVN +repo does not contain a branch called master the entire request will fail.

Custom Composite Environment Repositories

It is also possible to provide your own EnvironmentRepository bean +to be included as part of a composite environment in addition to +using one of the environment repositories from Spring Cloud. To do this your bean +must implement the EnvironmentRepository interface. If you would like to control +the priority of you custom EnvironmentRepository within the composite +environment you should also implement the Ordered interface and override the +getOrdered method. If you do not implement the Ordered interface then your +EnvironmentRepository will be given the lowest priority.

5.1.8 Property Overrides

The Config Server has an "overrides" feature that allows the operator +to provide configuration properties to all applications that cannot be +accidentally changed by the application using the normal Spring Boot +hooks. To declare overrides just add a map of name-value pairs to +spring.cloud.config.server.overrides. For example

spring:
+  cloud:
+    config:
+      server:
+        overrides:
+          foo: bar

will cause all applications that are config clients to read foo=bar +independent of their own configuration. (Of course an application can +use the data in the Config Server in any way it likes, so overrides +are not enforceable, but they do provide useful default behaviour if +they are Spring Cloud Config clients.)

[Tip]Tip

Normal, Spring environment placeholders with "${}" can be escaped +(and resolved on the client) by using backslash ("\") to escape the +"$" or the "{", e.g. \${app.foo:bar} resolves to "bar" unless the +app provides its own "app.foo". Note that in YAML you don’t need to +escape the backslash itself, but in properties files you do, when you +configure the overrides on the server.

You can change the priority of all overrides in the client to be more +like default values, allowing applications to supply their own values +in environment variables or System properties, by setting the flag +spring.cloud.config.overrideNone=true (default is false) in the +remote repository.

5.2 Health Indicator

Config Server comes with a Health Indicator that checks if the configured +EnvironmentRepository is working. By default it asks the EnvironmentRepository +for an application named app, the default profile and the default +label provided by the EnvironmentRepository implementation.

You can configure the Health Indicator to check more applications +along with custom profiles and custom labels, e.g.

spring:
+  cloud:
+    config:
+      server:
+        health:
+          repositories:
+            myservice:
+              label: mylabel
+            myservice-dev:
+              name: myservice
+              profiles: development

You can disable the Health Indicator by setting spring.cloud.config.server.health.enabled=false.

5.3 Security

You are free to secure your Config Server in any way that makes sense +to you (from physical network security to OAuth2 bearer +tokens), and Spring Security and Spring Boot make it easy to do pretty +much anything.

To use the default Spring Boot configured HTTP Basic security, just +include Spring Security on the classpath (e.g. through +spring-boot-starter-security). The default is a username of "user" +and a randomly generated password, which isn’t going to be very useful +in practice, so we recommend you configure the password (via +security.user.password) and encrypt it (see below for instructions +on how to do that).

5.4 Encryption and Decryption

[Important]Important

Prerequisites: to use the encryption and decryption features +you need the full-strength JCE installed in your JVM (it’s not there by default). +You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" +from Oracle, and follow instructions for installation (essentially replace the 2 policy files +in the JRE lib/security directory with the ones that you downloaded).

If the remote property sources contain encrypted content (values +starting with {cipher}) they will be decrypted before sending to +clients over HTTP. The main advantage of this set up is that the +property values don’t have to be in plain text when they are "at rest" +(e.g. in a git repository). If a value cannot be decrypted it is +removed from the property source and an additional property is added +with the same key, but prefixed with "invalid." and a value that means +"not applicable" (usually "<n/a>"). This is largely to prevent cipher +text being used as a password and accidentally leaking.

If you are setting up a remote config repository for config client +applications it might contain an application.yml like this, for +instance:

application.yml.  +

spring:
+  datasource:
+    username: dbuser
+    password: '{cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ'

+

Encrypted values in a .properties file must not be wrapped in quotes, otherwise the value will not be decrypted:

application.properties.  +

spring.datasource.username: dbuser
+spring.datasource.password: {cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ

+

You can safely push this plain text to a shared git repository and the +secret password is protected.

The server also exposes /encrypt and /decrypt endpoints (on the +assumption that these will be secured and only accessed by authorized +agents). If you are editing a remote config file you can use the Config Server +to encrypt values by POSTing to the /encrypt endpoint, e.g.

$ curl localhost:8888/encrypt -d mysecret
+682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
[Note]Note

If the value you are encrypting has characters in it that need to be URL encoded you should use +the --data-urlencode option to curl to make sure they are encoded properly.

[Tip]Tip

Be sure not to include any of the curl command statistics in the encrypted value. +Outputting the value to a file can help avoid this problem.

The inverse operation is also available via /decrypt (provided the server is +configured with a symmetric key or a full key pair):

$ curl localhost:8888/decrypt -d 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+mysecret
[Tip]Tip

If you are testing like this with curl, then use +--data-urlencode (instead of -d) or set an explicit Content-Type: +text/plain to make sure curl encodes the data correctly when there +are special characters ('+' is particularly tricky).

Take the encrypted value and add the {cipher} prefix before you put +it in the YAML or properties file, and before you commit and push it +to a remote, potentially insecure store.

The /encrypt and /decrypt endpoints also both accept paths of the +form /*/{name}/{profiles} which can be used to control cryptography +per application (name) and profile when clients call into the main +Environment resource.

[Note]Note

to control the cryptography in this granular way you must also +provide a @Bean of type TextEncryptorLocator that creates a +different encryptor per name and profiles. The one that is provided +by default does not do this (so all encryptions use the same key).

The spring command line client (with Spring Cloud CLI extensions +installed) can also be used to encrypt and decrypt, e.g.

$ spring encrypt mysecret --key foo
+682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+$ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+mysecret

To use a key in a file (e.g. an RSA public key for encryption) prepend +the key value with "@" and provide the file path, e.g.

$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub
+AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+...

The key argument is mandatory (despite having a -- prefix).

5.5 Key Management

The Config Server can use a symmetric (shared) key or an asymmetric +one (RSA key pair). The asymmetric choice is superior in terms of +security, but it is often more convenient to use a symmetric key since +it is just a single property value to configure in the bootstrap.properties.

To configure a symmetric key you just need to set encrypt.key to a +secret String (or use an enviroment variable ENCRYPT_KEY to keep it +out of plain text configuration files).

[Note]Note

You cannot configure an asymmetric key using encrypt.key.

To configure an asymmetric key use a keystore (e.g. as +created by the keytool utility that comes with the JDK). The +keystore properties are encrypt.keyStore.* with * equal to

  • location (a Resource location),
  • password (to unlock the keystore) and
  • alias (to identify which key in the store is to be +used).

The encryption is done with the public key, and a private key is +needed for decryption. Thus in principle you can configure only the +public key in the server if you only want to do encryption (and are +prepared to decrypt the values yourself locally with the private +key). In practice you might not want to do that because it spreads the +key management process around all the clients, instead of +concentrating it in the server. On the other hand it’s a useful option +if your config server really is relatively insecure and only a +handful of clients need the encrypted properties.

5.6 Creating a Key Store for Testing

To create a keystore for testing you can do something like this:

$ keytool -genkeypair -alias mytestkey -keyalg RSA \
+  -dname "CN=Web Server,OU=Unit,O=Organization,L=City,S=State,C=US" \
+  -keypass changeme -keystore server.jks -storepass letmein

Put the server.jks file in the classpath (for instance) and then in +your bootstrap.yml for the Config Server:

encrypt:
+  keyStore:
+    location: classpath:/server.jks
+    password: letmein
+    alias: mytestkey
+    secret: changeme

5.7 Using Multiple Keys and Key Rotation

In addition to the {cipher} prefix in encrypted property values, the +Config Server looks for {name:value} prefixes (zero or many) before +the start of the (Base64 encoded) cipher text. The keys are passed to +a TextEncryptorLocator which can do whatever logic it needs to +locate a TextEncryptor for the cipher. If you have configured a +keystore (encrypt.keystore.location) the default locator will look +for keys in the store with aliases as supplied by the "key" prefix, +i.e. with a cipher text like this:

foo:
+  bar: `{cipher}{key:testkey}...`

the locator will look for a key named "testkey". A secret can also be +supplied via a {secret:…​} value in the prefix, but if it is not +the default is to use the keystore password (which is what you get +when you build a keytore and don’t specify a secret). If you do +supply a secret it is recommended that you also encrypt the secrets +using a custom SecretLocator.

Key rotation is hardly ever necessary on cryptographic grounds if the +keys are only being used to encrypt a few bytes of configuration data +(i.e. they are not being used elsewhere), but occasionally you might +need to change the keys if there is a security breach for instance. In +that case all the clients would need to change their source config +files (e.g. in git) and use a new {key:…​} prefix in all the +ciphers, checking beforehand of course that the key alias is available +in the Config Server keystore.

[Tip]Tip

the {name:value} prefixes can also be added to plaintext posted +to the /encrypt endpoint, if you want to let the Config Server +handle all encryption as well as decryption.

5.8 Serving Encrypted Properties

Sometimes you want the clients to decrypt the configuration locally, +instead of doing it in the server. In that case you can still have +/encrypt and /decrypt endpoints (if you provide the encrypt.* +configuration to locate a key), but you need to explicitly switch off +the decryption of outgoing properties by placing +spring.cloud.config.server.encrypt.enabled=false in bootstrap.[yml|properties]. +If you don’t care about the endpoints, then it should work if you configure neither the +key nor the enabled flag.

6. Serving Alternative Formats

The default JSON format from the environment endpoints is perfect for +consumption by Spring applications because it maps directly onto the +Environment abstraction. If you prefer you can consume the same data +as YAML or Java properties by adding a suffix to the resource path +(".yml", ".yaml" or ".properties"). This can be useful for consumption +by applications that do not care about the structure of the JSON +endpoints, or the extra metadata they provide, for example an +application that is not using Spring might benefit from the simplicity +of this approach.

The YAML and properties representations have an additional flag +(provided as a boolean query parameter resolvePlaceholders) to +signal that placeholders in the source documents, in the standard +Spring ${…​} form, should be resolved in the output where possible +before rendering. This is a useful feature for consumers that don’t +know about the Spring placeholder conventions.

[Note]Note

there are limitations in using the YAML or properties formats, +mainly in relation to the loss of metadata. The JSON is structured as +an ordered list of property sources, for example, with names that +correlate with the source. The YAML and properties forms are coalesced +into a single map, even if the origin of the values has multiple +sources, and the names of the original source files are lost. The YAML +representation is not necessarily a faithful representation of the +YAML source in a backing repository either: it is constructed from a +list of flat property sources, and assumptions have to be made about +the form of the keys.

7. Serving Plain Text

Instead of using the Environment abstraction (or one of the +alternative representations of it in YAML or properties format) your +applications might need generic plain text configuration files, +tailored to their environment. The Config Server provides these +through an additional endpoint at /{name}/{profile}/{label}/{path} +where "name", "profile" and "label" have the same meaning as the +regular environment endpoint, but "path" is a file name +(e.g. log.xml). The source files for this endpoint are located in +the same way as for the environment endpoints: the same search path is +used as for properties or YAML files, but instead of aggregating all +matching resources, only the first one to match is returned.

After a resource is located, placeholders in the normal format +(${…​}) are resolved using the effective Environment for the +application name, profile and label supplied. In this way the resource +endpoint is tightly integrated with the environment +endpoints. Example, if you have this layout for a GIT (or SVN) +repository:

application.yml
+nginx.conf

where nginx.conf looks like this:

server {
+    listen              80;
+    server_name         ${nginx.server.name};
+}

and application.yml like this:

nginx:
+  server:
+    name: example.com
+---
+spring:
+  profiles: development
+nginx:
+  server:
+    name: develop.com

then the /foo/default/master/nginx.conf resource looks like this:

server {
+    listen              80;
+    server_name         example.com;
+}

and /foo/development/master/nginx.conf like this:

server {
+    listen              80;
+    server_name         develop.com;
+}
[Note]Note

Just like the source files for environment configuration, the +"profile" is used to resolve the file name, so if you want a +profile-specific file then /*/development/*/logback.xml will be +resolved by a file called logback-development.xml (in preference +to logback.xml).

[Note]Note

If you do not want to supply the label and let the server use the default label, you can supply a useDefaultLabel request parameter. So, the above example for the default profile could look like /foo/default/nginx.conf?useDefaultLabel.

8. Embedding the Config Server

The Config Server runs best as a standalone application, but if you +need to you can embed it in another application. Just use the +@EnableConfigServer annotation. An optional property that can be +useful in this case is spring.cloud.config.server.bootstrap which is +a flag to indicate that the server should configure itself from its +own remote repository. The flag is off by default because it can delay +startup, but when embedded in another application it makes sense to +initialize the same way as any other application.

[Note]Note

It should be obvious, but remember that if you use the bootstrap +flag the config server will need to have its name and repository URI +configured in bootstrap.yml.

To change the location of the server endpoints you can (optionally) +set spring.cloud.config.server.prefix, e.g. "/config", to serve the +resources under a prefix. The prefix should start but not end with a +"/". It is applied to the @RequestMappings in the Config Server +(i.e. underneath the Spring Boot prefixes server.servletPath and +server.contextPath).

If you want to read the configuration for an application directly from +the backend repository (instead of from the config server) that’s +basically an embedded config server with no endpoints. You can switch +off the endpoints entirely if you don’t use the @EnableConfigServer +annotation (just set spring.cloud.config.server.bootstrap=true).

9. Push Notifications and Spring Cloud Bus

Many source code repository providers (like Github, Gitlab or Bitbucket +for instance) will notify you of changes in a repository through a +webhook. You can configure the webhook via the provider’s user +interface as a URL and a set of events in which you are +interested. For instance +Github +will POST to the webhook with a JSON body containing a list of +commits, and a header "X-Github-Event" equal to "push". If you add a +dependency on the spring-cloud-config-monitor library and activate +the Spring Cloud Bus in your Config Server, then a "/monitor" endpoint +is enabled.

When the webhook is activated the Config Server will send a +RefreshRemoteApplicationEvent targeted at the applications it thinks +might have changed. The change detection can be strategized, but by +default it just looks for changes in files that match the application +name (e.g. "foo.properties" is targeted at the "foo" application, and +"application.properties" is targeted at all applications). The strategy +if you want to override the behaviour is PropertyPathNotificationExtractor +which accepts the request headers and body as parameters and returns a list +of file paths that changed.

The default configuration works out of the box with Github, Gitlab or +Bitbucket. In addition to the JSON notifications from Github, Gitlab +or Bitbucket you can trigger a change notification by POSTing to +"/monitor" with a form-encoded body parameters path={name}. This will +broadcast to applications matching the "{name}" pattern (can contain +wildcards).

[Note]Note

the RefreshRemoteApplicationEvent will only be transmitted if +the spring-cloud-bus is activated in the Config Server and in the +client application.

[Note]Note

the default configuration also detects filesystem changes in +local git repositories (the webhook is not used in that case but as +soon as you edit a config file a refresh will be broadcast).

10. Spring Cloud Config Client

A Spring Boot application can take immediate advantage of the Spring +Config Server (or other external property sources provided by the +application developer), and it will also pick up some additional +useful features related to Environment change events.

10.1 Config First Bootstrap

This is the default behaviour for any application which has the Spring +Cloud Config Client on the classpath. When a config client starts up +it binds to the Config Server (via the bootstrap configuration +property spring.cloud.config.uri) and initializes Spring +Environment with remote property sources.

The net result of this is that all client apps that want to consume +the Config Server need a bootstrap.yml (or an environment variable) +with the server address in spring.cloud.config.uri (defaults to +"http://localhost:8888").

10.2 Discovery First Bootstrap

If you are using a `DiscoveryClient implementation, such as Spring Cloud Netflix +and Eureka Service Discovery or Spring Cloud Consul (Spring Cloud Zookeeper does +not support this yet), then you can have the Config Server register with the +Discovery Service if you want to, but in the default "Config First" mode, +clients won’t be able to take advantage of the registration.

If you prefer to use DiscoveryClient to locate the Config Server, you can do +that by setting spring.cloud.config.discovery.enabled=true (default +"false"). The net result of that is that client apps all need a +bootstrap.yml (or an environment variable) with the appropriate discovery +configuration. For example, with Spring Cloud Netflix, you need to define the +Eureka server address, e.g. in eureka.client.serviceUrl.defaultZone. The +price for using this option is an extra network round trip on start up to +locate the service registration. The benefit is that the Config Server +can change its co-ordinates, as long as the Discovery Service is a fixed point. The +default service id is "configserver" but you can change that on the +client with spring.cloud.config.discovery.serviceId (and on the server +in the usual way for a service, e.g. by setting spring.application.name).

The discovery client implementations all support some kind of metadata +map (e.g. for Eureka we have eureka.instance.metadataMap). Some +additional properties of the Config Server may need to be configured +in its service registration metadata so that clients can connect +correctly. If the Config Server is secured with HTTP Basic you can +configure the credentials as "username" and "password". And if the +Config Server has a context path you can set "configPath". Example, +for a Config Server that is a Eureka client:

bootstrap.yml.  +

eureka:
+  instance:
+    ...
+    metadataMap:
+      user: osufhalskjrtl
+      password: lviuhlszvaorhvlo5847
+      configPath: /config

+

10.3 Config Client Fail Fast

In some cases, it may be desirable to fail startup of a service if +it cannot connect to the Config Server. If this is the desired +behavior, set the bootstrap configuration property +spring.cloud.config.failFast=true and the client will halt with +an Exception.

10.4 Config Client Retry

If you expect that the config server may occasionally be unavailable when +your app starts, you can ask it to keep trying after a failure. First you need +to set spring.cloud.config.failFast=true, and then you need to add +spring-retry and spring-boot-starter-aop to your classpath. The default +behaviour is to retry 6 times with an initial backoff interval of 1000ms and an +exponential multiplier of 1.1 for subsequent backoffs. You can configure these +properties (and others) using spring.cloud.config.retry.* configuration properties.

[Tip]Tip

To take full control of the retry add a @Bean of type +RetryOperationsInterceptor with id "configServerRetryInterceptor". Spring +Retry has a RetryInterceptorBuilder that makes it easy to create one.

10.5 Locating Remote Configuration Resources

The Config Service serves property sources from /{name}/{profile}/{label}, where the default bindings in the client app are

  • "name" = ${spring.application.name}
  • "profile" = ${spring.profiles.active} (actually Environment.getActiveProfiles())
  • "label" = "master"

All of them can be overridden by setting spring.cloud.config.* +(where * is "name", "profile" or "label"). The "label" is useful for +rolling back to previous versions of configuration; with the default +Config Server implementation it can be a git label, branch name or +commit id. Label can also be provided as a comma-separated list, in +which case the items in the list are tried on-by-one until one succeeds. +This can be useful when working on a feature branch, for instance, +when you might want to align the config label with your branch, but +make it optional (e.g. spring.cloud.config.label=myfeature,develop).

10.6 Security

If you use HTTP Basic security on the server then clients just need to +know the password (and username if it isn’t the default). You can do +that via the config server URI, or via separate username and password +properties, e.g.

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+     uri: https://user:secret@myconfig.mycompany.com

+

or

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+     uri: https://myconfig.mycompany.com
+     username: user
+     password: secret

+

The spring.cloud.config.password and spring.cloud.config.username +values override anything that is provided in the URI.

If you deploy your apps on Cloud Foundry then the best way to provide +the password is through service credentials, e.g. in the URI, since +then it doesn’t even need to be in a config file. An example which +works locally and for a user-provided service on Cloud Foundry named +"configserver":

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+     uri: ${vcap.services.configserver.credentials.uri:http://user:password@localhost:8888}

+

If you use another form of security you might need to provide a +RestTemplate to the ConfigServicePropertySourceLocator (e.g. by +grabbing it in the bootstrap context and injecting one).

10.6.1 Health Indicator

The Config Client supplies a Spring Boot Health Indicator that attempts to load configuration from Config Server. The health indicator can be disabled by setting health.config.enabled=false. The response is also cached for performance reasons. The default cache time to live is 5 minutes. To change that value set the health.config.time-to-live property (in milliseconds).

10.6.2 Providing A Custom RestTemplate

In some cases you might need to customize the requests made to the config server from +the client. Typically this involves passing special Authorization headers to +authenticate requests to the server. To provide a custom RestTemplate follow the +steps below.

  1. Create a new configuration bean with an implementation of PropertySourceLocator.

CustomConfigServiceBootstrapConfiguration.java.  +

@Configuration
+public class CustomConfigServiceBootstrapConfiguration {
+    @Bean
+    public ConfigServicePropertySourceLocator configServicePropertySourceLocator() {
+        ConfigClientProperties clientProperties = configClientProperties();
+       ConfigServicePropertySourceLocator configServicePropertySourceLocator =  new ConfigServicePropertySourceLocator(clientProperties);
+        configServicePropertySourceLocator.setRestTemplate(customRestTemplate(clientProperties));
+        return configServicePropertySourceLocator;
+    }
+}

+

  1. In resources/META-INF create a file called +spring.factories and specify your custom configuration.

spring.factories.  +

org.springframework.cloud.bootstrap.BootstrapConfiguration = com.my.config.client.CustomConfigServiceBootstrapConfiguration

+

10.6.3 Vault

When using Vault as a backend to your config server the client will need to +supply a token for the server to retrieve values from Vault. This token +can be provided within the client by setting spring.cloud.config.token +in bootstrap.yml.

bootstrap.yml.  +

spring:
+  cloud:
+    config:
+      token: YourVaultToken

+

10.7 Vault

10.7.1 Nested Keys In Vault

Vault supports the ability to nest keys in a value stored in Vault. For example

echo -n '{"appA": {"secret": "appAsecret"}, "bar": "baz"}' | vault write secret/myapp -

This command will write a JSON object to your Vault. To access these values in Spring +you would use the traditional dot(.) annotation. For example

@Value("${appA.secret}")
+String name = "World";

The above code would set the name variable to appAsecret.

Part III. Spring Cloud Netflix

1.3.8.RELEASE

This project provides Netflix OSS integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with battle-tested Netflix components. The +patterns provided include Service Discovery (Eureka), Circuit Breaker (Hystrix), +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon).

11. Service Discovery: Eureka Clients

Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Eureka is the Netflix Service Discovery Server and Client. The server can be configured and deployed to be highly available, with each server replicating state about the registered services to the others.

11.1 How to Include Eureka Client

To include Eureka Client in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-eureka-client. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

11.2 Registering with Eureka

When a client registers with Eureka, it provides meta-data about itself +such as host and port, health indicator URL, home page etc. Eureka +receives heartbeat messages from each instance belonging to a service. +If the heartbeat fails over a configurable timetable, the instance is +normally removed from the registry.

Example eureka client:

@Configuration
+@ComponentScan
+@EnableAutoConfiguration
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello world";
+    }
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

(i.e. utterly normal Spring Boot app). By having spring-cloud-starter-netflix-eureka-client + on the classpath your application will automatically register with the Eureka Server. Configuration is required to +locate the Eureka server. Example:

application.yml.  +

eureka:
+  client:
+    serviceUrl:
+      defaultZone: http://localhost:8761/eureka/

+

where "defaultZone" is a magic string fallback value that provides the +service URL for any client that doesn’t express a preference +(i.e. it’s a useful default).

The default application name (service ID), virtual host and non-secure +port, taken from the Environment, are ${spring.application.name}, +${spring.application.name} and ${server.port} respectively.

Having spring-cloud-starter-netflix-eureka-client on the classpath +makes the app into both a Eureka "instance" +(i.e. it registers itself) and a "client" (i.e. it can query the +registry to locate other services). The instance behaviour is driven +by eureka.instance.* configuration keys, but the defaults will be +fine if you ensure that your application has a +spring.application.name (this is the default for the Eureka service +ID, or VIP).

See EurekaInstanceConfigBean and EurekaClientConfigBean for more details of the configurable options.

To disable the Eureka Discovery Client you can set eureka.client.enabled to false.

11.3 Authenticating with the Eureka Server

HTTP basic authentication will be automatically added to your eureka +client if one of the eureka.client.serviceUrl.defaultZone URLs has +credentials embedded in it (curl style, like +http://user:password@localhost:8761/eureka). For more complex needs +you can create a @Bean of type DiscoveryClientOptionalArgs and +inject ClientFilter instances into it, all of which will be applied +to the calls from the client to the server.

[Note]Note

Because of a limitation in Eureka it isn’t possible to support +per-server basic auth credentials, so only the first set that are +found will be used.

11.4 Status Page and Health Indicator

The status page and health indicators for a Eureka instance default to +"/info" and "/health" respectively, which are the default locations of +useful endpoints in a Spring Boot Actuator application. You need to +change these, even for an Actuator application if you use a +non-default context path or servlet path +(e.g. server.servletPath=/foo) Example:

application.yml.  +

eureka:
+  instance:
+    statusPageUrlPath: ${server.servletPath}/info
+    healthCheckUrlPath: ${server.servletPath}/health

+

These links show up in the metadata that is consumed by clients, and +used in some scenarios to decide whether to send requests to your +application, so it’s helpful if they are accurate.

[Note]Note

In Dalston it was also required to set the status and health check URLs when changing +that management context path. This requirement was removed beinging in Edgware.

11.5 Registering a Secure Application

If your app wants to be contacted over HTTPS you can set two flags in +the EurekaInstanceConfig, viz +eureka.instance.[nonSecurePortEnabled,securePortEnabled]=[false,true] +respectively. This will make Eureka publish instance information +showing an explicit preference for secure communication. The Spring +Cloud DiscoveryClient will always return a URI starting with https for a +service configured this way, and the Eureka (native) instance +information will have a secure health check URL.

Because of the way +Eureka works internally, it will still publish a non-secure URL for +status and home page unless you also override those explicitly. +You can use placeholders to configure the eureka instance urls, +e.g.

application.yml.  +

eureka:
+  instance:
+    statusPageUrl: https://${eureka.hostname}/info
+    healthCheckUrl: https://${eureka.hostname}/health
+    homePageUrl: https://${eureka.hostname}/

+

(Note that ${eureka.hostname} is a native placeholder only available +in later versions of Eureka. You could achieve the same thing with +Spring placeholders as well, e.g. using ${eureka.instance.hostName}.)

[Note]Note

If your app is running behind a proxy, and the SSL termination +is in the proxy (e.g. if you run in Cloud Foundry or other platforms +as a service) then you will need to ensure that the proxy "forwarded" +headers are intercepted and handled by the application. An embedded +Tomcat container in a Spring Boot app does this automatically if it +has explicit configuration for the 'X-Forwarded-\*` headers. A sign +that you got this wrong will be that the links rendered by your app to +itself will be wrong (the wrong host, port or protocol).

11.6 Eureka’s Health Checks

By default, Eureka uses the client heartbeat to determine if a client is up. +Unless specified otherwise the Discovery Client will not propagate the +current health check status of the application per the Spring Boot Actuator. Which means +that after successful registration Eureka will always announce that the +application is in 'UP' state. This behaviour can be altered by enabling +Eureka health checks, which results in propagating application status +to Eureka. As a consequence every other application won’t be sending +traffic to application in state other then 'UP'.

application.yml.  +

eureka:
+  client:
+    healthcheck:
+      enabled: true

+

[Warning]Warning

eureka.client.healthcheck.enabled=true should only be set in application.yml. Setting the value in bootstrap.yml will cause undesirable side effects like registering in eureka with an UNKNOWN status.

If you require more control over the health checks, you may consider +implementing your own com.netflix.appinfo.HealthCheckHandler.

11.7 Eureka Metadata for Instances and Clients

It’s worth spending a bit of time understanding how the Eureka metadata works, so you can use it in a way that makes sense in your platform. There is standard metadata for things like hostname, IP address, port numbers, status page and health check. These are published in the service registry and used by clients to contact the services in a straightforward way. Additional metadata can be added to the instance registration in the eureka.instance.metadataMap, and this will be accessible in the remote clients, but in general will not change the behaviour of the client, unless it is made aware of the meaning of the metadata. There are a couple of special cases described below where Spring Cloud already assigns meaning to the metadata map.

11.7.1 Using Eureka on Cloud Foundry

Cloud Foundry has a global router so that all instances of the same app have the same hostname (it’s the same in other PaaS solutions with a similar architecture). This isn’t necessarily a barrier to using Eureka, but if you use the router (recommended, or even mandatory depending on the way your platform was set up), you need to explicitly set the hostname and port numbers (secure or non-secure) so that they use the router. You might also want to use instance metadata so you can distinguish between the instances on the client (e.g. in a custom load balancer). By default, the eureka.instance.instanceId is vcap.application.instance_id. For example:

application.yml.  +

eureka:
+  instance:
+    hostname: ${vcap.application.uris[0]}
+    nonSecurePort: 80

+

Depending on the way the security rules are set up in your Cloud Foundry instance, you might be able to register and use the IP address of the host VM for direct service-to-service calls. This feature is not (yet) available on Pivotal Web Services (PWS).

11.7.2 Using Eureka on AWS

If the application is planned to be deployed to an AWS cloud, then the Eureka instance will have to be configured to be AWS aware and this can be done by customizing the EurekaInstanceConfigBean the following way:

@Bean
+@Profile("!default")
+public EurekaInstanceConfigBean eurekaInstanceConfig(InetUtils inetUtils) {
+  EurekaInstanceConfigBean b = new EurekaInstanceConfigBean(inetUtils);
+  AmazonInfo info = AmazonInfo.Builder.newBuilder().autoBuild("eureka");
+  b.setDataCenterInfo(info);
+  return b;
+}

11.7.3 Changing the Eureka Instance ID

A vanilla Netflix Eureka instance is registered with an ID that is equal to its host name (i.e. only one service per host). Spring Cloud Eureka provides a sensible default that looks like this: ${spring.cloud.client.hostname}:${spring.application.name}:${spring.application.instance_id:${server.port}}}. For example myhost:myappname:8080.

Using Spring Cloud you can override this by providing a unique identifier in eureka.instance.instanceId. For example:

application.yml.  +

eureka:
+  instance:
+    instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}

+

With this metadata, and multiple service instances deployed on +localhost, the random value will kick in there to make the instance +unique. In Cloud Foundry the vcap.application.instance_id will be +populated automatically in a Spring Boot application, so the +random value will not be needed.

11.8 Using the EurekaClient

Once you have an app that is a discovery client you can use it to +discover service instances from the Eureka Server. One way to do that is to use the native +com.netflix.discovery.EurekaClient (as opposed to the Spring +Cloud DiscoveryClient), e.g.

@Autowired
+private EurekaClient discoveryClient;
+
+public String serviceUrl() {
+    InstanceInfo instance = discoveryClient.getNextServerFromEureka("STORES", false);
+    return instance.getHomePageUrl();
+}
[Tip]Tip

Don’t use the EurekaClient in @PostConstruct method or in a +@Scheduled method (or anywhere where the ApplicationContext might +not be started yet). It is initialized in a SmartLifecycle (with +phase=0) so the earliest you can rely on it being available is in +another SmartLifecycle with higher phase.

11.8.1 EurekaClient without Jersey

By default, EurekaClient uses Jersey for HTTP communication. If you wish +to avoid dependencies from Jersey, you can exclude it from your dependencies. +Spring Cloud will auto configure a transport client based on Spring +RestTemplate.

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-starter-eureka</artifactId>
+    <exclusions>
+        <exclusion>
+            <groupId>com.sun.jersey</groupId>
+            <artifactId>jersey-client</artifactId>
+        </exclusion>
+        <exclusion>
+            <groupId>com.sun.jersey</groupId>
+            <artifactId>jersey-core</artifactId>
+        </exclusion>
+        <exclusion>
+            <groupId>com.sun.jersey.contribs</groupId>
+            <artifactId>jersey-apache-client4</artifactId>
+        </exclusion>
+    </exclusions>
+</dependency>

11.9 Alternatives to the native Netflix EurekaClient

You don’t have to use the raw Netflix EurekaClient and usually it +is more convenient to use it behind a wrapper of some sort. Spring +Cloud has support for Feign (a REST client +builder) and also Spring RestTemplate using +the logical Eureka service identifiers (VIPs) instead of physical +URLs. To configure Ribbon with a fixed list of physical servers you +can simply set <client>.ribbon.listOfServers to a comma-separated +list of physical addresses (or hostnames), where <client> is the ID +of the client.

You can also use the org.springframework.cloud.client.discovery.DiscoveryClient +which provides a simple API for discovery clients that is not specific +to Netflix, e.g.

@Autowired
+private DiscoveryClient discoveryClient;
+
+public String serviceUrl() {
+    List<ServiceInstance> list = discoveryClient.getInstances("STORES");
+    if (list != null && list.size() > 0 ) {
+        return list.get(0).getUri();
+    }
+    return null;
+}

11.10 Why is it so Slow to Register a Service?

Being an instance also involves a periodic heartbeat to the registry +(via the client’s serviceUrl) with default duration 30 seconds. A +service is not available for discovery by clients until the instance, +the server and the client all have the same metadata in their local +cache (so it could take 3 heartbeats). You can change the period using +eureka.instance.leaseRenewalIntervalInSeconds and this will speed up +the process of getting clients connected to other services. In +production it’s probably better to stick with the default because +there are some computations internally in the server that make +assumptions about the lease renewal period.

11.11 Zones

If you have deployed Eureka clients to multiple zones than you may prefer that +those clients leverage services within the same zone before trying services +in another zone. To do this you need to configure your Eureka clients correctly.

First, you need to make sure you have Eureka servers deployed to each zone and that +they are peers of each other. See the section on zones and regions +for more information.

Next you need to tell Eureka which zone your service is in. You can do this using +the metadataMap property. For example if service 1 is deployed to both zone 1 +and zone 2 you would need to set the following Eureka properties in service 1

Service 1 in Zone 1

eureka.instance.metadataMap.zone = zone1
+eureka.client.preferSameZoneEureka = true

Service 1 in Zone 2

eureka.instance.metadataMap.zone = zone2
+eureka.client.preferSameZoneEureka = true

12. Service Discovery: Eureka Server

12.1 How to Include Eureka Server

To include Eureka Server in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-eureka-server. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

12.2 How to Run a Eureka Server

Example eureka server;

@SpringBootApplication
+@EnableEurekaServer
+public class Application {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

The server has a home page with a UI, and HTTP API endpoints per the +normal Eureka functionality under /eureka/*.

Eureka background reading: see flux capacitor and google group discussion.

[Tip]Tip

Due to Gradle’s dependency resolution rules and the lack of a parent bom feature, simply depending on spring-cloud-starter-netflix-eureka-server can cause failures on application startup. To remedy this the Spring Boot Gradle plugin must be added and the Spring cloud starter parent bom must be imported like so:

build.gradle.  +

buildscript {
+  dependencies {
+    classpath("org.springframework.boot:spring-boot-gradle-plugin:1.5.10.RELEASE")
+  }
+}
+
+apply plugin: "spring-boot"
+
+dependencyManagement {
+  imports {
+    mavenBom "org.springframework.cloud:spring-cloud-dependencies:Edgware.SR2"
+  }
+}

+

12.3 High Availability, Zones and Regions

The Eureka server does not have a backend store, but the service +instances in the registry all have to send heartbeats to keep their +registrations up to date (so this can be done in memory). Clients also +have an in-memory cache of eureka registrations (so they don’t have to +go to the registry for every single request to a service).

By default every Eureka server is also a Eureka client and requires +(at least one) service URL to locate a peer. If you don’t provide it +the service will run and work, but it will shower your logs with a lot +of noise about not being able to register with the peer.

See also below for details of Ribbon +support on the client side for Zones and Regions.

12.4 Standalone Mode

The combination of the two caches (client and server) and the +heartbeats make a standalone Eureka server fairly resilient to +failure, as long as there is some sort of monitor or elastic runtime +keeping it alive (e.g. Cloud Foundry). In standalone mode, you might +prefer to switch off the client side behaviour, so it doesn’t keep +trying and failing to reach its peers. Example:

application.yml (Standalone Eureka Server).  +

server:
+  port: 8761
+
+eureka:
+  instance:
+    hostname: localhost
+  client:
+    registerWithEureka: false
+    fetchRegistry: false
+    serviceUrl:
+      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

+

Notice that the serviceUrl is pointing to the same host as the local +instance.

12.5 Peer Awareness

Eureka can be made even more resilient and available by running +multiple instances and asking them to register with each other. In +fact, this is the default behaviour, so all you need to do to make it +work is add a valid serviceUrl to a peer, e.g.

application.yml (Two Peer Aware Eureka Servers).  +

---
+spring:
+  profiles: peer1
+eureka:
+  instance:
+    hostname: peer1
+  client:
+    serviceUrl:
+      defaultZone: http://peer2/eureka/
+
+---
+spring:
+  profiles: peer2
+eureka:
+  instance:
+    hostname: peer2
+  client:
+    serviceUrl:
+      defaultZone: http://peer1/eureka/

+

In this example we have a YAML file that can be used to run the same +server on 2 hosts (peer1 and peer2), by running it in different +Spring profiles. You could use this configuration to test the peer +awareness on a single host (there’s not much value in doing that in +production) by manipulating /etc/hosts to resolve the host names. In +fact, the eureka.instance.hostname is not needed if you are running +on a machine that knows its own hostname (it is looked up using +java.net.InetAddress by default).

You can add multiple peers to a system, and as long as they are all +directly connected to each other, they will synchronize +the registrations amongst themselves.

application.yml (Three Peer Aware Eureka Servers).  +

eureka:
+  client:
+    serviceUrl:
+      defaultZone: http://peer1/eureka/,http://peer2/eureka/,http://peer3/eureka/
+
+---
+spring:
+  profiles: peer1
+eureka:
+  instance:
+    hostname: peer1
+
+---
+spring:
+  profiles: peer2
+eureka:
+  instance:
+    hostname: peer2
+
+---
+spring:
+  profiles: peer3
+eureka:
+  instance:
+    hostname: peer3

+

12.6 Prefer IP Address

In some cases, it is preferable for Eureka to advertise the IP Adresses +of services rather than the hostname. Set eureka.instance.preferIpAddress +to true and when the application registers with eureka, it will use its +IP Address rather than its hostname.

[Tip]Tip

If hostname can’t be determined by Java, then IP address is sent to Eureka. +Only explict way of setting hostname is by using eureka.instance.hostname. +You can set your hostname at the run time using environment variable, for +example eureka.instance.hostname=${HOST_NAME}.

13. Circuit Breaker: Hystrix Clients

Netflix has created a library called Hystrix that implements the circuit breaker pattern. In a microservice architecture it is common to have multiple layers of service calls.

Figure 13.1. Microservice Graph

Hystrix

A service failure in the lower level of services can cause cascading failure all the way up to the user. When calls to a particular service is greater than circuitBreaker.requestVolumeThreshold (default: 20 requests) and failue percentage is greater than circuitBreaker.errorThresholdPercentage (default: >50%) in a rolling window defined by metrics.rollingStats.timeInMilliseconds (default: 10 seconds), the circuit opens and the call is not made. In cases of error and an open circuit a fallback can be provided by the developer.

Figure 13.2. Hystrix fallback prevents cascading failures

HystrixFallback

Having an open circuit stops cascading failures and allows overwhelmed or failing services time to heal. The fallback can be another Hystrix protected call, static data or a sane empty value. Fallbacks may be chained so the first fallback makes some other business call which in turn falls back to static data.

13.1 How to Include Hystrix

To include Hystrix in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-hystrix. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

Example boot app:

@SpringBootApplication
+@EnableCircuitBreaker
+public class Application {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}
+
+@Component
+public class StoreIntegration {
+
+    @HystrixCommand(fallbackMethod = "defaultStores")
+    public Object getStores(Map<String, Object> parameters) {
+        //do stuff that might fail
+    }
+
+    public Object defaultStores(Map<String, Object> parameters) {
+        return /* something useful */;
+    }
+}

The @HystrixCommand is provided by a Netflix contrib library called +"javanica". +Spring Cloud automatically wraps Spring beans with that +annotation in a proxy that is connected to the Hystrix circuit +breaker. The circuit breaker calculates when to open and close the +circuit, and what to do in case of a failure.

To configure the @HystrixCommand you can use the commandProperties +attribute with a list of @HystrixProperty annotations. See +here +for more details. See the Hystrix wiki +for details on the properties available.

13.2 Propagating the Security Context or using Spring Scopes

If you want some thread local context to propagate into a @HystrixCommand the default declaration will not work because it executes the command in a thread pool (in case of timeouts). You can switch Hystrix to use the same thread as the caller using some configuration, or directly in the annotation, by asking it to use a different "Isolation Strategy". For example:

@HystrixCommand(fallbackMethod = "stubMyService",
+    commandProperties = {
+      @HystrixProperty(name="execution.isolation.strategy", value="SEMAPHORE")
+    }
+)
+...

The same thing applies if you are using @SessionScope or @RequestScope. You will know when you need to do this because of a runtime exception that says it can’t find the scoped context.

You also have the option to set the hystrix.shareSecurityContext property to true. Doing so will auto configure an Hystrix concurrency strategy plugin hook who will transfer the SecurityContext from your main thread to the one used by the Hystrix command. Hystrix does not allow multiple hystrix concurrency strategy to be registered so an extension mechanism is available by declaring your own HystrixConcurrencyStrategy as a Spring bean. Spring Cloud will lookup for your implementation within the Spring context and wrap it inside its own plugin.

13.3 Health Indicator

The state of the connected circuit breakers are also exposed in the +/health endpoint of the calling application.

{
+    "hystrix": {
+        "openCircuitBreakers": [
+            "StoreIntegration::getStoresByLocationLink"
+        ],
+        "status": "CIRCUIT_OPEN"
+    },
+    "status": "UP"
+}

13.4 Hystrix Metrics Stream

To enable the Hystrix metrics stream include a dependency on spring-boot-starter-actuator. This will expose the /hystrix.stream as a management endpoint.

    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-actuator</artifactId>
+    </dependency>

14. Circuit Breaker: Hystrix Dashboard

One of the main benefits of Hystrix is the set of metrics it gathers about each HystrixCommand. The Hystrix Dashboard displays the health of each circuit breaker in an efficient manner.

Figure 14.1. Hystrix Dashboard

Hystrix

15. Hystrix Timeouts And Ribbon Clients

When using Hystrix commands that wrap Ribbon clients you want to make sure your Hystrix timeout +is configured to be longer than the configured Ribbon timeout, including any potential +retries that might be made. For example, if your Ribbon connection timeout is one second and +the Ribbon client might retry the request three times, than your Hystrix timeout should +be slightly more than three seconds.

15.1 How to Include Hystrix Dashboard

To include the Hystrix Dashboard in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-hystrix-dashboard. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

To run the Hystrix Dashboard annotate your Spring Boot main class with @EnableHystrixDashboard. You then visit /hystrix and point the dashboard to an individual instances /hystrix.stream endpoint in a Hystrix client application.

[Note]Note

When connecting to a /hystrix.stream endpoint which uses HTTPS the certificate used by the server +must be trusted by the JVM. If the certificate is not trusted you must import the certificate into the JVM +in order for the Hystrix Dashboard to make a successful connection to the stream endpoint.

15.2 Turbine

Looking at an individual instances Hystrix data is not very useful in terms of the overall health of the system. Turbine is an application that aggregates all of the relevant /hystrix.stream endpoints into a combined /turbine.stream for use in the Hystrix Dashboard. Individual instances are located via Eureka. Running Turbine is as simple as annotating your main class with the @EnableTurbine annotation (e.g. using spring-cloud-starter-netflix-turbine to set up the classpath). All of the documented configuration properties from the Turbine 1 wiki apply. The only difference is that the turbine.instanceUrlSuffix does not need the port prepended as this is handled automatically unless turbine.instanceInsertPort=false.

[Note]Note

By default, Turbine looks for the /hystrix.stream endpoint on a registered instance by looking up its hostName and port entries in Eureka, then appending /hystrix.stream to it. +If the instance’s metadata contains management.port, it will be used instead of the port value for the /hystrix.stream endpoint. +By default, metadata entry management.port is equal to the management.port configuration property, it can be overridden though with following configuration:

eureka:
+  instance:
+    metadata-map:
+      management.port: ${management.port:8081}

The configuration key turbine.appConfig is a list of eureka serviceIds that turbine will use to lookup instances. The turbine stream is then used in the Hystrix dashboard using a url that looks like: https://my.turbine.sever:8080/turbine.stream?cluster=CLUSTERNAME (the cluster parameter can be omitted if the name is "default"). The cluster parameter must match an entry in turbine.aggregator.clusterConfig. Values returned from eureka are uppercase, thus we expect this example to work if there is an app registered with Eureka called "customers":

turbine:
+  aggregator:
+    clusterConfig: CUSTOMERS
+  appConfig: customers

If you need to customize which cluster names should be used by Turbine (you don’t want to store cluster names in +turbine.aggregator.clusterConfig configuration) provide a bean of type TurbineClustersProvider.

The clusterName can be customized by a SPEL expression in turbine.clusterNameExpression with root an instance of InstanceInfo. The default value is appName, which means that the Eureka serviceId ends up as the cluster key (i.e. the InstanceInfo for customers has an appName of "CUSTOMERS"). A different example would be turbine.clusterNameExpression=aSGName, which would get the cluster name from the AWS ASG name. Another example:

turbine:
+  aggregator:
+    clusterConfig: SYSTEM,USER
+  appConfig: customers,stores,ui,admin
+  clusterNameExpression: metadata['cluster']

In this case, the cluster name from 4 services is pulled from their metadata map, and is expected to have values that include "SYSTEM" and "USER".

To use the "default" cluster for all apps you need a string literal expression (with single quotes, and escaped with double quotes if it is in YAML as well):

turbine:
+  appConfig: customers,stores
+  clusterNameExpression: "'default'"

Spring Cloud provides a spring-cloud-starter-netflix-turbine that has all the dependencies you need to get a Turbine server running. Just create a Spring Boot application and annotate it with @EnableTurbine.

[Note]Note

by default Spring Cloud allows Turbine to use the host and port to allow multiple processes per host, per cluster. If you want the native Netflix behaviour built into Turbine that does not allow multiple processes per host, per cluster (the key to the instance id is the hostname), then set the property turbine.combineHostPort=false.

15.3 Turbine Stream

In some environments (e.g. in a PaaS setting), the classic Turbine model of pulling metrics from all the distributed Hystrix commands doesn’t work. In that case you might want to have your Hystrix commands push metrics to Turbine, and Spring Cloud enables that with messaging. All you need to do on the client is add a dependency to spring-cloud-netflix-hystrix-stream and the spring-cloud-starter-stream-* of your choice (see Spring Cloud Stream documentation for details on the brokers, and how to configure the client credentials, but it should work out of the box for a local broker).

On the server side Just create a Spring Boot application and annotate it with @EnableTurbineStream and by default it will come up on port 8989 (point your Hystrix dashboard to that port, any path). You can customize the port using either server.port or turbine.stream.port. If you have spring-boot-starter-web and spring-boot-starter-actuator on the classpath as well, then you can open up the Actuator endpoints on a separate port (with Tomcat by default) by providing a management.port which is different.

You can then point the Hystrix Dashboard to the Turbine Stream Server instead of individual Hystrix streams. If Turbine Stream is running on port 8989 on myhost, then put http://myhost:8989 in the stream input field in the Hystrix Dashboard. Circuits will be prefixed by their respective serviceId, followed by a dot, then the circuit name.

Spring Cloud provides a spring-cloud-starter-netflix-turbine-stream that has all the dependencies you need to get a Turbine Stream server running - just add the Stream binder of your choice, e.g. spring-cloud-starter-stream-rabbit. You need Java 8 to run the app because it is Netty-based.

Turbine Stream server also supports the cluster parameter. +Unlike Turbine server, Turbine Stream uses eureka serviceIds as cluster names and these are not configurable.

If Turbine Stream server is running on port 8989 on my.turbine.server and you have two eureka serviceIds customers and products in your environment, the following URLs will be available on your Turbine Stream server. default and empty cluster name will provide all metrics that Turbine Stream server receives.

https://my.turbine.sever:8989/turbine.stream?cluster=customers
+https://my.turbine.sever:8989/turbine.stream?cluster=products
+https://my.turbine.sever:8989/turbine.stream?cluster=default
+https://my.turbine.sever:8989/turbine.stream

So, you can use eureka serviceIds as cluster names for your Turbine dashboard (or any compatible dashboard). +You don’t need to configure any properties like turbine.appConfig, turbine.clusterNameExpression and turbine.aggregator.clusterConfig for your Turbine Stream server.

[Note]Note

Turbine Stream server gathers all metrics from the configured input channel with Spring Cloud Stream. It means that it doesn’t gather Hystrix metrics actively from each instance. It just can provide metrics that were already gathered into the input channel by each instance.

16. Client Side Load Balancer: Ribbon

Ribbon is a client side load balancer which gives you a lot of control +over the behaviour of HTTP and TCP clients. Feign already uses Ribbon, +so if you are using @FeignClient then this section also applies.

A central concept in Ribbon is that of the named client. Each load +balancer is part of an ensemble of components that work together to +contact a remote server on demand, and the ensemble has a name that +you give it as an application developer (e.g. using the @FeignClient +annotation). Spring Cloud creates a new ensemble as an +ApplicationContext on demand for each named client using +RibbonClientConfiguration. This contains (amongst other things) an +ILoadBalancer, a RestClient, and a ServerListFilter.

16.1 How to Include Ribbon

To include Ribbon in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-ribbon. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

16.2 Customizing the Ribbon Client

You can configure some bits of a Ribbon client using external +properties in <client>.ribbon.*, which is no different than using +the Netflix APIs natively, except that you can use Spring Boot +configuration files. The native options can +be inspected as static fields in CommonClientConfigKey (part of +ribbon-core).

Spring Cloud also lets you take full control of the client by +declaring additional configuration (on top of the +RibbonClientConfiguration) using @RibbonClient. Example:

@Configuration
+@RibbonClient(name = "foo", configuration = FooConfiguration.class)
+public class TestConfiguration {
+}

In this case the client is composed from the components already in +RibbonClientConfiguration together with any in FooConfiguration +(where the latter generally will override the former).

[Warning]Warning

The FooConfiguration has to be @Configuration but take +care that it is not in a @ComponentScan for the main application +context, otherwise it will be shared by all the @RibbonClients. If +you use @ComponentScan (or @SpringBootApplication) you need to +take steps to avoid it being included (for instance put it in a +separate, non-overlapping package, or specify the packages to scan +explicitly in the @ComponentScan).

Spring Cloud Netflix provides the following beans by default for ribbon +(BeanType beanName: ClassName):

  • IClientConfig ribbonClientConfig: DefaultClientConfigImpl
  • IRule ribbonRule: ZoneAvoidanceRule
  • IPing ribbonPing: DummyPing
  • ServerList<Server> ribbonServerList: ConfigurationBasedServerList
  • ServerListFilter<Server> ribbonServerListFilter: ZonePreferenceServerListFilter
  • ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
  • ServerListUpdater ribbonServerListUpdater: PollingServerListUpdater

Creating a bean of one of those type and placing it in a @RibbonClient +configuration (such as FooConfiguration above) allows you to override each +one of the beans described. Example:

@Configuration
+protected static class FooConfiguration {
+	@Bean
+	public ZonePreferenceServerListFilter serverListFilter() {
+		ZonePreferenceServerListFilter filter = new ZonePreferenceServerListFilter();
+		filter.setZone("myTestZone");
+		return filter;
+	}
+
+	@Bean
+	public IPing ribbonPing() {
+		return new PingUrl();
+	}
+}

This replaces the NoOpPing with PingUrl and provides a custom serverListFilter

16.3 Customizing default for all Ribbon Clients

A default configuration can be provided for all Ribbon Clients using the @RibbonClients annotation and registering a default configuration as shown in the following example:

@RibbonClients(defaultConfiguration = DefaultRibbonConfig.class)
+public class RibbonClientDefaultConfigurationTestsConfig {
+
+	public static class BazServiceList extends ConfigurationBasedServerList {
+		public BazServiceList(IClientConfig config) {
+			super.initWithNiwsConfig(config);
+		}
+	}
+}
+
+@Configuration
+class DefaultRibbonConfig {
+
+	@Bean
+	public IRule ribbonRule() {
+		return new BestAvailableRule();
+	}
+
+	@Bean
+	public IPing ribbonPing() {
+		return new PingUrl();
+	}
+
+	@Bean
+	public ServerList<Server> ribbonServerList(IClientConfig config) {
+		return new RibbonClientDefaultConfigurationTestsConfig.BazServiceList(config);
+	}
+
+	@Bean
+	public ServerListSubsetFilter serverListFilter() {
+		ServerListSubsetFilter filter = new ServerListSubsetFilter();
+		return filter;
+	}
+
+}

16.4 Customizing the Ribbon Client using properties

Starting with version 1.2.0, Spring Cloud Netflix now supports customizing Ribbon clients using properties to be compatible with the Ribbon documentation.

This allows you to change behavior at start up time in different environments.

The supported properties are listed below and should be prefixed by <clientName>.ribbon.:

  • NFLoadBalancerClassName: should implement ILoadBalancer
  • NFLoadBalancerRuleClassName: should implement IRule
  • NFLoadBalancerPingClassName: should implement IPing
  • NIWSServerListClassName: should implement ServerList
  • NIWSServerListFilterClassName should implement ServerListFilter
[Note]Note

Classes defined in these properties have precedence over beans defined using @RibbonClient(configuration=MyRibbonConfig.class) and the defaults provided by Spring Cloud Netflix.

To set the IRule for a service name users you could set the following:

application.yml.  +

users:
+  ribbon:
+    NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList
+    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.WeightedResponseTimeRule

+

See the Ribbon documentation for implementations provided by Ribbon.

16.5 Using Ribbon with Eureka

When Eureka is used in conjunction with Ribbon (i.e., both are on the classpath) the ribbonServerList +is overridden with an extension of DiscoveryEnabledNIWSServerList +which populates the list of servers from Eureka. It also replaces the +IPing interface with NIWSDiscoveryPing which delegates to Eureka +to determine if a server is up. The ServerList that is installed by +default is a DomainExtractingServerList and the purpose of this is +to make physical metadata available to the load balancer without using +AWS AMI metadata (which is what Netflix relies on). By default the +server list will be constructed with "zone" information as provided in +the instance metadata (so on the remote clients set +eureka.instance.metadataMap.zone), and if that is missing it can use +the domain name from the server hostname as a proxy for zone (if the +flag approximateZoneFromHostname is set). Once the zone information +is available it can be used in a ServerListFilter. By default it +will be used to locate a server in the same zone as the client because +the default is a ZonePreferenceServerListFilter. The zone of the +client is determined the same way as the remote instances by default, +i.e. via eureka.instance.metadataMap.zone.

[Note]Note

The orthodox "archaius" way to set the client zone is via a +configuration property called "@zone", and Spring Cloud will use that +in preference to all other settings if it is available (note that the +key will have to be quoted in YAML configuration).

[Note]Note

If there is no other source of zone data then a guess is made +based on the client configuration (as opposed to the instance +configuration). We take eureka.client.availabilityZones, which is a +map from region name to a list of zones, and pull out the first zone +for the instance’s own region (i.e. the eureka.client.region, which +defaults to "us-east-1" for comatibility with native Netflix).

16.6 Example: How to Use Ribbon Without Eureka

Eureka is a convenient way to abstract the discovery of remote servers +so you don’t have to hard code their URLs in clients, but if you +prefer not to use it, Ribbon and Feign are still quite +amenable. Suppose you have declared a @RibbonClient for "stores", +and Eureka is not in use (and not even on the classpath). The Ribbon +client defaults to a configured server list, and you can supply the +configuration like this

application.yml.  +

stores:
+  ribbon:
+    listOfServers: example.com,google.com

+

16.7 Example: Disable Eureka use in Ribbon

Setting the property ribbon.eureka.enabled = false will explicitly +disable the use of Eureka in Ribbon.

application.yml.  +

ribbon:
+  eureka:
+   enabled: false

+

16.8 Using the Ribbon API Directly

You can also use the LoadBalancerClient directly. Example:

public class MyClass {
+    @Autowired
+    private LoadBalancerClient loadBalancer;
+
+    public void doStuff() {
+        ServiceInstance instance = loadBalancer.choose("stores");
+        URI storesUri = URI.create(String.format("http://%s:%s", instance.getHost(), instance.getPort()));
+        // ... do something with the URI
+    }
+}

16.9 Caching of Ribbon Configuration

Each Ribbon named client has a corresponding child Application Context that Spring Cloud maintains, this application context is lazily loaded up on the first request to the named client. +This lazy loading behavior can be changed to instead eagerly load up these child Application contexts at startup by specifying the names of the Ribbon clients.

application.yml.  +

ribbon:
+  eager-load:
+    enabled: true
+    clients: client1, client2, client3

+

16.10 How to Configure Hystrix thread pools

If you change zuul.ribbonIsolationStrategy to THREAD, the thread isolation strategy for Hystrix will be used for all routes. In this case, the HystrixThreadPoolKey is set to "RibbonCommand" as default. It means that HystrixCommands for all routes will be executed in the same Hystrix thread pool. This behavior can be changed using the following configuration and it will result in HystrixCommands being executed in the Hystrix thread pool for each route.

application.yml.  +

zuul:
+  threadPool:
+    useSeparateThreadPools: true

+

The default HystrixThreadPoolKey in this case is same with service ID for each route. To add a prefix to HystrixThreadPoolKey, set zuul.threadPool.threadPoolKeyPrefix to a value that you want to add. For example:

application.yml.  +

zuul:
+  threadPool:
+    useSeparateThreadPools: true
+    threadPoolKeyPrefix: zuulgw

+

16.11 How to Provide a Key to Ribbon’s IRule

If you need to provide your own IRule implementation to handle a special routing requirement like a canary test, +you probably want to pass some information to the choose method of IRule.

com.netflix.loadbalancer.IRule.java.  +

public interface IRule{
+    public Server choose(Object key);
+         :

+

You can provide some information that will be used to choose a target server by your IRule implementation like +the following:

RequestContext.getCurrentContext()
+              .set(FilterConstants.LOAD_BALANCER_KEY, "canary-test");

If you put any object into the RequestContext with a key FilterConstants.LOAD_BALANCER_KEY, it will +be passed to the choose method of IRule implementation. Above code must be executed before RibbonRoutingFilter +is executed and Zuul’s pre filter is the best place to do that. You can easily access HTTP headers and query parameters +via RequestContext in pre filter, so it can be used to determine LOAD_BALANCER_KEY that will be passed to Ribbon. +If you don’t put any value with LOAD_BALANCER_KEY in RequestContext, null will be passed as a parameter of choose +method.

17. Declarative REST Client: Feign

Feign is a declarative web service client. It makes writing web service clients easier. To use Feign create an interface and annotate it. It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders. Spring Cloud adds support for Spring MVC annotations and for using the same HttpMessageConverters used by default in Spring Web. Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign.

17.1 How to Include Feign

To include Feign in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-openfeign. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

Example spring boot app

@Configuration
+@ComponentScan
+@EnableAutoConfiguration
+@EnableFeignClients
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}

StoreClient.java.  +

@FeignClient("stores")
+public interface StoreClient {
+    @RequestMapping(method = RequestMethod.GET, value = "/stores")
+    List<Store> getStores();
+
+    @RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
+    Store update(@PathVariable("storeId") Long storeId, Store store);
+}

+

In the @FeignClient annotation the String value ("stores" above) is +an arbitrary client name, which is used to create a Ribbon load +balancer (see below for details of Ribbon +support). You can also specify a URL using the url attribute +(absolute value or just a hostname). The name of the bean in the +application context is the fully qualified name of the interface. +To specify your own alias value you can use the qualifier value +of the @FeignClient annotation.

The Ribbon client above will want to discover the physical addresses +for the "stores" service. If your application is a Eureka client then +it will resolve the service in the Eureka service registry. If you +don’t want to use Eureka, you can simply configure a list of servers +in your external configuration (see +above for example).

17.2 Overriding Feign Defaults

A central concept in Spring Cloud’s Feign support is that of the named client. Each feign client is part of an ensemble of components that work together to contact a remote server on demand, and the ensemble has a name that you give it as an application developer using the @FeignClient annotation. Spring Cloud creates a new ensemble as an +ApplicationContext on demand for each named client using FeignClientsConfiguration. This contains (amongst other things) an feign.Decoder, a feign.Encoder, and a feign.Contract.

Spring Cloud lets you take full control of the feign client by declaring additional configuration (on top of the FeignClientsConfiguration) using @FeignClient. Example:

@FeignClient(name = "stores", configuration = FooConfiguration.class)
+public interface StoreClient {
+    //..
+}

In this case the client is composed from the components already in FeignClientsConfiguration together with any in FooConfiguration (where the latter will override the former).

[Note]Note

FooConfiguration does not need to be annotated with @Configuration. However, if it is, then take care to exclude it from any @ComponentScan that would otherwise include this configuration as it will become the default source for feign.Decoder, feign.Encoder, feign.Contract, etc., when specified. This can be avoided by putting it in a separate, non-overlapping package from any @ComponentScan or @SpringBootApplication, or it can be explicitly excluded in @ComponentScan.

[Note]Note

The serviceId attribute is now deprecated in favor of the name attribute.

[Warning]Warning

Previously, using the url attribute, did not require the name attribute. Using name is now required.

Placeholders are supported in the name and url attributes.

@FeignClient(name = "${feign.name}", url = "${feign.url}")
+public interface StoreClient {
+    //..
+}

Spring Cloud Netflix provides the following beans by default for feign (BeanType beanName: ClassName):

  • Decoder feignDecoder: ResponseEntityDecoder (which wraps a SpringDecoder)
  • Encoder feignEncoder: SpringEncoder
  • Logger feignLogger: Slf4jLogger
  • Contract feignContract: SpringMvcContract
  • Feign.Builder feignBuilder: HystrixFeign.Builder
  • Client feignClient: if Ribbon is enabled it is a LoadBalancerFeignClient, otherwise the default feign client is used.

The OkHttpClient and ApacheHttpClient feign clients can be used by setting feign.okhttp.enabled or feign.httpclient.enabled to true, respectively, and having them on the classpath. +You can customize the HTTP client used by providing a bean of either ClosableHttpClient when using Apache or OkHttpClient whe using OK HTTP.

Spring Cloud Netflix does not provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client:

  • Logger.Level
  • Retryer
  • ErrorDecoder
  • Request.Options
  • Collection<RequestInterceptor>
  • SetterFactory

Creating a bean of one of those type and placing it in a @FeignClient configuration (such as FooConfiguration above) allows you to override each one of the beans described. Example:

@Configuration
+public class FooConfiguration {
+    @Bean
+    public Contract feignContract() {
+        return new feign.Contract.Default();
+    }
+
+    @Bean
+    public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
+        return new BasicAuthRequestInterceptor("user", "password");
+    }
+}

This replaces the SpringMvcContract with feign.Contract.Default and adds a RequestInterceptor to the collection of RequestInterceptor.

@FeignClient also can be configured using configuration properties.

application.yml

feign:
+  client:
+    config:
+      feignName:
+        connectTimeout: 5000
+        readTimeout: 5000
+        loggerLevel: full
+        errorDecoder: com.example.SimpleErrorDecoder
+        retryer: com.example.SimpleRetryer
+        requestInterceptors:
+          - com.example.FooRequestInterceptor
+          - com.example.BarRequestInterceptor
+        decode404: false

Default configurations can be specified in the @EnableFeignClients attribute defaultConfiguration in a similar manner as described above. The difference is that this configuration will apply to all feign clients.

If you prefer using configuration properties to configured all @FeignClient, you can create configuration properties with default feign name.

application.yml

feign:
+  client:
+    config:
+      default:
+        connectTimeout: 5000
+        readTimeout: 5000
+        loggerLevel: basic

If we create both @Configuration bean and configuration properties, configuration properties will win. +It will override @Configuration values. But if you want to change the priority to @Configuration, +you can change feign.client.default-to-properties to false.

[Note]Note

If you need to use ThreadLocal bound variables in your RequestInterceptor`s you will need to either set the +thread isolation strategy for Hystrix to `SEMAPHORE or disable Hystrix in Feign.

application.yml

# To disable Hystrix in Feign
+feign:
+  hystrix:
+    enabled: false
+
+# To set thread isolation to SEMAPHORE
+hystrix:
+  command:
+    default:
+      execution:
+        isolation:
+          strategy: SEMAPHORE

17.3 Creating Feign Clients Manually

In some cases it might be necessary to customize your Feign Clients in a way that is not +possible using the methods above. In this case you can create Clients using the +Feign Builder API. Below is an example +which creates two Feign Clients with the same interface but configures each one with +a separate request interceptor.

@Import(FeignClientsConfiguration.class)
+class FooController {
+
+	private FooClient fooClient;
+
+	private FooClient adminClient;
+
+    	@Autowired
+	public FooController(
+			Decoder decoder, Encoder encoder, Client client) {
+		this.fooClient = Feign.builder().client(client)
+				.encoder(encoder)
+				.decoder(decoder)
+				.requestInterceptor(new BasicAuthRequestInterceptor("user", "user"))
+				.target(FooClient.class, "http://PROD-SVC");
+		this.adminClient = Feign.builder().client(client)
+				.encoder(encoder)
+				.decoder(decoder)
+				.requestInterceptor(new BasicAuthRequestInterceptor("admin", "admin"))
+				.target(FooClient.class, "http://PROD-SVC");
+    }
+}
[Note]Note

In the above example FeignClientsConfiguration.class is the default configuration +provided by Spring Cloud Netflix.

[Note]Note

PROD-SVC is the name of the service the Clients will be making requests to.

17.4 Feign Hystrix Support

If Hystrix is on the classpath and feign.hystrix.enabled=true, Feign will wrap all methods with a circuit breaker. Returning a com.netflix.hystrix.HystrixCommand is also available. This lets you use reactive patterns (with a call to .toObservable() or .observe() or asynchronous use (with a call to .queue()).

To disable Hystrix support on a per-client basis create a vanilla Feign.Builder with the "prototype" scope, e.g.:

@Configuration
+public class FooConfiguration {
+    	@Bean
+	@Scope("prototype")
+	public Feign.Builder feignBuilder() {
+		return Feign.builder();
+	}
+}
[Warning]Warning

Prior to the Spring Cloud Dalston release, if Hystrix was on the classpath Feign would have wrapped +all methods in a circuit breaker by default. This default behavior was changed in Spring Cloud Dalston in +favor for an opt-in approach.

17.5 Feign Hystrix Fallbacks

Hystrix supports the notion of a fallback: a default code path that is executed when they circuit is open or there is an error. To enable fallbacks for a given @FeignClient set the fallback attribute to the class name that implements the fallback. You also need to declare your implementation as a Spring bean.

@FeignClient(name = "hello", fallback = HystrixClientFallback.class)
+protected interface HystrixClient {
+    @RequestMapping(method = RequestMethod.GET, value = "/hello")
+    Hello iFailSometimes();
+}
+
+static class HystrixClientFallback implements HystrixClient {
+    @Override
+    public Hello iFailSometimes() {
+        return new Hello("fallback");
+    }
+}

If one needs access to the cause that made the fallback trigger, one can use the fallbackFactory attribute inside @FeignClient.

@FeignClient(name = "hello", fallbackFactory = HystrixClientFallbackFactory.class)
+protected interface HystrixClient {
+	@RequestMapping(method = RequestMethod.GET, value = "/hello")
+	Hello iFailSometimes();
+}
+
+@Component
+static class HystrixClientFallbackFactory implements FallbackFactory<HystrixClient> {
+	@Override
+	public HystrixClient create(Throwable cause) {
+		return new HystrixClient() {
+			@Override
+			public Hello iFailSometimes() {
+				return new Hello("fallback; reason was: " + cause.getMessage());
+			}
+		};
+	}
+}
[Warning]Warning

There is a limitation with the implementation of fallbacks in Feign and how Hystrix fallbacks work. Fallbacks are currently not supported for methods that return com.netflix.hystrix.HystrixCommand and rx.Observable.

17.6 Feign and @Primary

When using Feign with Hystrix fallbacks, there are multiple beans in the ApplicationContext of the same type. This will cause @Autowired to not work because there isn’t exactly one bean, or one marked as primary. To work around this, Spring Cloud Netflix marks all Feign instances as @Primary, so Spring Framework will know which bean to inject. In some cases, this may not be desirable. To turn off this behavior set the primary attribute of @FeignClient to false.

@FeignClient(name = "hello", primary = false)
+public interface HelloClient {
+	// methods here
+}

17.7 Feign Inheritance Support

Feign supports boilerplate apis via single-inheritance interfaces. +This allows grouping common operations into convenient base interfaces.

UserService.java.  +

public interface UserService {
+
+    @RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
+    User getUser(@PathVariable("id") long id);
+}

+

UserResource.java.  +

@RestController
+public class UserResource implements UserService {
+
+}

+

UserClient.java.  +

package project.user;
+
+@FeignClient("users")
+public interface UserClient extends UserService {
+
+}

+

[Note]Note

It is generally not advisable to share an interface between a +server and a client. It introduces tight coupling, and also actually +doesn’t work with Spring MVC in its current form (method parameter +mapping is not inherited).

17.8 Feign request/response compression

You may consider enabling the request or response GZIP compression for your +Feign requests. You can do this by enabling one of the properties:

feign.compression.request.enabled=true
+feign.compression.response.enabled=true

Feign request compression gives you settings similar to what you may set for your web server:

feign.compression.request.enabled=true
+feign.compression.request.mime-types=text/xml,application/xml,application/json
+feign.compression.request.min-request-size=2048

These properties allow you to be selective about the compressed media types and minimum request threshold length.

17.9 Feign logging

A logger is created for each Feign client created. By default the name of the logger is the full class name of the interface used to create the Feign client. Feign logging only responds to the DEBUG level.

application.yml.  +

logging.level.project.user.UserClient: DEBUG

+

The Logger.Level object that you may configure per client, tells Feign how much to log. Choices are:

  • NONE, No logging (DEFAULT).
  • BASIC, Log only the request method and URL and the response status code and execution time.
  • HEADERS, Log the basic information along with request and response headers.
  • FULL, Log the headers, body, and metadata for both requests and responses.

For example, the following would set the Logger.Level to FULL:

@Configuration
+public class FooConfiguration {
+    @Bean
+    Logger.Level feignLoggerLevel() {
+        return Logger.Level.FULL;
+    }
+}

18. External Configuration: Archaius

Archaius is the Netflix client side configuration library. It is the library used by all of the Netflix OSS components for configuration. Archaius is an extension of the Apache Commons Configuration project. It allows updates to configuration by either polling a source for changes or for a source to push changes to the client. Archaius uses Dynamic<Type>Property classes as handles to properties.

Archaius Example.  +

class ArchaiusTest {
+    DynamicStringProperty myprop = DynamicPropertyFactory
+            .getInstance()
+            .getStringProperty("my.prop");
+
+    void doSomething() {
+        OtherClass.someMethod(myprop.get());
+    }
+}

+

Archaius has its own set of configuration files and loading priorities. Spring applications should generally not use Archaius directly, but the need to configure the Netflix tools natively remains. Spring Cloud has a Spring Environment Bridge so Archaius can read properties from the Spring Environment. This allows Spring Boot projects to use the normal configuration toolchain, while allowing them to configure the Netflix tools, for the most part, as documented.

19. Router and Filter: Zuul

Routing in an integral part of a microservice architecture. For example, / may be mapped to your web application, /api/users is mapped to the user service and /api/shop is mapped to the shop service. Zuul is a JVM based router and server side load balancer by Netflix.

Netflix uses Zuul for the following:

  • Authentication
  • Insights
  • Stress Testing
  • Canary Testing
  • Dynamic Routing
  • Service Migration
  • Load Shedding
  • Security
  • Static Response handling
  • Active/Active traffic management

Zuul’s rule engine allows rules and filters to be written in essentially any JVM language, with built in support for Java and Groovy.

[Note]Note

The configuration property zuul.max.host.connections has been replaced by two new properties, zuul.host.maxTotalConnections and zuul.host.maxPerRouteConnections which default to 200 and 20 respectively.

[Note]Note

Default Hystrix isolation pattern (ExecutionIsolationStrategy) for all routes is SEMAPHORE. zuul.ribbonIsolationStrategy can be changed to THREAD if this isolation pattern is preferred.

19.1 How to Include Zuul

To include Zuul in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-zuul. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train.

19.2 Embedded Zuul Reverse Proxy

Spring Cloud has created an embedded Zuul proxy to ease the +development of a very common use case where a UI application wants to +proxy calls to one or more back end services. This feature is useful +for a user interface to proxy to the backend services it requires, +avoiding the need to manage CORS and authentication concerns +independently for all the backends.

To enable it, annotate a Spring Boot main class with +@EnableZuulProxy, and this forwards local calls to the appropriate +service. By convention, a service with the ID "users", will +receive requests from the proxy located at /users (with the prefix +stripped). The proxy uses Ribbon to locate an instance to forward to +via discovery, and all requests are executed in a +hystrix command, so +failures will show up in Hystrix metrics, and once the circuit is open +the proxy will not try to contact the service.

[Note]Note

the Zuul starter does not include a discovery client, so for +routes based on service IDs you need to provide one of those +on the classpath as well (e.g. Eureka is one choice).

To skip having a service automatically added, set +zuul.ignored-services to a list of service id patterns. If a service +matches a pattern that is ignored, but also included in the explicitly +configured routes map, then it will be unignored. Example:

application.yml.  +

 zuul:
+  ignoredServices: '*'
+  routes:
+    users: /myusers/**

+

In this example, all services are ignored except "users".

To augment or change +the proxy routes, you can add external configuration like the +following:

application.yml.  +

 zuul:
+  routes:
+    users: /myusers/**

+

This means that http calls to "/myusers" get forwarded to the "users" +service (for example "/myusers/101" is forwarded to "/101").

To get more fine-grained control over a route you can specify the path +and the serviceId independently:

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      serviceId: users_service

+

This means that http calls to "/myusers" get forwarded to the +"users_service" service. The route has to have a "path" which can be +specified as an ant-style pattern, so "/myusers/*" only matches one +level, but "/myusers/**" matches hierarchically.

The location of the backend can be specified as either a "serviceId" +(for a service from discovery) or a "url" (for a physical location), e.g.

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      url: https://example.com/users_service

+

These simple url-routes don’t get executed as a HystrixCommand nor do they loadbalance multiple URLs with Ribbon. +To achieve this, you can specify a serviceId with a static list of servers:

application.yml.  +

zuul:
+  routes:
+    echo:
+      path: /myusers/**
+      serviceId: myusers-service
+      stripPrefix: true
+
+hystrix:
+  command:
+    myusers-service:
+      execution:
+        isolation:
+          thread:
+            timeoutInMilliseconds: ...
+
+myusers-service:
+  ribbon:
+    NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList
+    listOfServers: https://example1.com,http://example2.com
+    ConnectTimeout: 1000
+    ReadTimeout: 3000
+    MaxTotalHttpConnections: 500
+    MaxConnectionsPerHost: 100

+

Another method is specifiying a service-route and configure a Ribbon client for the +serviceId (this requires disabling Eureka support in Ribbon: +see above for more information), e.g.

application.yml.  +

zuul:
+  routes:
+    users:
+      path: /myusers/**
+      serviceId: users
+
+ribbon:
+  eureka:
+    enabled: false
+
+users:
+  ribbon:
+    listOfServers: example.com,google.com

+

You can provide convention between serviceId and routes using +regexmapper. It uses regular expression named groups to extract +variables from serviceId and inject them into a route pattern.

ApplicationConfiguration.java.  +

@Bean
+public PatternServiceRouteMapper serviceRouteMapper() {
+    return new PatternServiceRouteMapper(
+        "(?<name>^.+)-(?<version>v.+$)",
+        "${version}/${name}");
+}

+

This means that a serviceId "myusers-v1" will be mapped to route +"/v1/myusers/**". Any regular expression is accepted but all named +groups must be present in both servicePattern and routePattern. If +servicePattern does not match a serviceId, the default behavior is +used. In the example above, a serviceId "myusers" will be mapped to route +"/myusers/**" (no version detected) This feature is disabled by +default and only applies to discovered services.

To add a prefix to all mappings, set zuul.prefix to a value, such as +/api. The proxy prefix is stripped from the request before the +request is forwarded by default (switch this behaviour off with +zuul.stripPrefix=false). You can also switch off the stripping of +the service-specific prefix from individual routes, e.g.

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      stripPrefix: false

+

[Note]Note

zuul.stripPrefix only applies to the prefix set in zuul.prefix. It does not have any effect on prefixes +defined within a given route’s path.

In this example, requests to "/myusers/101" will be forwarded to "/myusers/101" on the "users" service.

The zuul.routes entries actually bind to an object of type ZuulProperties. If you +look at the properties of that object you will see that it also has a "retryable" flag. +Set that flag to "true" to have the Ribbon client automatically retry failed requests +(and if you need to you can modify the parameters of the retry operations using +the Ribbon client configuration).

The X-Forwarded-Host header is added to the forwarded requests by +default. To turn it off set zuul.addProxyHeaders = false. The +prefix path is stripped by default, and the request to the backend +picks up a header "X-Forwarded-Prefix" ("/myusers" in the examples +above).

An application with @EnableZuulProxy could act as a standalone +server if you set a default route ("/"), for example zuul.route.home: +/ would route all traffic (i.e. "/**") to the "home" service.

If more fine-grained ignoring is needed, you can specify specific patterns to ignore. +These patterns are evaluated at the start of the route location process, which +means prefixes should be included in the pattern to warrant a match. Ignored patterns +span all services and supersede any other route specification.

application.yml.  +

 zuul:
+  ignoredPatterns: /**/admin/**
+  routes:
+    users: /myusers/**

+

This means that all calls such as "/myusers/101" will be forwarded to "/101" on the "users" service. +But calls including "/admin/" will not resolve.

[Warning]Warning

If you need your routes to have their order preserved you need to use a YAML +file as the ordering will be lost using a properties file. For example:

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+    legacy:
+      path: /**

+

If you were to use a properties file, the legacy path may end up in front of the users +path rendering the users path unreachable.

19.3 Zuul Http Client

The default HTTP client used by zuul is now backed by the Apache HTTP Client instead of the +deprecated Ribbon RestClient. To use RestClient or to use the okhttp3.OkHttpClient set +ribbon.restclient.enabled=true or ribbon.okhttp.enabled=true respectively. If you would +like to customize the Apache HTTP client or the OK HTTP client provide a bean of type +ClosableHttpClient or OkHttpClient.

19.4 Cookies and Sensitive Headers

It’s OK to share headers between services in the same system, but you +probably don’t want sensitive headers leaking downstream into external +servers. You can specify a list of ignored headers as part of the +route configuration. Cookies play a special role because they have +well-defined semantics in browsers, and they are always to be treated +as sensitive. If the consumer of your proxy is a browser, then cookies +for downstream services also cause problems for the user because they +all get jumbled up (all downstream services look like they come from +the same place).

If you are careful with the design of your services, for example if +only one of the downstream services sets cookies, then you might be +able to let them flow from the backend all the way up to the +caller. Also, if your proxy sets cookies and all your back end +services are part of the same system, it can be natural to simply +share them (and for instance use Spring Session to link them up to some +shared state). Other than that, any cookies that get set by downstream +services are likely to be not very useful to the caller, so it is +recommended that you make (at least) "Set-Cookie" and "Cookie" into +sensitive headers for routes that are not part of your domain. Even +for routes that are part of your domain, try to think carefully +about what it means before allowing cookies to flow between them and +the proxy.

The sensitive headers can be configured as a comma-separated list per +route, e.g.

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      sensitiveHeaders: Cookie,Set-Cookie,Authorization
+      url: https://downstream

+

[Note]Note

this is the default value for sensitiveHeaders, so you don’t +need to set it unless you want it to be different. N.B. this is new in +Spring Cloud Netflix 1.1 (in 1.0 the user had no control over headers +and all cookies flow in both directions).

The sensitiveHeaders are a blacklist and the default is not empty, +so to make Zuul send all headers (except the "ignored" ones) you would +have to explicitly set it to the empty list. This is necessary if you +want to pass cookie or authorization headers to your back end. Example:

application.yml.  +

 zuul:
+  routes:
+    users:
+      path: /myusers/**
+      sensitiveHeaders:
+      url: https://downstream

+

Sensitive headers can also be set globally by setting zuul.sensitiveHeaders. If sensitiveHeaders is set on a route, this will override the global sensitiveHeaders setting.

19.5 Ignored Headers

In addition to the per-route sensitive headers, you can set a global +value for zuul.ignoredHeaders for values that should be discarded +(both request and response) during interactions with downstream +services. By default these are empty, if Spring Security is not on the +classpath, and otherwise they are initialized to a set of well-known +"security" headers (e.g. involving caching) as specified by Spring +Security. The assumption in this case is that the downstream services +might add these headers too, and we want the values from the proxy. +To not discard these well known security headers in case Spring Security is on the classpath you can set zuul.ignoreSecurityHeaders to false. This can be useful if you disabled the HTTP Security response headers in Spring Security and want the values provided by downstream services

19.6 Management Endpoints

If you are using @EnableZuulProxy with the Spring Boot Actuator you +will enable (by default) two additional endpoints:

  • Routes
  • Filters

19.6.1 Routes Endpoint

A GET to the routes endpoint at /routes will return a list of the mapped +routes:

GET /routes.  +

{
+  /stores/**: "http://localhost:8081"
+}

+

Additional route details can be requested by adding the ?format=details query +string to /routes. This will produce the following output:

GET /routes?format=details.  +

{
+  "/stores/**": {
+    "id": "stores",
+    "fullPath": "/stores/**",
+    "location": "http://localhost:8081",
+    "path": "/**",
+    "prefix": "/stores",
+    "retryable": false,
+    "customSensitiveHeaders": false,
+    "prefixStripped": true
+  }
+}

+

A POST will force a refresh of the existing routes (e.g. in +case there have been changes in the service catalog). You can disable +this endpoint by setting endpoints.routes.enabled to false.

[Note]Note

the routes should respond automatically to changes in the +service catalog, but the POST to /routes is a way to force the change +to happen immediately.

19.6.2 Filters Endpoint

A GET to the filters endpoint at /filters will return a map of Zuul +filters by type. For each filter type in the map, you will find a list +of all the filters of that type, along with their details.

19.7 Strangulation Patterns and Local Forwards

A common pattern when migrating an existing application or API is to +"strangle" old endpoints, slowly replacing them with different +implementations. The Zuul proxy is a useful tool for this because you +can use it to handle all traffic from clients of the old endpoints, +but redirect some of the requests to new ones.

Example configuration:

application.yml.  +

 zuul:
+  routes:
+    first:
+      path: /first/**
+      url: https://first.example.com
+    second:
+      path: /second/**
+      url: forward:/second
+    third:
+      path: /third/**
+      url: forward:/3rd
+    legacy:
+      path: /**
+      url: https://legacy.example.com

+

In this example we are strangling the "legacy" app which is mapped to +all requests that do not match one of the other patterns. Paths in +/first/** have been extracted into a new service with an external +URL. And paths in /second/** are forwarded so they can be handled +locally, e.g. with a normal Spring @RequestMapping. Paths in +/third/** are also forwarded, but with a different prefix +(i.e. /third/foo is forwarded to /3rd/foo).

[Note]Note

The ignored patterns aren’t completely ignored, they just +aren’t handled by the proxy (so they are also effectively forwarded +locally).

19.8 Uploading Files through Zuul

If you @EnableZuulProxy you can use the proxy paths to +upload files and it should just work as long as the files +are small. For large files there is an alternative path +which bypasses the Spring DispatcherServlet (to +avoid multipart processing) in "/zuul/*". I.e. if +zuul.routes.customers=/customers/** then you can +POST large files to "/zuul/customers/*". The servlet +path is externalized via zuul.servletPath. Extremely +large files will also require elevated timeout settings +if the proxy route takes you through a Ribbon load +balancer, e.g.

application.yml.  +

hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 60000
+ribbon:
+  ConnectTimeout: 3000
+  ReadTimeout: 60000

+

Note that for streaming to work with large files, you need to use chunked encoding in the request (which some browsers +do not do by default). E.g. on the command line:

$ curl -v -H "Transfer-Encoding: chunked" \
+    -F "file=@mylarge.iso" localhost:9999/zuul/simple/file

19.9 Query String Encoding

When processing the incoming request, query params are decoded so they can be available for possible modifications in +Zuul filters. They are then re-encoded when building the backend request in the route filters. The result +can be different than the original input if it was encoded using Javascript’s encodeURIComponent() method for example. +While this causes no issues in most cases, some web servers can be picky with the encoding of complex query string.

To force the original encoding of the query string, it is possible to pass a special flag to ZuulProperties so +that the query string is taken as is with the HttpServletRequest::getQueryString method :

application.yml.  +

 zuul:
+  forceOriginalQueryStringEncoding: true

+

Note: This special flag only works with SimpleHostRoutingFilter and you loose the ability to easily override +query parameters with RequestContext.getCurrentContext().setRequestQueryParams(someOverriddenParameters) since +the query string is now fetched directly on the original HttpServletRequest.

19.10 Plain Embedded Zuul

You can also run a Zuul server without the proxying, or switch on parts of the proxying platform selectively, if you +use @EnableZuulServer (instead of @EnableZuulProxy). Any beans that you add to the application of type ZuulFilter +will be installed automatically, as they are with @EnableZuulProxy, but without any of the proxy filters being added +automatically.

In this case the routes into the Zuul server are still specified by +configuring "zuul.routes.*", but there is no service +discovery and no proxying, so the "serviceId" and "url" settings are +ignored. For example:

application.yml.  +

 zuul:
+  routes:
+    api: /api/**

+

maps all paths in "/api/**" to the Zuul filter chain.

19.11 Disable Zuul Filters

Zuul for Spring Cloud comes with a number of ZuulFilter beans enabled by default +in both proxy and server mode. See the zuul filters package for the +possible filters that are enabled. If you want to disable one, simply set +zuul.<SimpleClassName>.<filterType>.disable=true. By convention, the package after +filters is the Zuul filter type. For example to disable +org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter set +zuul.SendResponseFilter.post.disable=true.

19.12 Providing Hystrix Fallbacks For Routes

When a circuit for a given route in Zuul is tripped you can provide a fallback response +by creating a bean of type ZuulFallbackProvider. Within this bean you need to specify +the route ID the fallback is for and provide a ClientHttpResponse to return +as a fallback. Here is a very simple ZuulFallbackProvider implementation.

class MyFallbackProvider implements ZuulFallbackProvider {
+    @Override
+    public String getRoute() {
+        return "customers";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return HttpStatus.OK;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return 200;
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return "OK";
+            }
+
+            @Override
+            public void close() {
+
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}

And here is what the route configuration would look like.

zuul:
+  routes:
+    customers: /customers/**

If you would like to provide a default fallback for all routes than you can create a bean of +type ZuulFallbackProvider and have the getRoute method return * or null.

class MyFallbackProvider implements ZuulFallbackProvider {
+    @Override
+    public String getRoute() {
+        return "*";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return HttpStatus.OK;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return 200;
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return "OK";
+            }
+
+            @Override
+            public void close() {
+
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}

If you would like to choose the response based on the cause of the failure use FallbackProvider which will replace ZuulFallbackProvder in future versions.

class MyFallbackProvider implements FallbackProvider {
+
+    @Override
+    public String getRoute() {
+        return "*";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse(final Throwable cause) {
+        if (cause instanceof HystrixTimeoutException) {
+            return response(HttpStatus.GATEWAY_TIMEOUT);
+        } else {
+            return fallbackResponse();
+        }
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return response(HttpStatus.INTERNAL_SERVER_ERROR);
+    }
+
+    private ClientHttpResponse response(final HttpStatus status) {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return status;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return status.value();
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return status.getReasonPhrase();
+            }
+
+            @Override
+            public void close() {
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}

19.13 Zuul Timeouts

19.13.1 Service Discovery Configuration

If Zuul is using service discovery there are two timeouts you need to be concerned +with, the Hystrix timeout (since all routes are wrapped in Hystrix commands by default) +and the Ribbon timeout. The Hystrix timeout needs to take into account the Ribbon +read and connect timeout PLUS the total number of retries that will happen for that +service. By default Spring Cloud Zuul will do its best to calculate the Hystrix timeout +for you UNLESS you specify the Hystrix timeout explicitly.

The Hystrix timeout is calculated using the following formula:

(ribbon.ConnectTimeout + ribbon.ReadTimeout) * (ribbon.MaxAutoRetries + 1) * (ribbon.MaxAutoRetriesNextServer + 1)

As an example, if you set the following properties in your application properties

application.yml.  +

ribbon:
+  ReadTimeout:100
+  ConnectTimeout:500
+  MaxAutoRetries:1
+  MaxAutoRetriesNextServer:1

+

Then the Hystrix timeout (for all routes in this case) will be set to 2400ms.

[Note]Note

You can configure the Hystrix timeout for individual routes using service.ribbon.* properties.

[Note]Note

If you choose to not configure the above properties than the default values will be used therefore the +default Hystrix timeout will be set to 4000ms.

If you set hystrix.command.commandKey.execution.isolation.thread.timeoutInMilliseconds, where +commandKey is the route id, or set hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds +than these values will be used for the Hystrix timeout regardless of what you have set for the ribbon.* properties. +If you set either of these properties YOU are responsible for making sure it takes +into account the Ribbon connect and read timeouts as well as any retries that may happen.

19.13.2 URL Configuration

If you have configured Zuul routes by specifying URLs than you will need to use +zuul.host.connect-timeout-millis and zuul.host.socket-timeout-millis.

19.14 Rewriting Location header

If Zuul is fronting a web application then there may be a need to re-write the Location header when the web application redirects through a http status code of 3XX, otherwise the browser will end up redirecting to the web application’s url instead of the Zuul url. +A LocationRewriteFilter Zuul filter can be configured to re-write the Location header to the Zuul’s url, it also adds back the stripped global and route specific prefixes. The filter can be added the following way via a Spring Configuration file:

import org.springframework.cloud.netflix.zuul.filters.post.LocationRewriteFilter;
+...
+
+@Configuration
+@EnableZuulProxy
+public class ZuulConfig {
+    @Bean
+    public LocationRewriteFilter locationRewriteFilter() {
+        return new LocationRewriteFilter();
+    }
+}
[Warning]Warning

Use this filter with caution though, the filter acts on the Location header of ALL 3XX response codes which may not be appropriate in all scenarios, say if the user is redirecting to an external URL.

19.15 Zuul Developer Guide

For a general overview of how Zuul works, please see the Zuul Wiki.

19.15.1 The Zuul Servlet

Zuul is implemented as a Servlet. For the general cases, Zuul is embedded into the Spring Dispatch mechanism. This allows Spring MVC to be in control of the routing. In this case, Zuul is configured to buffer requests. If there is a need to go through Zuul without buffering requests (e.g. for large file uploads), the Servlet is also installed outside of the Spring Dispatcher. By default, this is located at /zuul. This path can be changed with the zuul.servlet-path property.

19.15.2 Zuul RequestContext

To pass information between filters, Zuul uses a RequestContext. Its data is held in a ThreadLocal specific to each request. Information about where to route requests, errors and the actual HttpServletRequest and HttpServletResponse are stored there. The RequestContext extends ConcurrentHashMap, so anything can be stored in the context. FilterConstants contains the keys that are used by the filters installed by Spring Cloud Netflix (more on these later).

19.15.3 @EnableZuulProxy vs. @EnableZuulServer

Spring Cloud Netflix installs a number of filters based on which annotation was used to enable Zuul. @EnableZuulProxy is a superset of @EnableZuulServer. In other words, @EnableZuulProxy contains all filters installed by @EnableZuulServer. The additional filters in the "proxy" enable routing functionality. If you want a "blank" Zuul, you should use @EnableZuulServer.

19.15.4 @EnableZuulServer Filters

Creates a SimpleRouteLocator that loads route definitions from Spring Boot configuration files.

The following filters are installed (as normal Spring Beans):

Pre filters:

  • ServletDetectionFilter: Detects if the request is through the Spring Dispatcher. Sets boolean with key FilterConstants.IS_DISPATCHER_SERVLET_REQUEST_KEY.
  • FormBodyWrapperFilter: Parses form data and reencodes it for downstream requests.
  • DebugFilter: if the debug request parameter is set, this filter sets RequestContext.setDebugRouting() and RequestContext.setDebugRequest() to true.

Route filters:

  • SendForwardFilter: This filter forwards requests using the Servlet RequestDispatcher. The forwarding location is stored in the RequestContext attribute FilterConstants.FORWARD_TO_KEY. This is useful for forwarding to endpoints in the current application.

Post filters:

  • SendResponseFilter: Writes responses from proxied requests to the current response.

Error filters:

  • SendErrorFilter: Forwards to /error (by default) if RequestContext.getThrowable() is not null. The default forwarding path (/error) can be changed by setting the error.path property.

19.15.5 @EnableZuulProxy Filters

Creates a DiscoveryClientRouteLocator that loads route definitions from a DiscoveryClient (like Eureka), as well as from properties. A route is created for each serviceId from the DiscoveryClient. As new services are added, the routes will be refreshed.

In addition to the filters described above, the following filters are installed (as normal Spring Beans):

Pre filters:

  • PreDecorationFilter: This filter determines where and how to route based on the supplied RouteLocator. It also sets various proxy-related headers for downstream requests.

Route filters:

  • RibbonRoutingFilter: This filter uses Ribbon, Hystrix and pluggable HTTP clients to send requests. Service ids are found in the RequestContext attribute FilterConstants.SERVICE_ID_KEY. This filter can use different HTTP clients. They are:

    • Apache HttpClient. This is the default client.
    • Squareup OkHttpClient v3. This is enabled by having the com.squareup.okhttp3:okhttp library on the classpath and setting ribbon.okhttp.enabled=true.
    • Netflix Ribbon HTTP client. This is enabled by setting ribbon.restclient.enabled=true. This client has limitations, such as it doesn’t support the PATCH method, but also has built-in retry.
  • SimpleHostRoutingFilter: This filter sends requests to predetermined URLs via an Apache HttpClient. URLs are found in RequestContext.getRouteHost().

19.15.6 Custom Zuul Filter examples

Most of the following "How to Write" examples below are included Sample Zuul Filters project. There are also examples of manipulating the request or response body in that repository.

19.15.7 How to Write a Pre Filter

Pre filters are used to set up data in the RequestContext for use in filters downstream. The main use case is to set information required for route filters.

public class QueryParamPreFilter extends ZuulFilter {
+	@Override
+	public int filterOrder() {
+		return PRE_DECORATION_FILTER_ORDER - 1; // run before PreDecoration
+	}
+
+	@Override
+	public String filterType() {
+		return PRE_TYPE;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		RequestContext ctx = RequestContext.getCurrentContext();
+		return !ctx.containsKey(FORWARD_TO_KEY) // a filter has already forwarded
+				&& !ctx.containsKey(SERVICE_ID_KEY); // a filter has already determined serviceId
+	}
+    @Override
+    public Object run() {
+        RequestContext ctx = RequestContext.getCurrentContext();
+		HttpServletRequest request = ctx.getRequest();
+		if (request.getParameter("foo") != null) {
+		    // put the serviceId in `RequestContext`
+    		ctx.put(SERVICE_ID_KEY, request.getParameter("foo"));
+    	}
+        return null;
+    }
+}

The filter above populates SERVICE_ID_KEY from the foo request parameter. In reality, it’s not a good idea to do that kind of direct mapping, but the service id should be looked up from the value of foo instead.

Now that SERVICE_ID_KEY is populated, PreDecorationFilter won’t run and RibbonRoutingFilter will. If you wanted to route to a full URL instead, call ctx.setRouteHost(url) instead.

To modify the path that routing filters will forward to, set the REQUEST_URI_KEY.

19.15.8 How to Write a Route Filter

Route filters are run after pre filters and are used to make requests to other services. Much of the work here is to translate request and response data to and from the client required model.

public class OkHttpRoutingFilter extends ZuulFilter {
+	@Autowired
+	private ProxyRequestHelper helper;
+
+	@Override
+	public String filterType() {
+		return ROUTE_TYPE;
+	}
+
+	@Override
+	public int filterOrder() {
+		return SIMPLE_HOST_ROUTING_FILTER_ORDER - 1;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		return RequestContext.getCurrentContext().getRouteHost() != null
+				&& RequestContext.getCurrentContext().sendZuulResponse();
+	}
+
+    @Override
+    public Object run() {
+		OkHttpClient httpClient = new OkHttpClient.Builder()
+				// customize
+				.build();
+
+		RequestContext context = RequestContext.getCurrentContext();
+		HttpServletRequest request = context.getRequest();
+
+		String method = request.getMethod();
+
+		String uri = this.helper.buildZuulRequestURI(request);
+
+		Headers.Builder headers = new Headers.Builder();
+		Enumeration<String> headerNames = request.getHeaderNames();
+		while (headerNames.hasMoreElements()) {
+			String name = headerNames.nextElement();
+			Enumeration<String> values = request.getHeaders(name);
+
+			while (values.hasMoreElements()) {
+				String value = values.nextElement();
+				headers.add(name, value);
+			}
+		}
+
+		InputStream inputStream = request.getInputStream();
+
+		RequestBody requestBody = null;
+		if (inputStream != null && HttpMethod.permitsRequestBody(method)) {
+			MediaType mediaType = null;
+			if (headers.get("Content-Type") != null) {
+				mediaType = MediaType.parse(headers.get("Content-Type"));
+			}
+			requestBody = RequestBody.create(mediaType, StreamUtils.copyToByteArray(inputStream));
+		}
+
+		Request.Builder builder = new Request.Builder()
+				.headers(headers.build())
+				.url(uri)
+				.method(method, requestBody);
+
+		Response response = httpClient.newCall(builder.build()).execute();
+
+		LinkedMultiValueMap<String, String> responseHeaders = new LinkedMultiValueMap<>();
+
+		for (Map.Entry<String, List<String>> entry : response.headers().toMultimap().entrySet()) {
+			responseHeaders.put(entry.getKey(), entry.getValue());
+		}
+
+		this.helper.setResponse(response.code(), response.body().byteStream(),
+				responseHeaders);
+		context.setRouteHost(null); // prevent SimpleHostRoutingFilter from running
+		return null;
+    }
+}

The above filter translates Servlet request information into OkHttp3 request information, executes an HTTP request, then translates OkHttp3 reponse information to the Servlet response. WARNING: this filter might have bugs and not function correctly.

19.15.9 How to Write a Post Filter

Post filters typically manipulate the response. In the filter below, we add a random UUID as the X-Foo header. Other manipulations, such as transforming the response body, are much more complex and compute-intensive.

public class AddResponseHeaderFilter extends ZuulFilter {
+	@Override
+	public String filterType() {
+		return POST_TYPE;
+	}
+
+	@Override
+	public int filterOrder() {
+		return SEND_RESPONSE_FILTER_ORDER - 1;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		return true;
+	}
+
+	@Override
+	public Object run() {
+		RequestContext context = RequestContext.getCurrentContext();
+    	HttpServletResponse servletResponse = context.getResponse();
+		servletResponse.addHeader("X-Foo", UUID.randomUUID().toString());
+		return null;
+	}
+}

19.15.10 How Zuul Errors Work

If an exception is thrown during any portion of the Zuul filter lifecycle, the error filters are executed. The SendErrorFilter is only run if RequestContext.getThrowable() is not null. It then sets specific javax.servlet.error.* attributes in the request and forwards the request to the Spring Boot error page.

19.15.11 Zuul Eager Application Context Loading

Zuul internally uses Ribbon for calling the remote url’s and Ribbon clients are by default lazily loaded up by Spring Cloud on first call. +This behavior can be changed for Zuul using the following configuration and will result in the child Ribbon related Application contexts being eagerly loaded up at application startup time.

application.yml.  +

zuul:
+  ribbon:
+    eager-load:
+      enabled: true

+

20. Polyglot support with Sidecar

Do you have non-jvm languages you want to take advantage of Eureka, Ribbon and +Config Server? The Spring Cloud Netflix Sidecar was inspired by +Netflix Prana. It includes a simple http api +to get all of the instances (ie host and port) for a given service. You can +also proxy service calls through an embedded Zuul proxy which gets its route +entries from Eureka. The Spring Cloud Config Server can be accessed directly +via host lookup or through the Zuul Proxy. The non-jvm app should implement +a health check so the Sidecar can report to eureka if the app is up or down.

To include Sidecar in your project use the dependency with group org.springframework.cloud +and artifact id spring-cloud-netflix-sidecar.

To enable the Sidecar, create a Spring Boot application with @EnableSidecar. +This annotation includes @EnableCircuitBreaker, @EnableDiscoveryClient, +and @EnableZuulProxy. Run the resulting application on the same host as the +non-jvm application.

To configure the side car add sidecar.port and sidecar.health-uri to application.yml. +The sidecar.port property is the port the non-jvm app is listening on. This +is so the Sidecar can properly register the app with Eureka. The sidecar.health-uri +is a uri accessible on the non-jvm app that mimicks a Spring Boot health +indicator. It should return a json document like the following:

health-uri-document.  +

{
+  "status":"UP"
+}

+

Here is an example application.yml for a Sidecar application:

application.yml.  +

server:
+  port: 5678
+spring:
+  application:
+    name: sidecar
+
+sidecar:
+  port: 8000
+  health-uri: http://localhost:8000/health.json

+

The api for the DiscoveryClient.getInstances() method is /hosts/{serviceId}. +Here is an example response for /hosts/customers that returns two instances on +different hosts. This api is accessible to the non-jvm app (if the sidecar is +on port 5678) at http://localhost:5678/hosts/{serviceId}.

/hosts/customers.  +

[
+    {
+        "host": "myhost",
+        "port": 9000,
+        "uri": "http://myhost:9000",
+        "serviceId": "CUSTOMERS",
+        "secure": false
+    },
+    {
+        "host": "myhost2",
+        "port": 9000,
+        "uri": "http://myhost2:9000",
+        "serviceId": "CUSTOMERS",
+        "secure": false
+    }
+]

+

The Zuul proxy automatically adds routes for each service known in eureka to +/<serviceId>, so the customers service is available at /customers. The +Non-jvm app can access the customer service via http://localhost:5678/customers +(assuming the sidecar is listening on port 5678).

If the Config Server is registered with Eureka, non-jvm application can access +it via the Zuul proxy. If the serviceId of the ConfigServer is configserver +and the Sidecar is on port 5678, then it can be accessed at +http://localhost:5678/configserver

Non-jvm app can take advantage of the Config Server’s ability to return YAML +documents. For example, a call to https://sidecar.local.spring.io:5678/configserver/default-master.yml +might result in a YAML document like the following

eureka:
+  client:
+    serviceUrl:
+      defaultZone: http://localhost:8761/eureka/
+  password: password
+info:
+  description: Spring Cloud Samples
+  url: https://github.com/spring-cloud-samples

21. RxJava with Spring MVC

Spring Cloud Netflix includes RxJava.

RxJava is a Java VM implementation of Reactive Extensions: a library for composing asynchronous and event-based programs by using observable sequences.

Spring Cloud Netflix provides support for returning rx.Single objects from Spring MVC Controllers. It also supports using rx.Observable objects for Server-sent events (SSE). This can be very convenient if your internal APIs are already built using RxJava (see Section 17.4, “Feign Hystrix Support” for examples).

Here are some examples of using rx.Single:

@RequestMapping(method = RequestMethod.GET, value = "/single")
+public Single<String> single() {
+	return Single.just("single value");
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/singleWithResponse")
+public ResponseEntity<Single<String>> singleWithResponse() {
+	return new ResponseEntity<>(Single.just("single value"),
+			HttpStatus.NOT_FOUND);
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/singleCreatedWithResponse")
+public Single<ResponseEntity<String>> singleOuterWithResponse() {
+	return Single.just(new ResponseEntity<>("single value", HttpStatus.CREATED));
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/throw")
+public Single<Object> error() {
+	return Single.error(new RuntimeException("Unexpected"));
+}

If you have an Observable, rather than a single, you can use .toSingle() or .toList().toSingle(). Here are some examples:

@RequestMapping(method = RequestMethod.GET, value = "/single")
+public Single<String> single() {
+	return Observable.just("single value").toSingle();
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/multiple")
+public Single<List<String>> multiple() {
+	return Observable.just("multiple", "values").toList().toSingle();
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/responseWithObservable")
+public ResponseEntity<Single<String>> responseWithObservable() {
+
+	Observable<String> observable = Observable.just("single value");
+	HttpHeaders headers = new HttpHeaders();
+	headers.setContentType(APPLICATION_JSON_UTF8);
+	return new ResponseEntity<>(observable.toSingle(), headers, HttpStatus.CREATED);
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/timeout")
+public Observable<String> timeout() {
+	return Observable.timer(1, TimeUnit.MINUTES).map(new Func1<Long, String>() {
+		@Override
+		public String call(Long aLong) {
+			return "single value";
+		}
+	});
+}

If you have a streaming endpoint and client, SSE could be an option. To convert rx.Observable to a Spring SseEmitter use RxResponse.sse(). Here are some examples:

@RequestMapping(method = RequestMethod.GET, value = "/sse")
+public SseEmitter single() {
+	return RxResponse.sse(Observable.just("single value"));
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/messages")
+public SseEmitter messages() {
+	return RxResponse.sse(Observable.just("message 1", "message 2", "message 3"));
+}
+
+@RequestMapping(method = RequestMethod.GET, value = "/events")
+public SseEmitter event() {
+	return RxResponse.sse(APPLICATION_JSON_UTF8,
+			Observable.just(new EventDto("Spring io", getDate(2016, 5, 19)),
+					new EventDto("SpringOnePlatform", getDate(2016, 8, 1))));
+}

22. Metrics: Spectator, Servo, and Atlas

When used together, Spectator/Servo and Atlas provide a near real-time operational insight platform.

Spectator and Servo are Netflix’s metrics collection libraries. Atlas is a Netflix metrics backend to manage dimensional time series data.

Servo served Netflix for several years and is still usable, but is gradually being phased out in favor of Spectator, which is only designed to work with Java 8. Spring Cloud Netflix provides support for both, but Java 8 based applications are encouraged to use Spectator.

To enable Servo you must set spring.metrics.servo.enabled to true.

22.1 Dimensional vs. Hierarchical Metrics

Spring Boot Actuator metrics are hierarchical and metrics are separated only by name. These names often follow a naming convention that embeds key/value attribute pairs (dimensions) into the name separated by periods. Consider the following metrics for two endpoints, root and star-star:

{
+    "counter.status.200.root": 20,
+    "counter.status.400.root": 3,
+    "counter.status.200.star-star": 5,
+}

The first metric gives us a normalized count of successful requests against the root endpoint per unit of time. But what if the system had 20 endpoints and you want to get a count of successful requests against all the endpoints? Some hierarchical metrics backends would allow you to specify a wild card such as counter.status.200.* that would read all 20 metrics and aggregate the results. Alternatively, you could provide a HandlerInterceptorAdapter that intercepts and records a metric like counter.status.200.all for all successful requests irrespective of the endpoint, but now you must write 20+1 different metrics. Similarly if you want to know the total number of successful requests for all endpoints in the service, you could specify a wild card such as counter.status.2*.*.

Even in the presence of wildcarding support on a hierarchical metrics backend, naming consistency can be difficult. Specifically the position of these tags in the name string can slip with time, breaking queries. For example, suppose we add an additional dimension to the hierarchical metrics above for HTTP method. Then counter.status.200.root becomes counter.status.200.method.get.root, etc. Our counter.status.200.* suddenly no longer has the same semantic meaning. Furthermore, if the new dimension is not applied uniformly across the codebase, certain queries may become impossible. This can quickly get out of hand.

Netflix metrics are tagged (a.k.a. dimensional). Each metric has a name, but this single named metric can contain multiple statistics and 'tag' key/value pairs that allows more querying flexibility. In fact, the statistics themselves are recorded in a special tag.

Recorded with Netflix Servo or Spectator, a timer for the root endpoint described above contains 4 statistics per status code, where the count statistic is identical to Spring Boot Actuator’s counter. In the event that we have encountered an HTTP 200 and 400 thus far, there will be 8 available data points:

{
+    "root(status=200,stastic=count)": 20,
+    "root(status=200,stastic=max)": 0.7265630630000001,
+    "root(status=200,stastic=totalOfSquares)": 0.04759702862580789,
+    "root(status=200,stastic=totalTime)": 0.2093076914666667,
+    "root(status=400,stastic=count)": 1,
+    "root(status=400,stastic=max)": 0,
+    "root(status=400,stastic=totalOfSquares)": 0,
+    "root(status=400,stastic=totalTime)": 0,
+}

22.2 Default Metrics Collection

Without any additional dependencies or configuration, a Spring Cloud based service will autoconfigure a Servo MonitorRegistry and begin collecting metrics on every Spring MVC request. By default, a Servo timer with the name rest will be recorded for each MVC request which is tagged with:

  1. HTTP method
  2. HTTP status (e.g. 200, 400, 500)
  3. URI (or "root" if the URI is empty), sanitized for Atlas
  4. The exception class name, if the request handler threw an exception
  5. The caller, if a request header with a key matching netflix.metrics.rest.callerHeader is set on the request. There is no default key for netflix.metrics.rest.callerHeader. You must add it to your application properties if you wish to collect caller information.

Set the netflix.metrics.rest.metricName property to change the name of the metric from rest to a name you provide.

If Spring AOP is enabled and org.aspectj:aspectjweaver is present on your runtime classpath, Spring Cloud will also collect metrics on every client call made with RestTemplate. A Servo timer with the name of restclient will be recorded for each MVC request which is tagged with:

  1. HTTP method
  2. HTTP status (e.g. 200, 400, 500), "CLIENT_ERROR" if the response returned null, or "IO_ERROR" if an IOException occurred during the execution of the RestTemplate method
  3. URI, sanitized for Atlas
  4. Client name
[Warning]Warning

Avoid using hardcoded url parameters within RestTemplate. When targeting dynamic endpoints use URL variables. This will avoid potential "GC Overhead Limit Reached" issues where ServoMonitorCache treats each url as a unique key.

// recommended
+String orderid = "1";
+restTemplate.getForObject("http://testclient/orders/{orderid}", String.class, orderid)
+
+// avoid
+restTemplate.getForObject("http://testclient/orders/1", String.class)

22.3 Metrics Collection: Spectator

To enable Spectator metrics, include a dependency on spring-boot-starter-spectator:

    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-starter-netflix-spectator</artifactId>
+    </dependency>

In Spectator parlance, a meter is a named, typed, and tagged configuration and a metric represents the value of a given meter at a point in time. Spectator meters are created and controlled by a registry, which currently has several different implementations. Spectator provides 4 meter types: counter, timer, gauge, and distribution summary.

Spring Cloud Spectator integration configures an injectable com.netflix.spectator.api.Registry instance for you. Specifically, it configures a ServoRegistry instance in order to unify the collection of REST metrics and the exporting of metrics to the Atlas backend under a single Servo API. Practically, this means that your code may use a mixture of Servo monitors and Spectator meters and both will be scooped up by Spring Boot Actuator MetricReader instances and both will be shipped to the Atlas backend.

22.3.1 Spectator Counter

A counter is used to measure the rate at which some event is occurring.

// create a counter with a name and a set of tags
+Counter counter = registry.counter("counterName", "tagKey1", "tagValue1", ...);
+counter.increment(); // increment when an event occurs
+counter.increment(10); // increment by a discrete amount

The counter records a single time-normalized statistic.

22.3.2 Spectator Timer

A timer is used to measure how long some event is taking. Spring Cloud automatically records timers for Spring MVC requests and conditionally RestTemplate requests, which can later be used to create dashboards for request related metrics like latency:

Figure 22.1. Request Latency

RequestLatency

// create a timer with a name and a set of tags
+Timer timer = registry.timer("timerName", "tagKey1", "tagValue1", ...);
+
+// execute an operation and time it at the same time
+T result = timer.record(() -> fooReturnsT());
+
+// alternatively, if you must manually record the time
+Long start = System.nanoTime();
+T result = fooReturnsT();
+timer.record(System.nanoTime() - start, TimeUnit.NANOSECONDS);

The timer simultaneously records 4 statistics: count, max, totalOfSquares, and totalTime. The count statistic will always match the single normalized value provided by a counter if you had called increment() once on the counter for each time you recorded a timing, so it is rarely necessary to count and time separately for a single operation.

For long running operations, Spectator provides a special LongTaskTimer.

22.3.3 Spectator Gauge

Gauges are used to determine some current value like the size of a queue or number of threads in a running state. Since gauges are sampled, they provide no information about how these values fluctuate between samples.

The normal use of a gauge involves registering the gauge once in initialization with an id, a reference to the object to be sampled, and a function to get or compute a numeric value based on the object. The reference to the object is passed in separately and the Spectator registry will keep a weak reference to the object. If the object is garbage collected, then Spectator will automatically drop the registration. See the note in Spectator’s documentation about potential memory leaks if this API is misused.

// the registry will automatically sample this gauge periodically
+registry.gauge("gaugeName", pool, Pool::numberOfRunningThreads);
+
+// manually sample a value in code at periodic intervals -- last resort!
+registry.gauge("gaugeName", Arrays.asList("tagKey1", "tagValue1", ...), 1000);

22.3.4 Spectator Distribution Summaries

A distribution summary is used to track the distribution of events. It is similar to a timer, but more general in that the size does not have to be a period of time. For example, a distribution summary could be used to measure the payload sizes of requests hitting a server.

// the registry will automatically sample this gauge periodically
+DistributionSummary ds = registry.distributionSummary("dsName", "tagKey1", "tagValue1", ...);
+ds.record(request.sizeInBytes());

22.4 Metrics Collection: Servo

[Warning]Warning

If your code is compiled on Java 8, please use Spectator instead of Servo as Spectator is destined to replace Servo entirely in the long term.

In Servo parlance, a monitor is a named, typed, and tagged configuration and a metric represents the value of a given monitor at a point in time. Servo monitors are logically equivalent to Spectator meters. Servo monitors are created and controlled by a MonitorRegistry. In spite of the above warning, Servo does have a wider array of monitor options than Spectator has meters.

Spring Cloud integration configures an injectable com.netflix.servo.MonitorRegistry instance for you. Once you have created the appropriate Monitor type in Servo, the process of recording data is wholly similar to Spectator.

22.4.1 Creating Servo Monitors

If you are using the Servo MonitorRegistry instance provided by Spring Cloud (specifically, an instance of DefaultMonitorRegistry), Servo provides convenience classes for retrieving counters and timers. These convenience classes ensure that only one Monitor is registered for each unique combination of name and tags.

To manually create a Monitor type in Servo, especially for the more exotic monitor types for which convenience methods are not provided, instantiate the appropriate type by providing a MonitorConfig instance:

MonitorConfig config = MonitorConfig.builder("timerName").withTag("tagKey1", "tagValue1").build();
+
+// somewhere we should cache this Monitor by MonitorConfig
+Timer timer = new BasicTimer(config);
+monitorRegistry.register(timer);

22.5 Metrics Backend: Atlas

Atlas was developed by Netflix to manage dimensional time series data for near real-time operational insight. Atlas features in-memory data storage, allowing it to gather and report very large numbers of metrics, very quickly.

Atlas captures operational intelligence. Whereas business intelligence is data gathered for analyzing trends over time, operational intelligence provides a picture of what is currently happening within a system.

Spring Cloud provides a spring-cloud-starter-netflix-atlas that has all the dependencies you need. Then just annotate your Spring Boot application with @EnableAtlas and provide a location for your running Atlas server with the netflix.atlas.uri property.

22.5.1 Global tags

Spring Cloud enables you to add tags to every metric sent to the Atlas backend. Global tags can be used to separate metrics by application name, environment, region, etc.

Each bean implementing AtlasTagProvider will contribute to the global tag list:

@Bean
+AtlasTagProvider atlasCommonTags(
+    @Value("${spring.application.name}") String appName) {
+  return () -> Collections.singletonMap("app", appName);
+}

22.5.2 Using Atlas

To bootstrap a in-memory standalone Atlas instance:

$ curl -LO https://github.com/Netflix/atlas/releases/download/v1.4.2/atlas-1.4.2-standalone.jar
+$ java -jar atlas-1.4.2-standalone.jar
[Tip]Tip

An Atlas standalone node running on an r3.2xlarge (61GB RAM) can handle roughly 2 million metrics per minute for a given 6 hour window.

Once running and you have collected a handful of metrics, verify that your setup is correct by listing tags on the Atlas server:

$ curl http://ATLAS/api/v1/tags
[Tip]Tip

After executing several requests against your service, you can gather some very basic information on the request latency of every request by pasting the following url in your browser: http://ATLAS/api/v1/graph?q=name,rest,:eq,:avg

The Atlas wiki contains a compilation of sample queries for various scenarios.

Make sure to check out the alerting philosophy and docs on using double exponential smoothing to generate dynamic alert thresholds.

22.6 Retrying Failed Requests

Spring Cloud Netflix offers a variety of ways to make HTTP requests. You can use a load balanced +RestTemplate, Ribbon, or Feign. No matter how you choose to your HTTP requests, there is always +a chance the request may fail. When a request fails you may want to have the request retried +automatically. To accomplish this when using Sping Cloud Netflix you need to include +Spring Retry on your application’s classpath. +When Spring Retry is present load balanced RestTemplates, Feign, and Zuul will automatically +retry any failed requests (assuming you configuration allows it to).

22.6.1 BackOff Policies

By default no backoff policy is used when retrying requests. If you would like to configure +a backoff policy you will need to create a bean of type LoadBalancedBackOffPolicyFactory +which will be used to create a BackOffPolicy for a given service.

@Configuration
+public class MyConfiguration {
+    @Bean
+    LoadBalancedBackOffPolicyFactory backOffPolciyFactory() {
+        return new LoadBalancedBackOffPolicyFactory() {
+            @Override
+            public BackOffPolicy createBackOffPolicy(String service) {
+                return new ExponentialBackOffPolicy();
+            }
+        };
+    }
+}

22.6.2 Configuration

Anytime Ribbon is used with Spring Retry you can control the retry functionality by configuring +certain Ribbon properties. The properties you can use are +client.ribbon.MaxAutoRetries, client.ribbon.MaxAutoRetriesNextServer, and +client.ribbon.OkToRetryOnAllOperations. See the Ribbon documentation +for a description of what there properties do.

[Warning]Warning

Enabling client.ribbon.OkToRetryOnAllOperations includes retring POST requests wich can have a impact +on the server’s resources due to the buffering of the request’s body.

In addition you may want to retry requests when certain status codes are returned in the +response. You can list the response codes you would like the Ribbon client to retry using the + property clientName.ribbon.retryableStatusCodes. For example

clientName:
+  ribbon:
+    retryableStatusCodes: 404,502

You can also create a bean of type LoadBalancedRetryPolicy and implement the retryableStatusCode +method to determine whether you want to retry a request given the status code.

22.6.3 Zuul

You can turn off Zuul’s retry functionality by setting zuul.retryable to false. You +can also disable retry functionality on route by route basis by setting +zuul.routes.routename.retryable to false.

23. HTTP Clients

Spring Cloud Netflix will automatically create the HTTP client used by Ribbon, Feign, and +Zuul for you. However you can also provide your own HTTP clients customized how you please +yourself. To do this you can either create a bean of type ClosableHttpClient if you +are using the Apache Http Cient, or OkHttpClient if you are using OK HTTP.

[Note]Note

When you create your own HTTP client you are also responsible for implementing +the correct connection management strategies for these clients. Doing this improperly +can result in resource management issues.

Part IV. Spring Cloud Stream

This section goes into more detail about how you can work with Spring Cloud Stream. +It covers topics such as creating and running stream applications.

24. Introducing Spring Cloud Stream

Spring Cloud Stream is a framework for building message-driven microservice applications. +Spring Cloud Stream builds upon Spring Boot to create standalone, production-grade Spring applications, and uses Spring Integration to provide connectivity to message brokers. +It provides opinionated configuration of middleware from several vendors, introducing the concepts of persistent publish-subscribe semantics, consumer groups, and partitions.

You can add the @EnableBinding annotation to your application to get immediate connectivity to a message broker, and you can add @StreamListener to a method to cause it to receive events for stream processing. +The following is a simple sink application which receives external messages.

@SpringBootApplication
+@EnableBinding(Sink.class)
+public class VoteRecordingSinkApplication {
+
+  public static void main(String[] args) {
+    SpringApplication.run(VoteRecordingSinkApplication.class, args);
+  }
+
+  @StreamListener(Sink.INPUT)
+  public void processVote(Vote vote) {
+      votingService.recordVote(vote);
+  }
+}

The @EnableBinding annotation takes one or more interfaces as parameters (in this case, the parameter is a single Sink interface). +An interface declares input and/or output channels. +Spring Cloud Stream provides the interfaces Source, Sink, and Processor; you can also define your own interfaces.

The following is the definition of the Sink interface:

public interface Sink {
+  String INPUT = "input";
+
+  @Input(Sink.INPUT)
+  SubscribableChannel input();
+}

The @Input annotation identifies an input channel, through which received messages enter the application; the @Output annotation identifies an output channel, through which published messages leave the application. +The @Input and @Output annotations can take a channel name as a parameter; if a name is not provided, the name of the annotated method will be used.

Spring Cloud Stream will create an implementation of the interface for you. +You can use this in the application by autowiring it, as in the following example of a test case.

@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = VoteRecordingSinkApplication.class)
+@WebAppConfiguration
+@DirtiesContext
+public class StreamApplicationTests {
+
+  @Autowired
+  private Sink sink;
+
+  @Test
+  public void contextLoads() {
+    assertNotNull(this.sink.input());
+  }
+}

25. Main Concepts

Spring Cloud Stream provides a number of abstractions and primitives that simplify the writing of message-driven microservice applications. +This section gives an overview of the following:

  • Spring Cloud Stream’s application model
  • The Binder abstraction
  • Persistent publish-subscribe support
  • Consumer group support
  • Partitioning support
  • A pluggable Binder API

25.1 Application Model

A Spring Cloud Stream application consists of a middleware-neutral core. +The application communicates with the outside world through input and output channels injected into it by Spring Cloud Stream. +Channels are connected to external brokers through middleware-specific Binder implementations.

Figure 25.1. Spring Cloud Stream Application

SCSt with binder

25.1.1 Fat JAR

Spring Cloud Stream applications can be run in standalone mode from your IDE for testing. +To run a Spring Cloud Stream application in production, you can create an executable (or "fat") JAR by using the standard Spring Boot tooling provided for Maven or Gradle.

25.2 The Binder Abstraction

Spring Cloud Stream provides Binder implementations for Kafka and Rabbit MQ. +Spring Cloud Stream also includes a TestSupportBinder, which leaves a channel unmodified so that tests can interact with channels directly and reliably assert on what is received. +You can use the extensible API to write your own Binder.

Spring Cloud Stream uses Spring Boot for configuration, and the Binder abstraction makes it possible for a Spring Cloud Stream application to be flexible in how it connects to middleware. +For example, deployers can dynamically choose, at runtime, the destinations (e.g., the Kafka topics or RabbitMQ exchanges) to which channels connect. +Such configuration can be provided through external configuration properties and in any form supported by Spring Boot (including application arguments, environment variables, and application.yml or application.properties files). +In the sink example from the Chapter 24, Introducing Spring Cloud Stream section, setting the application property spring.cloud.stream.bindings.input.destination to raw-sensor-data will cause it to read from the raw-sensor-data Kafka topic, or from a queue bound to the raw-sensor-data RabbitMQ exchange.

Spring Cloud Stream automatically detects and uses a binder found on the classpath. +You can easily use different types of middleware with the same code: just include a different binder at build time. +For more complex use cases, you can also package multiple binders with your application and have it choose the binder, and even whether to use different binders for different channels, at runtime.

25.3 Persistent Publish-Subscribe Support

Communication between applications follows a publish-subscribe model, where data is broadcast through shared topics. +This can be seen in the following figure, which shows a typical deployment for a set of interacting Spring Cloud Stream applications.

Figure 25.2. Spring Cloud Stream Publish-Subscribe

SCSt sensors

Data reported by sensors to an HTTP endpoint is sent to a common destination named raw-sensor-data. +From the destination, it is independently processed by a microservice application that computes time-windowed averages and by another microservice application that ingests the raw data into HDFS. +In order to process the data, both applications declare the topic as their input at runtime.

The publish-subscribe communication model reduces the complexity of both the producer and the consumer, and allows new applications to be added to the topology without disruption of the existing flow. +For example, downstream from the average-calculating application, you can add an application that calculates the highest temperature values for display and monitoring. +You can then add another application that interprets the same flow of averages for fault detection. +Doing all communication through shared topics rather than point-to-point queues reduces coupling between microservices.

While the concept of publish-subscribe messaging is not new, Spring Cloud Stream takes the extra step of making it an opinionated choice for its application model. +By using native middleware support, Spring Cloud Stream also simplifies use of the publish-subscribe model across different platforms.

25.4 Consumer Groups

While the publish-subscribe model makes it easy to connect applications through shared topics, the ability to scale up by creating multiple instances of a given application is equally important. +When doing this, different instances of an application are placed in a competing consumer relationship, where only one of the instances is expected to handle a given message.

Spring Cloud Stream models this behavior through the concept of a consumer group. +(Spring Cloud Stream consumer groups are similar to and inspired by Kafka consumer groups.) +Each consumer binding can use the spring.cloud.stream.bindings.<channelName>.group property to specify a group name. +For the consumers shown in the following figure, this property would be set as spring.cloud.stream.bindings.<channelName>.group=hdfsWrite or spring.cloud.stream.bindings.<channelName>.group=average.

Figure 25.3. Spring Cloud Stream Consumer Groups

SCSt groups

All groups which subscribe to a given destination receive a copy of published data, but only one member of each group receives a given message from that destination. +By default, when a group is not specified, Spring Cloud Stream assigns the application to an anonymous and independent single-member consumer group that is in a publish-subscribe relationship with all other consumer groups.

25.4.1 Durability

Consistent with the opinionated application model of Spring Cloud Stream, consumer group subscriptions are durable. +That is, a binder implementation ensures that group subscriptions are persistent, and once at least one subscription for a group has been created, the group will receive messages, even if they are sent while all applications in the group are stopped.

[Note]Note

Anonymous subscriptions are non-durable by nature. +For some binder implementations (e.g., RabbitMQ), it is possible to have non-durable group subscriptions.

In general, it is preferable to always specify a consumer group when binding an application to a given destination. +When scaling up a Spring Cloud Stream application, you must specify a consumer group for each of its input bindings. +This prevents the application’s instances from receiving duplicate messages (unless that behavior is desired, which is unusual).

25.5 Partitioning Support

Spring Cloud Stream provides support for partitioning data between multiple instances of a given application. +In a partitioned scenario, the physical communication medium (e.g., the broker topic) is viewed as being structured into multiple partitions. +One or more producer application instances send data to multiple consumer application instances and ensure that data identified by common characteristics are processed by the same consumer instance.

Spring Cloud Stream provides a common abstraction for implementing partitioned processing use cases in a uniform fashion. +Partitioning can thus be used whether the broker itself is naturally partitioned (e.g., Kafka) or not (e.g., RabbitMQ).

Figure 25.4. Spring Cloud Stream Partitioning

SCSt partitioning

Partitioning is a critical concept in stateful processing, where it is critiical, for either performance or consistency reasons, to ensure that all related data is processed together. +For example, in the time-windowed average calculation example, it is important that all measurements from any given sensor are processed by the same application instance.

[Note]Note

To set up a partitioned processing scenario, you must configure both the data-producing and the data-consuming ends.

26. Programming Model

This section describes Spring Cloud Stream’s programming model. +Spring Cloud Stream provides a number of predefined annotations for declaring bound input and output channels as well as how to listen to channels.

26.1 Declaring and Binding Channels

26.1.1 Triggering Binding Via @EnableBinding

You can turn a Spring application into a Spring Cloud Stream application by applying the @EnableBinding annotation to one of the application’s configuration classes. +The @EnableBinding annotation itself is meta-annotated with @Configuration and triggers the configuration of Spring Cloud Stream infrastructure:

...
+@Import(...)
+@Configuration
+@EnableIntegration
+public @interface EnableBinding {
+    ...
+    Class<?>[] value() default {};
+}

The @EnableBinding annotation can take as parameters one or more interface classes that contain methods which represent bindable components (typically message channels).

[Note]Note

The @EnableBinding annotation is only required on your Configuration classes, you can provide as many binding interfaces as you need, for instance: @EnableBinding(value={Orders.class, Payment.class}. +Where both Order and Payment interfaces would declare @Input and @Output channels.

26.1.2 @Input and @Output

A Spring Cloud Stream application can have an arbitrary number of input and output channels defined in an interface as @Input and @Output methods:

public interface Barista {
+
+    @Input
+    SubscribableChannel orders();
+
+    @Output
+    MessageChannel hotDrinks();
+
+    @Output
+    MessageChannel coldDrinks();
+}

Using this interface as a parameter to @EnableBinding will trigger the creation of three bound channels named orders, hotDrinks, and coldDrinks, respectively.

@EnableBinding(Barista.class)
+public class CafeConfiguration {
+
+   ...
+}
[Note]Note

In Spring Cloud Stream, the bindable MessageChannel components are the Spring Messaging MessageChannel (for outbound) and its extension SubscribableChannel (for inbound). +Using the same mechanism other bindable components can be supported. +KStream support in Spring Cloud Stream Kafka binder is one such example where KStream is used as inbound/outbound bindable components. +In this documentation, we will continue to refer to MessageChannels as the bindable components.

Customizing Channel Names

Using the @Input and @Output annotations, you can specify a customized channel name for the channel, as shown in the following example:

public interface Barista {
+    ...
+    @Input("inboundOrders")
+    SubscribableChannel orders();
+}

In this example, the created bound channel will be named inboundOrders.

Source, Sink, and Processor

For easy addressing of the most common use cases, which involve either an input channel, an output channel, or both, Spring Cloud Stream provides three predefined interfaces out of the box.

Source can be used for an application which has a single outbound channel.

public interface Source {
+
+  String OUTPUT = "output";
+
+  @Output(Source.OUTPUT)
+  MessageChannel output();
+
+}

Sink can be used for an application which has a single inbound channel.

public interface Sink {
+
+  String INPUT = "input";
+
+  @Input(Sink.INPUT)
+  SubscribableChannel input();
+
+}

Processor can be used for an application which has both an inbound channel and an outbound channel.

public interface Processor extends Source, Sink {
+}

Spring Cloud Stream provides no special handling for any of these interfaces; they are only provided out of the box.

26.1.3 Accessing Bound Channels

Injecting the Bound Interfaces

For each bound interface, Spring Cloud Stream will generate a bean that implements the interface. +Invoking a @Input-annotated or @Output-annotated method of one of these beans will return the relevant bound channel.

The bean in the following example sends a message on the output channel when its hello method is invoked. +It invokes output() on the injected Source bean to retrieve the target channel.

@Component
+public class SendingBean {
+
+    private Source source;
+
+    @Autowired
+    public SendingBean(Source source) {
+        this.source = source;
+    }
+
+    public void sayHello(String name) {
+         source.output().send(MessageBuilder.withPayload(name).build());
+    }
+}

Injecting Channels Directly

Bound channels can be also injected directly:

@Component
+public class SendingBean {
+
+    private MessageChannel output;
+
+    @Autowired
+    public SendingBean(MessageChannel output) {
+        this.output = output;
+    }
+
+    public void sayHello(String name) {
+         output.send(MessageBuilder.withPayload(name).build());
+    }
+}

If the name of the channel is customized on the declaring annotation, that name should be used instead of the method name. +Given the following declaration:

public interface CustomSource {
+    ...
+    @Output("customOutput")
+    MessageChannel output();
+}

The channel will be injected as shown in the following example:

@Component
+public class SendingBean {
+
+    private MessageChannel output;
+
+    @Autowired
+    public SendingBean(@Qualifier("customOutput") MessageChannel output) {
+        this.output = output;
+    }
+
+    public void sayHello(String name) {
+         this.output.send(MessageBuilder.withPayload(name).build());
+    }
+}

26.1.4 Producing and Consuming Messages

You can write a Spring Cloud Stream application using either Spring Integration annotations or Spring Cloud Stream’s @StreamListener annotation. +The @StreamListener annotation is modeled after other Spring Messaging annotations (such as @MessageMapping, @JmsListener, @RabbitListener, etc.) but adds content type management and type coercion features.

Native Spring Integration Support

Because Spring Cloud Stream is based on Spring Integration, Stream completely inherits Integration’s foundation and infrastructure as well as the component itself. +For example, you can attach the output channel of a Source to a MessageSource:

@EnableBinding(Source.class)
+public class TimerSource {
+
+  @Value("${format}")
+  private String format;
+
+  @Bean
+  @InboundChannelAdapter(value = Source.OUTPUT, poller = @Poller(fixedDelay = "${fixedDelay}", maxMessagesPerPoll = "1"))
+  public MessageSource<String> timerMessageSource() {
+    return () -> new GenericMessage<>(new SimpleDateFormat(format).format(new Date()));
+  }
+}

Or you can use a processor’s channels in a transformer:

@EnableBinding(Processor.class)
+public class TransformProcessor {
+  @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
+  public Object transform(String message) {
+    return message.toUpperCase();
+  }
+}
[Note]Note

It’s important to understant that when you consume from the same binding using @StreamListener a pubsub model is used, where each method annotated with @StreamListener receives it’s own copy of the message, each one has its own consumer group. +However, if you share a bindable channel as an input for @Aggregator, @Transformer or @ServiceActivator, those will consume in a competing model, no individual consumer group is created for each subscription.

Spring Integration Error Channel Support

Spring Cloud Stream supports publishing error messages received by the Spring Integration global +error channel. Error messages sent to the errorChannel can be published to a specific destination +at the broker by configuring a binding for the outbound target named error. For example, to +publish error messages to a broker destination named "myErrors", provide the following property: +spring.cloud.stream.bindings.error.destination=myErrors.

Message Channel Binders and Error Channels

Starting with version 1.3, some MessageChannel - based binders publish errors to a discrete error channel for each destination. +In addition, these error channels are bridged to the global Spring Integration errorChannel mentioned above. +You can therefore consume errors for specific destinations and/or for all destinations, using a standard Spring Integration flow (IntegrationFlow, @ServiceActivator, etc).

On the consumer side, the listener thread catches any exceptions and forwards an ErrorMessage to the destination’s error channel. +The payload of the message is a MessagingException with the normal failedMessage and cause properties. +Usually, the raw data received from the broker is included in a header. +For binders that support (and are configured with) a dead letter destination; a MessagePublishingErrorHandler is subscribed to the channel, and the raw data is forwarded to the dead letter destination.

On the producer side; for binders that support some kind of async result after publishing messages (e.g. RabbitMQ, Kafka), you can enable an error channel by setting the …​producer.errorChannelEnabled to true. +The payload of the ErrorMessage depends on the binder implementation but will be a MessagingException with the normal failedMessage property, as well as additional properties about the failure. +Refer to the binder documentation for complete details.

Using @StreamListener for Automatic Content Type Handling

Complementary to its Spring Integration support, Spring Cloud Stream provides its own @StreamListener annotation, modeled after other Spring Messaging annotations (e.g. @MessageMapping, @JmsListener, @RabbitListener, etc.). +The @StreamListener annotation provides a simpler model for handling inbound messages, especially when dealing with use cases that involve content type management and type coercion.

Spring Cloud Stream provides an extensible MessageConverter mechanism for handling data conversion by bound channels and for, in this case, dispatching to methods annotated with @StreamListener. +The following is an example of an application which processes external Vote events:

@EnableBinding(Sink.class)
+public class VoteHandler {
+
+  @Autowired
+  VotingService votingService;
+
+  @StreamListener(Sink.INPUT)
+  public void handle(Vote vote) {
+    votingService.record(vote);
+  }
+}

The distinction between @StreamListener and a Spring Integration @ServiceActivator is seen when considering an inbound Message that has a String payload and a contentType header of application/json. +In the case of @StreamListener, the MessageConverter mechanism will use the contentType header to parse the String payload into a Vote object.

As with other Spring Messaging methods, method arguments can be annotated with @Payload, @Headers and @Header.

[Note]Note

For methods which return data, you must use the @SendTo annotation to specify the output binding destination for data returned by the method:

@EnableBinding(Processor.class)
+public class TransformProcessor {
+
+  @Autowired
+  VotingService votingService;
+
+  @StreamListener(Processor.INPUT)
+  @SendTo(Processor.OUTPUT)
+  public VoteResult handle(Vote vote) {
+    return votingService.record(vote);
+  }
+}

Using @StreamListener for dispatching messages to multiple methods

Since version 1.2, Spring Cloud Stream supports dispatching messages to multiple @StreamListener methods registered on an input channel, based on a condition.

In order to be eligible to support conditional dispatching, a method must satisfy the follow conditions:

  • it must not return a value
  • it must be an individual message handling method (reactive API methods are not supported)

The condition is specified via a SpEL expression in the condition attribute of the annotation and is evaluated for each message. +All the handlers that match the condition will be invoked in the same thread and no assumption must be made about the order in which the invocations take place.

An example of using @StreamListener with dispatching conditions can be seen below. +In this example, all the messages bearing a header type with the value foo will be dispatched to the receiveFoo method, and all the messages bearing a header type with the value bar will be dispatched to the receiveBar method.

@EnableBinding(Sink.class)
+@EnableAutoConfiguration
+public static class TestPojoWithAnnotatedArguments {
+
+    @StreamListener(target = Sink.INPUT, condition = "headers['type']=='foo'")
+    public void receiveFoo(@Payload FooPojo fooPojo) {
+       // handle the message
+    }
+
+    @StreamListener(target = Sink.INPUT, condition = "headers['type']=='bar'")
+    public void receiveBar(@Payload BarPojo barPojo) {
+       // handle the message
+    }
+}
[Note]Note

Dispatching via @StreamListener conditions is only supported for handlers of individual messages, and not for reactive programming support (described below).

26.1.5 Reactive Programming Support

Spring Cloud Stream also supports the use of reactive APIs where incoming and outgoing data is handled as continuous data flows. +Support for reactive APIs is available via the spring-cloud-stream-reactive, which needs to be added explicitly to your project.

The programming model with reactive APIs is declarative, where instead of specifying how each individual message should be handled, you can use operators that describe functional transformations from inbound to outbound data flows.

Spring Cloud Stream supports the following reactive APIs:

  • Reactor
  • RxJava 1.x

In the future, it is intended to support a more generic model based on Reactive Streams.

The reactive programming model is also using the @StreamListener annotation for setting up reactive handlers. The differences are that:

  • the @StreamListener annotation must not specify an input or output, as they are provided as arguments and return values from the method;
  • the arguments of the method must be annotated with @Input and @Output indicating which input or output will the incoming and respectively outgoing data flows connect to;
  • the return value of the method, if any, will be annotated with @Output, indicating the input where data shall be sent.
[Note]Note

Reactive programming support requires Java 1.8.

[Note]Note

As of Spring Cloud Stream 1.1.1 and later (starting with release train Brooklyn.SR2), reactive programming support requires the use of Reactor 3.0.4.RELEASE and higher. +Earlier Reactor versions (including 3.0.1.RELEASE, 3.0.2.RELEASE and 3.0.3.RELEASE) are not supported. +spring-cloud-stream-reactive will transitively retrieve the proper version, but it is possible for the project structure to manage the version of the io.projectreactor:reactor-core to an earlier release, especially when using Maven. +This is the case for projects generated via Spring Initializr with Spring Boot 1.x, which will override the Reactor version to 2.0.8.RELEASE. +In such cases you must ensure that the proper version of the artifact is released. +This can be simply achieved by adding a direct dependency on io.projectreactor:reactor-core with a version of 3.0.4.RELEASE or later to your project.

[Note]Note

The use of term reactive is currently referring to the reactive APIs being used and not to the execution model being reactive (i.e. the bound endpoints are still using a 'push' rather than 'pull' model). While some backpressure support is provided by the use of Reactor, we do intend on the long run to support entirely reactive pipelines by the use of native reactive clients for the connected middleware.

Reactor-based handlers

A Reactor based handler can have the following argument types:

  • For arguments annotated with @Input, it supports the Reactor type Flux. +The parameterization of the inbound Flux follows the same rules as in the case of individual message handling: it can be the entire Message, a POJO which can be the Message payload, or a POJO which is the result of a transformation based on the Message content-type header. Multiple inputs are provided;
  • For arguments annotated with Output, it supports the type FluxSender which connects a Flux produced by the method with an output. Generally speaking, specifying outputs as arguments is only recommended when the method can have multiple outputs;

A Reactor based handler supports a return type of Flux, case in which it must be annotated with @Output. We recommend using the return value of the method when a single output flux is available.

Here is an example of a simple Reactor-based Processor.

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  @Output(Processor.OUTPUT)
+  public Flux<String> receive(@Input(Processor.INPUT) Flux<String> input) {
+    return input.map(s -> s.toUpperCase());
+  }
+}

The same processor using output arguments looks like this:

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  public void receive(@Input(Processor.INPUT) Flux<String> input,
+     @Output(Processor.OUTPUT) FluxSender output) {
+     output.send(input.map(s -> s.toUpperCase()));
+  }
+}

RxJava 1.x support

RxJava 1.x handlers follow the same rules as Reactor-based one, but will use Observable and ObservableSender arguments and return types.

So the first example above will become:

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  @Output(Processor.OUTPUT)
+  public Observable<String> receive(@Input(Processor.INPUT) Observable<String> input) {
+    return input.map(s -> s.toUpperCase());
+  }
+}

The second example above will become:

@EnableBinding(Processor.class)
+@EnableAutoConfiguration
+public static class UppercaseTransformer {
+
+  @StreamListener
+  public void receive(@Input(Processor.INPUT) Observable<String> input,
+     @Output(Processor.OUTPUT) ObservableSender output) {
+     output.send(input.map(s -> s.toUpperCase()));
+  }
+}

Reactive Sources

Spring Cloud Stream reactive support also provides the ability for creating reactive sources through the StreamEmitter annotation. +Using StreamEmitter annotation, a regular source may be converted to a reactive one. +StreamEmitter is a method level annotation that marks a method to be an emitter to outputs declared via EnableBinding. +It is not allowed to use the Input annotation along with StreamEmitter, as the methods marked with this annotation are not listening from any input, rather generating to an output. +Following the same programming model used in StreamListener, StreamEmitter also allows flexible ways of using the Output annotation depending on whether the method has any arguments, return type etc.

Here are some examples of using StreamEmitter in various styles.

The following example will emit the "Hello World" message every millisecond and publish to a Flux. +In this case, the resulting messages in Flux will be sent to the output channel of the Source.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  @Output(Source.OUTPUT)
+  public Flux<String> emit() {
+    return Flux.intervalMillis(1)
+            .map(l -> "Hello World");
+  }
+}

Following is another flavor of the same sample as above. +Instead of returning a Flux, this method uses a FluxSender to programmatically send Flux from a source.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  @Output(Source.OUTPUT)
+  public void emit(FluxSender output) {
+    output.send(Flux.intervalMillis(1)
+            .map(l -> "Hello World"));
+  }
+}

Following is exactly same as the above snippet in functionality and style. +However, instead of using an explicit Output annotation at the method level, it is used as the method parameter level.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  public void emit(@Output(Source.OUTPUT) FluxSender output) {
+    output.send(Flux.intervalMillis(1)
+            .map(l -> "Hello World"));
+  }
+}

Here is yet another flavor of writing reacting sources using the Reactive Streams Publisher API and the support for it in the Spring Integration Java DSL. +The Publisher is still using Reactor Flux under the hood, but from an application perspective, that is transparent to the user and only needs Reactive Streams and Java DSL for Spring Integration.

@EnableBinding(Source.class)
+@EnableAutoConfiguration
+public static class HelloWorldEmitter {
+
+  @StreamEmitter
+  @Output(Source.OUTPUT)
+  @Bean
+  public Publisher<Message<String>> emit() {
+    return IntegrationFlows.from(() ->
+                new GenericMessage<>("Hello World"),
+        e -> e.poller(p -> p.fixedDelay(1)))
+        .toReactivePublisher();
+  }
+}

26.1.6 Aggregation

Spring Cloud Stream provides support for aggregating multiple applications together, connecting their input and output channels directly and avoiding the additional cost of exchanging messages via a broker. +As of version 1.0 of Spring Cloud Stream, aggregation is supported only for the following types of applications:

  • sources - applications with a single output channel named output, typically having a single binding of the type org.springframework.cloud.stream.messaging.Source
  • sinks - applications with a single input channel named input, typically having a single binding of the type org.springframework.cloud.stream.messaging.Sink
  • processors - applications with a single input channel named input and a single output channel named output, typically having a single binding of the type org.springframework.cloud.stream.messaging.Processor.

They can be aggregated together by creating a sequence of interconnected applications, in which the output channel of an element in the sequence is connected to the input channel of the next element, if it exists. +A sequence can start with either a source or a processor, it can contain an arbitrary number of processors and must end with either a processor or a sink.

Depending on the nature of the starting and ending element, the sequence may have one or more bindable channels, as follows:

  • if the sequence starts with a source and ends with a sink, all communication between the applications is direct and no channels will be bound
  • if the sequence starts with a processor, then its input channel will become the input channel of the aggregate and will be bound accordingly
  • if the sequence ends with a processor, then its output channel will become the output channel of the aggregate and will be bound accordingly

Aggregation is performed using the AggregateApplicationBuilder utility class, as in the following example. +Let’s consider a project in which we have source, processor and a sink, which may be defined in the project, or may be contained in one of the project’s dependencies.

[Note]Note

Each component (source, sink or processor) in an aggregate application must be provided in a separate package if the configuration classes use @SpringBootApplication. +This is required to avoid cross-talk between applications, due to the classpath scanning performed by @SpringBootApplication on the configuration classes inside the same package. +In the example below, it can be seen that the Source, Processor and Sink application classes are grouped in separate packages. +A possible alternative is to provide the source, sink or processor configuration in a separate @Configuration class, avoid the use of @SpringBootApplication/@ComponentScan and use those for aggregation.

package com.app.mysink;
+
+@SpringBootApplication
+@EnableBinding(Sink.class)
+public class SinkApplication {
+
+	private static Logger logger = LoggerFactory.getLogger(SinkApplication.class);
+
+	@ServiceActivator(inputChannel=Sink.INPUT)
+	public void loggerSink(Object payload) {
+		logger.info("Received: " + payload);
+	}
+}
package com.app.myprocessor;
+
+// Imports omitted
+
+@SpringBootApplication
+@EnableBinding(Processor.class)
+public class ProcessorApplication {
+
+	@Transformer
+	public String loggerSink(String payload) {
+		return payload.toUpperCase();
+	}
+}
package com.app.mysource;
+
+// Imports omitted
+
+@SpringBootApplication
+@EnableBinding(Source.class)
+public class SourceApplication {
+
+	@InboundChannelAdapter(value = Source.OUTPUT)
+	public String timerMessageSource() {
+		return new SimpleDateFormat().format(new Date());
+	}
+}

Each configuration can be used for running a separate component, but in this case they can be aggregated together as follows:

package com.app;
+
+// Imports omitted
+
+@SpringBootApplication
+public class SampleAggregateApplication {
+
+	public static void main(String[] args) {
+		new AggregateApplicationBuilder()
+			.from(SourceApplication.class).args("--fixedDelay=5000")
+			.via(ProcessorApplication.class)
+			.to(SinkApplication.class).args("--debug=true").run(args);
+	}
+}

The starting component of the sequence is provided as argument to the from() method. +The ending component of the sequence is provided as argument to the to() method. +Intermediate processors are provided as argument to the via() method. +Multiple processors of the same type can be chained together (e.g. for pipelining transformations with different configurations). +For each component, the builder can provide runtime arguments for Spring Boot configuration.

Configuring aggregate application

Spring Cloud Stream supports passing properties for the individual applications inside the aggregate application using 'namespace' as prefix.

The namespace can be set for applications as follows:

@SpringBootApplication
+public class SampleAggregateApplication {
+
+	public static void main(String[] args) {
+		new AggregateApplicationBuilder()
+			.from(SourceApplication.class).namespace("source").args("--fixedDelay=5000")
+			.via(ProcessorApplication.class).namespace("processor1")
+			.to(SinkApplication.class).namespace("sink").args("--debug=true").run(args);
+	}
+}

Once the 'namespace' is set for the individual applications, the application properties with the namespace as prefix can be passed to the aggregate application using any supported property source (commandline, environment properties etc.,)

For instance, to override the default fixedDelay and debug properties of 'source' and 'sink' applications:

java -jar target/MyAggregateApplication-0.0.1-SNAPSHOT.jar --source.fixedDelay=10000 --sink.debug=false

Configuring binding service properties for non self contained aggregate application

The non self-contained aggregate application is bound to external broker via either or both the inbound/outbound components (typically, message channels) of the aggregate application while the applications inside the aggregate application are directly bound. +For example: a source application’s output and a processor application’s input are directly bound while the processor’s output channel is bound to an external destination at the broker. +When passing the binding service properties for non-self contained aggregate application, it is required to pass the binding service properties to the aggregate application instead of setting them as 'args' to individual child application. +For instance,

@SpringBootApplication
+public class SampleAggregateApplication {
+
+	public static void main(String[] args) {
+		new AggregateApplicationBuilder()
+			.from(SourceApplication.class).namespace("source").args("--fixedDelay=5000")
+			.via(ProcessorApplication.class).namespace("processor1").args("--debug=true").run(args);
+	}
+}

The binding properties like --spring.cloud.stream.bindings.output.destination=processor-output need to be specified as one of the external configuration properties (cmdline arg etc.,).

27. Binders

Spring Cloud Stream provides a Binder abstraction for use in connecting to physical destinations at the external middleware. +This section provides information about the main concepts behind the Binder SPI, its main components, and implementation-specific details.

27.1 Producers and Consumers

Figure 27.1. Producers and Consumers

producers consumers

A producer is any component that sends messages to a channel. +The channel can be bound to an external message broker via a Binder implementation for that broker. +When invoking the bindProducer() method, the first parameter is the name of the destination within the broker, the second parameter is the local channel instance to which the producer will send messages, and the third parameter contains properties (such as a partition key expression) to be used within the adapter that is created for that channel.

A consumer is any component that receives messages from a channel. +As with a producer, the consumer’s channel can be bound to an external message broker. +When invoking the bindConsumer() method, the first parameter is the destination name, and a second parameter provides the name of a logical group of consumers. +Each group that is represented by consumer bindings for a given destination receives a copy of each message that a producer sends to that destination (i.e., publish-subscribe semantics). +If there are multiple consumer instances bound using the same group name, then messages will be load-balanced across those consumer instances so that each message sent by a producer is consumed by only a single consumer instance within each group (i.e., queueing semantics).

27.2 Binder SPI

The Binder SPI consists of a number of interfaces, out-of-the box utility classes and discovery strategies that provide a pluggable mechanism for connecting to external middleware.

The key point of the SPI is the Binder interface which is a strategy for connecting inputs and outputs to external middleware.

public interface Binder<T, C extends ConsumerProperties, P extends ProducerProperties> {
+	Binding<T> bindConsumer(String name, String group, T inboundBindTarget, C consumerProperties);
+
+	Binding<T> bindProducer(String name, T outboundBindTarget, P producerProperties);
+}

The interface is parameterized, offering a number of extension points:

  • input and output bind targets - as of version 1.0, only MessageChannel is supported, but this is intended to be used as an extension point in the future;
  • extended consumer and producer properties - allowing specific Binder implementations to add supplemental properties which can be supported in a type-safe manner.

A typical binder implementation consists of the following

  • a class that implements the Binder interface;
  • a Spring @Configuration class that creates a bean of the type above along with the middleware connection infrastructure;
  • a META-INF/spring.binders file found on the classpath containing one or more binder definitions, e.g.
kafka:\
+org.springframework.cloud.stream.binder.kafka.config.KafkaBinderConfiguration

27.3 Binder Detection

Spring Cloud Stream relies on implementations of the Binder SPI to perform the task of connecting channels to message brokers. +Each Binder implementation typically connects to one type of messaging system.

27.3.1 Classpath Detection

By default, Spring Cloud Stream relies on Spring Boot’s auto-configuration to configure the binding process. +If a single Binder implementation is found on the classpath, Spring Cloud Stream will use it automatically. +For example, a Spring Cloud Stream project that aims to bind only to RabbitMQ can simply add the following dependency:

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-rabbit</artifactId>
+</dependency>

For the specific maven coordinates of other binder dependencies, please refer to the documentation of that binder implementation.

27.4 Multiple Binders on the Classpath

When multiple binders are present on the classpath, the application must indicate which binder is to be used for each channel binding. +Each binder configuration contains a META-INF/spring.binders, which is a simple properties file:

rabbit:\
+org.springframework.cloud.stream.binder.rabbit.config.RabbitServiceAutoConfiguration

Similar files exist for the other provided binder implementations (e.g., Kafka), and custom binder implementations are expected to provide them, as well. +The key represents an identifying name for the binder implementation, whereas the value is a comma-separated list of configuration classes that each contain one and only one bean definition of type org.springframework.cloud.stream.binder.Binder.

Binder selection can either be performed globally, using the spring.cloud.stream.defaultBinder property (e.g., spring.cloud.stream.defaultBinder=rabbit) or individually, by configuring the binder on each channel binding. +For instance, a processor application (that has channels with the names input and output for read/write respectively) which reads from Kafka and writes to RabbitMQ can specify the following configuration:

spring.cloud.stream.bindings.input.binder=kafka
+spring.cloud.stream.bindings.output.binder=rabbit

27.5 Connecting to Multiple Systems

By default, binders share the application’s Spring Boot auto-configuration, so that one instance of each binder found on the classpath will be created. +If your application should connect to more than one broker of the same type, you can specify multiple binder configurations, each with different environment settings.

[Note]Note

Turning on explicit binder configuration will disable the default binder configuration process altogether. +If you do this, all binders in use must be included in the configuration. +Frameworks that intend to use Spring Cloud Stream transparently may create binder configurations that can be referenced by name, but will not affect the default binder configuration. +In order to do so, a binder configuration may have its defaultCandidate flag set to false, e.g. spring.cloud.stream.binders.<configurationName>.defaultCandidate=false. +This denotes a configuration that will exist independently of the default binder configuration process.

For example, this is the typical configuration for a processor application which connects to two RabbitMQ broker instances:

spring:
+  cloud:
+    stream:
+      bindings:
+        input:
+          destination: foo
+          binder: rabbit1
+        output:
+          destination: bar
+          binder: rabbit2
+      binders:
+        rabbit1:
+          type: rabbit
+          environment:
+            spring:
+              rabbitmq:
+                host: <host1>
+        rabbit2:
+          type: rabbit
+          environment:
+            spring:
+              rabbitmq:
+                host: <host2>

27.6 Binder configuration properties

The following properties are available when creating custom binder configurations. +They must be prefixed with spring.cloud.stream.binders.<configurationName>.

type

The binder type. +It typically references one of the binders found on the classpath, in particular a key in a META-INF/spring.binders file.

By default, it has the same value as the configuration name.

inheritEnvironment

Whether the configuration will inherit the environment of the application itself.

Default true.

environment

Root for a set of properties that can be used to customize the environment of the binder. +When this is configured, the context in which the binder is being created is not a child of the application context. +This allows for complete separation between the binder components and the application components.

Default empty.

defaultCandidate

Whether the binder configuration is a candidate for being considered a default binder, or can be used only when explicitly referenced. +This allows adding binder configurations without interfering with the default processing.

Default true.

28. Configuration Options

Spring Cloud Stream supports general configuration options as well as configuration for bindings and binders. +Some binders allow additional binding properties to support middleware-specific features.

Configuration options can be provided to Spring Cloud Stream applications via any mechanism supported by Spring Boot. +This includes application arguments, environment variables, and YAML or .properties files.

28.1 Spring Cloud Stream Properties

spring.cloud.stream.instanceCount

The number of deployed instances of an application. +Must be set for partitioning and if using Kafka.

Default: 1.

spring.cloud.stream.instanceIndex
The instance index of the application: a number from 0 to instanceCount-1. +Used for partitioning and with Kafka. +Automatically set in Cloud Foundry to match the application’s instance index.
spring.cloud.stream.dynamicDestinations

A list of destinations that can be bound dynamically (for example, in a dynamic routing scenario). +If set, only listed destinations can be bound.

Default: empty (allowing any destination to be bound).

spring.cloud.stream.defaultBinder

The default binder to use, if multiple binders are configured. +See Multiple Binders on the Classpath.

Default: empty.

spring.cloud.stream.overrideCloudConnectors

This property is only applicable when the cloud profile is active and Spring Cloud Connectors are provided with the application. +If the property is false (the default), the binder will detect a suitable bound service (e.g. a RabbitMQ service bound in Cloud Foundry for the RabbitMQ binder) and will use it for creating connections (usually via Spring Cloud Connectors). +When set to true, this property instructs binders to completely ignore the bound services and rely on Spring Boot properties (e.g. relying on the spring.rabbitmq.* properties provided in the environment for the RabbitMQ binder). +The typical usage of this property is to be nested in a customized environment when connecting to multiple systems.

Default: false.

28.2 Binding Properties

Binding properties are supplied using the format spring.cloud.stream.bindings.<channelName>.<property>=<value>. +The <channelName> represents the name of the channel being configured (e.g., output for a Source).

To avoid repetition, Spring Cloud Stream supports setting values for all channels, in the format spring.cloud.stream.default.<property>=<value>.

In what follows, we indicate where we have omitted the spring.cloud.stream.bindings.<channelName>. prefix and focus just on the property name, with the understanding that the prefix will be included at runtime.

28.2.1 Properties for Use of Spring Cloud Stream

The following binding properties are available for both input and output bindings and must be prefixed with spring.cloud.stream.bindings.<channelName>., e.g. spring.cloud.stream.bindings.input.destination=ticktock.

Default values can be set by using the prefix spring.cloud.stream.default, e.g. spring.cloud.stream.default.contentType=application/json.

destination
The target destination of a channel on the bound middleware (e.g., the RabbitMQ exchange or Kafka topic). +If the channel is bound as a consumer, it could be bound to multiple destinations and the destination names can be specified as comma separated String values. +If not set, the channel name is used instead. +The default value of this property cannot be overridden.
group

The consumer group of the channel. +Applies only to inbound bindings. +See Consumer Groups.

Default: null (indicating an anonymous consumer).

contentType

The content type of the channel.

Default: null (so that no type coercion is performed).

binder

The binder used by this binding. +See Section 27.4, “Multiple Binders on the Classpath” for details.

Default: null (the default binder will be used, if one exists).

28.2.2 Consumer properties

The following binding properties are available for input bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.consumer., e.g. spring.cloud.stream.bindings.input.consumer.concurrency=3.

Default values can be set by using the prefix spring.cloud.stream.default.consumer, e.g. spring.cloud.stream.default.consumer.headerMode=raw.

concurrency

The concurrency of the inbound consumer.

Default: 1.

partitioned

Whether the consumer receives data from a partitioned producer.

Default: false.

headerMode

When set to raw, disables header parsing on input. +Effective only for messaging middleware that does not support message headers natively and requires header embedding. +Useful when inbound data is coming from outside Spring Cloud Stream applications.

Default: embeddedHeaders.

maxAttempts

If processing fails, the number of attempts to process the message (including the first). +Set to 1 to disable retry.

Default: 3.

backOffInitialInterval

The backoff initial interval on retry.

Default: 1000.

backOffMaxInterval

The maximum backoff interval.

Default: 10000.

backOffMultiplier

The backoff multiplier.

Default: 2.0.

instanceIndex

When set to a value greater than equal to zero, allows customizing the instance index of this consumer (if different from spring.cloud.stream.instanceIndex). +When set to a negative value, it will default to spring.cloud.stream.instanceIndex.

Default: -1.

instanceCount

When set to a value greater than equal to zero, allows customizing the instance count of this consumer (if different from spring.cloud.stream.instanceCount). +When set to a negative value, it will default to spring.cloud.stream.instanceCount.

Default: -1.

28.2.3 Producer Properties

The following binding properties are available for output bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.producer., e.g. spring.cloud.stream.bindings.input.producer.partitionKeyExpression=payload.id.

Default values can be set by using the prefix spring.cloud.stream.default.producer, e.g. spring.cloud.stream.default.producer.partitionKeyExpression=payload.id.

partitionKeyExpression

A SpEL expression that determines how to partition outbound data. +If set, or if partitionKeyExtractorClass is set, outbound data on this channel will be partitioned, and partitionCount must be set to a value greater than 1 to be effective. +The two options are mutually exclusive. +See Section 25.5, “Partitioning Support”.

Default: null.

partitionKeyExtractorClass

A PartitionKeyExtractorStrategy implementation. +If set, or if partitionKeyExpression is set, outbound data on this channel will be partitioned, and partitionCount must be set to a value greater than 1 to be effective. +The two options are mutually exclusive. +See Section 25.5, “Partitioning Support”.

Default: null.

partitionSelectorClass

A PartitionSelectorStrategy implementation. +Mutually exclusive with partitionSelectorExpression. +If neither is set, the partition will be selected as the hashCode(key) % partitionCount, where key is computed via either partitionKeyExpression or partitionKeyExtractorClass.

Default: null.

partitionSelectorExpression

A SpEL expression for customizing partition selection. +Mutually exclusive with partitionSelectorClass. +If neither is set, the partition will be selected as the hashCode(key) % partitionCount, where key is computed via either partitionKeyExpression or partitionKeyExtractorClass.

Default: null.

partitionCount

The number of target partitions for the data, if partitioning is enabled. +Must be + set to a value greater than 1 if the producer is partitioned. +On Kafka, interpreted as a + hint; the larger of this and the partition count of the target topic is used instead.

Default: 1.

requiredGroups
A comma-separated list of groups to which the producer must ensure message delivery even if they start after it has been created (e.g., by pre-creating durable queues in RabbitMQ).
headerMode

When set to raw, disables header embedding on output. +Effective only for messaging middleware that does not support message headers natively and requires header embedding. +Useful when producing data for non-Spring Cloud Stream applications.

Default: embeddedHeaders.

useNativeEncoding

When set to true, the outbound message is serialized directly by client library, which must be configured correspondingly (e.g. setting an appropriate Kafka producer value serializer). +When this configuration is being used, the outbound message marshalling is not based on the contentType of the binding. +When native encoding is used, it is the responsibility of the consumer to use appropriate decoder (ex: Kafka consumer value de-serializer) to deserialize the inbound message. +Also, when native encoding/decoding is used the headerMode property is ignored and headers will not be embedded into the message.

Default: false.

errorChannelEnabled

When set to true, if the binder supports async send results; send failures will be sent to an error channel for the destination. +See the section called “Message Channel Binders and Error Channels” for more information.

Default: false.

28.3 Using dynamically bound destinations

Besides the channels defined via @EnableBinding, Spring Cloud Stream allows applications to send messages to dynamically bound destinations. +This is useful, for example, when the target destination needs to be determined at runtime. +Applications can do so by using the BinderAwareChannelResolver bean, registered automatically by the @EnableBinding annotation.

The property 'spring.cloud.stream.dynamicDestinations' can be used for restricting the dynamic destination names to a set known beforehand (whitelisting). +If the property is not set, any destination can be bound dynamicaly.

The BinderAwareChannelResolver can be used directly as in the following example, in which a REST controller uses a path variable to decide the target channel.

@EnableBinding
+@Controller
+public class SourceWithDynamicDestination {
+
+	@Autowired
+	private BinderAwareChannelResolver resolver;
+
+	@RequestMapping(path = "/{target}", method = POST, consumes = "*/*")
+	@ResponseStatus(HttpStatus.ACCEPTED)
+	public void handleRequest(@RequestBody String body, @PathVariable("target") target,
+	       @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) {
+		sendMessage(body, target, contentType);
+	}
+
+	private void sendMessage(String body, String target, Object contentType) {
+		resolver.resolveDestination(target).send(MessageBuilder.createMessage(body,
+				new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType))));
+	}
+}

After starting the application on the default port 8080, when sending the following data:

curl -H "Content-Type: application/json" -X POST -d "customer-1" http://localhost:8080/customers
+
+curl -H "Content-Type: application/json" -X POST -d "order-1" http://localhost:8080/orders

The destinations 'customers' and 'orders' are created in the broker (for example: exchange in case of Rabbit or topic in case of Kafka) with the names 'customers' and 'orders', and the data is published to the appropriate destinations.

The BinderAwareChannelResolver is a general purpose Spring Integration DestinationResolver and can be injected in other components. +For example, in a router using a SpEL expression based on the target field of an incoming JSON message.

@EnableBinding
+@Controller
+public class SourceWithDynamicDestination {
+
+	@Autowired
+	private BinderAwareChannelResolver resolver;
+
+
+	@RequestMapping(path = "/", method = POST, consumes = "application/json")
+	@ResponseStatus(HttpStatus.ACCEPTED)
+	public void handleRequest(@RequestBody String body, @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) {
+		sendMessage(body, contentType);
+	}
+
+	private void sendMessage(Object body, Object contentType) {
+		routerChannel().send(MessageBuilder.createMessage(body,
+				new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType))));
+	}
+
+	@Bean(name = "routerChannel")
+	public MessageChannel routerChannel() {
+		return new DirectChannel();
+	}
+
+	@Bean
+	@ServiceActivator(inputChannel = "routerChannel")
+	public ExpressionEvaluatingRouter router() {
+        ExpressionEvaluatingRouter router =
+            new ExpressionEvaluatingRouter(new SpelExpressionParser().parseExpression("payload.target"));
+		router.setDefaultOutputChannelName("default-output");
+		router.setChannelResolver(resolver);
+		return router;
+	}
+}

29. Content Type and Transformation

To allow you to propagate information about the content type of produced messages, Spring Cloud Stream attaches, by default, a contentType header to outbound messages. +For middleware that does not directly support headers, Spring Cloud Stream provides its own mechanism of automatically wrapping outbound messages in an envelope of its own. +For middleware that does support headers, Spring Cloud Stream applications may receive messages with a given content type from non-Spring Cloud Stream applications.

Spring Cloud Stream can handle messages based on this information in two ways:

  • Through its contentType settings on inbound and outbound channels
  • Through its argument mapping performed for methods annotated with @StreamListener

Spring Cloud Stream allows you to declaratively configure type conversion for inputs and outputs using the spring.cloud.stream.bindings.<channelName>.content-type property of a binding. +Note that general type conversion may also be accomplished easily by using a transformer inside your application. +Currently, Spring Cloud Stream natively supports the following type conversions commonly used in streams:

  • JSON to/from POJO
  • JSON to/from org.springframework.tuple.Tuple
  • Object to/from byte[] : Either the raw bytes serialized for remote transport, bytes emitted by an application, or converted to bytes using Java serialization(requires the object to be Serializable)
  • String to/from byte[]
  • Object to plain text (invokes the object’s toString() method)

Where JSON represents either a byte array or String payload containing JSON. +Currently, Objects may be converted from a JSON byte array or String. +Converting to JSON always produces a String.

If no content-type property is set on an outbound channel, Spring Cloud Stream will serialize the payload using a serializer based on the Kryo serialization framework. +Deserializing messages at the destination requires the payload class to be present on the receiver’s classpath.

29.1 MIME types

content-type values are parsed as media types, e.g., application/json or text/plain;charset=UTF-8. +MIME types are especially useful for indicating how to convert to String or byte[] content. +Spring Cloud Stream also uses MIME type format to represent Java types, using the general type application/x-java-object with a type parameter. +For example, application/x-java-object;type=java.util.Map or application/x-java-object;type=com.bar.Foo can be set as the content-type property of an input binding. +In addition, Spring Cloud Stream provides custom MIME types, notably, application/x-spring-tuple to specify a Tuple.

29.2 MIME types and Java types

The type conversions Spring Cloud Stream provides out of the box are summarized in the following table: +'Source Payload' means the payload before conversion and 'Target Payload' means the 'payload' after conversion. +The type conversion can occur either on the 'producer' side (output) or at the 'consumer' side (input).

Source PayloadTarget Payloadcontent-type header (source message)content-type header (after conversion)Comments

POJO

JSON String

ignored

application/json

 

Tuple

JSON String

ignored

application/json

JSON is tailored for Tuple

POJO

String (toString())

ignored

text/plain, java.lang.String

 

POJO

byte[] (java.io serialized)

ignored

application/x-java-serialized-object

 

JSON byte[] or String

POJO

application/json (or none)

application/x-java-object

 

byte[] or String

Serializable

application/x-java-serialized-object

application/x-java-object

 

JSON byte[] or String

Tuple

application/json (or none)

application/x-spring-tuple

 

byte[]

String

any

text/plain, java.lang.String

will apply any Charset specified in the content-type header

String

byte[]

any

application/octet-stream

will apply any Charset specified in the content-type header

[Note]Note

Conversion applies to payloads that require type conversion. +For example, if an application produces an XML string with outputType=application/json, the payload will not be converted from XML to JSON. +This is because the payload send to the outbound channel is already a String so no conversion will be applied at runtime. +It is also important to note that when using the default serialization mechanism, the payload class must be shared between the sending and receiving application, and compatible with the binary content. +This can create issues when application code changes independently in the two applications, as the binary format and code may become incompatible.

[Tip]Tip

While conversion is supported for both inbound and outbound channels, it is especially recommended to be used for the conversion of outbound messages. +For the conversion of inbound messages, especially when the target is a POJO, the @StreamListener support will perform the conversion automatically.

29.3 Customizing message conversion

Besides the conversions that it supports out of the box, Spring Cloud Stream also supports registering your own message conversion implementations. +This allows you to send and receive data in a variety of custom formats, including binary, and associate them with specific contentTypes. +Spring Cloud Stream registers all the beans of type org.springframework.messaging.converter.MessageConverter as custom message converters along with the out of the box message converters.

If your message converter needs to work with a specific content-type and target class (for both input and output), then the message converter needs to extend org.springframework.messaging.converter.AbstractMessageConverter. +For conversion when using @StreamListener, a message converter that implements org.springframework.messaging.converter.MessageConverter would suffice.

Here is an example of creating a message converter bean (with the content-type application/bar) inside a Spring Cloud Stream application:

@EnableBinding(Sink.class)
+@SpringBootApplication
+public static class SinkApplication {
+
+  ...
+
+  @Bean
+  public MessageConverter customMessageConverter() {
+    return new MyCustomMessageConverter();
+  }
public class MyCustomMessageConverter extends AbstractMessageConverter {
+
+	public MyCustomMessageConverter() {
+		super(new MimeType("application", "bar"));
+	}
+
+	@Override
+  protected boolean supports(Class<?> clazz) {
+    return (Bar.class == clazz);
+  }
+
+	@Override
+	protected Object convertFromInternal(Message<?> message, Class<?> targetClass, Object conversionHint) {
+		Object payload = message.getPayload();
+		return (payload instanceof Bar ? payload : new Bar((byte[]) payload));
+	}
+}

Spring Cloud Stream also provides support for Avro-based converters and schema evolution. +See the specific section for details.

29.4 @StreamListener and Message Conversion

The @StreamListener annotation provides a convenient way for converting incoming messages without the need to specify the content type of an input channel. +During the dispatching process to methods annotated with @StreamListener, a conversion will be applied automatically if the argument requires it.

For example, let’s consider a message with the String content {"greeting":"Hello, world"} and a content-type header of application/json is received on the input channel. +Let us consider the following application that receives it:

public class GreetingMessage {
+
+  String greeting;
+
+  public String getGreeting() {
+    return greeting;
+  }
+
+  public void setGreeting(String greeting) {
+    this.greeting = greeting;
+  }
+}
+
+@EnableBinding(Sink.class)
+@EnableAutoConfiguration
+public static class GreetingSink {
+
+		@StreamListener(Sink.INPUT)
+		public void receive(Greeting greeting) {
+			// handle Greeting
+		}
+	}

The argument of the method will be populated automatically with the POJO containing the unmarshalled form of the JSON String.

30. Schema Evolution Support

Spring Cloud Stream provides support for schema evolution so that the data can be evolved over time and still work with older or newer producers and consumers and vice versa. +Most serialization models, especially the ones that aim for portability across different platforms and languages, rely on a schema that describes how the data is serialized in the binary payload. +In order to serialize the data and then to interpret it, both the sending and receiving sides must have access to a schema that describes the binary format. +In certain cases, the schema can be inferred from the payload type on serialization or from the target type on deserialization. +However, many applications benefit from having access to an explicit schema that describes the binary data format. +A schema registry lets you store schema information in a textual format (typically JSON) and makes that information accessible to various applications that need it to receive and send data in binary format. +A schema is referenceable as a tuple consisting of:

  • A subject that is the logical name of the schema
  • The schema version
  • The schema format, which describes the binary format of the data

This following sections goes through the details of various components involved in schema evolution process.

30.1 Schema Registry Client

The client-side abstraction for interacting with schema registry servers is the SchemaRegistryClient interface, which has the following structure:

public interface SchemaRegistryClient {
+
+    SchemaRegistrationResponse register(String subject, String format, String schema);
+
+    String fetch(SchemaReference schemaReference);
+
+    String fetch(Integer id);
+
+}

Spring Cloud Stream provides out-of-the-box implementations for interacting with its own schema server and for interacting with the Confluent Schema Registry.

A client for the Spring Cloud Stream schema registry can be configured by using the @EnableSchemaRegistryClient, as follows:

  @EnableBinding(Sink.class)
+  @SpringBootApplication
+  @EnableSchemaRegistryClient
+  public static class AvroSinkApplication {
+    ...
+  }
[Note]Note

The default converter is optimized to cache not only the schemas from the remote server but also the parse() and toString() methods, which are quite expensive. +Because of this, it uses a DefaultSchemaRegistryClient that does not cache responses. +If you intend to change the default behavior, you can use the client directly on your code and override it to the desired outcome. +To do so, you have to add the property spring.cloud.stream.schemaRegistryClient.cached=true to your application properties.

30.1.1 Schema Registry Client Properties

The Schema Registry Client supports the following properties:

spring.cloud.stream.schemaRegistryClient.endpoint
The location of the schema-server. +When setting this, use a full URL, including protocol (http or https) , port, and context path.
Default
http://localhost:8990/
spring.cloud.stream.schemaRegistryClient.cached
Whether the client should cache schema server responses. +Normally set to false, as the caching happens in the message converter. +Clients using the schema registry client should set this to true.
Default
true

30.2 Avro Schema Registry Client Message Converters

For applications that have a SchemaRegistryClient bean registered with the application context, Spring Cloud Stream auto configures an Apache Avro message converter for schema management. +This eases schema evolution, as applications that receive messages can get easy access to a writer schema that can be reconciled with their own reader schema.

For outbound messages, if the content type of the channel is set to application/*+avro, the MessageConverter is activated, as shown in the following example:

spring.cloud.stream.bindings.output.contentType=application/*+avro

During the outbound conversion, the message converter tries to infer the schema of each outbound messages (based on its type) and register it to a subject (based on the payload type) by using the SchemaRegistryClient. +If an identical schema is already found, then a reference to it is retrieved. +If not, the schema is registered, and a new version number is provided. +The message is sent with a contentType header by using the following scheme: application/[prefix].[subject].v[version]+avro, where prefix is configurable and subject is deduced from the payload type.

For example, a message of the type User might be sent as a binary payload with a content type of application/vnd.user.v2+avro, where user is the subject and 2 is the version number.

When receiving messages, the converter infers the schema reference from the header of the incoming message and tries to retrieve it. The schema is used as the writer schema in the deserialization process.

30.2.1 Avro Schema Registry Message Converter Properties

If you have enabled Avro based schema registry client by setting spring.cloud.stream.bindings.output.contentType=application/*+avro, you can customize the behavior of the registration by setting the following properties.

spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled

Enable if you want the converter to use reflection to infer a Schema from a POJO.

Default: false

spring.cloud.stream.schema.avro.readerSchema
Avro compares schema versions by looking at a writer schema (origin payload) and a reader schema (your application payload). See the Avro documentation for more information. If set, this overrides any lookups at the schema server and uses the local schema as the reader schema. +Default: null
spring.cloud.stream.schema.avro.schemaLocations

Registers any .avsc files listed in this property with the Schema Server.

Default: empty

spring.cloud.stream.schema.avro.prefix

The prefix to be used on the Content-Type header.

Default: vnd

30.3 Apache Avro Message Converters

Spring Cloud Stream provides support for schema-based message converters through its spring-cloud-stream-schema module. +Currently, the only serialization format supported out of the box for schema-based message converters is Apache Avro, with more formats to be added in future versions.

The spring-cloud-stream-schema module contains two types of message converters that can be used for Apache Avro serialization:

  • Converters that use the class information of the serialized or deserialized objects or a schema with a location known at startup.
  • Converters that use a schema registry. They locate the schemas at runtime and dynamically register new schemas as domain objects evolve.

30.4 Converters with Schema Support

The AvroSchemaMessageConverter supports serializing and deserializing messages either by using a predefined schema or by using the schema information available in the class (either reflectively or contained in the SpecificRecord). +If you provide a custom converter, then the default AvroSchemaMessageConverter bean is not created. The following example shows a custom converter:

To use custom converters, you can simply add it to the application context, optionally specifying one or more MimeTypes with which to associate it. +The default MimeType is application/avro.

If the target type of the conversion is a GenericRecord, a schema must be set.

The following example shows how to configure a converter in a sink application by registering the Apache Avro MessageConverter without a predefined schema. +In this example, note that the mime type value is avro/bytes, not the default application/avro.

@EnableBinding(Sink.class)
+@SpringBootApplication
+public static class SinkApplication {
+
+  ...
+
+  @Bean
+  public MessageConverter userMessageConverter() {
+      return new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes"));
+  }
+}

Conversely, the following application registers a converter with a predefined schema (found on the classpath):

@EnableBinding(Sink.class)
+@SpringBootApplication
+public static class SinkApplication {
+
+  ...
+
+  @Bean
+  public MessageConverter userMessageConverter() {
+      AvroSchemaMessageConverter converter = new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes"));
+      converter.setSchemaLocation(new ClassPathResource("schemas/User.avro"));
+      return converter;
+  }
+}

30.5 Schema Registry Server

Spring Cloud Stream provides a schema registry server implementation. +To use it, you can add the spring-cloud-stream-schema-server artifact to your project and use the @EnableSchemaRegistryServer annotation, which adds the schema registry server REST controller to your application. +This annotation is intended to be used with Spring Boot web applications, and the listening port of the server is controlled by the server.port property. +The spring.cloud.stream.schema.server.path property can be used to control the root path of the schema server (especially when it is embedded in other applications). +The spring.cloud.stream.schema.server.allowSchemaDeletion boolean property enables the deletion of a schema. By default, this is disabled.

The schema registry server uses a relational database to store the schemas. +By default, it uses an embedded database. +You can customize the schema storage by using the Spring Boot SQL database and JDBC configuration options.

The following example shows a Spring Boot application that enables the schema registry:

@SpringBootApplication
+@EnableSchemaRegistryServer
+public class SchemaRegistryServerApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(SchemaRegistryServerApplication.class, args);
+    }
+}

30.5.1 Schema Registry Server API

The Schema Registry Server API consists of the following operations:

Registering a New Schema

To register a new schema, send a POST request to the / endpoint.

The / accepts a JSON payload with the following fields:

  • subject: The schema subject
  • format: The schema format
  • definition: The schema definition

Its response is a schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Retrieving an Existing Schema by Subject, Format, and Version

To retrieve an existing schema by subject, format, and version, send GET request to the /{subject}/{format}/{version} endpoint.

Its response is a schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Retrieving an Existing Schema by Subject and Format

To retrieve an existing schema by subject and format, send a GET request to the /subject/format endpoint.

Its response is a list of schemas with each schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Retrieving an Existing Schema by ID

To retrieve a schema by its ID, send a GET request to the /schemas/{id} endpoint.

Its response is a schema object in JSON, with the following fields:

  • id: The schema ID
  • subject: The schema subject
  • format: The schema format
  • version: The schema version
  • definition: The schema definition

Deleting a Schema by Subject, Format, and Version

To delete a schema identified by its subject, format, and version, send a DELETE request to the /{subject}/{format}/{version} endpoint.

Deleting a Schema by ID

To delete a schema by its ID, send a DELETE request to the /schemas/{id} endpoint.

Deleting a Schema by Subject

DELETE /{subject}

Delete existing schemas by their subject.

[Note]Note

This note applies to users of Spring Cloud Stream 1.1.0.RELEASE only. +Spring Cloud Stream 1.1.0.RELEASE used the table name, schema, for storing Schema objects. Schema is a keyword in a number of database implementations. +To avoid any conflicts in the future, starting with 1.1.1.RELEASE, we have opted for the name SCHEMA_REPOSITORY for the storage table. +Any Spring Cloud Stream 1.1.0.RELEASE users who upgrade should migrate their existing schemas to the new table before upgrading.

30.5.2 Using Confluent’s Schema Registry

The default configuration creates a DefaultSchemaRegistryClient bean. +If you want to use the Confluent schema registry, you need to create a bean of type ConfluentSchemaRegistryClient, which supersedes the one configured by default by the framework. The following example shows how to create such a bean:

@Bean
+public SchemaRegistryClient schemaRegistryClient(@Value("${spring.cloud.stream.schemaRegistryClient.endpoint}") String endpoint){
+  ConfluentSchemaRegistryClient client = new ConfluentSchemaRegistryClient();
+  client.setEndpoint(endpoint);
+  return client;
+}
[Note]Note

The ConfluentSchemaRegistryClient is tested against Confluent platform version 4.0.0.

30.6 Schema Registration and Resolution

To better understand how Spring Cloud Stream registers and resolves new schemas and its use of Avro schema comparison features, we provide two separate subsections:

30.6.1 Schema Registration Process (Serialization)

The first part of the registration process is extracting a schema from the payload that is being sent over a channel. +Avro types such as SpecificRecord or GenericRecord already contain a schema, which can be retrieved immediately from the instance. +In the case of POJOs, a schema is inferred if the spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled property is set to true (the default).

Figure 30.1. Schema Writer Resolution Process

schema resolution

Ones a schema is obtained, the converter loads its metadata (version) from the remote server. +First, it queries a local cache. If no result is found, it submits the data to the server, which replies with versioning information. +The converter always caches the results to avoid the overhead of querying the Schema Server for every new message that needs to be serialized.

Figure 30.2. Schema Registration Process

registration

With the schema version information, the converter sets the contentType header of the message to carry the version information — for example: application/vnd.user.v1+avro.

30.6.2 Schema Resolution Process (Deserialization)

When reading messages that contain version information (that is, a contentType header with a scheme like the one described under “Section 30.6.1, “Schema Registration Process (Serialization)””), the converter queries the Schema server to fetch the writer schema of the message. +Once it has found the correct schema of the incoming message, it retrieves the reader schema and, by using Avro’s schema resolution support, reads it into the reader definition (setting defaults and any missing properties).

Figure 30.3. Schema Reading Resolution Process

schema reading

[Note]Note

You should understand the difference between a writer schema (the application that wrote the message) and a reader schema (the receiving application). +We suggest taking a moment to read the Avro terminology and understand the process. +Spring Cloud Stream always fetches the writer schema to determine how to read a message. +If you want to get Avro’s schema evolution support working, you need to make sure that a readerSchema was properly set for your application.

31. Inter-Application Communication

31.1 Connecting Multiple Application Instances

While Spring Cloud Stream makes it easy for individual Spring Boot applications to connect to messaging systems, the typical scenario for Spring Cloud Stream is the creation of multi-application pipelines, where microservice applications send data to each other. +You can achieve this scenario by correlating the input and output destinations of adjacent applications.

Supposing that a design calls for the Time Source application to send data to the Log Sink application, you can use a common destination named ticktock for bindings within both applications.

Time Source (that has the channel name output) will set the following property:

spring.cloud.stream.bindings.output.destination=ticktock

Log Sink (that has the channel name input) will set the following property:

spring.cloud.stream.bindings.input.destination=ticktock

31.2 Instance Index and Instance Count

When scaling up Spring Cloud Stream applications, each instance can receive information about how many other instances of the same application exist and what its own instance index is. +Spring Cloud Stream does this through the spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex properties. +For example, if there are three instances of a HDFS sink application, all three instances will have spring.cloud.stream.instanceCount set to 3, and the individual applications will have spring.cloud.stream.instanceIndex set to 0, 1, and 2, respectively.

When Spring Cloud Stream applications are deployed via Spring Cloud Data Flow, these properties are configured automatically; when Spring Cloud Stream applications are launched independently, these properties must be set correctly. +By default, spring.cloud.stream.instanceCount is 1, and spring.cloud.stream.instanceIndex is 0.

In a scaled-up scenario, correct configuration of these two properties is important for addressing partitioning behavior (see below) in general, and the two properties are always required by certain binders (e.g., the Kafka binder) in order to ensure that data are split correctly across multiple consumer instances.

31.3 Partitioning

31.3.1 Configuring Output Bindings for Partitioning

An output binding is configured to send partitioned data by setting one and only one of its partitionKeyExpression or partitionKeyExtractorClass properties, as well as its partitionCount property. +For example, the following is a valid and typical configuration:

spring.cloud.stream.bindings.output.producer.partitionKeyExpression=payload.id
+spring.cloud.stream.bindings.output.producer.partitionCount=5

Based on the above example configuration, data will be sent to the target partition using the following logic.

A partition key’s value is calculated for each message sent to a partitioned output channel based on the partitionKeyExpression. +The partitionKeyExpression is a SpEL expression which is evaluated against the outbound message for extracting the partitioning key.

If a SpEL expression is not sufficient for your needs, you can instead calculate the partition key value by setting the property partitionKeyExtractorClass to a class which implements the org.springframework.cloud.stream.binder.PartitionKeyExtractorStrategy interface. +While the SpEL expression should usually suffice, more complex cases may use the custom implementation strategy. +In that case, the property 'partitionKeyExtractorClass' can be set as follows:

spring.cloud.stream.bindings.output.producer.partitionKeyExtractorClass=com.example.MyKeyExtractor
+spring.cloud.stream.bindings.output.producer.partitionCount=5

Once the message key is calculated, the partition selection process will determine the target partition as a value between 0 and partitionCount - 1. +The default calculation, applicable in most scenarios, is based on the formula key.hashCode() % partitionCount. +This can be customized on the binding, either by setting a SpEL expression to be evaluated against the 'key' (via the partitionSelectorExpression property) or by setting a org.springframework.cloud.stream.binder.PartitionSelectorStrategy implementation (via the partitionSelectorClass property).

The binding level properties for 'partitionSelectorExpression' and 'partitionSelectorClass' can be specified similar to the way 'partitionKeyExpression' and 'partitionKeyExtractorClass' properties are specified in the above examples. +Additional properties can be configured for more advanced scenarios, as described in the following section.

Spring-managed custom PartitionKeyExtractorClass implementations

In the example above, a custom strategy such as MyKeyExtractor is instantiated by the Spring Cloud Stream directly. +In some cases, it is necessary for such a custom strategy implementation to be created as a Spring bean, for being able to be managed by Spring, so that it can perform dependency injection, property binding, etc. +This can be done by configuring it as a @Bean in the application context and using the fully qualified class name as the bean’s name, as in the following example.

@Bean(name="com.example.MyKeyExtractor")
+public MyKeyExtractor extractor() {
+    return new MyKeyExtractor();
+}

As a Spring bean, the custom strategy benefits from the full lifecycle of a Spring bean. +For example, if the implementation need access to the application context directly, it can make implement 'ApplicationContextAware'.

Configuring Input Bindings for Partitioning

An input binding (with the channel name input) is configured to receive partitioned data by setting its partitioned property, as well as the instanceIndex and instanceCount properties on the application itself, as in the following example:

spring.cloud.stream.bindings.input.consumer.partitioned=true
+spring.cloud.stream.instanceIndex=3
+spring.cloud.stream.instanceCount=5

The instanceCount value represents the total number of application instances between which the data need to be partitioned, and the instanceIndex must be a unique value across the multiple instances, between 0 and instanceCount - 1. +The instance index helps each application instance to identify the unique partition (or, in the case of Kafka, the partition set) from which it receives data. +It is important to set both values correctly in order to ensure that all of the data is consumed and that the application instances receive mutually exclusive datasets.

While a scenario which using multiple instances for partitioned data processing may be complex to set up in a standalone case, Spring Cloud Dataflow can simplify the process significantly by populating both the input and output values correctly as well as relying on the runtime infrastructure to provide information about the instance index and instance count.

32. Testing

Spring Cloud Stream provides support for testing your microservice applications without connecting to a messaging system. +You can do that by using the TestSupportBinder provided by the spring-cloud-stream-test-support library, which can be added as a test dependency to the application:

   <dependency>
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-stream-test-support</artifactId>
+       <scope>test</scope>
+   </dependency>
[Note]Note

The TestSupportBinder uses the Spring Boot autoconfiguration mechanism to supersede the other binders found on the classpath. +Therefore, when adding a binder as a dependency, make sure that the test scope is being used.

The TestSupportBinder allows users to interact with the bound channels and inspect what messages are sent and received by the application

For outbound message channels, the TestSupportBinder registers a single subscriber and retains the messages emitted by the application in a MessageCollector. +They can be retrieved during tests and have assertions made against them.

The user can also send messages to inbound message channels, so that the consumer application can consume the messages. +The following example shows how to test both input and output channels on a processor.

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment= SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class ExampleTest {
+
+  @Autowired
+  private Processor processor;
+
+  @Autowired
+  private MessageCollector messageCollector;
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void testWiring() {
+    Message<String> message = new GenericMessage<>("hello");
+    processor.input().send(message);
+    Message<String> received = (Message<String>) messageCollector.forChannel(processor.output()).poll();
+    assertThat(received.getPayload(), equalTo("hello world"));
+  }
+
+
+  @SpringBootApplication
+  @EnableBinding(Processor.class)
+  public static class MyProcessor {
+
+    @Autowired
+    private Processor channels;
+
+    @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
+    public String transform(String in) {
+      return in + " world";
+    }
+  }
+}

In the example above, we are creating an application that has an input and an output channel, bound through the Processor interface. +The bound interface is injected into the test so we can have access to both channels. +We are sending a message on the input channel and we are using the MessageCollector provided by Spring Cloud Stream’s test support to capture the message has been sent to the output channel as a result. +Once we have received the message, we can validate that the component functions correctly.

32.1 Disabling the test binder autoconfiguration

The intent behind the test binder superseding all the other binders on the classpath is to make it easy to test your applications without making changes to your production dependencies. +In some cases (e.g. integration tests) it is useful to use the actual production binders instead, and that requires disabling the test binder autoconfiguration. +In order to do so, you can exclude the org.springframework.cloud.stream.test.binder.TestSupportBinderAutoConfiguration class using one of the Spring Boot autoconfiguration exclusion mechanisms, as in the following example.

	@SpringBootApplication(exclude = TestSupportBinderAutoConfiguration.class)
+	@EnableBinding(Processor.class)
+	public static class MyProcessor {
+
+		@Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
+		public String transform(String in) {
+			return in + " world";
+		}
+	}

When autoconfiguration is disabled, the test binder is available on the classpath, and its defaultCandidate property is set to false, so that it does not interfere with the regular user configuration. It can be referenced under the name test e.g.:

spring.cloud.stream.defaultBinder=test

33. Health Indicator

Spring Cloud Stream provides a health indicator for binders. +It is registered under the name binders and can be enabled or disabled by setting the management.health.binders.enabled property.

By default management.health.binders.enabled is set to false. +Setting management.health.binders.enabled to true enables the health indicator, allowing you to access the /health endpoint to retrieve the binder health indicators.

Health indicators are binder-specific and certain binder implementations may not necessarily provide a health indicator.

34. Metrics Emitter

Spring Cloud Stream provides a module called spring-cloud-stream-metrics that can be used to emit any available metric from Spring Boot metrics endpoint to a named channel. +This module allow operators to collect metrics from stream applications without relying on polling their endpoints.

The module is activated when you set the destination name for metrics binding, e.g. spring.cloud.stream.bindings.applicationMetrics.destination=<DESTINATION_NAME>. +applicationMetrics can be configured in a similar fashion to any other producer binding. +The default contentType setting of applicationMetrics is application/json.

The following properties can be used for customizing the emission of metrics:

spring.cloud.stream.metrics.key
The name of the metric being emitted. Should be an unique value per application.
Default
${spring.application.name:${vcap.application.name:${spring.config.name:application}}}
spring.cloud.stream.metrics.prefix

Prefix string to be prepended to the metrics key.

Default: ``

spring.cloud.stream.metrics.properties

Just like the includes option, it allows white listing application properties that will be added to the metrics payload

Default: null.

A detailed overview of the metrics export process can be found in the Spring Boot reference documentation. +Spring Cloud Stream provides a metric exporter named application that can be configured via regular Spring Boot metrics configuration properties.

The exporter can be configured either by using the global Spring Boot configuration settings for exporters, or by using exporter-specific properties. +For using the global configuration settings, the properties should be prefixed by spring.metric.export (e.g. spring.metric.export.includes=integration**). +These configuration options will apply to all exporters (unless they have been configured differently). +Alternatively, if it is intended to use configuration settings that are different from the other exporters (e.g. for restricting the number of metrics published), the Spring Cloud Stream provided metrics exporter can be configured using the prefix spring.metrics.export.triggers.application (e.g. spring.metrics.export.triggers.application.includes=integration**).

[Note]Note

Due to Spring Boot’s relaxed binding the value of a property being included can be slightly different than the original value.

As a rule of thumb, the metric exporter will attempt to normalize all the properties in a consistent format using the dot notation (e.g. JAVA_HOME becomes java.home).

The goal of normalization is to make downstream consumers of those metrics capable of receiving property names consistently, regardless of how they are set on the monitored application (--spring.application.name or SPRING_APPLICATION_NAME would always yield spring.application.name).

Below is a sample of the data published to the channel in JSON format by the following command:

java -jar time-source.jar \
+    --spring.cloud.stream.bindings.applicationMetrics.destination=someMetrics \
+    --spring.cloud.stream.metrics.properties=spring.application** \
+    --spring.metrics.export.includes=integration.channel.input**,integration.channel.output**

The resulting JSON is:

{
+   "name":"time-source",
+   "metrics":[
+      {
+         "name":"integration.channel.output.errorRate.mean",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.max",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.min",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.stdev",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.errorRate.count",
+         "value":0.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendCount",
+         "value":6.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.mean",
+         "value":0.994885872292989,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.max",
+         "value":1.006247080013156,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.min",
+         "value":1.0012035220116378,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.stdev",
+         "value":6.505181111084848E-4,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      },
+      {
+         "name":"integration.channel.output.sendRate.count",
+         "value":6.0,
+         "timestamp":"2017-04-11T16:56:35.790Z"
+      }
+   ],
+   "createdTime":"2017-04-11T20:56:35.790Z",
+   "properties":{
+      "spring.application.name":"time-source",
+      "spring.application.index":"0"
+   }
+}

35. Samples

For Spring Cloud Stream samples, please refer to the spring-cloud-stream-samples repository on GitHub.

36. Getting Started

To get started with creating Spring Cloud Stream applications, visit the Spring Initializr and create a new Maven project named "GreetingSource". +Select Spring Boot {supported-spring-boot-version} in the dropdown. +In the Search for dependencies text box type Stream Rabbit or Stream Kafka depending on what binder you want to use.

Next, create a new class, GreetingSource, in the same package as the GreetingSourceApplication class. +Give it the following code:

import org.springframework.cloud.stream.annotation.EnableBinding;
+import org.springframework.cloud.stream.messaging.Source;
+import org.springframework.integration.annotation.InboundChannelAdapter;
+
+@EnableBinding(Source.class)
+public class GreetingSource {
+
+    @InboundChannelAdapter(Source.OUTPUT)
+    public String greet() {
+        return "hello world " + System.currentTimeMillis();
+    }
+}

The @EnableBinding annotation is what triggers the creation of Spring Integration infrastructure components. +Specifically, it will create a Kafka connection factory, a Kafka outbound channel adapter, and the message channel defined inside the Source interface:

public interface Source {
+
+  String OUTPUT = "output";
+
+  @Output(Source.OUTPUT)
+  MessageChannel output();
+
+}

The auto-configuration also creates a default poller, so that the greet() method will be invoked once per second. +The standard Spring Integration @InboundChannelAdapter annotation sends a message to the source’s output channel, using the return value as the payload of the message.

To test-drive this setup, run a Kafka message broker. +An easy way to do this is to use a Docker image:

# On OS X
+$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=`docker-machine ip \`docker-machine active\`` --env ADVERTISED_PORT=9092 spotify/kafka
+
+# On Linux
+$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=localhost --env ADVERTISED_PORT=9092 spotify/kafka

Build the application:

./mvnw clean package

The consumer application is coded in a similar manner. +Go back to Initializr and create another project, named LoggingSink. +Then create a new class, LoggingSink, in the same package as the class LoggingSinkApplication and with the following code:

import org.springframework.cloud.stream.annotation.EnableBinding;
+import org.springframework.cloud.stream.annotation.StreamListener;
+import org.springframework.cloud.stream.messaging.Sink;
+
+@EnableBinding(Sink.class)
+public class LoggingSink {
+
+    @StreamListener(Sink.INPUT)
+    public void log(String message) {
+        System.out.println(message);
+    }
+}

Build the application:

./mvnw clean package

To connect the GreetingSource application to the LoggingSink application, each application must share the same destination name. +Starting up both applications as shown below, you will see the consumer application printing "hello world" and a timestamp to the console:

cd GreetingSource
+java -jar target/GreetingSource-0.0.1-SNAPSHOT.jar --spring.cloud.stream.bindings.output.destination=mydest
+
+cd LoggingSink
+java -jar target/LoggingSink-0.0.1-SNAPSHOT.jar --server.port=8090 --spring.cloud.stream.bindings.input.destination=mydest

(The different server port prevents collisions of the HTTP port used to service the Spring Boot Actuator endpoints in the two applications.)

The output of the LoggingSink application will look something like the following:

[           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8090 (http)
+[           main] com.example.LoggingSinkApplication       : Started LoggingSinkApplication in 6.828 seconds (JVM running for 7.371)
+hello world 1458595076731
+hello world 1458595077732
+hello world 1458595078733
+hello world 1458595079734
+hello world 1458595080735

36.1 Deploying Stream applications on CloudFoundry

On CloudFoundry services are usually exposed via a special environment variable called VCAP_SERVICES.

When configuring your binder connections, you can use the values from an environment variable as explained on the dataflow cloudfoundry server docs.

Part V. Binder Implementations

37. Apache Kafka Binder

37.1 Usage

For using the Apache Kafka binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-kafka</artifactId>
+</dependency>

Alternatively, you can also use the Spring Cloud Stream Kafka Starter.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-starter-stream-kafka</artifactId>
+</dependency>

37.2 Apache Kafka Binder Overview

A simplified diagram of how the Apache Kafka binder operates can be seen below.

Figure 37.1. Kafka Binder

kafka binder

The Apache Kafka Binder implementation maps each destination to an Apache Kafka topic. +The consumer group maps directly to the same Apache Kafka concept. +Partitioning also maps directly to Apache Kafka partitions as well.

37.3 Configuration Options

This section contains the configuration options used by the Apache Kafka binder.

For common configuration options and properties pertaining to binder, refer to the core documentation.

37.3.1 Kafka Binder Properties

spring.cloud.stream.kafka.binder.brokers

A list of brokers to which the Kafka binder will connect.

Default: localhost.

spring.cloud.stream.kafka.binder.defaultBrokerPort

brokers allows hosts specified with or without port information (e.g., host1,host2:port2). +This sets the default port when no port is configured in the broker list.

Default: 9092.

spring.cloud.stream.kafka.binder.zkNodes

A list of ZooKeeper nodes to which the Kafka binder can connect.

Default: localhost.

spring.cloud.stream.kafka.binder.defaultZkPort

zkNodes allows hosts specified with or without port information (e.g., host1,host2:port2). +This sets the default port when no port is configured in the node list.

Default: 2181.

spring.cloud.stream.kafka.binder.configuration

Key/Value map of client properties (both producers and consumer) passed to all clients created by the binder. +Due to the fact that these properties will be used by both producers and consumers, usage should be restricted to common properties, especially security settings.

Default: Empty map.

spring.cloud.stream.kafka.binder.headers

The list of custom headers that will be transported by the binder.

Default: empty.

spring.cloud.stream.kafka.binder.healthTimeout

The time to wait to get partition information in seconds; default 60. +Health will report as down if this timer expires.

Default: 10.

spring.cloud.stream.kafka.binder.offsetUpdateTimeWindow

The frequency, in milliseconds, with which offsets are saved. +Ignored if 0.

Default: 10000.

spring.cloud.stream.kafka.binder.offsetUpdateCount

The frequency, in number of updates, which which consumed offsets are persisted. +Ignored if 0. +Mutually exclusive with offsetUpdateTimeWindow.

Default: 0.

spring.cloud.stream.kafka.binder.requiredAcks

The number of required acks on the broker.

Default: 1.

spring.cloud.stream.kafka.binder.minPartitionCount

Effective only if autoCreateTopics or autoAddPartitions is set. +The global minimum number of partitions that the binder will configure on topics on which it produces/consumes data. +It can be superseded by the partitionCount setting of the producer or by the value of instanceCount * concurrency settings of the producer (if either is larger).

Default: 1.

spring.cloud.stream.kafka.binder.replicationFactor

The replication factor of auto-created topics if autoCreateTopics is active.

Default: 1.

spring.cloud.stream.kafka.binder.autoCreateTopics

If set to true, the binder will create new topics automatically. +If set to false, the binder will rely on the topics being already configured. +In the latter case, if the topics do not exist, the binder will fail to start. +Of note, this setting is independent of the auto.topic.create.enable setting of the broker and it does not influence it: if the server is set to auto-create topics, they may be created as part of the metadata retrieval request, with default broker settings.

Default: true.

spring.cloud.stream.kafka.binder.autoAddPartitions

If set to true, the binder will create add new partitions if required. +If set to false, the binder will rely on the partition size of the topic being already configured. +If the partition count of the target topic is smaller than the expected value, the binder will fail to start.

Default: false.

spring.cloud.stream.kafka.binder.socketBufferSize

Size (in bytes) of the socket buffer to be used by the Kafka consumers.

Default: 2097152.

37.3.2 Kafka Consumer Properties

The following properties are available for Kafka consumers only and +must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.consumer..

autoRebalanceEnabled

When true, topic partitions will be automatically rebalanced between the members of a consumer group. +When false, each consumer will be assigned a fixed set of partitions based on spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex. +This requires both spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex properties to be set appropriately on each launched instance. +The property spring.cloud.stream.instanceCount must typically be greater than 1 in this case.

Default: true.

autoCommitOffset

Whether to autocommit offsets when a message has been processed. +If set to false, a header with the key kafka_acknowledgment of the type org.springframework.kafka.support.Acknowledgment header will be present in the inbound message. +Applications may use this header for acknowledging messages. +See the examples section for details. +When this property is set to false, Kafka binder will set the ack mode to org.springframework.kafka.listener.AbstractMessageListenerContainer.AckMode.MANUAL.

Default: true.

autoCommitOnError

Effective only if autoCommitOffset is set to true. +If set to false it suppresses auto-commits for messages that result in errors, and will commit only for successful messages, allows a stream to automatically replay from the last successfully processed message, in case of persistent failures. +If set to true, it will always auto-commit (if auto-commit is enabled). +If not set (default), it effectively has the same value as enableDlq, auto-committing erroneous messages if they are sent to a DLQ, and not committing them otherwise.

Default: not set.

recoveryInterval

The interval between connection recovery attempts, in milliseconds.

Default: 5000.

startOffset

The starting offset for new groups. +Allowed values: earliest, latest. +If the consumer group is set explicitly for the consumer 'binding' (via spring.cloud.stream.bindings.<channelName>.group), then 'startOffset' is set to earliest; otherwise it is set to latest for the anonymous consumer group.

Default: null (equivalent to earliest).

enableDlq

When set to true, it will send enable DLQ behavior for the consumer. +By default, messages that result in errors will be forwarded to a topic named error.<destination>.<group>. +The DLQ topic name can be configurable via the property dlqName. +This provides an alternative option to the more common Kafka replay scenario for the case when the number of errors is relatively small and replaying the entire original topic may be too cumbersome.

Default: false.

configuration

Map with a key/value pair containing generic Kafka consumer properties.

Default: Empty map.

dlqName

The name of the DLQ topic to receive the error messages.

Default: null (If not specified, messages that result in errors will be forwarded to a topic named error.<destination>.<group>).

37.3.3 Kafka Producer Properties

The following properties are available for Kafka producers only and +must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.producer..

bufferSize

Upper limit, in bytes, of how much data the Kafka producer will attempt to batch before sending.

Default: 16384.

sync

Whether the producer is synchronous.

Default: false.

batchTimeout

How long the producer will wait before sending in order to allow more messages to accumulate in the same batch. +(Normally the producer does not wait at all, and simply sends all the messages that accumulated while the previous send was in progress.) A non-zero value may increase throughput at the expense of latency.

Default: 0.

messageKeyExpression

A SpEL expression evaluated against the outgoing message used to populate the key of the produced Kafka message. +For example headers.key or payload.myKey.

Default: none.

configuration

Map with a key/value pair containing generic Kafka producer properties.

Default: Empty map.

[Note]Note

The Kafka binder will use the partitionCount setting of the producer as a hint to create a topic with the given partition count (in conjunction with the minPartitionCount, the maximum of the two being the value being used). +Exercise caution when configuring both minPartitionCount for a binder and partitionCount for an application, as the larger value will be used. +If a topic already exists with a smaller partition count and autoAddPartitions is disabled (the default), then the binder will fail to start. +If a topic already exists with a smaller partition count and autoAddPartitions is enabled, new partitions will be added. +If a topic already exists with a larger number of partitions than the maximum of (minPartitionCount and partitionCount), the existing partition count will be used.

37.3.4 Usage examples

In this section, we illustrate the use of the above properties for specific scenarios.

Example: Setting autoCommitOffset false and relying on manual acking.

This example illustrates how one may manually acknowledge offsets in a consumer application.

This example requires that spring.cloud.stream.kafka.bindings.input.consumer.autoCommitOffset is set to false. +Use the corresponding input channel name for your example.

@SpringBootApplication
+@EnableBinding(Sink.class)
+public class ManuallyAcknowdledgingConsumer {
+
+ public static void main(String[] args) {
+     SpringApplication.run(ManuallyAcknowdledgingConsumer.class, args);
+ }
+
+ @StreamListener(Sink.INPUT)
+ public void process(Message<?> message) {
+     Acknowledgment acknowledgment = message.getHeaders().get(KafkaHeaders.ACKNOWLEDGMENT, Acknowledgment.class);
+     if (acknowledgment != null) {
+         System.out.println("Acknowledgment provided");
+         acknowledgment.acknowledge();
+     }
+ }
+}

Example: security configuration

Apache Kafka 0.9 supports secure connections between client and brokers. +To take advantage of this feature, follow the guidelines in the Apache Kafka Documentation as well as the Kafka 0.9 security guidelines from the Confluent documentation. +Use the spring.cloud.stream.kafka.binder.configuration option to set security properties for all clients created by the binder.

For example, for setting security.protocol to SASL_SSL, set:

spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_SSL

All the other security properties can be set in a similar manner.

When using Kerberos, follow the instructions in the reference documentation for creating and referencing the JAAS configuration.

Spring Cloud Stream supports passing JAAS configuration information to the application using a JAAS configuration file and using Spring Boot properties.

Using JAAS configuration files

The JAAS, and (optionally) krb5 file locations can be set for Spring Cloud Stream applications by using system properties. +Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using a JAAS configuration file:

 java -Djava.security.auth.login.config=/path.to/kafka_client_jaas.conf -jar log.jar \
+   --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \
+   --spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \
+   --spring.cloud.stream.bindings.input.destination=stream.ticktock \
+   --spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT
Using Spring Boot properties

As an alternative to having a JAAS configuration file, Spring Cloud Stream provides a mechanism for setting up the JAAS configuration for Spring Cloud Stream applications using Spring Boot properties.

The following properties can be used for configuring the login context of the Kafka client.

spring.cloud.stream.kafka.binder.jaas.loginModule

The login module name. Not necessary to be set in normal cases.

Default: com.sun.security.auth.module.Krb5LoginModule.

spring.cloud.stream.kafka.binder.jaas.controlFlag

The control flag of the login module.

Default: required.

spring.cloud.stream.kafka.binder.jaas.options

Map with a key/value pair containing the login module options.

Default: Empty map.

Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using Spring Boot configuration properties:

 java --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \
+   --spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \
+   --spring.cloud.stream.bindings.input.destination=stream.ticktock \
+   --spring.cloud.stream.kafka.binder.autoCreateTopics=false \
+   --spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT \
+   --spring.cloud.stream.kafka.binder.jaas.options.useKeyTab=true \
+   --spring.cloud.stream.kafka.binder.jaas.options.storeKey=true \
+   --spring.cloud.stream.kafka.binder.jaas.options.keyTab=/etc/security/keytabs/kafka_client.keytab \
+   --spring.cloud.stream.kafka.binder.jaas.options.principal=kafka-client-1@EXAMPLE.COM

This represents the equivalent of the following JAAS file:

KafkaClient {
+    com.sun.security.auth.module.Krb5LoginModule required
+    useKeyTab=true
+    storeKey=true
+    keyTab="/etc/security/keytabs/kafka_client.keytab"
+    principal="kafka-client-1@EXAMPLE.COM";
+};

If the topics required already exist on the broker, or will be created by an administrator, autocreation can be turned off and only client JAAS properties need to be sent. As an alternative to setting spring.cloud.stream.kafka.binder.autoCreateTopics you can simply remove the broker dependency from the application. See the section called “Excluding Kafka broker jar from the classpath of the binder based application” for details.

[Note]Note

Do not mix JAAS configuration files and Spring Boot properties in the same application. +If the -Djava.security.auth.login.config system property is already present, Spring Cloud Stream will ignore the Spring Boot properties.

[Note]Note

Exercise caution when using the autoCreateTopics and autoAddPartitions if using Kerberos. +Usually applications may use principals that do not have administrative rights in Kafka and Zookeeper, and relying on Spring Cloud Stream to create/modify topics may fail. +In secure environments, we strongly recommend creating topics and managing ACLs administratively using Kafka tooling.

Using the binder with Apache Kafka 0.10

The default Kafka support in Spring Cloud Stream Kafka binder is for Kafka version 0.10.1.1. The binder also supports connecting to other 0.10 based versions and 0.9 clients. +In order to do this, when you create the project that contains your application, include spring-cloud-starter-stream-kafka as you normally would do for the default binder. +Then add these dependencies at the top of the <dependencies> section in the pom.xml file to override the dependencies.

Here is an example for downgrading your application to 0.10.0.1. Since it is still on the 0.10 line, the default spring-kafka and spring-integration-kafka versions can be retained.

<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka_2.11</artifactId>
+  <version>0.10.0.1</version>
+  <exclusions>
+    <exclusion>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-log4j12</artifactId>
+    </exclusion>
+  </exclusions>
+</dependency>
+<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka-clients</artifactId>
+  <version>0.10.0.1</version>
+</dependency>

Here is another example of using 0.9.0.1 version.

<dependency>
+  <groupId>org.springframework.kafka</groupId>
+  <artifactId>spring-kafka</artifactId>
+  <version>1.0.5.RELEASE</version>
+</dependency>
+<dependency>
+  <groupId>org.springframework.integration</groupId>
+  <artifactId>spring-integration-kafka</artifactId>
+  <version>2.0.1.RELEASE</version>
+</dependency>
+<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka_2.11</artifactId>
+  <version>0.9.0.1</version>
+  <exclusions>
+    <exclusion>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-log4j12</artifactId>
+    </exclusion>
+  </exclusions>
+</dependency>
+<dependency>
+  <groupId>org.apache.kafka</groupId>
+  <artifactId>kafka-clients</artifactId>
+  <version>0.9.0.1</version>
+</dependency>
[Note]Note

The versions above are provided only for the sake of the example. +For best results, we recommend using the most recent 0.10-compatible versions of the projects.

Excluding Kafka broker jar from the classpath of the binder based application

The Apache Kafka Binder uses the administrative utilities which are part of the Apache Kafka server library to create and reconfigure topics. +If the inclusion of the Apache Kafka server library and its dependencies is not necessary at runtime because the application will rely on the topics being configured administratively, the Kafka binder allows for Apache Kafka server dependency to be excluded from the application.

If you use non default versions for Kafka dependencies as advised above, all you have to do is not to include the kafka broker dependency. +If you use the default Kafka version, then ensure that you exclude the kafka broker jar from the spring-cloud-starter-stream-kafka dependency as following.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-starter-stream-kafka</artifactId>
+  <exclusions>
+    <exclusion>
+      <groupId>org.apache.kafka</groupId>
+      <artifactId>kafka_2.11</artifactId>
+    </exclusion>
+  </exclusions>
+</dependency>

If you exclude the Apache Kafka server dependency and the topic is not present on the server, then the Apache Kafka broker will create the topic if auto topic creation is enabled on the server. +Please keep in mind that if you are relying on this, then the Kafka server will use the default number of partitions and replication factors. +On the other hand, if auto topic creation is disabled on the server, then care must be taken before running the application to create the topic with the desired number of partitions.

If you want to have full control over how partitions are allocated, then leave the default settings as they are, i.e. do not exclude the kafka broker jar and ensure that spring.cloud.stream.kafka.binder.autoCreateTopics is set to true, which is the default.

37.4 Kafka Streams Binding Capabilities of Spring Cloud Stream

Spring Cloud Stream Kafka support also includes a binder specifically designed for Kafka Streams binding. +Using this binder, applications can be written that leverage the Kafka Streams API. +For more information on Kafka Streams, see Kafka Streams API Developer Manual

Kafka Streams support in Spring Cloud Stream is based on the foundations provided by the Spring Kafka project. For details on that support, see Kafaka Streams Support in Spring Kafka.

Here are the maven coordinates for the Spring Cloud Stream KStream binder artifact.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-kstream</artifactId>
+</dependency>

In addition to leveraging the Spring Cloud Stream programming model which is based on Spring Boot, one of the main other benefits that the KStream binder provides is the fact that it avoids the boilerplate configuration that one needs to write when using the Kafka Streams API directly. +High level streams DSL provided through the Kafka Streams API can be used through Spring Cloud Stream in the current support.

37.4.1 Usage example of high level streams DSL

This application will listen from a Kafka topic and write the word count for each unique word that it sees in a 5 seconds time window.

@SpringBootApplication
+@EnableBinding(KStreamProcessor.class)
+public class WordCountProcessorApplication {
+
+	@StreamListener("input")
+	@SendTo("output")
+	public KStream<?, String> process(KStream<?, String> input) {
+		return input
+				.flatMapValues(value -> Arrays.asList(value.toLowerCase().split("\\W+")))
+				.map((key, word) -> new KeyValue<>(word, word))
+				.groupByKey(Serdes.String(), Serdes.String())
+				.count(TimeWindows.of(5000), "store-name")
+				.toStream()
+				.map((w, c) -> new KeyValue<>(null, "Count for " + w.key() + ": " + c));
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(WordCountProcessorApplication.class, args);
+	}

If you build it as Spring Boot runnable fat jar, you can run the above example in the following way:

java -jar uber.jar  --spring.cloud.stream.bindings.input.destination=words --spring.cloud.stream.bindings.output.destination=counts

This means that the application will listen from the incoming Kafka topic words and write to the output topic counts.

Spring Cloud Stream will ensure that the messages from both the incoming and outgoing topics are bound as KStream objects. +As one may observe, the developer can exclusively focus on the business aspects of the code, i.e. writing the logic required in the processor rather than setting up the streams specific configuration required by the Kafka Streams infrastructure. +All those boilerplate is handled by Spring Cloud Stream behind the scenes.

37.4.2 Support for interactive queries

If access to the KafkaStreams is needed for interactive queries, the internal KafkaStreams instance can be accessed via KStreamBuilderFactoryBean.getKafkaStreams(). +You can autowire the KStreamBuilderFactoryBean instance provided by the KStream binder. Then you can get KafkaStreams instance from it and retrieve the underlying store, execute queries on it, etc.

37.4.3 Kafka Streams properties

configuration

Map with a key/value pair containing properties pertaining to Kafka Streams API. +This property must be prefixed with spring.cloud.stream.kstream.binder..

Following are some examples of using this property.
spring.cloud.stream.kstream.binder.configuration.key.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
+spring.cloud.stream.kstream.binder.configuration.value.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
+spring.cloud.stream.kstream.binder.configuration.commit.interval.ms=1000
For more information about all the properties that may go into streams configuration, see StreamsConfig JavaDocs.

There can also be binding specific properties.

For instance, you can use a different Serde for your input or output destination.

spring.cloud.stream.kstream.bindings.output.producer.keySerde=org.apache.kafka.common.serialization.Serdes$IntegerSerde
+spring.cloud.stream.kstream.bindings.output.producer.valueSerde=org.apache.kafka.common.serialization.Serdes$LongSerde
timewindow.length

Many streaming applications written using Kafka Streams involve windowning operations. +If you specify this property, there is a org.apache.kafka.streams.kstream.TimeWindows bean automatically provided that can be autowired in applications. +This property must be prefixed with spring.cloud.stream.kstream.. +A bean of type org.apache.kafka.streams.kstream.TimeWindows is created only if this property is provided.

Following is an example of using this property.
+Values are provided in milliseconds.
spring.cloud.stream.kstream.timeWindow.length=5000
timewindow.advanceBy

This property goes hand in hand with timewindow.length and has no effect on its own. +If you provide this property, the generated org.apache.kafka.streams.kstream.TimeWindows bean will automatically conatin this information. +This property must be prefixed with spring.cloud.stream.kstream..

Following is an example of using this property.
+Values are provided in milliseconds.
spring.cloud.stream.kstream.timeWindow.advanceBy=1000

37.5 Error Channels

Starting with version 1.3, the binder unconditionally sends exceptions to an error channel for each consumer destination, and can be configured to send async producer send failures to an error channel too. +See the section called “Message Channel Binders and Error Channels” for more information.

The payload of the ErrorMessage for a send failure is a KafkaSendFailureException with properties:

  • failedMessage - the spring-messaging Message<?> that failed to be sent.
  • record - the raw ProducerRecord that was created from the failedMessage

There is no automatic handling of these exceptions (such as sending to a Dead-Letter queue); you can consume these exceptions with your own Spring Integration flow.

37.6 Kafka Metrics

Kafka binder module exposes the following metrics:

spring.cloud.stream.binder.kafka.someGroup.someTopic.lag - this metric indicates how many messages have not been yet consumed from given binder’s topic by given consumer group. +For example if the value of the metric spring.cloud.stream.binder.kafka.myGroup.myTopic.lag is 1000, then consumer group myGroup has 1000 messages to waiting to be consumed from topic myTopic. +This metric is particularly useful to provide auto-scaling feedback to PaaS platform of your choice.

37.7 Dead-Letter Topic Processing

Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them. +If the reason for the dead-lettering is transient, you may wish to route the messages back to the original topic. +However, if the problem is a permanent issue, that could cause an infinite loop. +The following spring-boot application is an example of how to route those messages back to the original topic, but moves them to a third "parking lot" topic after three attempts. +The application is simply another spring-cloud-stream application that reads from the dead-letter topic. +It terminates when no messages are received for 5 seconds.

The examples assume the original destination is so8400out and the consumer group is so8400.

There are several considerations.

  • Consider only running the rerouting when the main application is not running. +Otherwise, the retries for transient errors will be used up very quickly.
  • Alternatively, use a two-stage approach - use this application to route to a third topic, and another to route from there back to the main topic.
  • Since this technique uses a message header to keep track of retries, it won’t work with headerMode=raw. +In that case, consider adding some data to the payload (that can be ignored by the main application).
  • x-retries has to be added to the headers property spring.cloud.stream.kafka.binder.headers=x-retries on both this, and the main application so that the header is transported between the applications.
  • Since kafka is publish/subscribe, replayed messages will be sent to each consumer group, even those that successfully processed a message the first time around.

application.properties.  +

spring.cloud.stream.bindings.input.group=so8400replay
+spring.cloud.stream.bindings.input.destination=error.so8400out.so8400
+
+spring.cloud.stream.bindings.output.destination=so8400out
+spring.cloud.stream.bindings.output.producer.partitioned=true
+
+spring.cloud.stream.bindings.parkingLot.destination=so8400in.parkingLot
+spring.cloud.stream.bindings.parkingLot.producer.partitioned=true
+
+spring.cloud.stream.kafka.binder.configuration.auto.offset.reset=earliest
+
+spring.cloud.stream.kafka.binder.headers=x-retries

+

Application.  +

@SpringBootApplication
+@EnableBinding(TwoOutputProcessor.class)
+public class ReRouteDlqKApplication implements CommandLineRunner {
+
+    private static final String X_RETRIES_HEADER = "x-retries";
+
+    public static void main(String[] args) {
+        SpringApplication.run(ReRouteDlqKApplication.class, args).close();
+    }
+
+    private final AtomicInteger processed = new AtomicInteger();
+
+    @Autowired
+    private MessageChannel parkingLot;
+
+    @StreamListener(Processor.INPUT)
+    @SendTo(Processor.OUTPUT)
+    public Message<?> reRoute(Message<?> failed) {
+        processed.incrementAndGet();
+        Integer retries = failed.getHeaders().get(X_RETRIES_HEADER, Integer.class);
+        if (retries == null) {
+            System.out.println("First retry for " + failed);
+            return MessageBuilder.fromMessage(failed)
+                    .setHeader(X_RETRIES_HEADER, new Integer(1))
+                    .setHeader(BinderHeaders.PARTITION_OVERRIDE,
+                            failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID))
+                    .build();
+        }
+        else if (retries.intValue() < 3) {
+            System.out.println("Another retry for " + failed);
+            return MessageBuilder.fromMessage(failed)
+                    .setHeader(X_RETRIES_HEADER, new Integer(retries.intValue() + 1))
+                    .setHeader(BinderHeaders.PARTITION_OVERRIDE,
+                            failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID))
+                    .build();
+        }
+        else {
+            System.out.println("Retries exhausted for " + failed);
+            parkingLot.send(MessageBuilder.fromMessage(failed)
+                    .setHeader(BinderHeaders.PARTITION_OVERRIDE,
+                            failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID))
+                    .build());
+        }
+        return null;
+    }
+
+    @Override
+    public void run(String... args) throws Exception {
+        while (true) {
+            int count = this.processed.get();
+            Thread.sleep(5000);
+            if (count == this.processed.get()) {
+                System.out.println("Idle, terminating");
+                return;
+            }
+        }
+    }
+
+    public interface TwoOutputProcessor extends Processor {
+
+        @Output("parkingLot")
+        MessageChannel parkingLot();
+
+    }
+
+}

+

38. RabbitMQ Binder

38.1 Usage

For using the RabbitMQ binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-stream-binder-rabbit</artifactId>
+</dependency>

Alternatively, you can also use the Spring Cloud Stream RabbitMQ Starter.

<dependency>
+  <groupId>org.springframework.cloud</groupId>
+  <artifactId>spring-cloud-starter-stream-rabbit</artifactId>
+</dependency>

38.2 RabbitMQ Binder Overview

A simplified diagram of how the RabbitMQ binder operates can be seen below.

Figure 38.1. RabbitMQ Binder

rabbit binder

The RabbitMQ Binder implementation maps each destination to a TopicExchange. +For each consumer group, a Queue will be bound to that TopicExchange. +Each consumer instance have a corresponding RabbitMQ Consumer instance for its group’s Queue. +For partitioned producers/consumers the queues are suffixed with the partition index and use the partition index as routing key.

Using the autoBindDlq option, you can optionally configure the binder to create and configure dead-letter queues (DLQs) (and a dead-letter exchange DLX). +The dead letter queue has the name of the destination, appended with .dlq. +If retry is enabled (maxAttempts > 1) failed messages will be delivered to the DLQ. +If retry is disabled (maxAttempts = 1), you should set requeueRejected to false (default) so that a failed message will be routed to the DLQ, instead of being requeued. +In addition, republishToDlq causes the binder to publish a failed message to the DLQ (instead of rejecting it); this enables additional information to be added to the message in headers, such as the stack trace in the x-exception-stacktrace header. +This option does not need retry enabled; you can republish a failed message after just one attempt. +Starting with version 1.2, you can configure the delivery mode of republished messages; see property republishDeliveryMode.

[Important]Important

Setting requeueRejected to true will cause the message to be requeued and redelivered continually, which is likely not what you want unless the failure issue is transient. +In general, it’s better to enable retry within the binder by setting maxAttempts to greater than one, or set republishToDlq to true.

See Section 38.3.1, “RabbitMQ Binder Properties” for more information about these properties.

The framework does not provide any standard mechanism to consume dead-letter messages (or to re-route them back to the primary queue). +Some options are described in Section 38.6, “Dead-Letter Queue Processing”.

[Note]Note

When multiple RabbitMQ binders are used in a Spring Cloud Stream application, it is important to disable 'RabbitAutoConfiguration' to avoid the same configuration from RabbitAutoConfiguration being applied to the two binders.

Starting with version 1.3, the RabbitMessageChannelBinder creates an internal ConnectionFactory copy for the non-transactional producers to avoid dead locks on consumers when shared, cached connections are blocked because of Memory Alarm on Broker.

38.3 Configuration Options

This section contains settings specific to the RabbitMQ Binder and bound channels.

For general binding configuration options and properties, +please refer to the Spring Cloud Stream core documentation.

38.3.1 RabbitMQ Binder Properties

By default, the RabbitMQ binder uses Spring Boot’s ConnectionFactory, and it therefore supports all Spring Boot configuration options for RabbitMQ. +(For reference, consult the Spring Boot documentation.) +RabbitMQ configuration options use the spring.rabbitmq prefix.

In addition to Spring Boot options, the RabbitMQ binder supports the following properties:

spring.cloud.stream.rabbit.binder.adminAddresses

A comma-separated list of RabbitMQ management plugin URLs. +Only used when nodes contains more than one entry. +Each entry in this list must have a corresponding entry in spring.rabbitmq.addresses. +Only needed if you are using a RabbitMQ cluster and wish to consume from the node that hosts the queue. +See Queue Affinity and the LocalizedQueueConnectionFactory for more information.

Default: empty.

spring.cloud.stream.rabbit.binder.nodes

A comma-separated list of RabbitMQ node names. +When more than one entry, used to locate the server address where a queue is located. +Each entry in this list must have a corresponding entry in spring.rabbitmq.addresses. +Only needed if you are using a RabbitMQ cluster and wish to consume from the node that hosts the queue. +See Queue Affinity and the LocalizedQueueConnectionFactory for more information.

Default: empty.

spring.cloud.stream.rabbit.binder.compressionLevel

Compression level for compressed bindings. +See java.util.zip.Deflater.

Default: 1 (BEST_LEVEL).

38.3.2 RabbitMQ Consumer Properties

The following properties are available for Rabbit consumers only and +must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.consumer..

acknowledgeMode

The acknowledge mode.

Default: AUTO.

autoBindDlq

Whether to automatically declare the DLQ and bind it to the binder DLX.

Default: false.

bindingRoutingKey

The routing key with which to bind the queue to the exchange (if bindQueue is true). +for partitioned destinations -<instanceIndex> will be appended.

Default: #.

bindQueue

Whether to bind the queue to the destination exchange; set to false if you have set up your own infrastructure and have previously created/bound the queue.

Default: true.

deadLetterQueueName

name of the DLQ

Default: prefix+destination.dlq

deadLetterExchange

a DLX to assign to the queue; if autoBindDlq is true

Default: 'prefix+DLX'

deadLetterRoutingKey

a dead letter routing key to assign to the queue; if autoBindDlq is true

Default: destination

declareExchange

Whether to declare the exchange for the destination.

Default: true.

delayedExchange

Whether to declare the exchange as a Delayed Message Exchange - requires the delayed message exchange plugin on the broker. +The x-delayed-type argument is set to the exchangeType.

Default: false.

dlqDeadLetterExchange

if a DLQ is declared, a DLX to assign to that queue

Default: none

dlqDeadLetterRoutingKey

if a DLQ is declared, a dead letter routing key to assign to that queue; default none

Default: none

dlqExpires

how long before an unused dead letter queue is deleted (ms)

Default: no expiration

dlqLazy

Declare the dead letter queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue.

Default: false.

dlqMaxLength

maximum number of messages in the dead letter queue

Default: no limit

dlqMaxLengthBytes

maximum number of total bytes in the dead letter queue from all messages

Default: no limit

dlqMaxPriority

maximum priority of messages in the dead letter queue (0-255)

Default: none

dlqTtl

default time to live to apply to the dead letter queue when declared (ms)

Default: no limit

durableSubscription

Whether subscription should be durable. +Only effective if group is also set.

Default: true.

exchangeAutoDelete

If declareExchange is true, whether the exchange should be auto-delete (removed after the last queue is removed).

Default: true.

exchangeDurable

If declareExchange is true, whether the exchange should be durable (survives broker restart).

Default: true.

exchangeType

The exchange type; direct, fanout or topic for non-partitioned destinations; direct or topic for partitioned destinations.

Default: topic.

exclusive

Create an exclusive consumer; concurrency should be 1 when this is true; often used when strict ordering is required but enabling a hot standby instance to take over after a failure. +See recoveryInterval, which controls how often a standby instance will attempt to consume.

Default: false.

expires

how long before an unused queue is deleted (ms)

Default: no expiration

failedDeclarationRetryInterval

The interval (ms) between attempts to consume from a queue if it is missing.

Default: 5000

headerPatterns

Patterns for headers to be mapped from inbound messages.

Default: ['*'] (all headers).

lazy

Declare the queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue.

Default: false.

maxConcurrency

the maximum number of consumers

Default: 1.

maxLength

maximum number of messages in the queue

Default: no limit

maxLengthBytes

maximum number of total bytes in the queue from all messages

Default: no limit

maxPriority
maximum priority of messages in the queue (0-255)
Default
none
missingQueuesFatal
If the queue cannot be found, treat the condition as fatal and stop the listener container. +Defaults to false so that the container keeps trying to consume from the queue, for example when using a cluster and the node hosting a non HA queue is down.
Default
false
prefetch

Prefetch count.

Default: 1.

prefix

A prefix to be added to the name of the destination and queues.

Default: "".

queueDeclarationRetries
The number of times to retry consuming from a queue if it is missing. +Only relevant if missingQueuesFatal is true; otherwise the container keeps retrying indefinitely.
Default
3
queueNameGroupOnly

When true, consume from a queue with a name equal to the group; otherwise the queue name is destination.group. +This is useful, for example, when using Spring Cloud Stream to consume from an existing RabbitMQ queue.

Default: false.

recoveryInterval

The interval between connection recovery attempts, in milliseconds.

Default: 5000.

requeueRejected

Whether delivery failures should be requeued when retry is disabled or republishToDlq is false.

Default: false.

republishDeliveryMode

When republishToDlq is true, specify the delivery mode of the republished message.

Default: DeliveryMode.PERSISTENT

republishToDlq

By default, messages which fail after retries are exhausted are rejected. +If a dead-letter queue (DLQ) is configured, RabbitMQ will route the failed message (unchanged) to the DLQ. +If set to true, the binder will republish failed messages to the DLQ with additional headers, including the exception message and stack trace from the cause of the final failure.

Default: false

transacted

Whether to use transacted channels.

Default: false.

ttl

default time to live to apply to the queue when declared (ms)

Default: no limit

txSize

The number of deliveries between acks.

Default: 1.

38.3.3 Rabbit Producer Properties

The following properties are available for Rabbit producers only and +must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.producer..

autoBindDlq

Whether to automatically declare the DLQ and bind it to the binder DLX.

Default: false.

batchingEnabled

Whether to enable message batching by producers.

Default: false.

batchSize

The number of messages to buffer when batching is enabled.

Default: 100.

batchBufferLimit
Default: 10000.
batchTimeout
Default: 5000.
bindingRoutingKey

The routing key with which to bind the queue to the exchange (if bindQueue is true). +Only applies to non-partitioned destinations. +Only applies if requiredGroups are provided and then only to those groups.

Default: #.

bindQueue

Whether to bind the queue to the destination exchange; set to false if you have set up your own infrastructure and have previously created/bound the queue. +Only applies if requiredGroups are provided and then only to those groups.

Default: true.

compress

Whether data should be compressed when sent.

Default: false.

deadLetterQueueName

name of the DLQ +Only applies if requiredGroups are provided and then only to those groups.

Default: prefix+destination.dlq

deadLetterExchange

a DLX to assign to the queue; if autoBindDlq is true +Only applies if requiredGroups are provided and then only to those groups.

Default: 'prefix+DLX'

deadLetterRoutingKey

a dead letter routing key to assign to the queue; if autoBindDlq is true +Only applies if requiredGroups are provided and then only to those groups.

Default: destination

declareExchange

Whether to declare the exchange for the destination.

Default: true.

delay

A SpEL expression to evaluate the delay to apply to the message (x-delay header) - has no effect if the exchange is not a delayed message exchange.

Default: No x-delay header is set.

delayedExchange

Whether to declare the exchange as a Delayed Message Exchange - requires the delayed message exchange plugin on the broker. +The x-delayed-type argument is set to the exchangeType.

Default: false.

deliveryMode

Delivery mode.

Default: PERSISTENT.

dlqDeadLetterExchange

if a DLQ is declared, a DLX to assign to that queue +Only applies if requiredGroups are provided and then only to those groups.

Default: none

dlqDeadLetterRoutingKey

if a DLQ is declared, a dead letter routing key to assign to that queue; default none +Only applies if requiredGroups are provided and then only to those groups.

Default: none

dlqExpires

how long before an unused dead letter queue is deleted (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no expiration

dlqLazy
Declare the dead letter queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Only applies if requiredGroups are provided and then only to those groups.
dlqMaxLength

maximum number of messages in the dead letter queue +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

dlqMaxLengthBytes

maximum number of total bytes in the dead letter queue from all messages +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

dlqMaxPriority

maximum priority of messages in the dead letter queue (0-255) +Only applies if requiredGroups are provided and then only to those groups.

Default: none

dlqTtl

default time to live to apply to the dead letter queue when declared (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

exchangeAutoDelete

If declareExchange is true, whether the exchange should be auto-delete (removed after the last queue is removed).

Default: true.

exchangeDurable

If declareExchange is true, whether the exchange should be durable (survives broker restart).

Default: true.

exchangeType

The exchange type; direct, fanout or topic for non-partitioned destinations; direct or topic for partitioned destinations.

Default: topic.

expires

how long before an unused queue is deleted (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no expiration

headerPatterns

Patterns for headers to be mapped to outbound messages.

Default: ['*'] (all headers).

lazy

Declare the queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Only applies if requiredGroups are provided and then only to those groups.

Default: false.

maxLength

maximum number of messages in the queue +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

maxLengthBytes

maximum number of total bytes in the queue from all messages +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

maxPriority
maximum priority of messages in the queue (0-255) +Only applies if requiredGroups are provided and then only to those groups.
Default
none
prefix

A prefix to be added to the name of the destination exchange.

Default: "".

queueNameGroupOnly

When true, consume from a queue with a name equal to the group; otherwise the queue name is destination.group. +This is useful, for example, when using Spring Cloud Stream to consume from an existing RabbitMQ queue. +Only applies if requiredGroups are provided and then only to those groups.

Default: false.

routingKeyExpression

A SpEL expression to determine the routing key to use when publishing messages. +For a fixed routing key, use a literal expression, e.g. routingKeyExpression='my.routingKey' in a properties file, or routingKeyExpression: '''my.routingKey''' in a YAML file.

Default: destination or destination-<partition> for partitioned destinations.

transacted

Whether to use transacted channels.

Default: false.

ttl

default time to live to apply to the queue when declared (ms) +Only applies if requiredGroups are provided and then only to those groups.

Default: no limit

[Note]Note

In the case of RabbitMQ, content type headers can be set by external applications. +Spring Cloud Stream supports them as part of an extended internal protocol used for any type of transport (including transports, such as Kafka, that do not normally support headers).

38.4 Retry With the RabbitMQ Binder

38.4.1 Overview

When retry is enabled within the binder, the listener container thread is suspended for any back off periods that are configured. +This might be important when strict ordering is required with a single consumer but for other use cases it prevents other messages from being processed on that thread. +An alternative to using binder retry is to set up dead lettering with time to live on the dead-letter queue (DLQ), as well as dead-letter configuration on the DLQ itself. +See Section 38.3.1, “RabbitMQ Binder Properties” for more information about the properties discussed here. +Example configuration to enable this feature:

  • Set autoBindDlq to true - the binder will create a DLQ; you can optionally specify a name in deadLetterQueueName
  • Set dlqTtl to the back off time you want to wait between redeliveries
  • Set the dlqDeadLetterExchange to the default exchange - expired messages from the DLQ will be routed to the original queue since the default deadLetterRoutingKey is the queue name (destination.group)

To force a message to be dead-lettered, either throw an AmqpRejectAndDontRequeueException, or set requeueRejected to true and throw any exception.

The loop will continue without end, which is fine for transient problems but you may want to give up after some number of attempts. +Fortunately, RabbitMQ provides the x-death header which allows you to determine how many cycles have occurred.

To acknowledge a message after giving up, throw an ImmediateAcknowledgeAmqpException.

38.4.2 Putting it All Together

---
+spring.cloud.stream.bindings.input.destination=myDestination
+spring.cloud.stream.bindings.input.group=consumerGroup
+#disable binder retries
+spring.cloud.stream.bindings.input.consumer.max-attempts=1
+#dlx/dlq setup
+spring.cloud.stream.rabbit.bindings.input.consumer.auto-bind-dlq=true
+spring.cloud.stream.rabbit.bindings.input.consumer.dlq-ttl=5000
+spring.cloud.stream.rabbit.bindings.input.consumer.dlq-dead-letter-exchange=
+---

This configuration creates an exchange myDestination with queue myDestination.consumerGroup bound to a topic exchange with a wildcard routing key #. +It creates a DLQ bound to a direct exchange DLX with routing key myDestination.consumerGroup. +When messages are rejected, they are routed to the DLQ. +After 5 seconds, the message expires and is routed to the original queue using the queue name as the routing key.

Spring Boot application.  +

@SpringBootApplication
+@EnableBinding(Sink.class)
+public class XDeathApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(XDeathApplication.class, args);
+    }
+
+    @StreamListener(Sink.INPUT)
+    public void listen(String in, @Header(name = "x-death", required = false) Map<?,?> death) {
+        if (death != null && death.get("count").equals(3L)) {
+            // giving up - don't send to DLX
+            throw new ImmediateAcknowledgeAmqpException("Failed after 4 attempts");
+        }
+        throw new AmqpRejectAndDontRequeueException("failed");
+    }
+
+}

+

Notice that the count property in the x-death header is a Long.

38.5 Error Channels

Starting with version 1.3, the binder unconditionally sends exceptions to an error channel for each consumer destination, and can be configured to send async producer send failures to an error channel too. +See the section called “Message Channel Binders and Error Channels” for more information.

With rabbitmq, there are two types of send failures:

The latter is rare; quoting the RabbitMQ documentation "[A nack] will only be delivered if an internal error occurs in the Erlang process responsible for a queue.".

As well as enabling producer error channels as described in the section called “Message Channel Binders and Error Channels”, the RabbitMQ binder will only send messages to the channels if the connection factory is appropriately configured:

  • ccf.setPublisherConfirms(true);
  • ccf.setPublisherReturns(true);

When using spring boot configuration for the connection factory, set properties:

  • spring.rabbitmq.publisher-confirms
  • spring.rabbitmq.publisher-returns

The payload of the ErrorMessage for a returned message is a ReturnedAmqpMessageException with properties:

  • failedMessage - the spring-messaging Message<?> that failed to be sent.
  • amqpMessage - the raw spring-amqp Message
  • replyCode - an integer value indicating the reason for the failure (e.g. 312 - No route)
  • replyText - a text value indicating the reason for the failure e.g. NO_ROUTE.
  • exchange - the exchange to which the message was published.
  • routingKey - the routing key used when the message was published.

For negatively acknowledged confirms, the payload is a NackedAmqpMessageException with properties:

  • failedMessage - the spring-messaging Message<?> that failed to be sent.
  • nackReason - a reason (if available; you may need to examine the broker logs for more information).

There is no automatic handling of these exceptions (such as sending to a Dead-Letter queue); you can consume these exceptions with your own Spring Integration flow.

38.6 Dead-Letter Queue Processing

Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them. +If the reason for the dead-lettering is transient, you may wish to route the messages back to the original queue. +However, if the problem is a permanent issue, that could cause an infinite loop. +The following spring-boot application is an example of how to route those messages back to the original queue, but moves them to a third "parking lot" queue after three attempts. +The second example utilizes the RabbitMQ Delayed Message Exchange to introduce a delay to the requeued message. +In this example, the delay increases for each attempt. +These examples use a @RabbitListener to receive messages from the DLQ, you could also use RabbitTemplate.receive() in a batch process.

The examples assume the original destination is so8400in and the consumer group is so8400.

38.6.1 Non-Partitioned Destinations

The first two examples are when the destination is not partitioned.

@SpringBootApplication
+public class ReRouteDlqApplication {
+
+    private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+    private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+    private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+    private static final String X_RETRIES_HEADER = "x-retries";
+
+    public static void main(String[] args) throws Exception {
+        ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+        System.out.println("Hit enter to terminate");
+        System.in.read();
+        context.close();
+    }
+
+    @Autowired
+    private RabbitTemplate rabbitTemplate;
+
+    @RabbitListener(queues = DLQ)
+    public void rePublish(Message failedMessage) {
+        Integer retriesHeader = (Integer) failedMessage.getMessageProperties().getHeaders().get(X_RETRIES_HEADER);
+        if (retriesHeader == null) {
+            retriesHeader = Integer.valueOf(0);
+        }
+        if (retriesHeader < 3) {
+            failedMessage.getMessageProperties().getHeaders().put(X_RETRIES_HEADER, retriesHeader + 1);
+            this.rabbitTemplate.send(ORIGINAL_QUEUE, failedMessage);
+        }
+        else {
+            this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+        }
+    }
+
+    @Bean
+    public Queue parkingLot() {
+        return new Queue(PARKING_LOT);
+    }
+
+}
@SpringBootApplication
+public class ReRouteDlqApplication {
+
+    private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+    private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+    private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+    private static final String X_RETRIES_HEADER = "x-retries";
+
+    private static final String DELAY_EXCHANGE = "dlqReRouter";
+
+    public static void main(String[] args) throws Exception {
+        ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+        System.out.println("Hit enter to terminate");
+        System.in.read();
+        context.close();
+    }
+
+    @Autowired
+    private RabbitTemplate rabbitTemplate;
+
+    @RabbitListener(queues = DLQ)
+    public void rePublish(Message failedMessage) {
+        Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
+        Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
+        if (retriesHeader == null) {
+            retriesHeader = Integer.valueOf(0);
+        }
+        if (retriesHeader < 3) {
+            headers.put(X_RETRIES_HEADER, retriesHeader + 1);
+            headers.put("x-delay", 5000 * retriesHeader);
+            this.rabbitTemplate.send(DELAY_EXCHANGE, ORIGINAL_QUEUE, failedMessage);
+        }
+        else {
+            this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+        }
+    }
+
+    @Bean
+    public DirectExchange delayExchange() {
+        DirectExchange exchange = new DirectExchange(DELAY_EXCHANGE);
+        exchange.setDelayed(true);
+        return exchange;
+    }
+
+    @Bean
+    public Binding bindOriginalToDelay() {
+        return BindingBuilder.bind(new Queue(ORIGINAL_QUEUE)).to(delayExchange()).with(ORIGINAL_QUEUE);
+    }
+
+    @Bean
+    public Queue parkingLot() {
+        return new Queue(PARKING_LOT);
+    }
+
+}

38.6.2 Partitioned Destinations

With partitioned destinations, there is one DLQ for all partitions and we determine the original queue from the headers.

republishToDlq=false

When republishToDlq is false, RabbitMQ publishes the message to the DLX/DLQ with an x-death header containing information about the original destination.

@SpringBootApplication
+public class ReRouteDlqApplication {
+
+	private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+	private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+	private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+	private static final String X_DEATH_HEADER = "x-death";
+
+	private static final String X_RETRIES_HEADER = "x-retries";
+
+	public static void main(String[] args) throws Exception {
+		ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+		System.out.println("Hit enter to terminate");
+		System.in.read();
+		context.close();
+	}
+
+	@Autowired
+	private RabbitTemplate rabbitTemplate;
+
+	@SuppressWarnings("unchecked")
+	@RabbitListener(queues = DLQ)
+	public void rePublish(Message failedMessage) {
+		Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
+		Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
+		if (retriesHeader == null) {
+			retriesHeader = Integer.valueOf(0);
+		}
+		if (retriesHeader < 3) {
+			headers.put(X_RETRIES_HEADER, retriesHeader + 1);
+			List<Map<String, ?>> xDeath = (List<Map<String, ?>>) headers.get(X_DEATH_HEADER);
+			String exchange = (String) xDeath.get(0).get("exchange");
+			List<String> routingKeys = (List<String>) xDeath.get(0).get("routing-keys");
+			this.rabbitTemplate.send(exchange, routingKeys.get(0), failedMessage);
+		}
+		else {
+			this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+		}
+	}
+
+	@Bean
+	public Queue parkingLot() {
+		return new Queue(PARKING_LOT);
+	}
+
+}

republishToDlq=true

When republishToDlq is true, the republishing recoverer adds the original exchange and routing key to headers.

@SpringBootApplication
+public class ReRouteDlqApplication {
+
+	private static final String ORIGINAL_QUEUE = "so8400in.so8400";
+
+	private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
+
+	private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
+
+	private static final String X_RETRIES_HEADER = "x-retries";
+
+	private static final String X_ORIGINAL_EXCHANGE_HEADER = RepublishMessageRecoverer.X_ORIGINAL_EXCHANGE;
+
+	private static final String X_ORIGINAL_ROUTING_KEY_HEADER = RepublishMessageRecoverer.X_ORIGINAL_ROUTING_KEY;
+
+	public static void main(String[] args) throws Exception {
+		ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
+		System.out.println("Hit enter to terminate");
+		System.in.read();
+		context.close();
+	}
+
+	@Autowired
+	private RabbitTemplate rabbitTemplate;
+
+	@RabbitListener(queues = DLQ)
+	public void rePublish(Message failedMessage) {
+		Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
+		Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
+		if (retriesHeader == null) {
+			retriesHeader = Integer.valueOf(0);
+		}
+		if (retriesHeader < 3) {
+			headers.put(X_RETRIES_HEADER, retriesHeader + 1);
+			String exchange = (String) headers.get(X_ORIGINAL_EXCHANGE_HEADER);
+			String originalRoutingKey = (String) headers.get(X_ORIGINAL_ROUTING_KEY_HEADER);
+			this.rabbitTemplate.send(exchange, originalRoutingKey, failedMessage);
+		}
+		else {
+			this.rabbitTemplate.send(PARKING_LOT, failedMessage);
+		}
+	}
+
+	@Bean
+	public Queue parkingLot() {
+		return new Queue(PARKING_LOT);
+	}
+
+}

Part VI. Spring Cloud Bus

Spring Cloud Bus links nodes of a distributed system with a lightweight message broker. This can then be used to broadcast state changes (e.g. configuration changes) or other management instructions. A key idea is that the Bus is like a distributed Actuator for a Spring Boot application that is scaled out, but it can also be used as a communication channel between apps. Starters are provided for an AMQP broker as the transport or for Kafka, but the same basic feature set (and some more depending on the transport) is on the roadmap for other transports.

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

39. Quick Start

Spring Cloud Bus works by adding Spring Boot autconfiguration if it detects itself on the classpath. All you need to do to enable the bus is to add spring-cloud-starter-bus-amqp or spring-cloud-starter-bus-kafka to your dependency management and Spring Cloud takes care of the rest. Make sure the broker (RabbitMQ or Kafka) is available and configured: running on localhost you shouldn’t have to do anything, but if you are running remotely use Spring Cloud Connectors, or Spring Boot conventions to define the broker credentials, e.g. for Rabbit

application.yml.  +

spring:
+  rabbitmq:
+    host: mybroker.com
+    port: 5672
+    username: user
+    password: secret

+

The bus currently supports sending messages to all nodes listening or all nodes for a particular service (as defined by Eureka). More selector criteria may be added in the future (ie. only service X nodes in data center Y, etc…​). There are also some http endpoints under the /bus/* actuator namespace. There are currently two implemented. The first, /bus/env, sends key/value pairs to update each node’s Spring Environment. The second, /bus/refresh, will reload each application’s configuration, just as if they had all been pinged on their /refresh endpoint.

[Note]Note

The Bus starters cover Rabbit and Kafka, because those are the two most common implementations, but Spring Cloud Stream is quite flexible and binder will work combined with spring-cloud-bus.

40. Addressing an Instance

The HTTP endpoints accept a "destination" parameter, e.g. "/bus/refresh?destination=customers:9000", where the destination is an ApplicationContext ID. If the ID is owned by an instance on the Bus then it will process the message and all other instances will ignore it. Spring Boot sets the ID for you in the ContextIdApplicationContextInitializer to a combination of the spring.application.name, active profiles and server.port by default.

41. Addressing all instances of a service

The "destination" parameter is used in a Spring PathMatcher (with the path separator as a colon :) to determine if an instance will process the message. Using the example from above, "/bus/refresh?destination=customers:**" will target all instances of the "customers" service regardless of the profiles and ports set as the ApplicationContext ID.

42. Application Context ID must be unique

The bus tries to eliminate processing an event twice, once from the original ApplicationEvent and once from the queue. To do this, it checks the sending application context id againts the current application context id. If multiple instances of a service have the same application context id, events will not be processed. Running on a local machine, each service will be on a different port and that will be part of the application context id. Cloud Foundry supplies an index to differentiate. To ensure that the application context id is the unique, set spring.application.index to something unique for each instance of a service. For example, in lattice, set spring.application.index=${INSTANCE_INDEX} in application.properties (or bootstrap.properties if using configserver).

43. Customizing the Message Broker

Spring Cloud Bus uses +Spring Cloud Stream to +broadcast the messages so to get messages to flow you only need to +include the binder implementation of your choice in the +classpath. There are convenient starters specifically for the bus with +AMQP (RabbitMQ) and Kafka +(spring-cloud-starter-bus-[amqp,kafka]). Generally speaking +Spring Cloud Stream relies on Spring Boot autoconfiguration +conventions for configuring middleware, so for instance the AMQP +broker address can be changed with spring.rabbitmq.* +configuration properties. Spring Cloud Bus has a handful of native +configuration properties in spring.cloud.bus.* +(e.g. spring.cloud.bus.destination is the name of the topic to use +the the externall middleware). Normally the defaults will suffice.

To lean more about how to customize the message broker settings +consult the Spring Cloud Stream documentation.

44. Tracing Bus Events

Bus events (subclasses of RemoteApplicationEvent) can be traced by +setting spring.cloud.bus.trace.enabled=true. If you do this then the +Spring Boot TraceRepository (if it is present) will show each event +sent and all the acks from each service instance. Example (from the +/trace endpoint):

{
+  "timestamp": "2015-11-26T10:24:44.411+0000",
+  "info": {
+    "signal": "spring.cloud.bus.ack",
+    "type": "RefreshRemoteApplicationEvent",
+    "id": "c4d374b7-58ea-4928-a312-31984def293b",
+    "origin": "stores:8081",
+    "destination": "*:**"
+  }
+  },
+  {
+  "timestamp": "2015-11-26T10:24:41.864+0000",
+  "info": {
+    "signal": "spring.cloud.bus.sent",
+    "type": "RefreshRemoteApplicationEvent",
+    "id": "c4d374b7-58ea-4928-a312-31984def293b",
+    "origin": "customers:9000",
+    "destination": "*:**"
+  }
+  },
+  {
+  "timestamp": "2015-11-26T10:24:41.862+0000",
+  "info": {
+    "signal": "spring.cloud.bus.ack",
+    "type": "RefreshRemoteApplicationEvent",
+    "id": "c4d374b7-58ea-4928-a312-31984def293b",
+    "origin": "customers:9000",
+    "destination": "*:**"
+  }
+}

This trace shows that a RefreshRemoteApplicationEvent was sent from +customers:9000, broadcast to all services, and it was received +(acked) by customers:9000 and stores:8081.

To handle the ack signals yourself you could add an @EventListener +for the AckRemoteApplicationEvent and SentApplicationEvent types +to your app (and enable tracing). Or you could tap into the +TraceRepository and mine the data from there.

[Note]Note

Any Bus application can trace acks, but sometimes it will be +useful to do this in a central service that can do more complex +queries on the data. Or forward it to a specialized tracing service.

45. Broadcasting Your Own Events

The Bus can carry any event of type RemoteApplicationEvent, but the +default transport is JSON and the deserializer needs to know which +types are going to be used ahead of time. To register a new type it +needs to be in a subpackage of org.springframework.cloud.bus.event.

To customise the event name you can use @JsonTypeName on your custom class +or rely on the default strategy which is to use the simple name of the class. +Note that both the producer and the consumer will need access to the class +definition.

45.1 Registering events in custom packages

If you cannot or don’t want to use a subpackage of org.springframework.cloud.bus.event +for your custom events, you must specify which packages to scan for events of +type RemoteApplicationEvent using @RemoteApplicationEventScan. Packages +specified with @RemoteApplicationEventScan include subpackages.

For example, if you have a custom event called FooEvent:

package com.acme;
+
+public class FooEvent extends RemoteApplicationEvent {
+    ...
+}

you can register this event with the deserializer in the following way:

package com.acme;
+
+@Configuration
+@RemoteApplicationEventScan
+public class BusConfiguration {
+    ...
+}

Without specifying a value, the package of the class where @RemoteApplicationEventScan +is used will be registered. In this example com.acme will be registered using the +package of BusConfiguration.

You can also explicitly specify the packages to scan using the value, basePackages or +basePackageClasses properties on @RemoteApplicationEventScan. For example:

package com.acme;
+
+@Configuration
+//@RemoteApplicationEventScan({"com.acme", "foo.bar"})
+//@RemoteApplicationEventScan(basePackages = {"com.acme", "foo.bar", "fizz.buzz"})
+@RemoteApplicationEventScan(basePackageClasses = BusConfiguration.class)
+public class BusConfiguration {
+    ...
+}

All examples of @RemoteApplicationEventScan above are equivalent, +in that the com.acme package will be registered by explicitly specifying the +packages on @RemoteApplicationEventScan. Note, you can specify multiple base +packages to scan.

Part VII. Spring Cloud Sleuth

Adrian Cole, Spencer Gibb, Marcin Grzejszczak, Dave Syer

1.3.8.RELEASE

46. Introduction

Spring Cloud Sleuth implements a distributed tracing solution for Spring Cloud.

46.1 Terminology

Spring Cloud Sleuth borrows Dapper’s terminology.

Span: The basic unit of work. For example, sending an RPC is a new span, as is sending a response to an +RPC. Span’s are identified by a unique 64-bit ID for the span and another 64-bit ID for the trace the span +is a part of. Spans also have other data, such as descriptions, timestamped events, key-value +annotations (tags), the ID of the span that caused them, and process ID’s (normally IP address).

Spans are started and stopped, and they keep track of their timing information. Once you create a +span, you must stop it at some point in the future.

[Tip]Tip

The initial span that starts a trace is called a root span. The value of span id +of that span is equal to trace id.

Trace: A set of spans forming a tree-like structure. For example, if you are running a distributed +big-data store, a trace might be formed by a put request.

Annotation: is used to record existence of an event in time. Some of the core annotations used to define +the start and stop of a request are:

  • cs - Client Sent - The client has made a request. This annotation depicts the start of the span.
  • sr - Server Received - The server side got the request and will start processing it. +If one subtracts the cs timestamp from this timestamp one will receive the network latency.
  • ss - Server Sent - Annotated upon completion of request processing (when the response +got sent back to the client). If one subtracts the sr timestamp from this timestamp one +will receive the time needed by the server side to process the request.
  • cr - Client Received - Signifies the end of the span. The client has successfully received the +response from the server side. If one subtracts the cs timestamp from this timestamp one +will receive the whole time needed by the client to receive the response from the server.

Visualization of what Span and Trace will look in a system together with the Zipkin annotations:

Trace Info propagation

Each color of a note signifies a span (7 spans - from A to G). If you have such information in the note:

Trace Id = X
+Span Id = D
+Client Sent

That means that the current span has Trace-Id set to X, Span-Id set to D. It also has emitted + Client Sent event.

This is how the visualization of the parent / child relationship of spans would look like:

Parent child relationship

46.2 Purpose

In the following sections the example from the image above will be taken into consideration.

46.2.1 Distributed tracing with Zipkin

Altogether there are 7 spans . If you go to traces in Zipkin you will see this number in the second trace:

Traces

However if you pick a particular trace then you will see 4 spans:

Traces Info propagation
[Note]Note

When picking a particular trace you will see merged spans. That means that if there were 2 spans sent to +Zipkin with Server Received and Server Sent / Client Received and Client Sent +annotations then they will presented as a single span.

Why is there a difference between the 7 and 4 spans in this case?

  • 2 spans come from http:/start span. It has the Server Received (SR) and Server Sent (SS) annotations.
  • 2 spans come from the RPC call from service1 to service2 to the http:/foo endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service1 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service2 side. Physically there are 2 spans but they form 1 logical span related to an RPC call.
  • 2 spans come from the RPC call from service2 to service3 to the http:/bar endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service2 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service3 side. Physically there are 2 spans but they form 1 logical span related to an RPC call.
  • 2 spans come from the RPC call from service2 to service4 to the http:/baz endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service2 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service4 side. Physically there are 2 spans but they form 1 logical span related to an RPC call.

So if we count the physical spans we have 1 from http:/start, 2 from service1 calling service2, 2 form service2 +calling service3 and 2 from service2 calling service4. Altogether 7 spans.

Logically we see the information of Total Spans: 4 because we have 1 span related to the incoming request +to service1 and 3 spans related to RPC calls.

46.2.2 Visualizing errors

Zipkin allows you to visualize errors in your trace. When an exception was thrown and wasn’t caught then we’re +setting proper tags on the span which Zipkin can properly colorize. You could see in the list of traces one + trace that was in red color. That’s because there was an exception thrown.

If you click that trace then you’ll see a similar picture

Error Traces

Then if you click on one of the spans you’ll see the following

Error Traces Info propagation

As you can see you can easily see the reason for an error and the whole stacktrace related to it.

46.2.3 Live examples

Figure 46.1. Click Pivotal Web Services icon to see it live!

Zipkin deployed on Pivotal Web Services

The dependency graph in Zipkin would look like this:

Dependencies

Figure 46.2. Click Pivotal Web Services icon to see it live!

Zipkin deployed on Pivotal Web Services

46.2.4 Log correlation

When grepping the logs of those four applications by trace id equal to e.g. 2485ec27856c56f4 one would get the following:

service1.log:2016-02-26 11:15:47.561  INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application   : Hello from service1. Calling service2
+service2.log:2016-02-26 11:15:47.710  INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application   : Hello from service2. Calling service3 and then service4
+service3.log:2016-02-26 11:15:47.895  INFO [service3,2485ec27856c56f4,1210be13194bfe5,true] 68060 --- [nio-8083-exec-1] i.s.c.sleuth.docs.service3.Application   : Hello from service3
+service2.log:2016-02-26 11:15:47.924  INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application   : Got response from service3 [Hello from service3]
+service4.log:2016-02-26 11:15:48.134  INFO [service4,2485ec27856c56f4,1b1845262ffba49d,true] 68061 --- [nio-8084-exec-1] i.s.c.sleuth.docs.service4.Application   : Hello from service4
+service2.log:2016-02-26 11:15:48.156  INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application   : Got response from service4 [Hello from service4]
+service1.log:2016-02-26 11:15:48.182  INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application   : Got response from service2 [Hello from service2, response from service3 [Hello from service3] and from service4 [Hello from service4]]

If you’re using a log aggregating tool like Kibana, +Splunk etc. you can order the events that took place. An example of +Kibana would look like this:

Log correlation with Kibana

If you want to use Logstash here is the Grok pattern for Logstash:

filter {
+       # pattern matching logback pattern
+       grok {
+              match => { "message" => "%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
+       }
+}
[Note]Note

If you want to use Grok together with the logs from Cloud Foundry you have to use this pattern:

filter {
+       # pattern matching logback pattern
+       grok {
+              match => { "message" => "(?m)OUT\s+%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
+       }
+}

JSON Logback with Logstash

Often you do not want to store your logs in a text file but in a JSON file that Logstash can immediately pick. To do that you have to do the following (for readability +we’re passing the dependencies in the groupId:artifactId:version notation.

Dependencies setup

  • Ensure that Logback is on the classpath (ch.qos.logback:logback-core)
  • Add Logstash Logback encode - example for version 4.6 : net.logstash.logback:logstash-logback-encoder:4.6

Logback setup

Below you can find an example of a Logback configuration (file named logback-spring.xml) that:

  • logs information from the application in a JSON format to a build/${spring.application.name}.json file
  • has commented out two additional appenders - console and standard log file
  • has the same logging pattern as the one presented in the previous section
<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+	<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
+	​
+	<springProperty scope="context" name="springAppName" source="spring.application.name"/>
+	<!-- Example for logging into the build folder of your project -->
+	<property name="LOG_FILE" value="${BUILD_FOLDER:-build}/${springAppName}"/>​
+
+	<!-- You can override this to have a custom pattern -->
+	<property name="CONSOLE_LOG_PATTERN"
+			  value="%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}"/>
+
+	<!-- Appender to log to console -->
+	<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
+		<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
+			<!-- Minimum logging level to be presented in the console logs-->
+			<level>DEBUG</level>
+		</filter>
+		<encoder>
+			<pattern>${CONSOLE_LOG_PATTERN}</pattern>
+			<charset>utf8</charset>
+		</encoder>
+	</appender>
+
+	<!-- Appender to log to file -->​
+	<appender name="flatfile" class="ch.qos.logback.core.rolling.RollingFileAppender">
+		<file>${LOG_FILE}</file>
+		<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+			<fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.gz</fileNamePattern>
+			<maxHistory>7</maxHistory>
+		</rollingPolicy>
+		<encoder>
+			<pattern>${CONSOLE_LOG_PATTERN}</pattern>
+			<charset>utf8</charset>
+		</encoder>
+	</appender>
+	​
+	<!-- Appender to log to file in a JSON format -->
+	<appender name="logstash" class="ch.qos.logback.core.rolling.RollingFileAppender">
+		<file>${LOG_FILE}.json</file>
+		<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+			<fileNamePattern>${LOG_FILE}.json.%d{yyyy-MM-dd}.gz</fileNamePattern>
+			<maxHistory>7</maxHistory>
+		</rollingPolicy>
+		<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
+			<providers>
+				<timestamp>
+					<timeZone>UTC</timeZone>
+				</timestamp>
+				<pattern>
+					<pattern>
+						{
+						"severity": "%level",
+						"service": "${springAppName:-}",
+						"trace": "%X{X-B3-TraceId:-}",
+						"span": "%X{X-B3-SpanId:-}",
+						"parent": "%X{X-B3-ParentSpanId:-}",
+						"exportable": "%X{X-Span-Export:-}",
+						"pid": "${PID:-}",
+						"thread": "%thread",
+						"class": "%logger{40}",
+						"rest": "%message"
+						}
+					</pattern>
+				</pattern>
+			</providers>
+		</encoder>
+	</appender>
+	​
+	<root level="INFO">
+		<appender-ref ref="console"/>
+		<!-- uncomment this to have also JSON logs -->
+		<!--<appender-ref ref="logstash"/>-->
+		<!--<appender-ref ref="flatfile"/>-->
+	</root>
+</configuration>
[Note]Note

If you’re using a custom logback-spring.xml then you have to pass the spring.application.name in +bootstrap instead of application property file. Otherwise your custom logback file won’t read the property properly.

46.2.5 Propagating Span Context

The span context is the state that must get propagated to any child Spans across process boundaries. +Part of the Span Context is the Baggage. The trace and span IDs are a required part of the span context. +Baggage is an optional part.

Baggage is a set of key:value pairs stored in the span context. Baggage travels together with the trace +and is attached to every span. Spring Cloud Sleuth will understand that a header is baggage related if the HTTP + header is prefixed with baggage- and for messaging it starts with baggage_.

[Important]Important

There’s currently no limitation of the count or size of baggage items. However, keep in mind that +too many can decrease system throughput or increase RPC latency. In extreme cases, it could crash the app due +to exceeding transport-level message or header capacity.

Example of setting baggage on a span:

Span initialSpan = this.tracer.createSpan("span");
+initialSpan.setBaggageItem("foo", "bar");
+initialSpan.setBaggageItem("UPPER_CASE", "someValue");

Baggage vs. Span Tags

Baggage travels with the trace (i.e. every child span contains the baggage of its parent). Zipkin has no knowledge of +baggage and will not even receive that information.

Tags are attached to a specific span - they are presented for that particular span only. However you +can search by tag to find the trace, where there exists a span having the searched tag value.

If you want to be able to lookup a span based on baggage, you should add corresponding entry as a tag in the root span.

@Autowired Tracer tracer;
+
+Span span = tracer.getCurrentSpan();
+String baggageKey = "key";
+String baggageValue = "foo";
+span.setBaggageItem(baggageKey, baggageValue);
+tracer.addTag(baggageKey, baggageValue);

46.3 Adding to the project

[Important]Important

To ensure that your application name is properly displayed in Zipkin + set the spring.application.name property in bootstrap.yml.

46.3.1 Only Sleuth (log correlation)

If you want to profit only from Spring Cloud Sleuth without the Zipkin integration just add +the spring-cloud-starter-sleuth module to your project.

Maven.  +

<dependencyManagement> 1
+         <dependencies>
+             <dependency>
+                 <groupId>org.springframework.cloud</groupId>
+                 <artifactId>spring-cloud-dependencies</artifactId>
+                 <version>${release.train.version}</version>
+                 <type>pom</type>
+                 <scope>import</scope>
+             </dependency>
+         </dependencies>
+   </dependencyManagement>
+
+   <dependency> 2
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-starter-sleuth</artifactId>
+   </dependency>

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-sleuth

Gradle.  +

dependencyManagement { 1
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
+    }
+}
+
+dependencies { 2
+    compile "org.springframework.cloud:spring-cloud-starter-sleuth"
+}

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-sleuth

46.3.2 Sleuth with Zipkin via HTTP

If you want both Sleuth and Zipkin just add the spring-cloud-starter-zipkin dependency.

Maven.  +

<dependencyManagement> 1
+         <dependencies>
+             <dependency>
+                 <groupId>org.springframework.cloud</groupId>
+                 <artifactId>spring-cloud-dependencies</artifactId>
+                 <version>${release.train.version}</version>
+                 <type>pom</type>
+                 <scope>import</scope>
+             </dependency>
+         </dependencies>
+   </dependencyManagement>
+
+   <dependency> 2
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-starter-zipkin</artifactId>
+   </dependency>

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin

Gradle.  +

dependencyManagement { 1
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
+    }
+}
+
+dependencies { 2
+    compile "org.springframework.cloud:spring-cloud-starter-zipkin"
+}

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin

46.3.3 Sleuth with Zipkin via RabbitMQ or Kafka

If you want to use RabbitMQ or Kafka instead of http, add the spring-rabbit or spring-kafka +dependencies. The default destination name is zipkin.

Note: spring-cloud-sleuth-stream is deprecated and incompatible with these destinations

If you want Sleuth over RabbitMQ add the spring-cloud-starter-zipkin and spring-rabbit +dependencies.

Maven.  +

<dependencyManagement> 1
+         <dependencies>
+             <dependency>
+                 <groupId>org.springframework.cloud</groupId>
+                 <artifactId>spring-cloud-dependencies</artifactId>
+                 <version>${release.train.version}</version>
+                 <type>pom</type>
+                 <scope>import</scope>
+             </dependency>
+         </dependencies>
+   </dependencyManagement>
+
+   <dependency> 2
+       <groupId>org.springframework.cloud</groupId>
+       <artifactId>spring-cloud-starter-zipkin</artifactId>
+   </dependency>
+   <dependency> 3
+       <groupId>org.springframework.amqp</groupId>
+       <artifactId>spring-rabbit</artifactId>
+   </dependency>

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin - that way all dependent dependencies will be downloaded

3

To automatically configure rabbit, simply add the spring-rabbit dependency

Gradle.  +

dependencyManagement { 1
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
+    }
+}
+
+dependencies {
+    compile "org.springframework.cloud:spring-cloud-starter-zipkin" 2
+    compile "org.springframework.amqp:spring-rabbit" 3
+}

+

1

In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM

2

Add the dependency to spring-cloud-starter-zipkin - that way all dependent dependencies will be downloaded

3

To automatically configure rabbit, simply add the spring-rabbit dependency

47. Additional resources

Marcin Grzejszczak talking about Spring Cloud Sleuth and Zipkin

click here to see the video

48. Features

  • Adds trace and span ids to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator. Example logs:

    2016-02-02 15:30:57.902  INFO [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ...
+2016-02-02 15:30:58.372 ERROR [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ...
+2016-02-02 15:31:01.936  INFO [bar,46ab0d418373cbc9,46ab0d418373cbc9,false] 23030 --- [nio-8081-exec-4] ...

    notice the [appname,traceId,spanId,exportable] entries from the MDC:

    • spanId - the id of a specific operation that took place
    • appname - the name of the application that logged the span
    • traceId - the id of the latency graph that contains the span
    • exportable - whether the log should be exported to Zipkin or not. When would you like the span not to be +exportable? In the case in which you want to wrap some operation in a Span and have it written to the logs +only.
  • Provides an abstraction over common distributed tracing data models: traces, spans (forming a DAG), annotations, +key-value annotations. Loosely based on HTrace, but Zipkin (Dapper) compatible.

  • Sleuth records timing information to aid in latency analysis. Using sleuth, you can pinpoint causes of +latency in your applications. Sleuth is written to not log too much, and to not cause your production application to crash.

    • propagates structural data about your call-graph in-band, and the rest out-of-band.
    • includes opinionated instrumentation of layers such as HTTP
    • includes sampling policy to manage volume
    • can report to a Zipkin system for query and visualization
  • Instruments common ingress and egress points from Spring applications (servlet filter, async endpoints, +rest template, scheduled actions, message channels, zuul filters, feign client).
  • Sleuth includes default logic to join a trace across http or messaging boundaries. For example, http propagation +works via Zipkin-compatible request headers. This propagation logic is defined and customized via +SpanInjector and SpanExtractor implementations.
  • Sleuth gives you the possibility to propagate context (also known as baggage) between processes. That means that if you set on a Span +a baggage element then it will be sent downstream either via HTTP or messaging to other processes.
  • Provides a way to create / continue spans and add tags and logs via annotations.
  • Provides simple metrics of accepted / dropped spans.

  • If spring-cloud-sleuth-zipkin is on the classpath then the app will generate and collect Zipkin-compatible traces. +By default it sends them via HTTP to a Zipkin server on localhost (port 9411). +Configure the location of the service using spring.zipkin.baseUrl.

    • If you depend on spring-rabbit or spring-kafka your app will send traces to a broker instead of http.
    • Note: spring-cloud-sleuth-stream is deprecated and should no longer be used.
[Important]Important

If using Zipkin, configure the percentage of spans exported using spring.sleuth.sampler.percentage +(default 0.1, i.e. 10%). Otherwise you might think that Sleuth is not working cause it’s omitting some spans.

[Note]Note

the SLF4J MDC is always set and logback users will immediately see the trace and span ids in logs per the example + above. Other logging systems have to configure their own formatter to get the same result. The default is + logging.pattern.level set to %5p [${spring.zipkin.service.name:${spring.application.name:-}},%X{X-B3-TraceId:-},%X{X-B3-SpanId:-},%X{X-Span-Export:-}] + (this is a Spring Boot feature for logback users). + This means that if you’re not using SLF4J this pattern WILL NOT be automatically applied.

49. Sampling

In distributed tracing the data volumes can be very high so sampling +can be important (you usually don’t need to export all spans to get a +good picture of what is happening). Spring Cloud Sleuth has a +Sampler strategy that you can implement to take control of the +sampling algorithm. Samplers do not stop span (correlation) ids from +being generated, but they do prevent the tags and events being +attached and exported. By default you get a strategy that continues to +trace if a span is already active, but new ones are always marked as +non-exportable. If all your apps run with this sampler you will see +traces in logs, but not in any remote store. For testing the default +is often enough, and it probably is all you need if you are only using +the logs (e.g. with an ELK aggregator). If you are exporting span data +to Zipkin or Spring Cloud Stream, there is also an AlwaysSampler +that exports everything and a PercentageBasedSampler that samples a +fixed fraction of spans.

[Note]Note

the PercentageBasedSampler is the default if you are using +spring-cloud-sleuth-zipkin or spring-cloud-sleuth-stream. You can +configure the exports using spring.sleuth.sampler.percentage. The passed +value needs to be a double from 0.0 to 1.0 so it’s not a percentage. +For backwards compatibility reasons we’re not changing the property name.

A sampler can be installed just by creating a bean definition, e.g:

@Bean
+public Sampler defaultSampler() {
+	return new AlwaysSampler();
+}
[Tip]Tip

You can set the HTTP header X-B3-Flags to 1 or when doing messaging you can +set spanFlags header to 1. Then the current span will be forced to be exportable +regardless of the sampling decision.

50. Instrumentation

Spring Cloud Sleuth instruments all your Spring application +automatically, so you shouldn’t have to do anything to activate +it. The instrumentation is added using a variety of technologies +according to the stack that is available, e.g. for a servlet web +application we use a Filter, and for Spring Integration we use +ChannelInterceptors.

You can customize the keys used in span tags. To limit the volume of +span data, by default an HTTP request will be tagged only with a +handful of metadata like the status code, host and URL. You can add +request headers by configuring spring.sleuth.keys.http.headers (a +list of header names).

[Note]Note

Remember that tags are only collected and exported if there is a +Sampler that allows it (by default there is not, so there is no +danger of accidentally collecting too much data without configuring +something).

[Note]Note

Currently the instrumentation in Spring Cloud Sleuth is eager - it means that +we’re actively trying to pass the tracing context between threads. Also timing events +are captured even when sleuth isn’t exporting data to a tracing system. +This approach may change in the future towards being lazy on this matter.

51. Span lifecycle

You can do the following operations on the Span by means of org.springframework.cloud.sleuth.Tracer interface:

  • start - when you start a span its name is assigned and start timestamp is recorded.
  • close - the span gets finished (the end time of the span is recorded) and if +the span is exportable then it will be eligible for collection to Zipkin. +The span is also removed from the current thread.
  • continue - a new instance of span will be created whereas it will be a copy of the +one that it continues.
  • detach - the span doesn’t get stopped or closed. It only gets removed from the current thread.
  • create with explicit parent - you can create a new span and set an explicit parent to it
[Tip]Tip

Spring creates the instance of Tracer for you. In order to use it all you need is to just autowire it.

51.1 Creating and closing spans

You can manually create spans by using the Tracer interface.

// Start a span. If there was a span present in this thread it will become
+// the `newSpan`'s parent.
+Span newSpan = this.tracer.createSpan("calculateTax");
+try {
+	// ...
+	// You can tag a span
+	this.tracer.addTag("taxValue", taxValue);
+	// ...
+	// You can log an event on a span
+	newSpan.logEvent("taxCalculated");
+} finally {
+	// Once done remember to close the span. This will allow collecting
+	// the span to send it to Zipkin
+	this.tracer.close(newSpan);
+}

In this example we could see how to create a new instance of span. Assuming that there already +was a span present in this thread then it would become the parent of that span.

[Important]Important

Always clean after you create a span! Don’t forget to close a span if you want to send it to Zipkin.

[Important]Important

If your span contains a name greater than 50 chars, then that name will +be truncated to 50 chars. Your names have to be explicit and concrete. Big names lead to +latency issues and sometimes even thrown exceptions.

51.2 Continuing spans

Sometimes you don’t want to create a new span but you want to continue one. Example of such a +situation might be (of course it all depends on the use-case):

  • AOP - If there was already a span created before an aspect was reached then you might not want to create a new span.
  • Hystrix - executing a Hystrix command is most likely a logical part of the current processing. It’s in fact +only a technical implementation detail that you wouldn’t necessarily want to reflect in tracing as a separate being.

The continued instance of span is equal to the one that it continues:

Span continuedSpan = this.tracer.continueSpan(spanToContinue);
+assertThat(continuedSpan).isEqualTo(spanToContinue);

To continue a span you can use the Tracer interface.

// let's assume that we're in a thread Y and we've received
+// the `initialSpan` from thread X
+Span continuedSpan = this.tracer.continueSpan(initialSpan);
+try {
+	// ...
+	// You can tag a span
+	this.tracer.addTag("taxValue", taxValue);
+	// ...
+	// You can log an event on a span
+	continuedSpan.logEvent("taxCalculated");
+} finally {
+	// Once done remember to detach the span. That way you'll
+	// safely remove it from the current thread without closing it
+	this.tracer.detach(continuedSpan);
+}
[Important]Important

Always clean after you create a span! Don’t forget to detach a span if some work was done started in one + thread (e.g. thread X) and it’s waiting for other threads (e.g. Y, Z) to finish. + Then the spans in the threads Y, Z should be detached at the end of their work. When the results are collected + the span in thread X should be closed.

51.3 Creating spans with an explicit parent

There is a possibility that you want to start a new span and provide an explicit parent of that span. +Let’s assume that the parent of a span is in one thread and you want to start a new span in another thread. The +startSpan method of the Tracer interface is the method you are looking for.

// let's assume that we're in a thread Y and we've received
+// the `initialSpan` from thread X. `initialSpan` will be the parent
+// of the `newSpan`
+Span newSpan = this.tracer.createSpan("calculateCommission", initialSpan);
+try {
+	// ...
+	// You can tag a span
+	this.tracer.addTag("commissionValue", commissionValue);
+	// ...
+	// You can log an event on a span
+	newSpan.logEvent("commissionCalculated");
+} finally {
+	// Once done remember to close the span. This will allow collecting
+	// the span to send it to Zipkin. The tags and events set on the
+	// newSpan will not be present on the parent
+	this.tracer.close(newSpan);
+}
[Important]Important

After having created such a span remember to close it. Otherwise you will see a lot of warnings in your logs + related to the fact that you have a span present in the current thread other than the one you’re trying to close. + What’s worse your spans won’t get closed properly thus will not get collected to Zipkin.

52. Naming spans

Picking a span name is not a trivial task. Span name should depict an operation name. The name should +be low cardinality (e.g. not include identifiers).

Since there is a lot of instrumentation going on some of the span names will be +artificial like:

  • controller-method-name when received by a Controller with a method name conrollerMethodName
  • async for asynchronous operations done via wrapped Callable and Runnable.
  • @Scheduled annotated methods will return the simple name of the class.

Fortunately, for the asynchronous processing you can provide explicit naming.

52.1 @SpanName annotation

You can name the span explicitly via the @SpanName annotation.

@SpanName("calculateTax")
+class TaxCountingRunnable implements Runnable {
+
+	@Override public void run() {
+		// perform logic
+	}
+}

In this case, when processed in the following manner:

Runnable runnable = new TraceRunnable(tracer, spanNamer, new TaxCountingRunnable());
+Future<?> future = executorService.submit(runnable);
+// ... some additional logic ...
+future.get();

The span will be named calculateTax.

52.2 toString() method

It’s pretty rare to create separate classes for Runnable or Callable. Typically one creates an anonymous +instance of those classes. You can’t annotate such classes thus to override that, if there is no @SpanName annotation present, +we’re checking if the class has a custom implementation of the toString() method.

So executing such code:

Runnable runnable = new TraceRunnable(tracer, spanNamer, new Runnable() {
+	@Override public void run() {
+		// perform logic
+	}
+
+	@Override public String toString() {
+		return "calculateTax";
+	}
+});
+Future<?> future = executorService.submit(runnable);
+// ... some additional logic ...
+future.get();

will lead in creating a span named calculateTax.

53. Managing spans with annotations

53.1 Rationale

The main arguments for this features are

  • api-agnostic means to collaborate with a span

    • use of annotations allows users to add to a span with no library dependency on a span api. +This allows Sleuth to change its core api less impact to user code.

  • reduced surface area for basic span operations.

    • without this feature one has to use the span api, which has lifecycle commands that +could be used incorrectly. By only exposing scope, tag and log functionality, users can +collaborate without accidentally breaking span lifecycle.

  • collaboration with runtime generated code

    • with libraries such as Spring Data / Feign the implementations of interfaces are generated +at runtime thus span wrapping of objects was tedious. Now you can provide annotations + over interfaces and arguments of those interfaces

53.2 Creating new spans

If you really don’t want to take care of creating local spans manually you can profit from the +@NewSpan annotation. Also we give you the @SpanTag annotation to add tags in an automated +fashion.

Let’s look at some examples of usage.

@NewSpan
+void testMethod();

Annotating the method without any parameter will lead to a creation of a new span whose name +will be equal to annotated method name.

@NewSpan("customNameOnTestMethod4")
+void testMethod4();

If you provide the value in the annotation (either directly or via the name parameter) then +the created span will have the name as the provided value.

// method declaration
+@NewSpan(name = "customNameOnTestMethod5")
+void testMethod5(@SpanTag("testTag") String param);
+
+// and method execution
+this.testBean.testMethod5("test");

You can combine both the name and a tag. Let’s focus on the latter. In this case whatever the value of +the annotated method’s parameter runtime value will be - that will be the value of the tag. In our sample +the tag key will be testTag and the tag value will be test.

@NewSpan(name = "customNameOnTestMethod3")
+@Override
+public void testMethod3() {
+}

You can place the @NewSpan annotation on both the class and an interface. If you override the +interface’s method and provide a different value of the @NewSpan annotation then the most +concrete one wins (in this case customNameOnTestMethod3 will be set).

53.3 Continuing spans

If you want to just add tags and annotations to an existing span it’s enough +to use the @ContinueSpan annotation as presented below. Note that in contrast +with the @NewSpan annotation you can also add logs via the log parameter:

// method declaration
+@ContinueSpan(log = "testMethod11")
+void testMethod11(@SpanTag("testTag11") String param);
+
+// method execution
+this.testBean.testMethod11("test");

That way the span will get continued and:

  • logs with name testMethod11.before and testMethod11.after will be created
  • if an exception will be thrown a log testMethod11.afterFailure will also be created
  • tag with key testTag11 and value test will be created

53.4 More advanced tag setting

There are 3 different ways to add tags to a span. All of them are controlled by the SpanTag annotation. +Precedence is:

  • try with the bean of TagValueResolver type and provided name
  • if one hasn’t provided the bean name, try to evaluate an expression. We’re searching for a TagValueExpressionResolver bean. +The default implementation uses SPEL expression resolution. If we do not find any expression to evaluate, return the toString() +value of the parameter. +IMPORTANT You can only reference properties from the SPEL expression. Method execution is not allowed due to security constraints.
  • if one hasn’t provided any expression to evaluate just return a toString() value of the parameter

53.4.1 Custom extractor

The value of the tag for following method will be computed by an implementation of TagValueResolver interface. +Its class name has to be passed as the value of the resolver attribute.

Having such an annotated method:

@NewSpan
+public void getAnnotationForTagValueResolver(@SpanTag(key = "test", resolver = TagValueResolver.class) String test) {
+}

and such a TagValueResolver bean implementation

@Bean(name = "myCustomTagValueResolver")
+public TagValueResolver tagValueResolver() {
+	return parameter -> "Value from myCustomTagValueResolver";
+}

Will lead to setting of a tag value equal to Value from myCustomTagValueResolver.

53.4.2 Resolving expressions for value

Having such an annotated method:

@NewSpan
+public void getAnnotationForTagValueExpression(@SpanTag(key = "test", expression = "'hello' + ' characters'") String test) {
+}

and no custom implementation of a TagValueExpressionResolver will lead to evaluation of the SPEL expression and a tag with value 4 characters will be set on the span. +If you want to use some other expression resolution mechanism you can create your own implementation +of the bean.

53.4.3 Using toString method

Having such an annotated method:

@NewSpan
+public void getAnnotationForArgumentToString(@SpanTag("test") Long param) {
+}

if executed with a value of 15 will lead to setting of a tag with a String value of "15".

54. Customizations

Thanks to the SpanInjector and SpanExtractor you can customize the way spans +are created and propagated.

There are currently two built-in ways to pass tracing information between processes:

  • via Spring Integration
  • via HTTP

Span ids are extracted from Zipkin-compatible (B3) headers (either Message +or HTTP headers), to start or join an existing trace. Trace information is +injected into any outbound requests so the next hop can extract them.

The default way of coding tracing context is done via the b3 header that contains the +traceId-spanId-sampled notation (e.g. 0000000000000005-0000000000000004-1). +For backward compatibility, if the b3 header is not present, we also check if +X-B3 entries are present, and retrieve tracing context from there e.g. +(X-B3-TraceId: 0000000000000005, X-B3-SpanId: 0000000000000004, X-B3-Sampled: 1).

The key change in comparison to the previous versions of Sleuth is that Sleuth is implementing +the Open Tracing’s TextMap notion. In Sleuth it’s called SpanTextMap. Basically the idea +is that any means of communication (e.g. message, http request, etc.) can be abstracted via +a SpanTextMap. This abstraction defines how one can insert data into the carrier and +how to retrieve it from there. Thanks to this if you want to instrument a new HTTP library +that uses a FooRequest as a mean of sending HTTP requests then you have to create an +implementation of a SpanTextMap that delegates calls to FooRequest in terms of retrieval +and insertion of HTTP headers.

54.1 Spring Integration

For Spring Integration there are 2 interfaces responsible for creation of a Span from a Message. +These are:

  • MessagingSpanTextMapExtractor
  • MessagingSpanTextMapInjector

You can override them by providing your own implementation.

54.2 HTTP

For HTTP there are 2 interfaces responsible for creation of a Span from a Message. +These are:

  • HttpSpanExtractor
  • HttpSpanInjector

You can override them by providing your own implementation.

54.3 Example

Let’s assume that instead of the standard Zipkin compatible tracing HTTP header names +you have

  • for trace id - correlationId
  • for span id - mySpanId

This is a an example of a SpanExtractor

static class CustomHttpSpanExtractor implements HttpSpanExtractor {
+
+	@Override public Span joinTrace(SpanTextMap carrier) {
+		Map<String, String> map = TextMapUtil.asMap(carrier);
+		long traceId = Span.hexToId(map.get("correlationid"));
+		long spanId = Span.hexToId(map.get("myspanid"));
+		// extract all necessary headers
+		Span.SpanBuilder builder = Span.builder().traceId(traceId).spanId(spanId);
+		// build rest of the Span
+		return builder.build();
+	}
+}
+
+static class CustomHttpSpanInjector implements HttpSpanInjector {
+
+	@Override
+	public void inject(Span span, SpanTextMap carrier) {
+		carrier.put("correlationId", span.traceIdString());
+		carrier.put("mySpanId", Span.idToHex(span.getSpanId()));
+	}
+}

And you could register it like this:

@Bean
+HttpSpanInjector customHttpSpanInjector() {
+	return new CustomHttpSpanInjector();
+}
+
+@Bean
+HttpSpanExtractor customHttpSpanExtractor() {
+	return new CustomHttpSpanExtractor();
+}

Spring Cloud Sleuth does not add trace/span related headers to the Http Response for security reasons. If you need the headers then a custom SpanInjector +that injects the headers into the Http Response and a Servlet filter which makes use of this can be added the following way:

static class CustomHttpServletResponseSpanInjector extends ZipkinHttpSpanInjector {
+
+	@Override
+	public void inject(Span span, SpanTextMap carrier) {
+		super.inject(span, carrier);
+		carrier.put(Span.TRACE_ID_NAME, span.traceIdString());
+		carrier.put(Span.SPAN_ID_NAME, Span.idToHex(span.getSpanId()));
+	}
+}
+
+static class HttpResponseInjectingTraceFilter extends GenericFilterBean {
+
+	private final Tracer tracer;
+	private final HttpSpanInjector spanInjector;
+
+	public HttpResponseInjectingTraceFilter(Tracer tracer, HttpSpanInjector spanInjector) {
+		this.tracer = tracer;
+		this.spanInjector = spanInjector;
+	}
+
+	@Override
+	public void doFilter(ServletRequest request, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
+		HttpServletResponse response = (HttpServletResponse) servletResponse;
+		Span currentSpan = this.tracer.getCurrentSpan();
+		this.spanInjector.inject(currentSpan, new HttpServletResponseTextMap(response));
+		filterChain.doFilter(request, response);
+	}
+
+	 class HttpServletResponseTextMap implements SpanTextMap {
+
+		 private final HttpServletResponse delegate;
+
+		 HttpServletResponseTextMap(HttpServletResponse delegate) {
+			 this.delegate = delegate;
+		 }
+
+		 @Override
+		 public Iterator<Map.Entry<String, String>> iterator() {
+			 Map<String, String> map = new HashMap<>();
+			 for (String header : this.delegate.getHeaderNames()) {
+				map.put(header, this.delegate.getHeader(header));
+			 }
+			 return map.entrySet().iterator();
+		 }
+
+		 @Override
+		 public void put(String key, String value) {
+			this.delegate.addHeader(key, value);
+		 }
+	 }
+}

And you could register them like this:

@Bean HttpSpanInjector customHttpServletResponseSpanInjector() {
+	return new CustomHttpServletResponseSpanInjector();
+}
+
+@Bean
+HttpResponseInjectingTraceFilter responseInjectingTraceFilter(Tracer tracer) {
+	return new HttpResponseInjectingTraceFilter(tracer, customHttpServletResponseSpanInjector());
+}

54.4 TraceFilter

You can also modify the behaviour of the TraceFilter - the component that is responsible +for processing the input HTTP request and adding tags basing on the HTTP response. You can customize +the tags, or modify the response headers by registering your own instance of the TraceFilter bean.

In the following example we will register the TraceFilter bean and we will add the +ZIPKIN-TRACE-ID response header containing the current Span’s trace id. Also we will +add to the Span a tag with key custom and a value tag.

@Bean
+TraceFilter myTraceFilter(BeanFactory beanFactory, final Tracer tracer) {
+	return new TraceFilter(beanFactory) {
+		@Override protected void addResponseTags(HttpServletResponse response,
+				Throwable e) {
+			// execute the default behaviour
+			super.addResponseTags(response, e);
+			// for readability we're returning trace id in a hex form
+			response.addHeader("ZIPKIN-TRACE-ID",
+					Span.idToHex(tracer.getCurrentSpan().getTraceId()));
+			// we can also add some custom tags
+			tracer.addTag("custom", "tag");
+		}
+	};
+}

To change the order of TraceFilter registration, please set the +spring.sleuth.web.filter-order property.

54.5 Custom SA tag in Zipkin

Sometimes you want to create a manual Span that will wrap a call to an external service which is not instrumented. +What you can do is to create a span with the peer.service tag that will contain a value of the service that you want to call. +Below you can see an example of a call to Redis that is wrapped in such a span.

org.springframework.cloud.sleuth.Span newSpan = tracer.createSpan("redis");
+try {
+	newSpan.tag("redis.op", "get");
+	newSpan.tag("lc", "redis");
+	newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_SEND);
+	// call redis service e.g
+	// return (SomeObj) redisTemplate.opsForHash().get("MYHASH", someObjKey);
+} finally {
+	newSpan.tag("peer.service", "redisService");
+	newSpan.tag("peer.ipv4", "1.2.3.4");
+	newSpan.tag("peer.port", "1234");
+	newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_RECV);
+	tracer.close(newSpan);
+}
[Important]Important

Remember not to add both peer.service tag and the SA tag! You have to add only peer.service.

54.6 Custom service name

By default Sleuth assumes that when you send a span to Zipkin, you want the span’s service name + to be equal to spring.application.name value. That’s not always the case though. There + are situations in which you want to explicitly provide a different service name for all spans coming + from your application. To achieve that it’s enough to just pass the following property + to your application to override that value (example for foo service name):

spring.zipkin.service.name: foo

54.7 Customization of reported spans

Before reporting spans to e.g. Zipkin you can be interested in modifying that span in some way. + You can achieve that by using the SpanAdjuster interface.

Example of usage:

In Sleuth we’re generating spans with a fixed name. Some users want to modify the name depending on values +of tags. Implementation of the SpanAdjuster interface can be used to alter that name. Example:

@Bean
+SpanAdjuster customSpanAdjuster() {
+    return span -> span.toBuilder().name(scrub(span.getName())).build();
+}

This will lead in changing the name of the reported span just before it gets sent to Zipkin.

[Important]Important

Your SpanReporter should inject the SpanAdjuster and + allow span manipulation before the actual reporting is done.

54.8 Host locator

In order to define the host that is corresponding to a particular span we need to resolve the host name +and port. The default approach is to take it from server properties. If those for some reason are not set +then we’re trying to retrieve the host name from the network interfaces.

If you have the discovery client enabled and prefer to retrieve the host address from the registered +instance in a service registry then you have to set the property (it’s applicable for both HTTP and +Stream based span reporting).

spring.zipkin.locator.discovery.enabled: true

55. Sending spans to Zipkin

[Important]Important

spring-cloud-sleuth-stream is deprecated and should no longer be used. +If spring-cloud-sleuth-zipkin is on the classpath then the app will generate and collect Zipkin-compatible traces. +By default it sends them via HTTP to a Zipkin server on localhost (port 9411). If you depend +on spring-rabbit or spring-kafka your app will send traces to a broker instead of http.

By default if you add spring-cloud-starter-zipkin as a dependency to your project, +when the span is closed, it will be sent to Zipkin over HTTP. The communication +is asynchronous. You can configure the URL by setting the spring.zipkin.baseUrl +property as follows:

spring.zipkin.baseUrl: https://192.168.99.100:9411/

If you want to find Zipkin via service discovery it’s enough to pass the +Zipkin’s service id inside the URL. If you want to disable this feature +just set spring.zipkin.discoveryClientEnabled to false. +Example for `zipkinserver service id:

spring.zipkin.baseUrl: http://zipkinserver/

When this Discovery Client feature is enabled, Sleuth uses +LoadBalancerClient to find the URL of the Zipkin Server. It means +that you can set up the load balancing configuration e.g. via Ribbon.

zipkinserver:
+  ribbon:
+    ListOfServers: host1,host2

If you have web, rabbit or kafka together on the classpath, you might need +to pick the means by which you would like to send spans to zipkin. To do that +just set either web, rabbit or kafka to the spring.zipkin.sender.type property. +Example for web:

spring.zipkin.sender.type: web

To customize the RestTemplate that sends spans to Zipkin via HTTP, you can register +the ZipkinRestTemplateCustomizer bean.

@Configuration
+class MyConfig {
+	@Bean ZipkinRestTemplateCustomizer myCustomizer() {
+		return new ZipkinRestTemplateCustomizer() {
+			@Override
+			void customize(RestTemplate restTemplate) {
+				// customize the RestTemplate
+			}
+		};
+	}
+}

If, however, you would like to control the full process of creating the RestTemplate +object, you will have to create a bean of zipkin2.reporter.Sender type.

	@Bean Sender myRestTemplateSender(ZipkinProperties zipkin,
+			ZipkinRestTemplateCustomizer zipkinRestTemplateCustomizer) {
+		RestTemplate restTemplate = mySuperCustomRestTemplate();
+		zipkinRestTemplateCustomizer.customize(restTemplate);
+		return myCustomSender(zipkin, restTemplate);
+	}

56. Span Data as Messages

You can accumulate and send span data over +Spring Cloud Stream by +including the spring-cloud-sleuth-stream jar as a dependency, and +adding a Channel Binder implementation +(e.g. spring-cloud-starter-stream-rabbit for RabbitMQ or +spring-cloud-starter-stream-kafka for Kafka). This will +automatically turn your app into a producer of messages with payload +type Spans. The channel name to which the spans will be sent +is called sleuth.

56.1 Zipkin Consumer

[Important]Important

spring-cloud-sleuth-zipkin-stream is deprecated and should no longer be used. +Please use the OpenZipkin’s Zipkin server and set the environment variables +as presented here for rabbit (Zipkin 2.4.6) +or here for kafka (Zipkin 2.4.6)

There is a special convenience annotation for setting up a message consumer +for the Span data and pushing it into a Zipkin SpanStore. This application

@SpringBootApplication
+@EnableZipkinStreamServer
+public class Consumer {
+	public static void main(String[] args) {
+		SpringApplication.run(Consumer.class, args);
+	}
+}

will listen for the Span data on whatever transport you provide via a +Spring Cloud Stream Binder (e.g. include +spring-cloud-starter-stream-rabbit for RabbitMQ, and similar +starters exist for Redis and Kafka). If you add the following UI dependency

<groupId>io.zipkin.java</groupId>
+<artifactId>zipkin-autoconfigure-ui</artifactId>

Then you’ll have your app a +Zipkin server, which hosts +the UI and api on port 9411.

The default SpanStore is in-memory (good for demos and getting +started quickly). For a more robust solution you can add MySQL and +spring-boot-starter-jdbc to your classpath and enable the JDBC +SpanStore via configuration, e.g.:

spring:
+  rabbitmq:
+    host: ${RABBIT_HOST:localhost}
+  datasource:
+    schema: classpath:/mysql.sql
+    url: jdbc:mysql://${MYSQL_HOST:localhost}/test
+    username: root
+    password: root
+# Switch this on to create the schema on startup:
+    initialize: true
+    continueOnError: true
+  sleuth:
+    enabled: false
+zipkin:
+  storage:
+    type: mysql
[Note]Note

The @EnableZipkinStreamServer is also annotated with +@EnableZipkinServer so the process will also expose the standard +Zipkin server endpoints for collecting spans over HTTP, and for +querying in the Zipkin Web UI.

56.2 Custom Consumer

A custom consumer can also easily be implemented using +spring-cloud-sleuth-stream and binding to the SleuthSink. Example:

@EnableBinding(SleuthSink.class)
+@SpringBootApplication(exclude = SleuthStreamAutoConfiguration.class)
+@MessageEndpoint
+public class Consumer {
+
+    @ServiceActivator(inputChannel = SleuthSink.INPUT)
+    public void sink(Spans input) throws Exception {
+        // ... process spans
+    }
+}
[Note]Note

the sample consumer application above explicitly excludes +SleuthStreamAutoConfiguration so it doesn’t send messages to itself, +but this is optional (you might actually want to trace requests into +the consumer app).

In order to customize the polling mechanism you can create a bean of PollerMetadata type +with name equal to StreamSpanReporter.POLLER. Here you can find an example of such a configuration.

@Configuration
+public static class CustomPollerConfiguration {
+
+	@Bean(name = StreamSpanReporter.POLLER)
+	PollerMetadata customPoller() {
+		PollerMetadata poller = new PollerMetadata();
+		poller.setMaxMessagesPerPoll(500);
+		poller.setTrigger(new PeriodicTrigger(5000L));
+		return poller;
+	}
+}

57. Metrics

Currently Spring Cloud Sleuth registers very simple metrics related to spans. +It’s using the Spring Boot’s metrics support +to calculate the number of accepted and dropped spans. Each time a span gets +sent to Zipkin the number of accepted spans will increase. If there’s an error then +the number of dropped spans will get increased.

58. Integrations

58.1 Runnable and Callable

If you’re wrapping your logic in Runnable or Callable it’s enough to wrap those classes in their Sleuth representative.

Example for Runnable:

Runnable runnable = new Runnable() {
+	@Override
+	public void run() {
+		// do some work
+	}
+
+	@Override
+	public String toString() {
+		return "spanNameFromToStringMethod";
+	}
+};
+// Manual `TraceRunnable` creation with explicit "calculateTax" Span name
+Runnable traceRunnable = new TraceRunnable(tracer, spanNamer, runnable, "calculateTax");
+// Wrapping `Runnable` with `Tracer`. The Span name will be taken either from the
+// `@SpanName` annotation or from `toString` method
+Runnable traceRunnableFromTracer = tracer.wrap(runnable);

Example for Callable:

Callable<String> callable = new Callable<String>() {
+	@Override
+	public String call() throws Exception {
+		return someLogic();
+	}
+
+	@Override
+	public String toString() {
+		return "spanNameFromToStringMethod";
+	}
+};
+// Manual `TraceCallable` creation with explicit "calculateTax" Span name
+Callable<String> traceCallable = new TraceCallable<>(tracer, spanNamer, callable, "calculateTax");
+// Wrapping `Callable` with `Tracer`. The Span name will be taken either from the
+// `@SpanName` annotation or from `toString` method
+Callable<String> traceCallableFromTracer = tracer.wrap(callable);

That way you will ensure that a new Span is created and closed for each execution.

58.2 Hystrix

58.2.1 Custom Concurrency Strategy

We’re registering a custom HystrixConcurrencyStrategy +that wraps all Callable instances into their Sleuth representative - +the TraceCallable. The strategy either starts or continues a span depending on the fact whether tracing was already going +on before the Hystrix command was called. To disable the custom Hystrix Concurrency Strategy set the spring.sleuth.hystrix.strategy.enabled to false.

58.2.2 Manual Command setting

Assuming that you have the following HystrixCommand:

HystrixCommand<String> hystrixCommand = new HystrixCommand<String>(setter) {
+	@Override
+	protected String run() throws Exception {
+		return someLogic();
+	}
+};

In order to pass the tracing information you have to wrap the same logic in the Sleuth version of the HystrixCommand which is the +TraceCommand:

TraceCommand<String> traceCommand = new TraceCommand<String>(tracer, traceKeys, setter) {
+	@Override
+	public String doRun() throws Exception {
+		return someLogic();
+	}
+};

58.3 RxJava

We’re registering a custom RxJavaSchedulersHook +that wraps all Action0 instances into their Sleuth representative - +the TraceAction. The hook either starts or continues a span depending on the fact whether tracing was already going +on before the Action was scheduled. To disable the custom RxJavaSchedulersHook set the spring.sleuth.rxjava.schedulers.hook.enabled to false.

You can define a list of regular expressions for thread names, for which you don’t want a Span to be created. Just provide a comma separated list +of regular expressions in the spring.sleuth.rxjava.schedulers.ignoredthreads property.

58.4 HTTP integration

Features from this section can be disabled by providing the spring.sleuth.web.enabled property with value equal to false.

58.4.1 HTTP Filter

Via the TraceFilter all sampled incoming requests result in creation of a Span. That Span’s name is http: + the path to which + the request was sent. E.g. if the request was sent to /foo/bar then the name will be http:/foo/bar. You can configure which URIs you would + like to skip via the spring.sleuth.web.skipPattern property. If you have ManagementServerProperties on classpath then + its value of contextPath gets appended to the provided skip pattern.

58.4.2 HandlerInterceptor

Since we want the span names to be precise we’re using a TraceHandlerInterceptor that either wraps an + existing HandlerInterceptor or is added directly to the list of existing HandlerInterceptors. The + TraceHandlerInterceptor adds a special request attribute to the given HttpServletRequest. If the + the TraceFilter doesn’t see this attribute set it will create a "fallback" span which is an additional + span created on the server side so that the trace is presented properly in the UI. Seeing that most likely + signifies that there is a missing instrumentation. In that case please file an issue in Spring Cloud Sleuth.

58.4.3 Async Servlet support

If your controller returns a Callable or a WebAsyncTask Spring Cloud Sleuth will continue the existing span instead of creating a new one.

58.5 HTTP client integration

58.5.1 Synchronous Rest Template

We’re injecting a RestTemplate interceptor that ensures that all the tracing information is passed to the requests. Each time a +call is made a new Span is created. It gets closed upon receiving the response. In order to block the synchronous RestTemplate features +just set spring.sleuth.web.client.enabled to false.

[Important]Important

You have to register RestTemplate as a bean so that the interceptors will get injected. +If you create a RestTemplate instance with a new keyword then the instrumentation WILL NOT work.

58.5.2 Asynchronous Rest Template

[Important]Important

A traced version of an AsyncRestTemplate bean is registered for you out of the box. If you +have your own bean you have to wrap it in a TraceAsyncRestTemplate representation. The best solution +is to only customize the ClientHttpRequestFactory and / or AsyncClientHttpRequestFactory. +If you have your own AsyncRestTemplate and you don’t wrap it your calls WILL NOT GET TRACED.

Custom instrumentation is set to create and close Spans upon sending and receiving requests. You can customize the ClientHttpRequestFactory +and the AsyncClientHttpRequestFactory by registering your beans. Remember to use tracing compatible implementations (e.g. don’t forget to +wrap ThreadPoolTaskScheduler in a TraceAsyncListenableTaskExecutor). Example of custom request factories:

@EnableAutoConfiguration
+@Configuration
+public static class TestConfiguration {
+
+	@Bean
+	ClientHttpRequestFactory mySyncClientFactory() {
+		return new MySyncClientHttpRequestFactory();
+	}
+
+	@Bean
+	AsyncClientHttpRequestFactory myAsyncClientFactory() {
+		return new MyAsyncClientHttpRequestFactory();
+	}
+}

To block the AsyncRestTemplate features set spring.sleuth.web.async.client.enabled to false. +To disable creation of the default TraceAsyncClientHttpRequestFactoryWrapper set spring.sleuth.web.async.client.factory.enabled +to false. If you don’t want to create AsyncRestClient at all set spring.sleuth.web.async.client.template.enabled to false.

Multiple Asynchronous Rest Templates

Sometimes you need to use multiple implementations of Asynchronous Rest Template. In the following snippet you +can see an example of how to set up such a custom AsyncRestTemplate.

@Configuration
+@EnableAutoConfiguration
+static class Config {
+	@Autowired Tracer tracer;
+	@Autowired HttpTraceKeysInjector httpTraceKeysInjector;
+	@Autowired HttpSpanInjector spanInjector;
+
+	@Bean(name = "customAsyncRestTemplate")
+	public AsyncRestTemplate traceAsyncRestTemplate(@Qualifier("customHttpRequestFactoryWrapper")
+			TraceAsyncClientHttpRequestFactoryWrapper wrapper, ErrorParser errorParser) {
+		return new TraceAsyncRestTemplate(wrapper, this.tracer, errorParser);
+	}
+
+	@Bean(name = "customHttpRequestFactoryWrapper")
+	public TraceAsyncClientHttpRequestFactoryWrapper traceAsyncClientHttpRequestFactory() {
+		return new TraceAsyncClientHttpRequestFactoryWrapper(this.tracer,
+				this.spanInjector,
+				asyncClientFactory(),
+				clientHttpRequestFactory(),
+				this.httpTraceKeysInjector);
+	}
+
+	private ClientHttpRequestFactory clientHttpRequestFactory() {
+		ClientHttpRequestFactory clientHttpRequestFactory = new CustomClientHttpRequestFactory();
+		//CUSTOMIZE HERE
+		return clientHttpRequestFactory;
+	}
+
+	private AsyncClientHttpRequestFactory asyncClientFactory() {
+		AsyncClientHttpRequestFactory factory = new CustomAsyncClientHttpRequestFactory();
+		//CUSTOMIZE HERE
+		return factory;
+	}
+}

58.5.3 Traverson

If you’re using the Traverson library +it’s enough for you to inject a RestTemplate as a bean into your Traverson object. Since RestTemplate +is already intercepted, you will get full support of tracing in your client. Below you can find a pseudo code +of how to do that:

@Autowired RestTemplate restTemplate;
+
+Traverson traverson = new Traverson(URI.create("http://some/address"),
+    MediaType.APPLICATION_JSON, MediaType.APPLICATION_JSON_UTF8).setRestOperations(restTemplate);
+// use Traverson

58.6 Feign

By default Spring Cloud Sleuth provides integration with feign via the TraceFeignClientAutoConfiguration. You can disable it entirely +by setting spring.sleuth.feign.enabled to false. If you do so then no Feign related instrumentation will take place.

Part of Feign instrumentation is done via a FeignBeanPostProcessor. You can disable it by providing the spring.sleuth.feign.processor.enabled equal to false. +If you set it like this then Spring Cloud Sleuth will not instrument any of your custom Feign components. All the default instrumentation +however will be still there.

58.7 Asynchronous communication

58.7.1 @Async annotated methods

In Spring Cloud Sleuth we’re instrumenting async related components so that the tracing information is passed between threads. +You can disable this behaviour by setting the value of spring.sleuth.async.enabled to false.

If you annotate your method with @Async then we’ll automatically create a new Span with the following characteristics:

  • if the method is annotated with @SpanName then the value of the annotation will be the Span’s name
  • if the method is not annotated with @SpanName the Span name will be the annotated method name
  • the Span will be tagged with that method’s class name and the method name too

58.7.2 @Scheduled annotated methods

In Spring Cloud Sleuth we’re instrumenting scheduled method execution so that the tracing information is passed between threads. You can disable this behaviour +by setting the value of spring.sleuth.scheduled.enabled to false.

If you annotate your method with @Scheduled then we’ll automatically create a new Span with the following characteristics:

  • the Span name will be the annotated method name
  • the Span will be tagged with that method’s class name and the method name too

If you want to skip Span creation for some @Scheduled annotated classes you can set the +spring.sleuth.scheduled.skipPattern with a regular expression that will match the fully qualified name of the +@Scheduled annotated class.

[Tip]Tip

If you are using spring-cloud-sleuth-stream and spring-cloud-netflix-hystrix-stream together, Span will be created for each Hystrix metrics and sent to Zipkin. This may be annoying. You can prevent this by setting spring.sleuth.scheduled.skipPattern=org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask

58.7.3 Executor, ExecutorService and ScheduledExecutorService

We’re providing LazyTraceExecutor, TraceableExecutorService and TraceableScheduledExecutorService. Those implementations +are creating Spans each time a new task is submitted, invoked or scheduled.

Here you can see an example of how to pass tracing information with TraceableExecutorService when working with CompletableFuture:

CompletableFuture<Long> completableFuture = CompletableFuture.supplyAsync(() -> {
+	// perform some logic
+	return 1_000_000L;
+}, new TraceableExecutorService(executorService,
+		// 'calculateTax' explicitly names the span - this param is optional
+		tracer, traceKeys, spanNamer, "calculateTax"));
[Important]Important

Sleuth doesn’t work with parallelStream() out of the box. If you want +to have the tracing information propagated through the stream you have to use the +approach with supplyAsync(…​) as presented above.

Customization of Executors

Sometimes you need to set up a custom instance of the AsyncExecutor. In the following snippet you +can see an example of how to set up such a custom Executor.

@Configuration
+@EnableAutoConfiguration
+@EnableAsync
+static class CustomExecutorConfig extends AsyncConfigurerSupport {
+
+	@Autowired BeanFactory beanFactory;
+
+	@Override public Executor getAsyncExecutor() {
+		ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+		// CUSTOMIZE HERE
+		executor.setCorePoolSize(7);
+		executor.setMaxPoolSize(42);
+		executor.setQueueCapacity(11);
+		executor.setThreadNamePrefix("MyExecutor-");
+		// DON'T FORGET TO INITIALIZE
+		executor.initialize();
+		return new LazyTraceExecutor(this.beanFactory, executor);
+	}
+}

58.8 Messaging

Spring Cloud Sleuth integrates with Spring Integration. It creates spans for publish and +subscribe events. To disable Spring Integration instrumentation, set spring.sleuth.integration.enabled to false.

You can provide the spring.sleuth.integration.patterns pattern to explicitly +provide the names of channels that you want to include for tracing. By default all channels +are included.

[Important]Important

When using the Executor to build a Spring Integration IntegrationFlow remember to use the untraced version of the Executor. +Decorating Spring Integration Executor Channel with TraceableExecutorService will cause the spans to be improperly closed.

58.9 Zuul

We’re registering Zuul filters to propagate the tracing information (the request header is enriched with tracing data). +To disable Zuul support set the spring.sleuth.zuul.enabled property to false.

58.10 Spring Cloud Function

Sleuth works out of the box with Spring Cloud Function. Since functions +might be short living, it’s best to make the Zipkin span reporting synchronous. +Just define a Reporter<Span> bean as presented below:

@Configuration
+class ReporterConfiguration {
+	@Bean
+	public Reporter<Span> reporter(
+			SpanMetricReporter spanMetricReporter,
+			ZipkinProperties zipkin,
+			Sender sender
+	) {
+		final AsyncReporter<Span> reporter = AsyncReporter.builder(sender)
+				.queuedMaxSpans(1000)
+				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
+				.metrics(new ReporterMetricsAdapter(spanMetricReporter))
+				.build(zipkin.getEncoder());
+		return new Reporter<Span>() {
+			@Override public void report(Span span) {
+				reporter.report(span);
+				// make the reporter synchronous
+				reporter.flush();
+			}
+		};
+	}
+}

59. Running examples

You can find the running examples deployed in the Pivotal Web Services. Check them out in the following links:

Part VIII. Spring Cloud Consul

1.3.8.RELEASE

This project provides Consul integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with Consul based components. The +patterns provided include Service Discovery, Control Bus and Configuration. +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker +(Hystrix) are provided by integration with Spring Cloud Netflix.

60. Install Consul

Please see the installation documentation for instructions on how to install Consul.

61. Consul Agent

A Consul Agent client must be available to all Spring Cloud Consul applications. By default, the Agent client is expected to be at localhost:8500. See the Agent documentation for specifics on how to start an Agent client and how to connect to a cluster of Consul Agent Servers. For development, after you have installed consul, you may start a Consul Agent using the following command:

./src/main/bash/local_run_consul.sh

This will start an agent in server mode on port 8500, with the ui available at http://localhost:8500

62. Service Discovery with Consul

Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Consul provides Service Discovery services via an HTTP API and DNS. Spring Cloud Consul leverages the HTTP API for service registration and discovery. This does not prevent non-Spring Cloud applications from leveraging the DNS interface. Consul Agents servers are run in a cluster that communicates via a gossip protocol and uses the Raft consensus protocol.

62.1 How to activate

To activate Consul Service Discovery use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-discovery. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.

62.2 Registering with Consul

When a client registers with Consul, it provides meta-data about itself such as host and port, id, name and tags. An HTTP Check is created by default that Consul hits the /health endpoint every 10 seconds. If the health check fails, the service instance is marked as critical.

Example Consul client:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello world";
+    }
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

(i.e. utterly normal Spring Boot app). If the Consul client is located somewhere other than localhost:8500, the configuration is required to locate the client. Example:

application.yml.  +

spring:
+  cloud:
+    consul:
+      host: localhost
+      port: 8500

+

[Caution]Caution

If you use Spring Cloud Consul Config, the above values will need to be placed in bootstrap.yml instead of application.yml.

The default service name, instance id and port, taken from the Environment, are ${spring.application.name}, the Spring Context ID and ${server.port} respectively.

To disable the Consul Discovery Client you can set spring.cloud.consul.discovery.enabled to false.

To disable the service registration you can set spring.cloud.consul.discovery.register to false.

62.3 HTTP Health Check

The health check for a Consul instance defaults to "/health", which is the default locations of a useful endpoint in a Spring Boot Actuator application. You need to change these, even for an Actuator application if you use a non-default context path or servlet path (e.g. server.servletPath=/foo) or management endpoint path (e.g. management.context-path=/admin). The interval that Consul uses to check the health endpoint may also be configured. "10s" and "1m" represent 10 seconds and 1 minute respectively. Example:

application.yml.  +

spring:
+  cloud:
+    consul:
+      discovery:
+        healthCheckPath: ${management.context-path}/health
+        healthCheckInterval: 15s

+

62.3.1 Metadata and Consul tags

Consul does not yet support metadata on services. Spring Cloud’s ServiceInstance has a Map<String, String> metadata field. Spring Cloud Consul uses Consul tags to approximate metadata until Consul officially supports metadata. Tags with the form key=value will be split and used as a Map key and value respectively. Tags without the equal = sign, will be used as both the key and value.

application.yml.  +

spring:
+  cloud:
+    consul:
+      discovery:
+        tags: foo=bar, baz

+

The above configuration will result in a map with foo→bar and baz→baz.

62.3.2 Making the Consul Instance ID Unique

By default a consul instance is registered with an ID that is equal to its Spring Application Context ID. By default, the Spring Application Context ID is ${spring.application.name}:comma,separated,profiles:${server.port}. For most cases, this will allow multiple instances of one service to run on one machine. If further uniqueness is required, Using Spring Cloud you can override this by providing a unique identifier in spring.cloud.consul.discovery.instanceId. For example:

application.yml.  +

spring:
+  cloud:
+    consul:
+      discovery:
+        instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}

+

With this metadata, and multiple service instances deployed on localhost, the random value will kick in there to make the instance unique. In Cloudfoundry the vcap.application.instance_id will be populated automatically in a Spring Boot application, so the random value will not be needed.

62.4 Looking up services

62.4.1 Using Ribbon

Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate +for looking up services using the logical service names/ids instead of physical URLs. Both Feign and the discovery-aware RestTemplate utilize Ribbon for client-side load balancing.

If you want to access service STORES using the RestTemplate simply declare:

@LoadBalanced
+@Bean
+public RestTemplate loadbalancedRestTemplate() {
+     new RestTemplate();
+}

and use it like this (notice how we use the STORES service name/id from Consul instead of a fully qualified domainname):

@Autowired
+RestTemplate restTemplate;
+
+public String getFirstProduct() {
+   return this.restTemplate.getForObject("https://STORES/products/1", String.class);
+}

If you have Consul clusters in multiple datacenters and you want to access a service in another datacenter a service name/id alone is not enough. In that case +you use property spring.cloud.consul.discovery.datacenters.STORES=dc-west where STORES is the service name/id and dc-west is the datacenter +where the STORES service lives.

62.4.2 Using the DiscoveryClient

You can also use the org.springframework.cloud.client.discovery.DiscoveryClient which provides a simple API for discovery clients that is not specific to Netflix, e.g.

@Autowired
+private DiscoveryClient discoveryClient;
+
+public String serviceUrl() {
+    List<ServiceInstance> list = discoveryClient.getInstances("STORES");
+    if (list != null && list.size() > 0 ) {
+        return list.get(0).getUri();
+    }
+    return null;
+}

63. Distributed Configuration with Consul

Consul provides a Key/Value Store for storing configuration and other metadata. Spring Cloud Consul Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config folder by default. Multiple PropertySource instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created:

config/testApp,dev/
+config/testApp/
+config/application,dev/
+config/application/

The most specific property source is at the top, with the least specific at the bottom. Properties in the config/application folder are applicable to all applications using consul for configuration. Properties in the config/testApp folder are only available to the instances of the service named "testApp".

Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh will cause the configuration to be reloaded. Section 63.3, “Config Watch” will also automatically detect changes and reload the application context.

63.1 How to activate

To get started with Consul Configuration use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-config. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.

This will enable auto-configuration that will setup Spring Cloud Consul Config.

63.2 Customizing

Consul Config may be customized using the following properties:

bootstrap.yml.  +

spring:
+  cloud:
+    consul:
+      config:
+        enabled: true
+        prefix: configuration
+        defaultContext: apps
+        profileSeparator: '::'

+

  • enabled setting this value to "false" disables Consul Config
  • prefix sets the base folder for configuration values
  • defaultContext sets the folder name used by all applications
  • profileSeparator sets the value of the separator used to separate the profile name in property sources with profiles

63.3 Config Watch

The Consul Config Watch takes advantage of the ability of consul to watch a key prefix. The Config Watch makes a blocking Consul HTTP API call to determine if any relevant configuration data has changed for the current application. If there is new configuration data a Refresh Event is published. This is equivalent to calling the /refresh actuator endpoint.

To change the frequency of when the Config Watch is called change spring.cloud.consul.config.watch.delay. The default value is 1000, which is in milliseconds.

To disable the Config Watch set spring.cloud.consul.config.watch.enabled=false.

63.4 YAML or Properties with Config

It may be more convenient to store a blob of properties in YAML or Properties format as opposed to individual key/value pairs. Set the spring.cloud.consul.config.format property to YAML or PROPERTIES. For example to use YAML:

bootstrap.yml.  +

spring:
+  cloud:
+    consul:
+      config:
+        format: YAML

+

YAML must be set in the appropriate data key in consul. Using the defaults above the keys would look like:

config/testApp,dev/data
+config/testApp/data
+config/application,dev/data
+config/application/data

You could store a YAML document in any of the keys listed above.

You can change the data key using spring.cloud.consul.config.data-key.

63.5 git2consul with Config

git2consul is a Consul community project that loads files from a git repository to individual keys into Consul. By default the names of the keys are names of the files. YAML and Properties files are supported with file extensions of .yml and .properties respectively. Set the spring.cloud.consul.config.format property to FILES. For example:

bootstrap.yml.  +

spring:
+  cloud:
+    consul:
+      config:
+        format: FILES

+

Given the following keys in /config, the development profile and an application name of foo:

.gitignore
+application.yml
+bar.properties
+foo-development.properties
+foo-production.yml
+foo.properties
+master.ref

the following property sources would be created:

config/foo-development.properties
+config/foo.properties
+config/application.yml

The value of each key needs to be a properly formatted YAML or Properties file.

63.6 Fail Fast

It may be convenient in certain circumstances (like local development or certain test scenarios) to not fail if consul isn’t available for configuration. Setting spring.cloud.consul.config.failFast=false in bootstrap.yml will cause the configuration module to log a warning rather than throw an exception. This will allow the application to continue startup normally.

64. Consul Retry

If you expect that the consul agent may occasionally be unavailable when +your app starts, you can ask it to keep trying after a failure. You need to add +spring-retry and spring-boot-starter-aop to your classpath. The default +behaviour is to retry 6 times with an initial backoff interval of 1000ms and an +exponential multiplier of 1.1 for subsequent backoffs. You can configure these +properties (and others) using spring.cloud.consul.retry.* configuration properties. +This works with both Spring Cloud Consul Config and Discovery registration.

[Tip]Tip

To take full control of the retry add a @Bean of type +RetryOperationsInterceptor with id "consulRetryInterceptor". Spring +Retry has a RetryInterceptorBuilder that makes it easy to create one.

65. Spring Cloud Bus with Consul

65.1 How to activate

To get started with the Consul Bus use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-bus. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.

See the Spring Cloud Bus documentation for the available actuator endpoints and howto send custom messages.

66. Circuit Breaker with Hystrix

Applications can use the Hystrix Circuit Breaker provided by the Spring Cloud Netflix project by including this starter in the projects pom.xml: spring-cloud-starter-hystrix. Hystrix doesn’t depend on the Netflix Discovery Client. The @EnableHystrix annotation should be placed on a configuration class (usually the main class). Then methods can be annotated with @HystrixCommand to be protected by a circuit breaker. See the documentation for more details.

67. Hystrix metrics aggregation with Turbine and Consul

Turbine (provided by the Spring Cloud Netflix project), aggregates multiple instances Hystrix metrics streams, so the dashboard can display an aggregate view. Turbine uses the DiscoveryClient interface to lookup relevant instances. To use Turbine with Spring Cloud Consul, configure the Turbine application in a manner similar to the following examples:

pom.xml.  +

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-netflix-turbine</artifactId>
+</dependency>
+<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-starter-consul-discovery</artifactId>
+</dependency>

+

Notice that the Turbine dependency is not a starter. The turbine starter includes support for Netflix Eureka.

application.yml.  +

spring.application.name: turbine
+applications: consulhystrixclient
+turbine:
+  aggregator:
+    clusterConfig: ${applications}
+  appConfig: ${applications}

+

The clusterConfig and appConfig sections must match, so it’s useful to put the comma-separated list of service ID’s into a separate configuration property.

Turbine.java.  +

@EnableTurbine
+@SpringBootApplication
+public class Turbine {
+    public static void main(String[] args) {
+        SpringApplication.run(DemoturbinecommonsApplication.class, args);
+    }
+}

+

Part IX. Spring Cloud Zookeeper

This project provides Zookeeper integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with Zookeeper based components. The +patterns provided include Service Discovery and Configuration. +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker +(Hystrix) are provided by integration with Spring Cloud Netflix.

68. Install Zookeeper

Please see the installation documentation for instructions on how to install Zookeeper.

69. Service Discovery with Zookeeper

Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Curator(A java library for Zookeeper) provides Service Discovery services via Service Discovery Extension. Spring Cloud Zookeeper leverages this extension for service registration and discovery.

69.1 How to activate

Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery will enable auto-configuration that will setup Spring Cloud Zookeeper Discovery.

[Note]Note

You still need to include org.springframework.boot:spring-boot-starter-web for web functionality.

69.2 Registering with Zookeeper

When a client registers with Zookeeper, it provides meta-data about itself such as host and port, id and name.

Example Zookeeper client:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello world";
+    }
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(Application.class).web(true).run(args);
+    }
+
+}

(i.e. utterly normal Spring Boot app). If Zookeeper is located somewhere other than localhost:2181, the configuration is required to locate the server. Example:

application.yml.  +

spring:
+  cloud:
+    zookeeper:
+      connect-string: localhost:2181

+

[Caution]Caution

If you use Spring Cloud Zookeeper Config, the above values will need to be placed in bootstrap.yml instead of application.yml.

The default service name, instance id and port, taken from the Environment, are ${spring.application.name}, the Spring Context ID and ${server.port} respectively.

Having spring-cloud-starter-zookeeper-discovery on the classpath makes the app into both a Zookeeper "service" (i.e. it registers itself) and a "client" (i.e. it can query Zookeeper to locate other services).

If you would like to disable the Zookeeper Discovery Client you can set spring.cloud.zookeeper.discovery.enabled to false.

69.3 Using the DiscoveryClient

Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate using the logical service names instead of physical URLs.

You can also use the org.springframework.cloud.client.discovery.DiscoveryClient which provides a simple API for discovery clients that is not specific to Netflix, e.g.

@Autowired
+private DiscoveryClient discoveryClient;
+
+public String serviceUrl() {
+    List<ServiceInstance> list = discoveryClient.getInstances("STORES");
+    if (list != null && list.size() > 0 ) {
+        return list.get(0).getUri().toString();
+    }
+    return null;
+}

70. Using Spring Cloud Zookeeper with Spring Cloud Netflix Components

Spring Cloud Netflix supplies useful tools that work regardless of which DiscoveryClient implementation is used. Feign, Turbine, Ribbon and Zuul all work with Spring Cloud Zookeeper.

70.1 Ribbon with Zookeeper

Spring Cloud Zookeeper provides an implementation of Ribbon’s ServerList. When the spring-cloud-starter-zookeeper-discovery is used, Ribbon is auto-configured to use the ZookeeperServerList by default.

71. Spring Cloud Zookeeper and Service Registry

Spring Cloud Zookeeper implements the ServiceRegistry interface allowing developers to register arbitrary service in a programmatic way.

The ServiceInstanceRegistration class offers a builder() method to create a Registration object that can be used by the ServiceRegistry.

@Autowired
+private ZookeeperServiceRegistry serviceRegistry;
+
+public void registerThings() {
+    ZookeeperRegistration registration = ServiceInstanceRegistration.builder()
+            .defaultUriSpec()
+            .address("anyUrl")
+            .port(10)
+            .name("/a/b/c/d/anotherservice")
+            .build();
+    this.serviceRegistry.register(registration);
+}

71.1 Instance Status

Netflix Eureka supports having instances registered with the server that are OUT_OF_SERVICE and not returned as active service instances. This is very useful for behaviors such as blue/green deployments. The Curator Service Discovery recipe does not support this behavior. Taking advantage of the flexible payload has let Spring Cloud Zookeeper implement OUT_OF_SERVICE by updating some specific metadata and then filtering on that metadata in the Ribbon ZookeeperServerList. The ZookeeperServerList filters out all non-null instance statuses that do not equal UP. If the instance status field is empty, it is considered UP for backwards compatibility. To change the status of an instance POST OUT_OF_SERVICE to the ServiceRegistry instance status actuator endpoint.

----
+$ echo -n OUT_OF_SERVICE | http POST http://localhost:8081/service-registry/instance-status
+----
NOTE: The above example uses the `http` command from https://httpie.org

72. Zookeeper Dependencies

72.1 Using the Zookeeper Dependencies

Spring Cloud Zookeeper gives you a possibility to provide dependencies of your application as properties. As dependencies you can understand other applications that are registered +in Zookeeper and which you would like to call via Feign (a REST client builder) +and also Spring RestTemplate.

You can also benefit from the Zookeeper Dependency Watchers functionality that lets you control and monitor what is the state of your dependencies and decide what to do with that.

72.2 How to activate Zookeeper Dependencies

  • Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery will enable auto-configuration that will setup Spring Cloud Zookeeper Dependencies.
  • If you have to have the spring.cloud.zookeeper.dependencies section properly set up - check the subsequent section for more details then the feature is active
  • You can have the dependencies turned off even if you’ve provided the dependencies in your properties. Just set the property spring.cloud.zookeeper.dependency.enabled to false (defaults to true).

72.3 Setting up Zookeeper Dependencies

Let’s take a closer look at an example of dependencies representation:

application.yml.  +

spring.application.name: yourServiceName
+spring.cloud.zookeeper:
+  dependencies:
+    newsletter:
+      path: /path/where/newsletter/has/registered/in/zookeeper
+      loadBalancerType: ROUND_ROBIN
+      contentTypeTemplate: application/vnd.newsletter.$version+json
+      version: v1
+      headers:
+        header1:
+            - value1
+        header2:
+            - value2
+      required: false
+      stubs: org.springframework:foo:stubs
+    mailing:
+      path: /path/where/mailing/has/registered/in/zookeeper
+      loadBalancerType: ROUND_ROBIN
+      contentTypeTemplate: application/vnd.mailing.$version+json
+      version: v1
+      required: true

+

Let’s now go through each part of the dependency one by one. The root property name is spring.cloud.zookeeper.dependencies.

72.3.1 Aliases

Below the root property you have to represent each dependency has by an alias due to the constraints of Ribbon (the application id has to be placed in the URL +thus you can’t pass any complex path like /foo/bar/name). The alias will be the name that you will use instead of serviceId for DiscoveryClient, Feign or RestTemplate.

In the aforementioned examples the aliases are newsletter and mailing. Example of Feign usage with newsletter would be:

@FeignClient("newsletter")
+public interface NewsletterService {
+        @RequestMapping(method = RequestMethod.GET, value = "/newsletter")
+        String getNewsletters();
+}

72.3.2 Path

Represented by path yaml property.

Path is the path under which the dependency is registered under Zookeeper. Like presented before Ribbon operates on URLs thus this path is not compliant with its requirement. +That is why Spring Cloud Zookeeper maps the alias to the proper path.

72.3.3 Load balancer type

Represented by loadBalancerType yaml property.

If you know what kind of load balancing strategy has to be applied when calling this particular dependency then you can provide it in the yaml file and it will be automatically applied. +You can choose one of the following load balancing strategies

  • STICKY - once chosen the instance will always be called
  • RANDOM - picks an instance randomly
  • ROUND_ROBIN - iterates over instances over and over again

72.3.4 Content-Type template and version

Represented by contentTypeTemplate and version yaml property.

If you version your api via the Content-Type header then you don’t want to add this header to each of your requests. Also if you want to call a new version of the API you don’t want to +roam around your code to bump up the API version. That’s why you can provide a contentTypeTemplate with a special $version placeholder. That placeholder will be filled by the value of the +version yaml property. Let’s take a look at an example.

Having the following contentTypeTemplate:

application/vnd.newsletter.$version+json

and the following version:

v1

Will result in setting up of a Content-Type header for each request:

application/vnd.newsletter.v1+json

72.3.5 Default headers

Represented by headers map in yaml

Sometimes each call to a dependency requires setting up of some default headers. In order not to do that in code you can set them up in the yaml file. +Having the following headers section:

headers:
+    Accept:
+        - text/html
+        - application/xhtml+xml
+    Cache-Control:
+        - no-cache

Results in adding the Accept and Cache-Control headers with appropriate list of values in your HTTP request.

72.3.6 Obligatory dependencies

Represented by required property in yaml

If one of your dependencies is required to be up and running when your application is booting then it’s enough to set up the required: true property in the yaml file.

If your application can’t localize the required dependency during boot time it will throw an exception and the Spring Context will fail to set up. +In other words your application won’t be able to start if the required dependency is not registered in Zookeeper.

You can read more about Spring Cloud Zookeeper Presence Checker in the following sections.

72.3.7 Stubs

You can provide a colon separated path to the JAR containing stubs of the dependency. Example

stubs: org.springframework:foo:stubs

means that for a particular dependencies can be found under:

  • groupId: org.springframework
  • artifactId: foo
  • classifier: stubs - this is the default value

This is actually equal to

stubs: org.springframework:foo

since stubs is the default classifier.

72.4 Configuring Spring Cloud Zookeeper Dependencies

There is a bunch of properties that you can set to enable / disable parts of Zookeeper Dependencies functionalities.

  • spring.cloud.zookeeper.dependencies - if you don’t set this property you won’t benefit from Zookeeper Dependencies
  • spring.cloud.zookeeper.dependency.ribbon.enabled (enabled by default) - Ribbon requires explicit global configuration or a particular one for a dependency. By turning on this property +runtime load balancing strategy resolution is possible and you can profit from the loadBalancerType section of the Zookeeper Dependencies. The configuration that needs this property +has an implementation of LoadBalancerClient that delegates to the ILoadBalancer presented in the next bullet
  • spring.cloud.zookeeper.dependency.ribbon.loadbalancer (enabled by default) - thanks to this property the custom ILoadBalancer knows that the part of the URI passed to Ribbon might +actually be the alias that has to be resolved to a proper path in Zookeeper. Without this property you won’t be able to register applications under nested paths.
  • spring.cloud.zookeeper.dependency.headers.enabled (enabled by default) - this property registers such a RibbonClient that automatically will append appropriate headers and content +types with version as presented in the Dependency configuration. Without this setting of those two parameters will not be operational.
  • spring.cloud.zookeeper.dependency.resttemplate.enabled (enabled by default) - when enabled will modify the request headers of @LoadBalanced annotated RestTemplate so that it passes +headers and content type with version set in Dependency configuration. Wihtout this setting of those two parameters will not be operational.

73. Spring Cloud Zookeeper Dependency Watcher

The Dependency Watcher mechanism allows you to register listeners to your dependencies. The functionality is in fact an implementation of the Observator pattern. When a dependency changes +its state (UP or DOWN) then some custom logic can be applied.

73.1 How to activate

Spring Cloud Zookeeper Dependencies functionality needs to be enabled to profit from Dependency Watcher mechanism.

73.2 Registering a listener

In order to register a listener you have to implement an interface org.springframework.cloud.zookeeper.discovery.watcher.DependencyWatcherListener and register it as a bean. +The interface gives you one method:

    void stateChanged(String dependencyName, DependencyState newState);

If you want to register a listener for a particular dependency then the dependencyName would be the discriminator for your concrete implementation. newState will provide you with information + whether your dependency has changed to CONNECTED or DISCONNECTED.

73.3 Presence Checker

Bound with Dependency Watcher is the functionality called Presence Checker. It allows you to provide custom behaviour upon booting of your application to react accordingly to the state +of your dependencies.

The default implementation of the abstract org.springframework.cloud.zookeeper.discovery.watcher.presence.DependencyPresenceOnStartupVerifier class is the +org.springframework.cloud.zookeeper.discovery.watcher.presence.DefaultDependencyPresenceOnStartupVerifier which works in the following way.

  • If the dependency is marked us required and it’s not in Zookeeper then upon booting your application will throw an exception and shutdown
  • If dependency is not required the org.springframework.cloud.zookeeper.discovery.watcher.presence.LogMissingDependencyChecker will log that application is missing at WARN level

The functionality can be overriden since the DefaultDependencyPresenceOnStartupVerifier is registered only when there is no bean of DependencyPresenceOnStartupVerifier.

74. Distributed Configuration with Zookeeper

Zookeeper provides a hierarchical namespace that allows clients to store arbitrary data, such as configuration data. Spring Cloud Zookeeper Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config namespace by default. Multiple PropertySource instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created:

config/testApp,dev
+config/testApp
+config/application,dev
+config/application

The most specific property source is at the top, with the least specific at the bottom. Properties is the config/application namespace are applicable to all applications using zookeeper for configuration. Properties in the config/testApp namespace are only available to the instances of the service named "testApp".

Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh will cause the configuration to be reloaded. Watching the configuration namespace (which Zookeeper supports) is not currently implemented, but will be a future addition to this project.

74.1 How to activate

Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-config will enable auto-configuration that will setup Spring Cloud Zookeeper Config.

74.2 Customizing

Zookeeper Config may be customized using the following properties:

bootstrap.yml.  +

spring:
+  cloud:
+    zookeeper:
+      config:
+        enabled: true
+        root: configuration
+        defaultContext: apps
+        profileSeparator: '::'

+

  • enabled setting this value to "false" disables Zookeeper Config
  • root sets the base namespace for configuration values
  • defaultContext sets the name used by all applications
  • profileSeparator sets the value of the separator used to separate the profile name in property sources with profiles

74.3 ACLs

You can add authentication information for Zookeeper ACLs by calling the addAuthInfo method of a +CuratorFramework bean. One way to accomplish this is by providing your own CuratorFramework bean:

@BoostrapConfiguration
+public class CustomCuratorFrameworkConfig {
+
+  @Bean
+  public CuratorFramework curatorFramework() {
+    CuratorFramework curator = new CuratorFramework();
+    curator.addAuthInfo("digest", "user:password".getBytes());
+    return curator;
+  }
+
+}

Consult the ZookeeperAutoConfiguration class +to see how the CuratorFramework bean is configured by default.

Alternatively, you can add your credentials from a class that depends on the existing +CuratorFramework bean:

@BoostrapConfiguration
+public class DefaultCuratorFrameworkConfig {
+
+  public ZookeeperConfig(CuratorFramework curator) {
+    curator.addAuthInfo("digest", "user:password".getBytes());
+  }
+
+}

This must occur during the boostrapping phase. You can register configuration classes to run +during this phase by annotating them with @BootstrapConfiguration and including them in a +comma-separated list set as the value of the property +org.springframework.cloud.bootstrap.BootstrapConfiguration in the file +resources/META-INF/spring.factories:

resources/META-INF/spring.factories.  +

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
+my.project.CustomCuratorFrameworkConfig,\
+my.project.DefaultCuratorFrameworkConfig

+

Part X. Spring Boot Cloud CLI

Spring Boot CLI provides Spring +Boot command line features for Spring +Cloud. You can write Groovy scripts to run Spring Cloud component +applications (e.g. @EnableEurekaServer). You can also easily do +things like encryption and decryption to support Spring Cloud Config +clients with secret configuration values. With the Launcher CLI you +can launch services like Eureka, Zipkin, Config Server +conveniently all at once from the command line (very useful at +development time).

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

75. Installation

To install, make +sure you have +Spring Boot CLI +(1.5.2 or better):

$ spring version
+Spring CLI v1.5.4.RELEASE

E.g. for SDKMan users

$ sdk install springboot 1.5.4.RELEASE
+$ sdk use springboot 1.5.4.RELEASE

and install the Spring Cloud plugin

$ mvn install
+$ spring install org.springframework.cloud:spring-cloud-cli:1.4.0.BUILD-SNAPSHOT
[Important]Important

Prerequisites: to use the encryption and decryption features +you need the full-strength JCE installed in your JVM (it’s not there by default). +You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" +from Oracle, and follow instructions for installation (essentially replace the 2 policy files +in the JRE lib/security directory with the ones that you downloaded).

76. Running Spring Cloud Services in Development

The Launcher CLI can be used to run common services like Eureka, +Config Server etc. from the command line. To list the available +services you can do spring cloud --list, and to launch a default set +of services just spring cloud. To choose the services to deploy, +just list them on the command line, e.g.

$ spring cloud eureka configserver h2 kafka stubrunner zipkin

Summary of supported deployables:

ServiceNameAddressDescription

eureka

Eureka Server

http://localhost:8761

Eureka server for service registration and discovery. All the other services show up in its catalog by default.

configserver

Config Server

http://localhost:8888

Spring Cloud Config Server running in the "native" profile and serving configuration from the local directory ./launcher

h2

H2 Database

http://localhost:9095 (console), jdbc:h2:tcp://localhost:9096/{data}

Relation database service. Use a file path for {data} (e.g. ./target/test) when you connect. Remember that you can add ;MODE=MYSQL or ;MODE=POSTGRESQL to connect with compatibility to other server types.

kafka

Kafka Broker

http://localhost:9091 (actuator endpoints), localhost:9092

 

hystrixdashboard

Hystrix Dashboard

http://localhost:7979

Any Spring Cloud app that declares Hystrix circuit breakers publishes metrics on /hystrix.stream. Type that address into the dashboard to visualize all the metrics,

dataflow

Dataflow Server

http://localhost:9393

Spring Cloud Dataflow server with UI at /admin-ui. Connect the Dataflow shell to target at root path.

zipkin

Zipkin Server

http://localhost:9411

Zipkin Server with UI for visualizing traces. Stores span data in memory and accepts them via HTTP POST of JSON data.

stubrunner

Stub Runner Boot

http://localhost:8750

Downloads WireMock stubs, starts WireMock and feeds the started servers with stored stubs. Pass stubrunner.ids to pass stub coordinates and then go to http://localhost:8750/stubs.

Each of these apps can be configured using a local YAML file with the same name (in the current +working directory or a subdirectory called "config" or in ~/.spring-cloud). E.g. in configserver.yml you might want to +do something like this to locate a local git repository for the backend:

configserver.yml.  +

spring:
+  profiles:
+    active: git
+  cloud:
+    config:
+      server:
+        git:
+          uri: file://${user.home}/dev/demo/config-repo

+

E.g. in Stub Runner app you could fetch stubs from your local .m2 in the following way.

stubrunner.yml.  +

stubrunner:
+  workOffline: true
+  ids:
+    - com.example:beer-api-producer:+:9876

+

76.1 Adding Additional Applications

Additional applications can be added to ./config/cloud.yml (not +./config.yml because that would replace the defaults), e.g. with

config/cloud.yml.  +

spring:
+  cloud:
+    launcher:
+      deployables:
+        source:
+          coordinates: maven://com.example:source:0.0.1-SNAPSHOT
+          port: 7000
+        sink:
+          coordinates: maven://com.example:sink:0.0.1-SNAPSHOT
+          port: 7001

+

when you list the apps:

$ spring cloud --list
+source sink configserver dataflow eureka h2 hystrixdashboard kafka stubrunner zipkin

(notice the additional apps at the start of the list).

77. Writing Groovy Scripts and Running Applications

Spring Cloud CLI has support for most of the Spring Cloud declarative +features, such as the @Enable* class of annotations. For example, +here is a fully functional Eureka server

app.groovy.  +

@EnableEurekaServer
+class Eureka {}

+

which you can run from the command line like this

$ spring run app.groovy

To include additional dependencies, often it suffices just to add the +appropriate feature-enabling annotation, e.g. @EnableConfigServer, +@EnableOAuth2Sso or @EnableEurekaClient. To manually include a +dependency you can use a @Grab with the special "Spring Boot" short +style artifact co-ordinates, i.e. with just the artifact ID (no need +for group or version information), e.g. to set up a client app to +listen on AMQP for management events from the Spring CLoud Bus:

app.groovy.  +

@Grab('spring-cloud-starter-bus-amqp')
+@RestController
+class Service {
+  @RequestMapping('/')
+  def home() { [message: 'Hello'] }
+}

+

78. Encryption and Decryption

The Spring Cloud CLI comes with an "encrypt" and a "decrypt" +command. Both accept arguments in the same form with a key specified +as a mandatory "--key", e.g.

$ spring encrypt mysecret --key foo
+682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+$ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
+mysecret

To use a key in a file (e.g. an RSA public key for encyption) prepend +the key value with "@" and provide the file path, e.g.

$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub
+AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+...

Part XI. Spring Cloud Security

Spring Cloud Security offers a set of primitives for building secure +applications and services with minimum fuss. A declarative model which +can be heavily configured externally (or centrally) lends itself to +the implementation of large systems of co-operating, remote components, +usually with a central indentity management service. It is also extremely +easy to use in a service platform like Cloud Foundry. Building on +Spring Boot and Spring Security OAuth2 we can quickly create systems that +implement common patterns like single sign on, token relay and token +exchange.

[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

79. Quickstart

79.1 OAuth2 Single Sign On

Here’s a Spring Cloud "Hello World" app with HTTP Basic +authentication and a single user account:

app.groovy.  +

@Grab('spring-boot-starter-security')
+@Controller
+class Application {
+
+  @RequestMapping('/')
+  String home() {
+    'Hello World'
+  }
+
+}

+

You can run it with spring run app.groovy and watch the logs for the password (username is "user"). So far this is just the default for a Spring Boot app.

Here’s a Spring Cloud app with OAuth2 SSO:

app.groovy.  +

@Controller
+@EnableOAuth2Sso
+class Application {
+
+  @RequestMapping('/')
+  String home() {
+    'Hello World'
+  }
+
+}

+

Spot the difference? This app will actually behave exactly the same as +the previous one, because it doesn’t know it’s OAuth2 credentals +yet.

You can register an app in github quite easily, so try that if you +want a production app on your own domain. If you are happy to test on +localhost:8080, then set up these properties in your application +configuration:

application.yml.  +

security:
+  oauth2:
+    client:
+      clientId: bd1c0a783ccdd1c9b9e4
+      clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1
+      accessTokenUri: https://github.com/login/oauth/access_token
+      userAuthorizationUri: https://github.com/login/oauth/authorize
+      clientAuthenticationScheme: form
+    resource:
+      userInfoUri: https://api.github.com/user
+      preferTokenInfo: false

+

run the app above and it will redirect to github for authorization. If +you are already signed into github you won’t even notice that it has +authenticated. These credentials will only work if your app is +running on port 8080.

To limit the scope that the client asks for when it obtains an access token +you can set security.oauth2.client.scope (comma separated or an array in YAML). By +default the scope is empty and it is up to to Authorization Server to +decide what the defaults should be, usually depending on the settings in +the client registration that it holds.

[Note]Note

The examples above are all Groovy scripts. If you want to write the +same code in Java (or Groovy) you need to add Spring Security OAuth2 +to the classpath (e.g. see the +sample here).

79.2 OAuth2 Protected Resource

You want to protect an API resource with an OAuth2 token? Here’s a +simple example (paired with the client above):

app.groovy.  +

@Grab('spring-cloud-starter-security')
+@RestController
+@EnableResourceServer
+class Application {
+
+  @RequestMapping('/')
+  def home() {
+    [message: 'Hello World']
+  }
+
+}

+

and

application.yml.  +

security:
+  oauth2:
+    resource:
+      userInfoUri: https://api.github.com/user
+      preferTokenInfo: false

+

80. More Detail

80.1 Single Sign On

[Note]Note

All of the OAuth2 SSO and resource server features moved to Spring Boot +in version 1.3. You can find documentation in the +Spring Boot user guide.

80.2 Token Relay

A Token Relay is where an OAuth2 consumer acts as a Client and +forwards the incoming token to outgoing resource requests. The +consumer can be a pure Client (like an SSO application) or a Resource +Server.

80.2.1 Client Token Relay

If your app is a user facing OAuth2 client (i.e. has declared +@EnableOAuth2Sso or @EnableOAuth2Client) then it has an +OAuth2ClientContext in request scope from Spring Boot. You can +create your own OAuth2RestTemplate from this context and an +autowired OAuth2ProtectedResourceDetails, and then the context will +always forward the access token downstream, also refreshing the access +token automatically if it expires. (These are features of Spring +Security and Spring Boot.)

[Note]Note

Spring Boot (1.4.1) does not create an +OAuth2ProtectedResourceDetails automatically if you are using +client_credentials tokens. In that case you need to create your own +ClientCredentialsResourceDetails and configure it with +@ConfigurationProperties("security.oauth2.client").

80.2.2 Client Token Relay in Zuul Proxy

If your app also has a +Spring +Cloud Zuul embedded reverse proxy (using @EnableZuulProxy) then you +can ask it to forward OAuth2 access tokens downstream to the services +it is proxying. Thus the SSO app above can be enhanced simply like +this:

app.groovy.  +

@Controller
+@EnableOAuth2Sso
+@EnableZuulProxy
+class Application {
+
+}

+

and it will (in addition to logging the user in and grabbing a token) +pass the authentication token downstream to the /proxy/* +services. If those services are implemented with +@EnableResourceServer then they will get a valid token in the +correct header.

How does it work? The @EnableOAuth2Sso annotation pulls in +spring-cloud-starter-security (which you could do manually in a +traditional app), and that in turn triggers some autoconfiguration for +a ZuulFilter, which itself is activated because Zuul is on the +classpath (via @EnableZuulProxy). The +filter +just extracts an access token from the currently authenticated user, +and puts it in a request header for the downstream requests.

80.2.3 Resource Server Token Relay

If your app has @EnableResourceServer you might want to relay the +incoming token downstream to other services. If you use a +RestTemplate to contact the downstream services then this is just a +matter of how to create the template with the right context.

If your service uses UserInfoTokenServices to authenticate incoming +tokens (i.e. it is using the security.oauth2.user-info-uri +configuration), then you can simply create an OAuth2RestTemplate +using an autowired OAuth2ClientContext (it will be populated by the +authentication process before it hits the backend code). Equivalently +(with Spring Boot 1.4), you could inject a +UserInfoRestTemplateFactory and grab its OAuth2RestTemplate in +your configuration. For example:

MyConfiguration.java.  +

@Bean
+public OAuth2RestTemplate restTemplate(UserInfoRestTemplateFactory factory) {
+    return factory.getUserInfoRestTemplate();
+}

+

This rest template will then have the same OAuth2ClientContext +(request-scoped) that is used by the authentication filter, so you can +use it to send requests with the same access token.

If your app is not using UserInfoTokenServices but is still a client +(i.e. it declares @EnableOAuth2Client or @EnableOAuth2Sso), then +with Spring Security Cloud any OAuth2RestOperations that the user +creates from an @Autowired @OAuth2Context will also forward +tokens. This feature is implemented by default as an MVC handler +interceptor, so it only works in Spring MVC. If you are not using MVC +you could use a custom filter or AOP interceptor wrapping an +AccessTokenContextRelay to provide the same feature.

Here’s a basic +example showing the use of an autowired rest template created +elsewhere ("foo.com" is a Resource Server accepting the same tokens as +the surrounding app):

MyController.java.  +

@Autowired
+private OAuth2RestOperations restTemplate;
+
+@RequestMapping("/relay")
+public String relay() {
+    ResponseEntity<String> response =
+      restTemplate.getForEntity("https://foo.com/bar", String.class);
+    return "Success! (" + response.getBody() + ")";
+}

+

If you don’t want to forward tokens (and that is a valid +choice, since you might want to act as yourself, rather than the +client that sent you the token), then you only need to create your own +OAuth2Context instead of autowiring the default one.

Feign clients will also pick up an interceptor that uses the +OAuth2ClientContext if it is available, so they should also do a +token relay anywhere where a RestTemplate would.

81. Configuring Authentication Downstream of a Zuul Proxy

You can control the authorization behaviour downstream of an +@EnableZuulProxy through the proxy.auth.* settings. Example:

application.yml.  +

proxy:
+  auth:
+    routes:
+      customers: oauth2
+      stores: passthru
+      recommendations: none

+

In this example the "customers" service gets an OAuth2 token relay, +the "stores" service gets a passthrough (the authorization header is +just passed downstream), and the "recommendations" service has its +authorization header removed. The default behaviour is to do a token +relay if there is a token available, and passthru otherwise.

See + +ProxyAuthenticationProperties for full details.

Part XII. Spring Cloud for Cloud Foundry

Spring Cloud for Cloudfoundry makes it easy to run +Spring Cloud apps in +Cloud Foundry (the Platform as a +Service). Cloud Foundry has the notion of a "service", which is +middlware that you "bind" to an app, essentially providing it with an +environment variable containing credentials (e.g. the location and +username to use for the service).

The spring-cloud-cloudfoundry-web project provides basic support for +some enhanced features of webapps in Cloud Foundry: binding +automatically to single-sign-on services and optionally enabling +sticky routing for discovery.

The spring-cloud-cloudfoundry-discovery project provides an +implementation of Spring Cloud Commons DiscoveryClient so you can +@EnableDiscoveryClient and provide your credentials as +spring.cloud.cloudfoundry.discovery.[email,password] and then you +can use the DiscoveryClient directly or via a LoadBalancerClient +(also *.url if you are not connecting to +Pivotal Web Services).

The first time you use it the discovery client might be slow owing to +the fact that it has to get an access token from Cloud Foundry.

82. Discovery

Here’s a Spring Cloud app with Cloud Foundry discovery:

app.groovy.  +

@Grab('org.springframework.cloud:spring-cloud-cloudfoundry')
+@RestController
+@EnableDiscoveryClient
+class Application {
+
+  @Autowired
+  DiscoveryClient client
+
+  @RequestMapping('/')
+  String home() {
+    'Hello from ' + client.getLocalServiceInstance()
+  }
+
+}

+

If you run it without any service bindings:

$ spring jar app.jar app.groovy
+$ cf push -p app.jar

It will show its app name in the home page.

The DiscoveryClient can lists all the apps in a space, according to +the credentials it is authenticated with, where the space defaults to +the one the client is running in (if any). If neither org nor space +are configured, they default per the user’s profile in Cloud Foundry.

83. Single Sign On

[Note]Note

All of the OAuth2 SSO and resource server features moved to Spring Boot +in version 1.3. You can find documentation in the +Spring Boot user guide.

This project provides automatic binding from CloudFoundry service +credentials to the Spring Boot features. If you have a CloudFoundry +service called "sso", for instance, with credentials containing +"client_id", "client_secret" and "auth_domain", it will bind +automatically to the Spring OAuth2 client that you enable with +@EnableOAuth2Sso (from Spring Boot). The name of the service can be +parameterized using spring.oauth2.sso.serviceId.

Part XIII. Spring Cloud Contract

_Documentation Authors: Adam Dudczak, Mathias Düsterhöft, Marcin Grzejszczak, Dennis Kieselhorst, Jakub Kubryński, Karol Lassak, +Olga Maciaszek-Sharma, Mariusz Smykuła, Dave Syer, Jay Bryant

1.3.8.RELEASE

84. Spring Cloud Contract

You need confidence when pushing new features to a new application or service in a +distributed system. This project provides support for Consumer Driven Contracts and +service schemas in Spring applications (for both HTTP and message-based interactions), +covering a range of options for writing tests, publishing them as assets, and asserting +that a contract is kept by producers and consumers.

85. Spring Cloud Contract Verifier Introduction

[Tip]Tip

The Accurest project was initially started by Marcin Grzejszczak and Jakub Kubrynski +(Codearte)

Spring Cloud Contract Verifier enables Consumer Driven Contract (CDC) development of +JVM-based applications. It moves TDD to the level of software architecture.

Spring Cloud Contract Verifier ships with Contract Definition Language (CDL). Contract +definitions are used to produce the following resources:

  • JSON stub definitions to be used by WireMock when doing integration testing on the +client code (client tests). Test code must still be written by hand, and test data is +produced by Spring Cloud Contract Verifier.
  • Messaging routes, if you’re using a messaging service. We integrate with Spring +Integration, Spring Cloud Stream, Spring AMQP, and Apache Camel. You can also set your +own integrations.
  • Acceptance tests (in JUnit or Spock) are used to verify if server-side implementation +of the API is compliant with the contract (server tests). A full test is generated by +Spring Cloud Contract Verifier.

85.1 Why a Contract Verifier?

Assume that we have a system consisting of multiple microservices:

Microservices Architecture

85.1.1 Testing issues

If we wanted to test the application in top left corner to determine whether it can +communicate with other services, we could do one of two things:

  • Deploy all microservices and perform end-to-end tests.
  • Mock other microservices in unit/integration tests.

Both have their advantages but also a lot of disadvantages.

Deploy all microservices and perform end to end tests

Advantages:

  • Simulates production.
  • Tests real communication between services.

Disadvantages:

  • To test one microservice, we have to deploy 6 microservices, a couple of databases, +etc.
  • The environment where the tests run is locked for a single suite of tests (nobody else +would be able to run the tests in the meantime).
  • They take a long time to run.
  • The feedback comes very late in the process.
  • They are extremely hard to debug.

Mock other microservices in unit/integration tests

Advantages:

  • They provide very fast feedback.
  • They have no infrastructure requirements.

Disadvantages:

  • The implementor of the service creates stubs that might have nothing to do with +reality.
  • You can go to production with passing tests and failing production.

To solve the aforementioned issues, Spring Cloud Contract Verifier with Stub Runner was +created. The main idea is to give you very fast feedback, without the need to set up the +whole world of microservices. If you work on stubs, then the only applications you need +are those that your application directly uses.

Stubbed Services

Spring Cloud Contract Verifier gives you the certainty that the stubs that you use were +created by the service that you’re calling. Also, if you can use them, it means that they +were tested against the producer’s side. In short, you can trust those stubs.

85.2 Purposes

The main purposes of Spring Cloud Contract Verifier with Stub Runner are:

  • To ensure that WireMock/Messaging stubs (used when developing the client) do exactly +what the actual server-side implementation does.
  • To promote ATDD method and Microservices architectural style.
  • To provide a way to publish changes in contracts that are immediately visible on both +sides.
  • To generate boilerplate test code to be used on the server side.
[Important]Important

Spring Cloud Contract Verifier’s purpose is NOT to start writing business +features in the contracts. Assume that we have a business use case of fraud check. If a +user can be a fraud for 100 different reasons, we would assume that you would create 2 +contracts, one for the positive case and one for the negative case. Contract tests are +used to test contracts between applications and not to simulate full behavior.

85.3 How It Works

This section explores how Spring Cloud Contract Verifier with Stub Runner works.

85.3.1 Defining the contract

As consumers of services, we need to define what exactly we want to achieve. We need to +formulate our expectations. That is why we write contracts.

Assume that you want to send a request containing the ID of a client company and the +amount it wants to borrow from us. You also want to send it to the /fraudcheck url via +the PUT method.

Groovy DSL.  +

package contracts
+
+org.springframework.cloud.contract.spec.Contract.make {
+	request { // (1)
+		method 'PUT' // (2)
+		url '/fraudcheck' // (3)
+		body([ // (4)
+			   "client.id": $(regex('[0-9]{10}')),
+			   loanAmount: 99999
+		])
+		headers { // (5)
+			contentType('application/json')
+		}
+	}
+	response { // (6)
+		status 200 // (7)
+		body([ // (8)
+			   fraudCheckStatus: "FRAUD",
+			   "rejection.reason": "Amount too high"
+		])
+		headers { // (9)
+			contentType('application/json')
+		}
+	}
+}
+
+/*
+From the Consumer perspective, when shooting a request in the integration test:
+
+(1) - If the consumer sends a request
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the response will be sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` equal to `application/json`
+
+From the Producer perspective, in the autogenerated producer-side test:
+
+(1) - A request will be sent to the producer
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that will have a generated value that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the test will assert if the response has been sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` matching `application/json.*`
+ */

+

YAML.  +

request: # (1)
+  method: PUT # (2)
+  url: /fraudcheck # (3)
+  body: # (4)
+    "client.id": 1234567890
+    loanAmount: 99999
+  headers: # (5)
+    Content-Type: application/json
+  matchers:
+    body:
+      - path: $.['client.id'] # (6)
+        type: by_regex
+        value: "[0-9]{10}"
+response: # (7)
+  status: 200 # (8)
+  body:  # (9)
+    fraudCheckStatus: "FRAUD"
+    "rejection.reason": "Amount too high"
+  headers: # (10)
+    Content-Type: application/json;charset=UTF-8
+
+
+#From the Consumer perspective, when shooting a request in the integration test:
+#
+#(1) - If the consumer sends a request
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}`
+#(7) - then the response will be sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json`
+#
+#From the Producer perspective, in the autogenerated producer-side test:
+#
+#(1) - A request will be sent to the producer
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id` `1234567890`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(7) - then the test will assert if the response has been sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8`

+

85.3.2 Client Side

Spring Cloud Contract generates stubs, which you can use during client-side testing. +You get a running WireMock instance/Messaging route that simulates the service. +You would like to feed that instance with a proper stub definition.

At some point in time, you need to send a request to the Fraud Detection service.

ResponseEntity<FraudServiceResponse> response =
+		restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
+				new HttpEntity<>(request, httpHeaders),
+				FraudServiceResponse.class);

Annotate your test class with @AutoConfigureStubRunner. In the annotation provide the group id and artifact id for the Stub Runner to download stubs of your collaborators.

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment=WebEnvironment.NONE)
+@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
+public class LoanApplicationServiceTests {

After that, during the tests, Spring Cloud Contract automatically finds the stubs +(simulating the real service) in the Maven repository and exposes them on a configured +(or random) port.

85.3.3 Server Side

Since you are developing your stub, you need to be sure that it actually resembles your +concrete implementation. You cannot have a situation where your stub acts in one way and +your application behaves in a different way, especially in production.

To ensure that your application behaves the way you define in your stub, tests are +generated from the stub you provide.

The autogenerated test looks, more or less, like this:

@Test
+public void validate_shouldMarkClientAsFraud() throws Exception {
+    // given:
+        MockMvcRequestSpecification request = given()
+                .header("Content-Type", "application/vnd.fraud.v1+json")
+                .body("{\"client.id\":\"1234567890\",\"loanAmount\":99999}");
+
+    // when:
+        ResponseOptions response = given().spec(request)
+                .put("/fraudcheck");
+
+    // then:
+        assertThat(response.statusCode()).isEqualTo(200);
+        assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*");
+    // and:
+        DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+        assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}");
+        assertThatJson(parsedJson).field("['rejection.reason']").isEqualTo("Amount too high");
+}

85.4 Step-by-step Guide to Consumer Driven Contracts (CDC)

Consider an example of Fraud Detection and the Loan Issuance process. The business +scenario is such that we want to issue loans to people but do not want them to steal from +us. The current implementation of our system grants loans to everybody.

Assume that Loan Issuance is a client to the Fraud Detection server. In the current +sprint, we must develop a new feature: if a client wants to borrow too much money, then +we mark the client as a fraud.

Technical remark - Fraud Detection has an artifact-id of http-server, while Loan +Issuance has an artifact-id of http-client, and both have a group-id of com.example.

Social remark - both client and server development teams need to communicate directly and +discuss changes while going through the process. CDC is all about communication.

The server +side code is available here and the +client code here.

[Tip]Tip

In this case, the producer owns the contracts. Physically, all the contract are +in the producer’s repository.

85.4.1 Technical note

If using the SNAPSHOT / Milestone / Release Candidate versions please add the +following section to your build:

Maven.  +

<repositories>
+	<repository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+</repositories>
+<pluginRepositories>
+	<pluginRepository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+</pluginRepositories>

+

Gradle.  +

repositories {
+	mavenCentral()
+	mavenLocal()
+	maven { url "https://repo.spring.io/snapshot" }
+	maven { url "https://repo.spring.io/milestone" }
+	maven { url "https://repo.spring.io/release" }
+}

+

85.4.2 Consumer side (Loan Issuance)

As a developer of the Loan Issuance service (a consumer of the Fraud Detection server), you might do the following steps:

  1. Start doing TDD by writing a test for your feature.
  2. Write the missing implementation.
  3. Clone the Fraud Detection service repository locally.
  4. Define the contract locally in the repo of Fraud Detection service.
  5. Add the Spring Cloud Contract Verifier plugin.
  6. Run the integration tests.
  7. File a pull request.
  8. Create an initial implementation.
  9. Take over the pull request.
  10. Write the missing implementation.
  11. Deploy your app.
  12. Work online.

Start doing TDD by writing a test for your feature.

@Test
+public void shouldBeRejectedDueToAbnormalLoanAmount() {
+	// given:
+	LoanApplication application = new LoanApplication(new Client("1234567890"),
+			99999);
+	// when:
+	LoanApplicationResult loanApplication = service.loanApplication(application);
+	// then:
+	assertThat(loanApplication.getLoanApplicationStatus())
+			.isEqualTo(LoanApplicationStatus.LOAN_APPLICATION_REJECTED);
+	assertThat(loanApplication.getRejectionReason()).isEqualTo("Amount too high");
+}

Assume that you have written a test of your new feature. If a loan application for a big +amount is received, the system should reject that loan application with some description.

Write the missing implementation.

At some point in time, you need to send a request to the Fraud Detection service. Assume +that you need to send the request containing the ID of the client and the amount the +client wants to borrow. You want to send it to the /fraudcheck url via the PUT method.

ResponseEntity<FraudServiceResponse> response =
+		restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
+				new HttpEntity<>(request, httpHeaders),
+				FraudServiceResponse.class);

For simplicity, the port of the Fraud Detection service is set to 8080, and the +application runs on 8090.

If you start the test at this point, it breaks, because no service currently runs on port +8080.

Clone the Fraud Detection service repository locally.

You can start by playing around with the server side contract. To do so, you must first +clone it.

$ git clone https://your-git-server.com/server-side.git local-http-server-repo

Define the contract locally in the repo of Fraud Detection service.

As a consumer, you need to define what exactly you want to achieve. You need to formulate +your expectations. To do so, write the following contract:

[Important]Important

Place the contract under src/test/resources/contracts/fraud folder. The fraud folder +is important because the producer’s test base class name references that folder.

Groovy DSL.  +

package contracts
+
+org.springframework.cloud.contract.spec.Contract.make {
+	request { // (1)
+		method 'PUT' // (2)
+		url '/fraudcheck' // (3)
+		body([ // (4)
+			   "client.id": $(regex('[0-9]{10}')),
+			   loanAmount: 99999
+		])
+		headers { // (5)
+			contentType('application/json')
+		}
+	}
+	response { // (6)
+		status 200 // (7)
+		body([ // (8)
+			   fraudCheckStatus: "FRAUD",
+			   "rejection.reason": "Amount too high"
+		])
+		headers { // (9)
+			contentType('application/json')
+		}
+	}
+}
+
+/*
+From the Consumer perspective, when shooting a request in the integration test:
+
+(1) - If the consumer sends a request
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the response will be sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` equal to `application/json`
+
+From the Producer perspective, in the autogenerated producer-side test:
+
+(1) - A request will be sent to the producer
+(2) - With the "PUT" method
+(3) - to the URL "/fraudcheck"
+(4) - with the JSON body that
+ * has a field `client.id` that will have a generated value that matches a regular expression `[0-9]{10}`
+ * has a field `loanAmount` that is equal to `99999`
+(5) - with header `Content-Type` equal to `application/json`
+(6) - then the test will assert if the response has been sent with
+(7) - status equal `200`
+(8) - and JSON body equal to
+ { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+(9) - with header `Content-Type` matching `application/json.*`
+ */

+

YAML.  +

request: # (1)
+  method: PUT # (2)
+  url: /fraudcheck # (3)
+  body: # (4)
+    "client.id": 1234567890
+    loanAmount: 99999
+  headers: # (5)
+    Content-Type: application/json
+  matchers:
+    body:
+      - path: $.['client.id'] # (6)
+        type: by_regex
+        value: "[0-9]{10}"
+response: # (7)
+  status: 200 # (8)
+  body:  # (9)
+    fraudCheckStatus: "FRAUD"
+    "rejection.reason": "Amount too high"
+  headers: # (10)
+    Content-Type: application/json;charset=UTF-8
+
+
+#From the Consumer perspective, when shooting a request in the integration test:
+#
+#(1) - If the consumer sends a request
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}`
+#(7) - then the response will be sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json`
+#
+#From the Producer perspective, in the autogenerated producer-side test:
+#
+#(1) - A request will be sent to the producer
+#(2) - With the "PUT" method
+#(3) - to the URL "/fraudcheck"
+#(4) - with the JSON body that
+# * has a field `client.id` `1234567890`
+# * has a field `loanAmount` that is equal to `99999`
+#(5) - with header `Content-Type` equal to `application/json`
+#(7) - then the test will assert if the response has been sent with
+#(8) - status equal `200`
+#(9) - and JSON body equal to
+# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
+#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8`

+

The YML contract is quite straight-forward. However when you take a look at the Contract +written using a statically typed Groovy DSL - you might wonder what the +value(client(…​), server(…​)) parts are. By using this notation, Spring Cloud +Contract lets you define parts of a JSON block, a URL, etc., which are dynamic. In case +of an identifier or a timestamp, you need not hardcode a value. You want to allow some +different ranges of values. To enable ranges of values, you can set regular expressions +matching those values for the consumer side. You can provide the body by means of either +a map notation or String with interpolations. +Consult the docs +for more information. We highly recommend using the map notation!

[Tip]Tip

You must understand the map notation in order to set up contracts. Please read the +Groovy docs regarding JSON.

The previously shown contract is an agreement between two sides that:

  • if an HTTP request is sent with all of

    • a PUT method on the /fraudcheck endpoint,
    • a JSON body with a client.id that matches the regular expression [0-9]{10} and +loanAmount equal to 99999,
    • and a Content-Type header with a value of application/vnd.fraud.v1+json,

  • then an HTTP response is sent to the consumer that

    • has status 200,
    • contains a JSON body with the fraudCheckStatus field containing a value FRAUD and +the rejectionReason field having value Amount too high,
    • and a Content-Type header with a value of application/vnd.fraud.v1+json.

Once you are ready to check the API in practice in the integration tests, you need to +install the stubs locally.

Add the Spring Cloud Contract Verifier plugin.

We can add either a Maven or a Gradle plugin. In this example, you see how to add Maven. +First, add the Spring Cloud Contract BOM.

<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>${spring-cloud-dependencies.version}</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

Next, add the Spring Cloud Contract Verifier Maven plugin

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+</plugin>

Since the plugin was added, you get the Spring Cloud Contract Verifier features which, +from the provided contracts:

  • generate and run tests
  • produce and install stubs

You do not want to generate tests since you, as the consumer, want only to play with the +stubs. You need to skip the test generation and execution. When you execute:

$ cd local-http-server-repo
+$ ./mvnw clean install -DskipTests

In the logs, you see something like this:

[INFO] --- spring-cloud-contract-maven-plugin:1.0.0.BUILD-SNAPSHOT:generateStubs (default-generateStubs) @ http-server ---
+[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar
+[INFO]
+[INFO] --- maven-jar-plugin:2.6:jar (default-jar) @ http-server ---
+[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar
+[INFO]
+[INFO] --- spring-boot-maven-plugin:1.5.5.BUILD-SNAPSHOT:repackage (default) @ http-server ---
+[INFO]
+[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ http-server ---
+[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.jar
+[INFO] Installing /some/path/http-server/pom.xml to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.pom
+[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar

The following line is extremely important:

[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar

It confirms that the stubs of the http-server have been installed in the local +repository.

Run the integration tests.

In order to profit from the Spring Cloud Contract Stub Runner functionality of automatic +stub downloading, you must do the following in your consumer side project (Loan +Application service):

Add the Spring Cloud Contract BOM:

<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>${spring-cloud-dependencies.version}</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

Add the dependency to Spring Cloud Contract Stub Runner:

<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
+	<scope>test</scope>
+</dependency>

Annotate your test class with @AutoConfigureStubRunner. In the annotation, provide the +group-id and artifact-id for the Stub Runner to download the stubs of your +collaborators. (Optional step) Because you’re playing with the collaborators offline, you +can also provide the offline work switch.

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment=WebEnvironment.NONE)
+@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
+public class LoanApplicationServiceTests {

Now, when you run your tests, you see something like this:

2016-07-19 14:22:25.403  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Desired version is + - will try to resolve the latest version
+2016-07-19 14:22:25.438  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Resolved version is 0.0.1-SNAPSHOT
+2016-07-19 14:22:25.439  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Resolving artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT using remote repositories []
+2016-07-19 14:22:25.451  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Resolved artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar
+2016-07-19 14:22:25.465  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Unpacking stub from JAR [URI: file:/path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar]
+2016-07-19 14:22:25.475  INFO 41050 --- [           main] o.s.c.c.stubrunner.AetherStubDownloader  : Unpacked file to [/var/folders/0p/xwq47sq106x1_g3dtv6qfm940000gq/T/contracts100276532569594265]
+2016-07-19 14:22:27.737  INFO 41050 --- [           main] o.s.c.c.stubrunner.StubRunnerExecutor    : All stubs are now running RunningStubs [namesAndPorts={com.example:http-server:0.0.1-SNAPSHOT:stubs=8080}]

This output means that Stub Runner has found your stubs and started a server for your app +with group id com.example, artifact id http-server with version 0.0.1-SNAPSHOT of +the stubs and with stubs classifier on port 8080.

File a pull request.

What you have done until now is an iterative process. You can play around with the +contract, install it locally, and work on the consumer side until the contract works as +you wish.

Once you are satisfied with the results and the test passes, publish a pull request to +the server side. Currently, the consumer side work is done.

85.4.3 Producer side (Fraud Detection server)

As a developer of the Fraud Detection server (a server to the Loan Issuance service):

Create an initial implementation.

As a reminder, you can see the initial implementation here:

@RequestMapping(value = "/fraudcheck", method = PUT)
+public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
+return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
+}

Take over the pull request.

$ git checkout -b contract-change-pr master
+$ git pull https://your-git-server.com/server-side-fork.git contract-change-pr

You must add the dependencies needed by the autogenerated tests:

<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-starter-contract-verifier</artifactId>
+	<scope>test</scope>
+</dependency>

In the configuration of the Maven plugin, pass the packageWithBaseClasses property

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+</plugin>
[Important]Important

This example uses "convention based" naming by setting the +packageWithBaseClasses property. Doing so means that the two last packages combine to +make the name of the base test class. In our case, the contracts were placed under +src/test/resources/contracts/fraud. Since you do not have two packages starting from +the contracts folder, pick only one, which should be fraud. Add the Base suffix and +capitalize fraud. That gives you the FraudBase test class name.

All the generated tests extend that class. Over there, you can set up your Spring Context +or whatever is necessary. In this case, use Rest Assured MVC to +start the server side FraudDetectionController.

package com.example.fraud;
+
+import org.junit.Before;
+
+import io.restassured.module.mockmvc.RestAssuredMockMvc;
+
+public class FraudBase {
+	@Before
+	public void setup() {
+		RestAssuredMockMvc.standaloneSetup(new FraudDetectionController(),
+				new FraudStatsController(stubbedStatsProvider()));
+	}
+
+	private StatsProvider stubbedStatsProvider() {
+		return fraudType -> {
+			switch (fraudType) {
+			case DRUNKS:
+				return 100;
+			case ALL:
+				return 200;
+			}
+			return 0;
+		};
+	}
+
+	public void assertThatRejectionReasonIsNull(Object rejectionReason) {
+		assert rejectionReason == null;
+	}
+}

Now, if you run the ./mvnw clean install, you get something like this:

Results :
+
+Tests in error:
+  ContractVerifierTest.validate_shouldMarkClientAsFraud:32 » IllegalState Parsed...

This error occurs because you have a new contract from which a test was generated and it +failed since you have not implemented the feature. The auto-generated test would look +like this:

@Test
+public void validate_shouldMarkClientAsFraud() throws Exception {
+    // given:
+        MockMvcRequestSpecification request = given()
+                .header("Content-Type", "application/vnd.fraud.v1+json")
+                .body("{\"client.id\":\"1234567890\",\"loanAmount\":99999}");
+
+    // when:
+        ResponseOptions response = given().spec(request)
+                .put("/fraudcheck");
+
+    // then:
+        assertThat(response.statusCode()).isEqualTo(200);
+        assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*");
+    // and:
+        DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+        assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}");
+        assertThatJson(parsedJson).field("['rejection.reason']").isEqualTo("Amount too high");
+}

If you used the Groovy DSL, you can see, all the producer() parts of the Contract that were present in the +value(consumer(…​), producer(…​)) blocks got injected into the test. +In case of using YAML, the same applied for the matchers sections of the response.

Note that, on the producer side, you are also doing TDD. The expectations are expressed +in the form of a test. This test sends a request to our own application with the URL, +headers, and body defined in the contract. It also is expecting precisely defined values +in the response. In other words, you have the red part of red, green, and +refactor. It is time to convert the red into the green.

Write the missing implementation.

Because you know the expected input and expected output, you can write the missing +implementation:

@RequestMapping(value = "/fraudcheck", method = PUT)
+public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
+if (amountGreaterThanThreshold(fraudCheck)) {
+	return new FraudCheckResult(FraudCheckStatus.FRAUD, AMOUNT_TOO_HIGH);
+}
+return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
+}

When you execute ./mvnw clean install again, the tests pass. Since the Spring Cloud +Contract Verifier plugin adds the tests to the generated-test-sources, you can +actually run those tests from your IDE.

Deploy your app.

Once you finish your work, you can deploy your change. First, merge the branch:

$ git checkout master
+$ git merge --no-ff contract-change-pr
+$ git push origin master

Your CI might run something like ./mvnw clean deploy, which would publish both the +application and the stub artifacts.

85.4.4 Consumer Side (Loan Issuance) Final Step

As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):

Merge branch to master.

$ git checkout master
+$ git merge --no-ff contract-change-pr

Work online.

Now you can disable the offline work for Spring Cloud Contract Stub Runner and indicate +where the repository with your stubs is located. At this moment the stubs of the server +side are automatically downloaded from Nexus/Artifactory. You can switch off the value of +the workOffline parameter in your annotation. The following code shows an example of +achieving the same thing by changing the properties.

stubrunner:
+  ids: 'com.example:http-server-dsl:+:stubs:8080'
+  repositoryRoot: https://repo.spring.io/libs-snapshot

That’s it!

85.5 Dependencies

The best way to add dependencies is to use the proper starter dependency.

For stub-runner, use spring-cloud-starter-stub-runner. When you use a plugin, add +spring-cloud-starter-contract-verifier.

85.6 Additional Links

Here are some resources related to Spring Cloud Contract Verifier and Stub Runner. Note +that some may be outdated, because the Spring Cloud Contract Verifier project is under +constant development.

85.6.1 Spring Cloud Contract video

You can check out the video from the Warsaw JUG about Spring Cloud Contract:

85.6.2 Readings

85.7 Samples

You can find some samples at +samples.

86. Spring Cloud Contract FAQ

86.1 Why use Spring Cloud Contract Verifier and not X ?

For the time being Spring Cloud Contract Verifier is a JVM based tool. So it could be your first pick when you’re already creating +software for the JVM. This project has a lot of really interesting features but especially quite a few of them definitely make +Spring Cloud Contract Verifier stand out on the "market" of Consumer Driven Contract (CDC) tooling. Out of many the most interesting are:

  • Possibility to do CDC with messaging
  • Clear and easy to use, statically typed DSL
  • Possibility to copy paste your current JSON file to the contract and only edit its elements
  • Automatic generation of tests from the defined Contract
  • Stub Runner functionality - the stubs are automatically downloaded at runtime from Nexus / Artifactory
  • Spring Cloud integration - no discovery service is needed for integration tests

86.2 I don’t want to write a contract in Groovy!

No problem. You can write a contract in YAML!

86.3 What is this value(consumer(), producer()) ?

One of the biggest challenges related to stubs is their reusability. Only if they can be vastly used, will they serve their purpose. +What typically makes that difficult are the hard-coded values of request / response elements. For example dates or ids. +Imagine the following JSON request

{
+    "time" : "2016-10-10 20:10:15",
+    "id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
+    "body" : "foo"
+}

and JSON response

{
+    "time" : "2016-10-10 21:10:15",
+    "id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
+    "body" : "bar"
+}

Imagine the pain required to set proper value of the time field (let’s assume that this content is generated by the +database) by changing the clock in the system or providing stub implementations of data providers. The same is related +to the field called id. Will you create a stubbed implementation of UUID generator? Makes little sense…​

So as a consumer you would like to send a request that matches any form of a time or any UUID. That way your system +will work as usual - will generate data and you won’t have to stub anything out. Let’s assume that in case of the aforementioned +JSON the most important part is the body field. You can focus on that and provide matching for other fields. In other words +you would like the stub to work like this:

{
+    "time" : "SOMETHING THAT MATCHES TIME",
+    "id" : "SOMETHING THAT MATCHES UUID",
+    "body" : "foo"
+}

As far as the response goes as a consumer you need a concrete value that you can operate on. So such a JSON is valid

{
+    "time" : "2016-10-10 21:10:15",
+    "id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
+    "body" : "bar"
+}

As you could see in the previous sections we generate tests from contracts. So from the producer’s side the situation looks +much different. We’re parsing the provided contract and in the test we want to send a real request to your endpoints. +So for the case of a producer for the request we can’t have any sort of matching. We need concrete values that the +producer’s backend can work on. Such a JSON would be a valid one:

{
+    "time" : "2016-10-10 20:10:15",
+    "id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
+    "body" : "foo"
+}

On the other hand from the point of view of the validity of the contract the response doesn’t necessarily have to +contain concrete values of time or id. Let’s say that you generate those on the producer side - again, you’d +have to do a lot of stubbing to ensure that you always return the same values. That’s why from the producer’s side +what you might want is the following response:

{
+    "time" : "SOMETHING THAT MATCHES TIME",
+    "id" : "SOMETHING THAT MATCHES UUID",
+    "body" : "bar"
+}

How can you then provide one time a matcher for the consumer and a concrete value for the producer and vice versa? +In Spring Cloud Contract we’re allowing you to provide a dynamic value. That means that it can differ for both +sides of the communication. You can pass the values:

Either via the value method

value(consumer(...), producer(...))
+value(stub(...), test(...))
+value(client(...), server(...))

or using the $() method

$(consumer(...), producer(...))
+$(stub(...), test(...))
+$(client(...), server(...))

You can read more about this in the Contract DSL section.

Calling value() or $() tells Spring Cloud Contract that you will be passing a dynamic value. +Inside the consumer() method you pass the value that should be used on the consumer side (in the generated stub). +Inside the producer() method you pass the value that should be used on the producer side (in the generated test).

[Tip]Tip

If on one side you have passed the regular expression and you haven’t passed the other, then the +other side will get auto-generated.

Most often you will use that method together with the regex helper method. E.g. consumer(regex('[0-9]{10}')).

To sum it up the contract for the aforementioned scenario would look more or less like this (the regular expression +for time and UUID are simplified and most likely invalid but we want to keep things very simple in this example):

org.springframework.cloud.contract.spec.Contract.make {
+				request {
+					method 'GET'
+					url '/someUrl'
+					body([
+					    time : value(consumer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
+					    id: value(consumer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
+					    body: "foo"
+					])
+				}
+			response {
+				status 200
+				body([
+					    time : value(producer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
+					    id: value([producer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
+					    body: "bar"
+					])
+			}
+}
[Important]Important

Please read the Groovy docs related to JSON to understand how to +properly structure the request / response bodies.

86.4 How to do Stubs versioning?

86.4.1 API Versioning

Let’s try to answer a question what versioning really means. If you’re referring to the API version then there are +different approaches.

  • use Hypermedia, links and do not version your API by any means
  • pass versions through headers / urls

I will not try to answer a question which approach is better. Whatever suit your needs and allows you to generate +business value should be picked.

Let’s assume that you do version your API. In that case you should provide as many contracts as many versions you support. +You can create a subfolder for every version or append it to th contract name - whatever suits you more.

86.4.2 JAR versioning

If by versioning you mean the version of the JAR that contains the stubs then there are essentially two main approaches.

Let’s assume that you’re doing Continuous Delivery / Deployment which means that you’re generating a new version of +the jar each time you go through the pipeline and that jar can go to production at any time. For example your jar version +looks like this (it got built on the 20.10.2016 at 20:15:21) :

1.0.0.20161020-201521-RELEASE

In that case your generated stub jar will look like this.

1.0.0.20161020-201521-RELEASE-stubs.jar

In this case you should inside your application.yml or @AutoConfigureStubRunner when referencing stubs provide the + latest version of the stubs. You can do that by passing the + sign. Example

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})

If the versioning however is fixed (e.g. 1.0.4.RELEASE or 2.1.1) then you have to set the concrete value of the jar +version. Example for 2.1.1.

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:2.1.1:stubs:8080"})

86.4.3 Dev or prod stubs

You can manipulate the classifier to run the tests against current development version of the stubs of other services + or the ones that were deployed to production. If you alter your build to deploy the stubs with the prod-stubs classifier + once you reach production deployment then you can run tests in one case with dev stubs and one with prod stubs.

Example of tests using development version of stubs

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})

Example of tests using production version of stubs

@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:prod-stubs:8080"})

You can pass those values also via properties from your deployment pipeline.

86.5 Common repo with contracts

Another way of storing contracts other than having them with the producer is keeping them in a common place. +It can be related to security issues where the consumers can’t clone the producer’s code. Also if you keep +contracts in a single place then you, as a producer, will know how many consumers you have and which +consumer will you break with your local changes.

86.5.1 Repo structure

Let’s assume that we have a producer with coordinates com.example:server and 3 consumers: client1, +client2, client3. Then in the repository with common contracts you would have the following setup +(which you can checkout here:

├── com
+│   └── example
+│       └── server
+│           ├── client1
+│           │   └── expectation.groovy
+│           ├── client2
+│           │   └── expectation.groovy
+│           ├── client3
+│           │   └── expectation.groovy
+│           └── pom.xml
+├── mvnw
+├── mvnw.cmd
+├── pom.xml
+└── src
+    └── assembly
+        └── contracts.xml

As you can see the under the slash-delimited groupid / artifact id folder (com/example/server) you have +expectations of the 3 consumers (client1, client2 and client3). Expectations are the standard Groovy DSL +contract files as described throughout this documentation. This repository has to produce a JAR file that maps +one to one to the contents of the repo.

Example of a pom.xml inside the server folder.

<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example</groupId>
+	<artifactId>server</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+
+	<name>Server Stubs</name>
+	<description>POM used to install locally stubs for consumer side</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>1.5.21.RELEASE</version>
+		<relativePath />
+	</parent>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<java.version>1.8</java.version>
+		<spring-cloud-contract.version>1.2.8.BUILD-SNAPSHOT</spring-cloud-contract.version>
+		<spring-cloud-dependencies.version>1.3.11.BUILD-SNAPSHOT</spring-cloud-dependencies.version>
+		<excludeBuildFolders>true</excludeBuildFolders>
+	</properties>
+
+	<dependencyManagement>
+		<dependencies>
+			<dependency>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-dependencies</artifactId>
+				<version>${spring-cloud-dependencies.version}</version>
+				<type>pom</type>
+				<scope>import</scope>
+			</dependency>
+		</dependencies>
+	</dependencyManagement>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+				<version>${spring-cloud-contract.version}</version>
+				<extensions>true</extensions>
+				<configuration>
+					<!-- By default it would search under src/test/resources/ -->
+					<contractsDirectory>${project.basedir}</contractsDirectory>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+	<repositories>
+		<repository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-releases</id>
+			<name>Spring Releases</name>
+			<url>https://repo.spring.io/release</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+	</repositories>
+	<pluginRepositories>
+		<pluginRepository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-releases</id>
+			<name>Spring Releases</name>
+			<url>https://repo.spring.io/release</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+	</pluginRepositories>
+
+</project>

As you can see there are no dependencies other than the Spring Cloud Contract Maven Plugin. +Those poms are necessary for the consumer side to run mvn clean install -DskipTests to locally install + stubs of the producer project.

The pom.xml in the root folder can look like this:

<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example.standalone</groupId>
+	<artifactId>contracts</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+
+	<name>Contracts</name>
+	<description>Contains all the Spring Cloud Contracts, well, contracts. JAR used by the producers to generate tests and stubs</description>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+	</properties>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-assembly-plugin</artifactId>
+				<executions>
+					<execution>
+						<id>contracts</id>
+						<phase>prepare-package</phase>
+						<goals>
+							<goal>single</goal>
+						</goals>
+						<configuration>
+							<attach>true</attach>
+							<descriptor>${basedir}/src/assembly/contracts.xml</descriptor>
+							<!-- If you want an explicit classifier remove the following line -->
+							<appendAssemblyId>false</appendAssemblyId>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

It’s using the assembly plugin in order to build the JAR with all the contracts. Example of such setup is here:

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
+		  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	<id>project</id>
+	<formats>
+		<format>jar</format>
+	</formats>
+	<includeBaseDirectory>false</includeBaseDirectory>
+	<fileSets>
+		<fileSet>
+			<directory>${project.basedir}</directory>
+			<outputDirectory>/</outputDirectory>
+			<useDefaultExcludes>true</useDefaultExcludes>
+			<excludes>
+				<exclude>**/${project.build.directory}/**</exclude>
+				<exclude>mvnw</exclude>
+				<exclude>mvnw.cmd</exclude>
+				<exclude>.mvn/**</exclude>
+				<exclude>src/**</exclude>
+			</excludes>
+		</fileSet>
+	</fileSets>
+</assembly>

86.5.2 Workflow

The workflow would look similar to the one presented in the Step by step guide to CDC. The only difference + is that the producer doesn’t own the contracts anymore. So the consumer and the producer have to work on + common contracts in a common repository.

86.5.3 Consumer

When the consumer wants to work on the contracts offline, instead of cloning the producer code, the +consumer team clones the common repository, goes to the required producer’s folder (e.g. com/example/server) +and runs mvn clean install -DskipTests to install locally the stubs converted from the contracts.

[Tip]Tip

You need to have Maven installed locally

86.5.4 Producer

As a producer it’s enough to alter the Spring Cloud Contract Verifier to provide the URL and the dependency +of the JAR containing the contracts:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<configuration>
+		<contractsRepositoryUrl>http://link/to/your/nexus/or/artifactory/or/sth</contractsRepositoryUrl>
+		<contractDependency>
+			<groupId>com.example.standalone</groupId>
+			<artifactId>contracts</artifactId>
+		</contractDependency>
+	</configuration>
+</plugin>

With this setup the JAR with groupid com.example.standalone and artifactid contracts will be downloaded +from http://link/to/your/nexus/or/artifactory/or/sth. It will be then unpacked in a local temporary folder +and contracts present under the com/example/server will be picked as the ones used to generate the +tests and the stubs. Due to this convention the producer team will know which consumer teams will be broken +when some incompatible changes are done.

The rest of the flow looks the same.

86.6 Can I have multiple base classes for tests?

Yes! Check out the Different base classes for contracts sections +of either Gradle or Maven plugins.

86.7 How can I debug the request/response being sent by the generated tests client?

The generated tests all boil down to RestAssured in some form or fashion which relies on Apache HttpClient. HttpClient has a facility called wire logging which logs the entire request and response to HttpClient. Spring Boot has a logging common application property for doing this sort of thing, just add this to your application properties

logging.level.org.apache.http.wire=DEBUG

86.7.1 How can I debug the mapping/request/response being sent by WireMock?

Starting from version 1.2.0 we turn on WireMock logging to +info and the WireMock notifier to being verbose. Now you will +exactly know what request was received by WireMock server and which +matching response definition was picked.

To turn off this feature just bump WireMock logging to ERROR

logging.level.com.github.tomakehurst.wiremock=ERROR

86.7.2 How can I see what got registered in the HTTP server stub?

You can use the mappingsOutputFolder property on @AutoConfigureStubRunner or StubRunnerRule +to dump all mappings per artifact id. Also the port at which the given stub server was +started will be attached.

86.7.3 Can I reference the request from the response?

Yes! With version 1.1.0 we’ve added such a possibility. On the HTTP stub server side we’re providing support +for this for WireMock. In case of other HTTP server stubs you’ll have to implement the approach yourself.

86.7.4 Can I reference text from file?

Yes! With version 1.2.0 we’ve added such a possibility. It’s enough to call file(…​) method in the +DSL and provide a path relative to where the contract lays. +If you’re using YAML just use the bodyFromFile property.

87. Spring Cloud Contract Verifier Setup

You can set up Spring Cloud Contract Verifier in the following ways:

87.1 Gradle Project

To learn how to set up the Gradle project for Spring Cloud Contract Verifier, read the +following sections:

87.1.1 Prerequisites

In order to use Spring Cloud Contract Verifier with WireMock, you muse use either a +Gradle or a Maven plugin.

[Warning]Warning

If you want to use Spock in your projects, you must add separately the +spock-core and spock-spring modules. Check Spock +docs for more information

87.1.2 Add Gradle Plugin with Dependencies

To add a Gradle plugin with dependencies, use code similar to this:

buildscript {
+	repositories {
+		mavenCentral()
+	}
+	dependencies {
+	    classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}"
+		classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}"
+	}
+}
+
+apply plugin: 'groovy'
+apply plugin: 'spring-cloud-contract'
+
+dependencyManagement {
+	imports {
+		mavenBom "org.springframework.cloud:spring-cloud-contract-dependencies:${verifier_version}"
+	}
+}
+
+dependencies {
+	testCompile 'org.codehaus.groovy:groovy-all:2.4.6'
+	// example with adding Spock core and Spock Spring
+	testCompile 'org.spockframework:spock-core:1.0-groovy-2.4'
+	testCompile 'org.spockframework:spock-spring:1.0-groovy-2.4'
+	testCompile 'org.springframework.cloud:spring-cloud-starter-contract-verifier'
+}

87.1.3 Gradle and Rest Assured 2.0

By default, Rest Assured 3.x is added to the classpath. However, to use Rest Assured 2.x +you can add it to the plugins classpath, as shown here:

buildscript {
+	repositories {
+		mavenCentral()
+	}
+	dependencies {
+	    classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}"
+		classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}"
+		classpath "com.jayway.restassured:rest-assured:2.5.0"
+		classpath "com.jayway.restassured:spring-mock-mvc:2.5.0"
+	}
+}
+
+depenendencies {
+    // all dependencies
+    // you can exclude rest-assured from spring-cloud-contract-verifier
+    testCompile "com.jayway.restassured:rest-assured:2.5.0"
+    testCompile "com.jayway.restassured:spring-mock-mvc:2.5.0"
+}

That way, the plugin automatically sees that Rest Assured 2.x is present on the classpath +and modifies the imports accordingly.

87.1.4 Snapshot Versions for Gradle

Add the additional snapshot repository to your build.gradle to use snapshot versions, +which are automatically uploaded after every successful build, as shown here:

buildscript {
+	repositories {
+		mavenCentral()
+		mavenLocal()
+		maven { url "https://repo.spring.io/snapshot" }
+		maven { url "https://repo.spring.io/milestone" }
+		maven { url "https://repo.spring.io/release" }
+	}
+}

87.1.5 Add stubs

By default, Spring Cloud Contract Verifier is looking for stubs in the +src/test/resources/contracts directory.

The directory containing stub definitions is treated as a class name, and each stub +definition is treated as a single test. Spring Cloud Contract Verifier assumes that it +contains at least one level of directories that are to be used as the test class name. +If more than one level of nested directories is present, all except the last one is used +as the package name. For example, with following structure:

src/test/resources/contracts/myservice/shouldCreateUser.groovy
+src/test/resources/contracts/myservice/shouldReturnUser.groovy

Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService +with two methods:

  • shouldCreateUser()
  • shouldReturnUser()

87.1.6 Run the Plugin

The plugin registers itself to be invoked before a check task. If you want it to be +part of your build process, you need to do nothing more. If you just want to generate +tests, invoke the generateContractTests task.

87.1.7 Default Setup

The default Gradle Plugin setup creates the following Gradle part of the build (in +pseudocode):

contracts {
+    targetFramework = 'JUNIT'
+    testMode = 'MockMvc'
+    generatedTestSourcesDir = project.file("${project.buildDir}/generated-test-sources/contracts")
+    contractsDslDir = "${project.rootDir}/src/test/resources/contracts"
+    basePackageForTests = 'org.springframework.cloud.verifier.tests'
+    stubsOutputDir = project.file("${project.buildDir}/stubs")
+
+    // the following properties are used when you want to provide where the JAR with contract lays
+    contractDependency {
+        stringNotation = ''
+    }
+    contractsPath = ''
+    contractsWorkOffline = false
+    contractRepository {
+        cacheDownloadedContracts(true)
+    }
+}
+
+tasks.create(type: Jar, name: 'verifierStubsJar', dependsOn: 'generateClientStubs') {
+    baseName = project.name
+    classifier = contracts.stubsSuffix
+    from contractVerifier.stubsOutputDir
+}
+
+project.artifacts {
+    archives task
+}
+
+tasks.create(type: Copy, name: 'copyContracts') {
+    from contracts.contractsDslDir
+    into contracts.stubsOutputDir
+}
+
+verifierStubsJar.dependsOn 'copyContracts'
+
+publishing {
+    publications {
+        stubs(MavenPublication) {
+            artifactId project.name
+            artifact verifierStubsJar
+        }
+    }
+}

87.1.8 Configure Plugin

To change the default configuration, add a contracts snippet to your Gradle config, as +shown here:

contracts {
+	testMode = 'MockMvc'
+	baseClassForTests = 'org.mycompany.tests'
+	generatedTestSourcesDir = project.file('src/generatedContract')
+}

87.1.9 Configuration Options

  • testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, +which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to +Explicit for real HTTP calls.
  • imports: Creates an array with imports that should be included in generated tests +(for example ['org.myorg.Matchers']). By default, it creates an empty array.
  • staticImports: Creates an array with static imports that should be included in +generated tests(for example ['org.myorg.Matchers.*']). By default, it creates an empty +array.
  • basePackageForTests: Specifies the base package for all generated tests. If not set, +the value is picked from baseClassForTests’s package and from `packageWithBaseClasses. +If neither of these values are set, then the value is set to +org.springframework.cloud.contract.verifier.tests.
  • baseClassForTests: Creates a base class for all generated tests. By default, if you +use Spock classes, the class is spock.lang.Specification.
  • packageWithBaseClasses: Defines a package where all the base classes reside. This +setting takes precedence over baseClassForTests.
  • baseClassMappings: Explicitly maps a contract package to a FQN of a base class. This +setting takes precedence over packageWithBaseClasses and baseClassForTests.
  • ruleClassForTests: Specifies a rule that should be added to the generated test +classes.
  • ignoredFiles: Uses an Antmatcher to allow defining stub files for which processing +should be skipped. By default, it is an empty array.
  • contractsDslDir: Specifies the directory containing contracts written using the +GroovyDSL. By default, its value is $rootDir/src/test/resources/contracts.
  • generatedTestSourcesDir: Specifies the test source directory where tests generated +from the Groovy DSL should be placed. By default its value is +$buildDir/generated-test-sources/contractVerifier.
  • stubsOutputDir: Specifies the directory where the generated WireMock stubs from +the Groovy DSL should be placed.
  • targetFramework: Specifies the target test framework to be used. Currently, Spock and +JUnit are supported with JUnit being the default framework.

The following properties are used when you want to specify the location of the JAR +containing the contracts: +* contractDependency: Specifies the Dependency that provides +groupid:artifactid:version:classifier coordinates. You can use the contractDependency +closure to set it up. +* contractsPath: Specifies the path to the jar. If contract dependencies are + downloaded, the path defaults to groupid/artifactid where groupid is slash + separated. Otherwise, it scans contracts under the provided directory. +* contractsWorkOffline: Specifies whether to download the dependencies each time, so +that you can work online. In other words, it specifies whether to reuses the local Maven +repo.

87.1.10 Single Base Class for All Tests

When using Spring Cloud Contract Verifier in default MockMvc, you need to create a base +specification for all generated acceptance tests. In this class, you need to point to an +endpoint, which should be verified.

abstract class BaseMockMvcSpec extends Specification {
+
+	def setup() {
+		RestAssuredMockMvc.standaloneSetup(new PairIdController())
+	}
+
+	void isProperCorrelationId(Integer correlationId) {
+		assert correlationId == 123456
+	}
+
+	void isEmpty(String value) {
+		assert value == null
+	}
+
+}

If you use Explicit mode, you can use a base class to initialize the whole tested app +as you might see in regular integration tests. If you use the JAXRSCLIENT mode, this +base class should also contain a protected WebTarget webTarget field. Right now, the +only option to test the JAX-RS API is to start a web server.

87.1.11 Different Base Classes for Contracts

If your base classes differ between contracts, you can tell the Spring Cloud Contract +plugin which class should get extended by the autogenerated tests. You have two options:

  • Follow a convention by providing the packageWithBaseClasses
  • Provide explicit mapping via baseClassMappings

By Convention

The convention is such that if you have a contract under (for example) +src/test/resources/contract/foo/bar/baz/ and set the value of the +packageWithBaseClasses property to com.example.base, then Spring Cloud Contract +Verifier assumes that there is a BarBazBase class under the com.example.base package. +In other words, the system takes the last two parts of the package, if they exist, and +forms a class with a Base suffix. This rule takes precedence over baseClassForTests. +Here is an example of how it works in the contracts closure:

packageWithBaseClasses = 'com.example.base'

By Mapping

You can manually map a regular expression of the contract’s package to fully qualified +name of the base class for the matched contract. You have to provide a list called +baseClassMappings that consists baseClassMapping objects that takes a +contractPackageRegex to baseClassFQN mapping. Consider the following example:

baseClassForTests = "com.example.FooBase"
+baseClassMappings {
+	baseClassMapping('.*/com/.*', 'com.example.ComBase')
+	baseClassMapping('.*/bar/.*':'com.example.BarBase')
+}

Let’s assume that you have contracts under + - src/test/resources/contract/com/ + - src/test/resources/contract/foo/

By providing the baseClassForTests, we have a fallback in case mapping did not succeed. +(You could also provide the packageWithBaseClasses as a fallback.) That way, the tests +generated from src/test/resources/contract/com/ contracts extend the +com.example.ComBase, whereas the rest of the tests extend com.example.FooBase.

87.1.12 Invoking Generated Tests

To ensure that the provider side is compliant with defined contracts, you need to invoke:

./gradlew generateContractTests test

87.1.13 Spring Cloud Contract Verifier on the Consumer Side

In a consuming service, you need to configure the Spring Cloud Contract Verifier plugin +in exactly the same way as in case of provider. If you do not want to use Stub Runner +then you need to copy contracts stored in src/test/resources/contracts and generate +WireMock JSON stubs using:

./gradlew generateClientStubs
[Note]Note

The stubsOutputDir option has to be set for stub generation to work.

When present, JSON stubs can be used in automated tests of consuming a service.

@ContextConfiguration(loader == SpringApplicationContextLoader, classes == Application)
+class LoanApplicationServiceSpec extends Specification {
+
+ @ClassRule
+ @Shared
+ WireMockClassRule wireMockRule == new WireMockClassRule()
+
+ @Autowired
+ LoanApplicationService sut
+
+ def 'should successfully apply for loan'() {
+   given:
+ 	LoanApplication application =
+			new LoanApplication(client: new Client(clientPesel: '12345678901'), amount: 123.123)
+   when:
+	LoanApplicationResult loanApplication == sut.loanApplication(application)
+   then:
+	loanApplication.loanApplicationStatus == LoanApplicationStatus.LOAN_APPLIED
+	loanApplication.rejectionReason == null
+ }
+}

LoanApplication makes a call to FraudDetection service. This request is handled by a +WireMock server configured with stubs generated by Spring Cloud Contract Verifier.

87.2 Maven Project

To learn how to set up the Maven project for Spring Cloud Contract Verifier, read the +following sections:

87.2.1 Add maven plugin

Add the Spring Cloud Contract BOM in a fashion similar to this:

<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>${spring-cloud-dependencies.version}</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

Next, add the Spring Cloud Contract Verifier Maven plugin:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+</plugin>

You can read more in the +Spring +Cloud Contract Maven Plugin Documentation.

87.2.2 Maven and Rest Assured 2.0

By default, Rest Assured 3.x is added to the classpath. However, you can use Rest +Assured 2.x by adding it to the plugins classpath, as shown here:

<plugin>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+    <version>${spring-cloud-contract.version}</version>
+    <extensions>true</extensions>
+    <configuration>
+        <packageWithBaseClasses>com.example</packageWithBaseClasses>
+    </configuration>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.cloud</groupId>
+            <artifactId>spring-cloud-contract-verifier</artifactId>
+            <version>${spring-cloud-contract.version}</version>
+        </dependency>
+        <dependency>
+           <groupId>com.jayway.restassured</groupId>
+           <artifactId>rest-assured</artifactId>
+           <version>2.5.0</version>
+           <scope>compile</scope>
+        </dependency>
+        <dependency>
+           <groupId>com.jayway.restassured</groupId>
+           <artifactId>spring-mock-mvc</artifactId>
+           <version>2.5.0</version>
+           <scope>compile</scope>
+        </dependency>
+    </dependencies>
+</plugin>
+
+<dependencies>
+    <!-- all dependencies -->
+    <!-- you can exclude rest-assured from spring-cloud-contract-verifier -->
+    <dependency>
+       <groupId>com.jayway.restassured</groupId>
+       <artifactId>rest-assured</artifactId>
+       <version>2.5.0</version>
+       <scope>test</scope>
+    </dependency>
+    <dependency>
+       <groupId>com.jayway.restassured</groupId>
+       <artifactId>spring-mock-mvc</artifactId>
+       <version>2.5.0</version>
+       <scope>test</scope>
+    </dependency>
+</dependencies>

That way, the plugin automatically sees that Rest Assured 3.x is present on the classpath +and modifies the imports accordingly.

87.2.3 Snapshot versions for Maven

For Snapshot and Milestone versions, you have to add the following section to your +pom.xml, as shown here:

<repositories>
+	<repository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+</repositories>
+<pluginRepositories>
+	<pluginRepository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+</pluginRepositories>

87.2.4 Add stubs

By default, Spring Cloud Contract Verifier is looking for stubs in the +src/test/resources/contracts directory. The directory containing stub definitions is +treated as a class name, and each stub definition is treated as a single test. We assume +that it contains at least one directory to be used as test class name. If there is more +than one level of nested directories, all except the last one is used as package name. +For example, with following structure:

src/test/resources/contracts/myservice/shouldCreateUser.groovy
+src/test/resources/contracts/myservice/shouldReturnUser.groovy

Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService +with two methods

  • shouldCreateUser()
  • shouldReturnUser()

87.2.5 Run plugin

The plugin goal generateTests is assigned to be invoked in the phase called +generate-test-sources. If you want it to be part of your build process, you need not do +anything. If you just want to generate tests, invoke the generateTests goal.

87.2.6 Configure plugin

To change the default configuration, just add a configuration section to the plugin +definition or the execution definition, as shown here:

<plugin>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+    <executions>
+        <execution>
+            <goals>
+                <goal>convert</goal>
+                <goal>generateStubs</goal>
+                <goal>generateTests</goal>
+            </goals>
+        </execution>
+    </executions>
+    <configuration>
+        <basePackageForTests>org.springframework.cloud.verifier.twitter.place</basePackageForTests>
+        <baseClassForTests>org.springframework.cloud.verifier.twitter.place.BaseMockMvcSpec</baseClassForTests>
+    </configuration>
+</plugin>

87.2.7 Configuration Options

  • testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, +which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to +Explicit for real HTTP calls.
  • basePackageForTests: Specifies the base package for all generated tests. If not set, +the value is picked from baseClassForTests’s package and from `packageWithBaseClasses. +If neither of these values are set, then the value is set to +org.springframework.cloud.contract.verifier.tests.
  • ruleClassForTests: Specifies a rule that should be added to the generated test +classes.
  • baseClassForTests: Creates a base class for all generated tests. By default, if you +use Spock classes, the class is spock.lang.Specification.
  • contractsDirectory: Specifies a directory containing contracts written with the +GroovyDSL. The default directory is /src/test/resources/contracts.
  • testFramework: Specifies the target test framework to be used. Currently, Spock and +JUnit are supported with JUnit being the default framework
  • packageWithBaseClasses: Defines a package where all the base classes reside. This +setting takes precedence over baseClassForTests. The convention is such that, if you +have a contract under (for example) src/test/resources/contract/foo/bar/baz/ and set +the value of the packageWithBaseClasses property to com.example.base, then Spring +Cloud Contract Verifier assumes that there is a BarBazBase class under the +com.example.base package. In other words, the system takes the last two parts of the +package, if they exist, and forms a class with a Base suffix.
  • baseClassMappings: Specifies a list of base class mappings that provide +contractPackageRegex, which is checked against the package where the contract is +located, and baseClassFQN, which maps to the fully qualified name of the base class for +the matched contract. For example, if you have a contract under +src/test/resources/contract/foo/bar/baz/ and map the property +.* → com.example.base.BaseClass, then the test class generated from these contracts +extends com.example.base.BaseClass. This setting takes precedence over +packageWithBaseClasses and baseClassForTests.

If you want to download your contract definitions from a Maven repository, you can use +the following options:

  • contractDependency: The contract dependency that contains all the packaged contracts.
  • contractsPath: The path to the concrete contracts in the JAR with packaged contracts. +Defaults to groupid/artifactid where gropuid is slash separated.
  • contractsWorkOffline: Dictates whether the dependencies should be downloaded or the +local Maven artifacts should be reused.
  • contractsRepositoryUrl: URL to a repo with the artifacts that have contracts. If it is not provided, +use the current Maven ones.
  • contractsRepositoryUsername: The user name to be used to connect to the repo with contracts.
  • contractsRepositoryPassword: The password to be used to connect to the repo with contracts.
  • contractsRepositoryProxyHost: The proxy host to be used to connect to the repo with contracts.
  • contractsRepositoryProxyPort: The proxy port to be used to connect to the repo with contracts.

We cache only non-snapshot, explicitly provided versions (for example ++ or 1.0.0.BUILD-SNAPSHOT won’t get cached). By default, this feature is turned on.

87.2.8 Single Base Class for All Tests

When using Spring Cloud Contract Verifier in default MockMvc, you need to create a base +specification for all generated acceptance tests. In this class, you need to point to an +endpoint, which should be verified.

package org.mycompany.tests
+
+import org.mycompany.ExampleSpringController
+import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc
+import spock.lang.Specification
+
+class  MvcSpec extends Specification {
+  def setup() {
+   RestAssuredMockMvc.standaloneSetup(new ExampleSpringController())
+  }
+}

If you use Explicit mode, you can use a base class to initialize the whole tested app +similarly, as you might find in regular integration tests. If you use the JAXRSCLIENT +mode, this base class should also contain a protected WebTarget webTarget field. Right +now, the only option to test the JAX-RS API is to start a web server.

87.2.9 Different base classes for contracts

If your base classes differ between contracts, you can tell the Spring Cloud Contract +plugin which class should get extended by the autogenerated tests. You have two options:

  • Follow a convention by providing the packageWithBaseClasses
  • provide explicit mapping via baseClassMappings

By Convention

The convention is such that if you have a contract under (for example) +src/test/resources/contract/foo/bar/baz/ and set the value of the +packageWithBaseClasses property to com.example.base, then Spring Cloud Contract +Verifier assumes that there is a BarBazBase class under the com.example.base package. +In other words, the system takes the last two parts of the package, if they exist, and +forms a class with a Base suffix. This rule takes precedence over baseClassForTests. +Here is an example of how it works in the contracts closure:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<configuration>
+		<packageWithBaseClasses>hello</packageWithBaseClasses>
+	</configuration>
+</plugin>

By Mapping

You can manually map a regular expression of the contract’s package to fully qualified +name of the base class for the matched contract. You have to provide a list called +baseClassMappings that consists baseClassMapping objects that takes a +contractPackageRegex to baseClassFQN mapping. Consider the following example:

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<configuration>
+		<baseClassForTests>com.example.FooBase</baseClassForTests>
+		<baseClassMappings>
+			<baseClassMapping>
+				<contractPackageRegex>.*com.*</contractPackageRegex>
+				<baseClassFQN>com.example.TestBase</baseClassFQN>
+			</baseClassMapping>
+		</baseClassMappings>
+	</configuration>
+</plugin>

Assume that you have contracts under these two locations: +* src/test/resources/contract/com/ +* src/test/resources/contract/foo/

By providing the baseClassForTests, we have a fallback in case mapping did not succeed. +(You can also provide the packageWithBaseClasses as a fallback.) That way, the tests +generated from src/test/resources/contract/com/ contracts extend the +com.example.ComBase, whereas the rest of the tests extend com.example.FooBase.

87.2.10 Invoking generated tests

The Spring Cloud Contract Maven Plugin generates verification code in a directory called +/generated-test-sources/contractVerifier and attaches this directory to testCompile +goal.

For Groovy Spock code, use the following:

<plugin>
+	<groupId>org.codehaus.gmavenplus</groupId>
+	<artifactId>gmavenplus-plugin</artifactId>
+	<version>1.5</version>
+	<executions>
+		<execution>
+			<goals>
+				<goal>testCompile</goal>
+			</goals>
+		</execution>
+	</executions>
+	<configuration>
+		<testSources>
+			<testSource>
+				<directory>${project.basedir}/src/test/groovy</directory>
+				<includes>
+					<include>**/*.groovy</include>
+				</includes>
+			</testSource>
+			<testSource>
+				<directory>${project.build.directory}/generated-test-sources/contractVerifier</directory>
+				<includes>
+					<include>**/*.groovy</include>
+				</includes>
+			</testSource>
+		</testSources>
+	</configuration>
+</plugin>

To ensure that provider side is compliant with defined contracts, you need to invoke +mvn generateTest test.

87.2.11 Maven Plugin and STS

If you see the following exception while using STS:

STS Exception

When you click on the error marker you should see something like this:

 plugin:1.1.0.M1:convert:default-convert:process-test-resources) org.apache.maven.plugin.PluginExecutionException: Execution default-convert of goal org.springframework.cloud:spring-
+ cloud-contract-maven-plugin:1.1.0.M1:convert failed. at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145) at
+ org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331) at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362) at
+...
+ org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.lang.NullPointerException at
+ org.eclipse.m2e.core.internal.builder.plexusbuildapi.EclipseIncrementalBuildContext.hasDelta(EclipseIncrementalBuildContext.java:53) at
+ org.sonatype.plexus.build.incremental.ThreadBuildContext.hasDelta(ThreadBuildContext.java:59) at

In order to fix this issue, provide the following section in your pom.xml:

<build>
+    <pluginManagement>
+        <plugins>
+            <!--This plugin's configuration is used to store Eclipse m2e settings
+                only. It has no influence on the Maven build itself. -->
+            <plugin>
+                <groupId>org.eclipse.m2e</groupId>
+                <artifactId>lifecycle-mapping</artifactId>
+                <version>1.0.0</version>
+                <configuration>
+                    <lifecycleMappingMetadata>
+                        <pluginExecutions>
+                             <pluginExecution>
+                                <pluginExecutionFilter>
+                                    <groupId>org.springframework.cloud</groupId>
+                                    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+                                    <versionRange>[1.0,)</versionRange>
+                                    <goals>
+                                        <goal>convert</goal>
+                                    </goals>
+                                </pluginExecutionFilter>
+                                <action>
+                                    <execute />
+                                </action>
+                             </pluginExecution>
+                        </pluginExecutions>
+                    </lifecycleMappingMetadata>
+                </configuration>
+            </plugin>
+        </plugins>
+    </pluginManagement>
+</build>

87.3 Stubs and Transitive Dependencies

The Maven and Gradle plugin that add the tasks that create the stubs jar for you. One +problem that arises is that, when reusing the stubs, you can mistakenly import all of +that stub’s dependencies. When building a Maven artifact, even though you have a couple +of different jars, all of them share one pom:

├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar
+├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar.sha1
+├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar
+├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar.sha1
+├── github-webhook-0.0.1.BUILD-SNAPSHOT.jar
+├── github-webhook-0.0.1.BUILD-SNAPSHOT.pom
+├── github-webhook-0.0.1.BUILD-SNAPSHOT-stubs.jar
+├── ...
+└── ...

There are three possibilities of working with those dependencies so as not to have any +issues with transitive dependencies:

  • Mark all application dependencies as optional
  • Create a separate artifactid for the stubs
  • Exclude dependencies on the consumer side

Mark all application dependencies as optional

If, in the github-webhook application, you mark all of your dependencies as optional, +when you include the github-webhook stubs in another application (or when that +dependency gets downloaded by Stub Runner) then, since all of the dependencies are +optional, they will not get downloaded.

Create a separate artifactid for the stubs

If you create a separate artifactid, then you can set it up in whatever way you wish. +For example, you might decide to have no dependencies at all.

Exclude dependencies on the consumer side

As a consumer, if you add the stub dependency to your classpath, you can explicitly +exclude the unwanted dependencies.

87.4 CI Server setup

When fetching stubs / contracts in a CI, shared environment, what might happen is that +both the producer and the consumer reuse the same local Maven repository. Due to this, +the framework, responsible for downloading a stub JAR from remote location, +can’t decide which JAR should be picked, local or remote one. That caused +the "The artifact was found in the local repository but you have explicitly +stated that it should be downloaded from a remote one" exception +and failed the build.

For such cases we’re introducing the property mechanism:

  • via stubrunner.snapshot-check-skip system property
  • via STUBRUNNER_SNAPSHOT_CHECK_SKIP environment variable

if either of these values is set to true, then the stub downloader will not +verify the origin of the downloaded JAR.

87.5 Scenarios

You can handle scenarios with Spring Cloud Contract Verifier. All you need to do is to +stick to the proper naming convention while creating your contracts. The convention +requires including an order number followed by an underscore. This will work regardles + of whether you’re working with YAML or Groovy. Example:

my_contracts_dir\
+  scenario1\
+    1_login.groovy
+    2_showCart.groovy
+    3_logout.groovy

Such a tree causes Spring Cloud Contract Verifier to generate WireMock’s scenario with a +name of scenario1 and the three following steps:

  1. login marked as Started pointing to…​
  2. showCart marked as Step1 pointing to…​
  3. logout marked as Step2 which will close the scenario.

More details about WireMock scenarios can be found at +https://wiremock.org/stateful-behaviour.html

Spring Cloud Contract Verifier also generates tests with a guaranteed order of execution.

87.6 Docker Project

We’re publishing a springcloud/spring-cloud-contract Docker image +that contains a project that will generate tests and execute them in EXPLICIT mode +against a running application.

[Tip]Tip

The EXPLICIT mode means that the tests generated from contracts will send +real requests and not the mocked ones.

87.6.1 Short intro to Maven, JARs and Binary storage

Since the Docker image can be used by non JVM projects, it’s good to +explain the basic terms behind Spring Cloud Contract packaging defaults.

Part of the following definitions were taken from the Maven Glossary

  • Project: Maven thinks in terms of projects. Everything that you +will build are projects. Those projects follow a well defined +“Project Object Model”. Projects can depend on other projects, +in which case the latter are called “dependencies”. A project may +consistent of several subprojects, however these subprojects are still +treated equally as projects.
  • Artifact: An artifact is something that is either produced or used +by a project. Examples of artifacts produced by Maven for a project +include: JARs, source and binary distributions. Each artifact +is uniquely identified by a group id and an artifact ID which is +unique within a group.
  • JAR: JAR stands for Java ARchive. It’s a format based on +the ZIP file format. Spring Cloud Contract packages the contracts and generated +stubs in a JAR file.
  • GroupId: A group ID is a universally unique identifier for a project. +While this is often just the project name (eg. commons-collections), +it is helpful to use a fully-qualified package name to distinguish it +from other projects with a similar name (eg. org.apache.maven). +Typically, when published to the Artifact Manager, the GroupId will get +slash separated and form part of the URL. E.g. for group id com.example +and artifact id application would be /com/example/application/.
  • Classifier: The Maven dependency notation looks as follows: +groupId:artifactId:version:classifier. The classifier is additional suffix +passed to the dependency. E.g. stubs, sources. The same dependency +e.g. com.example:application can produce multiple artifacts that +differ from each other with the classifier.
  • Artifact manager: When you generate binaries / sources / packages, you would +like them to be available for others to download / reference or reuse. In case +of the JVM world those artifacts would be JARs, for Ruby these are gems +and for Docker those would be Docker images. You can store those artifacts +in a manager. Examples of such managers can be Artifactory +or Nexus.

87.6.2 How it works

The image searches for contracts under the /contracts folder. +The output from running the tests will be available under +/spring-cloud-contract/build folder (it’s useful for debugging +purposes).

It’s enough for you to mount your contracts, pass the environment variables + and the image will:

  • generate the contract tests
  • execute the tests against the provided URL
  • generate the WireMock stubs
  • (optional - turned on by default) publish the stubs to a Artifact Manager

Environment Variables

The Docker image requires some environment variables to point to +your running application, to the Artifact manager instance etc.

  • PROJECT_GROUP - your project’s group id. Defaults to com.example
  • PROJECT_VERSION - your project’s version. Defaults to 0.0.1-SNAPSHOT
  • PROJECT_NAME - artifact id. Defaults to example
  • REPO_WITH_BINARIES_URL - URL of your Artifact Manager. Defaults to http://localhost:8081/artifactory/libs-release-local +which is the default URL of Artifactory running locally
  • REPO_WITH_BINARIES_USERNAME - (optional) username when the Artifact Manager is secured
  • REPO_WITH_BINARIES_PASSWORD - (optional) password when the Artifact Manager is secured
  • PUBLISH_ARTIFACTS - if set to true then will publish artifact to binary storage. Defaults to true.

These environment variables are used when contracts lay in an external repository. To enable +this feature you must set the EXTERNAL_CONTRACTS_ARTIFACT_ID environment variable.

  • EXTERNAL_CONTRACTS_GROUP_ID - group id of the project with contracts. Defaults to com.example
  • EXTERNAL_CONTRACTS_ARTIFACT_ID- artifact id of the project with contracts.
  • EXTERNAL_CONTRACTS_CLASSIFIER- classifier of the project with contracts. Empty by default
  • EXTERNAL_CONTRACTS_VERSION - version of the project with contracts. Defaults to +, equivalent to picking the latest
  • EXTERNAL_CONTRACTS_REPO_WITH_BINARIES_URL - URL of your Artifact Manager. Defaults to value of REPO_WITH_BINARIES_URL env var. +If that’s not set, defaults to http://localhost:8081/artifactory/libs-release-local +which is the default URL of Artifactory running locally
  • EXTERNAL_CONTRACTS_PATH - path to contracts for the given project, inside the project with contracts. +Defaults to slash separated EXTERNAL_CONTRACTS_GROUP_ID concatenated with / and EXTERNAL_CONTRACTS_ARTIFACT_ID. E.g. +for group id foo.bar and artifact id baz, would result in foo/bar/baz contracts path.
  • EXTERNAL_CONTRACTS_WORK_OFFLINE - if set to true then will retrieve artifact with contracts +from the container’s .m2. Mount your local .m2 as a volume available at the container’s /root/.m2 path. +You must not set both EXTERNAL_CONTRACTS_WORK_OFFLINE and EXTERNAL_CONTRACTS_REPO_WITH_BINARIES_URL.

These environment variables are used when tests are executed:

  • APPLICATION_BASE_URL - url against which tests should be executed. +Remember that it has to be accessible from the Docker container (e.g. localhost +will not work)
  • APPLICATION_USERNAME - (optional) username for basic authentication to your application
  • APPLICATION_PASSWORD - (optional) password for basic authentication to your application

87.6.3 Example of usage

Let’s take a look at a simple MVC application

$ git clone https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs
+$ cd bookstore

The contracts are available under /contracts folder.

87.6.4 Server side (nodejs)

Since we want to run tests, we could just execute:

$ npm test

however, for learning purposes, let’s split it into pieces:

# Stop docker infra (nodejs, artifactory)
+$ ./stop_infra.sh
+# Start docker infra (nodejs, artifactory)
+$ ./setup_infra.sh
+
+# Kill & Run app
+$ pkill -f "node app"
+$ nohup node app &
+
+# Prepare environment variables
+$ SC_CONTRACT_DOCKER_VERSION="..."
+$ APP_IP="192.168.0.100"
+$ APP_PORT="3000"
+$ ARTIFACTORY_PORT="8081"
+$ APPLICATION_BASE_URL="http://${APP_IP}:${APP_PORT}"
+$ ARTIFACTORY_URL="http://${APP_IP}:${ARTIFACTORY_PORT}/artifactory/libs-release-local"
+$ CURRENT_DIR="$( pwd )"
+$ CURRENT_FOLDER_NAME=${PWD##*/}
+$ PROJECT_VERSION="0.0.1.RELEASE"
+
+# Execute contract tests
+$ docker run  --rm -e "APPLICATION_BASE_URL=${APPLICATION_BASE_URL}" -e "PUBLISH_ARTIFACTS=true" -e "PROJECT_NAME=${CURRENT_FOLDER_NAME}" -e "REPO_WITH_BINARIES_URL=${ARTIFACTORY_URL}" -e "PROJECT_VERSION=${PROJECT_VERSION}" -v "${CURRENT_DIR}/contracts/:/contracts:ro" -v "${CURRENT_DIR}/node_modules/spring-cloud-contract/output:/spring-cloud-contract-output/" springcloud/spring-cloud-contract:"${SC_CONTRACT_DOCKER_VERSION}"
+
+# Kill app
+$ pkill -f "node app"

What will happen is that via bash scripts:

  • infrastructure will be set up (MongoDb, Artifactory). +In real life scenario you would just run the NodeJS application +with mocked database. In this example we want to show how we can +benefit from Spring Cloud Contract in no time.

  • due to those constraints the contracts also represent the +stateful situation

    • first request is a POST that causes data to get inserted to the database
    • second request is a GET that returns a list of data with 1 previously inserted element
  • the NodeJS application will be started (on port 3000)

  • contract tests will be generated via Docker and tests +will be executed against the running application

    • the contracts will be taken from /contracts folder.
    • the output of the test execution is available under +node_modules/spring-cloud-contract/output.
  • the stubs will be uploaded to Artifactory. You can check them out +under http://localhost:8081/artifactory/libs-release-local/com/example/bookstore/0.0.1.RELEASE/ . +The stubs will be here http://localhost:8081/artifactory/libs-release-local/com/example/bookstore/0.0.1.RELEASE/bookstore-0.0.1.RELEASE-stubs.jar.

To see how the client side looks like check out the Section 89.9, “Stub Runner Docker” section.

88. Spring Cloud Contract Verifier Messaging

Spring Cloud Contract Verifier lets you verify applications that uses messaging as a +means of communication. All of the integrations shown in this document work with Spring, +but you can also create one of your own and use that.

88.1 Integrations

You can use one of the following four integration configurations:

  • Apache Camel
  • Spring Integration
  • Spring Cloud Stream
  • Spring AMQP

Since we use Spring Boot, if you have added one of these libraries to the classpath, all +the messaging configuration is automatically set up.

[Important]Important

Remember to put @AutoConfigureMessageVerifier on the base class of your +generated tests. Otherwise, messaging part of Spring Cloud Contract Verifier does not +work.

[Important]Important

If you want to use Spring Cloud Stream, remember to add a dependency on +org.springframework.cloud:spring-cloud-stream-test-support, as shown here:

Maven.  +

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-stream-test-support</artifactId>
+    <scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile "org.springframework.cloud:spring-cloud-stream-test-support"

+

88.2 Manual Integration Testing

The main interface used by the tests is +org.springframework.cloud.contract.verifier.messaging.MessageVerifier. +It defines how to send and receive messages. You can create your own implementation to +achieve the same goal.

In a test, you can inject a ContractVerifierMessageExchange to send and receive +messages that follow the contract. Then add @AutoConfigureMessageVerifier to your test. +Here’s an example:

@RunWith(SpringTestRunner.class)
+@SpringBootTest
+@AutoConfigureMessageVerifier
+public static class MessagingContractTests {
+
+  @Autowired
+  private MessageVerifier verifier;
+  ...
+}
[Note]Note

If your tests require stubs as well, then @AutoConfigureStubRunner includes the +messaging configuration, so you only need the one annotation.

88.3 Publisher-Side Test Generation

Having the input or outputMessage sections in your DSL results in creation of tests +on the publisher’s side. By default, JUnit tests are created. However, there is also a +possibility to create Spock tests.

There are 3 main scenarios that we should take into consideration:

  • Scenario 1: There is no input message that produces an output message. The output +message is triggered by a component inside the application (for example, scheduler).
  • Scenario 2: The input message triggers an output message.
  • Scenario 3: The input message is consumed and there is no output message.
[Important]Important

The destination passed to messageFrom or sentTo can have different +meanings for different messaging implementations. For Stream and Integration it is +first resolved as a destination of a channel. Then, if there is no such destination +it is resolved as a channel name. For Camel, that’s a certain component (for example, +jms).

88.3.1 Scenario 1: No Input Message

Here is an example for Camel. For the given contract:

Groovy DSL.  +

def contractDsl = Contract.make {
+	label 'some_label'
+	input {
+		triggeredBy('bookReturnedTriggered()')
+	}
+	outputMessage {
+		sentTo('activemq:output')
+		body('''{ "bookName" : "foo" }''')
+		headers {
+			header('BOOK-NAME', 'foo')
+			messagingContentType(applicationJson())
+		}
+	}
+}

+

YAML.  +

label: some_label
+input:
+  triggeredBy: bookReturnedTriggered
+outputMessage:
+  sentTo: activemq:output
+  body:
+    bookName: foo
+  headers:
+    BOOK-NAME: foo
+    contentType: application/json

+

The following JUnit test is created:

'''
+ // when:
+  bookReturnedTriggered();
+
+ // then:
+  ContractVerifierMessage response = contractVerifierMessaging.receive("activemq:output");
+  assertThat(response).isNotNull();
+  assertThat(response.getHeader("BOOK-NAME")).isNotNull();
+  assertThat(response.getHeader("BOOK-NAME").toString()).isEqualTo("foo");
+  assertThat(response.getHeader("contentType")).isNotNull();
+  assertThat(response.getHeader("contentType").toString()).isEqualTo("application/json");
+ // and:
+  DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
+  assertThatJson(parsedJson).field("bookName").isEqualTo("foo");
+'''

And the following Spock test would be created:

'''
+ when:
+  bookReturnedTriggered()
+
+ then:
+  ContractVerifierMessage response = contractVerifierMessaging.receive('activemq:output')
+  assert response != null
+  response.getHeader('BOOK-NAME')?.toString()  == 'foo'
+  response.getHeader('contentType')?.toString()  == 'application/json'
+ and:
+  DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
+  assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
+
+'''

88.3.2 Scenario 2: Output Triggered by Input

Here is an example for Camel. For the given contract:

Groovy DSL.  +

def contractDsl = Contract.make {
+	label 'some_label'
+	input {
+		messageFrom('jms:input')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('jms:output')
+		body([
+				bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

+

YAML.  +

label: some_label
+input:
+  messageFrom: jms:input
+  messageBody:
+    bookName: 'foo'
+  messageHeaders:
+    sample: header
+outputMessage:
+  sentTo: jms:output
+  body:
+    bookName: foo
+  headers:
+    BOOK-NAME: foo

+

The following JUnit test is created:

'''
+// given:
+ ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+  "{\\"bookName\\":\\"foo\\"}"
+, headers()
+  .header("sample", "header"));
+
+// when:
+ contractVerifierMessaging.send(inputMessage, "jms:input");
+
+// then:
+ ContractVerifierMessage response = contractVerifierMessaging.receive("jms:output");
+ assertThat(response).isNotNull();
+ assertThat(response.getHeader("BOOK-NAME")).isNotNull();
+ assertThat(response.getHeader("BOOK-NAME").toString()).isEqualTo("foo");
+// and:
+ DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
+ assertThatJson(parsedJson).field("bookName").isEqualTo("foo");
+'''

And the following Spock test would be created:

"""\
+given:
+   ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+    '''{"bookName":"foo"}''',
+    ['sample': 'header']
+  )
+
+when:
+   contractVerifierMessaging.send(inputMessage, 'jms:input')
+
+then:
+   ContractVerifierMessage response = contractVerifierMessaging.receive('jms:output')
+   assert response !- null
+   response.getHeader('BOOK-NAME')?.toString()  == 'foo'
+and:
+   DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
+   assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
+"""

88.3.3 Scenario 3: No Output Message

Here is an example for Camel. For the given contract:

Groovy DSL.  +

def contractDsl = Contract.make {
+	label 'some_label'
+	input {
+		messageFrom('jms:delete')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+		assertThat('bookWasDeleted()')
+	}
+}

+

YAML.  +

label: some_label
+input:
+  messageFrom: jms:delete
+  messageBody:
+    bookName: 'foo'
+  messageHeaders:
+    sample: header
+  assertThat: bookWasDeleted()

+

The following JUnit test is created:

'''
+// given:
+ ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+	"{\\"bookName\\":\\"foo\\"}"
+, headers()
+	.header("sample", "header"));
+
+// when:
+ contractVerifierMessaging.send(inputMessage, "jms:delete");
+
+// then:
+ bookWasDeleted();
+'''

And the following Spock test would be created:

'''
+given:
+	 ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
+		\'\'\'{"bookName":"foo"}\'\'\',
+		['sample': 'header']
+	)
+
+when:
+	 contractVerifierMessaging.send(inputMessage, 'jms:delete')
+
+then:
+	 noExceptionThrown()
+	 bookWasDeleted()
+'''

88.4 Consumer Stub Generation

Unlike the HTTP part, in messaging, we need to publish the Groovy DSL inside the JAR with +a stub. Then it is parsed on the consumer side and proper stubbed routes are created.

For more information, see +the +Stub Runner Messaging sections.

Maven.  +

<dependencies>
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-starter-stream-rabbit</artifactId>
+	</dependency>
+
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
+		<scope>test</scope>
+	</dependency>
+	<dependency>
+		<groupId>org.springframework.cloud</groupId>
+		<artifactId>spring-cloud-stream-test-support</artifactId>
+		<scope>test</scope>
+	</dependency>
+</dependencies>
+
+<dependencyManagement>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-dependencies</artifactId>
+			<version>Edgware.BUILD-SNAPSHOT</version>
+			<type>pom</type>
+			<scope>import</scope>
+		</dependency>
+	</dependencies>
+</dependencyManagement>

+

Gradle.  +

ext {
+	contractsDir = file("mappings")
+	stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/")
+}
+
+// Automatically added by plugin:
+// copyContracts - copies contracts to the output folder from which JAR will be created
+// verifierStubsJar - JAR with a provided stub suffix
+// the presented publication is also added by the plugin but you can modify it as you wish
+
+publishing {
+	publications {
+		stubs(MavenPublication) {
+			artifactId "${project.name}-stubs"
+			artifact verifierStubsJar
+		}
+	}
+}

+

89. Spring Cloud Contract Stub Runner

One of the issues that you might encounter while using Spring Cloud Contract Verifier is +passing the generated WireMock JSON stubs from the server side to the client side (or to +various clients). The same takes place in terms of client-side generation for messaging.

Copying the JSON files and setting the client side for messaging manually is out of the +question. That is why we introduced Spring Cloud Contract Stub Runner. It can +automatically download and run the stubs for you.

89.1 Snapshot versions

Add the additional snapshot repository to your build.gradle file to use snapshot +versions, which are automatically uploaded after every successful build:

Maven.  +

<repositories>
+	<repository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+	<repository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</repository>
+</repositories>
+<pluginRepositories>
+	<pluginRepository>
+		<id>spring-snapshots</id>
+		<name>Spring Snapshots</name>
+		<url>https://repo.spring.io/snapshot</url>
+		<snapshots>
+			<enabled>true</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-milestones</id>
+		<name>Spring Milestones</name>
+		<url>https://repo.spring.io/milestone</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+	<pluginRepository>
+		<id>spring-releases</id>
+		<name>Spring Releases</name>
+		<url>https://repo.spring.io/release</url>
+		<snapshots>
+			<enabled>false</enabled>
+		</snapshots>
+	</pluginRepository>
+</pluginRepositories>

+

Gradle.  +

buildscript {
+	repositories {
+		mavenCentral()
+		mavenLocal()
+		maven { url "https://repo.spring.io/snapshot" }
+		maven { url "https://repo.spring.io/milestone" }
+		maven { url "https://repo.spring.io/release" }
+	}

+

89.2 Publishing Stubs as JARs

The easiest approach would be to centralize the way stubs are kept. For example, you can +keep them as jars in a Maven repository.

[Tip]Tip

For both Maven and Gradle, the setup comes ready to work. However, you can customize +it if you want to.

Maven.  +

<!-- First disable the default jar setup in the properties section -->
+<!-- we don't want the verifier to do a jar for us -->
+<spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip>
+
+<!-- Next add the assembly plugin to your build -->
+<!-- we want the assembly plugin to generate the JAR -->
+<plugin>
+	<groupId>org.apache.maven.plugins</groupId>
+	<artifactId>maven-assembly-plugin</artifactId>
+	<executions>
+		<execution>
+			<id>stub</id>
+			<phase>prepare-package</phase>
+			<goals>
+				<goal>single</goal>
+			</goals>
+			<inherited>false</inherited>
+			<configuration>
+				<attach>true</attach>
+				<descriptors>
+					$../../../../src/assembly/stub.xml
+				</descriptors>
+			</configuration>
+		</execution>
+	</executions>
+</plugin>
+
+<!-- Finally setup your assembly. Below you can find the contents of src/main/assembly/stub.xml -->
+<assembly
+	xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	<id>stubs</id>
+	<formats>
+		<format>jar</format>
+	</formats>
+	<includeBaseDirectory>false</includeBaseDirectory>
+	<fileSets>
+		<fileSet>
+			<directory>src/main/java</directory>
+			<outputDirectory>/</outputDirectory>
+			<includes>
+				<include>**com/example/model/*.*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>${project.build.directory}/classes</directory>
+			<outputDirectory>/</outputDirectory>
+			<includes>
+				<include>**com/example/model/*.*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>${project.build.directory}/snippets/stubs</directory>
+			<outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/mappings</outputDirectory>
+			<includes>
+				<include>**/*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>$../../../../src/test/resources/contracts</directory>
+			<outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/contracts</outputDirectory>
+			<includes>
+				<include>**/*.groovy</include>
+			</includes>
+		</fileSet>
+	</fileSets>
+</assembly>

+

Gradle.  +

ext {
+	contractsDir = file("mappings")
+	stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/")
+}
+
+// Automatically added by plugin:
+// copyContracts - copies contracts to the output folder from which JAR will be created
+// verifierStubsJar - JAR with a provided stub suffix
+// the presented publication is also added by the plugin but you can modify it as you wish
+
+publishing {
+	publications {
+		stubs(MavenPublication) {
+			artifactId "${project.name}-stubs"
+			artifact verifierStubsJar
+		}
+	}
+}

+

89.3 Stub Runner Core

Runs stubs for service collaborators. Treating stubs as contracts of services allows to use stub-runner as an implementation of +Consumer Driven Contracts.

Stub Runner allows you to automatically download the stubs of the provided dependencies (or pick those from the classpath), start WireMock servers for them and feed them with proper stub definitions. +For messaging, special stub routes are defined.

89.3.1 Retrieving stubs

You can pick the following options of acquiring stubs

  • Aether based solution that downloads JARs with stubs from Artifactory / Nexus
  • Classpath scanning solution that searches classpath via pattern to retrieve stubs
  • Write your own implementation of the org.springframework.cloud.contract.stubrunner.StubDownloaderBuilder for full customization

The latter example is described in the Custom Stub Runner section.

Stub downloading

If you provide the stubrunner.repositoryRoot or stubrunner.workOffline flag will be set +to true then Stub Runner will connect to the given server and download the required jars. +It will then unpack the JAR to a temporary folder and reference those files in further +contract processing.

Example:

@AutoConfigureStubRunner(repositoryRoot="https://foo.bar", ids = "com.example:beer-api-producer:+:stubs:8095")

Classpath scanning

If you DON’T provide the stubrunner.repositoryRoot and stubrunner.workOffline flag will +be set to false (that’s the default) then classpath will get scanned. Let’s look at the +following example:

@AutoConfigureStubRunner(ids = {
+    "com.example:beer-api-producer:+:stubs:8095",
+    "com.example.foo:bar:1.0.0:superstubs:8096"
+})

If you’ve added the dependencies to your classpath

Maven.  +

<dependency>
+    <groupId>com.example</groupId>
+    <artifactId>beer-api-producer-restdocs</artifactId>
+    <classifier>stubs</classifier>
+    <version>0.0.1-SNAPSHOT</version>
+    <scope>test</scope>
+    <exclusions>
+        <exclusion>
+            <groupId>*</groupId>
+            <artifactId>*</artifactId>
+        </exclusion>
+    </exclusions>
+</dependency>
+<dependency>
+    <groupId>com.example.foo</groupId>
+    <artifactId>bar</artifactId>
+    <classifier>superstubs</classifier>
+    <version>1.0.0</version>
+    <scope>test</scope>
+    <exclusions>
+        <exclusion>
+            <groupId>*</groupId>
+            <artifactId>*</artifactId>
+        </exclusion>
+    </exclusions>
+</dependency>

+

Gradle.  +

testCompile("com.example:beer-api-producer-restdocs:0.0.1-SNAPSHOT:stubs") {
+    transitive = false
+}
+testCompile("com.example.foo:bar:1.0.0:superstubs") {
+    transitive = false
+}

+

Then the following locations on your classpath will get scanned. For com.example:beer-api-producer-restdocs

  • /META-INF/com.example/beer-api-producer-restdocs/*/.*
  • /contracts/com.example/beer-api-producer-restdocs/*/.*
  • /mappings/com.example/beer-api-producer-restdocs/*/.*

and com.example.foo:bar

  • /META-INF/com.example.foo/bar/*/.*
  • /contracts/com.example.foo/bar/*/.*
  • /mappings/com.example.foo/bar/*/.*
[Tip]Tip

As you can see you have to explicitly provide the group and artifact ids when packaging the +producer stubs.

The producer would setup the contracts like this:

└── src
+    └── test
+        └── resources
+            └── contracts
+                └── com.example
+                    └── beer-api-producer-restdocs
+                        └── nested
+                            └── contract3.groovy

To achieve proper stub packaging.

Or using the Maven assembly plugin or +Gradle Jar task you have to create the following +structure in your stubs jar.

└── META-INF
+    └── com.example
+        └── beer-api-producer-restdocs
+            └── 2.0.0
+                ├── contracts
+                │   └── nested
+                │       └── contract2.groovy
+                └── mappings
+                    └── mapping.json

By maintaining this structure classpath gets scanned and you can profit from the messaging / +HTTP stubs without the need to download artifacts.

89.3.2 Running stubs

Running using main app

You can set the following options to the main class:

-c, --classifier                Suffix for the jar containing stubs (e.
+                                  g. 'stubs' if the stub jar would
+                                  have a 'stubs' classifier for stubs:
+                                  foobar-stubs ). Defaults to 'stubs'
+                                  (default: stubs)
+--maxPort, --maxp <Integer>     Maximum port value to be assigned to
+                                  the WireMock instance. Defaults to
+                                  15000 (default: 15000)
+--minPort, --minp <Integer>     Minimum port value to be assigned to
+                                  the WireMock instance. Defaults to
+                                  10000 (default: 10000)
+-p, --password                  Password to user when connecting to
+                                  repository
+--phost, --proxyHost            Proxy host to use for repository
+                                  requests
+--pport, --proxyPort [Integer]  Proxy port to use for repository
+                                  requests
+-r, --root                      Location of a Jar containing server
+                                  where you keep your stubs (e.g. http:
+                                  //nexus.
+                                  net/content/repositories/repository)
+-s, --stubs                     Comma separated list of Ivy
+                                  representation of jars with stubs.
+                                  Eg. groupid:artifactid1,groupid2:
+                                  artifactid2:classifier
+-u, --username                  Username to user when connecting to
+                                  repository
+--wo, --workOffline             Switch to work offline. Defaults to
+                                  'false'

HTTP Stubs

Stubs are defined in JSON documents, whose syntax is defined in WireMock documentation

Example:

{
+    "request": {
+        "method": "GET",
+        "url": "/ping"
+    },
+    "response": {
+        "status": 200,
+        "body": "pong",
+        "headers": {
+            "Content-Type": "text/plain"
+        }
+    }
+}

Viewing registered mappings

Every stubbed collaborator exposes list of defined mappings under __/admin/ endpoint.

You can also use the mappingsOutputFolder property to dump the mappings to files. + For annotation based approach it would look like this

@AutoConfigureStubRunner(ids="a.b.c:loanIssuance,a.b.c:fraudDetectionServer",
+mappingsOutputFolder = "target/outputmappings/")

and for the JUnit approach like this:

@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule()
+			.repoRoot("http://some_url")
+			.downloadStub("a.b.c", "loanIssuance")
+			.downloadStub("a.b.c:fraudDetectionServer")
+			.withMappingsOutputFolder("target/outputmappings")

Then if you check out the folder target/outputmappings you would see the following structure

.
+├── fraudDetectionServer_13705
+└── loanIssuance_12255

That means that there were two stubs registered. fraudDetectionServer was registered at port 13705 +and loanIssuance at port 12255. If we take a look at one of the files we would see (for WireMock) +mappings available for the given server:

[{
+  "id" : "f9152eb9-bf77-4c38-8289-90be7d10d0d7",
+  "request" : {
+    "url" : "/name",
+    "method" : "GET"
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "fraudDetectionServer"
+  },
+  "uuid" : "f9152eb9-bf77-4c38-8289-90be7d10d0d7"
+},
+...
+]

Messaging Stubs

Depending on the provided Stub Runner dependency and the DSL the messaging routes are automatically set up.

89.4 Stub Runner JUnit Rule

Stub Runner comes with a JUnit rule thanks to which you can very easily download and run stubs for given group and artifact id:

@ClassRule public static StubRunnerRule rule = new StubRunnerRule()
+		.repoRoot(repoRoot())
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer");

After that rule gets executed Stub Runner connects to your Maven repository and for the given list of dependencies tries to:

  • download them
  • cache them locally
  • unzip them to a temporary folder
  • start a WireMock server for each Maven dependency on a random port from the provided range of ports / provided port
  • feed the WireMock server with all JSON files that are valid WireMock definitions
  • can also send messages (remember to pass an implementation of MessageVerifier interface)

Stub Runner uses Eclipse Aether mechanism to download the Maven dependencies. +Check their docs for more information.

Since the StubRunnerRule implements the StubFinder it allows you to find the started stubs:

package org.springframework.cloud.contract.stubrunner;
+
+import java.net.URL;
+import java.util.Collection;
+import java.util.Map;
+
+import org.springframework.cloud.contract.spec.Contract;
+
+public interface StubFinder extends StubTrigger {
+	/**
+	 * For the given groupId and artifactId tries to find the matching
+	 * URL of the running stub.
+	 *
+	 * @param groupId - might be null. In that case a search only via artifactId takes place
+	 * @return URL of a running stub or throws exception if not found
+	 */
+	URL findStubUrl(String groupId, String artifactId) throws StubNotFoundException;
+
+	/**
+	 * For the given Ivy notation {@code [groupId]:artifactId:[version]:[classifier]} tries to
+	 * find the matching URL of the running stub. You can also pass only {@code artifactId}.
+	 *
+	 * @param ivyNotation - Ivy representation of the Maven artifact
+	 * @return URL of a running stub or throws exception if not found
+	 */
+	URL findStubUrl(String ivyNotation) throws StubNotFoundException;
+
+	/**
+	 * Returns all running stubs
+	 */
+	RunningStubs findAllRunningStubs();
+
+	/**
+	 * Returns the list of Contracts
+	 */
+	Map<StubConfiguration, Collection<Contract>> getContracts();
+}

Example of usage in Spock tests:

@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule()
+		.repoRoot(StubRunnerRuleSpec.getResource("/m2repo/repository").toURI().toString())
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")
+		.withMappingsOutputFolder("target/outputmappingsforrule")
+
+
+def 'should start WireMock servers'() {
+	expect: 'WireMocks are running'
+		rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null
+		rule.findStubUrl('loanIssuance') != null
+		rule.findStubUrl('loanIssuance') == rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance')
+		rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null
+	and:
+		rule.findAllRunningStubs().isPresent('loanIssuance')
+		rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer')
+		rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer')
+	and: 'Stubs were registered'
+		"${rule.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
+		"${rule.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
+}
+
+def 'should output mappings to output folder'() {
+	when:
+		def url = rule.findStubUrl('fraudDetectionServer')
+	then:
+		new File("target/outputmappingsforrule", "fraudDetectionServer_${url.port}").exists()
+}

Example of usage in JUnit tests:

@Test
+public void should_start_wiremock_servers() throws Exception {
+	// expect: 'WireMocks are running'
+		then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")).isNotNull();
+		then(rule.findStubUrl("loanIssuance")).isNotNull();
+		then(rule.findStubUrl("loanIssuance")).isEqualTo(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance"));
+		then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isNotNull();
+	// and:
+		then(rule.findAllRunningStubs().isPresent("loanIssuance")).isTrue();
+		then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs", "fraudDetectionServer")).isTrue();
+		then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isTrue();
+	// and: 'Stubs were registered'
+		then(httpGet(rule.findStubUrl("loanIssuance").toString() + "/name")).isEqualTo("loanIssuance");
+		then(httpGet(rule.findStubUrl("fraudDetectionServer").toString() + "/name")).isEqualTo("fraudDetectionServer");
+}

Check the Common properties for JUnit and Spring for more information on how to apply global configuration of Stub Runner.

[Important]Important

To use the JUnit rule together with messaging you have to provide an implementation of the +MessageVerifier interface to the rule builder (e.g. rule.messageVerifier(new MyMessageVerifier())). +If you don’t do this then whenever you try to send a message an exception will be thrown.

89.4.1 Maven settings

The stub downloader honors Maven settings for a different local repository folder. +Authentication details for repositories and profiles are currently not taken into account, so you need to specify it using the properties mentioned above.

89.4.2 Providing fixed ports

You can also run your stubs on fixed ports. You can do it in two different ways. One is to pass it in the properties, and the other via fluent API of +JUnit rule.

89.4.3 Fluent API

When using the StubRunnerRule you can add a stub to download and then pass the port for the last downloaded stub.

@ClassRule public static StubRunnerRule rule = new StubRunnerRule()
+		.repoRoot(repoRoot())
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
+		.withPort(12345)
+		.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer:12346");

You can see that for this example the following test is valid:

then(rule.findStubUrl("loanIssuance")).isEqualTo(URI.create("http://localhost:12345").toURL());
+then(rule.findStubUrl("fraudDetectionServer")).isEqualTo(URI.create("http://localhost:12346").toURL());

89.4.4 Stub Runner with Spring

Sets up Spring configuration of the Stub Runner project.

By providing a list of stubs inside your configuration file the Stub Runner automatically downloads +and registers in WireMock the selected stubs.

If you want to find the URL of your stubbed dependency you can autowire the StubFinder interface and use +its methods as presented below:

@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
+@SpringBootTest(properties = [" stubrunner.cloud.enabled=false",
+		"stubrunner.camel.enabled=false",
+		'foo=${stubrunner.runningstubs.fraudDetectionServer.port}'])
+@AutoConfigureStubRunner(mappingsOutputFolder = "target/outputmappings/")
+@ActiveProfiles("test")
+class StubRunnerConfigurationSpec extends Specification {
+
+	@Autowired StubFinder stubFinder
+	@Autowired Environment environment
+	@Value('${foo}') Integer foo
+
+	@BeforeClass
+	@AfterClass
+	void setupProps() {
+		System.clearProperty("stubrunner.repository.root")
+		System.clearProperty("stubrunner.classifier")
+	}
+
+	def 'should start WireMock servers'() {
+		expect: 'WireMocks are running'
+			stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null
+			stubFinder.findStubUrl('loanIssuance') != null
+			stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance')
+			stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance')
+			stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs')
+			stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null
+		and:
+			stubFinder.findAllRunningStubs().isPresent('loanIssuance')
+			stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer')
+			stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer')
+		and: 'Stubs were registered'
+			"${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
+			"${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
+	}
+
+	def 'should throw an exception when stub is not found'() {
+		when:
+			stubFinder.findStubUrl('nonExistingService')
+		then:
+			thrown(StubNotFoundException)
+		when:
+			stubFinder.findStubUrl('nonExistingGroupId', 'nonExistingArtifactId')
+		then:
+			thrown(StubNotFoundException)
+	}
+
+	def 'should register started servers as environment variables'() {
+		expect:
+			environment.getProperty("stubrunner.runningstubs.loanIssuance.port") != null
+			stubFinder.findAllRunningStubs().getPort("loanIssuance") == (environment.getProperty("stubrunner.runningstubs.loanIssuance.port") as Integer)
+		and:
+			environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") != null
+			stubFinder.findAllRunningStubs().getPort("fraudDetectionServer") == (environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") as Integer)
+	}
+
+	def 'should be able to interpolate a running stub in the passed test property'() {
+		given:
+			int fraudPort = stubFinder.findAllRunningStubs().getPort("fraudDetectionServer")
+		expect:
+			fraudPort > 0
+			environment.getProperty("foo", Integer) == fraudPort
+			foo == fraudPort
+	}
+
+	def 'should dump all mappings to a file'() {
+		when:
+			def url = stubFinder.findStubUrl("fraudDetectionServer")
+		then:
+			new File("target/outputmappings/", "fraudDetectionServer_${url.port}").exists()
+	}
+
+	@Configuration
+	@EnableAutoConfiguration
+	static class Config {}
+}

for the following configuration file:

stubrunner:
+  repositoryRoot: classpath:m2repo/repository/
+  ids:
+    - org.springframework.cloud.contract.verifier.stubs:loanIssuance
+    - org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer
+    - org.springframework.cloud.contract.verifier.stubs:bootService

Instead of using the properties you can also use the properties inside the @AutoConfigureStubRunner. +Below you can find an example of achieving the same result by setting values on the annotation.

@AutoConfigureStubRunner(
+		ids = ["org.springframework.cloud.contract.verifier.stubs:loanIssuance",
+		"org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer",
+		"org.springframework.cloud.contract.verifier.stubs:bootService"],
+		repositoryRoot = "classpath:m2repo/repository/")

Stub Runner Spring registers environment variables in the following manner +for every registered WireMock server. Example for Stub Runner ids + com.example:foo, com.example:bar.

  • stubrunner.runningstubs.foo.port
  • stubrunner.runningstubs.bar.port

Which you can reference in your code.

89.5 Stub Runner Spring Cloud

Stub Runner can integrate with Spring Cloud.

For real life examples you can check the

89.5.1 Stubbing Service Discovery

The most important feature of Stub Runner Spring Cloud is the fact that it’s stubbing

  • DiscoveryClient
  • Ribbon ServerList

that means that regardless of the fact whether you’re using Zookeeper, Consul, Eureka or anything else, you don’t need that in your tests. +We’re starting WireMock instances of your dependencies and we’re telling your application whenever you’re using Feign, load balanced RestTemplate +or DiscoveryClient directly, to call those stubbed servers instead of calling the real Service Discovery tool.

For example this test will pass

def 'should make service discovery work'() {
+	expect: 'WireMocks are running'
+		"${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
+		"${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
+	and: 'Stubs can be reached via load service discovery'
+		restTemplate.getForObject('http://loanIssuance/name', String) == 'loanIssuance'
+		restTemplate.getForObject('http://someNameThatShouldMapFraudDetectionServer/name', String) == 'fraudDetectionServer'
+}

for the following configuration file

stubrunner:
+  idsToServiceIds:
+    ivyNotation: someValueInsideYourCode
+    fraudDetectionServer: someNameThatShouldMapFraudDetectionServer

Test profiles and service discovery

In your integration tests you typically don’t want to call neither a discovery service (e.g. Eureka) +or Config Server. That’s why you create an additional test configuration in which you want to disable +these features.

Due to certain limitations of spring-cloud-commons to achieve this you have disable these properties +via a static block like presented below (example for Eureka)

    //Hack to work around https://github.com/spring-cloud/spring-cloud-commons/issues/156
+    static {
+        System.setProperty("eureka.client.enabled", "false");
+        System.setProperty("spring.cloud.config.failFast", "false");
+    }

89.5.2 Additional Configuration

You can match the artifactId of the stub with the name of your app by using the stubrunner.idsToServiceIds: map. +You can disable Stub Runner Ribbon support by providing: stubrunner.cloud.ribbon.enabled equal to false +You can disable Stub Runner support by providing: stubrunner.cloud.enabled equal to false

[Tip]Tip

By default all service discovery will be stubbed. That means that regardless of the fact if you have +an existing DiscoveryClient its results will be ignored. However, if you want to reuse it, just set + stubrunner.cloud.delegate.enabled to true and then your existing DiscoveryClient results will be + merged with the stubbed ones.

The default Maven configuration used by Stub Runner can be tweaked either +via the following system properties or environment variables

  • maven.repo.local - path to the custom maven local repository location
  • org.apache.maven.user-settings - path to custom maven user settings location
  • org.apache.maven.global-settings - path to maven global settings location

89.6 Stub Runner Boot Application

Spring Cloud Contract Stub Runner Boot is a Spring Boot application that exposes REST endpoints to +trigger the messaging labels and to access started WireMock servers.

One of the use-cases is to run some smoke (end to end) tests on a deployed application. +You can check out the Spring Cloud Pipelines +project for more information.

89.6.1 How to use it?

Stub Runner Server

Just add the

compile "org.springframework.cloud:spring-cloud-starter-stub-runner"

Annotate a class with @EnableStubRunnerServer, build a fat-jar and you’re ready to go!

For the properties check the Stub Runner Spring section.

Stub Runner Server Fat Jar

You can download a standalone JAR from Maven (for example, for version 1.2.3.RELEASE), as follows:

$ wget -O stub-runner.jar 'https://search.maven.org/remote_content?g=org.springframework.cloud&a=spring-cloud-contract-stub-runner-boot&v=1.2.3.RELEASE'
+$ java -jar stub-runner.jar --stubrunner.ids=... --stubrunner.repositoryRoot=...

Spring Cloud CLI

Starting from 1.4.0.RELEASE version of the Spring Cloud CLI +project you can start Stub Runner Boot by executing spring cloud stubrunner.

In order to pass the configuration just create a stubrunner.yml file in the current working directory +or a subdirectory called config or in ~/.spring-cloud. The file could look like this +(example for running stubs installed locally)

stubrunner.yml.  +

stubrunner:
+  workOffline: true
+  ids:
+    - com.example:beer-api-producer:+:9876

+

and then just call spring cloud stubrunner from your terminal window to start +the Stub Runner server. It will be available at port 8750.

89.6.2 Endpoints

HTTP

  • GET /stubs - returns a list of all running stubs in ivy:integer notation
  • GET /stubs/{ivy} - returns a port for the given ivy notation (when calling the endpoint ivy can also be artifactId only)

Messaging

For Messaging

  • GET /triggers - returns a list of all running labels in ivy : [ label1, label2 …​] notation
  • POST /triggers/{label} - executes a trigger with label
  • POST /triggers/{ivy}/{label} - executes a trigger with label for the given ivy notation (when calling the endpoint ivy can also be artifactId only)

89.6.3 Example

@ContextConfiguration(classes = StubRunnerBoot, loader = SpringBootContextLoader)
+@SpringBootTest(properties = "spring.cloud.zookeeper.enabled=false")
+@ActiveProfiles("test")
+class StubRunnerBootSpec extends Specification {
+
+	@Autowired StubRunning stubRunning
+
+	def setup() {
+		RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning),
+				new TriggerController(stubRunning))
+	}
+
+	def 'should return a list of running stub servers in "full ivy:port" notation'() {
+		when:
+			String response = RestAssuredMockMvc.get('/stubs').body.asString()
+		then:
+			def root = new JsonSlurper().parseText(response)
+			root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs' instanceof Integer
+	}
+
+	def 'should return a port on which a [#stubId] stub is running'() {
+		when:
+			def response = RestAssuredMockMvc.get("/stubs/${stubId}")
+		then:
+			response.statusCode == 200
+			response.body.as(Integer) > 0
+		where:
+			stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:+:stubs',
+					   'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs',
+					   'org.springframework.cloud.contract.verifier.stubs:bootService:+',
+					   'org.springframework.cloud.contract.verifier.stubs:bootService',
+					   'bootService']
+	}
+
+	def 'should return 404 when missing stub was called'() {
+		when:
+			def response = RestAssuredMockMvc.get("/stubs/a:b:c:d")
+		then:
+			response.statusCode == 404
+	}
+
+	def 'should return a list of messaging labels that can be triggered when version and classifier are passed'() {
+		when:
+			String response = RestAssuredMockMvc.get('/triggers').body.asString()
+		then:
+			def root = new JsonSlurper().parseText(response)
+			root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs'?.containsAll(["delete_book","return_book_1","return_book_2"])
+	}
+
+	def 'should trigger a messaging label'() {
+		given:
+			StubRunning stubRunning = Mock()
+			RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning))
+		when:
+			def response = RestAssuredMockMvc.post("/triggers/delete_book")
+		then:
+			response.statusCode == 200
+		and:
+			1 * stubRunning.trigger('delete_book')
+	}
+
+	def 'should trigger a messaging label for a stub with [#stubId] ivy notation'() {
+		given:
+			StubRunning stubRunning = Mock()
+			RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning))
+		when:
+			def response = RestAssuredMockMvc.post("/triggers/$stubId/delete_book")
+		then:
+			response.statusCode == 200
+		and:
+			1 * stubRunning.trigger(stubId, 'delete_book')
+		where:
+			stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:stubs', 'org.springframework.cloud.contract.verifier.stubs:bootService', 'bootService']
+	}
+
+	def 'should throw exception when trigger is missing'() {
+		when:
+			RestAssuredMockMvc.post("/triggers/missing_label")
+		then:
+			Exception e = thrown(Exception)
+			e.message.contains("Exception occurred while trying to return [missing_label] label.")
+			e.message.contains("Available labels are")
+			e.message.contains("org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs=[]")
+			e.message.contains("org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs=")
+	}
+
+}

89.6.4 Stub Runner Boot with Service Discovery

One of the possibilities of using Stub Runner Boot is to use it as a feed of stubs for "smoke-tests". What does it mean? + Let’s assume that you don’t want to deploy 50 microservice to a test environment in order + to check if your application is working fine. You’ve already executed a suite of tests during the build process + but you would also like to ensure that the packaging of your application is fine. What you can do + is to deploy your application to an environment, start it and run a couple of tests on it to see if + it’s working fine. We can call those tests smoke-tests since their idea is to check only a handful + of testing scenarios.

The problem with this approach is such that if you’re doing microservices most likely you’re + using a service discovery tool. Stub Runner Boot allows you to solve this issue by starting the + required stubs and register them in a service discovery tool. Let’s take a look at an example of + such a setup with Eureka. Let’s assume that Eureka was already running.

@SpringBootApplication
+@EnableStubRunnerServer
+@EnableEurekaClient
+@AutoConfigureStubRunner
+public class StubRunnerBootEurekaExample {
+
+	public static void main(String[] args) {
+		SpringApplication.run(StubRunnerBootEurekaExample.class, args);
+	}
+
+}

As you can see we want to start a Stub Runner Boot server @EnableStubRunnerServer, enable Eureka client @EnableEurekaClient +and we want to have the stub runner feature turned on @AutoConfigureStubRunner.

Now let’s assume that we want to start this application so that the stubs get automatically registered. + We can do it by running the app java -jar ${SYSTEM_PROPS} stub-runner-boot-eureka-example.jar where + ${SYSTEM_PROPS} would contain the following list of properties

-Dstubrunner.repositoryRoot=https://repo.spring.io/snapshot (1)
+-Dstubrunner.cloud.stubbed.discovery.enabled=false (2)
+-Dstubrunner.ids=org.springframework.cloud.contract.verifier.stubs:loanIssuance,org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer,org.springframework.cloud.contract.verifier.stubs:bootService (3)
+-Dstubrunner.idsToServiceIds.fraudDetectionServer=someNameThatShouldMapFraudDetectionServer (4)
+
+(1) - we tell Stub Runner where all the stubs reside
+(2) - we don't want the default behaviour where the discovery service is stubbed. That's why the stub registration will be picked
+(3) - we provide a list of stubs to download
+(4) - we provide a list of artifactId to serviceId mapping

That way your deployed application can send requests to started WireMock servers via the service +discovery. Most likely points 1-3 could be set by default in application.yml cause they are not +likely to change. That way you can provide only the list of stubs to download whenever you start +the Stub Runner Boot.

89.7 Stubs Per Consumer

There are cases in which 2 consumers of the same endpoint want to have 2 different responses.

[Tip]Tip

This approach also allows you to immediately know which consumer is using which part of your API. +You can remove part of a response that your API produces and you can see which of your autogenerated tests +fails. If none fails then you can safely delete that part of the response cause nobody is using it.

Let’s look at the following example for contract defined for the producer called producer. +There are 2 consumers: foo-consumer and bar-consumer.

Consumer foo-service

request {
+   url '/foo'
+   method GET()
+}
+response {
+    status 200
+    body(
+       foo: "foo"
+    }
+}

Consumer bar-service

request {
+   url '/foo'
+   method GET()
+}
+response {
+    status 200
+    body(
+       bar: "bar"
+    }
+}

You can’t produce for the same request 2 different responses. That’s why you can properly package the +contracts and then profit from the stubsPerConsumer feature.

On the producer side the consumers can have a folder that contains contracts related only to them. +By setting the stubrunner.stubs-per-consumer flag to true we no longer register all stubs but only those that +correspond to the consumer application’s name. In other words we’ll scan the path of every stub and +if it contains the subfolder with name of the consumer in the path only then will it get registered.

On the foo producer side the contracts would look like this

.
+└── contracts
+    ├── bar-consumer
+    │   ├── bookReturnedForBar.groovy
+    │   └── shouldCallBar.groovy
+    └── foo-consumer
+        ├── bookReturnedForFoo.groovy
+        └── shouldCallFoo.groovy

Being the bar-consumer consumer you can either set the spring.application.name or the stubrunner.consumer-name to bar-consumer +Or set the test as follows:

@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
+@SpringBootTest(properties = ["spring.application.name=bar-consumer"])
+@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers",
+		repositoryRoot = "classpath:m2repo/repository/",
+		stubsPerConsumer = true)
+class StubRunnerStubsPerConsumerSpec extends Specification {
+...
+}

Then only the stubs registered under a path that contains the bar-consumer in its name (i.e. those from the +src/test/resources/contracts/bar-consumer/some/contracts/…​ folder) will be allowed to be referenced.

Or set the consumer name explicitly

@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
+@SpringBootTest
+@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers",
+		repositoryRoot = "classpath:m2repo/repository/",
+		consumerName = "foo-consumer",
+		stubsPerConsumer = true)
+class StubRunnerStubsPerConsumerWithConsumerNameSpec extends Specification {
+...
+}

Then only the stubs registered under a path that contains the foo-consumer in its name (i.e. those from the +src/test/resources/contracts/foo-consumer/some/contracts/…​ folder) will be allowed to be referenced.

You can check out issue 224 for more +information about the reasons behind this change.

89.8 Common

This section briefly describes common properties, including:

89.8.1 Common Properties for JUnit and Spring

You can set repetitive properties by using system properties or Spring configuration +properties. Here are their names with their default values:

Property nameDefault valueDescription

stubrunner.minPort

10000

Minimum value of a port for a started WireMock with stubs.

stubrunner.maxPort

15000

Maximum value of a port for a started WireMock with stubs.

stubrunner.repositoryRoot

 

Maven repo URL. If blank, then call the local maven repo.

stubrunner.classifier

stubs

Default classifier for the stub artifacts.

stubrunner.workOffline

false

If true, then do not contact any remote repositories to +download stubs.

stubrunner.ids

 

Array of Ivy notation stubs to download.

stubrunner.username

 

Optional username to access the tool that stores the JARs with +stubs.

stubrunner.password

 

Optional password to access the tool that stores the JARs with +stubs.

stubrunner.stubsPerConsumer

false

Set to true if you want to use different stubs for +each consumer instead of registering all stubs for every consumer.

stubrunner.consumerName

 

If you want to use a stub for each consumer and want to +override the consumer name just change this value.

89.8.2 Stub Runner Stubs IDs

You can provide the stubs to download via the stubrunner.ids system property. They +follow this pattern:

groupId:artifactId:version:classifier:port

Note that version, classifier and port are optional.

  • If you do not provide the port, a random one will be picked.
  • If you do not provide the classifier, the default is used. (Note that you can +pass an empty classifier this way: groupId:artifactId:version:).
  • If you do not provide the version, then the + will be passed and the latest one is +downloaded.

port means the port of the WireMock server.

[Important]Important

Starting with version 1.0.4, you can provide a range of versions that you +would like the Stub Runner to take into consideration. You can read more about the +Aether versioning +ranges here.

89.9 Stub Runner Docker

We’re publishing a spring-cloud/spring-cloud-contract-stub-runner Docker image +that will start the standalone version of Stub Runner.

If you want to learn more about the basics of Maven, artifact ids, +group ids, classifiers and Artifact Managers, just click here Section 87.6, “Docker Project”.

89.9.1 How to use it

Just execute the docker image. You can pass any of the Section 89.8.1, “Common Properties for JUnit and Spring” +as environment variables. The convention is that all the +letters should be upper case. The camel case notation should +and the dot (.) should be separated via underscore (_). E.g. + the stubrunner.repositoryRoot property should be represented + as a STUBRUNNER_REPOSITORY_ROOT environment variable.

89.9.2 Example of client side usage in a non JVM project

We’d like to use the stubs created in this Section 87.6.4, “Server side (nodejs)” step. +Let’s assume that we want to run the stubs on port 9876. The NodeJS code +is available here:

$ git clone https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs
+$ cd bookstore

Let’s run the Stub Runner Boot application with the stubs.

# Provide the Spring Cloud Contract Docker version
+$ SC_CONTRACT_DOCKER_VERSION="..."
+# The IP at which the app is running and Docker container can reach it
+$ APP_IP="192.168.0.100"
+# Spring Cloud Contract Stub Runner properties
+$ STUBRUNNER_PORT="8083"
+# Stub coordinates 'groupId:artifactId:version:classifier:port'
+$ STUBRUNNER_IDS="com.example:bookstore:0.0.1.RELEASE:stubs:9876"
+$ STUBRUNNER_REPOSITORY_ROOT="http://${APP_IP}:8081/artifactory/libs-release-local"
+# Run the docker with Stub Runner Boot
+$ docker run  --rm -e "STUBRUNNER_IDS=${STUBRUNNER_IDS}" -e "STUBRUNNER_REPOSITORY_ROOT=${STUBRUNNER_REPOSITORY_ROOT}" -p "${STUBRUNNER_PORT}:${STUBRUNNER_PORT}" -p "9876:9876" springcloud/spring-cloud-contract-stub-runner:"${SC_CONTRACT_DOCKER_VERSION}"

What’s happening is that

  • a standalone Stub Runner application got started
  • it downloaded the stub with coordinates com.example:bookstore:0.0.1.RELEASE:stubs on port 9876
  • it got downloaded from Artifactory running at http://192.168.0.100:8081/artifactory/libs-release-local
  • after a while Stub Runner will be running on port 8083
  • and the stubs will be running at port 9876

On the server side we built a stateful stub. Let’s use curl to assert +that the stubs are setup properly.

# let's execute the first request (no response is returned)
+$ curl -H "Content-Type:application/json" -X POST --data '{ "title" : "Title", "genre" : "Genre", "description" : "Description", "author" : "Author", "publisher" : "Publisher", "pages" : 100, "image_url" : "https://d213dhlpdb53mu.cloudfront.net/assets/pivotal-square-logo-41418bd391196c3022f3cd9f3959b3f6d7764c47873d858583384e759c7db435.svg", "buy_url" : "https://pivotal.io" }' http://localhost:9876/api/books
+# Now time for the second request
+$ curl -X GET http://localhost:9876/api/books
+# You will receive contents of the JSON

90. Stub Runner for Messaging

Stub Runner can run the published stubs in memory. It can integrate with the following +frameworks:

  • Spring Integration
  • Spring Cloud Stream
  • Apache Camel
  • Spring AMQP

It also provides entry points to integrate with any other solution on the market.

[Important]Important

If you have multiple frameworks on the classpath Stub Runner will need to +define which one should be used. Let’s assume that you have both AMQP, Spring Cloud Stream and Spring Integration +on the classpath. Then you need to set stubrunner.stream.enabled=false and stubrunner.integration.enabled=false. +That way the only remaining framework is Spring AMQP.

90.1 Stub triggering

To trigger a message, use the StubTrigger interface:

package org.springframework.cloud.contract.stubrunner;
+
+import java.util.Collection;
+import java.util.Map;
+
+public interface StubTrigger {
+
+	/**
+	 * Triggers an event by a given label for a given {@code groupid:artifactid} notation. You can use only {@code artifactId} too.
+	 *
+	 * Feature related to messaging.
+	 *
+	 * @return true - if managed to run a trigger
+	 */
+	boolean trigger(String ivyNotation, String labelName);
+
+	/**
+	 * Triggers an event by a given label.
+	 *
+	 * Feature related to messaging.
+	 *
+	 * @return true - if managed to run a trigger
+	 */
+	boolean trigger(String labelName);
+
+	/**
+	 * Triggers all possible events.
+	 *
+	 * Feature related to messaging.
+	 *
+	 * @return true - if managed to run a trigger
+	 */
+	boolean trigger();
+
+	/**
+	 * Returns a mapping of ivy notation of a dependency to all the labels it has.
+	 *
+	 * Feature related to messaging.
+	 */
+	Map<String, Collection<String>> labels();
+}

For convenience, the StubFinder interface extends StubTrigger, so you only need one +or the other in your tests.

StubTrigger gives you the following options to trigger a message:

90.1.1 Trigger by Label

stubFinder.trigger('return_book_1')

90.1.2 Trigger by Group and Artifact Ids

stubFinder.trigger('org.springframework.cloud.contract.verifier.stubs:camelService', 'return_book_1')

90.1.3 Trigger by Artifact Ids

stubFinder.trigger('camelService', 'return_book_1')

90.1.4 Trigger All Messages

stubFinder.trigger()

90.2 Stub Runner Camel

Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Apache Camel. For the provided artifacts, it automatically downloads the +stubs and registers the required routes.

90.2.1 Adding the Runner to the Project

You can have both Apache Camel and Spring Cloud Contract Stub Runner on the classpath. +Remember to annotate your test class with @AutoConfigureStubRunner.

90.2.2 Disabling the functionality

If you need to disable this functionality, set the stubrunner.camel.enabled=false +property.

Assume that you have the following Maven repository with deployed stubs for the +camelService application:

└── .m2
+    └── repository
+        └── io
+            └── codearte
+                └── accurest
+                    └── stubs
+                        └── camelService
+                            ├── 0.0.1-SNAPSHOT
+                            │   ├── camelService-0.0.1-SNAPSHOT.pom
+                            │   ├── camelService-0.0.1-SNAPSHOT-stubs.jar
+                            │   └── maven-metadata-local.xml
+                            └── maven-metadata-local.xml

Further assume that the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── repository
+    ├── accurest
+    │   ├── bookDeleted.groovy
+    │   ├── bookReturned1.groovy
+    │   └── bookReturned2.groovy
+    └── mappings

Consider the following contracts (numbered 1):

Contract.make {
+	label 'return_book_1'
+	input {
+		triggeredBy('bookReturnedTriggered()')
+	}
+	outputMessage {
+		sentTo('jms:output')
+		body('''{ "bookName" : "foo" }''')
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

Now consider 2

Contract.make {
+	label 'return_book_2'
+	input {
+		messageFrom('jms:input')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('jms:output')
+		body([
+				bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

These examples lend themselves to three scenarios:

Scenario 1 (no input message)

To trigger a message via the return_book_1 label, use the StubTigger interface, as +follows:

stubFinder.trigger('return_book_1')

To listen to the output of the message sent to jms:output:

Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000)

The received message passes the following assertions:

receivedMessage != null
+assertThatBodyContainsBookNameFoo(receivedMessage.in.body)
+receivedMessage.in.headers.get('BOOK-NAME') == 'foo'

Scenario 2 (output triggered by input)

Since the route is set for you, you can send a message to the jms:output +destination:

camelContext.createProducerTemplate().sendBodyAndHeaders('jms:input', new BookReturned('foo'), [sample: 'header'])

You can listen to the output of the message sent to jms:output:

Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000)

The received message passes the following assertions:

receivedMessage != null
+assertThatBodyContainsBookNameFoo(receivedMessage.in.body)
+receivedMessage.in.headers.get('BOOK-NAME') == 'foo'

Scenario 3 (input with no output)

Since the route is set for you, you can send a message to the jms:output +destination:

camelContext.createProducerTemplate().sendBodyAndHeaders('jms:delete', new BookReturned('foo'), [sample: 'header'])

90.3 Stub Runner Integration

Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Spring Integration. For the provided artifacts, it automatically downloads +the stubs and registers the required routes.

90.3.1 Adding the Runner to the Project

You can have both Spring Integration and Spring Cloud Contract Stub Runner on the +classpath. Remember to annotate your test class with @AutoConfigureStubRunner.

90.3.2 Disabling the functionality

If you need to disable this functionality, set the +stubrunner.integration.enabled=false property.

Assume that you have the following Maven repository with deployed stubs for the +integrationService application:

└── .m2
+    └── repository
+        └── io
+            └── codearte
+                └── accurest
+                    └── stubs
+                        └── integrationService
+                            ├── 0.0.1-SNAPSHOT
+                            │   ├── integrationService-0.0.1-SNAPSHOT.pom
+                            │   ├── integrationService-0.0.1-SNAPSHOT-stubs.jar
+                            │   └── maven-metadata-local.xml
+                            └── maven-metadata-local.xml

Further assume the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── repository
+    ├── accurest
+    │   ├── bookDeleted.groovy
+    │   ├── bookReturned1.groovy
+    │   └── bookReturned2.groovy
+    └── mappings

Consider the following contracts (numbered 1):

Contract.make {
+	label 'return_book_1'
+	input {
+		triggeredBy('bookReturnedTriggered()')
+	}
+	outputMessage {
+		sentTo('output')
+		body('''{ "bookName" : "foo" }''')
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

Now consider 2:

Contract.make {
+	label 'return_book_2'
+	input {
+		messageFrom('input')
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('output')
+		body([
+				bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

and the following Spring Integration Route:

<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/integration"
+			 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+			 xmlns:beans="http://www.springframework.org/schema/beans"
+			 xsi:schemaLocation="http://www.springframework.org/schema/beans
+			https://www.springframework.org/schema/beans/spring-beans.xsd
+			http://www.springframework.org/schema/integration
+			https://www.springframework.org/schema/integration/spring-integration.xsd">
+
+
+	<!-- REQUIRED FOR TESTING -->
+	<bridge input-channel="output"
+			output-channel="outputTest"/>
+
+	<channel id="outputTest">
+		<queue/>
+	</channel>
+
+</beans:beans>

These examples lend themselves to three scenarios:

Scenario 1 (no input message)

To trigger a message via the return_book_1 label, use the StubTigger interface, as +follows:

stubFinder.trigger('return_book_1')

To listen to the output of the message sent to output:

Message<?> receivedMessage = messaging.receive('outputTest')

The received message would pass the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 2 (output triggered by input)

Since the route is set for you, you can send a message to the output +destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'input')

To listen to the output of the message sent to output:

Message<?> receivedMessage = messaging.receive('outputTest')

The received message passes the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 3 (input with no output)

Since the route is set for you, you can send a message to the input destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete')

90.4 Stub Runner Stream

Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Spring Stream. For the provided artifacts, it automatically downloads the +stubs and registers the required routes.

[Warning]Warning

If Stub Runner’s integration with Stream the messageFrom or sentTo Strings +are resolved first as a destination of a channel and no such destination exists, the +destination is resolved as a channel name.

[Important]Important

If you want to use Spring Cloud Stream remember, to add a dependency on +org.springframework.cloud:spring-cloud-stream-test-support.

Maven.  +

<dependency>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-stream-test-support</artifactId>
+    <scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile "org.springframework.cloud:spring-cloud-stream-test-support"

+

90.4.1 Adding the Runner to the Project

You can have both Spring Cloud Stream and Spring Cloud Contract Stub Runner on the +classpath. Remember to annotate your test class with @AutoConfigureStubRunner.

90.4.2 Disabling the functionality

If you need to disable this functionality, set the stubrunner.stream.enabled=false +property.

Assume that you have the following Maven repository with a deployed stubs for the +streamService application:

└── .m2
+    └── repository
+        └── io
+            └── codearte
+                └── accurest
+                    └── stubs
+                        └── streamService
+                            ├── 0.0.1-SNAPSHOT
+                            │   ├── streamService-0.0.1-SNAPSHOT.pom
+                            │   ├── streamService-0.0.1-SNAPSHOT-stubs.jar
+                            │   └── maven-metadata-local.xml
+                            └── maven-metadata-local.xml

Further assume the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── repository
+    ├── accurest
+    │   ├── bookDeleted.groovy
+    │   ├── bookReturned1.groovy
+    │   └── bookReturned2.groovy
+    └── mappings

Consider the following contracts (numbered 1):

Contract.make {
+	label 'return_book_1'
+	input { triggeredBy('bookReturnedTriggered()') }
+	outputMessage {
+		sentTo('returnBook')
+		body('''{ "bookName" : "foo" }''')
+		headers { header('BOOK-NAME', 'foo') }
+	}
+}

Now consider 2:

Contract.make {
+	label 'return_book_2'
+	input {
+		messageFrom('bookStorage')
+		messageBody([
+			bookName: 'foo'
+		])
+		messageHeaders { header('sample', 'header') }
+	}
+	outputMessage {
+		sentTo('returnBook')
+		body([
+			bookName: 'foo'
+		])
+		headers { header('BOOK-NAME', 'foo') }
+	}
+}

Now consider the following Spring configuration:

stubrunner.repositoryRoot: classpath:m2repo/repository/
+stubrunner.ids: org.springframework.cloud.contract.verifier.stubs:streamService:0.0.1-SNAPSHOT:stubs
+
+spring:
+  cloud:
+    stream:
+      bindings:
+        output:
+          destination: returnBook
+        input:
+          destination: bookStorage
+
+server:
+  port: 0
+
+debug: true

These examples lend themselves to three scenarios:

Scenario 1 (no input message)

To trigger a message via the return_book_1 label, use the StubTrigger interface as +follows:

stubFinder.trigger('return_book_1')

To listen to the output of the message sent to a channel whose destination is +returnBook:

Message<?> receivedMessage = messaging.receive('returnBook')

The received message passes the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 2 (output triggered by input)

Since the route is set for you, you can send a message to the bookStorage +destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'bookStorage')

To listen to the output of the message sent to returnBook:

Message<?> receivedMessage = messaging.receive('returnBook')

The received message passes the following assertions:

receivedMessage != null
+assertJsons(receivedMessage.payload)
+receivedMessage.headers.get('BOOK-NAME') == 'foo'

Scenario 3 (input with no output)

Since the route is set for you, you can send a message to the output +destination:

messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete')

90.5 Stub Runner Spring AMQP

Spring Cloud Contract Verifier Stub Runner’s messaging module provides an easy way to +integrate with Spring AMQP’s Rabbit Template. For the provided artifacts, it +automatically downloads the stubs and registers the required routes.

The integration tries to work standalone (that is, without interaction with a running +RabbitMQ message broker). It expects a RabbitTemplate on the application context and +uses it as a spring boot test named @SpyBean. As a result, it can use the mockito spy +functionality to verify and inspect messages sent by the application.

On the message consumer side, the stub runner considers all @RabbitListener annotated +endpoints and all SimpleMessageListenerContainer objects on the application context.

As messages are usually sent to exchanges in AMQP, the message contract contains the +exchange name as the destination. Message listeners on the other side are bound to +queues. Bindings connect an exchange to a queue. If message contracts are triggered, the +Spring AMQP stub runner integration looks for bindings on the application context that +match this exchange. Then it collects the queues from the Spring exchanges and tries to +find message listeners bound to these queues. The message is triggered for all matching +message listeners.

90.5.1 Adding the Runner to the Project

You can have both Spring AMQP and Spring Cloud Contract Stub Runner on the classpath and +set the property stubrunner.amqp.enabled=true. Remember to annotate your test class +with @AutoConfigureStubRunner.

[Important]Important

If you already have Stream and Integration on the classpath, you need +to disable them explicitly by setting the stubrunner.stream.enabled=false and +stubrunner.integration.enabled=false properties.

Assume that you have the following Maven repository with a deployed stubs for the +spring-cloud-contract-amqp-test application.

└── .m2
+    └── repository
+        └── com
+            └── example
+                └── spring-cloud-contract-amqp-test
+                    ├── 0.4.0-SNAPSHOT
+                    │   ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT.pom
+                    │   ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT-stubs.jar
+                    │   └── maven-metadata-local.xml
+                    └── maven-metadata-local.xml

Further assume that the stubs contain the following structure:

├── META-INF
+│   └── MANIFEST.MF
+└── contracts
+    └── shouldProduceValidPersonData.groovy

Consider the following contract:

Contract.make {
+    // Human readable description
+    description 'Should produce valid person data'
+    // Label by means of which the output message can be triggered
+    label 'contract-test.person.created.event'
+    // input to the contract
+    input {
+        // the contract will be triggered by a method
+        triggeredBy('createPerson()')
+    }
+    // output message of the contract
+    outputMessage {
+        // destination to which the output message will be sent
+        sentTo 'contract-test.exchange'
+        headers {
+            header('contentType': 'application/json')
+            header('__TypeId__': 'org.springframework.cloud.contract.stubrunner.messaging.amqp.Person')
+        }
+        // the body of the output message
+        body ([
+                id: $(consumer(9), producer(regex("[0-9]+"))),
+                name: "me"
+        ])
+    }
+}

Now consider the following Spring configuration:

stubrunner:
+  repositoryRoot: classpath:m2repo/repository/
+  ids: org.springframework.cloud.contract.verifier.stubs.amqp:spring-cloud-contract-amqp-test:0.4.0-SNAPSHOT:stubs
+  amqp:
+    enabled: true
+server:
+  port: 0

Triggering the message

To trigger a message using the contract above, use the StubTrigger interface as +follows:

stubTrigger.trigger("contract-test.person.created.event")

The message has a destination of contract-test.exchange, so the Spring AMQP stub runner +integration looks for bindings related to this exchange.

@Bean
+public Binding binding() {
+	return BindingBuilder.bind(new Queue("test.queue")).to(new DirectExchange("contract-test.exchange")).with("#");
+}

The binding definition binds the queue test.queue. As a result, the following listener +definition is matched and invoked with the contract message.

@Bean
+public SimpleMessageListenerContainer simpleMessageListenerContainer(ConnectionFactory connectionFactory,
+																		MessageListenerAdapter listenerAdapter) {
+	SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
+	container.setConnectionFactory(connectionFactory);
+	container.setQueueNames("test.queue");
+	container.setMessageListener(listenerAdapter);
+
+	return container;
+}

Also, the following annotated listener matches and is invoked:

@RabbitListener(bindings = @QueueBinding(
+		value = @Queue(value = "test.queue"),
+		exchange = @Exchange(value = "contract-test.exchange", ignoreDeclarationExceptions = "true")))
+public void handlePerson(Person person) {
+	this.person = person;
+}
[Note]Note

The message is directly handed over to the onMessage method of the +MessageListener associated with the matching SimpleMessageListenerContainer.

Spring AMQP Test Configuration

In order to avoid Spring AMQP trying to connect to a running broker during our tests +configure a mock ConnectionFactory.

To disable the mocked ConnectionFactory, set the following property: +stubrunner.amqp.mockConnection=false

stubrunner:
+  amqp:
+    mockConnection: false

91. Contract DSL

Spring Cloud Contract supports out of the box 2 types of DSL. One written in +Groovy and one written in YAML.

If you decide to write the contract in Groovy, do not be alarmed if you have not used Groovy +before. Knowledge of the language is not really needed, as the Contract DSL uses only a +tiny subset of it (only literals, method calls and closures). Also, the DSL is statically +typed, to make it programmer-readable without any knowledge of the DSL itself.

[Important]Important

Remember that, inside the Groovy contract file, you have to provide the fully +qualified name to the Contract class and make static imports, such as +org.springframework.cloud.spec.Contract.make { …​ }. You can also provide an import to +the Contract class: import org.springframework.cloud.spec.Contract and then call +Contract.make { …​ }.

[Tip]Tip

Spring Cloud Contract supports defining multiple contracts in a single file.

The following is a complete example of a Groovy contract definition:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'PUT'
+		url '/api/12'
+		headers {
+			header 'Content-Type': 'application/vnd.org.springframework.cloud.contract.verifier.twitter-places-analyzer.v1+json'
+		}
+		body '''\
+		[{
+			"created_at": "Sat Jul 26 09:38:57 +0000 2014",
+			"id": 492967299297845248,
+			"id_str": "492967299297845248",
+			"text": "Gonna see you at Warsaw",
+			"place":
+			{
+				"attributes":{},
+				"bounding_box":
+				{
+					"coordinates":
+						[[
+							[-77.119759,38.791645],
+							[-76.909393,38.791645],
+							[-76.909393,38.995548],
+							[-77.119759,38.995548]
+						]],
+					"type":"Polygon"
+				},
+				"country":"United States",
+				"country_code":"US",
+				"full_name":"Washington, DC",
+				"id":"01fbe706f872cb32",
+				"name":"Washington",
+				"place_type":"city",
+				"url": "https://api.twitter.com/1/geo/id/01fbe706f872cb32.json"
+			}
+		}]
+	'''
+	}
+	response {
+		status 200
+	}
+}

The following is a complete example of a YAML contract definition:

description: Some description
+name: some name
+priority: 8
+ignored: true
+request:
+  url: /foo
+  queryParameters:
+    a: b
+    b: c
+  method: PUT
+  headers:
+    foo: bar
+    fooReq: baz
+  body:
+    foo: bar
+  matchers:
+    body:
+      - path: $.foo
+        type: by_regex
+        value: bar
+    headers:
+      - key: foo
+        regex: bar
+response:
+  status: 200
+  headers:
+    foo2: bar
+    foo3: foo33
+    fooRes: baz
+  body:
+    foo2: bar
+    foo3: baz
+  matchers:
+    body:
+      - path: $.foo2
+        type: by_regex
+        value: bar
+      - path: $.foo3
+        type: by_command
+        value: executeMe($it)
+    headers:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        command: andMeToo($it)
[Tip]Tip

You can compile contracts to stubs mapping using standalone maven command: +mvn org.springframework.cloud:spring-cloud-contract-maven-plugin:convert

91.1 Limitations

[Warning]Warning

Spring Cloud Contract Verifier does not properly support XML. Please use JSON or +help us implement this feature.

[Warning]Warning

The support for verifying the size of JSON arrays is experimental. If you want +to turn it on, please set the value of the following system property to true: +spring.cloud.contract.verifier.assert.size. By default, this feature is set to false. +You can also provide the assertJsonSize property in the plugin configuration.

[Warning]Warning

Because JSON structure can have any form, it can be impossible to parse it +properly when using the Groovy DSL and the value(consumer(…​), producer(…​)) notation in GString. That +is why you should use the Groovy Map notation.

91.2 Common Top-Level elements

The following sections describe the most common top-level elements:

91.2.1 Description

You can add a description to your contract. The description is arbitrary text. The +following code shows an example:

Groovy DSL.  +

		org.springframework.cloud.contract.spec.Contract.make {
+			description('''
+given:
+	An input
+when:
+	Sth happens
+then:
+	Output
+''')
+		}

+

YAML.  +

description: Some description
+name: some name
+priority: 8
+ignored: true
+request:
+  url: /foo
+  queryParameters:
+    a: b
+    b: c
+  method: PUT
+  headers:
+    foo: bar
+    fooReq: baz
+  body:
+    foo: bar
+  matchers:
+    body:
+      - path: $.foo
+        type: by_regex
+        value: bar
+    headers:
+      - key: foo
+        regex: bar
+response:
+  status: 200
+  headers:
+    foo2: bar
+    foo3: foo33
+    fooRes: baz
+  body:
+    foo2: bar
+    foo3: baz
+  matchers:
+    body:
+      - path: $.foo2
+        type: by_regex
+        value: bar
+      - path: $.foo3
+        type: by_command
+        value: executeMe($it)
+    headers:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        command: andMeToo($it)

+

91.2.2 Name

You can provide a name for your contract. Assume that you provided the following name: +should register a user. If you do so, the name of the autogenerated test is +validate_should_register_a_user. Also, the name of the stub in a WireMock stub is +should_register_a_user.json.

[Important]Important

You must ensure that the name does not contain any characters that make the +generated test not compile. Also, remember that, if you provide the same name for +multiple contracts, your autogenerated tests fail to compile and your generated stubs +override each other.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	name("some_special_name")
+}

+

YAML.  +

name: some name

+

91.2.3 Ignoring Contracts

If you want to ignore a contract, you can either set a value of ignored contracts in the +plugin configuration or set the ignored property on the contract itself:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	ignored()
+}

+

YAML.  +

ignored: true

+

91.2.4 Passing Values from Files

Starting with version 1.2.0, you can pass values from files. Assume that you have the +following resources in our project.

└── src
+    └── test
+        └── resources
+            └── contracts
+                ├── readFromFile.groovy
+                ├── request.json
+                └── response.json

Further assume that your contract is as follows:

Groovy DSL.  +

import org.springframework.cloud.contract.spec.Contract
+
+Contract.make {
+	request {
+		method('PUT')
+		headers {
+			contentType(applicationJson())
+		}
+		body(file("request.json"))
+		url("/1")
+	}
+	response {
+		status 200
+		body(file("response.json"))
+		headers {
+			contentType(textPlain())
+		}
+	}
+}

+

YAML.  +

request:
+  method: GET
+  url: /foo
+  bodyFromFile: request.json
+response:
+  status: 200
+  bodyFromFile: response.json

+

Further assume that the JSON files is as follows:

request.json

{ "status" : "REQUEST" }

response.json

{ "status" : "RESPONSE" }

When test or stub generation takes place, the contents of the file is passed to the body +of a request or a response. The name of the file needs to be a file with location +relative to the folder in which the contract lays.

91.2.5 HTTP Top-Level Elements

The following methods can be called in the top-level closure of a contract definition. +request and response are mandatory. priority is optional.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	// Definition of HTTP request part of the contract
+	// (this can be a valid request or invalid depending
+	// on type of contract being specified).
+	request {
+		//...
+	}
+
+	// Definition of HTTP response part of the contract
+	// (a service implementing this contract should respond
+	// with following response after receiving request
+	// specified in "request" part above).
+	response {
+		//...
+	}
+
+	// Contract priority, which can be used for overriding
+	// contracts (1 is highest). Priority is optional.
+	priority 1
+}

+

YAML.  +

priority: 8
+request:
+...
+response:
+...

+

[Important]Important

If you want to make your contract have a higher value of priority +you need to pass a lower number to the priority tag / method. E.g. priority with +value 5 has higher priority than priority with value 10.

91.3 Request

The HTTP protocol requires only method and url to be specified in a request. The +same information is mandatory in request definition of the Contract.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		// HTTP request method (GET/POST/PUT/DELETE).
+		method 'GET'
+
+		// Path component of request URL is specified as follows.
+		urlPath('/users')
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

method: PUT
+url: /foo

+

It is possible to specify an absolute rather than relative url, but using urlPath is +the recommended way, as doing so makes the tests host-independent.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'GET'
+
+		// Specifying `url` and `urlPath` in one contract is illegal.
+		url('http://localhost:8888/users')
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+  method: PUT
+  urlPath: /foo

+

request may contain query parameters.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		urlPath('/users') {
+
+			// Each parameter is specified in form
+			// `'paramName' : paramValue` where parameter value
+			// may be a simple literal or one of matcher functions,
+			// all of which are used in this example.
+			queryParameters {
+
+				// If a simple literal is used as value
+				// default matcher function is used (equalTo)
+				parameter 'limit': 100
+
+				// `equalTo` function simply compares passed value
+				// using identity operator (==).
+				parameter 'filter': equalTo("email")
+
+				// `containing` function matches strings
+				// that contains passed substring.
+				parameter 'gender': value(consumer(containing("[mf]")), producer('mf'))
+
+				// `matching` function tests parameter
+				// against passed regular expression.
+				parameter 'offset': value(consumer(matching("[0-9]+")), producer(123))
+
+				// `notMatching` functions tests if parameter
+				// does not match passed regular expression.
+				parameter 'loginStartsWith': value(consumer(notMatching(".{0,2}")), producer(3))
+			}
+		}
+
+		//...
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+  queryParameters:
+    a: b
+    b: c
+  headers:
+    foo: bar
+    fooReq: baz
+  cookies:
+    foo: bar
+    fooReq: baz
+  body:
+    foo: bar
+  matchers:
+    body:
+      - path: $.foo
+        type: by_regex
+        value: bar
+    headers:
+      - key: foo
+        regex: bar
+response:
+  status: 200
+  fixedDelayMilliseconds: 1000
+  headers:
+    foo2: bar
+    foo3: foo33
+    fooRes: baz
+  body:
+    foo2: bar
+    foo3: baz
+  matchers:
+    body:
+      - path: $.foo2
+        type: by_regex
+        value: bar
+      - path: $.foo3
+        type: by_command
+        value: executeMe($it)
+    headers:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        command: andMeToo($it)
+    cookies:
+      - key: foo2
+        regex: bar
+      - key: foo3
+        predefined:

+

request may contain additional request headers, as shown in the following example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		// Each header is added in form `'Header-Name' : 'Header-Value'`.
+		// there are also some helper methods
+		headers {
+			header 'key': 'value'
+			contentType(applicationJson())
+		}
+
+		//...
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+headers:
+  foo: bar
+  fooReq: baz

+

request may contain additional request cookies, as shown in the following example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		// Each Cookies is added in form `'Cookie-Key' : 'Cookie-Value'`.
+		// there are also some helper methods
+		cookies {
+			cookie 'key': 'value'
+			cookie('another_key', 'another_value')
+		}
+
+		//...
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+cookies:
+  foo: bar
+  fooReq: baz

+

request may contain a request body:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+
+		// Currently only JSON format of request body is supported.
+		// Format will be determined from a header or body's content.
+		body '''{ "login" : "john", "name": "John The Contract" }'''
+	}
+
+	response {
+		//...
+	}
+}

+

YAML.  +

request:
+...
+body:
+  foo: bar

+

request may contain multipart elements. To include multipart elements, use the +multipart method/section, as shown in the following examples

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract contractDsl = org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method "PUT"
+		url "/multipart"
+		headers {
+			contentType('multipart/form-data;boundary=AaB03x')
+		}
+		multipart(
+				// key (parameter name), value (parameter value) pair
+				formParameter: $(c(regex('".+"')), p('"formParameterValue"')),
+				someBooleanParameter: $(c(regex(anyBoolean())), p('true')),
+				// a named parameter (e.g. with `file` name) that represents file with
+				// `name` and `content`. You can also call `named("fileName", "fileContent")`
+				file: named(
+						// name of the file
+						name: $(c(regex(nonEmpty())), p('filename.csv')),
+						// content of the file
+						content: $(c(regex(nonEmpty())), p('file content')),
+						// content type for the part
+						contentType: $(c(regex(nonEmpty())), p('application/json')))
+		)
+	}
+	response {
+		status 200
+	}
+}

+

YAML.  +

request:
+  method: PUT
+  url: /multipart
+  headers:
+    Content-Type: multipart/form-data;boundary=AaB03x
+  multipart:
+    params:
+    # key (parameter name), value (parameter value) pair
+      formParameter: '"formParameterValue"'
+      someBooleanParameter: true
+    named:
+      - paramName: file
+        fileName: filename.csv
+        fileContent: file content
+  matchers:
+    multipart:
+      params:
+        - key: formParameter
+          regex: ".+"
+        - key: someBooleanParameter
+          predefined: any_boolean
+      named:
+        - paramName: file
+          fileName:
+            predefined: non_empty
+          fileContent:
+            predefined: non_empty
+response:
+  status: 200

+

In the preceding example, we define parameters in either of two ways:

Groovy DSL

  • Directly, by using the map notation, where the value can be a dynamic property (such as +formParameter: $(consumer(…​), producer(…​))).
  • By using the named(…​) method that lets you set a named parameter. A named parameter +can set a name and content. You can call it either via a method with two arguments, +such as named("fileName", "fileContent"), or via a map notation, such as +named(name: "fileName", content: "fileContent").

YAML

  • The multipart parameters are set via multipart.params section
  • The named parameters (the fileName and fileContent for a given parameter name) +can be set via the multipart.named section. That section contains +the paramName (name of the parameter), fileName (name of the file), +fileContent (content of the file) fields

  • The dynamic bits can be set via the matchers.multipart section

    • for parameters use the params section that can accept +regex or a predefined regular expression
    • for named params use the named section where first you +define the parameter name via paramName and then you can pass the +parametrization of either fileName or fileContent via +regex or a predefined regular expression

From this contract, the generated test is as follows:

// given:
+ MockMvcRequestSpecification request = given()
+   .header("Content-Type", "multipart/form-data;boundary=AaB03x")
+   .param("formParameter", "\"formParameterValue\"")
+   .param("someBooleanParameter", "true")
+   .multiPart("file", "filename.csv", "file content".getBytes());
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .put("/multipart");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);

The WireMock stub is as follows:

			'''
+{
+  "request" : {
+	"url" : "/multipart",
+	"method" : "PUT",
+	"headers" : {
+	  "Content-Type" : {
+		"matches" : "multipart/form-data;boundary=AaB03x.*"
+	  }
+	},
+	"bodyPatterns" : [ {
+		"matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"formParameter\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n\\".+\\"\\r\\n--\\\\1.*"
+  		}, {
+    			"matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"someBooleanParameter\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n(true|false)\\r\\n--\\\\1.*"
+  		}, {
+	  "matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"file\\"; filename=\\"[\\\\S\\\\s]+\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n[\\\\S\\\\s]+\\r\\n--\\\\1.*"
+	} ]
+  },
+  "response" : {
+	"status" : 200,
+	"transformers" : [ "response-template", "foo-transformer" ]
+  }
+}
+	'''

91.4 Response

The response must contain an HTTP status code and may contain other information. The +following code shows an example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		//...
+	}
+	response {
+		// Status code sent by the server
+		// in response to request specified above.
+		status 200
+	}
+}

+

YAML.  +

response:
+...
+status: 200

+

Besides status, the response may contain headers, cookies and a body, both of which are +specified the same way as in the request (see the previous paragraph).

91.5 Dynamic properties

The contract can contain some dynamic properties: timestamps, IDs, and so on. You do not +want to force the consumers to stub their clocks to always return the same value of time +so that it gets matched by the stub.

For Groovy DSL you can provide the dynamic parts in your contracts +in two ways: pass them directly in the body or set them in separate sections called +testMatchers and stubMatchers.

For YAML you can only use the matchers section.

91.5.1 Dynamic properties inside the body

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

You can set the properties inside the body either with the value method or, if you use +the Groovy map notation, with $(). The following example shows how to set dynamic +properties with the value method:

value(consumer(...), producer(...))
+value(c(...), p(...))
+value(stub(...), test(...))
+value(client(...), server(...))

The following example shows how to set dynamic properties with $():

$(consumer(...), producer(...))
+$(c(...), p(...))
+$(stub(...), test(...))
+$(client(...), server(...))

Both approaches work equally well. stub and client methods are aliases over the consumer +method. Subsequent sections take a closer look at what you can do with those values.

91.5.2 Regular expressions

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

You can use regular expressions to write your requests in Contract DSL. Doing so is +particularly useful when you want to indicate that a given response should be provided +for requests that follow a given pattern. Also, you can use regular expressions when you +need to use patterns and not exact values both for your test and your server side tests.

The following example shows how to use regular expressions to write a request:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method('GET')
+		url $(consumer(~/\/[0-9]{2}/), producer('/12'))
+	}
+	response {
+		status 200
+		body(
+				id: $(anyNumber()),
+				surname: $(
+						consumer('Kowalsky'),
+						producer(regex('[a-zA-Z]+'))
+				),
+				name: 'Jan',
+				created: $(consumer('2014-02-02 12:23:43'), producer(execute('currentDate(it)'))),
+				correlationId: value(consumer('5d1f9fef-e0dc-4f3d-a7e4-72d2220dd827'),
+						producer(regex('[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}'))
+				)
+		)
+		headers {
+			header 'Content-Type': 'text/plain'
+		}
+	}
+}

You can also provide only one side of the communication with a regular expression. If you +do so, then the contract engine automatically provides the generated string that matches +the provided regular expression. The following code shows an example:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'PUT'
+		url value(consumer(regex('/foo/[0-9]{5}')))
+		body([
+			requestElement: $(consumer(regex('[0-9]{5}')))
+		])
+		headers {
+			header('header', $(consumer(regex('application\\/vnd\\.fraud\\.v1\\+json;.*'))))
+		}
+	}
+	response {
+		status 200
+		body([
+			responseElement: $(producer(regex('[0-9]{7}')))
+		])
+		headers {
+			contentType("application/vnd.fraud.v1+json")
+		}
+	}
+}

In the preceding example, the opposite side of the communication has the respective data +generated for request and response.

Spring Cloud Contract comes with a series of predefined regular expressions that you can +use in your contracts, as shown in the following example:

protected static final Pattern TRUE_OR_FALSE = Pattern.compile(/(true|false)/)
+protected static final Pattern ONLY_ALPHA_UNICODE = Pattern.compile(/[\p{L}]*/)
+protected static final Pattern NUMBER = Pattern.compile('-?(\\d*\\.\\d+|\\d+)')
+protected static final Pattern IP_ADDRESS = Pattern.compile('([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])')
+protected static final Pattern HOSTNAME_PATTERN = Pattern.compile('((http[s]?|ftp):/)/?([^:/\\s]+)(:[0-9]{1,5})?')
+protected static final Pattern EMAIL = Pattern.compile('[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6}')
+protected static final Pattern URL = UrlHelper.URL
+protected static final Pattern UUID = Pattern.compile('[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}')
+protected static final Pattern ANY_DATE = Pattern.compile('(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])')
+protected static final Pattern ANY_DATE_TIME = Pattern.compile('([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])')
+protected static final Pattern ANY_TIME = Pattern.compile('(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])')
+protected static final Pattern NON_EMPTY = Pattern.compile(/[\S\s]+/)
+protected static final Pattern NON_BLANK = Pattern.compile(/^\s*\S[\S\s]*/)
+protected static final Pattern ISO8601_WITH_OFFSET = Pattern.compile(/([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.\d{3})?(Z|[+-][01]\d:[0-5]\d)/)
+
+protected static Pattern anyOf(String... values){
+	return Pattern.compile(values.collect({"^$it\$"}).join("|"))
+}
+
+String onlyAlphaUnicode() {
+	return ONLY_ALPHA_UNICODE.pattern()
+}
+
+String number() {
+	return NUMBER.pattern()
+}
+
+String anyBoolean() {
+	return TRUE_OR_FALSE.pattern()
+}
+
+String ipAddress() {
+	return IP_ADDRESS.pattern()
+}
+
+String hostname() {
+	return HOSTNAME_PATTERN.pattern()
+}
+
+String email() {
+	return EMAIL.pattern()
+}
+
+String url() {
+	return URL.pattern()
+}
+
+String uuid(){
+	return UUID.pattern()
+}
+
+String isoDate() {
+	return ANY_DATE.pattern()
+}
+
+String isoDateTime() {
+	return ANY_DATE_TIME.pattern()
+}
+
+String isoTime() {
+	return ANY_TIME.pattern()
+}
+
+String iso8601WithOffset() {
+	return ISO8601_WITH_OFFSET.pattern()
+}
+
+String nonEmpty() {
+	return NON_EMPTY.pattern()
+}
+
+String nonBlank() {
+	return NON_BLANK.pattern()
+}

In your contract, you can use it as shown in the following example:

Contract dslWithOptionalsInString = Contract.make {
+	priority 1
+	request {
+		method POST()
+		url '/users/password'
+		headers {
+			contentType(applicationJson())
+		}
+		body(
+				email: $(consumer(optional(regex(email()))), producer('abc@abc.com')),
+				callback_url: $(consumer(regex(hostname())), producer('https://partners.com'))
+		)
+	}
+	response {
+		status 404
+		headers {
+			contentType(applicationJson())
+		}
+		body(
+				code: value(consumer("123123"), producer(optional("123123"))),
+				message: "User not found by email = [${value(producer(regex(email())), consumer('not.existing@user.com'))}]"
+		)
+	}
+}

91.5.3 Passing Optional Parameters

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

It is possible to provide optional parameters in your contract. However, you can provide +optional parameters only for the following:

  • STUB side of the Request
  • TEST side of the Response

The following example shows how to provide optional parameters:

org.springframework.cloud.contract.spec.Contract.make {
+	priority 1
+	request {
+		method 'POST'
+		url '/users/password'
+		headers {
+			contentType(applicationJson())
+		}
+		body(
+				email: $(consumer(optional(regex(email()))), producer('abc@abc.com')),
+				callback_url: $(consumer(regex(hostname())), producer('https://partners.com'))
+		)
+	}
+	response {
+		status 404
+		headers {
+			header 'Content-Type': 'application/json'
+		}
+		body(
+				code: value(consumer("123123"), producer(optional("123123")))
+		)
+	}
+}

By wrapping a part of the body with the optional() method, you create a regular +expression that must be present 0 or more times.

If you use Spock for, the following test would be generated from the previous example:

"""
+ given:
+  def request = given()
+    .header("Content-Type", "application/json")
+    .body('''{"email":"abc@abc.com","callback_url":"https://partners.com"}''')
+
+ when:
+  def response = given().spec(request)
+    .post("/users/password")
+
+ then:
+  response.statusCode == 404
+  response.header('Content-Type')  == 'application/json'
+ and:
+  DocumentContext parsedJson = JsonPath.parse(response.body.asString())
+  assertThatJson(parsedJson).field("['code']").matches("(123123)?")
+"""

The following stub would also be generated:

'''
+{
+  "request" : {
+	"url" : "/users/password",
+	"method" : "POST",
+	"bodyPatterns" : [ {
+	  "matchesJsonPath" : "$[?(@.['email'] =~ /([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\\\.[a-zA-Z]{2,6})?/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.['callback_url'] =~ /((http[s]?|ftp):\\\\/)\\\\/?([^:\\\\/\\\\s]+)(:[0-9]{1,5})?/)]"
+	} ],
+	"headers" : {
+	  "Content-Type" : {
+		"equalTo" : "application/json"
+	  }
+	}
+  },
+  "response" : {
+	"status" : 404,
+	"body" : "{\\"code\\":\\"123123\\",\\"message\\":\\"User not found by email == [not.existing@user.com]\\"}",
+	"headers" : {
+	  "Content-Type" : "application/json"
+	}
+  },
+  "priority" : 1
+}
+'''

91.5.4 Executing Custom Methods on the Server Side

[Important]Important

This section is valid only for Groovy DSL. Check out the +Section 91.5.7, “Dynamic Properties in the Matchers Sections” section for YAML examples of a similar feature.

You can define a method call that executes on the server side during the test. Such a +method can be added to the class defined as "baseClassForTests" in the configuration. The +following code shows an example of the contract portion of the test case:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'PUT'
+		url $(consumer(regex('^/api/[0-9]{2}$')), producer('/api/12'))
+		headers {
+			header 'Content-Type': 'application/json'
+		}
+		body '''\
+				[{
+					"text": "Gonna see you at Warsaw"
+				}]
+			'''
+	}
+	response {
+		body (
+				path: $(consumer('/api/12'), producer(regex('^/api/[0-9]{2}$'))),
+				correlationId: $(consumer('1223456'), producer(execute('isProperCorrelationId($it)')))
+		)
+		status 200
+	}
+}

The following code shows the base class portion of the test case:

abstract class BaseMockMvcSpec extends Specification {
+
+	def setup() {
+		RestAssuredMockMvc.standaloneSetup(new PairIdController())
+	}
+
+	void isProperCorrelationId(Integer correlationId) {
+		assert correlationId == 123456
+	}
+
+	void isEmpty(String value) {
+		assert value == null
+	}
+
+}
[Important]Important

You cannot use both a String and execute to perform concatenation. For +example, calling header('Authorization', 'Bearer ' + execute('authToken()')) leads to +improper results. Instead, call header('Authorization', execute('authToken()')) and +ensure that the authToken() method returns everything you need.

The type of the object read from the JSON can be one of the following, depending on the +JSON path:

  • String: If you point to a String value in the JSON.
  • JSONArray: If you point to a List in the JSON.
  • Map: If you point to a Map in the JSON.
  • Number: If you point to Integer, Double etc. in the JSON.
  • Boolean: If you point to a Boolean in the JSON.

In the request part of the contract, you can specify that the body should be taken from +a method.

[Important]Important

You must provide both the consumer and the producer side. The execute part +is applied for the whole body - not for parts of it.

The following example shows how to read an object from JSON:

Contract contractDsl = Contract.make {
+	request {
+		method 'GET'
+		url '/something'
+		body(
+				$(c("foo"), p(execute("hashCode()")))
+		)
+	}
+	response {
+		status 200
+	}
+}

The preceding example results in calling the hashCode() method in the request body. +It should resemble the following code:

// given:
+ MockMvcRequestSpecification request = given()
+   .body(hashCode());
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .get("/something");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);

91.5.5 Referencing the Request from the Response

The best situation is to provide fixed values, but sometimes you need to reference a +request in your response.

If you’re writing contracts using Groovy DSL, you can use the fromRequest() method, which lets +you reference a bunch of elements from the HTTP request. You can use the following +options:

  • fromRequest().url(): Returns the request URL and query parameters.
  • fromRequest().query(String key): Returns the first query parameter with a given name.
  • fromRequest().query(String key, int index): Returns the nth query parameter with a +given name.
  • fromRequest().path(): Returns the full path.
  • fromRequest().path(int index): Returns the nth path element.
  • fromRequest().header(String key): Returns the first header with a given name.
  • fromRequest().header(String key, int index): Returns the nth header with a given name.
  • fromRequest().body(): Returns the full request body.
  • fromRequest().body(String jsonPath): Returns the element from the request that +matches the JSON Path.

If you’re using the YAML contract definition you have to use the +Handlebars {{{ }}} notation with custom, Spring Cloud Contract + functions to achieve this.

  • {{{ request.url }}}: Returns the request URL and query parameters.
  • {{{ request.query.key.[index] }}}: Returns the nth query parameter with a given name. +E.g. for key foo, first entry {{{ request.query.foo.[0] }}}
  • {{{ request.path }}}: Returns the full path.
  • {{{ request.path.[index] }}}: Returns the nth path element. E.g. +for first entry `{{{ request.path.[0] }}}
  • {{{ request.headers.key }}}: Returns the first header with a given name.
  • {{{ request.headers.key.[index] }}}: Returns the nth header with a given name.
  • {{{ request.body }}}: Returns the full request body.
  • {{{ jsonpath this 'your.json.path' }}}: Returns the element from the request that +matches the JSON Path. E.g. for json path $.foo - {{{ jsonpath this '$.foo' }}}

Consider the following contract:

Groovy DSL.  +

Contract contractDsl = Contract.make {
+	request {
+		method 'GET'
+		url('/api/v1/xxxx') {
+			queryParameters {
+				parameter("foo", "bar")
+				parameter("foo", "bar2")
+			}
+		}
+		headers {
+			header(authorization(), "secret")
+			header(authorization(), "secret2")
+		}
+		body(foo: "bar", baz: 5)
+	}
+	response {
+		status 200
+		headers {
+			header(authorization(), "foo ${fromRequest().header(authorization())} bar")
+		}
+		body(
+				url: fromRequest().url(),
+				path: fromRequest().path(),
+				pathIndex: fromRequest().path(1),
+				param: fromRequest().query("foo"),
+				paramIndex: fromRequest().query("foo", 1),
+				authorization: fromRequest().header("Authorization"),
+				authorization2: fromRequest().header("Authorization", 1),
+				fullBody: fromRequest().body(),
+				responseFoo: fromRequest().body('$.foo'),
+				responseBaz: fromRequest().body('$.baz'),
+				responseBaz2: "Bla bla ${fromRequest().body('$.foo')} bla bla"
+		)
+	}
+}

+

YAML.  +

request:
+  method: GET
+  url: /api/v1/xxxx
+  queryParameters:
+    foo:
+      - bar
+      - bar2
+  headers:
+    Authorization:
+      - secret
+      - secret2
+  body:
+    foo: bar
+    baz: 5
+response:
+  status: 200
+  headers:
+    Authorization: "foo {{{ request.headers.Authorization.0 }}} bar"
+  body:
+    url: "{{{ request.url }}}"
+    path: "{{{ request.path }}}"
+    pathIndex: "{{{ request.path.1 }}}"
+    param: "{{{ request.query.foo }}}"
+    paramIndex: "{{{ request.query.foo.1 }}}"
+    authorization: "{{{ request.headers.Authorization.0 }}}"
+    authorization2: "{{{ request.headers.Authorization.1 }}"
+    fullBody: "{{{ request.body }}}"
+    responseFoo: "{{{ jsonpath this '$.foo' }}}"
+    responseBaz: "{{{ jsonpath this '$.baz' }}}"
+    responseBaz2: "Bla bla {{{ jsonpath this '$.foo' }}} bla bla"

+

Running a JUnit test generation leads to a test that resembles the following example:

// given:
+ MockMvcRequestSpecification request = given()
+   .header("Authorization", "secret")
+   .header("Authorization", "secret2")
+   .body("{\"foo\":\"bar\",\"baz\":5}");
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .queryParam("foo","bar")
+   .queryParam("foo","bar2")
+   .get("/api/v1/xxxx");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);
+ assertThat(response.header("Authorization")).isEqualTo("foo secret bar");
+// and:
+ DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+ assertThatJson(parsedJson).field("['fullBody']").isEqualTo("{\"foo\":\"bar\",\"baz\":5}");
+ assertThatJson(parsedJson).field("['authorization']").isEqualTo("secret");
+ assertThatJson(parsedJson).field("['authorization2']").isEqualTo("secret2");
+ assertThatJson(parsedJson).field("['path']").isEqualTo("/api/v1/xxxx");
+ assertThatJson(parsedJson).field("['param']").isEqualTo("bar");
+ assertThatJson(parsedJson).field("['paramIndex']").isEqualTo("bar2");
+ assertThatJson(parsedJson).field("['pathIndex']").isEqualTo("v1");
+ assertThatJson(parsedJson).field("['responseBaz']").isEqualTo(5);
+ assertThatJson(parsedJson).field("['responseFoo']").isEqualTo("bar");
+ assertThatJson(parsedJson).field("['url']").isEqualTo("/api/v1/xxxx?foo=bar&foo=bar2");
+ assertThatJson(parsedJson).field("['responseBaz2']").isEqualTo("Bla bla bar bla bla");

As you can see, elements from the request have been properly referenced in the response.

The generated WireMock stub should resemble the following example:

{
+  "request" : {
+    "urlPath" : "/api/v1/xxxx",
+    "method" : "POST",
+    "headers" : {
+      "Authorization" : {
+        "equalTo" : "secret2"
+      }
+    },
+    "queryParameters" : {
+      "foo" : {
+        "equalTo" : "bar2"
+      }
+    },
+    "bodyPatterns" : [ {
+      "matchesJsonPath" : "$[?(@.['baz'] == 5)]"
+    }, {
+      "matchesJsonPath" : "$[?(@.['foo'] == 'bar')]"
+    } ]
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "{\"authorization\":\"{{{request.headers.Authorization.[0]}}}\",\"path\":\"{{{request.path}}}\",\"responseBaz\":{{{jsonpath this '$.baz'}}} ,\"param\":\"{{{request.query.foo.[0]}}}\",\"pathIndex\":\"{{{request.path.[1]}}}\",\"responseBaz2\":\"Bla bla {{{jsonpath this '$.foo'}}} bla bla\",\"responseFoo\":\"{{{jsonpath this '$.foo'}}}\",\"authorization2\":\"{{{request.headers.Authorization.[1]}}}\",\"fullBody\":\"{{{escapejsonbody}}}\",\"url\":\"{{{request.url}}}\",\"paramIndex\":\"{{{request.query.foo.[1]}}}\"}",
+    "headers" : {
+      "Authorization" : "{{{request.headers.Authorization.[0]}}};foo"
+    },
+    "transformers" : [ "response-template" ]
+  }
+}

Sending a request such as the one presented in the request part of the contract results +in sending the following response body:

{
+  "url" : "/api/v1/xxxx?foo=bar&foo=bar2",
+  "path" : "/api/v1/xxxx",
+  "pathIndex" : "v1",
+  "param" : "bar",
+  "paramIndex" : "bar2",
+  "authorization" : "secret",
+  "authorization2" : "secret2",
+  "fullBody" : "{\"foo\":\"bar\",\"baz\":5}",
+  "responseFoo" : "bar",
+  "responseBaz" : 5,
+  "responseBaz2" : "Bla bla bar bla bla"
+}
[Important]Important

This feature works only with WireMock having a version greater than or equal +to 2.5.1. The Spring Cloud Contract Verifier uses WireMock’s +response-template response transformer. It uses Handlebars to convert the Mustache {{{ }}} templates into +proper values. Additionally, it registers two helper functions:

  • escapejsonbody: Escapes the request body in a format that can be embedded in a JSON.
  • jsonpath: For a given parameter, find an object in the request body.

91.5.6 Registering Your Own WireMock Extension

WireMock lets you register custom extensions. By default, Spring Cloud Contract registers +the transformer, which lets you reference a request from a response. If you want to +provide your own extensions, you can register an implementation of the +org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions interface. +Since we use the spring.factories extension approach, you can create an entry in +META-INF/spring.factories file similar to the following:

org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions=\
+org.springframework.cloud.contract.stubrunner.provider.wiremock.TestWireMockExtensions

The following is an example of a custom extension:

TestWireMockExtensions.groovy.  +

package org.springframework.cloud.contract.verifier.dsl.wiremock
+
+import com.github.tomakehurst.wiremock.extension.Extension
+
+/**
+ * Extension that registers the default transformer and the custom one
+ */
+class TestWireMockExtensions implements WireMockExtensions {
+	@Override
+	List<Extension> extensions() {
+		return [
+				new DefaultResponseTransformer(),
+				new CustomExtension()
+		]
+	}
+}
+
+class CustomExtension implements Extension {
+
+	@Override
+	String getName() {
+		return "foo-transformer"
+	}
+}

+

[Important]Important

Remember to override the applyGlobally() method and set it to false if you +want the transformation to be applied only for a mapping that explicitly requires it.

91.5.7 Dynamic Properties in the Matchers Sections

If you work with Pact, the following discussion may seem familiar. +Quite a few users are used to having a separation between the body and setting the +dynamic parts of a contract.

You can use two separate sections:

  • stubMatchers, which lets you define the dynamic values that should end up in a stub. +You can set it in the request or inputMessage part of your contract.
  • testMatchers, which is present in the response or outputMessage side of the +contract.

Currently, Spring Cloud Contract Verifier supports only JSON Path-based matchers with the +following matching possibilities:

Groovy DSL

  • For stubMatchers:

    • byEquality(): The value taken from the request via the provided JSON Path must be +equal to the value provided in the contract.
    • byRegex(…​): The value taken from the request via the provided JSON Path must +match the regex.
    • byDate(): The value taken from the request via the provided JSON Path must +match the regex for an ISO Date value.
    • byTimestamp(): The value taken from the request via the provided JSON Path must +match the regex for an ISO DateTime value.
    • byTime(): The value taken from the request via the provided JSON Path must +match the regex for an ISO Time value.

  • For testMatchers:

    • byEquality(): The value taken from the response via the provided JSON Path must be +equal to the provided value in the contract.
    • byRegex(…​): The value taken from the response via the provided JSON Path must +match the regex.
    • byDate(): The value taken from the response via the provided JSON Path must match +the regex for an ISO Date value.
    • byTimestamp(): The value taken from the response via the provided JSON Path must +match the regex for an ISO DateTime value.
    • byTime(): The value taken from the response via the provided JSON Path must match +the regex for an ISO Time value.
    • byType(): The value taken from the response via the provided JSON Path needs to be +of the same type as the type defined in the body of the response in the contract. +byType can take a closure, in which you can set minOccurrence and maxOccurrence. +That way, you can assert the size of the flattened collection. To check the size of an +unflattened collection, use a custom method with the byCommand(…​) testMatcher.

    • byCommand(…​): The value taken from the response via the provided JSON Path is +passed as an input to the custom method that you provide. For example, +byCommand('foo($it)') results in calling a foo method to which the value matching the +JSON Path gets passed. The type of the object read from the JSON can be one of the +following, depending on the JSON path:

      • String: If you point to a String value.
      • JSONArray: If you point to a List.
      • Map: If you point to a Map.
      • Number: If you point to Integer, Double, or other kind of number.
      • Boolean: If you point to a Boolean.

YAML. Please read the Groovy section for detailed explanation of +what the types mean

For YAML the structure of a matcher looks like this

- path: $.foo
+  type: by_regex
+  value: bar

Or if you want to use one of the predefined regular expressions +[only_alpha_unicode, number, any_boolean, ip_address, hostname, +email, url, uuid, iso_date, iso_date_time, iso_time, iso_8601_with_offset, non_empty, non_blank]:

- path: $.foo
+  type: by_regex
+  predefined: only_alpha_unicode

Below you can find the allowed list of `type`s.

  • For stubMatchers:

    • by_equality
    • by_regex
    • by_date
    • by_timestamp
    • by_time

  • For testMatchers:

    • by_equality
    • by_regex
    • by_date
    • by_timestamp
    • by_time

    • by_type

      • there are 2 additional fields accepted: minOccurrence and maxOccurrence.
    • by_command

Consider the following example:

Groovy DSL.  +

Contract contractDsl = Contract.make {
+	request {
+		method 'GET'
+		urlPath '/get'
+		body([
+				duck: 123,
+				alpha: "abc",
+				number: 123,
+				aBoolean: true,
+				date: "2017-01-01",
+				dateTime: "2017-01-01T01:23:45",
+				time: "01:02:34",
+				valueWithoutAMatcher: "foo",
+				valueWithTypeMatch: "string",
+				key: [
+						'complex.key' : 'foo'
+				]
+		])
+		stubMatchers {
+			jsonPath('$.duck', byRegex("[0-9]{3}"))
+			jsonPath('$.duck', byEquality())
+			jsonPath('$.alpha', byRegex(onlyAlphaUnicode()))
+			jsonPath('$.alpha', byEquality())
+			jsonPath('$.number', byRegex(number()))
+			jsonPath('$.aBoolean', byRegex(anyBoolean()))
+			jsonPath('$.date', byDate())
+			jsonPath('$.dateTime', byTimestamp())
+			jsonPath('$.time', byTime())
+			jsonPath("\$.['key'].['complex.key']", byEquality())
+		}
+		headers {
+			contentType(applicationJson())
+		}
+	}
+	response {
+		status 200
+		body([
+				duck: 123,
+				alpha: "abc",
+				number: 123,
+				aBoolean: true,
+				date: "2017-01-01",
+				dateTime: "2017-01-01T01:23:45",
+				time: "01:02:34",
+				valueWithoutAMatcher: "foo",
+				valueWithTypeMatch: "string",
+				valueWithMin: [
+					1,2,3
+				],
+				valueWithMax: [
+					1,2,3
+				],
+				valueWithMinMax: [
+					1,2,3
+				],
+				valueWithMinEmpty: [],
+				valueWithMaxEmpty: [],
+				key: [
+				        'complex.key' : 'foo'
+				]
+		])
+		testMatchers {
+			// asserts the jsonpath value against manual regex
+			jsonPath('$.duck', byRegex("[0-9]{3}"))
+			// asserts the jsonpath value against the provided value
+			jsonPath('$.duck', byEquality())
+			// asserts the jsonpath value against some default regex
+			jsonPath('$.alpha', byRegex(onlyAlphaUnicode()))
+			jsonPath('$.alpha', byEquality())
+			jsonPath('$.number', byRegex(number()))
+			jsonPath('$.aBoolean', byRegex(anyBoolean()))
+			// asserts vs inbuilt time related regex
+			jsonPath('$.date', byDate())
+			jsonPath('$.dateTime', byTimestamp())
+			jsonPath('$.time', byTime())
+			// asserts that the resulting type is the same as in response body
+			jsonPath('$.valueWithTypeMatch', byType())
+			jsonPath('$.valueWithMin', byType {
+				// results in verification of size of array (min 1)
+				minOccurrence(1)
+			})
+			jsonPath('$.valueWithMax', byType {
+				// results in verification of size of array (max 3)
+				maxOccurrence(3)
+			})
+			jsonPath('$.valueWithMinMax', byType {
+				// results in verification of size of array (min 1 & max 3)
+				minOccurrence(1)
+				maxOccurrence(3)
+			})
+			jsonPath('$.valueWithMinEmpty', byType {
+				// results in verification of size of array (min 0)
+				minOccurrence(0)
+			})
+			jsonPath('$.valueWithMaxEmpty', byType {
+				// results in verification of size of array (max 0)
+				maxOccurrence(0)
+			})
+			// will execute a method `assertThatValueIsANumber`
+			jsonPath('$.duck', byCommand('assertThatValueIsANumber($it)'))
+			jsonPath("\$.['key'].['complex.key']", byEquality())
+		}
+		headers {
+			contentType(applicationJson())
+		}
+	}
+}

+

YAML.  +

request:
+  method: GET
+  urlPath: /get
+  body:
+    duck: 123
+    alpha: "abc"
+    number: 123
+    aBoolean: true
+    date: "2017-01-01"
+    dateTime: "2017-01-01T01:23:45"
+    time: "01:02:34"
+    valueWithoutAMatcher: "foo"
+    valueWithTypeMatch: "string"
+    key:
+      "complex.key": 'foo'
+  matchers:
+    headers:
+      - key: Content-Type
+        regex: "application/json.*"
+    body:
+      - path: $.duck
+        type: by_regex
+        value: "[0-9]{3}"
+      - path: $.duck
+        type: by_equality
+      - path: $.alpha
+        type: by_regex
+        predefined: only_alpha_unicode
+      - path: $.alpha
+        type: by_equality
+      - path: $.number
+        type: by_regex
+        predefined: number
+      - path: $.aBoolean
+        type: by_regex
+        predefined: any_boolean
+      - path: $.date
+        type: by_date
+      - path: $.dateTime
+        type: by_timestamp
+      - path: $.time
+        type: by_time
+      - path: "$.['key'].['complex.key']"
+        type: by_equality
+  headers:
+    Content-Type: application/json
+response:
+  status: 200
+  body:
+    duck: 123
+    alpha: "abc"
+    number: 123
+    aBoolean: true
+    date: "2017-01-01"
+    dateTime: "2017-01-01T01:23:45"
+    time: "01:02:34"
+    valueWithoutAMatcher: "foo"
+    valueWithTypeMatch: "string"
+    valueWithMin:
+      - 1
+      - 2
+      - 3
+    valueWithMax:
+      - 1
+      - 2
+      - 3
+    valueWithMinMax:
+      - 1
+      - 2
+      - 3
+    valueWithMinEmpty: []
+    valueWithMaxEmpty: []
+    key:
+      'complex.key' : 'foo'
+  matchers:
+    headers:
+      - key: Content-Type
+        regex: "application/json.*"
+    body:
+      - path: $.duck
+        type: by_regex
+        value: "[0-9]{3}"
+      - path: $.duck
+        type: by_equality
+      - path: $.alpha
+        type: by_regex
+        predefined: only_alpha_unicode
+      - path: $.alpha
+        type: by_equality
+      - path: $.number
+        type: by_regex
+        predefined: number
+      - path: $.aBoolean
+        type: by_regex
+        predefined: any_boolean
+      - path: $.date
+        type: by_date
+      - path: $.dateTime
+        type: by_timestamp
+      - path: $.time
+        type: by_time
+      - path: $.valueWithTypeMatch
+        type: by_type
+      - path: $.valueWithMin
+        type: by_type
+        minOccurrence: 1
+      - path: $.valueWithMax
+        type: by_type
+        maxOccurrence: 3
+      - path: $.valueWithMinMax
+        type: by_type
+        minOccurrence: 1
+        maxOccurrence: 3
+      - path: $.valueWithMinEmpty
+        type: by_type
+        minOccurrence: 0
+      - path: $.valueWithMaxEmpty
+        type: by_type
+        maxOccurrence: 0
+      - path: $.duck
+        type: by_command
+        value: assertThatValueIsANumber($it)
+  headers:
+    Content-Type: application/json

+

In the preceding example, you can see the dynamic portions of the contract in the +matchers sections. For the request part, you can see that, for all fields but +valueWithoutAMatcher, the values of the regular expressions that the stub should +contain are explicitly set. For the valueWithoutAMatcher, the verification takes place +in the same way as without the use of matchers. In that case, the test performs an +equality check.

For the response side in the testMatchers section, we define the dynamic parts in a +similar manner. The only difference is that the byType matchers are also present. The +verifier engine checks four fields to verify whether the response from the test +has a value for which the JSON path matches the given field, is of the same type as the one +defined in the response body, and passes the following check (based on the method being called):

  • For $.valueWithTypeMatch, the engine checks whether the type is the same.
  • For $.valueWithMin, the engine check the type and asserts whether the size is greater +than or equal to the minimum occurrence.
  • For $.valueWithMax, the engine checks the type and asserts whether the size is +smaller than or equal to the maximum occurrence.
  • For $.valueWithMinMax, the engine checks the type and asserts whether the size is +between the min and maximum occurrence.

The resulting test would resemble the following example (note that an and section +separates the autogenerated assertions and the assertion from matchers):

// given:
+ MockMvcRequestSpecification request = given()
+   .header("Content-Type", "application/json")
+   .body("{\"duck\":123,\"alpha\":\"abc\",\"number\":123,\"aBoolean\":true,\"date\":\"2017-01-01\",\"dateTime\":\"2017-01-01T01:23:45\",\"time\":\"01:02:34\",\"valueWithoutAMatcher\":\"foo\",\"valueWithTypeMatch\":\"string\"}");
+
+// when:
+ ResponseOptions response = given().spec(request)
+   .get("/get");
+
+// then:
+ assertThat(response.statusCode()).isEqualTo(200);
+ assertThat(response.header("Content-Type")).matches("application/json.*");
+// and:
+ DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+ assertThatJson(parsedJson).field("valueWithoutAMatcher").isEqualTo("foo");
+// and:
+ assertThat(parsedJson.read("$.duck", String.class)).matches("[0-9]{3}");
+ assertThat(parsedJson.read("$.duck", Integer.class)).isEqualTo(123);
+ assertThat(parsedJson.read("$.alpha", String.class)).matches("[\\p{L}]*");
+ assertThat(parsedJson.read("$.alpha", String.class)).isEqualTo("abc");
+ assertThat(parsedJson.read("$.number", String.class)).matches("-?\\d*(\\.\\d+)?");
+ assertThat(parsedJson.read("$.aBoolean", String.class)).matches("(true|false)");
+ assertThat(parsedJson.read("$.date", String.class)).matches("(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])");
+ assertThat(parsedJson.read("$.dateTime", String.class)).matches("([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])");
+ assertThat(parsedJson.read("$.time", String.class)).matches("(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])");
+ assertThat((Object) parsedJson.read("$.valueWithTypeMatch")).isInstanceOf(java.lang.String.class);
+ assertThat((Object) parsedJson.read("$.valueWithMin")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMin", java.util.Collection.class)).hasSizeGreaterThanOrEqualTo(1);
+ assertThat((Object) parsedJson.read("$.valueWithMax")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMax", java.util.Collection.class)).hasSizeLessThanOrEqualTo(3);
+ assertThat((Object) parsedJson.read("$.valueWithMinMax")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMinMax", java.util.Collection.class)).hasSizeBetween(1, 3);
+ assertThat((Object) parsedJson.read("$.valueWithMinEmpty")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMinEmpty", java.util.Collection.class)).hasSizeGreaterThanOrEqualTo(0);
+ assertThat((Object) parsedJson.read("$.valueWithMaxEmpty")).isInstanceOf(java.util.List.class);
+ assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMaxEmpty", java.util.Collection.class)).hasSizeLessThanOrEqualTo(0);
+ assertThatValueIsANumber(parsedJson.read("$.duck"));
[Important]Important

Notice that, for the byCommand method, the example calls the +assertThatValueIsANumber. This method must be defined in the test base class or be +statically imported to your tests. Notice that the byCommand call was converted to +assertThatValueIsANumber(parsedJson.read("$.duck"));. That means that the engine took +the method name and passed the proper JSON path as a parameter to it.

The resulting WireMock stub is in the following example:

				'''
+{
+  "request" : {
+	"urlPath" : "/get",
+	"method" : "POST",
+	"headers" : {
+	  "Content-Type" : {
+		"matches" : "application/json.*"
+	  }
+	},
+	"bodyPatterns" : [ {
+	  "matchesJsonPath" : "$[?(@.['valueWithoutAMatcher'] == 'foo')]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.['valueWithTypeMatch'] == 'string')]"
+	}, {
+	  "matchesJsonPath" : "$.['list'].['some'].['nested'][?(@.['anothervalue'] == 4)]"
+	}, {
+	  "matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['anothervalue'] == 4)]"
+	}, {
+	  "matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['json'] == 'with value')]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.duck =~ /([0-9]{3})/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.duck == 123)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.alpha =~ /([\\\\p{L}]*)/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.alpha == 'abc')]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.number =~ /(-?(\\\\d*\\\\.\\\\d+|\\\\d+))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.aBoolean =~ /((true|false))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.date =~ /((\\\\d\\\\d\\\\d\\\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01]))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.dateTime =~ /(([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]"
+	}, {
+	  "matchesJsonPath" : "$[?(@.time =~ /((2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]"
+	}, {
+	  "matchesJsonPath" : "$.list.some.nested[?(@.json =~ /(.*)/)]"
+	} ]
+  },
+  "response" : {
+	"status" : 200,
+	"body" : "{\\"date\\":\\"2017-01-01\\",\\"dateTime\\":\\"2017-01-01T01:23:45\\",\\"number\\":123,\\"aBoolean\\":true,\\"duck\\":123,\\"alpha\\":\\"abc\\",\\"valueWithMin\\":[1,2,3],\\"time\\":\\"01:02:34\\",\\"valueWithTypeMatch\\":\\"string\\",\\"valueWithMax\\":[1,2,3],\\"valueWithMinMax\\":[1,2,3],\\"valueWithoutAMatcher\\":\\"foo\\"}",
+	"headers" : {
+	  "Content-Type" : "application/json"
+	}
+  }
+}
+'''
[Important]Important

If you use a matcher, then the part of the request aned response that the +matcher addresses with the JSON Path gets removed from the assertion. In the case of +verifying a collection, you must create matchers for all the elements of the +collection.

Consider the following example:

Contract.make {
+    request {
+        method 'GET'
+        url("/foo")
+    }
+    response {
+        status 200
+        body(events: [[
+                                 operation          : 'EXPORT',
+                                 eventId            : '16f1ed75-0bcc-4f0d-a04d-3121798faf99',
+                                 status             : 'OK'
+                         ], [
+                                 operation          : 'INPUT_PROCESSING',
+                                 eventId            : '3bb4ac82-6652-462f-b6d1-75e424a0024a',
+                                 status             : 'OK'
+                         ]
+                ]
+        )
+        testMatchers {
+            jsonPath('$.events[0].operation', byRegex('.+'))
+            jsonPath('$.events[0].eventId', byRegex('^([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})$'))
+            jsonPath('$.events[0].status', byRegex('.+'))
+        }
+    }
+}

The preceding code leads to creating the following test (the code block shows only the assertion section):

and:
+	DocumentContext parsedJson = JsonPath.parse(response.body.asString())
+	assertThatJson(parsedJson).array("['events']").contains("['eventId']").isEqualTo("16f1ed75-0bcc-4f0d-a04d-3121798faf99")
+	assertThatJson(parsedJson).array("['events']").contains("['operation']").isEqualTo("EXPORT")
+	assertThatJson(parsedJson).array("['events']").contains("['operation']").isEqualTo("INPUT_PROCESSING")
+	assertThatJson(parsedJson).array("['events']").contains("['eventId']").isEqualTo("3bb4ac82-6652-462f-b6d1-75e424a0024a")
+	assertThatJson(parsedJson).array("['events']").contains("['status']").isEqualTo("OK")
+and:
+	assertThat(parsedJson.read("\$.events[0].operation", String.class)).matches(".+")
+	assertThat(parsedJson.read("\$.events[0].eventId", String.class)).matches("^([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})\$")
+	assertThat(parsedJson.read("\$.events[0].status", String.class)).matches(".+")

As you can see, the assertion is malformed. Only the first element of the array got +asserted. In order to fix this, you should apply the assertion to the whole $.events +collection and assert it with the byCommand(…​) method.

91.6 JAX-RS Support

The Spring Cloud Contract Verifier supports the JAX-RS 2 Client API. The base class needs +to define protected WebTarget webTarget and server initialization. The only option for +testing JAX-RS API is to start a web server. Also, a request with a body needs to have a +content type set. Otherwise, the default of application/octet-stream gets used.

In order to use JAX-RS mode, use the following settings:

testMode == 'JAXRSCLIENT'

The following example shows a generated test API:

'''
+ // when:
+  Response response = webTarget
+    .path("/users")
+    .queryParam("limit", "10")
+    .queryParam("offset", "20")
+    .queryParam("filter", "email")
+    .queryParam("sort", "name")
+    .queryParam("search", "55")
+    .queryParam("age", "99")
+    .queryParam("name", "Denis.Stepanov")
+    .queryParam("email", "bob@email.com")
+    .request()
+    .method("GET");
+
+  String responseAsString = response.readEntity(String.class);
+
+ // then:
+  assertThat(response.getStatus()).isEqualTo(200);
+ // and:
+  DocumentContext parsedJson = JsonPath.parse(responseAsString);
+  assertThatJson(parsedJson).field("['property1']").isEqualTo("a");
+'''

91.7 Async Support

If you’re using asynchronous communication on the server side (your controllers are +returning Callable, DeferredResult, and so on), then, inside your contract, you must +provide a sync() method in the response section. The following code shows an example:

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+    request {
+        method GET()
+        url '/get'
+    }
+    response {
+        status 200
+        body 'Passed'
+        async()
+    }
+}

+

YAML.  +

response:
+    async: true

+

You can also use the fixedDelayMilliseconds method / property to add delay to your stubs.

Groovy DSL.  +

org.springframework.cloud.contract.spec.Contract.make {
+    request {
+        method GET()
+        url '/get'
+    }
+    response {
+        status 200
+        body 'Passed'
+        fixedDelayMilliseconds 1000
+    }
+}

+

YAML.  +

response:
+    fixedDelayMilliseconds: 1000

+

91.8 Working with Context Paths

Spring Cloud Contract supports context paths.

[Important]Important

The only change needed to fully support context paths is the switch on the +PRODUCER side. Also, the autogenerated tests must use EXPLICIT mode. The consumer +side remains untouched. In order for the generated test to pass, you must use EXPLICIT +mode.

Maven.  +

<plugin>
+    <groupId>org.springframework.cloud</groupId>
+    <artifactId>spring-cloud-contract-maven-plugin</artifactId>
+    <version>${spring-cloud-contract.version}</version>
+    <extensions>true</extensions>
+    <configuration>
+        <testMode>EXPLICIT</testMode>
+    </configuration>
+</plugin>

+

Gradle.  +

contracts {
+		testMode = 'EXPLICIT'
+}

+

That way, you generate a test that DOES NOT use MockMvc. It means that you generate +real requests and you need to setup your generated test’s base class to work on a real +socket.

Consider the following contract:

org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method 'GET'
+		url '/my-context-path/url'
+	}
+	response {
+		status 200
+	}
+}

The following example shows how to set up a base class and Rest Assured:

import io.restassured.RestAssured;
+import org.junit.Before;
+import org.springframework.boot.context.embedded.LocalServerPort;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest(classes = ContextPathTestingBaseClass.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+class ContextPathTestingBaseClass {
+
+	@LocalServerPort int port;
+
+	@Before
+	public void setup() {
+		RestAssured.baseURI = "http://localhost";
+		RestAssured.port = this.port;
+	}
+}

If you do it this way:

  • All of your requests in the autogenerated tests are sent to the real endpoint with your +context path included (for example, /my-context-path/url).
  • Your contracts reflect that you have a context path. Your generated stubs also have +that information (for example, in the stubs, you have to call /my-context-path/url).

91.9 Messaging Top-Level Elements

The DSL for messaging looks a little bit different than the one that focuses on HTTP. The +following sections explain the differences:

91.9.1 Output Triggered by a Method

The output message can be triggered by calling a method (such as a Scheduler when a was +started and a message was sent), as shown in the following example:

Groovy DSL.  +

def dsl = Contract.make {
+	// Human readable description
+	description 'Some description'
+	// Label by means of which the output message can be triggered
+	label 'some_label'
+	// input to the contract
+	input {
+		// the contract will be triggered by a method
+		triggeredBy('bookReturnedTriggered()')
+	}
+	// output message of the contract
+	outputMessage {
+		// destination to which the output message will be sent
+		sentTo('output')
+		// the body of the output message
+		body('''{ "bookName" : "foo" }''')
+		// the headers of the output message
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

+

YAML.  +

# Human readable description
+description: Some description
+# Label by means of which the output message can be triggered
+label: some_label
+input:
+  # the contract will be triggered by a method
+  triggeredBy: bookReturnedTriggered()
+# output message of the contract
+outputMessage:
+  # destination to which the output message will be sent
+  sentTo: output
+  # the body of the output message
+  body:
+    bookName: foo
+  # the headers of the output message
+  headers:
+    BOOK-NAME: foo

+

In the previous example case, the output message is sent to output if a method called +bookReturnedTriggered is executed. On the message publisher’s side, we generate a +test that calls that method to trigger the message. On the consumer side, you can use +the some_label to trigger the message.

91.9.2 Output Triggered by a Message

The output message can be triggered by receiving a message, as shown in the following +example:

Groovy DSL.  +

def dsl = Contract.make {
+	description 'Some Description'
+	label 'some_label'
+	// input is a message
+	input {
+		// the message was received from this destination
+		messageFrom('input')
+		// has the following body
+		messageBody([
+		        bookName: 'foo'
+		])
+		// and the following headers
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo('output')
+		body([
+		        bookName: 'foo'
+		])
+		headers {
+			header('BOOK-NAME', 'foo')
+		}
+	}
+}

+

YAML.  +

# Human readable description
+description: Some description
+# Label by means of which the output message can be triggered
+label: some_label
+# input is a message
+input:
+  messageFrom: input
+  # has the following body
+  messageBody:
+    bookName: 'foo'
+  # and the following headers
+  messageHeaders:
+    sample: 'header'
+# output message of the contract
+outputMessage:
+  # destination to which the output message will be sent
+  sentTo: output
+  # the body of the output message
+  body:
+    bookName: foo
+  # the headers of the output message
+  headers:
+    BOOK-NAME: foo

+

In the preceding example, the output message is sent to output if a proper message is +received on the input destination. On the message publisher’s side, the engine +generates a test that sends the input message to the defined destination. On the +consumer side, you can either send a message to the input destination or use a label +(some_label in the example) to trigger the message.

91.9.3 Consumer/Producer

[Important]Important

This section is valid only for Groovy DSL.

In HTTP, you have a notion of client/stub and `server/test notation. You can also +use those paradigms in messaging. In addition, Spring Cloud Contract Verifier also +provides the consumer and producer methods, as presented in the following example +(note that you can use either $ or value methods to provide consumer and producer +parts):

Contract.make {
+	label 'some_label'
+	input {
+		messageFrom value(consumer('jms:output'), producer('jms:input'))
+		messageBody([
+				bookName: 'foo'
+		])
+		messageHeaders {
+			header('sample', 'header')
+		}
+	}
+	outputMessage {
+		sentTo $(consumer('jms:input'), producer('jms:output'))
+		body([
+				bookName: 'foo'
+		])
+	}
+}

91.9.4 Common

In the input or outputMessage section you can call assertThat with the name +of a method (e.g. assertThatMessageIsOnTheQueue()) that you have defined in the +base class or in a static import. Spring Cloud Contract will execute that method +in the generated test.

91.10 Multiple Contracts in One File

You can define multiple contracts in one file. Such a contract might resemble the +following example:

Groovy DSL.  +

import org.springframework.cloud.contract.spec.Contract
+
+[
+        Contract.make {
+            name("should post a user")
+            request {
+                method 'POST'
+                url('/users/1')
+            }
+            response {
+                status 200
+            }
+        },
+        Contract.make {
+            request {
+                method 'POST'
+                url('/users/2')
+            }
+            response {
+                status 200
+            }
+        }
+]

+

YAML.  +

---
+name: should post a user
+request:
+  method: POST
+  url: /users/1
+response:
+  status: 200
+
+---
+request:
+  method: POST
+  url: /users/2
+response:
+  status: 200

+

In the preceding example, one contract has the name field and the other does not. This +leads to generation of two tests that look more or less like this:

package org.springframework.cloud.contract.verifier.tests.com.hello;
+
+import com.example.TestBase;
+import com.jayway.jsonpath.DocumentContext;
+import com.jayway.jsonpath.JsonPath;
+import com.jayway.restassured.module.mockmvc.specification.MockMvcRequestSpecification;
+import com.jayway.restassured.response.ResponseOptions;
+import org.junit.Test;
+
+import static com.jayway.restassured.module.mockmvc.RestAssuredMockMvc.*;
+import static com.toomuchcoding.jsonassert.JsonAssertion.assertThatJson;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class V1Test extends TestBase {
+
+	@Test
+	public void validate_should_post_a_user() throws Exception {
+		// given:
+			MockMvcRequestSpecification request = given();
+
+		// when:
+			ResponseOptions response = given().spec(request)
+					.post("/users/1");
+
+		// then:
+			assertThat(response.statusCode()).isEqualTo(200);
+	}
+
+	@Test
+	public void validate_withList_1() throws Exception {
+		// given:
+			MockMvcRequestSpecification request = given();
+
+		// when:
+			ResponseOptions response = given().spec(request)
+					.post("/users/2");
+
+		// then:
+			assertThat(response.statusCode()).isEqualTo(200);
+	}
+
+}

Notice that, for the contract that has the name field, the generated test method is named +validate_should_post_a_user. For the one that does not have the name, it is called +validate_withList_1. It corresponds to the name of the file WithList.groovy and the +index of the contract in the list.

The generated stubs is shown in the following example:

should post a user.json
+1_WithList.json

As you can see, the first file got the name parameter from the contract. The second +got the name of the contract file (WithList.groovy) prefixed with the index (in this +case, the contract had an index of 1 in the list of contracts in the file).

[Tip]Tip

As you can see, it iss much better if you name your contracts because doing so makes +your tests far more meaningful.

92. Customization

[Important]Important

This section is valid only for Groovy DSL

You can customize the Spring Cloud Contract Verifier by extending the DSL, as shown in +the remainder of this section.

92.1 Extending the DSL

You can provide your own functions to the DSL. The key requirement for this feature is to +maintain the static compatibility. Later in this document, you can see examples of:

  • Creating a JAR with reusable classes.
  • Referencing of these classes in the DSLs.

You can find the full example +here.

92.1.1 Common JAR

The following examples show three classes that can be reused in the DSLs.

PatternUtils contains functions used by both the consumer and the producer.

package com.example;
+
+import java.util.regex.Pattern;
+
+/**
+ * If you want to use {@link Pattern} directly in your tests
+ * then you can create a class resembling this one. It can
+ * contain all the {@link Pattern} you want to use in the DSL.
+ *
+ * <pre>
+ * {@code
+ * request {
+ *     body(
+ *         [ age: $(c(PatternUtils.oldEnough()))]
+ *     )
+ * }
+ * </pre>
+ *
+ * Notice that we're using both {@code $()} for dynamic values
+ * and {@code c()} for the consumer side.
+ *
+ * @author Marcin Grzejszczak
+ */
+//tag::impl[]
+public class PatternUtils {
+
+	public static String tooYoung() {
+		//remove::start[]
+		return "[0-1][0-9]";
+		//remove::end[return]
+	}
+
+	public static Pattern oldEnough() {
+		//remove::start[]
+		return Pattern.compile("[2-9][0-9]");
+		//remove::end[return]
+	}
+
+	/**
+	 * Makes little sense but it's just an example ;)
+	 */
+	public static Pattern ok() {
+		//remove::start[]
+		return Pattern.compile("OK");
+		//remove::end[return]
+	}
+}
+//end::impl[]

ConsumerUtils contains functions used by the consumer.

package com.example;
+
+import org.springframework.cloud.contract.spec.internal.ClientDslProperty;
+
+/**
+ * DSL Properties passed to the DSL from the consumer's perspective.
+ * That means that on the input side {@code Request} for HTTP
+ * or {@code Input} for messaging you can have a regular expression.
+ * On the {@code Response} for HTTP or {@code Output} for messaging
+ * you have to have a concrete value.
+ *
+ * @author Marcin Grzejszczak
+ */
+//tag::impl[]
+public class ConsumerUtils {
+	/**
+	 * Consumer side property. By using the {@link ClientDslProperty}
+	 * you can omit most of boilerplate code from the perspective
+	 * of dynamic values. Example
+	 *
+	 * <pre>
+	 * {@code
+	 * request {
+	 *     body(
+	 *         [ age: $(ConsumerUtils.oldEnough())]
+	 *     )
+	 * }
+	 * </pre>
+	 *
+	 * That way it's in the implementation that we decide what value we will pass to the consumer
+	 * and which one to the producer.
+	 *
+	 * @author Marcin Grzejszczak
+	 */
+	public static ClientDslProperty oldEnough() {
+		//remove::start[]
+		// this example is not the best one and
+		// theoretically you could just pass the regex instead of `ServerDslProperty` but
+		// it's just to show some new tricks :)
+		return new ClientDslProperty(PatternUtils.oldEnough(), 40);
+		//remove::end[return]
+	}
+
+}
+//end::impl[]

ProducerUtils contains functions used by the producer.

package com.example;
+
+import org.springframework.cloud.contract.spec.internal.ServerDslProperty;
+
+/**
+ * DSL Properties passed to the DSL from the producer's perspective.
+ * That means that on the input side {@code Request} for HTTP
+ * or {@code Input} for messaging you have to have a concrete value.
+ * On the {@code Response} for HTTP or {@code Output} for messaging
+ * you can have a regular expression.
+ *
+ * @author Marcin Grzejszczak
+ */
+//tag::impl[]
+public class ProducerUtils {
+
+	/**
+	 * Producer side property. By using the {@link ProducerUtils}
+	 * you can omit most of boilerplate code from the perspective
+	 * of dynamic values. Example
+	 *
+	 * <pre>
+	 * {@code
+	 * response {
+	 *     body(
+	 *         [ status: $(ProducerUtils.ok())]
+	 *     )
+	 * }
+	 * </pre>
+	 *
+	 * That way it's in the implementation that we decide what value we will pass to the consumer
+	 * and which one to the producer.
+	 */
+	public static ServerDslProperty ok() {
+		// this example is not the best one and
+		// theoretically you could just pass the regex instead of `ServerDslProperty` but
+		// it's just to show some new tricks :)
+		return new ServerDslProperty( PatternUtils.ok(), "OK");
+	}
+}
+//end::impl[]

92.1.2 Adding the Dependency to the Project

In order for the plugins and IDE to be able to reference the common JAR classes, you need +to pass the dependency to your project.

92.1.3 Test the Dependency in the Project’s Dependencies

First, add the common jar dependency as a test dependency. Because your contracts files +are available on the test resources path, the common jar classes automatically become +visible in your Groovy files. The following examples show how to test the dependency:

Maven.  +

<dependency>
+	<groupId>com.example</groupId>
+	<artifactId>beer-common</artifactId>
+	<version>${project.version}</version>
+	<scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile("com.example:beer-common:0.0.1.BUILD-SNAPSHOT")

+

92.1.4 Test a Dependency in the Plugin’s Dependencies

Now, you must add the dependency for the plugin to reuse at runtime, as shown in the +following example:

Maven.  +

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example</packageWithBaseClasses>
+		<baseClassMappings>
+			<baseClassMapping>
+				<contractPackageRegex>.*intoxication.*</contractPackageRegex>
+				<baseClassFQN>com.example.intoxication.BeerIntoxicationBase</baseClassFQN>
+			</baseClassMapping>
+		</baseClassMappings>
+	</configuration>
+	<dependencies>
+		<dependency>
+			<groupId>com.example</groupId>
+			<artifactId>beer-common</artifactId>
+			<version>${project.version}</version>
+			<scope>compile</scope>
+		</dependency>
+	</dependencies>
+</plugin>

+

Gradle.  +

classpath "com.example:beer-common:0.0.1.BUILD-SNAPSHOT"

+

92.1.5 Referencing classes in DSLs

You can now reference your classes in your DSL, as shown in the following example:

package contracts.beer.rest
+
+import com.example.ConsumerUtils
+import com.example.ProducerUtils
+import org.springframework.cloud.contract.spec.Contract
+
+Contract.make {
+	description("""
+Represents a successful scenario of getting a beer
+
+```
+given:
+	client is old enough
+when:
+	he applies for a beer
+then:
+	we'll grant him the beer
+```
+
+""")
+	request {
+		method 'POST'
+		url '/check'
+		body(
+				age: $(ConsumerUtils.oldEnough())
+		)
+		headers {
+			contentType(applicationJson())
+		}
+	}
+	response {
+		status 200
+		body("""
+			{
+				"status": "${value(ProducerUtils.ok())}"
+			}
+			""")
+		headers {
+			contentType(applicationJson())
+		}
+	}
+}

93. Using the Pluggable Architecture

You may encounter cases where you have your contracts have been defined in other formats, +such as YAML, RAML or PACT. In those cases, you still want to benefit from the automatic +generation of tests and stubs. You can add your own implementation for generating both +tests and stubs. Also, you can customize the way tests are generated (for example, you +can generate tests for other languages) and the way stubs are generated (for example, you +can generate stubs for other HTTP server implementations).

93.1 Custom Contract Converter

The ContractConverter interface lets you register your own implementation of a contract +structure converter. The following code listing shows the ContractConverter interface:

package org.springframework.cloud.contract.spec
+
+/**
+ * Converter to be used to convert FROM {@link File} TO {@link Contract}
+ * and from {@link Contract} to {@code T}
+ *
+ * @param <T> - type to which we want to convert the contract
+ *
+ * @author Marcin Grzejszczak
+ * @since 1.1.0
+ */
+interface ContractConverter<T> {
+
+	/**
+	 * Should this file be accepted by the converter. Can use the file extension
+	 * to check if the conversion is possible.
+	 *
+	 * @param file - file to be considered for conversion
+	 * @return - {@code true} if the given implementation can convert the file
+	 */
+	boolean isAccepted(File file)
+
+	/**
+	 * Converts the given {@link File} to its {@link Contract} representation
+	 *
+	 * @param file - file to convert
+	 * @return - {@link Contract} representation of the file
+	 */
+	Collection<Contract> convertFrom(File file)
+
+	/**
+	 * Converts the given {@link Contract} to a {@link T} representation
+	 *
+	 * @param contract - the parsed contract
+	 * @return - {@link T} the type to which we do the conversion
+	 */
+	T convertTo(Collection<Contract> contract)
+}

Your implementation must define the condition on which it should start the +conversion. Also, you must define how to perform that conversion in both directions.

[Important]Important

Once you create your implementation, you must create a +/META-INF/spring.factories file in which you provide the fully qualified name of your +implementation.

The following example shows a typical spring.factories file:

org.springframework.cloud.contract.spec.ContractConverter=\
+org.springframework.cloud.contract.verifier.converter.YamlContractConverter

93.1.1 Pact Converter

Spring Cloud Contract includes support for Pact representation of +contracts. Instead of using the Groovy DSL, you can use Pact files. In this section, we +present how to add Pact support for your project.

93.1.2 Pact Contract

Consider following example of a Pact contract, which is a file under the +src/test/resources/contracts folder.

{
+  "provider": {
+    "name": "Provider"
+  },
+  "consumer": {
+    "name": "Consumer"
+  },
+  "interactions": [
+    {
+      "description": "",
+      "request": {
+        "method": "PUT",
+        "path": "/fraudcheck",
+        "headers": {
+          "Content-Type": "application/vnd.fraud.v1+json"
+        },
+        "body": {
+          "clientId": "1234567890",
+          "loanAmount": 99999
+        },
+        "matchingRules": {
+          "$.body.clientId": {
+            "match": "regex",
+            "regex": "[0-9]{10}"
+          }
+        }
+      },
+      "response": {
+        "status": 200,
+        "headers": {
+          "Content-Type": "application/vnd.fraud.v1+json;charset=UTF-8"
+        },
+        "body": {
+          "fraudCheckStatus": "FRAUD",
+          "rejectionReason": "Amount too high"
+        },
+        "matchingRules": {
+          "$.body.fraudCheckStatus": {
+            "match": "regex",
+            "regex": "FRAUD"
+          }
+        }
+      }
+    }
+  ],
+  "metadata": {
+    "pact-specification": {
+      "version": "2.0.0"
+    },
+    "pact-jvm": {
+      "version": "2.4.18"
+    }
+  }
+}

The remainder of this section about using Pact refers to the preceding file.

93.1.3 Pact for Producers

On the producer side, you mustadd two additional dependencies to your plugin +configuration. One is the Spring Cloud Contract Pact support, and the other represents +the current Pact version that you use.

Maven.  +

<plugin>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-maven-plugin</artifactId>
+	<version>${spring-cloud-contract.version}</version>
+	<extensions>true</extensions>
+	<configuration>
+		<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
+	</configuration>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-contract-spec-pact</artifactId>
+			<version>${spring-cloud-contract.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>au.com.dius</groupId>
+			<artifactId>pact-jvm-model</artifactId>
+			<version>2.4.18</version>
+		</dependency>
+	</dependencies>
+</plugin>

+

Gradle.  +

classpath "org.springframework.cloud:spring-cloud-contract-spec-pact:${findProperty('verifierVersion') ?: verifierVersion}"
+classpath 'au.com.dius:pact-jvm-model:2.4.18'

+

When you execute the build of your application, a test will be generated. The generated +test might be as follows:

@Test
+public void validate_shouldMarkClientAsFraud() throws Exception {
+	// given:
+		MockMvcRequestSpecification request = given()
+				.header("Content-Type", "application/vnd.fraud.v1+json")
+				.body("{\"clientId\":\"1234567890\",\"loanAmount\":99999}");
+
+	// when:
+		ResponseOptions response = given().spec(request)
+				.put("/fraudcheck");
+
+	// then:
+		assertThat(response.statusCode()).isEqualTo(200);
+		assertThat(response.header("Content-Type")).isEqualTo("application/vnd.fraud.v1+json;charset=UTF-8");
+	// and:
+		DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
+		assertThatJson(parsedJson).field("rejectionReason").isEqualTo("Amount too high");
+	// and:
+		assertThat(parsedJson.read("$.fraudCheckStatus", String.class)).matches("FRAUD");
+}

The corresponding generated stub might be as follows:

{
+  "uuid" : "996ae5ae-6834-4db6-8fac-358ca187ab62",
+  "request" : {
+    "url" : "/fraudcheck",
+    "method" : "PUT",
+    "headers" : {
+      "Content-Type" : {
+        "equalTo" : "application/vnd.fraud.v1+json"
+      }
+    },
+    "bodyPatterns" : [ {
+      "matchesJsonPath" : "$[?(@.loanAmount == 99999)]"
+    }, {
+      "matchesJsonPath" : "$[?(@.clientId =~ /([0-9]{10})/)]"
+    } ]
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "{\"fraudCheckStatus\":\"FRAUD\",\"rejectionReason\":\"Amount too high\"}",
+    "headers" : {
+      "Content-Type" : "application/vnd.fraud.v1+json;charset=UTF-8"
+    }
+  }
+}

93.1.4 Pact for Consumers

On the producer side, you must add two additional dependencies to your project +dependencies. One is the Spring Cloud Contract Pact support, and the other represents the +current Pact version that you use.

Maven.  +

<dependency>
+	<groupId>org.springframework.cloud</groupId>
+	<artifactId>spring-cloud-contract-spec-pact</artifactId>
+	<scope>test</scope>
+</dependency>
+<dependency>
+	<groupId>au.com.dius</groupId>
+	<artifactId>pact-jvm-model</artifactId>
+	<version>2.4.18</version>
+	<scope>test</scope>
+</dependency>

+

Gradle.  +

testCompile "org.springframework.cloud:spring-cloud-contract-spec-pact"
+testCompile 'au.com.dius:pact-jvm-model:2.4.18'

+

93.2 Using the Custom Test Generator

If you want to generate tests for languages other than Java or you are not happy with the +way the verifier builds Java tests, you can register your own implementation.

The SingleTestGenerator interface lets you register your own implementation. The +following code listing shows the SingleTestGenerator interface:

package org.springframework.cloud.contract.verifier.builder
+
+import org.springframework.cloud.contract.verifier.config.ContractVerifierConfigProperties
+import org.springframework.cloud.contract.verifier.file.ContractMetadata
+/**
+ * Builds a single test.
+ *
+ * @since 1.1.0
+ */
+interface SingleTestGenerator {
+
+	/**
+	 * Creates contents of a single test class in which all test scenarios from
+	 * the contract metadata should be placed.
+	 *
+	 * @param properties - properties passed to the plugin
+	 * @param listOfFiles - list of parsed contracts with additional metadata
+	 * @param className - the name of the generated test class
+	 * @param classPackage - the name of the package in which the test class should be stored
+	 * @param includedDirectoryRelativePath - relative path to the included directory
+	 * @return contents of a single test class
+	 */
+	String buildClass(ContractVerifierConfigProperties properties, Collection<ContractMetadata> listOfFiles,
+					  String className, String classPackage, String includedDirectoryRelativePath)
+
+	/**
+	 * Extension that should be appended to the generated test class. E.g. {@code .java} or {@code .php}
+	 *
+	 * @param properties - properties passed to the plugin
+	 */
+	String fileExtension(ContractVerifierConfigProperties properties)
+}

Again, you must provide a spring.factories file, such as the one shown in the following +example:

org.springframework.cloud.contract.verifier.builder.SingleTestGenerator=/
+com.example.MyGenerator

93.3 Using the Custom Stub Generator

If you want to generate stubs for stub servers other than WireMock, you can plug in your +own implementation of the StubGenerator interface. The following code listing shows the +StubGenerator interface:

package org.springframework.cloud.contract.verifier.converter
+
+import groovy.transform.CompileStatic
+import org.springframework.cloud.contract.spec.Contract
+import org.springframework.cloud.contract.verifier.file.ContractMetadata
+
+/**
+ * Converts contracts into their stub representation.
+ *
+ * @since 1.1.0
+ */
+@CompileStatic
+interface StubGenerator {
+
+	/**
+	 * Returns {@code true} if the converter can handle the file to convert it into a stub.
+	 */
+	boolean canHandleFileName(String fileName)
+
+	/**
+	 * Returns the collection of converted contracts into stubs. One contract can
+	 * result in multiple stubs.
+	 */
+	Map<Contract, String> convertContents(String rootName, ContractMetadata content)
+
+	/**
+	 * Returns the name of the converted stub file. If you have multiple contracts
+	 * in a single file then a prefix will be added to the generated file. If you
+	 * provide the {@link Contract#name} field then that field will override the
+	 * generated file name.
+	 *
+	 * Example: name of file with 2 contracts is {@code foo.groovy}, it will be
+	 * converted by the implementation to {@code foo.json}. The recursive file
+	 * converter will create two files {@code 0_foo.json} and {@code 1_foo.json}
+	 */
+	String generateOutputFileNameForInput(String inputFileName)
+}

Again, you must provide a spring.factories file, such as the one shown in the following +example:

# Stub converters
+org.springframework.cloud.contract.verifier.converter.StubGenerator=\
+org.springframework.cloud.contract.verifier.wiremock.DslToWireMockClientConverter

The default implementation is the WireMock stub generation.

[Tip]Tip

You can provide multiple stub generator implementations. For example, from a single +DSL, you can produce both WireMock stubs and Pact files.

93.4 Using the Custom Stub Runner

If you decide to use a custom stub generation, you also need a custom way of running +stubs with your different stub provider.

Assume that you use Moco to build your stubs and that +you have written a stub generator and placed your stubs in a JAR file.

In order for Stub Runner to know how to run your stubs, you have to define a custom +HTTP Stub server implementation, which might resemble the following example:

package org.springframework.cloud.contract.stubrunner.provider.moco
+
+import com.github.dreamhead.moco.bootstrap.arg.HttpArgs
+import com.github.dreamhead.moco.runner.JsonRunner
+import com.github.dreamhead.moco.runner.RunnerSetting
+import groovy.util.logging.Slf4j
+import org.springframework.cloud.contract.stubrunner.HttpServerStub
+import org.springframework.util.SocketUtils
+
+@Slf4j
+class MocoHttpServerStub implements HttpServerStub {
+
+	private boolean started
+	private JsonRunner runner
+	private int port
+
+	@Override
+	int port() {
+		if (!isRunning()) {
+			return -1
+		}
+		return port
+	}
+
+	@Override
+	boolean isRunning() {
+		return started
+	}
+
+	@Override
+	HttpServerStub start() {
+		return start(SocketUtils.findAvailableTcpPort())
+	}
+
+	@Override
+	HttpServerStub start(int port) {
+		this.port = port
+		return this
+	}
+
+	@Override
+	HttpServerStub stop() {
+		if (!isRunning()) {
+			return this
+		}
+		this.runner.stop()
+		return this
+	}
+
+	@Override
+	HttpServerStub registerMappings(Collection<File> stubFiles) {
+		List<RunnerSetting> settings = stubFiles.findAll { it.name.endsWith("json") }
+				.collect {
+			log.info("Trying to parse [{}]", it.name)
+			try {
+				return RunnerSetting.aRunnerSetting().withStream(it.newInputStream()).build()
+			} catch (Exception e) {
+				log.warn("Exception occurred while trying to parse file [{}]", it.name, e)
+				return null
+			}
+		}.findAll { it }
+		this.runner = JsonRunner.newJsonRunnerWithSetting(settings,
+				HttpArgs.httpArgs().withPort(this.port).build())
+		this.runner.run()
+		this.started = true
+		return this
+	}
+
+	@Override
+	String registeredMappings() {
+		return ""
+	}
+
+	@Override
+	boolean isAccepted(File file) {
+		return file.name.endsWith(".json")
+	}
+}

Then, you can register it in your spring.factories file, as shown in the following +example:

org.springframework.cloud.contract.stubrunner.HttpServerStub=\
+org.springframework.cloud.contract.stubrunner.provider.moco.MocoHttpServerStub

Now you can run stubs with Moco.

[Important]Important

If you do not provide any implementation, then the default (WireMock) +implementation is used. If you provide more than one, the first one on the list is used.

93.5 Using the Custom Stub Downloader

You can customize the way your stubs are downloaded by creating an implementation of the +StubDownloaderBuilder interface, as shown in the following example:

package com.example;
+
+class CustomStubDownloaderBuilder implements StubDownloaderBuilder {
+
+	@Override
+	public StubDownloader build(final StubRunnerOptions stubRunnerOptions) {
+		return new StubDownloader() {
+			@Override
+			public Map.Entry<StubConfiguration, File> downloadAndUnpackStubJar(
+					StubConfiguration config) {
+				File unpackedStubs = retrieveStubs();
+				return new AbstractMap.SimpleEntry<>(
+						new StubConfiguration(config.getGroupId(), config.getArtifactId(), version,
+								config.getClassifier()), unpackedStubs);
+			}
+
+			File retrieveStubs() {
+			    // here goes your custom logic to provide a folder where all the stubs reside
+			}
+}

Then you can register it in your spring.factories file, as shown in the following +example:

# Example of a custom Stub Downloader Provider
+org.springframework.cloud.contract.stubrunner.StubDownloaderBuilder=\
+com.example.CustomStubDownloaderBuilder

Now you can pick a folder with the source of your stubs.

[Important]Important

If you do not provide any implementation, then the default is used. +If you use the repositoryRoot property or the workOffline flag, then an Aether-based +implementation that downloads stubs from a remote repository is used. If you do not +provide these values, the ClasspathStubProvider (which will scan the classpath) is +used. If you provide more than one, then the first one on the list is used.

94. Spring Cloud Contract WireMock

The Spring Cloud Contract WireMock modules let you use WireMock in a +Spring Boot application. Check out the +samples +for more details.

If you have a Spring Boot application that uses Tomcat as an embedded server (which is +the default with spring-boot-starter-web), you can add +spring-cloud-starter-contract-stub-runner to your classpath and add @AutoConfigureWireMock in +order to be able to use Wiremock in your tests. Wiremock runs as a stub server and you +can register stub behavior using a Java API or via static JSON declarations as part of +your test. The following code shows an example:

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@AutoConfigureWireMock(port = 0)
+public class WiremockForDocsTests {
+	// A service that calls out over HTTP
+	@Autowired private Service service;
+
+	// Using the WireMock APIs in the normal way:
+	@Test
+	public void contextLoads() throws Exception {
+		// Stubbing WireMock
+		stubFor(get(urlEqualTo("/resource"))
+				.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
+		// We're asserting if WireMock responded properly
+		assertThat(this.service.go()).isEqualTo("Hello World!");
+	}
+
+}

To start the stub server on a different port use (for example), +@AutoConfigureWireMock(port=9999). For a random port, use a value of 0. The stub +server port can be bound in the test application context with the "wiremock.server.port" +property. Using @AutoConfigureWireMock adds a bean of type WiremockConfiguration to +your test application context, where it will be cached in between methods and classes +having the same context, the same as for Spring integration tests.

94.1 Registering Stubs Automatically

If you use @AutoConfigureWireMock, it registers WireMock JSON stubs from the file +system or classpath (by default, from file:src/test/resources/mappings). You can +customize the locations using the stubs attribute in the annotation, which can be an +Ant-style resource pattern or a directory. In the case of a directory, */.json is +appended. The following code shows an example:

@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureWireMock(stubs="classpath:/stubs")
+public class WiremockImportApplicationTests {
+
+	@Autowired
+	private Service service;
+
+	@Test
+	public void contextLoads() throws Exception {
+		assertThat(this.service.go()).isEqualTo("Hello World!");
+	}
+
+}
[Note]Note

Actually, WireMock always loads mappings from src/test/resources/mappings as +well as the custom locations in the stubs attribute. To change this behavior, you can +also specify a files root as described in the next section of this document.

94.2 Using Files to Specify the Stub Bodies

WireMock can read response bodies from files on the classpath or the file system. In that +case, you can see in the JSON DSL that the response has a bodyFileName instead of a +(literal) body. The files are resolved relative to a root directory (by default, +src/test/resources/__files). To customize this location you can set the files +attribute in the @AutoConfigureWireMock annotation to the location of the parent +directory (in other words, __files is a subdirectory). You can use Spring resource +notation to refer to file:…​ or classpath:…​ locations. Generic URLs are not +supported. A list of values can be given, in which case WireMock resolves the first file +that exists when it needs to find a response body.

[Note]Note

When you configure the files root, it also affects the +automatic loading of stubs, because they come from the root location +in a subdirectory called "mappings". The value of files has no +effect on the stubs loaded explicitly from the stubs attribute.

94.3 Alternative: Using JUnit Rules

For a more conventional WireMock experience, you can use JUnit @Rules to start and stop +the server. To do so, use the WireMockSpring convenience class to obtain an Options +instance, as shown in the following example:

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+public class WiremockForDocsClassRuleTests {
+
+	// Start WireMock on some dynamic port
+	// for some reason `dynamicPort()` is not working properly
+	@ClassRule
+	public static WireMockClassRule wiremock = new WireMockClassRule(
+			WireMockSpring.options().dynamicPort());
+	// A service that calls out over HTTP to localhost:${wiremock.port}
+	@Autowired
+	private Service service;
+
+	// Using the WireMock APIs in the normal way:
+	@Test
+	public void contextLoads() throws Exception {
+		// Stubbing WireMock
+		wiremock.stubFor(get(urlEqualTo("/resource"))
+				.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
+		// We're asserting if WireMock responded properly
+		assertThat(this.service.go()).isEqualTo("Hello World!");
+	}
+
+}

The @ClassRule means that the server shuts down after all the methods in this class +have been run.

94.4 Relaxed SSL Validation for Rest Template

WireMock lets you stub a "secure" server with an "https" URL protocol. If your +application wants to contact that stub server in an integration test, it will find that +the SSL certificates are not valid (the usual problem with self-installed certificates). +The best option is often to re-configure the client to use "http". If that’s not an +option, you can ask Spring to configure an HTTP client that ignores SSL validation errors +(do so only for tests, of course).

To make this work with minimum fuss, you need to be using the Spring Boot +RestTemplateBuilder in your app, as shown in the following example:

@Bean
+public RestTemplate restTemplate(RestTemplateBuilder builder) {
+	return builder.build();
+}

You need RestTemplateBuilder because the builder is passed through callbacks to +initialize it, so the SSL validation can be set up in the client at that point. This +happens automatically in your test if you are using the @AutoConfigureWireMock +annotation or the stub runner. If you use the JUnit @Rule approach, you need to add the +@AutoConfigureHttpClient annotation as well, as shown in the following example:

@RunWith(SpringRunner.class)
+@SpringBootTest("app.baseUrl=https://localhost:6443")
+@AutoConfigureHttpClient
+public class WiremockHttpsServerApplicationTests {
+
+	@ClassRule
+	public static WireMockClassRule wiremock = new WireMockClassRule(
+			WireMockSpring.options().httpsPort(6443));
+...
+}

If you are using spring-boot-starter-test, you have the Apache HTTP client on the +classpath and it is selected by the RestTemplateBuilder and configured to ignore SSL +errors. If you use the default java.net client, you do not need the annotation (but it +won’t do any harm). There is no support currently for other clients, but it may be added +in future releases.

94.5 WireMock and Spring MVC Mocks

Spring Cloud Contract provides a convenience class that can load JSON WireMock stubs into +a Spring MockRestServiceServer. The following code shows an example:

@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.NONE)
+public class WiremockForDocsMockServerApplicationTests {
+
+	@Autowired
+	private RestTemplate restTemplate;
+
+	@Autowired
+	private Service service;
+
+	@Test
+	public void contextLoads() throws Exception {
+		// will read stubs classpath
+		MockRestServiceServer server = WireMockRestServiceServer.with(this.restTemplate)
+				.baseUrl("https://example.org").stubs("classpath:/stubs/resource.json")
+				.build();
+		// We're asserting if WireMock responded properly
+		assertThat(this.service.go()).isEqualTo("Hello World");
+		server.verify();
+	}
+}

The baseUrl value is prepended to all mock calls, and the stubs() method takes a stub +path resource pattern as an argument. In the preceding example, the stub defined at +/stubs/resource.json is loaded into the mock server. If the RestTemplate is asked to +visit https://example.org/, it gets the responses as being declared at that URL. More +than one stub pattern can be specified, and each one can be a directory (for a recursive +list of all ".json"), a fixed filename (as in the example above), or an Ant-style +pattern. The JSON format is the normal WireMock format, which you can read about in the +WireMock website.

Currently, the Spring Cloud Contract Verifier supports Tomcat, Jetty, and Undertow as +Spring Boot embedded servers, and Wiremock itself has "native" support for a particular +version of Jetty (currently 9.2). To use the native Jetty, you need to add the native +Wiremock dependencies and exclude the Spring Boot container (if there is one).

94.6 Customization of WireMock configuration

You can register a bean of org.springframework.cloud.contract.wiremock.WireMockConfigurationCustomizer type +in order to customize the WireMock configuration (e.g. add custom transformers). +Example:

		@Bean WireMockConfigurationCustomizer optionsCustomizer() {
+			return new WireMockConfigurationCustomizer() {
+				@Override public void customize(WireMockConfiguration options) {
+// perform your customization here
+				}
+			};
+		}

94.7 Generating Stubs using REST Docs

Spring REST Docs can be used to generate +documentation (for example in Asciidoctor format) for an HTTP API with Spring MockMvc or +Rest Assured. At the same time that you generate documentation for your API, you can also +generate WireMock stubs by using Spring Cloud Contract WireMock. To do so, write your +normal REST Docs test cases and use @AutoConfigureRestDocs to have stubs be +automatically generated in the REST Docs output directory. The following code shows an +example:

@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureRestDocs(outputDir = "target/snippets")
+@AutoConfigureMockMvc
+public class ApplicationTests {
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@Test
+	public void contextLoads() throws Exception {
+		mockMvc.perform(get("/resource"))
+				.andExpect(content().string("Hello World"))
+				.andDo(document("resource"));
+	}
+}

This test generates a WireMock stub at "target/snippets/stubs/resource.json". It matches +all GET requests to the "/resource" path.

Without any additional configuration, this tests creates a stub with a request matcher +for the HTTP method and all headers except "host" and "content-length". To match the +request more precisely (for example, to match the body of a POST or PUT), we need to +explicitly create a request matcher. Doing so has two effects:

  • Creating a stub that matches only in the way you specify.
  • Asserting that the request in the test case also matches the same conditions.

The main entry point for this feature is WireMockRestDocs.verify(), which can be used +as a substitute for the document() convenience method, as shown in the following +example:

@RunWith(SpringRunner.class)
+@SpringBootTest
+@AutoConfigureRestDocs(outputDir = "target/snippets")
+@AutoConfigureMockMvc
+public class ApplicationTests {
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@Test
+	public void contextLoads() throws Exception {
+		mockMvc.perform(post("/resource")
+                .content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
+				.andExpect(status().isOk())
+				.andDo(verify().jsonPath("$.id")
+                        .stub("resource"));
+	}
+}

This contract specifies that any valid POST with an "id" field receives the response +defined in this test. You can chain together calls to .jsonPath() to add additional +matchers. If JSON Path is unfamiliar, The JayWay +documentation can help you get up to speed.

Instead of the jsonPath and contentType convenience methods, you can also use the +WireMock APIs to verify that the request matches the created stub, as shown in the +following example:

@Test
+public void contextLoads() throws Exception {
+	mockMvc.perform(post("/resource")
+               .content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
+			.andExpect(status().isOk())
+			.andDo(verify()
+					.wiremock(WireMock.post(
+						urlPathEquals("/resource"))
+						.withRequestBody(matchingJsonPath("$.id"))
+                       .stub("post-resource"));
+}

The WireMock API is rich. You can match headers, query parameters, and request body by +regex as well as by JSON path. These features can be used to create stubs with a wider +range of parameters. The above example generates a stub resembling the following example:

post-resource.json.  +

{
+  "request" : {
+    "url" : "/resource",
+    "method" : "POST",
+    "bodyPatterns" : [ {
+      "matchesJsonPath" : "$.id"
+    }]
+  },
+  "response" : {
+    "status" : 200,
+    "body" : "Hello World",
+    "headers" : {
+      "X-Application-Context" : "application:-1",
+      "Content-Type" : "text/plain"
+    }
+  }
+}

+

[Note]Note

You can use either the wiremock() method or the jsonPath() and contentType() +methods to create request matchers, but you can’t use both approaches.

On the consumer side, you can make the resource.json generated earlier in this section +available on the classpath (by +publishing +stubs as JARs, for example). After that, you can create a stub using WireMock in a +number of different ways, including by using +@AutoConfigureWireMock(stubs="classpath:resource.json"), as described earlier in this +document.

94.8 Generating Contracts by Using REST Docs

You can also generate Spring Cloud Contract DSL files and documentation with Spring REST +Docs. If you do so in combination with Spring Cloud WireMock, you get both the contracts +and the stubs.

Why would you want to use this feature? Some people in the community asked questions +about a situation in which they would like to move to DSL-based contract definition, +but they already have a lot of Spring MVC tests. Using this feature lets you generate +the contract files that you can later modify and move to folders (defined in your +configuration) so that the plugin finds them.

[Tip]Tip

You might wonder why this functionality is in the WireMock module. The functionality +is there because it makes sense to generate both the contracts and the stubs.

Consider the following test:

		this.mockMvc.perform(post("/foo")
+					.accept(MediaType.APPLICATION_PDF)
+					.accept(MediaType.APPLICATION_JSON)
+					.contentType(MediaType.APPLICATION_JSON)
+					.content("{\"foo\": 23, \"bar\" : \"baz\" }"))
+				.andExpect(status().isOk())
+				.andExpect(content().string("bar"))
+				// first WireMock
+				.andDo(WireMockRestDocs.verify()
+						.jsonPath("$[?(@.foo >= 20)]")
+						.jsonPath("$[?(@.bar in ['baz','bazz','bazzz'])]")
+						.contentType(MediaType.valueOf("application/json"))
+						.stub("shouldGrantABeerIfOldEnough"))
+				// then Contract DSL documentation
+				.andDo(document("index", SpringCloudContractRestDocs.dslContract()));

The preceding test creates the stub presented in the previous section, generating both +the contract and a documentation file.

The contract is called index.groovy and might look like the following example:

import org.springframework.cloud.contract.spec.Contract
+
+Contract.make {
+    request {
+        method 'POST'
+        url '/foo'
+        body('''
+            {"foo": 23 }
+        ''')
+        headers {
+            header('''Accept''', '''application/json''')
+            header('''Content-Type''', '''application/json''')
+        }
+    }
+    response {
+        status 200
+        body('''
+        bar
+        ''')
+        headers {
+            header('''Content-Type''', '''application/json;charset=UTF-8''')
+            header('''Content-Length''', '''3''')
+        }
+        testMatchers {
+            jsonPath('$[?(@.foo >= 20)]', byType())
+        }
+    }
+}

The generated document (formatted in Asciidoc in this case) contains a formatted +contract. The location of this file would be index/dsl-contract.adoc.

95. Migrations

This section covers migrating from one version of Spring Cloud Contract Verifier to the +next version. It covers the following versions upgrade paths:

95.1 1.0.x → 1.1.x

This section covers upgrading from version 1.0 to version 1.1.

95.1.1 New structure of generated stubs

In 1.1.x we have introduced a change to the structure of generated stubs. If you have +been using the @AutoConfigureWireMock notation to use the stubs from the classpath, +it no longer works. The following example shows how the @AutoConfigureWireMock notation +used to work:

@AutoConfigureWireMock(stubs = "classpath:/customer-stubs/mappings", port = 8084)

You must either change the location of the stubs to: +classpath:…​/META-INF/groupId/artifactId/version/mappings or use the new +classpath-based @AutoConfigureStubRunner, as shown in the following example:

@AutoConfigureWireMock(stubs = "classpath:customer-stubs/META-INF/travel.components/customer-contract/1.0.2-SNAPSHOT/mappings/", port = 8084)

If you do not want to use @AutoConfigureStubRunner and you want to remain with the old +structure, set your plugin tasks accordingly. The following example would work for the +structure presented in the previous snippet.

Maven.  +

<!-- start of pom.xml -->
+
+<properties>
+    <!-- we don't want the verifier to do a jar for us -->
+    <spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip>
+</properties>
+
+<!-- ... -->
+
+<!-- You need to set up the assembly plugin -->
+<build>
+    <plugins>
+        <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-assembly-plugin</artifactId>
+            <executions>
+                <execution>
+                    <id>stub</id>
+                    <phase>prepare-package</phase>
+                    <goals>
+                        <goal>single</goal>
+                    </goals>
+                    <inherited>false</inherited>
+                    <configuration>
+                        <attach>true</attach>
+                        <descriptor>$../../../../src/assembly/stub.xml</descriptor>
+                    </configuration>
+                </execution>
+            </executions>
+        </plugin>
+    </plugins>
+</build>
+<!-- end of pom.xml -->
+
+<!-- start of stub.xml-->
+
+<assembly
+	xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	<id>stubs</id>
+	<formats>
+		<format>jar</format>
+	</formats>
+	<includeBaseDirectory>false</includeBaseDirectory>
+	<fileSets>
+		<fileSet>
+			<directory>${project.build.directory}/snippets/stubs</directory>
+			<outputDirectory>customer-stubs/mappings</outputDirectory>
+			<includes>
+				<include>**/*</include>
+			</includes>
+		</fileSet>
+		<fileSet>
+			<directory>$../../../../src/test/resources/contracts</directory>
+			<outputDirectory>customer-stubs/contracts</outputDirectory>
+			<includes>
+				<include>**/*.groovy</include>
+			</includes>
+		</fileSet>
+	</fileSets>
+</assembly>
+
+<!-- end of stub.xml-->

+

Gradle.  +

task copyStubs(type: Copy, dependsOn: 'generateWireMockClientStubs') {
+//    Preserve directory structure from 1.0.X of spring-cloud-contract
+    from "${project.buildDir}/resources/main/customer-stubs/META-INF/${project.group}/${project.name}/${project.version}"
+    into "${project.buildDir}/resources/main/customer-stubs"
+}

+

95.2 1.1.x → 1.2.x

This section covers upgrading from version 1.1 to version 1.2.

95.2.1 Custom HttpServerStub

HttpServerStub includes a method that was not in version 1.1. The method is +String registeredMappings() If you have classes that implement HttpServerStub, you +now have to implement the registeredMappings() method. It should return a String +representing all mappings available in a single HttpServerStub.

See issue 355 for more +detail.

95.2.2 New packages for generated tests

The flow for setting the generated tests package name will look like this:

  • Set basePackageForTests
  • If basePackageForTests was not set, pick the package from baseClassForTests
  • If baseClassForTests was not set, pick packageWithBaseClasses
  • If nothing got set, pick the default value: +org.springframework.cloud.contract.verifier.tests

See issue 260 for more +detail.

95.2.3 New Methods in TemplateProcessor

In order to add support for fromRequest.path, the following methods had to be added to the +TemplateProcessor interface:

  • path()
  • path(int index)

See issue 388 for more +detail.

95.2.4 RestAssured 3.0

Rest Assured, used in the generated test classes, got bumped to 3.0. If +you manually set versions of Spring Cloud Contract and the release train +you might see the following exception:

Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:testCompile (default-testCompile) on project some-project: Compilation failure: Compilation failure:
+[ERROR] /some/path/SomeClass.java:[4,39] package com.jayway.restassured.response does not exist

This exception will occur due to the fact that the tests got generated with +an old version of plugin and at test execution time you have an incompatible +version of the release train (and vice versa).

Done via issue 267

96. Links

The following links may be helpful when working with Spring Cloud Contract Verifier:

Part XIV. Spring Cloud Vault

© 2016-2017 The original authors.

[Note]Note

Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.

Spring Cloud Vault Config provides client-side support for externalized configuration in a distributed system. With HashiCorp’s Vault you have a central place to manage external secret properties for applications across all environments. Vault can manage static and dynamic secrets such as username/password for remote applications/resources and provide credentials for external services such as MySQL, PostgreSQL, Apache Cassandra, MongoDB, Consul, AWS and more.

97. Quick Start

Prerequisites

To get started with Vault and this guide you need a +*NIX-like operating systems that provides:

  • wget, openssl and unzip
  • at least Java 7 and a properly configured JAVA_HOME environment variable

Install Vault

$ src/test/bash/install_vault.sh

Create SSL certificates for Vault

$ src/test/bash/create_certificates.sh
[Note]Note

create_certificates.sh creates certificates in work/ca and a JKS truststore work/keystore.jks. If you want to run Spring Cloud Vault using this quickstart guide you need to configure the truststore the spring.cloud.vault.ssl.trust-store property to file:work/keystore.jks.

Start Vault server

$ src/test/bash/local_run_vault.sh

Vault is started listening on 0.0.0.0:8200 using the inmem storage and +https. +Vault is sealed and not initialized when starting up.

[Note]Note

If you want to run tests, leave Vault uninitialized. The tests will +initialize Vault and create a root token 00000000-0000-0000-0000-000000000000.

If you want to use Vault for your application or give it a try then you need to initialize it first.

$ export VAULT_ADDR="https://localhost:8200"
+$ export VAULT_SKIP_VERIFY=true # Don't do this for production
+$ vault init

You should see something like:

Key 1: 7149c6a2e16b8833f6eb1e76df03e47f6113a3288b3093faf5033d44f0e70fe701
+Key 2: 901c534c7988c18c20435a85213c683bdcf0efcd82e38e2893779f152978c18c02
+Key 3: 03ff3948575b1165a20c20ee7c3e6edf04f4cdbe0e82dbff5be49c63f98bc03a03
+Key 4: 216ae5cc3ddaf93ceb8e1d15bb9fc3176653f5b738f5f3d1ee00cd7dccbe926e04
+Key 5: b2898fc8130929d569c1677ee69dc5f3be57d7c4b494a6062693ce0b1c4d93d805
+Initial Root Token: 19aefa97-cccc-bbbb-aaaa-225940e63d76
+
+Vault initialized with 5 keys and a key threshold of 3. Please
+securely distribute the above keys. When the Vault is re-sealed,
+restarted, or stopped, you must provide at least 3 of these keys
+to unseal it again.
+
+Vault does not store the master key. Without at least 3 keys,
+your Vault will remain permanently sealed.

Vault will initialize and return a set of unsealing keys and the root token. +Pick 3 keys and unseal Vault. Store the Vault token in the VAULT_TOKEN + environment variable.

$ vault unseal (Key 1)
+$ vault unseal (Key 2)
+$ vault unseal (Key 3)
+$ export VAULT_TOKEN=(Root token)
+# Required to run Spring Cloud Vault tests after manual initialization
+$ vault token-create -id="00000000-0000-0000-0000-000000000000" -policy="root"

Spring Cloud Vault accesses different resources. By default, the secret +backend is enabled which accesses secret config settings via JSON endpoints.

The HTTP service has resources in the form:

/secret/{application}/{profile}
+/secret/{application}
+/secret/{defaultContext}/{profile}
+/secret/{defaultContext}

where the "application" is injected as the spring.application.name in the +SpringApplication (i.e. what is normally "application" in a regular +Spring Boot app), "profile" is an active profile (or comma-separated +list of properties). Properties retrieved from Vault will be used "as-is" +without further prefixing of the property names.

98. Client Side Usage

To use these features in an application, just build it as a Spring +Boot application that depends on spring-cloud-vault-config (e.g. see +the test cases). Example Maven configuration:

Example 98.1. pom.xml

<parent>
+    <groupId>org.springframework.boot</groupId>
+    <artifactId>spring-boot-starter-parent</artifactId>
+    <version>1.5.4.RELEASE</version>
+    <relativePath /> <!-- lookup parent from repository -->
+</parent>
+
+<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-starter-vault-config</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-test</artifactId>
+        <scope>test</scope>
+    </dependency>
+</dependencies>
+
+<build>
+    <plugins>
+        <plugin>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-maven-plugin</artifactId>
+        </plugin>
+    </plugins>
+</build>
+
+<!-- repositories also needed for snapshots and milestones -->

Then you can create a standard Spring Boot application, like this simple HTTP server:

@SpringBootApplication
+@RestController
+public class Application {
+
+    @RequestMapping("/")
+    public String home() {
+        return "Hello World!";
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}

When it runs it will pick up the external configuration from the +default local Vault server on port 8200 if it is running. To modify +the startup behavior you can change the location of the Vault server +using bootstrap.properties (like application.properties but for +the bootstrap phase of an application context), e.g.

Example 98.2. bootstrap.yml

spring.cloud.vault:
+    host: localhost
+    port: 8200
+    scheme: https
+    uri: https://localhost:8200
+    connection-timeout: 5000
+    read-timeout: 15000
+    config:
+        order: -10

  • host sets the hostname of the Vault host. The host name will be used +for SSL certificate validation
  • port sets the Vault port
  • scheme setting the scheme to http will use plain HTTP. +Supported schemes are http and https.
  • uri configure the Vault endpoint with an URI. Takes precedence over host/port/scheme configuration
  • connection-timeout sets the connection timeout in milliseconds
  • read-timeout sets the read timeout in milliseconds
  • config.order sets the order for the property source

Enabling further integrations requires additional dependencies and +configuration. Depending on how you have set up Vault you might need +additional configuration like +SSL and +authentication.

If the application imports the spring-boot-starter-actuator project, the +status of the vault server will be available via the /health endpoint.

The vault health indicator can be enabled or disabled through the +property health.vault.enabled (default true).

98.1 Authentication

Vault requires an authentication mechanism to authorize client requests.

Spring Cloud Vault supports multiple authentication mechanisms to authenticate applications with Vault.

For a quickstart, use the root token printed by the Vault initialization.

Example 98.3. bootstrap.yml

spring.cloud.vault:
+    token: 19aefa97-cccc-bbbb-aaaa-225940e63d76

[Warning]Warning

Consider carefully your security requirements. Static token authentication is fine if you want quickly get started with Vault, but a static token is not protected any further. Any disclosure to unintended parties allows Vault use with the associated token roles.

99. Authentication methods

Different organizations have different requirements for security +and authentication. Vault reflects that need by shipping multiple authentication +methods. Spring Cloud Vault supports token and AppId authentication.

99.1 Token authentication

Tokens are the core method for authentication within Vault. +Token authentication requires a static token to be provided using the +Bootstrap Application Context.

[Note]Note

Token authentication is the default authentication method. +If a token is disclosed an unintended party gains access to Vault and +can access secrets for the intended client.

Example 99.1. bootstrap.yml

spring.cloud.vault:
+    authentication: TOKEN
+    token: 00000000-0000-0000-0000-000000000000

  • authentication setting this value to TOKEN selects the Token +authentication method
  • token sets the static token to use

See also: Vault Documentation: Tokens

99.2 AppId authentication

Vault supports AppId +authentication that consists of two hard to guess tokens. The AppId +defaults to spring.application.name that is statically configured. +The second token is the UserId which is a part determined by the application, +usually related to the runtime environment. IP address, Mac address or a +Docker container name are good examples. Spring Cloud Vault Config supports +IP address, Mac address and static UserId’s (e.g. supplied via System properties). +The IP and Mac address are represented as Hex-encoded SHA256 hash.

IP address-based UserId’s use the local host’s IP address.

Example 99.2. bootstrap.yml using SHA256 IP-Address UserId’s

spring.cloud.vault:
+    authentication: APPID
+    app-id:
+        user-id: IP_ADDRESS

  • authentication setting this value to APPID selects the AppId +authentication method
  • app-id-path sets the path of the AppId mount to use
  • user-id sets the UserId method. Possible values are IP_ADDRESS, +MAC_ADDRESS or a class name implementing a custom AppIdUserIdMechanism

The corresponding command to generate the IP address UserId from a command line is:

$ echo -n 192.168.99.1 | sha256sum
[Note]Note

Including the line break of echo leads to a different hash value +so make sure to include the -n flag.

Mac address-based UserId’s obtain their network device from the +localhost-bound device. The configuration also allows specifying +a network-interface hint to pick the right device. The value of +network-interface is optional and can be either an interface +name or interface index (0-based).

Example 99.3. bootstrap.yml using SHA256 Mac-Address UserId’s

spring.cloud.vault:
+    authentication: APPID
+    app-id:
+        user-id: MAC_ADDRESS
+        network-interface: eth0

  • network-interface sets network interface to obtain the physical address

The corresponding command to generate the IP address UserId from a command line is:

$ echo -n 0AFEDE1234AC | sha256sum
[Note]Note

The Mac address is specified uppercase and without colons. +Including the line break of echo leads to a different hash value +so make sure to include the -n flag.

99.2.1 Custom UserId

The UserId generation is an open mechanism. You can set +spring.cloud.vault.app-id.user-id to any string and the configured +value will be used as static UserId.

A more advanced approach lets you set spring.cloud.vault.app-id.user-id to a +classname. This class must be on your classpath and must implement +the org.springframework.cloud.vault.AppIdUserIdMechanism interface +and the createUserId method. Spring Cloud Vault will obtain the UserId +by calling createUserId each time it authenticates using AppId to +obtain a token.

Example 99.4. bootstrap.yml

spring.cloud.vault:
+    authentication: APPID
+    app-id:
+        user-id: com.examlple.MyUserIdMechanism

Example 99.5. MyUserIdMechanism.java

public class MyUserIdMechanism implements AppIdUserIdMechanism {
+
+  @Override
+  public String createUserId() {
+    String userId = ...
+    return userId;
+  }
+}

See also: Vault Documentation: Using the App ID auth backend

99.3 AppRole authentication

AppRole is intended for machine +authentication, like the deprecated (since Vault 0.6.1) Section 99.2, “AppId authentication”. +AppRole authentication consists of two hard to guess (secret) tokens: RoleId and SecretId.

Spring Vault supports AppRole authentication by providing either RoleId only +or together with a provided SecretId (push or pull mode).

RoleId and optionally SecretId must be provided by configuration, +Spring Vault will not look up these or create a custom SecretId.

Example 99.6. bootstrap.yml with AppRole authentication properties

spring.cloud.vault:
+    authentication: APPROLE
+    app-role:
+        role-id: bde2076b-cccb-3cf0-d57e-bca7b1e83a52

  • role-id sets the RoleId.

Example 99.7. bootstrap.yml with all AppRole authentication properties

spring.cloud.vault:
+    authentication: APPROLE
+    app-role:
+        role-id: bde2076b-cccb-3cf0-d57e-bca7b1e83a52
+        secret-id: 1696536f-1976-73b1-b241-0b4213908d39
+        app-auth-path: approle

  • role-id sets the RoleId.
  • secret-id sets the SecretId. SecretId can be omitted if AppRole is configured without requiring SecretId (See bind_secret_id)
  • approle-path sets the path of the approle authentication mount to use

See also: Vault Documentation: Using the AppRole auth backend

99.4 AWS-EC2 authentication

The aws-ec2 +auth backend provides a secure introduction mechanism +for AWS EC2 instances, allowing automated retrieval of a Vault +token. Unlike most Vault authentication backends, this backend +does not require first-deploying, or provisioning security-sensitive +credentials (tokens, username/password, client certificates, etc.). +Instead, it treats AWS as a Trusted Third Party and uses the +cryptographically signed dynamic metadata information that uniquely +represents each EC2 instance.

Example 99.8. bootstrap.yml using AWS-EC2 Authentication

spring.cloud.vault:
+    authentication: AWS_EC2

AWS-EC2 authentication enables nonce by default to follow +the Trust On First Use (TOFU) principle. Any unintended party that +gains access to the PKCS#7 identity metadata can authenticate +against Vault.

During the first login, Spring Cloud Vault generates a nonce +that is stored in the auth backend aside the instance Id. +Re-authentication requires the same nonce to be sent. Any other +party does not have the nonce and can raise an alert in Vault for +further investigation.

The nonce is kept in memory and is lost during application restart. +You can configure a static nonce with spring.cloud.vault.aws-ec2.nonce.

AWS-EC2 authentication roles are optional and default to the AMI. +You can configure the authentication role by setting the +spring.cloud.vault.aws-ec2.role property.

Example 99.9. bootstrap.yml with configured role

spring.cloud.vault:
+    authentication: AWS_EC2
+    aws-ec2:
+        role: application-server

Example 99.10. bootstrap.yml with all AWS EC2 authentication properties

spring.cloud.vault:
+    authentication: AWS_EC2
+    aws-ec2:
+        role: application-server
+        aws-ec2-path: aws-ec2
+        identity-document: http://...
+        nonce: my-static-nonce

  • authentication setting this value to AWS_EC2 selects the AWS EC2 +authentication method
  • role sets the name of the role against which the login is being attempted.
  • aws-ec2-path sets the path of the AWS EC2 mount to use
  • identity-document sets URL of the PKCS#7 AWS EC2 identity document
  • nonce used for AWS-EC2 authentication. An empty nonce defaults to nonce generation

See also: Vault Documentation: Using the aws auth backend

99.5 AWS-IAM authentication

The aws backend provides a secure +authentication mechanism for AWS IAM roles, allowing the automatic authentication with +vault based on the current IAM role of the running application. + Unlike most Vault authentication backends, this backend +does not require first-deploying, or provisioning security-sensitive +credentials (tokens, username/password, client certificates, etc.). +Instead, it treats AWS as a Trusted Third Party and uses the +4 pieces of information signed by the caller with their IAM credentials + to verify that the caller is indeed using that IAM role.

The current IAM role the application is running in is automatically calculated. +If you are running your application on AWS ECS then the application +will use the IAM role assigned to the ECS task of the running container. +If you are running your application naked on top of an EC2 instance then +the IAM role used will be the one assigned to the EC2 instance.

When using the AWS-IAM authentication you must create a role in Vault +and assign it to your IAM role. An empty role defaults to +the friendly name the current IAM role.

Example 99.11. bootstrap.yml with required AWS-IAM Authentication properties

spring.cloud.vault:
+    authentication: AWS_IAM

Example 99.12. bootstrap.yml with all AWS-IAM Authentication properties

spring.cloud.vault:
+    authentication: AWS_IAM
+    aws-iam:
+        role: my-dev-role
+        aws-path: aws
+        server-id: some.server.name

  • role sets the name of the role against which the login is being attempted. This should be bound to your IAM role. If one is not supplied then the friendly name of the current IAM user will be used as the vault role.
  • aws-path sets the path of the AWS mount to use
  • server-id sets the value to use for the X-Vault-AWS-IAM-Server-ID header preventing certain types of replay attacks.

AWS-IAM requires the AWS Java SDK dependency (com.amazonaws:aws-java-sdk-core) +as the authentication implementation uses AWS SDK types for credentials and request signing.

See also: Vault Documentation: Using the aws auth backend

99.6 TLS certificate authentication

The cert auth backend allows authentication using SSL/TLS client +certificates that are either signed by a CA or self-signed.

To enable cert authentication you need to:

  1. Use SSL, see Chapter 105, Vault Client SSL configuration
  2. Configure a Java Keystore that contains the client +certificate and the private key
  3. Set the spring.cloud.vault.authentication to CERT

Example 99.13. bootstrap.yml

spring.cloud.vault:
+    authentication: CERT
+    ssl:
+        key-store: classpath:keystore.jks
+        key-store-password: changeit
+        cert-auth-path: cert

See also: Vault Documentation: Using the Cert auth backend

99.7 Cubbyhole authentication

Cubbyhole authentication uses Vault primitives to provide a secured authentication +workflow. Cubbyhole authentication uses tokens as primary login method. +An ephemeral token is used to obtain a second, login VaultToken from Vault’s +Cubbyhole secret backend. The login token is usually longer-lived and used to +interact with Vault. The login token will be retrieved from a wrapped +response stored at /cubbyhole/response.

Creating a wrapped token

[Note]Note

Response Wrapping for token creation requires Vault 0.6.0 or higher.

Example 99.14. Creating and storing tokens

$ vault token-create -wrap-ttl="10m"
+Key                            Value
+---                            -----
+wrapping_token:                397ccb93-ff6c-b17b-9389-380b01ca2645
+wrapping_token_ttl:            0h10m0s
+wrapping_token_creation_time:  2016-09-18 20:29:48.652957077 +0200 CEST
+wrapped_accessor:              46b6aebb-187f-932a-26d7-4f3d86a68319

Example 99.15. bootstrap.yml

spring.cloud.vault:
+    authentication: CUBBYHOLE
+    token: 397ccb93-ff6c-b17b-9389-380b01ca2645

See also:

99.8 Kubernetes authentication

Kubernetes authentication mechanism (since Vault 0.8.3) allows to authenticate with Vault using a Kubernetes Service Account Token. +The authentication is role based and the role is bound to a service account name and a namespace.

A file containing a JWT token for a pod’s service account is automatically mounted at /var/run/secrets/kubernetes.io/serviceaccount/token.

Example 99.16. bootstrap.yml with all Kubernetes authentication properties

spring.cloud.vault:
+    authentication: KUBERNETES
+    kubernetes:
+        role: my-dev-role
+        service-account-token-file: /var/run/secrets/kubernetes.io/serviceaccount/token

  • role sets the Role.
  • service-account-token-file sets the location of the file containing the Kubernetes Service Account Token. Defaults to /var/run/secrets/kubernetes.io/serviceaccount/token.

See also:

100. Secret Backends

100.1 Generic Backend

Spring Cloud Vault supports at the basic level the generic secret +backend. The generic secret backend allows storage of arbitrary +values as key-value store. A single context can store one or many +key-value tuples. Contexts can be organized hierarchically. +Spring Cloud Vault allows using the Application name +and a default context name (application) in combination with active +profiles.

/secret/{application}/{profile}
+/secret/{application}
+/secret/{default-context}/{profile}
+/secret/{default-context}

The application name is determined by the properties:

  • spring.cloud.vault.generic.application-name
  • spring.cloud.vault.application-name
  • spring.application.name

Secrets can be obtained from other folders within the generic backend by adding their +paths to the application name, separated by commas. For example, given the application +name usefulapp,mysql1,projectx/aws, each of these folders will be used:

  • /secret/usefulapp
  • /secret/mysql1
  • /secret/projectx/aws

Spring Cloud Vault adds all active profiles to the list of possible context paths. +No active profiles will skip accessing contexts with a profile name.

Properties are exposed like they are stored (i.e. without additional prefixes).

spring.cloud.vault:
+    generic:
+        enabled: true
+        backend: secret
+        profile-separator: '/'
+        default-context: application
+        application-name: my-app
  • enabled setting this value to false disables the secret backend +config usage
  • backend sets the path of the secret mount to use
  • default-context sets the context name used by all applications
  • application-name overrides the application name for use in the generic backend
  • profile-separator separates the profile name from the context in +property sources with profiles

See also: Vault Documentation: Using the generic secret backend

100.2 Consul

Spring Cloud Vault can obtain credentials for HashiCorp Consul. +The Consul integration requires the spring-cloud-vault-config-consul +dependency.

Example 100.1. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-consul</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

The integration can be enabled by setting +spring.cloud.vault.consul.enabled=true (default false) and +providing the role name with spring.cloud.vault.consul.role=….

The obtained token is stored in spring.cloud.consul.token +so using Spring Cloud Consul can pick up the generated +credentials without further configuration. You can configure +the property name by setting spring.cloud.vault.consul.token-property.

spring.cloud.vault:
+    consul:
+        enabled: true
+        role: readonly
+        backend: consul
+        token-property: spring.cloud.consul.token
  • enabled setting this value to true enables the Consul backend config usage
  • role sets the role name of the Consul role definition
  • backend sets the path of the Consul mount to use
  • token-property sets the property name in which the Consul ACL token is stored

See also: Vault Documentation: Setting up Consul with Vault

100.3 RabbitMQ

Spring Cloud Vault can obtain credentials for RabbitMQ.

The RabbitMQ integration requires the spring-cloud-vault-config-rabbitmq +dependency.

Example 100.2. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-rabbitmq</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

The integration can be enabled by setting +spring.cloud.vault.rabbitmq.enabled=true (default false) +and providing the role name with spring.cloud.vault.rabbitmq.role=….

Username and password are stored in spring.rabbitmq.username +and spring.rabbitmq.password so using Spring Boot will pick up the generated +credentials without further configuration. You can configure the property names +by setting spring.cloud.vault.rabbitmq.username-property and +spring.cloud.vault.rabbitmq.password-property.

spring.cloud.vault:
+    rabbitmq:
+        enabled: true
+        role: readonly
+        backend: rabbitmq
+        username-property: spring.rabbitmq.username
+        password-property: spring.rabbitmq.password
  • enabled setting this value to true enables the RabbitMQ backend config usage
  • role sets the role name of the RabbitMQ role definition
  • backend sets the path of the RabbitMQ mount to use
  • username-property sets the property name in which the RabbitMQ username is stored
  • password-property sets the property name in which the RabbitMQ password is stored

See also: Vault Documentation: Setting up RabbitMQ with Vault

100.4 AWS

Spring Cloud Vault can obtain credentials for AWS.

The AWS integration requires the spring-cloud-vault-config-aws +dependency.

Example 100.3. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-aws</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

The integration can be enabled by setting +spring.cloud.vault.aws=true (default false) +and providing the role name with spring.cloud.vault.aws.role=….

The access key and secret key are stored in cloud.aws.credentials.accessKey +and cloud.aws.credentials.secretKey so using Spring Cloud AWS will pick up the generated +credentials without further configuration. You can configure the property names +by setting spring.cloud.vault.aws.access-key-property and +spring.cloud.vault.aws.secret-key-property.

spring.cloud.vault:
+    aws:
+        enabled: true
+        role: readonly
+        backend: aws
+        access-key-property: cloud.aws.credentials.accessKey
+        secret-key-property: cloud.aws.credentials.secretKey
  • enabled setting this value to true enables the AWS backend config usage
  • role sets the role name of the AWS role definition
  • backend sets the path of the AWS mount to use
  • access-key-property sets the property name in which the AWS access key is stored
  • secret-key-property sets the property name in which the AWS secret key is stored

See also: Vault Documentation: Setting up AWS with Vault

101. Database backends

Vault supports several database secret backends to generate database +credentials dynamically based on configured roles. This means +services that need to access a database no longer need to configure +credentials: they can request them from Vault, and use Vault’s leasing +mechanism to more easily roll keys.

Spring Cloud Vault integrates with these backends:

Using a database secret backend requires to enable the +backend in the configuration and the spring-cloud-vault-config-databases +dependency.

Vault ships since 0.7.1 with a dedicated database secret backend that allows +database integration via plugins. You can use that specific backend by adapting +one of the JDBC database properties above. Make sure to specify the appropriate +backend path, e.g. spring.cloud.vault.mysql.role.backend=database.

Example 101.1. pom.xml

<dependencies>
+    <dependency>
+        <groupId>org.springframework.cloud</groupId>
+        <artifactId>spring-cloud-vault-config-databases</artifactId>
+        <version>1.3.8.RELEASE</version>
+    </dependency>
+</dependencies>

[Note]Note

Enabling multiple JDBC-compliant databases will generate credentials +and store them by default in the same property keys hence property names for +JDBC secrets need to be configured separately.

101.1 Apache Cassandra

Spring Cloud Vault can obtain credentials for Apache Cassandra. +The integration can be enabled by setting +spring.cloud.vault.cassandra.enabled=true (default false) and +providing the role name with spring.cloud.vault.cassandra.role=….

Username and password are stored in spring.data.cassandra.username +and spring.data.cassandra.password so using Spring Boot will pick +up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.cassandra.username-property and +spring.cloud.vault.cassandra.password-property.

spring.cloud.vault:
+    cassandra:
+        enabled: true
+        role: readonly
+        backend: cassandra
+        username-property: spring.data.cassandra.username
+        password-property: spring.data.cassandra.username
  • enabled setting this value to true enables the Cassandra backend config usage
  • role sets the role name of the Cassandra role definition
  • backend sets the path of the Cassandra mount to use
  • username-property sets the property name in which the Cassandra username is stored
  • password-property sets the property name in which the Cassandra password is stored

See also: Vault Documentation: Setting up Apache Cassandra with Vault

101.2 MongoDB

Spring Cloud Vault can obtain credentials for MongoDB. +The integration can be enabled by setting +spring.cloud.vault.mongodb.enabled=true (default false) and +providing the role name with spring.cloud.vault.mongodb.role=….

Username and password are stored in spring.data.mongodb.username +and spring.data.mongodb.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.mongodb.username-property and +spring.cloud.vault.mongodb.password-property.

spring.cloud.vault:
+    mongodb:
+        enabled: true
+        role: readonly
+        backend: mongodb
+        username-property: spring.data.mongodb.username
+        password-property: spring.data.mongodb.password
  • enabled setting this value to true enables the MongodB backend config usage
  • role sets the role name of the MongoDB role definition
  • backend sets the path of the MongoDB mount to use
  • username-property sets the property name in which the MongoDB username is stored
  • password-property sets the property name in which the MongoDB password is stored

See also: Vault Documentation: Setting up MongoDB with Vault

101.3 MySQL

Spring Cloud Vault can obtain credentials for MySQL. +The integration can be enabled by setting +spring.cloud.vault.mysql.enabled=true (default false) and +providing the role name with spring.cloud.vault.mysql.role=….

Username and password are stored in spring.datasource.username +and spring.datasource.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.mysql.username-property and +spring.cloud.vault.mysql.password-property.

spring.cloud.vault:
+    mysql:
+        enabled: true
+        role: readonly
+        backend: mysql
+        username-property: spring.datasource.username
+        password-property: spring.datasource.username
  • enabled setting this value to true enables the MySQL backend config usage
  • role sets the role name of the MySQL role definition
  • backend sets the path of the MySQL mount to use
  • username-property sets the property name in which the MySQL username is stored
  • password-property sets the property name in which the MySQL password is stored

See also: Vault Documentation: Setting up MySQL with Vault

101.4 PostgreSQL

Spring Cloud Vault can obtain credentials for PostgreSQL. +The integration can be enabled by setting +spring.cloud.vault.postgresql.enabled=true (default false) and +providing the role name with spring.cloud.vault.postgresql.role=….

Username and password are stored in spring.datasource.username +and spring.datasource.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.postgresql.username-property and +spring.cloud.vault.postgresql.password-property.

spring.cloud.vault:
+    postgresql:
+        enabled: true
+        role: readonly
+        backend: postgresql
+        username-property: spring.datasource.username
+        password-property: spring.datasource.username
  • enabled setting this value to true enables the PostgreSQL backend config usage
  • role sets the role name of the PostgreSQL role definition
  • backend sets the path of the PostgreSQL mount to use
  • username-property sets the property name in which the PostgreSQL username is stored
  • password-property sets the property name in which the PostgreSQL password is stored

See also: Vault Documentation: Setting up PostgreSQL with Vault

102. Configure PropertySourceLocator behavior

Spring Cloud Vault uses property-based configuration to create PropertySources +for generic and discovered secret backends.

Discovered backends provide VaultSecretBackendDescriptor beans to describe the configuration +state to use secret backend as PropertySource. A SecretBackendMetadataFactory is required +to create a SecretBackendMetadata object which contains path, name and property transformation +configuration.

SecretBackendMetadata is used to back a particular PropertySource.

You can register an arbitrary number of beans implementing VaultConfigurer for customization. +Default generic and discovered backend registration is disabled if Spring Cloud Vault discovers +at least one VaultConfigurer bean. You can however enable default registration with +SecretBackendConfigurer.registerDefaultGenericSecretBackends() and SecretBackendConfigurer.registerDefaultDiscoveredSecretBackends().

public class CustomizationBean implements VaultConfigurer {
+
+    @Override
+    public void addSecretBackends(SecretBackendConfigurer configurer) {
+
+        configurer.add("secret/my-application");
+
+        configurer.registerDefaultGenericSecretBackends(false);
+        configurer.registerDefaultDiscoveredSecretBackends(true);
+    }
+}
[Note]Note

All customization is required to happen in the bootstrap context. Add your configuration +classes to META-INF/spring.factories at org.springframework.cloud.bootstrap.BootstrapConfiguration +in your application.

103. Service Registry Configuration

You can use a DiscoveryClient (such as from Spring Cloud Consul) to locate +a Vault server by setting spring.cloud.vault.discovery.enabled=true (default false). +The net result of that is that your apps need a bootstrap.yml (or an environment variable) +with the appropriate discovery configuration. +The benefit is that the Vault can change its co-ordinates, as long as the discovery service +is a fixed point. The default service id is vault but you can change that on the client with +spring.cloud.vault.discovery.serviceId.

The discovery client implementations all support some kind of metadata map +(e.g. for Eureka we have eureka.instance.metadataMap). Some additional properties of the service +may need to be configured in its service registration metadata so that clients can connect +correctly. Service registries that do not provide details about transport layer security +need to provide a scheme metadata entry to be set either to https or http. +If no scheme is configured and the service is not exposed as secure service, then +configuration defaults to spring.cloud.vault.scheme which is https when it’s not set.

spring.cloud.vault.discovery:
+    enabled: true
+    service-id: my-vault-service

104. Vault Client Fail Fast

In some cases, it may be desirable to fail startup of a service if +it cannot connect to the Vault Server. If this is the desired +behavior, set the bootstrap configuration property +spring.cloud.vault.fail-fast=true and the client will halt with +an Exception.

spring.cloud.vault:
+    fail-fast: true

105. Vault Client SSL configuration

SSL can be configured declaratively by setting various properties. +You can set either javax.net.ssl.trustStore to configure +JVM-wide SSL settings or spring.cloud.vault.ssl.trust-store +to set SSL settings only for Spring Cloud Vault Config.

spring.cloud.vault:
+    ssl:
+        trust-store: classpath:keystore.jks
+        trust-store-password: changeit
  • trust-store sets the resource for the trust-store. SSL-secured Vault +communication will validate the Vault SSL certificate with the specified +trust-store.
  • trust-store-password sets the trust-store password

Please note that configuring spring.cloud.vault.ssl.* can be only +applied when either Apache Http Components or the OkHttp client +is on your class-path.

106. Lease lifecycle management (renewal and revocation)

With every secret, Vault creates a lease: +metadata containing information such as a time duration, +renewability, and more.

Vault promises that the data will be valid for the given duration, +or Time To Live (TTL). Once the lease is expired, Vault can +revoke the data, and the consumer of the secret can no longer +be certain that it is valid.

Spring Cloud Vault maintains a lease lifecycle beyond +the creation of login tokens and secrets. That said, +login tokens and secrets associated with a lease +are scheduled for renewal just before the lease expires +until terminal expiry. +Application shutdown revokes obtained login tokens and renewable +leases.

Secret service and database backends (such as MongoDB or MySQL) +usually generate a renewable lease so generated credentials will +be disabled on application shutdown.

[Note]Note

Static tokens are not renewed or revoked.

Lease renewal and revocation is enabled by default and can +be disabled by setting spring.cloud.vault.config.lifecycle.enabled +to false. This is not recommended as leases can expire and +Spring Cloud Vault cannot longer access Vault or services +using generated credentials and valid credentials remain active +after application shutdown.

spring.cloud.vault:
+    config.lifecycle.enabled: true

See also: Vault Documentation: Lease, Renew, and Revoke

Part XV. Spring Cloud Function

Mark Fisher, Dave Syer

107. Introduction

Spring Cloud Function is a project with the following high-level goals:

  • Promote the implementation of business logic via functions.
  • Decouple the development lifecycle of business logic from any specific runtime target so that the same code can run as a web endpoint, a stream processor, or a task.
  • Support a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS).
  • Enable Spring Boot features (auto-configuration, dependency injection, metrics) on serverless providers.

It abstracts away all of the transport details and +infrastructure, allowing the developer to keep all the familiar tools +and processes, and focus firmly on business logic.

Here’s a complete, executable, testable Spring Boot application +(implementing a simple string manipulation):

@SpringBootApplication
+public class Application {
+
+  @Bean
+  public Function<Flux<String>, Flux<String>> uppercase() {
+    return flux -> flux.map(value -> value.toUpperCase());
+  }
+
+  public static void main(String[] args) {
+    SpringApplication.run(Application.class, args);
+  }
+}

It’s just a Spring Boot application, so it can be built, run and +tested, locally and in a CI build, the same way as any other Spring +Boot application. The Function is from java.util and Flux is a +Reactive Streams Publisher from +Project Reactor. The function can be +accessed over HTTP or messaging.

Spring Cloud Function has 4 main features:

  1. Wrappers for @Beans of type Function, Consumer and +Supplier, exposing them to the outside world as either HTTP +endpoints and/or message stream listeners/publishers with RabbitMQ, Kafka etc.
  2. Compiling strings which are Java function bodies into bytecode, and +then turning them into @Beans that can be wrapped as above.
  3. Deploying a JAR file containing such an application context with an +isolated classloader, so that you can pack them together in a single +JVM.
  4. Adapters for AWS Lambda, Azure, Apache OpenWhisk and possibly other "serverless" service providers.
[Note]Note

Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github.

108. Getting Started

Build from the command line (and "install" the samples):

$ ./mvnw clean install

(If you like to YOLO add -DskipTests.)

Run one of the samples, e.g.

$ java -jar spring-cloud-function-samples/function-sample/target/*.jar

This runs the app and exposes its functions over HTTP, so you can +convert a string to uppercase, like this:

$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d Hello
+HELLO

You can convert multiple strings (a Flux<String>) by separating them +with new lines

$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d 'Hello
+> World'
+HELLOWORLD

(You can use QJ in a terminal to insert a new line in a literal +string like that.)

109. Building and Running a Function

The sample @SpringBootApplication above has a function that can be +decorated at runtime by Spring Cloud Function to be an HTTP endpoint, +or a Stream processor, for instance with RabbitMQ, Apache Kafka or +JMS.

The @Beans can be Function, Consumer or Supplier (all from +java.util), and their parametric types can be String or POJO. A +Function is exposed as a Spring Cloud Stream Processor if +spring-cloud-function-stream is on the classpath. +A Consumer is also exposed as a Stream +Sink and a Supplier translates to a Stream Source. +HTTP endpoints are exposed if the Stream binder is spring-cloud-stream-binder-servlet.

Functions can be of Flux<String> or Flux<Pojo> and Spring Cloud +Function takes care of converting the data to and from the desired +types, as long as it comes in as plain text or (in the case of the +POJO) JSON. TBD: support for Flux<Message<Pojo>> and maybe plain +Pojo types (Fluxes implied and implemented by the framework).

Functions can be grouped together in a single application, or deployed +one-per-jar. It’s up to the developer to choose. An app with multiple +functions can be deployed multiple times in different "personalities", +exposing different functions over different physical transports.

110. Function Catalog and Flexible Function Signatures

One of the main features of Spring Cloud Function is to adapt and +support a range of type signatures for user-defined functions. So +users can supply a bean of type Function<String,String>, for +instance, and the FunctionCatalog will wrap it into a +Function<Flux<String>,Flux<String>>. Users don’t normally have to +care about the FunctionCatalog at all, but it is useful to know what +kind of functions are supported in user code.

Generally speaking users can expect that if they write a function for +a plain old Java type (or primitive wrapper), then the function +catalog will wrap it to a Flux of the same type. If the user writes +a function using Message (from spring-messaging) it will receive and +transmit headers from any adapter that supports key-value metadata +(e.g. HTTP headers). Here are the details.

User FunctionCatalog Registration 

Function<S,T>

Function<Flux<S>, Flux<T>>

 

Function<Message<S>,Message<T>>

Function<Flux<Message<S>>, Flux<Message<T>>>

 

Function<Flux<S>, Flux<T>>

Function<Flux<S>, Flux<T>> (pass through)

 

Supplier<T>

Supplier<Flux<T>>

 

Supplier<Flux<T>>

Supplier<Flux<T>>

 

Consumer<T>

Function<Flux<T>, Mono<Void>>

 

Consumer<Message<T>>

Function<Flux<Message<T>>, Mono<Void>>

 

Consumer<Flux<T>>

Consumer<Flux<T>>

 

Consumer is a little bit special because it has a void return type, +which implies blocking, at least potentially. Most likely you will not +need to write Consumer<Flux<?>>, but if you do need to do that, +remember to subscribe to the input flux. If you declare a Consumer +of a non publisher type (which is normal), it will be converted to a +function that returns a publisher, so that it can be subscribed to in +a controlled way.

A function catalog can contain a Supplier and a Function (or +Consumer) with the same name (like a GET and a POST to the same +resource). It can even contain a Consumer<Flux<>> with the same name +as a Function, but it cannot contain a Consumer<T> and a +Function<T,S> with the same name when T is not a Publisher +because the consumer would be converted to a Function and only one +of them can be registered.

111. Standalone Web Applications

The spring-cloud-function-web module has autoconfiguration that +activates when it is included in a Spring Boot web application (with +MVC support). There is also a spring-cloud-starter-function-web to +collect all the optional dependnecies in case you just want a simple +getting started experience.

With the web configurations activated your app will have an MVC +endpoint (on "/" by default, but configurable with +spring.cloud.function.web.path) that can be used to access the +functions in the application context. The supported content types are +plain text and JSON.

MethodPathRequestResponseStatus

GET

/{supplier}

-

Items from the named supplier

200 OK

POST

/{consumer}

JSON object or text

Mirrors input and pushes request body into consumer

202 Accepted

POST

/{consumer}

JSON array or text with new lines

Mirrors input and pushes body into consumer one by one

202 Accepted

POST

/{function}

JSON object or text

The result of applying the named function

200 OK

POST

/{function}

JSON array or text with new lines

The result of applying the named function

200 OK

GET

/{function}/{item}

-

Convert the item into an object and return the result of applying the function

200 OK

As the table above shows the behaviour of the endpoint depends on the method and also the type of incoming request data. When the incoming data is single valued, and the target function is declared as obviously single valued (i.e. not returning a collection or Flux), then the response will also contain a single value. For multi-valued responses the client can ask for a server-sent event stream by sending `Accept: text/event-stream". If there is only one function (consumer etc.) then the name in the path is optional. Composite functions can be addressed using pipes or commas to separate function names (pipes are legal in URL paths, but a bit awkward to type on the command line).

Functions and consumers that are declared with input and output in Message<?> will see the request headers on the input messages, and the output message headers will be converted to HTTP headers.

When POSTing text the response format might be different with Spring Boot 2.0 and older versions, depending on the content negotiation (provide content type and accpt headers for the best results).

112. Standalone Streaming Applications

To send or receive messages from a broker (such as RabbitMQ or Kafka) you can use the spring-cloud-function-stream adapter. Add the adapter to your classpath along with the appropriate binder from Spring Cloud Stream. The adapter will bind to the message broker as a Processor (input and output streams) unless the user explicitly disables one or the other using spring.cloud.function.stream.{source,sink}.enabled=false.

An incoming message is routed to a function (or consumer). If there is only one, then the choice is obvious. If there are multiple functions that can accept an incoming message, the message is inspected to see if there is a stream_routekey header containing the name of a function. Routing headers or function names can be composed using a comma- or pipe-separated name. The header is also added to outgoing messages from a supplier. Messages with no route key can be routed exclusively to a function or consumer by specifying spring.cloud.function.stream.{processor,sink}.name. If a single function cannot be identified to process an incoming message there will be an error, unless you set spring.cloud.function.stream.shared=true, in which case such messages will be sent to all compatible functions. A single supplier can be chosen for output messages from a supplier (if more than one is available) using the spring.cloud.function.stream.source.name.

[Note]Note

some binders will fail on startup if the message broker is not available and the function catalog contains suppliers that immediately produce messages when accessed. You can switch off the automatic publishing from suppliers on startup using the spring.cloud.function.strean.supplier.enabled=false flag.

113. Deploying a Packaged Function

Spring Cloud Function provides a "deployer" library that allows you to launch a jar file (or exploded archive, or set of jar files) with an isolated class loader and expose the functions defined in it. This is quite a powerful tool that would allow you to, for instance, adapt a function to a range of different input-output adapters without changing the target jar file. Serverless platforms often have this kind of feature built in, so you could see it as a building block for a function invoker in such a platform (indeed the Riff Java function invoker uses this library).

The standard entry point of the API is the Spring configuration annotation @EnableFunctionDeployer. If that is used in a Spring Boot application the deployer kicks in and looks for some configuration to tell it where to find the function jar. At a minimum the user has to provide a function.location which is a URL or resource location for the archive containing the functions. It can optionally use a maven: prefix to locate the artifact via a dependency lookup (see FunctionProperties for complete details). A Spring Boot application is bootstrapped from the jar file, using the MANIFEST.MF to locate a start class, so that a standard Spring Boot fat jar works well, for example. If the target jar can be launched successfully then the result is a function registered in the main application’s FunctionCatalog. The registered function can be applied by code in the main application, even though it was created in an isolated class loader (by deault).

114. Dynamic Compilation

There is a sample app that uses the function compiler to create a +function from a configuration property. The vanilla "function-sample" +also has that feature. And there are some scripts that you can run to +see the compilation happening at run time. To run these examples, +change into the scripts directory:

cd scripts

Also, start a RabbitMQ server locally (e.g. execute rabbitmq-server).

Start the Function Registry Service:

./function-registry.sh

Register a Function:

./registerFunction.sh -n uppercase -f "f->f.map(s->s.toString().toUpperCase())"

Run a REST Microservice using that Function:

./web.sh -f uppercase -p 9000
+curl -H "Content-Type: text/plain" -H "Accept: text/plain" localhost:9000/uppercase -d foo

Register a Supplier:

./registerSupplier.sh -n words -f "()->Flux.just(\"foo\",\"bar\")"

Run a REST Microservice using that Supplier:

./web.sh -s words -p 9001
+curl -H "Accept: application/json" localhost:9001/words

Register a Consumer:

./registerConsumer.sh -n print -t String -f "System.out::println"

Run a REST Microservice using that Consumer:

./web.sh -c print -p 9002
+curl -X POST -H "Content-Type: text/plain" -d foo localhost:9002/print

Run Stream Processing Microservices:

First register a streaming words supplier:

./registerSupplier.sh -n wordstream -f "()->Flux.interval(Duration.ofMillis(1000)).map(i->\"message-\"+i)"

Then start the source (supplier), processor (function), and sink (consumer) apps +(in reverse order):

./stream.sh -p 9103 -i uppercaseWords -c print
+./stream.sh -p 9102 -i words -f uppercase -o uppercaseWords
+./stream.sh -p 9101 -s wordstream -o words

The output will appear in the console of the sink app (one message per second, converted to uppercase):

MESSAGE-0
+MESSAGE-1
+MESSAGE-2
+MESSAGE-3
+MESSAGE-4
+MESSAGE-5
+MESSAGE-6
+MESSAGE-7
+MESSAGE-8
+MESSAGE-9
+...

115. Serverless Platform Adapters

As well as being able to run as a standalone process, a Spring Cloud +Function application can be adapted to run one of the existing +serverless platforms. In the project there are adapters for +AWS +Lambda, +Azure, +and +Apache +OpenWhisk. The Oracle Fn platform +has its own Spring Cloud Function adapter. And +Riff supports Java functions and its +Java Function +Invoker acts natively is an adapter for Spring Cloud Function jars.

115.1 AWS Lambda

The AWS adapter takes a Spring Cloud Function app and converts it to a form that can run in AWS Lambda.

115.1.1 Introduction

The adapter has a couple of generic request handlers that you can use. The most generic is SpringBootStreamHandler, which uses a Jackson ObjectMapper provided by Spring Boot to serialize and deserialize the objects in the function. There is also a SpringBootRequestHandler which you can extend, and provide the input and output types as type parameters (enabling AWS to inspect the class and do the JSON conversions itself).

If your app has more than one @Bean of type Function etc. then you can choose the one to use by configuring function.name (e.g. as FUNCTION_NAME environment variable in AWS). The functions are extracted from the Spring Cloud FunctionCatalog (searching first for Function then Consumer and finally Supplier).

115.1.2 Notes on JAR Layout

You don’t need the Spring Cloud Function Web or Stream adapter at runtime in Lambda, so you might need to exclude those before you create the JAR you send to AWS. A Lambda application has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample). The sample app creates 2 jar files, one with an aws classifier for deploying in Lambda, and one executable (thin) jar that includes spring-cloud-function-web at runtime. Spring Cloud Function will try and locate a "main class" for you from the JAR file manifest, using the Start-Class attribute (which will be added for you by the Spring Boot tooling if you use the starter parent). If there is no Start-Class in your manifest you can use an environment variable MAIN_CLASS when you deploy the function to AWS.

115.1.3 Upload

Build the sample under spring-cloud-function-samples/function-sample-aws and upload the -aws jar file to Lambda. The handler can be example.Handler or org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler (FQN of the class, not a method reference, although Lambda does accept method references).

./mvnw -U clean package

Using the AWS command line tools it looks like this:

aws lambda create-function --function-name Uppercase --role arn:aws:iam::[USERID]:role/service-role/[ROLE] --zip-file fileb://function-sample-aws/target/function-sample-aws-1.0.2.RELEASE-aws.jar --handler org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler --description "Spring Cloud Function Adapter Example" --runtime java8 --region us-east-1 --timeout 30 --memory-size 1024 --publish

The input type for the function in the AWS sample is a Foo with a single property called "value". So you would need this to test it:

{
+  "value": "test"
+}

115.1.4 Platfom Specific Features

HTTP and API Gateway

AWS has some platform-specific data types, including batching of messages, which is much more efficient than processing each one individually. To make use of these types you can write a function that depends on those types. Or you can rely on Spring to extract the data from the AWS types and convert it to a Spring Message. To do this you tell AWS that the function is of a specific generic handler type (depending on the AWS service) and provide a bean of type Function<Message<S>,Message<T>>, where S and T are your business data types. If there is more than one bean of type Function you may also need to configure the Spring Boot property function.name to be the name of the target bean (e.g. use FUNCTION_NAME as an environment variable).

The supported AWS services and generic handler types are listed below:

ServiceAWS TypesGeneric Handler 

API Gateway

APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent

org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler

 

Kinesis

KinesisEvent

org.springframework.cloud.function.adapter.aws.SpringBootKinesisEventHandler

 

For example, to deploy behind an API Gateway, use --handler org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler in your AWS command line (in via the UI) and define a @Bean of type Function<Message<Foo>,Message<Bar>> where Foo and Bar are POJO types (the data will be marshalled and unmarshalled by AWS using Jackson).

115.2 Azure Functions

The Azure adapter bootstraps a Spring Cloud Function context and channels function calls from the Azure framework into the user functions, using Spring Boot configuration where necessary. Azure Functions has quite a unique, but invasive programming model, involving annotations in user code that are specific to the platform. The Spring Cloud Function Azure adapter trades the convenience of these annotations for portability of the function implementations. Instead of using the annotations you have to write some JSON by hand (at least for now) to guide the platform to call the right methods in the adapter.

This project provides an adapter layer for a Spring Cloud Function application onto Azure. +You can write an app with a single @Bean of type Function and it will be deployable in Azure if you get the JAR file laid out right.

The adapter has a generic HTTP request handler that you can use optionally. +There is a AzureSpringBootRequestHandler which you must extend, and provide the input and output types as type parameters (enabling Azure to inspect the class and do the JSON conversions itself).

If your app has more than one @Bean of type Function etc. then you can choose the one to use by configuring function.name. +The functions are extracted from the Spring Cloud FunctionCatalog.

115.2.1 Notes on JAR Layout

You don’t need the Spring Cloud Function Web at runtime in Azure, so you need to exclude this before you create the JAR you deploy to Azure. +A function application on Azure has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample here). +The sample app creates the shaded jar file, with an azure classifier for deploying in Azure.

115.2.2 JSON Configuration

The Azure tooling needs to find some JSON configuration files to tell it how to deploy and integrate the function (e.g. which Java class to use as the entry point, and which triggers to use). Those files can be created with the Maven plugin for a non-Spring function, but the tooling doesn’t work yet with the adapter in its current form. There is an example function.json in the sample which hooks the function up as an HTTP endpoint:

{
+  "scriptFile" : "../function-sample-azure-1.0.2.RELEASE-azure.jar",
+  "entryPoint" : "example.FooHandler.execute",
+  "bindings" : [ {
+    "type" : "httpTrigger",
+    "name" : "foo",
+    "direction" : "in",
+    "authLevel" : "anonymous",
+    "methods" : [ "get", "post" ]
+  }, {
+    "type" : "http",
+    "name" : "$return",
+    "direction" : "out"
+  } ],
+  "disabled" : false
+}

115.2.3 Build

./mvnw -U clean package

115.2.4 Running the sample

You can run the sample locally, just like the other Spring Cloud Function samples:

and curl -H "Content-Type: text/plain" localhost:8080/function -d '{"value": "hello foobar"}'.

You will need the az CLI app and some node.js fu (see https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven for more detail). To deploy the function on Azure runtime:

$ az login
+$ mvn azure-functions:deploy

On another terminal try this: curl https://<azure-function-url-from-the-log>/api/uppercase -d '{"value": "hello foobar!"}'. Please ensure that you use the right URL for the function above. Alternatively you can test the function in the Azure Dashboard UI (click on the function name, go to the right hand side and click "Test" and to the bottom right, "Run").

The input type for the function in the Azure sample is a Foo with a single property called "value". So you need this to test it with something like below:

{
+  "value": "foobar"
+}

115.3 Apache Openwhisk

The OpenWhisk adapter is in the form of an executable jar that can be used in a a docker image to be deployed to Openwhisk. The platform works in request-response mode, listening on port 8080 on a specific endpoint, so the adapter is a simple Spring MVC application.

115.3.1 Quick Start

Implement a POF (be sure to use the functions package):

package functions;
+
+import java.util.function.Function;
+
+public class Uppercase implements Function<String, String> {
+
+	public String apply(String input) {
+		return input.toUpperCase();
+	}
+}

Install it into your local Maven repository:

./mvnw clean install

Create a function.properties file that provides its Maven coordinates. For example:

dependencies.function: com.example:pof:0.0.1-SNAPSHOT

Copy the openwhisk runner JAR to the working directory (same directory as the properties file):

cp spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk/target/spring-cloud-function-adapter-openwhisk-1.0.2.RELEASE.jar runner.jar

Generate a m2 repo from the --thin.dryrun of the runner JAR with the above properties file:

java -jar -Dthin.root=m2 runner.jar --thin.name=function --thin.dryrun

Use the following Dockerfile:

FROM openjdk:8-jdk-alpine
+VOLUME /tmp
+COPY m2 /m2
+ADD runner.jar .
+ADD function.properties .
+ENV JAVA_OPTS=""
+ENTRYPOINT [ "java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "runner.jar", "--thin.root=/m2", "--thin.name=function", "--function.name=uppercase"]
+EXPOSE 8080
[Note]Note

you could use a Spring Cloud Function app, instead of just a jar with a POF in it, in which case you would have to change the way the app runs in the container so that it picks up the main class as a source file. For example, you could change the ENTRYPOINT above and add --spring.main.sources=com.example.SampleApplication.

Build the Docker image:

docker build -t [username/appname] .

Push the Docker image:

docker push [username/appname]

Use the OpenWhisk CLI (e.g. after vagrant ssh) to create the action:

wsk action create example --docker [username/appname]

Invoke the action:

wsk action invoke example --result --param payload foo
+{
+    "result": "FOO"
+}

Part XVI. Appendix: Compendium of Configuration Properties

NameDefaultDescription

archaius.propagate.environmentChangedEvent

true

Propagates EnvironmentChanged events to Archaius ConfigurationManager.

encrypt.fail-on-error

true

Flag to say that a process should fail if there is an encryption or decryption error.

encrypt.key

 

A symmetric key. As a stronger alternative consider using a keystore.

encrypt.key-store.alias

 

Alias for a key in the store.

encrypt.key-store.location

 

Location of the key store file, e.g. classpath:/keystore.jks.

encrypt.key-store.password

 

Password that locks the keystore.

encrypt.key-store.secret

 

Secret protecting the key (defaults to the same as the password).

encrypt.rsa.algorithm

 

The RSA algorithm to use (DEFAULT or OEAP). Once it is set do not change it (or existing ciphers will not a decryptable).

encrypt.rsa.salt

deadbeef

Salt for the random secret used to encrypt cipher text. Once it is set do not change it (or existing ciphers will not a decryptable).

encrypt.rsa.strong

false

Flag to indicate that "strong" AES encryption should be used internally. If true then the GCM algorithm is applied to the AES encrypted bytes. Default is false (in which case "standard" CBC is used instead). Once it is set do not change it (or existing ciphers will not a decryptable).

endpoints.bus.enabled

  

endpoints.bus.id

  

endpoints.bus.sensitive

  

endpoints.consul.enabled

  

endpoints.consul.id

  

endpoints.consul.sensitive

  

endpoints.env.post.enabled

true

Enable changing the Environment through a POST to /env.

endpoints.features.enabled

  

endpoints.features.id

  

endpoints.features.sensitive

  

endpoints.pause.enabled

true

Enable the /pause endpoint (to send Lifecycle.stop()).

endpoints.pause.id

  

endpoints.pause.sensitive

  

endpoints.refresh.enabled

true

Enable the /refresh endpoint to refresh configuration and re-initialize refresh scoped beans.

endpoints.refresh.id

  

endpoints.refresh.sensitive

  

endpoints.restart.enabled

true

Enable the /restart endpoint to restart the application context.

endpoints.restart.id

  

endpoints.restart.pause-endpoint.enabled

  

endpoints.restart.pause-endpoint.id

  

endpoints.restart.pause-endpoint.sensitive

  

endpoints.restart.resume-endpoint.enabled

  

endpoints.restart.resume-endpoint.id

  

endpoints.restart.resume-endpoint.sensitive

  

endpoints.restart.sensitive

  

endpoints.restart.timeout

0

 

endpoints.resume.enabled

true

Enable the /resume endpoint (to send Lifecycle.start()).

endpoints.resume.id

  

endpoints.resume.sensitive

  

endpoints.routes.enabled

  

endpoints.routes.id

  

endpoints.routes.sensitive

  

endpoints.zookeeper.enabled

true

Enable the /zookeeper endpoint to inspect the state of zookeeper.

eureka.client.allow-redirects

false

Indicates whether server can redirect a client request to a backup server/cluster. If set to false, the server will handle the request directly, If set to true, it may send HTTP redirect to the client, with a new server location.

eureka.client.availability-zones

 

Gets the list of availability zones (used in AWS data centers) for the region in which this instance resides. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds.

eureka.client.backup-registry-impl

 

Gets the name of the implementation which implements BackupRegistry to fetch the registry information as a fall back option for only the first time when the eureka client starts. This may be needed for applications which needs additional resiliency for registry information without which it cannot operate.

eureka.client.cache-refresh-executor-exponential-back-off-bound

10

Cache refresh executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred.

eureka.client.cache-refresh-executor-thread-pool-size

2

The thread pool size for the cacheRefreshExecutor to initialise with

eureka.client.client-data-accept

 

EurekaAccept name for client data accept

eureka.client.decoder-name

 

This is a transient config and once the latest codecs are stable, can be removed (as there will only be one)

eureka.client.disable-delta

false

Indicates whether the eureka client should disable fetching of delta and should rather resort to getting the full registry information. Note that the delta fetches can reduce the traffic tremendously, because the rate of change with the eureka server is normally much lower than the rate of fetches. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds

eureka.client.dollar-replacement

_-

Get a replacement string for Dollar sign <code>$</code> during serializing/deserializing information in eureka server.

eureka.client.enabled

true

Flag to indicate that the Eureka client is enabled.

eureka.client.encoder-name

 

This is a transient config and once the latest codecs are stable, can be removed (as there will only be one)

eureka.client.escape-char-replacement

__

Get a replacement string for underscore sign <code>_</code> during serializing/deserializing information in eureka server.

eureka.client.eureka-connection-idle-timeout-seconds

30

Indicates how much time (in seconds) that the HTTP connections to eureka server can stay idle before it can be closed. In the AWS environment, it is recommended that the values is 30 seconds or less, since the firewall cleans up the connection information after a few mins leaving the connection hanging in limbo

eureka.client.eureka-server-connect-timeout-seconds

5

Indicates how long to wait (in seconds) before a connection to eureka server needs to timeout. Note that the connections in the client are pooled by org.apache.http.client.HttpClient and this setting affects the actual connection creation and also the wait time to get the connection from the pool.

eureka.client.eureka-server-d-n-s-name

 

Gets the DNS name to be queried to get the list of eureka servers.This information is not required if the contract returns the service urls by implementing serviceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.

eureka.client.eureka-server-port

 

Gets the port to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS.This information is not required if the contract returns the service urls eurekaServerServiceUrls(String). The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.

eureka.client.eureka-server-read-timeout-seconds

8

Indicates how long to wait (in seconds) before a read from eureka server needs to timeout.

eureka.client.eureka-server-total-connections

200

Gets the total number of connections that is allowed from eureka client to all eureka servers.

eureka.client.eureka-server-total-connections-per-host

50

Gets the total number of connections that is allowed from eureka client to a eureka server host.

eureka.client.eureka-server-u-r-l-context

 

Gets the URL context to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS. This information is not required if the contract returns the service urls from eurekaServerServiceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.

eureka.client.eureka-service-url-poll-interval-seconds

0

Indicates how often(in seconds) to poll for changes to eureka server information. Eureka servers could be added or removed and this setting controls how soon the eureka clients should know about it.

eureka.client.fetch-registry

true

Indicates whether this client should fetch eureka registry information from eureka server.

eureka.client.fetch-remote-regions-registry

 

Comma separated list of regions for which the eureka registry information will be fetched. It is mandatory to define the availability zones for each of these regions as returned by availabilityZones. Failing to do so, will result in failure of discovery client startup.

eureka.client.filter-only-up-instances

true

Indicates whether to get the applications after filtering the applications for instances with only InstanceStatus UP states.

eureka.client.g-zip-content

true

Indicates whether the content fetched from eureka server has to be compressed whenever it is supported by the server. The registry information from the eureka server is compressed for optimum network traffic.

eureka.client.healthcheck.enabled

true

Enables the Eureka health check handler.

eureka.client.heartbeat-executor-exponential-back-off-bound

10

Heartbeat executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred.

eureka.client.heartbeat-executor-thread-pool-size

2

The thread pool size for the heartbeatExecutor to initialise with

eureka.client.initial-instance-info-replication-interval-seconds

40

Indicates how long initially (in seconds) to replicate instance info to the eureka server

eureka.client.instance-info-replication-interval-seconds

30

Indicates how often(in seconds) to replicate instance changes to be replicated to the eureka server.

eureka.client.log-delta-diff

false

Indicates whether to log differences between the eureka server and the eureka client in terms of registry information. Eureka client tries to retrieve only delta changes from eureka server to minimize network traffic. After receiving the deltas, eureka client reconciles the information from the server to verify it has not missed out some information. Reconciliation failures could happen when the client has had network issues communicating to server.If the reconciliation fails, eureka client gets the full registry information. While getting the full registry information, the eureka client can log the differences between the client and the server and this setting controls that. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSecondsr

eureka.client.on-demand-update-status-change

true

If set to true, local status updates via ApplicationInfoManager will trigger on-demand (but rate limited) register/updates to remote eureka servers

eureka.client.prefer-same-zone-eureka

true

Indicates whether or not this instance should try to use the eureka server in the same zone for latency and/or other reason. Ideally eureka clients are configured to talk to servers in the same zone The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds

eureka.client.property-resolver

  

eureka.client.proxy-host

 

Gets the proxy host to eureka server if any.

eureka.client.proxy-password

 

Gets the proxy password if any.

eureka.client.proxy-port

 

Gets the proxy port to eureka server if any.

eureka.client.proxy-user-name

 

Gets the proxy user name if any.

eureka.client.region

us-east-1

Gets the region (used in AWS datacenters) where this instance resides.

eureka.client.register-with-eureka

true

Indicates whether or not this instance should register its information with eureka server for discovery by others. In some cases, you do not want your instances to be discovered whereas you just want do discover other instances.

eureka.client.registry-fetch-interval-seconds

30

Indicates how often(in seconds) to fetch the registry information from the eureka server.

eureka.client.registry-refresh-single-vip-address

 

Indicates whether the client is only interested in the registry information for a single VIP.

eureka.client.service-url

 

Map of availability zone to list of fully qualified URLs to communicate with eureka server. Each value can be a single URL or a comma separated list of alternative locations. Typically the eureka server URLs carry protocol,host,port,context and version information if any. Example: https://ec2-256-156-243-129.compute-1.amazonaws.com:7001/eureka/ The changes are effective at runtime at the next service url refresh cycle as specified by eurekaServiceUrlPollIntervalSeconds.

eureka.client.use-dns-for-fetching-service-urls

false

Indicates whether the eureka client should use the DNS mechanism to fetch a list of eureka servers to talk to. When the DNS name is updated to have additional servers, that information is used immediately after the eureka client polls for that information as specified in eurekaServiceUrlPollIntervalSeconds. Alternatively, the service urls can be returned serviceUrls, but the users should implement their own mechanism to return the updated list in case of changes. The changes are effective at runtime.

eureka.dashboard.enabled

true

Flag to enable the Eureka dashboard. Default true.

eureka.dashboard.path

/

The path to the Eureka dashboard (relative to the servlet path). Defaults to "/".

eureka.instance.a-s-g-name

 

Gets the AWS autoscaling group name associated with this instance. This information is specifically used in an AWS environment to automatically put an instance out of service after the instance is launched and it has been disabled for traffic..

eureka.instance.app-group-name

 

Get the name of the application group to be registered with eureka.

eureka.instance.appname

unknown

Get the name of the application to be registered with eureka.

eureka.instance.data-center-info

 

Returns the data center this instance is deployed. This information is used to get some AWS specific instance information if the instance is deployed in AWS.

eureka.instance.default-address-resolution-order

[]

 

eureka.instance.environment

  

eureka.instance.health-check-url

 

Gets the absolute health check page URL for this instance. The users can provide the healthCheckUrlPath if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime.

eureka.instance.health-check-url-path

/health

Gets the relative health check URL path for this instance. The health check page URL is then constructed out of the hostname and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage.

eureka.instance.home-page-url

 

Gets the absolute home page URL for this instance. The users can provide the homePageUrlPath if the home page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to use it as a landing page. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime.

eureka.instance.home-page-url-path

/

Gets the relative home page URL Path for this instance. The home page URL is then constructed out of the hostName and the type of communication - secure or unsecure. It is normally used for informational purposes for other services to use it as a landing page.

eureka.instance.hostname

 

The hostname if it can be determined at configuration time (otherwise it will be guessed from OS primitives).

eureka.instance.initial-status

 

Initial status to register with rmeote Eureka server.

eureka.instance.instance-enabled-onit

false

Indicates whether the instance should be enabled for taking traffic as soon as it is registered with eureka. Sometimes the application might need to do some pre-processing before it is ready to take traffic.

eureka.instance.instance-id

 

Get the unique Id (within the scope of the appName) of this instance to be registered with eureka.

eureka.instance.ip-address

 

Get the IPAdress of the instance. This information is for academic purposes only as the communication from other instances primarily happen using the information supplied in {@link #getHostName(boolean)}.

eureka.instance.lease-expiration-duration-in-seconds

90

Indicates the time in seconds that the eureka server waits since it received the last heartbeat before it can remove this instance from its view and there by disallowing traffic to this instance. Setting this value too long could mean that the traffic could be routed to the instance even though the instance is not alive. Setting this value too small could mean, the instance may be taken out of traffic because of temporary network glitches.This value to be set to atleast higher than the value specified in leaseRenewalIntervalInSeconds.

eureka.instance.lease-renewal-interval-in-seconds

30

Indicates how often (in seconds) the eureka client needs to send heartbeats to eureka server to indicate that it is still alive. If the heartbeats are not received for the period specified in leaseExpirationDurationInSeconds, eureka server will remove the instance from its view, there by disallowing traffic to this instance. Note that the instance could still not take traffic if it implements HealthCheckCallback and then decides to make itself unavailable.

eureka.instance.metadata-map

 

Gets the metadata name/value pairs associated with this instance. This information is sent to eureka server and can be used by other instances.

eureka.instance.namespace

eureka

Get the namespace used to find properties. Ignored in Spring Cloud.

eureka.instance.non-secure-port

80

Get the non-secure port on which the instance should receive traffic.

eureka.instance.non-secure-port-enabled

true

Indicates whether the non-secure port should be enabled for traffic or not.

eureka.instance.prefer-ip-address

false

Flag to say that, when guessing a hostname, the IP address of the server should be used in prference to the hostname reported by the OS.

eureka.instance.registry.default-open-for-traffic-count

1

Value used in determining when leases are cancelled, default to 1 for standalone. Should be set to 0 for peer replicated eurekas

eureka.instance.registry.expected-number-of-renews-per-min

1

 

eureka.instance.secure-health-check-url

 

Gets the absolute secure health check page URL for this instance. The users can provide the secureHealthCheckUrl if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime.

eureka.instance.secure-port

443

Get the Secure port on which the instance should receive traffic.

eureka.instance.secure-port-enabled

false

Indicates whether the secure port should be enabled for traffic or not.

eureka.instance.secure-virtual-host-name

unknown

Gets the secure virtual host name defined for this instance. This is typically the way other instance would find this instance by using the secure virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance.

eureka.instance.status-page-url

 

Gets the absolute status page URL path for this instance. The users can provide the statusPageUrlPath if the status page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance.

eureka.instance.status-page-url-path

/info

Gets the relative status page URL path for this instance. The status page URL is then constructed out of the hostName and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance.

eureka.instance.virtual-host-name

unknown

Gets the virtual host name defined for this instance. This is typically the way other instance would find this instance by using the virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance.

eureka.server.a-s-g-cache-expiry-timeout-ms

0

 

eureka.server.a-s-g-query-timeout-ms

300

 

eureka.server.a-s-g-update-interval-ms

0

 

eureka.server.a-w-s-access-id

  

eureka.server.a-w-s-secret-key

  

eureka.server.batch-replication

false

 

eureka.server.binding-strategy

  

eureka.server.delta-retention-timer-interval-in-ms

0

 

eureka.server.disable-delta

false

 

eureka.server.disable-delta-for-remote-regions

false

 

eureka.server.disable-transparent-fallback-to-other-region

false

 

eureka.server.e-i-p-bind-rebind-retries

3

 

eureka.server.e-i-p-binding-retry-interval-ms

0

 

eureka.server.e-i-p-binding-retry-interval-ms-when-unbound

0

 

eureka.server.enable-replicated-request-compression

false

 

eureka.server.enable-self-preservation

true

 

eureka.server.eviction-interval-timer-in-ms

0

 

eureka.server.g-zip-content-from-remote-region

true

 

eureka.server.json-codec-name

  

eureka.server.list-auto-scaling-groups-role-name

ListAutoScalingGroups

 

eureka.server.log-identity-headers

true

 

eureka.server.max-elements-in-peer-replication-pool

10000

 

eureka.server.max-elements-in-status-replication-pool

10000

 

eureka.server.max-idle-thread-age-in-minutes-for-peer-replication

15

 

eureka.server.max-idle-thread-in-minutes-age-for-status-replication

10

 

eureka.server.max-threads-for-peer-replication

20

 

eureka.server.max-threads-for-status-replication

1

 

eureka.server.max-time-for-replication

30000

 

eureka.server.min-available-instances-for-peer-replication

-1

 

eureka.server.min-threads-for-peer-replication

5

 

eureka.server.min-threads-for-status-replication

1

 

eureka.server.number-of-replication-retries

5

 

eureka.server.peer-eureka-nodes-update-interval-ms

0

 

eureka.server.peer-eureka-status-refresh-time-interval-ms

0

 

eureka.server.peer-node-connect-timeout-ms

200

 

eureka.server.peer-node-connection-idle-timeout-seconds

30

 

eureka.server.peer-node-read-timeout-ms

200

 

eureka.server.peer-node-total-connections

1000

 

eureka.server.peer-node-total-connections-per-host

500

 

eureka.server.prime-aws-replica-connections

true

 

eureka.server.property-resolver

  

eureka.server.rate-limiter-burst-size

10

 

eureka.server.rate-limiter-enabled

false

 

eureka.server.rate-limiter-full-fetch-average-rate

100

 

eureka.server.rate-limiter-privileged-clients

  

eureka.server.rate-limiter-registry-fetch-average-rate

500

 

eureka.server.rate-limiter-throttle-standard-clients

false

 

eureka.server.registry-sync-retries

0

 

eureka.server.registry-sync-retry-wait-ms

0

 

eureka.server.remote-region-app-whitelist

  

eureka.server.remote-region-connect-timeout-ms

1000

 

eureka.server.remote-region-connection-idle-timeout-seconds

30

 

eureka.server.remote-region-fetch-thread-pool-size

20

 

eureka.server.remote-region-read-timeout-ms

1000

 

eureka.server.remote-region-registry-fetch-interval

30

 

eureka.server.remote-region-total-connections

1000

 

eureka.server.remote-region-total-connections-per-host

500

 

eureka.server.remote-region-trust-store

  

eureka.server.remote-region-trust-store-password

changeit

 

eureka.server.remote-region-urls

  

eureka.server.remote-region-urls-with-name

  

eureka.server.renewal-percent-threshold

0.85

 

eureka.server.renewal-threshold-update-interval-ms

0

 

eureka.server.response-cache-auto-expiration-in-seconds

180

 

eureka.server.response-cache-update-interval-ms

0

 

eureka.server.retention-time-in-m-s-in-delta-queue

0

 

eureka.server.route53-bind-rebind-retries

3

 

eureka.server.route53-binding-retry-interval-ms

0

 

eureka.server.route53-domain-t-t-l

30

 

eureka.server.sync-when-timestamp-differs

true

 

eureka.server.use-read-only-response-cache

true

 

eureka.server.wait-time-in-ms-when-sync-empty

0

 

eureka.server.xml-codec-name

  

feign.client.config

  

feign.client.default-config

default

 

feign.client.default-to-properties

true

 

feign.compression.request.mime-types

[text/xml, application/xml, application/json]

The list of supported mime types.

feign.compression.request.min-request-size

2048

The minimum threshold content size.

feign.httpclient.connection-timeout

2000

 

feign.httpclient.connection-timer-repeat

3000

 

feign.httpclient.disable-ssl-validation

false

 

feign.httpclient.follow-redirects

true

 

feign.httpclient.max-connections

200

 

feign.httpclient.max-connections-per-route

50

 

feign.httpclient.time-to-live

900

 

feign.httpclient.time-to-live-unit

  

health.config.enabled

false

Flag to indicate that the config server health indicator should be installed.

health.config.time-to-live

0

Time to live for cached result, in milliseconds. Default 300000 (5 min).

hystrix.metrics.enabled

true

Enable Hystrix metrics polling. Defaults to true.

hystrix.metrics.polling-interval-ms

2000

Interval between subsequent polling of metrics. Defaults to 2000 ms.

hystrix.shareSecurityContext

false

Enables auto-configuration of the Hystrix concurrency strategy plugin hook who will transfer the SecurityContext from your main thread to the one used by the Hystrix command.

management.health.refresh.enabled

true

Enable the health endpoint for the refresh scope.

management.health.zookeeper.enabled

true

Enable the health endpoint for zookeeper.

management.metrics.binders.hystrix.enabled

true

Enables creation of OK Http Client factory beans.

netflix.atlas.batch-size

10000

 

netflix.atlas.enabled

true

 

netflix.atlas.uri

  

netflix.metrics.servo.cache-warning-threshold

1000

When the ServoMonitorCache reaches this size, a warning is logged. This will be useful if you are using string concatenation in RestTemplate urls.

netflix.metrics.servo.registry-class

com.netflix.servo.BasicMonitorRegistry

Fully qualified class name for monitor registry used by Servo.

proxy.auth.load-balanced

false

 

proxy.auth.routes

 

Authentication strategy per route.

ribbon.eager-load.clients

  

ribbon.eager-load.enabled

false

 

ribbon.eureka.enabled

true

Enables the use of Eureka with Ribbon.

ribbon.http.client.enabled

false

Deprecated property to enable Ribbon RestClient.

ribbon.okhttp.enabled

false

Enables the use of the OK HTTP Client with Ribbon.

ribbon.restclient.enabled

false

Enables the use of the deprecated Ribbon RestClient.

ribbon.secure-ports

  

spring.cloud.bus.ack.destination-service

 

Service that wants to listen to acks. By default null (meaning all services).

spring.cloud.bus.ack.enabled

true

Flag to switch off acks (default on).

spring.cloud.bus.destination

springCloudBus

Name of Spring Cloud Stream destination for messages.

spring.cloud.bus.enabled

true

Flag to indicate that the bus is enabled.

spring.cloud.bus.env.enabled

true

Flag to switch off environment change events (default on).

spring.cloud.bus.refresh.enabled

true

Flag to switch off refresh events (default on).

spring.cloud.bus.trace.enabled

false

Flag to switch on tracing of acks (default off).

spring.cloud.cloudfoundry.discovery.enabled

true

Flag to indicate that discovery is enabled.

spring.cloud.cloudfoundry.discovery.heartbeat-frequency

5000

Frequency in milliseconds of poll for heart beat. The client will poll on this frequency and broadcast a list of service ids.

spring.cloud.cloudfoundry.discovery.org

 

Organization name to authenticate with (default to user’s default).

spring.cloud.cloudfoundry.discovery.password

 

Password for user to authenticate and obtain token.

spring.cloud.cloudfoundry.discovery.space

 

Space name to authenticate with (default to user’s default).

spring.cloud.cloudfoundry.discovery.url

https://api.run.pivotal.io

URL of Cloud Foundry API (Cloud Controller).

spring.cloud.cloudfoundry.discovery.username

 

Username to authenticate (usually an email address).

spring.cloud.compatibility-verifier.compatible-boot-versions

1.5.x

Default accepted versions for the Spring Boot dependency. You can set {@code x} for the patch version if you don’t want to specify a concrete value. Example: {@code 3.4.x}

spring.cloud.compatibility-verifier.enabled

false

Enables creation of Spring Cloud compatibility verification.

spring.cloud.config.allow-override

true

Flag to indicate that {@link #isOverrideSystemProperties() systemPropertiesOverride} can be used. Set to false to prevent users from changing the default accidentally. Default true.

spring.cloud.config.authorization

 

Authorization token used by the client to connect to the server.

spring.cloud.config.discovery.enabled

false

Flag to indicate that config server discovery is enabled (config server URL will be looked up via discovery).

spring.cloud.config.discovery.service-id

configserver

Service id to locate config server.

spring.cloud.config.enabled

true

Flag to say that remote configuration is enabled. Default true;

spring.cloud.config.fail-fast

false

Flag to indicate that failure to connect to the server is fatal (default false).

spring.cloud.config.headers

 

Additional headers used to create the client request.

spring.cloud.config.label

 

The label name to use to pull remote configuration properties. The default is set on the server (generally "master" for a git based server).

spring.cloud.config.name

 

Name of application used to fetch remote properties.

spring.cloud.config.override-none

false

Flag to indicate that when {@link #setAllowOverride(boolean) allowOverride} is true, external properties should take lowest priority, and not override any existing property sources (including local config files). Default false.

spring.cloud.config.override-system-properties

true

Flag to indicate that the external properties should override system properties. Default true.

spring.cloud.config.password

 

The password to use (HTTP Basic) when contacting the remote server.

spring.cloud.config.profile

default

The default profile to use when fetching remote configuration (comma-separated). Default is "default".

spring.cloud.config.retry.initial-interval

1000

Initial retry interval in milliseconds.

spring.cloud.config.retry.max-attempts

6

Maximum number of attempts.

spring.cloud.config.retry.max-interval

2000

Maximum interval for backoff.

spring.cloud.config.retry.multiplier

1.1

Multiplier for next interval.

spring.cloud.config.server.bootstrap

false

Flag indicating that the config server should initialize its own Environment with properties from the remote repository. Off by default because it delays startup but can be useful when embedding the server in another application.

spring.cloud.config.server.default-application-name

application

Default application name when incoming requests do not have a specific one.

spring.cloud.config.server.default-label

 

Default repository label when incoming requests do not have a specific label.

spring.cloud.config.server.default-profile

default

Default application profile when incoming requests do not have a specific one.

spring.cloud.config.server.encrypt.enabled

true

Enable decryption of environment properties before sending to client.

spring.cloud.config.server.git.basedir

 

Base directory for local working copy of repository.

spring.cloud.config.server.git.clone-on-start

false

Flag to indicate that the repository should be cloned on startup (not on demand). Generally leads to slower startup but faster first query.

spring.cloud.config.server.git.default-label

master

 

spring.cloud.config.server.git.delete-untracked-branches

false

Flag to indicate that the branch should be deleted locally if it’s origin tracked branch was removed.

spring.cloud.config.server.git.environment

  

spring.cloud.config.server.git.force-pull

false

Flag to indicate that the repository should force pull. If true discard any local changes and take from remote repository.

spring.cloud.config.server.git.git-credentials-provider

 

The credentials provider to use to connect to the Git repository.

spring.cloud.config.server.git.git-factory

  

spring.cloud.config.server.git.host-key

  

spring.cloud.config.server.git.host-key-algorithm

  

spring.cloud.config.server.git.ignore-local-ssh-settings

false

 

spring.cloud.config.server.git.known-hosts-file

  

spring.cloud.config.server.git.last-refresh

0

Time of the last refresh of the git repository

spring.cloud.config.server.git.order

  

spring.cloud.config.server.git.passphrase

 

Passphrase for unlocking your ssh private key.

spring.cloud.config.server.git.password

 

Password for authentication with remote repository.

spring.cloud.config.server.git.preferred-authentications

  

spring.cloud.config.server.git.private-key

  

spring.cloud.config.server.git.proxy-host

  

spring.cloud.config.server.git.proxy-port

  

spring.cloud.config.server.git.refresh-rate

0

Time (in seconds) between refresh of the git repository

spring.cloud.config.server.git.repos

 

Map of repository identifier to location and other properties.

spring.cloud.config.server.git.search-paths

 

Search paths to use within local working copy. By default searches only the root.

spring.cloud.config.server.git.strict-host-key-checking

true

Reject incoming SSH host keys from remote servers not in the known host list.

spring.cloud.config.server.git.timeout

5

Timeout (in seconds) for obtaining HTTP or SSH connection (if applicable). Default 5 seconds.

spring.cloud.config.server.git.transport-config-callback

 

Transport configuration callback for JGit commands.

spring.cloud.config.server.git.uri

 

URI of remote repository.

spring.cloud.config.server.git.username

 

Username for authentication with remote repository.

spring.cloud.config.server.health.repositories

  

spring.cloud.config.server.jdbc.order

0

 

spring.cloud.config.server.jdbc.sql

SELECT KEY, VALUE from PROPERTIES where APPLICATION=? and PROFILE=? and LABEL=?

 

spring.cloud.config.server.native.add-label-locations

true

Flag to determine whether label locations should be added.

spring.cloud.config.server.native.default-label

master

 

spring.cloud.config.server.native.fail-on-error

false

Flag to determine how to handle exceptions during decryption (default false).

spring.cloud.config.server.native.order

  

spring.cloud.config.server.native.search-locations

[]

Locations to search for configuration files. Defaults to the same as a Spring Boot app so [classpath:/,classpath:/config/,file:./,file:./config/].

spring.cloud.config.server.native.version

 

Version string to be reported for native repository

spring.cloud.config.server.overrides

 

Extra map for a property source to be sent to all clients unconditionally.

spring.cloud.config.server.prefix

 

Prefix for configuration resource paths (default is empty). Useful when embedding in another application when you don’t want to change the context path or servlet path.

spring.cloud.config.server.strip-document-from-yaml

true

Flag to indicate that YAML documents that are text or collections (not a map) should be returned in "native" form.

spring.cloud.config.server.svn.basedir

 

Base directory for local working copy of repository.

spring.cloud.config.server.svn.default-label

trunk

The default label for environment properties requests.

spring.cloud.config.server.svn.environment

  

spring.cloud.config.server.svn.order

  

spring.cloud.config.server.svn.passphrase

 

Passphrase for unlocking your ssh private key.

spring.cloud.config.server.svn.password

 

Password for authentication with remote repository.

spring.cloud.config.server.svn.search-paths

 

Search paths to use within local working copy. By default searches only the root.

spring.cloud.config.server.svn.strict-host-key-checking

true

Reject incoming SSH host keys from remote servers not in the known host list.

spring.cloud.config.server.svn.uri

 

URI of remote repository.

spring.cloud.config.server.svn.username

 

Username for authentication with remote repository.

spring.cloud.config.server.vault.order

  

spring.cloud.config.token

 

Security Token passed thru to underlying environment repository.

spring.cloud.config.uri

http://localhost:8888

The URI of the remote server (default http://localhost:8888).

spring.cloud.config.username

 

The username to use (HTTP Basic) when contacting the remote server.

spring.cloud.consul.config.acl-token

  

spring.cloud.consul.config.data-key

data

If format is Format.PROPERTIES or Format.YAML then the following field is used as key to look up consul for configuration.

spring.cloud.consul.config.default-context

application

 

spring.cloud.consul.config.enabled

true

 

spring.cloud.consul.config.fail-fast

true

Throw exceptions during config lookup if true, otherwise, log warnings.

spring.cloud.consul.config.format

  

spring.cloud.consul.config.name

 

Alternative to spring.application.name to use in looking up values in consul KV.

spring.cloud.consul.config.prefix

config

 

spring.cloud.consul.config.profile-separator

,

 

spring.cloud.consul.config.watch.delay

1000

The value of the fixed delay for the watch in millis. Defaults to 1000.

spring.cloud.consul.config.watch.enabled

true

If the watch is enabled. Defaults to true.

spring.cloud.consul.config.watch.wait-time

55

The number of seconds to wait (or block) for watch query, defaults to 55. Needs to be less than default ConsulClient (defaults to 60). To increase ConsulClient timeout create a ConsulClient bean with a custom ConsulRawClient with a custom HttpClient.

spring.cloud.consul.discovery.acl-token

  

spring.cloud.consul.discovery.catalog-services-watch-delay

10

 

spring.cloud.consul.discovery.catalog-services-watch-timeout

2

 

spring.cloud.consul.discovery.datacenters

 

Map of serviceId’s → datacenter to query for in server list. This allows looking up services in another datacenters.

spring.cloud.consul.discovery.default-query-tag

 

Tag to query for in service list if one is not listed in serverListQueryTags.

spring.cloud.consul.discovery.default-zone-metadata-name

zone

Service instance zone comes from metadata. This allows changing the metadata tag name.

spring.cloud.consul.discovery.deregister

true

Disable automatic de-registration of service in consul.

spring.cloud.consul.discovery.enabled

true

Is service discovery enabled?

spring.cloud.consul.discovery.fail-fast

true

Throw exceptions during service registration if true, otherwise, log warnings (defaults to true).

spring.cloud.consul.discovery.health-check-critical-timeout

 

Timeout to deregister services critical for longer than timeout (e.g. 30m). Requires consul version 7.x or higher.

spring.cloud.consul.discovery.health-check-interval

10s

How often to perform the health check (e.g. 10s), defaults to 10s.

spring.cloud.consul.discovery.health-check-path

/health

Alternate server path to invoke for health checking

spring.cloud.consul.discovery.health-check-timeout

 

Timeout for health check (e.g. 10s).

spring.cloud.consul.discovery.health-check-tls-skip-verify

 

Skips certificate verification during service checks if true, otherwise runs certificate verification.

spring.cloud.consul.discovery.health-check-url

 

Custom health check url to override default

spring.cloud.consul.discovery.heartbeat.enabled

false

 

spring.cloud.consul.discovery.heartbeat.heartbeat-interval

  

spring.cloud.consul.discovery.heartbeat.interval-ratio

  

spring.cloud.consul.discovery.heartbeat.ttl-unit

s

 

spring.cloud.consul.discovery.heartbeat.ttl-value

30

 

spring.cloud.consul.discovery.hostname

 

Hostname to use when accessing server

spring.cloud.consul.discovery.instance-group

 

Service instance group

spring.cloud.consul.discovery.instance-id

 

Unique service instance id

spring.cloud.consul.discovery.instance-zone

 

Service instance zone

spring.cloud.consul.discovery.ip-address

 

IP address to use when accessing service (must also set preferIpAddress to use)

spring.cloud.consul.discovery.lifecycle.enabled

true

 

spring.cloud.consul.discovery.management-port

 

Port to register the management service under (defaults to management port)

spring.cloud.consul.discovery.management-suffix

management

Suffix to use when registering management service

spring.cloud.consul.discovery.management-tags

 

Tags to use when registering management service

spring.cloud.consul.discovery.port

 

Port to register the service under (defaults to listening port)

spring.cloud.consul.discovery.prefer-agent-address

false

Source of how we will determine the address to use

spring.cloud.consul.discovery.prefer-ip-address

false

Use ip address rather than hostname during registration

spring.cloud.consul.discovery.query-passing

false

Add the 'passing` parameter to /v1/health/service/serviceName. This pushes health check passing to the server.

spring.cloud.consul.discovery.register

true

Register as a service in consul.

spring.cloud.consul.discovery.register-health-check

true

Register health check in consul. Useful during development of a service.

spring.cloud.consul.discovery.scheme

http

Whether to register an http or https service

spring.cloud.consul.discovery.server-list-query-tags

 

Map of serviceId’s → tag to query for in server list. This allows filtering services by a single tag.

spring.cloud.consul.discovery.service-name

 

Service name

spring.cloud.consul.discovery.tags

 

Tags to use when registering service

spring.cloud.consul.enabled

true

Is spring cloud consul enabled

spring.cloud.consul.host

localhost

Consul agent hostname. Defaults to 'localhost'.

spring.cloud.consul.port

8500

Consul agent port. Defaults to '8500'.

spring.cloud.consul.retry.initial-interval

1000

Initial retry interval in milliseconds.

spring.cloud.consul.retry.max-attempts

6

Maximum number of attempts.

spring.cloud.consul.retry.max-interval

2000

Maximum interval for backoff.

spring.cloud.consul.retry.multiplier

1.1

Multiplier for next interval.

spring.cloud.consul.tls.certificate-password

 

Password to open the certificate.

spring.cloud.consul.tls.certificate-path

 

File path to the certificate.

spring.cloud.consul.tls.key-store-instance-type

 

Type of key framework to use.

spring.cloud.consul.tls.key-store-password

 

Password to an external keystore

spring.cloud.consul.tls.key-store-path

 

Path to an external keystore

spring.cloud.discovery.client.composite-indicator.enabled

true

Enables discovery client composite health indicator.

spring.cloud.discovery.client.health-indicator.enabled

true

 

spring.cloud.discovery.client.health-indicator.include-description

true

 

spring.cloud.discovery.client.simple.instances

  

spring.cloud.discovery.client.simple.local.metadata

 

Metadata for the service instance. Can be used by discovery clients to modify their behaviour per instance, e.g. when load balancing.

spring.cloud.discovery.client.simple.local.service-id

 

The identifier or name for the service. Multiple instances might share the same service id.

spring.cloud.discovery.client.simple.local.uri

 

The URI of the service instance. Will be parsed to extract the scheme, hos and port.

spring.cloud.discovery.enabled

true

Enables discovery client health indicators.

spring.cloud.features.enabled

true

Enables the features endpoint.

spring.cloud.gateway.proxy.headers

 

Fixed header values that will be added to all downstream requests.

spring.cloud.gateway.proxy.sensitive

 

A set of sensitive header names that will not be sent downstream by default.

spring.cloud.httpclientfactories.apache.enabled

true

Enables creation of Apache Http Client factory beans.

spring.cloud.httpclientfactories.ok.enabled

true

Enables creation of OK Http Client factory beans.

spring.cloud.hypermedia.refresh.fixed-delay

5000

 

spring.cloud.hypermedia.refresh.initial-delay

10000

 

spring.cloud.inetutils.default-hostname

localhost

The default hostname. Used in case of errors.

spring.cloud.inetutils.default-ip-address

127.0.0.1

The default ipaddress. Used in case of errors.

spring.cloud.inetutils.ignored-interfaces

 

List of Java regex expressions for network interfaces that will be ignored.

spring.cloud.inetutils.preferred-networks

 

List of Java regex expressions for network addresses that will be preferred.

spring.cloud.inetutils.timeout-seconds

1

Timeout in seconds for calculating hostname.

spring.cloud.inetutils.use-only-site-local-interfaces

false

Use only interfaces with site local addresses. See {@link InetAddress#isSiteLocalAddress()} for more details.

spring.cloud.loadbalancer.retry.enabled

true

 

spring.cloud.refresh.enabled

true

Enables autoconfiguration for the refresh scope and associated features.

spring.cloud.service-registry.auto-registration.enabled

true

If Auto-Service Registration is enabled, default to true.

spring.cloud.service-registry.auto-registration.fail-fast

false

Should startup fail if there is no AutoServiceRegistration, default to false.

spring.cloud.service-registry.auto-registration.register-management

true

Whether to register the management as a service, defaults to true

spring.cloud.stream.binders

  

spring.cloud.stream.bindings

  

spring.cloud.stream.consul.binder.event-timeout

5

 

spring.cloud.stream.default-binder

  

spring.cloud.stream.dynamic-destinations

[]

 

spring.cloud.stream.instance-count

1

 

spring.cloud.stream.instance-index

0

 

spring.cloud.stream.integration.message-handler-not-propagated-headers

 

Message header names that will NOT be copied from the inbound message.

spring.cloud.util.enabled

true

Enables creation of Spring Cloud utility beans.

spring.cloud.vault.app-id.app-id-path

app-id

Mount path of the AppId authentication backend.

spring.cloud.vault.app-id.network-interface

 

Network interface hint for the "MAC_ADDRESS" UserId mechanism.

spring.cloud.vault.app-id.user-id

MAC_ADDRESS

UserId mechanism. Can be either "MAC_ADDRESS", "IP_ADDRESS", a string or a class name.

spring.cloud.vault.app-role.app-role-path

approle

Mount path of the AppId authentication backend.

spring.cloud.vault.app-role.role-id

 

The RoleId.

spring.cloud.vault.app-role.secret-id

 

The SecretId.

spring.cloud.vault.application-name

application

Application name for AppId authentication.

spring.cloud.vault.authentication

  

spring.cloud.vault.aws-ec2.aws-ec2-path

aws-ec2

Mount path of the AWS-EC2 authentication backend.

spring.cloud.vault.aws-ec2.identity-document

http://169.254.169.254/latest/dynamic/instance-identity/pkcs7

URL of the AWS-EC2 PKCS7 identity document.

spring.cloud.vault.aws-ec2.nonce

 

Nonce used for AWS-EC2 authentication. An empty nonce defaults to nonce generation.

spring.cloud.vault.aws-ec2.role

 

Name of the role, optional.

spring.cloud.vault.aws-ec2.use-nonce

true

Flag whether to generate and send a nonce. @deprecated not used, will be removed in a future version.

spring.cloud.vault.aws-iam.aws-path

aws

Mount path of the AWS authentication backend.

spring.cloud.vault.aws-iam.role

 

Name of the role, optional. Defaults to the friendly IAM name if not set.

spring.cloud.vault.aws-iam.server-name

 

Name of the server used to set {@code X-Vault-AWS-IAM-Server-ID} header in the headers of login requests.

spring.cloud.vault.aws.access-key-property

cloud.aws.credentials.accessKey

Target property for the obtained access key.

spring.cloud.vault.aws.backend

aws

aws backend path.

spring.cloud.vault.aws.enabled

false

Enable aws backend usage.

spring.cloud.vault.aws.role

 

Role name for credentials.

spring.cloud.vault.aws.secret-key-property

cloud.aws.credentials.secretKey

Target property for the obtained secret key.

spring.cloud.vault.cassandra.backend

cassandra

Cassandra backend path.

spring.cloud.vault.cassandra.enabled

false

Enable cassandra backend usage.

spring.cloud.vault.cassandra.password-property

spring.data.cassandra.password

Target property for the obtained password.

spring.cloud.vault.cassandra.role

 

Role name for credentials.

spring.cloud.vault.cassandra.username-property

spring.data.cassandra.username

Target property for the obtained username.

spring.cloud.vault.config.lifecycle

  

spring.cloud.vault.config.order

0

Used to set a {@link org.springframework.core.env.PropertySource} priority. This is useful to use Vault as an override on other property sources. @see org.springframework.core.PriorityOrdered

spring.cloud.vault.connection-timeout

5000

Connection timeout;

spring.cloud.vault.consul.backend

consul

Consul backend path.

spring.cloud.vault.consul.enabled

false

Enable consul backend usage.

spring.cloud.vault.consul.role

 

Role name for credentials.

spring.cloud.vault.consul.token-property

spring.cloud.consul.token

Target property for the obtained token.

spring.cloud.vault.discovery.enabled

false

Flag to indicate that Vault server discovery is enabled (vault server URL will be looked up via discovery).

spring.cloud.vault.discovery.service-id

vault

Service id to locate Vault.

spring.cloud.vault.enabled

true

Enable Vault config server.

spring.cloud.vault.fail-fast

false

Fail fast if data cannot be obtained from Vault.

spring.cloud.vault.generic.application-name

application

Application name to be used for the context.

spring.cloud.vault.generic.backend

secret

Name of the default backend.

spring.cloud.vault.generic.default-context

application

Name of the default context.

spring.cloud.vault.generic.enabled

true

Enable the generic backend.

spring.cloud.vault.generic.profile-separator

/

Profile-separator to combine application name and profile.

spring.cloud.vault.host

localhost

Vault server host.

spring.cloud.vault.kubernetes.kubernetes-path

kubernetes

Mount path of the Kubernetes authentication backend.

spring.cloud.vault.kubernetes.role

 

Name of the role against which the login is being attempted.

spring.cloud.vault.kubernetes.service-account-token-file

/var/run/secrets/kubernetes.io/serviceaccount/token

Path to the service account token file.

spring.cloud.vault.mongodb.backend

mongodb

Cassandra backend path.

spring.cloud.vault.mongodb.enabled

false

Enable mongodb backend usage.

spring.cloud.vault.mongodb.password-property

spring.data.mongodb.password

Target property for the obtained password.

spring.cloud.vault.mongodb.role

 

Role name for credentials.

spring.cloud.vault.mongodb.username-property

spring.data.mongodb.username

Target property for the obtained username.

spring.cloud.vault.mysql.backend

mysql

mysql backend path.

spring.cloud.vault.mysql.enabled

false

Enable mysql backend usage.

spring.cloud.vault.mysql.password-property

spring.datasource.password

Target property for the obtained username.

spring.cloud.vault.mysql.role

 

Role name for credentials.

spring.cloud.vault.mysql.username-property

spring.datasource.username

Target property for the obtained username.

spring.cloud.vault.port

8200

Vault server port.

spring.cloud.vault.postgresql.backend

postgresql

postgresql backend path.

spring.cloud.vault.postgresql.enabled

false

Enable postgresql backend usage.

spring.cloud.vault.postgresql.password-property

spring.datasource.password

Target property for the obtained username.

spring.cloud.vault.postgresql.role

 

Role name for credentials.

spring.cloud.vault.postgresql.username-property

spring.datasource.username

Target property for the obtained username.

spring.cloud.vault.rabbitmq.backend

rabbitmq

rabbitmq backend path.

spring.cloud.vault.rabbitmq.enabled

false

Enable rabbitmq backend usage.

spring.cloud.vault.rabbitmq.password-property

spring.rabbitmq.password

Target property for the obtained password.

spring.cloud.vault.rabbitmq.role

 

Role name for credentials.

spring.cloud.vault.rabbitmq.username-property

spring.rabbitmq.username

Target property for the obtained username.

spring.cloud.vault.read-timeout

15000

Read timeout;

spring.cloud.vault.scheme

https

Protocol scheme. Can be either "http" or "https".

spring.cloud.vault.ssl.cert-auth-path

cert

Mount path of the TLS cert authentication backend.

spring.cloud.vault.ssl.key-store

 

Trust store that holds certificates and private keys.

spring.cloud.vault.ssl.key-store-password

 

Password used to access the key store.

spring.cloud.vault.ssl.trust-store

 

Trust store that holds SSL certificates.

spring.cloud.vault.ssl.trust-store-password

 

Password used to access the trust store.

spring.cloud.vault.token

 

Static vault token. Required if {@link #authentication} is {@code TOKEN}.

spring.cloud.vault.uri

 

Vault URI. Can be set with scheme, host and port.

spring.cloud.zookeeper.base-sleep-time-ms

50

Initial amount of time to wait between retries

spring.cloud.zookeeper.block-until-connected-unit

 

The unit of time related to blocking on connection to Zookeeper

spring.cloud.zookeeper.block-until-connected-wait

10

Wait time to block on connection to Zookeeper

spring.cloud.zookeeper.connect-string

localhost:2181

Connection string to the Zookeeper cluster

spring.cloud.zookeeper.default-health-endpoint

 

Default health endpoint that will be checked to verify that a dependency is alive

spring.cloud.zookeeper.dependencies

 

Mapping of alias to ZookeeperDependency. From Ribbon perspective the alias is actually serviceID since Ribbon can’t accept nested structures in serviceID

spring.cloud.zookeeper.dependency-configurations

  

spring.cloud.zookeeper.dependency-names

  

spring.cloud.zookeeper.discovery.enabled

true

 

spring.cloud.zookeeper.discovery.initial-status

 

The initial status of this instance (defaults to {@link StatusConstants#STATUS_UP}).

spring.cloud.zookeeper.discovery.instance-host

 

Predefined host with which a service can register itself in Zookeeper. Corresponds to the {code address} from the URI spec.

spring.cloud.zookeeper.discovery.instance-id

 

Id used to register with zookeeper. Defaults to a random UUID.

spring.cloud.zookeeper.discovery.instance-port

 

Port to register the service under (defaults to listening port)

spring.cloud.zookeeper.discovery.instance-ssl-port

 

Ssl port of the registered service.

spring.cloud.zookeeper.discovery.metadata

 

Gets the metadata name/value pairs associated with this instance. This information is sent to zookeeper and can be used by other instances.

spring.cloud.zookeeper.discovery.register

true

Register as a service in zookeeper.

spring.cloud.zookeeper.discovery.root

/services

Root Zookeeper folder in which all instances are registered

spring.cloud.zookeeper.discovery.uri-spec

{scheme}://{address}:{port}

The URI specification to resolve during service registration in Zookeeper

spring.cloud.zookeeper.enabled

true

Is Zookeeper enabled

spring.cloud.zookeeper.max-retries

10

Max number of times to retry

spring.cloud.zookeeper.max-sleep-ms

500

Max time in ms to sleep on each retry

spring.cloud.zookeeper.prefix

 

Common prefix that will be applied to all Zookeeper dependencies' paths

spring.integration.poller.fixed-delay

1000

Fixed delay for default poller.

spring.integration.poller.max-messages-per-poll

1

Maximum messages per poll for the default poller.

spring.sleuth.annotation.enabled

true

 

spring.sleuth.async.configurer.enabled

true

Enable default AsyncConfigurer.

spring.sleuth.async.enabled

true

Enable instrumenting async related components so that the tracing information is passed between threads.

spring.sleuth.enabled

true

 

spring.sleuth.feign.enabled

true

Enable span information propagation when using Feign.

spring.sleuth.feign.processor.enabled

true

Enable post processor that wraps Feign Context in its tracing representations.

spring.sleuth.hystrix.strategy.enabled

true

Enable custom HystrixConcurrencyStrategy that wraps all Callable instances into their Sleuth representative - the TraceCallable.

spring.sleuth.integration.enabled

true

Enable Spring Integration sleuth instrumentation.

spring.sleuth.integration.patterns

*

An array of simple patterns against which channel names will be matched. Default is * (all channels). See org.springframework.util.PatternMatchUtils.simpleMatch(String, String).

spring.sleuth.integration.websockets.enabled

true

Enable tracing for WebSockets.

spring.sleuth.keys.async.class-name-key

class

Simple name of the class with a method annotated with {@code @Async} from which the asynchronous process started @see org.springframework.scheduling.annotation.Async

spring.sleuth.keys.async.method-name-key

method

Name of the method annotated with {@code @Async} @see org.springframework.scheduling.annotation.Async

spring.sleuth.keys.async.prefix

 

Prefix for header names if they are added as tags.

spring.sleuth.keys.async.thread-name-key

thread

Name of the thread that executed the async method @see org.springframework.scheduling.annotation.Async

spring.sleuth.keys.http.headers

 

Additional headers that should be added as tags if they exist. If the header value is multi-valued, the tag value will be a comma-separated, single-quoted list.

spring.sleuth.keys.http.host

http.host

The domain portion of the URL or host header. Example: "mybucket.s3.amazonaws.com". Used to filter by host as opposed to ip address.

spring.sleuth.keys.http.method

http.method

The HTTP method, or verb, such as "GET" or "POST". Used to filter against an http route.

spring.sleuth.keys.http.path

http.path

The absolute http path, without any query parameters. Example: "/objects/abcd-ff". Used to filter against an http route, portably with zipkin v1. In zipkin v1, only equals filters are supported. Dropping query parameters makes the number of distinct URIs less. For example, one can query for the same resource, regardless of signing parameters encoded in the query line. This does not reduce cardinality to a HTTP single route. For example, it is common to express a route as an http URI template like "/resource/{resource_id}". In systems where only equals queries are available, searching for {@code http.uri=/resource} won’t match if the actual request was "/resource/abcd-ff". Historical note: This was commonly expressed as "http.uri" in zipkin, eventhough it was most often just a path.

spring.sleuth.keys.http.prefix

http.

Prefix for header names if they are added as tags.

spring.sleuth.keys.http.request-size

http.request.size

The size of the non-empty HTTP request body, in bytes. Ex. "16384" <p>Large uploads can exceed limits or contribute directly to latency.

spring.sleuth.keys.http.response-size

http.response.size

The size of the non-empty HTTP response body, in bytes. Ex. "16384" <p>Large downloads can exceed limits or contribute directly to latency.

spring.sleuth.keys.http.status-code

http.status_code

The HTTP response code, when not in 2xx range. Ex. "503" Used to filter for error status. 2xx range are not logged as success codes are less interesting for latency troubleshooting. Omitting saves at least 20 bytes per span.

spring.sleuth.keys.http.url

http.url

The entire URL, including the scheme, host and query parameters if available. Ex. "https://mybucket.s3.amazonaws.com/objects/abcd-ff?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Algorithm=AWS4-HMAC-SHA256…​" Combined with {@link #method}, you can understand the fully-qualified request line. This is optional as it may include private data or be of considerable length.

spring.sleuth.keys.hystrix.command-group

commandGroup

Name of the command group. Hystrix uses the command group key to group together commands such as for reporting, alerting, dashboards, or team/library ownership. @see com.netflix.hystrix.HystrixCommandGroupKey

spring.sleuth.keys.hystrix.command-key

commandKey

Name of the command key. Describes the name for the given command. A key to represent a {@link com.netflix.hystrix.HystrixCommand} for monitoring, circuit-breakers, metrics publishing, caching and other such uses. @see com.netflix.hystrix.HystrixCommandKey

spring.sleuth.keys.hystrix.prefix

 

Prefix for header names if they are added as tags.

spring.sleuth.keys.hystrix.thread-pool-key

threadPoolKey

Name of the thread pool key. The thread-pool key represents a {@link com.netflix.hystrix.HystrixThreadPool} for monitoring, metrics publishing, caching, and other such uses. A {@link com.netflix.hystrix.HystrixCommand} is associated with a single {@link com.netflix.hystrix.HystrixThreadPool} as retrieved by the {@link com.netflix.hystrix.HystrixThreadPoolKey} injected into it, or it defaults to one created using the {@link com.netflix.hystrix.HystrixCommandGroupKey} it is created with. @see com.netflix.hystrix.HystrixThreadPoolKey

spring.sleuth.keys.message.headers

 

Additional headers that should be added as tags if they exist. If the header value is not a String it will be converted to a String using its toString() method.

spring.sleuth.keys.message.payload.size

message/payload-size

An estimate of the size of the payload if available.

spring.sleuth.keys.message.payload.type

message/payload-type

The type of the payload.

spring.sleuth.keys.message.prefix

message/

Prefix for header names if they are added as tags.

spring.sleuth.keys.mvc.controller-class

mvc.controller.class

The lower case, hyphen delimited name of the class that processes the request. Ex. class named "BookController" will result in "book-controller" tag value.

spring.sleuth.keys.mvc.controller-method

mvc.controller.method

The lower case, hyphen delimited name of the class that processes the request. Ex. method named "listOfBooks" will result in "list-of-books" tag value.

spring.sleuth.log.slf4j.enabled

true

Enable a {@link Slf4jSpanLogger} that prints tracing information in the logs.

spring.sleuth.log.slf4j.name-skip-pattern

 

Name pattern for which span should not be printed in the logs.

spring.sleuth.metric.enabled

true

Enable calculation of accepted and dropped spans through {@link org.springframework.boot.actuate.metrics.CounterService}

spring.sleuth.metric.span.accepted-name

counter.span.accepted

 

spring.sleuth.metric.span.dropped-name

counter.span.dropped

 

spring.sleuth.rxjava.schedulers.hook.enabled

true

Enable support for RxJava via RxJavaSchedulersHook.

spring.sleuth.rxjava.schedulers.ignoredthreads

[HystrixMetricPoller, ^RxComputation.*$]

Thread names for which spans will not be sampled.

spring.sleuth.sampler.percentage

0.1

Percentage of requests that should be sampled. E.g. 1.0 - 100% requests should be sampled. The precision is whole-numbers only (i.e. there’s no support for 0.1% of the traces).

spring.sleuth.scheduled.enabled

true

Enable tracing for {@link org.springframework.scheduling.annotation.Scheduled}.

spring.sleuth.scheduled.skip-pattern

 

Pattern for the fully qualified name of a class that should be skipped.

spring.sleuth.supports-join

true

When true, your tracing system allows sharing a span ID between a client and server span

spring.sleuth.trace-id128

false

When true, generate 128-bit trace IDs instead of 64-bit ones.

spring.sleuth.web.client.enabled

true

Enable interceptor injecting into {@link org.springframework.web.client.RestTemplate}

spring.sleuth.web.enabled

true

When true enables instrumentation for web applications

spring.sleuth.web.filter-order

 

Order in which the {@link TraceFilter} should be registered. Defaults to {@link TraceFilter#ORDER}

spring.sleuth.web.skip-pattern

/api-docs.*

/autoconfig

/configprops

/dump

/health

/info

/metrics.*

/mappings

/trace

/swagger.*

.*\.png

.*\.css

.*\.js

.*\.html

/favicon.ico

/hystrix.stream

Pattern for URLs that should be skipped in tracing

spring.sleuth.zuul.enabled

true

Enable span information propagation when using Zuul.

stubrunner.classifier

stubs

The classifier to use by default in ivy co-ordinates for a stub.

stubrunner.consumer-name

 

You can override the default {@code spring.application.name} of this field by setting a value to this parameter.

stubrunner.ids

[]

The ids of the stubs to run in "ivy" notation ([groupId]:artifactId:[version]:[classifier][:port]). {@code groupId}, {@code classifier}, {@code version} and {@code port} can be optional.

stubrunner.ids-to-service-ids

 

Mapping of Ivy notation based ids to serviceIds inside your application Example "a:b" → "myService" "artifactId" → "myOtherService"

stubrunner.mappings-output-folder

 

Dumps the mappings of each HTTP server to the selected folder

stubrunner.max-port

15000

Max value of a port for the automatically started WireMock server

stubrunner.min-port

10000

Min value of a port for the automatically started WireMock server

stubrunner.password

 

Repository password

stubrunner.proxy-host

 

Repository proxy host

stubrunner.proxy-port

 

Repository proxy port

stubrunner.repository-root

 

The repository root to use (where the stubs should be downloaded from)

stubrunner.stubs-per-consumer

false

Should only stubs for this particular consumer get registered in HTTP server stub.

stubrunner.username

 

Repository username

stubrunner.work-offline

false

Should the stubs be checked for presence only locally

turbine.stream.enabled

true

Enables Autoconfiguration for a Spring Cloud Turbine using Spring Cloud Stream.

zuul.add-host-header

false

Flag to determine whether the proxy forwards the Host header.

zuul.add-proxy-headers

true

Flag to determine whether the proxy adds X-Forwarded-* headers.

zuul.force-original-query-string-encoding

false

Flag to force the original query string encoding when building the backend URI in SimpleHostRoutingFilter. When activated, query string will be built using HttpServletRequest getQueryString() method instead of UriTemplate. Note that this flag is not used in RibbonRoutingFilter with services found via DiscoveryClient (like Eureka).

zuul.host.connect-timeout-millis

2000

The connection timeout in millis. Defaults to 2000.

zuul.host.max-per-route-connections

20

The maximum number of connections that can be used by a single route.

zuul.host.max-total-connections

200

The maximum number of total connections the proxy can hold open to backends.

zuul.host.socket-timeout-millis

10000

The socket timeout in millis. Defaults to 10000.

zuul.host.time-to-live

-1

The lifetime for the connection pool.

zuul.host.time-unit

 

The time unit for timeToLive.

zuul.ignore-local-service

true

 

zuul.ignore-security-headers

true

Flag to say that SECURITY_HEADERS are added to ignored headers if spring security is on the classpath. By setting ignoreSecurityHeaders to false we can switch off this default behaviour. This should be used together with disabling the default spring security headers see https://docs.spring.io/spring-security/site/docs/current/reference/html/headers.html#default-security-headers

zuul.ignored-headers

 

Names of HTTP headers to ignore completely (i.e. leave them out of downstream requests and drop them from downstream responses).

zuul.ignored-patterns

  

zuul.ignored-services

 

Set of service names not to consider for proxying automatically. By default all services in the discovery client will be proxied.

zuul.include-debug-header

false

Setting for SendResponseFilter to conditionally include X-Zuul-Debug-Header header.

zuul.initial-stream-buffer-size

8192

Setting for SendResponseFilter for the initial stream buffer size.

zuul.prefix

 

A common prefix for all routes.

zuul.remove-semicolon-content

true

Flag to say that path elements past the first semicolon can be dropped.

zuul.retryable

false

Flag for whether retry is supported by default (assuming the routes themselves support it).

zuul.ribbon-isolation-strategy

  

zuul.ribbon.eager-load.enabled

false

Enables eager loading of Ribbon clients on startup.

zuul.routes

 

Map of route names to properties.

zuul.semaphore.max-semaphores

100

The maximum number of total semaphores for Hystrix.

zuul.sensitive-headers

 

List of sensitive headers that are not passed to downstream requests. Defaults to a "safe" set of headers that commonly contain user credentials. It’s OK to remove those from the list if the downstream service is part of the same system as the proxy, so they are sharing authentication data. If using a physical URL outside your own domain, then generally it would be a bad idea to leak user credentials.

zuul.servlet-path

/zuul

Path to install Zuul as a servlet (not part of Spring MVC). The servlet is more memory efficient for requests with large bodies, e.g. file uploads.

zuul.set-content-length

false

Setting for SendResponseFilter to conditionally set Content-Length header.

zuul.ssl-hostname-validation-enabled

true

Flag to say whether the hostname for ssl connections should be verified or not. Default is true. This should only be used in test setups!

zuul.strip-prefix

true

Flag saying whether to strip the prefix from the path before forwarding.

zuul.thread-pool.thread-pool-key-prefix

 

A prefix for HystrixThreadPoolKey of hystrix’s thread pool that is allocated to each service Id. This property is only applicable when using THREAD as ribbonIsolationStrategy and useSeparateThreadPools = true

zuul.thread-pool.use-separate-thread-pools

false

Flag to determine whether RibbonCommands should use separate thread pools for hystrix. By setting to true, RibbonCommands will be executed in a hystrix’s thread pool that it is associated with. Each RibbonCommand will be associated with a thread pool according to its commandKey (serviceId). As default, all commands will be executed in a single thread pool whose threadPoolKey is "RibbonCommand". This property is only applicable when using THREAD as ribbonIsolationStrategy

zuul.trace-request-body

true

Flag to say that request bodies can be traced.

\ No newline at end of file diff --git a/Edgware.SR6/spring-cloud.xml b/Edgware.SR6/spring-cloud.xml new file mode 100644 index 00000000..0cefcb5b --- /dev/null +++ b/Edgware.SR6/spring-cloud.xml @@ -0,0 +1,25700 @@ + + + + + +Spring Cloud +2019-05-28 + + + +Spring Cloud provides tools for developers to quickly build some of +the common patterns in distributed systems (e.g. configuration +management, service discovery, circuit breakers, intelligent routing, +micro-proxy, control bus). Coordination of +distributed systems leads to boiler plate patterns, and using Spring +Cloud developers can quickly stand up services and applications that +implement those patterns. They will work well in any distributed +environment, including the developer’s own laptop, bare metal data +centres, and managed platforms such as Cloud Foundry. +Version: 1.3.8.RELEASE + + +Features +Spring Cloud focuses on providing good out of box experience for typical use cases +and extensibility mechanism to cover others. + + +Distributed/versioned configuration + + +Service registration and discovery + + +Routing + + +Service-to-service calls + + +Load balancing + + +Circuit Breakers + + +Distributed messaging + + + + +Cloud Native Applications + +Cloud Native is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development. A related discipline is that of building 12-factor Apps in which development practices are aligned with delivery and operations goals, for instance by using declarative programming and management and monitoring. Spring Cloud facilitates these styles of development in a number of specific ways and the starting point is a set of features that all components in a distributed system either need or need easy access to when required. +Many of those features are covered by Spring Boot, which we build on in Spring Cloud. Some more are delivered by Spring Cloud as two libraries: Spring Cloud Context and Spring Cloud Commons. Spring Cloud Context provides utilities and special services for the ApplicationContext of a Spring Cloud application (bootstrap context, encryption, refresh scope and environment endpoints). Spring Cloud Commons is a set of abstractions and common classes used in different Spring Cloud implementations (eg. Spring Cloud Netflix vs. Spring Cloud Consul). +If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information: + + +Java 6 JCE + + +Java 7 JCE + + +Java 8 JCE + + +Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using). + +Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. + + + +Spring Cloud Context: Application Context Services +Spring Boot has an opinionated view of how to build an application +with Spring: for instance it has conventional locations for common +configuration file, and endpoints for common management and monitoring +tasks. Spring Cloud builds on top of that and adds a few features that +probably all components in a system would use or occasionally need. +
+The Bootstrap Application Context +A Spring Cloud application operates by creating a "bootstrap" +context, which is a parent context for the main application. Out of +the box it is responsible for loading configuration properties from +the external sources, and also decrypting properties in the local +external configuration files. The two contexts share an Environment +which is the source of external properties for any Spring +application. Bootstrap properties (not bootstrap.properties but properties + that are loaded during the bootstrap phase) are added with high precedence, so +they cannot be overridden by local configuration, by default. +The bootstrap context uses a different convention for locating +external configuration than the main application context, so instead +of application.yml (or .properties) you use bootstrap.yml, +keeping the external configuration for bootstrap and main context +nicely separate. Example: + +bootstrap.yml + +spring: + application: + name: foo + cloud: + config: + uri: ${SPRING_CONFIG_URI:http://localhost:8888} + + +It is a good idea to set the spring.application.name (in +bootstrap.yml or application.yml) if your application needs any +application-specific configuration from the server. +You can disable the bootstrap process completely by setting +spring.cloud.bootstrap.enabled=false (e.g. in System properties). +
+
+Application Context Hierarchies +If you build an application context from SpringApplication or +SpringApplicationBuilder, then the Bootstrap context is added as a +parent to that context. It is a feature of Spring that child contexts +inherit property sources and profiles from their parent, so the "main" +application context will contain additional property sources, compared +to building the same context without Spring Cloud Config. The +additional property sources are: + + +"bootstrap": an optional CompositePropertySource appears with high +priority if any PropertySourceLocators are found in the Bootstrap +context, and they have non-empty properties. An example would be +properties from the Spring Cloud Config Server. See +below for instructions +on how to customize the contents of this property source. + + +"applicationConfig: [classpath:bootstrap.yml]" (and friends if +Spring profiles are active). If you have a bootstrap.yml (or +properties) then those properties are used to configure the Bootstrap +context, and then they get added to the child context when its parent +is set. They have lower precedence than the application.yml (or +properties) and any other property sources that are added to the child +as a normal part of the process of creating a Spring Boot +application. See below for +instructions on how to customize the contents of these property +sources. + + +Because of the ordering rules of property sources the "bootstrap" +entries take precedence, but note that these do not contain any data +from bootstrap.yml, which has very low precedence, but can be used +to set defaults. +You can extend the context hierarchy by simply setting the parent +context of any ApplicationContext you create, e.g. using its own +interface, or with the SpringApplicationBuilder convenience methods +(parent(), child() and sibling()). The bootstrap context will be +the parent of the most senior ancestor that you create yourself. +Every context in the hierarchy will have its own "bootstrap" property +source (possibly empty) to avoid promoting values inadvertently from +parents down to their descendants. Every context in the hierarchy can +also (in principle) have a different spring.application.name and +hence a different remote property source if there is a Config +Server. Normal Spring application context behaviour rules apply to +property resolution: properties from a child context override those in +the parent, by name and also by property source name (if the child has +a property source with the same name as the parent, the one from the +parent is not included in the child). +Note that the SpringApplicationBuilder allows you to share an +Environment amongst the whole hierarchy, but that is not the +default. Thus, sibling contexts in particular do not need to have the +same profiles or property sources, even though they will share common +things with their parent. +
+
+Changing the Location of Bootstrap Properties +The bootstrap.yml (or .properties) location can be specified using +spring.cloud.bootstrap.name (default "bootstrap") or +spring.cloud.bootstrap.location (default empty), e.g. in System +properties. Those properties behave like the spring.config.* +variants with the same name, in fact they are used to set up the +bootstrap ApplicationContext by setting those properties in its +Environment. If there is an active profile (from +spring.profiles.active or through the Environment API in the +context you are building) then properties in that profile will be +loaded as well, just like in a regular Spring Boot app, e.g. from +bootstrap-development.properties for a "development" profile. +
+
+Overriding the Values of Remote Properties +The property sources that are added to you application by the +bootstrap context are often "remote" (e.g. from a Config Server), and +by default they cannot be overridden locally, except on the command +line. If you want to allow your applications to override the remote +properties with their own System properties or config files, the +remote property source has to grant it permission by setting +spring.cloud.config.allowOverride=true (it doesn’t work to set this +locally). Once that flag is set there are some finer grained settings +to control the location of the remote properties in relation to System +properties and the application’s local configuration: +spring.cloud.config.overrideNone=true to override with any local +property source, and +spring.cloud.config.overrideSystemProperties=false if only System +properties and env vars should override the remote settings, but not +the local config files. +
+
+Customizing the Bootstrap Configuration +The bootstrap context can be trained to do anything you like by adding +entries to /META-INF/spring.factories under the key +org.springframework.cloud.bootstrap.BootstrapConfiguration. This is +a comma-separated list of Spring @Configuration classes which will +be used to create the context. Any beans that you want to be available +to the main application context for autowiring can be created here, +and also there is a special contract for @Beans of type +ApplicationContextInitializer. Classes can be marked with an @Order +if you want to control the startup sequence (the default order is +"last"). + +Be careful when adding custom BootstrapConfiguration that the +classes you add are not @ComponentScanned by mistake into your +"main" application context, where they might not be needed. +Use a separate package name for boot configuration classes that is +not already covered by your @ComponentScan or @SpringBootApplication +annotated configuration classes. + +The bootstrap process ends by injecting initializers into the main +SpringApplication instance (i.e. the normal Spring Boot startup +sequence, whether it is running as a standalone app or deployed in an +application server). First a bootstrap context is created from the +classes found in spring.factories and then all @Beans of type +ApplicationContextInitializer are added to the main +SpringApplication before it is started. +
+
+Customizing the Bootstrap Property Sources +The default property source for external configuration added by the +bootstrap process is the Config Server, but you can add additional +sources by adding beans of type PropertySourceLocator to the +bootstrap context (via spring.factories). You could use this to +insert additional properties from a different server, or from a +database, for instance. +As an example, consider the following trivial custom locator: +@Configuration +public class CustomPropertySourceLocator implements PropertySourceLocator { + + @Override + public PropertySource<?> locate(Environment environment) { + return new MapPropertySource("customProperty", + Collections.<String, Object>singletonMap("property.from.sample.custom.source", "worked as intended")); + } + +} +The Environment that is passed in is the one for the +ApplicationContext about to be created, i.e. the one that we are +supplying additional property sources for. It will already have its +normal Spring Boot-provided property sources, so you can use those to +locate a property source specific to this Environment (e.g. by +keying it on the spring.application.name, as is done in the default +Config Server property source locator). +If you create a jar with this class in it and then add a +META-INF/spring.factories containing: +org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator +then the "customProperty" PropertySource will show up in any +application that includes that jar on its classpath. +
+
+Logging Configuration +If you are going to use Spring Boot to configure log settings than +you should place this configuration in `bootstrap.[yml | properties] +if you would like it to apply to all events. +
+
+Environment Changes +The application will listen for an EnvironmentChangeEvent and react +to the change in a couple of standard ways (additional +ApplicationListeners can be added as @Beans by the user in the +normal way). When an EnvironmentChangeEvent is observed it will +have a list of key values that have changed, and the application will +use those to: + + +Re-bind any @ConfigurationProperties beans in the context + + +Set the logger levels for any properties in logging.level.* + + +Note that the Config Client does not by default poll for changes in +the Environment, and generally we would not recommend that approach +for detecting changes (although you could set it up with a +@Scheduled annotation). If you have a scaled-out client application +then it is better to broadcast the EnvironmentChangeEvent to all +the instances instead of having them polling for changes (e.g. using +the Spring Cloud +Bus). +The EnvironmentChangeEvent covers a large class of refresh use +cases, as long as you can actually make a change to the Environment +and publish the event (those APIs are public and part of core +Spring). You can verify the changes are bound to +@ConfigurationProperties beans by visiting the /configprops +endpoint (normal Spring Boot Actuator feature). For instance a +DataSource can have its maxPoolSize changed at runtime (the +default DataSource created by Spring Boot is an +@ConfigurationProperties bean) and grow capacity +dynamically. Re-binding @ConfigurationProperties does not cover +another large class of use cases, where you need more control over the +refresh, and where you need a change to be atomic over the whole +ApplicationContext. To address those concerns we have +@RefreshScope. +
+
+Refresh Scope +A Spring @Bean that is marked as @RefreshScope will get special +treatment when there is a configuration change. This addresses the +problem of stateful beans that only get their configuration injected +when they are initialized. For instance if a DataSource has open +connections when the database URL is changed via the Environment, we +probably want the holders of those connections to be able to complete +what they are doing. Then the next time someone borrows a connection +from the pool he gets one with the new URL. +Refresh scope beans are lazy proxies that initialize when they are +used (i.e. when a method is called), and the scope acts as a cache of +initialized values. To force a bean to re-initialize on the next +method call you just need to invalidate its cache entry. +The RefreshScope is a bean in the context and it has a public method +refreshAll() to refresh all beans in the scope by clearing the +target cache. There is also a refresh(String) method to refresh an +individual bean by name. This functionality is exposed in the +/refresh endpoint (over HTTP or JMX). + +@RefreshScope works (technically) on an @Configuration +class, but it might lead to surprising behaviour: e.g. it does not +mean that all the @Beans defined in that class are themselves +@RefreshScope. Specifically, anything that depends on those beans +cannot rely on them being updated when a refresh is initiated, unless +it is itself in @RefreshScope (in which it will be rebuilt on a +refresh and its dependencies re-injected, at which point they will be +re-initialized from the refreshed @Configuration). + +
+
+Encryption and Decryption +Spring Cloud has an Environment pre-processor for decrypting +property values locally. It follows the same rules as the Config +Server, and has the same external configuration via encrypt.*. Thus +you can use encrypted values in the form {cipher}* and as long as +there is a valid key then they will be decrypted before the main +application context gets the Environment. To use the encryption +features in an application you need to include Spring Security RSA in +your classpath (Maven co-ordinates +"org.springframework.security:spring-security-rsa") and you also need +the full strength JCE extensions in your JVM. +If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information: + + +Java 6 JCE + + +Java 7 JCE + + +Java 8 JCE + + +Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using). +
+
+Endpoints +For a Spring Boot Actuator application there are some additional management endpoints: + + +POST to /env to update the Environment and rebind @ConfigurationProperties and log levels + + +/refresh for re-loading the boot strap context and refreshing the @RefreshScope beans + + +/restart for closing the ApplicationContext and restarting it (disabled by default) + + +/pause and /resume for calling the Lifecycle methods (stop() and start() on the ApplicationContext) + + + +If you disable the /restart endpoint then the /pause and /resume endpoints +will also be disabled since they are just a special case of /restart. + +
+ + +Spring Cloud Commons: Common Abstractions +Patterns such as service discovery, load balancing and circuit breakers lend themselves to a common abstraction layer that can be consumed by all Spring Cloud clients, independent of the implementation (e.g. discovery via Eureka or Consul). +
+@EnableDiscoveryClient +Commons provides the @EnableDiscoveryClient annotation. This looks for implementations of the DiscoveryClient interface via META-INF/spring.factories. Implementations of Discovery Client will add a configuration class to spring.factories under the org.springframework.cloud.client.discovery.EnableDiscoveryClient key. Examples of DiscoveryClient implementations: are Spring Cloud Netflix Eureka, Spring Cloud Consul Discovery and Spring Cloud Zookeeper Discovery. +By default, implementations of DiscoveryClient will auto-register the local Spring Boot server with the remote discovery server. This can be disabled by setting autoRegister=false in @EnableDiscoveryClient. + +The use of @EnableDiscoveryClient is no longer required. It is enough to just have a DiscoveryClient implementation +on the classpath to cause the Spring Boot application to register with the service discovery server. + +
+Health Indicator +Commons creates a Spring Boot HealthIndicator that DiscoveryClient implementations can participate in by implementing DiscoveryHealthIndicator. To disable the composite HealthIndicator set spring.cloud.discovery.client.composite-indicator.enabled=false. A generic HealthIndicator based on DiscoveryClient is auto-configured (DiscoveryClientHealthIndicator). To disable it, set `spring.cloud.discovery.client.health-indicator.enabled=false. To disable the description field of the DiscoveryClientHealthIndicator set spring.cloud.discovery.client.health-indicator.include-description=false, otherwise it can bubble up as the description of the rolled up HealthIndicator. +
+
+
+ServiceRegistry +Commons now provides a ServiceRegistry interface which provides methods like register(Registration) and deregister(Registration) which allow you to provide custom registered services. Registration is a marker interface. +@Configuration +@EnableDiscoveryClient(autoRegister=false) +public class MyConfiguration { + private ServiceRegistry registry; + + public MyConfiguration(ServiceRegistry registry) { + this.registry = registry; + } + + // called via some external process, such as an event or a custom actuator endpoint + public void register() { + Registration registration = constructRegistration(); + this.registry.register(registration); + } +} +Each ServiceRegistry implementation has its own Registry implementation. + + +ZookeeperRegistration used with ZookeeperServiceRegistry + + +EurekaRegistration used with EurekaServiceRegistry + + +ConsulRegistration used with ConsulServiceRegistry + + +If you are using the ServiceRegistry interface, you are going to need to pass the +correct Registry implementation for the ServiceRegistry implementation you +are using. +
+ServiceRegistry Auto-Registration +By default, the ServiceRegistry implementation will auto-register the running service. To disable that behavior, there are two methods. You can set @EnableDiscoveryClient(autoRegister=false) to permanently disable auto-registration. You can also set spring.cloud.service-registry.auto-registration.enabled=false to disable the behavior via configuration. +
+
+Service Registry Actuator Endpoint +A /service-registry actuator endpoint is provided by Commons. This endpoint relys on a Registration bean in the Spring Application Context. Calling /service-registry/instance-status via a GET will return the status of the Registration. A POST to the same endpoint with a String body will change the status of the current Registration to the new value. Please see the documentation of the ServiceRegistry implementation you are using for the allowed values for updating the status and the values retured for the status. +
+
+
+Spring RestTemplate as a Load Balancer Client +RestTemplate can be automatically configured to use ribbon. To create a load balanced RestTemplate create a RestTemplate @Bean and use the @LoadBalanced qualifier. + +A RestTemplate bean is no longer created via auto configuration. It must be created by individual applications. + +@Configuration +public class MyConfiguration { + + @LoadBalanced + @Bean + RestTemplate restTemplate() { + return new RestTemplate(); + } +} + +public class MyClass { + @Autowired + private RestTemplate restTemplate; + + public String doOtherStuff() { + String results = restTemplate.getForObject("http://stores/stores", String.class); + return results; + } +} +The URI needs to use a virtual host name (ie. service name, not a host name). +The Ribbon client is used to create a full physical address. See +RibbonAutoConfiguration +for details of how the RestTemplate is set up. +
+Retrying Failed Requests +A load balanced RestTemplate can be configured to retry failed requests. +By default this logic is disabled, you can enable it by adding Spring Retry to your application’s classpath. The load balanced RestTemplate will +honor some of the Ribbon configuration values related to retrying failed requests. If +you would like to disable the retry logic with Spring Retry on the classpath +you can set spring.cloud.loadbalancer.retry.enabled=false. +The properties you can use are client.ribbon.MaxAutoRetries, +client.ribbon.MaxAutoRetriesNextServer, and client.ribbon.OkToRetryOnAllOperations. +See the Ribbon documentation +for a description of what there properties do. +If you would like to implement a BackOffPolicy in your retries you will need to +create a bean of type LoadBalancedBackOffPolicyFactory, and return the BackOffPolicy +you would like to use for a given service. +@Configuration +public class MyConfiguration { + @Bean + LoadBalancedBackOffPolicyFactory backOffPolciyFactory() { + return new LoadBalancedBackOffPolicyFactory() { + @Override + public BackOffPolicy createBackOffPolicy(String service) { + return new ExponentialBackOffPolicy(); + } + }; + } +} + +client in the above examples should be replaced with your Ribbon client’s +name. + +If you want to add one or more RetryListener to your retry you will need to +create a bean of type LoadBalancedRetryListenerFactory and return the RetryListener array +you would like to use for a given service. +@Configuration +public class MyConfiguration { + @Bean + LoadBalancedRetryListenerFactory retryListenerFactory() { + return new LoadBalancedRetryListenerFactory() { + @Override + public RetryListener[] createRetryListeners(String service) { + return new RetryListener[]{new RetryListener() { + @Override + public <T, E extends Throwable> boolean open(RetryContext context, RetryCallback<T, E> callback) { + //TODO Do you business... + return true; + } + + @Override + public <T, E extends Throwable> void close(RetryContext context, RetryCallback<T, E> callback, Throwable throwable) { + //TODO Do you business... + } + + @Override + public <T, E extends Throwable> void onError(RetryContext context, RetryCallback<T, E> callback, Throwable throwable) { + //TODO Do you business... + } + }}; + } + }; + } +} +
+
+
+Multiple RestTemplate objects +If you want a RestTemplate that is not load balanced, create a RestTemplate +bean and inject it as normal. To access the load balanced RestTemplate use +the @LoadBalanced qualifier when you create your @Bean. + +Notice the @Primary annotation on the plain RestTemplate declaration in the example below, to disambiguate the unqualified @Autowired injection. + +@Configuration +public class MyConfiguration { + + @LoadBalanced + @Bean + RestTemplate loadBalanced() { + return new RestTemplate(); + } + + @Primary + @Bean + RestTemplate restTemplate() { + return new RestTemplate(); + } +} + +public class MyClass { + @Autowired + private RestTemplate restTemplate; + + @Autowired + @LoadBalanced + private RestTemplate loadBalanced; + + public String doOtherStuff() { + return loadBalanced.getForObject("http://stores/stores", String.class); + } + + public String doStuff() { + return restTemplate.getForObject("https://example.com", String.class); + } +} + +If you see errors like java.lang.IllegalArgumentException: Can not set org.springframework.web.client.RestTemplate field com.my.app.Foo.restTemplate to com.sun.proxy.$Proxy89 try injecting RestOperations instead or setting spring.aop.proxyTargetClass=true. + +
+
+Ignore Network Interfaces +Sometimes it is useful to ignore certain named network interfaces so they can be excluded from Service Discovery registration (eg. running in a Docker container). A list of regular expressions can be set that will cause the desired network interfaces to be ignored. The following configuration will ignore the "docker0" interface and all interfaces that start with "veth". + +application.yml + +spring: + cloud: + inetutils: + ignoredInterfaces: + - docker0 + - veth.* + + +You can also force to use only specified network addresses using list of regular expressions: + +bootstrap.yml + +spring: + cloud: + inetutils: + preferredNetworks: + - 192.168 + - 10.0 + + +You can also force to use only site local addresses. See Inet4Address.html.isSiteLocalAddress() for more details what is site local address. + +application.yml + +spring: + cloud: + inetutils: + useOnlySiteLocalInterfaces: true + + +
+
+HTTP Client Factories +Spring Cloud Commons provides beans for creating both Apache HTTP clients (ApacheHttpClientFactory) +as well as OK HTTP clients (OkHttpClientFactory). The OkHttpClientFactory bean will only be created +if the OK HTTP jar is on the classpath. In addition, Spring Cloud Commons provides beans for creating +the connection managers used by both clients, ApacheHttpClientConnectionManagerFactory for the Apache +HTTP client and OkHttpClientConnectionPoolFactory for the OK HTTP client. You can provide +your own implementation of these beans if you would like to customize how the HTTP clients are created +in downstream projects. You can also disable the creation of these beans by setting +spring.cloud.httpclientfactories.apache.enabled or spring.cloud.httpclientfactories.ok.enabled to +false. +
+
+Spring Cloud Compatibility Verification +Due to the fact that some users have problem with setting up Spring Cloud application, we’ve decided +to add a compatibility verification mechanism. It will break if your current setup is not compatible +with Spring Cloud requirements, together with a report, showing what exactly went wrong. +At the moment we verify which version of Spring Boot is added to your classpath. +Example of a report +*************************** +APPLICATION FAILED TO START +*************************** + +Description: + +Your project setup is incompatible with our requirements due to following reasons: + +- Spring Boot [1.5.16.RELEASE] is not compatible with this Spring Cloud release train + + +Action: + +Consider applying the following actions: + +- Change Spring Boot version to one of the following versions [1.2.x, 1.3.x] . +You can find the latest Spring Boot versions here [https://spring.io/projects/spring-boot#learn]. +If you want to learn more about the Spring Cloud Release train compatibility, you can visit this page [https://spring.io/projects/spring-cloud#overview] and check the [Release Trains] section. +In order to disable this feature, set spring.cloud.compatibility-verifier.enabled to false. +If you want to override the compatible Spring Boot versions, just set the +spring.cloud.compatibility-verifier.compatible-boot-versions property with a comma separated list +of compatible Spring Boot versions. +
+ + + +Spring Cloud Config + +1.3.8.RELEASE +Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With the Config Server you have a central place to manage external properties for applications across all environments. The concepts on both client and server map identically to the Spring Environment and PropertySource abstractions, so they fit very well with Spring applications, but can be used with any application running in any language. As an application moves through the deployment pipeline from dev to test and into production you can manage the configuration between those environments and be certain that applications have everything they need to run when they migrate. The default implementation of the server storage backend uses git so it easily supports labelled versions of configuration environments, as well as being accessible to a wide range of tooling for managing the content. It is easy to add alternative implementations and plug them in with Spring configuration. + + +Quick Start +Start the server: +$ cd spring-cloud-config-server +$ ../mvnw spring-boot:run +The server is a Spring Boot application so you can run it from your +IDE instead if you prefer (the main class is +ConfigServerApplication). Then try out a client: +$ curl localhost:8888/foo/development +{"name":"foo","label":"master","propertySources":[ + {"name":"https://github.com/scratches/config-repo/foo-development.properties","source":{"bar":"spam"}}, + {"name":"https://github.com/scratches/config-repo/foo.properties","source":{"foo":"bar"}} +]} +The default strategy for locating property sources is to clone a git +repository (at spring.cloud.config.server.git.uri) and use it to +initialize a mini SpringApplication. The mini-application’s +Environment is used to enumerate property sources and publish them +via a JSON endpoint. +The HTTP service has resources in the form: +/{application}/{profile}[/{label}] +/{application}-{profile}.yml +/{label}/{application}-{profile}.yml +/{application}-{profile}.properties +/{label}/{application}-{profile}.properties +where the "application" is injected as the spring.config.name in the +SpringApplication (i.e. what is normally "application" in a regular +Spring Boot app), "profile" is an active profile (or comma-separated +list of properties), and "label" is an optional git label (defaults to +"master".) +Spring Cloud Config Server pulls configuration for remote clients +from a git repository (which must be provided): +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo +
+Client Side Usage +To use these features in an application, just build it as a Spring +Boot application that depends on spring-cloud-config-client (e.g. see +the test cases for the config-client, or the sample app). The most +convenient way to add the dependency is via a Spring Boot starter +org.springframework.cloud:spring-cloud-starter-config. There is also a +parent pom and BOM (spring-cloud-starter-parent) for Maven users and a +Spring IO version management properties file for Gradle and Spring CLI +users. Example Maven configuration: + +pom.xml + + <parent> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-starter-parent</artifactId> + <version>1.5.10.RELEASE</version> + <relativePath /> <!-- lookup parent from repository --> + </parent> + +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>Edgware.SR2</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> +</dependencyManagement> + +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-config</artifactId> + </dependency> + <dependency> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-starter-test</artifactId> + <scope>test</scope> + </dependency> +</dependencies> + +<build> + <plugins> + <plugin> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-maven-plugin</artifactId> + </plugin> + </plugins> +</build> + + <!-- repositories also needed for snapshots and milestones --> + + +Then you can create a standard Spring Boot application, like this simple HTTP server: +@SpringBootApplication +@RestController +public class Application { + + @RequestMapping("/") + public String home() { + return "Hello World!"; + } + + public static void main(String[] args) { + SpringApplication.run(Application.class, args); + } + +} +When it runs it will pick up the external configuration from the +default local config server on port 8888 if it is running. To modify +the startup behaviour you can change the location of the config server +using bootstrap.properties (like application.properties but for +the bootstrap phase of an application context), e.g. +spring.cloud.config.uri: http://myconfigserver.com +The bootstrap properties will show up in the /env endpoint as a +high-priority property source, e.g. +$ curl localhost:8080/env +{ + "profiles":[], + "configService:https://github.com/spring-cloud-samples/config-repo/bar.properties":{"foo":"bar"}, + "servletContextInitParams":{}, + "systemProperties":{...}, + ... +} +(a property source called "configService:<URL of remote +repository>/<file name>" contains the property "foo" with value +"bar" and is highest priority). + +the URL in the property source name is the git repository not +the config server URL. + +
+ + +Spring Cloud Config Server +The Server provides an HTTP, resource-based API for external +configuration (name-value pairs, or equivalent YAML content). The +server is easily embeddable in a Spring Boot application using the +@EnableConfigServer annotation. So this app is a config server: + +ConfigServer.java + +@SpringBootApplication +@EnableConfigServer +public class ConfigServer { + public static void main(String[] args) { + SpringApplication.run(ConfigServer.class, args); + } +} + + +Like all Spring Boot apps it runs on port 8080 by default, but you +can switch it to the conventional port 8888 in various ways. The +easiest, which also sets a default configuration repository, +is by launching it with spring.config.name=configserver (there +is a configserver.yml in the Config Server jar). Another is +to use your own application.properties, e.g. + +application.properties + +server.port: 8888 +spring.cloud.config.server.git.uri: file://${user.home}/config-repo + + +where ${user.home}/config-repo is a git repository containing +YAML and properties files. + +in Windows you need an extra "/" in the file URL if it is +absolute with a drive prefix, e.g. file:///${user.home}/config-repo. + + +Here’s a recipe for creating the git repository in the example +above: +$ cd $HOME +$ mkdir config-repo +$ cd config-repo +$ git init . +$ echo info.foo: bar > application.properties +$ git add -A . +$ git commit -m "Add application.properties" + + +using the local filesystem for your git repository is +intended for testing only. Use a server to host your +configuration repositories in production. + + +the initial clone of your configuration repository will +be quick and efficient if you only keep text files in it. If you start +to store binary files, especially large ones, you may experience +delays on the first request for configuration and/or out of memory +errors in the server. + +
+Environment Repository +Where do you want to store the configuration data for the Config +Server? The strategy that governs this behaviour is the +EnvironmentRepository, serving Environment objects. This +Environment is a shallow copy of the domain from the Spring +Environment (including propertySources as the main feature). The +Environment resources are parametrized by three variables: + + +{application} maps to "spring.application.name" on the client side; + + +{profile} maps to "spring.profiles.active" on the client (comma separated list); and + + +{label} which is a server side feature labelling a "versioned" set of config files. + + +Repository implementations generally behave just like a Spring Boot +application loading configuration files from a "spring.config.name" +equal to the {application} parameter, and "spring.profiles.active" +equal to the {profiles} parameter. Precedence rules for profiles are +also the same as in a regular Boot application: active profiles take +precedence over defaults, and if there are multiple profiles the last +one wins (like adding entries to a Map). +Example: a client application has this bootstrap configuration: + +bootstrap.yml + +spring: + application: + name: foo + profiles: + active: dev,mysql + + +(as usual with a Spring Boot application, these properties could also +be set as environment variables or command line arguments). +If the repository is file-based, the server will create an +Environment from application.yml (shared between all clients), and +foo.yml (with foo.yml taking precedence). If the YAML files have +documents inside them that point to Spring profiles, those are applied +with higher precedence (in order of the profiles listed), and if +there are profile-specific YAML (or properties) files these are also +applied with higher precedence than the defaults. Higher precedence +translates to a PropertySource listed earlier in the +Environment. (These are the same rules as apply in a standalone +Spring Boot application.) +
+Git Backend +The default implementation of EnvironmentRepository uses a Git +backend, which is very convenient for managing upgrades and physical +environments, and also for auditing changes. To change the location of +the repository you can set the "spring.cloud.config.server.git.uri" +configuration property in the Config Server (e.g. in +application.yml). If you set it with a file: prefix it should work +from a local repository so you can get started quickly and easily +without a server, but in that case the server operates directly on the +local repository without cloning it (it doesn’t matter if it’s not +bare because the Config Server never makes changes to the "remote" +repository). To scale the Config Server up and make it highly +available, you would need to have all instances of the server pointing +to the same repository, so only a shared file system would work. Even +in that case it is better to use the ssh: protocol for a shared +filesystem repository, so that the server can clone it and use a local +working copy as a cache. +This repository implementation maps the {label} parameter of the +HTTP resource to a git label (commit id, branch name or tag). If the +git branch or tag name contains a slash ("/") then the label in the +HTTP URL should be specified with the special string "(_)" instead (to +avoid ambiguity with other URL paths). For example, if the label is +foo/bar, replacing the slash would result in a label that looks like +foo(_)bar. The inclusion of the special string "(_)" can also be +applied to the {application} parameter. Be careful with the brackets +in the URL if you are using a command line client like curl (e.g. +escape them from the shell with quotes ''). +
+Placeholders in Git URI +Spring Cloud Config Server supports a git repository URL with +placeholders for the {application} and {profile} (and {label} if +you need it, but remember that the label is applied as a git label +anyway). So you can easily support a "one repo per application" policy +using (for example): +spring: + cloud: + config: + server: + git: + uri: https://github.com/myorg/{application} +or a "one repo per profile" policy using a similar pattern but with +{profile}. +Additionally, using the special string "(_)" within your +{application} parameters can enable support for multiple +organizations (for example): +spring: + cloud: + config: + server: + git: + uri: https://github.com/{application} +where {application} is provided at request time in the format +"organization(_)application". +
+
+Pattern Matching and Multiple Repositories +There is also support for more complex requirements with pattern +matching on the application and profile name. The pattern format is a +comma-separated list of {application}/{profile} names with wildcards +(where a pattern beginning with a wildcard may need to be +quoted). Example: +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + repos: + simple: https://github.com/simple/config-repo + special: + pattern: special*/dev*,*special*/dev* + uri: https://github.com/special/config-repo + local: + pattern: local* + uri: file:/home/configsvc/config-repo +If {application}/{profile} does not match any of the patterns, it +will use the default uri defined under +"spring.cloud.config.server.git.uri". In the above example, for the +"simple" repository, the pattern is simple/* (i.e. it only matches +one application named "simple" in all profiles). The "local" +repository matches all application names beginning with "local" in all +profiles (the /* suffix is added automatically to any pattern that +doesn’t have a profile matcher). + +the "one-liner" short cut used in the "simple" example above can +only be used if the only property to be set is the URI. If you need to +set anything else (credentials, pattern, etc.) you need to use the full +form. + +The pattern property in the repo is actually an array, so you can +use a YAML array (or [0], [1], etc. suffixes in properties files) +to bind to multiple patterns. You may need to do this if you are going +to run apps with multiple profiles. Example: +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + repos: + development: + pattern: + - '*/development' + - '*/staging' + uri: https://github.com/development/config-repo + staging: + pattern: + - '*/qa' + - '*/production' + uri: https://github.com/staging/config-repo + +Spring Cloud will guess that a pattern containing a profile that +doesn’t end in * implies that you actually want to match a list of +profiles starting with this pattern (so */staging is a shortcut for +["*/staging", "*/staging,*"]). This is common where you need to run +apps in the "development" profile locally but also the "cloud" profile +remotely, for instance. + +Every repository can also optionally store config files in +sub-directories, and patterns to search for those directories can be +specified as searchPaths. For example at the top level: +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + searchPaths: foo,bar* +In this example the server searches for config files in the top level +and in the "foo/" sub-directory and also any sub-directory whose name +begins with "bar". +By default the server clones remote repositories when configuration +is first requested. The server can be configured to clone the repositories +at startup. For example at the top level: +spring: + cloud: + config: + server: + git: + uri: https://git/common/config-repo.git + repos: + team-a: + pattern: team-a-* + cloneOnStart: true + uri: https://git/team-a/config-repo.git + team-b: + pattern: team-b-* + cloneOnStart: false + uri: https://git/team-b/config-repo.git + team-c: + pattern: team-c-* + uri: https://git/team-a/config-repo.git +In this example the server clones team-a’s config-repo on startup before it +accepts any requests. All other repositories will not be cloned until +configuration from the repository is requested. + +Setting a repository to be cloned when the Config Server starts up can +help to identify a misconfigured configuration source (e.g., an invalid +repository URI) quickly, while the Config Server is starting up. With +cloneOnStart not enabled for a configuration source, the Config Server may +start successfully with a misconfigured or invalid configuration source and +not detect an error until an application requests configuration from that +configuration source. + +
+
+Authentication +To use HTTP basic authentication on the remote repository add the +"username" and "password" properties separately (not in the URL), +e.g. +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + username: trolley + password: strongpassword +If you don’t use HTTPS and user credentials, SSH should also work out +of the box when you store keys in the default directories (~/.ssh) +and the uri points to an SSH location, +e.g. "git@github.com:configuration/cloud-configuration". It is important that an entry for the Git server be present in the ~/.ssh/known_hosts file and that it is in ssh-rsa format. Other formats (like ecdsa-sha2-nistp256) are not supported. To avoid surprises, you should ensure that only one entry is present in the known_hosts file for the Git server and that it is matching with the URL you provided to the config server. If you used a hostname in the URL, you want to have exactly that in the known_hosts file, not the IP. +The repository is accessed using JGit, so any documentation you find on +that should be applicable. HTTPS proxy settings can be set in +~/.git/config or in the same way as for any other JVM process via +system properties (-Dhttps.proxyHost and -Dhttps.proxyPort). + +If you don’t know where your ~/.git directory is use git config +--global to manipulate the settings (e.g. git config --global +http.sslVerify false). + +
+
+Authentication with AWS CodeCommit +AWS CodeCommit authentication can also be +done. AWS CodeCommit uses an authentication helper when using Git from the command line. This helper is not +used with the JGit library, so a JGit CredentialProvider for AWS CodeCommit will be created if the Git +URI matches the AWS CodeCommit pattern. AWS CodeCommit URIs always look like +https://git-codecommit.${AWS_REGION}.amazonaws.com/${repopath}. +If you provide a username and password with an AWS CodeCommit URI, then these must be +the AWS accessKeyId and secretAccessKey +to be used to access the repository. If you do not specify a username and password, +then the accessKeyId and secretAccessKey will be retrieved using the +AWS Default Credential Provider Chain. +If your Git URI matches the CodeCommit URI pattern (above) then you must provide +valid AWS credentials in the username and password, or in one of the locations supported +by the default credential provider chain. AWS EC2 instances may use +IAM Roles for EC2 Instances. +Note: The aws-java-sdk-core jar is an optional dependency. If the aws-java-sdk-core jar is not on your +classpath, then the AWS Code Commit credential provider will not be created regardless of the git server URI. +
+
+Git SSH configuration using properties +By default, the JGit library used by Spring Cloud Config Server uses SSH configuration files such as ~/.ssh/known_hosts and /etc/ssh/ssh_config when connecting to Git repositories using an SSH URI. +In cloud environments such as Cloud Foundry, the local filesystem may be ephemeral or not easily accessible. For cases such as these, SSH configuration can be set using +Java properties. In order to activate property based SSH configuration, the property spring.cloud.config.server.git.ignoreLocalSshSettings must be set to true. +Example: + spring: + cloud: + config: + server: + git: + uri: git@gitserver.com:team/repo1.git + ignoreLocalSshSettings: true + hostKey: someHostKey + hostKeyAlgorithm: ssh-rsa + privateKey: | + -----BEGIN RSA PRIVATE KEY----- + MIIEpgIBAAKCAQEAx4UbaDzY5xjW6hc9jwN0mX33XpTDVW9WqHp5AKaRbtAC3DqX + IXFMPgw3K45jxRb93f8tv9vL3rD9CUG1Gv4FM+o7ds7FRES5RTjv2RT/JVNJCoqF + ol8+ngLqRZCyBtQN7zYByWMRirPGoDUqdPYrj2yq+ObBBNhg5N+hOwKjjpzdj2Ud + 1l7R+wxIqmJo1IYyy16xS8WsjyQuyC0lL456qkd5BDZ0Ag8j2X9H9D5220Ln7s9i + oezTipXipS7p7Jekf3Ywx6abJwOmB0rX79dV4qiNcGgzATnG1PkXxqt76VhcGa0W + DDVHEEYGbSQ6hIGSh0I7BQun0aLRZojfE3gqHQIDAQABAoIBAQCZmGrk8BK6tXCd + fY6yTiKxFzwb38IQP0ojIUWNrq0+9Xt+NsypviLHkXfXXCKKU4zUHeIGVRq5MN9b + BO56/RrcQHHOoJdUWuOV2qMqJvPUtC0CpGkD+valhfD75MxoXU7s3FK7yjxy3rsG + EmfA6tHV8/4a5umo5TqSd2YTm5B19AhRqiuUVI1wTB41DjULUGiMYrnYrhzQlVvj + 5MjnKTlYu3V8PoYDfv1GmxPPh6vlpafXEeEYN8VB97e5x3DGHjZ5UrurAmTLTdO8 + +AahyoKsIY612TkkQthJlt7FJAwnCGMgY6podzzvzICLFmmTXYiZ/28I4BX/mOSe + pZVnfRixAoGBAO6Uiwt40/PKs53mCEWngslSCsh9oGAaLTf/XdvMns5VmuyyAyKG + ti8Ol5wqBMi4GIUzjbgUvSUt+IowIrG3f5tN85wpjQ1UGVcpTnl5Qo9xaS1PFScQ + xrtWZ9eNj2TsIAMp/svJsyGG3OibxfnuAIpSXNQiJPwRlW3irzpGgVx/AoGBANYW + dnhshUcEHMJi3aXwR12OTDnaLoanVGLwLnkqLSYUZA7ZegpKq90UAuBdcEfgdpyi + PhKpeaeIiAaNnFo8m9aoTKr+7I6/uMTlwrVnfrsVTZv3orxjwQV20YIBCVRKD1uX + VhE0ozPZxwwKSPAFocpyWpGHGreGF1AIYBE9UBtjAoGBAI8bfPgJpyFyMiGBjO6z + FwlJc/xlFqDusrcHL7abW5qq0L4v3R+FrJw3ZYufzLTVcKfdj6GelwJJO+8wBm+R + gTKYJItEhT48duLIfTDyIpHGVm9+I1MGhh5zKuCqIhxIYr9jHloBB7kRm0rPvYY4 + VAykcNgyDvtAVODP+4m6JvhjAoGBALbtTqErKN47V0+JJpapLnF0KxGrqeGIjIRV + cYA6V4WYGr7NeIfesecfOC356PyhgPfpcVyEztwlvwTKb3RzIT1TZN8fH4YBr6Ee + KTbTjefRFhVUjQqnucAvfGi29f+9oE3Ei9f7wA+H35ocF6JvTYUsHNMIO/3gZ38N + CPjyCMa9AoGBAMhsITNe3QcbsXAbdUR00dDsIFVROzyFJ2m40i4KCRM35bC/BIBs + q0TY3we+ERB40U8Z2BvU61QuwaunJ2+uGadHo58VSVdggqAo0BSkH58innKKt96J + 69pcVH/4rmLbXdcmNYGm6iu+MlPQk4BUZknHSmVHIFdJ0EPupVaQ8RHT + -----END RSA PRIVATE KEY----- + +SSH Configuration properties + + + + + +Property Name +Remarks + + + + +ignoreLocalSshSettings +If true, use property based SSH config instead of file based. Must be set at as spring.cloud.config.server.git.ignoreLocalSshSettings, not inside a repository definition. + + +privateKey +Valid SSH private key. Must be set if ignoreLocalSshSettings is true and Git URI is SSH format + + +hostKey +Valid SSH host key. Must be set if hostKeyAlgorithm is also set + + +hostKeyAlgorithm +One of ssh-dss, ssh-rsa, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384 ,ecdsa-sha2-nistp521. Must be set if hostKey is also set + + +proxyHost +Hostname for the ssh proxy connection. Is optional and used only when ignoreLocalSshSettings is true + + +proxyPort +Port for the ssh proxy connection. Must be set if proxyHost is also set + + +strictHostKeyChecking +true or false. If false, ignore errors with host key + + +knownHostsFile +Location of custom .known_hosts file + + +preferredAuthentications +Override server authentication method order. This should allow evade login prompts if server has keyboard-interactive authentication before publickey method. + + + +
+
+
+Placeholders in Git Search Paths +Spring Cloud Config Server also supports a search path with +placeholders for the {application} and {profile} (and {label} if +you need it). Example: +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + searchPaths: '{application}' +searches the repository for files in the same name as the directory +(as well as the top level). Wildcards are also valid in a search +path with placeholders (any matching directory is included in the +search). +
+
+Force pull in Git Repositories +As mentioned before Spring Cloud Config Server makes a clone of the +remote git repository and if somehow the local copy gets dirty (e.g. +folder content changes by OS process) so Spring Cloud Config Server +cannot update the local copy from remote repository. +To solve this there is a force-pull property that will make Spring Cloud +Config Server force pull from remote repository if the local copy is dirty. +Example: +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + force-pull: true +If you have a multiple repositories configuration you can configure the +force-pull property per repository. Example: +spring: + cloud: + config: + server: + git: + uri: https://git/common/config-repo.git + force-pull: true + repos: + team-a: + pattern: team-a-* + uri: https://git/team-a/config-repo.git + force-pull: true + team-b: + pattern: team-b-* + uri: https://git/team-b/config-repo.git + force-pull: true + team-c: + pattern: team-c-* + uri: https://git/team-a/config-repo.git + +The default value for force-pull property is false. + +
+
+Deleting untracked branches in Git Repositories +As Spring Cloud Config Server has a clone of the remote git repository +after check-outing branch to local repo (e.g fetching properties by label) it will keep this branch +forever or till the next server restart (which creates new local repo). +So there could be a case when remote branch is deleted but local copy of it is still available for fetching. +And if Spring Cloud Config Server client service starts with --spring.cloud.config.label=deletedRemoteBranch,master +it will fetch properties from deletedRemoteBranch local branch, but not from master. +In order to keep local repository branches clean and up to remote - deleteUntrackedBranches property could be set. +It will make Spring Cloud Config Server force delete untracked branches from local repository. +Example: +spring: + cloud: + config: + server: + git: + uri: https://github.com/spring-cloud-samples/config-repo + deleteUntrackedBranches: true + +The default value for deleteUntrackedBranches property is false. + +
+
+
+Version Control Backend Filesystem Use + +With VCS based backends (git, svn) files are checked out or cloned to the local filesystem. By default they are put in the system temporary directory with a prefix of config-repo-. On linux, for example it could be /tmp/config-repo-<randomid>. Some operating systems routinely clean out temporary directories. This can lead to unexpected behaviour such as missing properties. To avoid this problem, change the directory Config Server uses, by setting spring.cloud.config.server.git.basedir or spring.cloud.config.server.svn.basedir to a directory that does not reside in the system temp structure. + +
+
+File System Backend +There is also a "native" profile in the Config Server that doesn’t use +Git, but just loads the config files from the local classpath or file +system (any static URL you want to point to with +"spring.cloud.config.server.native.searchLocations"). To use the +native profile just launch the Config Server with +"spring.profiles.active=native". + +Remember to use the file: prefix for file resources (the +default without a prefix is usually the classpath). Just as with any +Spring Boot configuration you can embed ${}-style environment +placeholders, but remember that absolute paths in Windows require an +extra "/", e.g. file:///${user.home}/config-repo + + +The default value of the searchLocations is identical to a +local Spring Boot application (so [classpath:/, classpath:/config, +file:./, file:./config]). This does not expose the +application.properties from the server to all clients because any +property sources present in the server are removed before being sent +to the client. + + +A filesystem backend is great for getting started quickly and +for testing. To use it in production you need to be sure that the +file system is reliable, and shared across all instances of the +Config Server. + +The search locations can contain placeholders for {application}, +{profile} and {label}. In this way you can segregate the +directories in the path, and choose a strategy that makes sense for +you (e.g. sub-directory per application, or sub-directory per +profile). +If you don’t use placeholders in the search locations, this repository +also appends the {label} parameter of the HTTP resource to a suffix +on the search path, so properties files are loaded from each search +location and a subdirectory with the same name as the label (the +labelled properties take precedence in the Spring Environment). Thus +the default behaviour with no placeholders is the same as adding a +search location ending with /{label}/. For example file:/tmp/config +is the same as file:/tmp/config,file:/tmp/config/{label}. This behavior can be +disabled by setting spring.cloud.config.server.native.addLabelLocations=false. +
+
+Vault Backend +Spring Cloud Config Server also supports Vault as a backend. + +Vault is a tool for securely accessing secrets. A secret is anything +that you want to tightly control access to, such as API keys, passwords, +certificates, and more. Vault provides a unified interface to any secret, +while providing tight access control and recording a detailed audit log. + +For more information on Vault see the Vault quickstart guide. +To enable the config server to use a Vault backend you can run your config server +with the vault profile. For example in your config server’s application.properties +you can add spring.profiles.active=vault. +By default the config server will assume your Vault server is running at +http://127.0.0.1:8200. It also will assume that the name of backend +is secret and the key is application. All of these defaults can be +configured in your config server’s application.properties. Below is a +table of configurable Vault properties. All properties are prefixed with +spring.cloud.config.server.vault. + + + + + + +Name +Default Value + + + + +host +127.0.0.1 + + +port +8200 + + +scheme +http + + +backend +secret + + +defaultKey +application + + +profileSeparator +, + + + + +All configurable properties can be found in +org.springframework.cloud.config.server.environment.VaultEnvironmentRepository. +With your config server running you can make HTTP requests to the server to retrieve +values from the Vault backend. To do this you will need a token for your Vault server. +First place some data in you Vault. For example +$ vault write secret/application foo=bar baz=bam +$ vault write secret/myapp foo=myappsbar +Now make the HTTP request to your config server to retrieve the values. +$ curl -X "GET" "http://localhost:8888/myapp/default" -H "X-Config-Token: yourtoken" +You should see a response similar to this after making the above request. +{ + "name":"myapp", + "profiles":[ + "default" + ], + "label":null, + "version":null, + "state":null, + "propertySources":[ + { + "name":"vault:myapp", + "source":{ + "foo":"myappsbar" + } + }, + { + "name":"vault:application", + "source":{ + "baz":"bam", + "foo":"bar" + } + } + ] +} +
+Multiple Properties Sources +When using Vault you can provide your applications with multiple properties sources. +For example, assume you have written data to the following paths in Vault. +secret/myApp,dev +secret/myApp +secret/application,dev +secret/application +Properties written to secret/application are available to +all applications using the Config Server. An +application with the name myApp would have any properties +written to secret/myApp and secret/application available to it. +When myApp has the dev profile enabled then properties written to +all of the above paths would be available to it, with properties in +the first path in the list taking priority over the others. +
+
+
+Sharing Configuration With All Applications +
+File Based Repositories +With file-based (i.e. git, svn and native) repositories, resources +with file names in application* are shared between all client +applications (so application.properties, application.yml, +application-*.properties etc.). You can use resources with these +file names to configure global defaults and have them overridden by +application-specific files as necessary. +The #_property_overrides[property overrides] feature can also be used +for setting global defaults, and with placeholders applications are +allowed to override them locally. + +With the "native" profile (local file system backend) it is +recommended that you use an explicit search location that isn’t part +of the server’s own configuration. Otherwise the application* +resources in the default search locations are removed because they are +part of the server. + +
+
+Vault Server +When using Vault as a backend you can share configuration with +all applications by placing configuration in +secret/application. For example, if you run this Vault command +$ vault write secret/application foo=bar baz=bam +All applications using the config server will have the properties +foo and baz available to them. +
+
+
+JDBC Backend +Spring Cloud Config Server supports JDBC (relation database) as a +backend for configuration properties. You can enable this feature by +adding spring-jdbc to the classpath, and using the "jdbc" profile, +or by adding a bean of type JdbcEnvironmentRepository. Spring Boot +will configure a data source if you include the right dependencies on +the classpath (see the user guide for more details on that). +The database needs to have a table called "PROPERTIES" with columns +"APPLICATION", "PROFILE", "LABEL" (with the usual Environment +meaning), plus "KEY" and "VALUE" for the key and value pairs in +Properties style. All fields are of type String in Java, so you can +make them VARCHAR of whatever length you need. Property values +behave in the same way as they would if they came from Spring Boot +properties files named {application}-{profile}.properties, including +all the encryption and decryption, which will be applied as +post-processing steps (i.e. not in the repository implementation +directly). +
+
+Composite Environment Repositories +In some scenarios you may wish to pull configuration data from multiple +environment repositories. To do this you can just enable +multiple profiles in your config server’s application properties or YAML file. +If, for example, you want to pull configuration data from a Git repository +as well as a SVN repository you would set the following properties for your +configuration server. +spring: + profiles: + active: git, svn + cloud: + config: + server: + svn: + uri: file:///path/to/svn/repo + order: 2 + git: + uri: file:///path/to/git/repo + order: 1 +In addition to each repo specifying a URI, you can also specify an order property. +The order property allows you to specify the priority order for all your repositories. +The lower the numerical value of the order property the higher priority it will have. +The priority order of a repository will help resolve any potential conflicts between +repositories that contain values for the same properties. + +Any type of failure when retrieving values from an environment repositoy +will result in a failure for the entire composite environment. + + +When using a composite environment it is important that all repos contain +the same label(s). If you have an environment similar to the one above and you request +configuration data with the label master but the SVN +repo does not contain a branch called master the entire request will fail. + +
+Custom Composite Environment Repositories +It is also possible to provide your own EnvironmentRepository bean +to be included as part of a composite environment in addition to +using one of the environment repositories from Spring Cloud. To do this your bean +must implement the EnvironmentRepository interface. If you would like to control +the priority of you custom EnvironmentRepository within the composite +environment you should also implement the Ordered interface and override the +getOrdered method. If you do not implement the Ordered interface then your +EnvironmentRepository will be given the lowest priority. +
+
+
+Property Overrides +The Config Server has an "overrides" feature that allows the operator +to provide configuration properties to all applications that cannot be +accidentally changed by the application using the normal Spring Boot +hooks. To declare overrides just add a map of name-value pairs to +spring.cloud.config.server.overrides. For example +spring: + cloud: + config: + server: + overrides: + foo: bar +will cause all applications that are config clients to read foo=bar +independent of their own configuration. (Of course an application can +use the data in the Config Server in any way it likes, so overrides +are not enforceable, but they do provide useful default behaviour if +they are Spring Cloud Config clients.) + +Normal, Spring environment placeholders with "${}" can be escaped +(and resolved on the client) by using backslash ("\") to escape the +"$" or the "{", e.g. \${app.foo:bar} resolves to "bar" unless the +app provides its own "app.foo". Note that in YAML you don’t need to +escape the backslash itself, but in properties files you do, when you +configure the overrides on the server. + +You can change the priority of all overrides in the client to be more +like default values, allowing applications to supply their own values +in environment variables or System properties, by setting the flag +spring.cloud.config.overrideNone=true (default is false) in the +remote repository. +
+
+
+Health Indicator +Config Server comes with a Health Indicator that checks if the configured +EnvironmentRepository is working. By default it asks the EnvironmentRepository +for an application named app, the default profile and the default +label provided by the EnvironmentRepository implementation. +You can configure the Health Indicator to check more applications +along with custom profiles and custom labels, e.g. +spring: + cloud: + config: + server: + health: + repositories: + myservice: + label: mylabel + myservice-dev: + name: myservice + profiles: development +You can disable the Health Indicator by setting spring.cloud.config.server.health.enabled=false. +
+
+Security +You are free to secure your Config Server in any way that makes sense +to you (from physical network security to OAuth2 bearer +tokens), and Spring Security and Spring Boot make it easy to do pretty +much anything. +To use the default Spring Boot configured HTTP Basic security, just +include Spring Security on the classpath (e.g. through +spring-boot-starter-security). The default is a username of "user" +and a randomly generated password, which isn’t going to be very useful +in practice, so we recommend you configure the password (via +security.user.password) and encrypt it (see below for instructions +on how to do that). +
+
+Encryption and Decryption + +Prerequisites: to use the encryption and decryption features +you need the full-strength JCE installed in your JVM (it’s not there by default). +You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" +from Oracle, and follow instructions for installation (essentially replace the 2 policy files +in the JRE lib/security directory with the ones that you downloaded). + +If the remote property sources contain encrypted content (values +starting with {cipher}) they will be decrypted before sending to +clients over HTTP. The main advantage of this set up is that the +property values don’t have to be in plain text when they are "at rest" +(e.g. in a git repository). If a value cannot be decrypted it is +removed from the property source and an additional property is added +with the same key, but prefixed with "invalid." and a value that means +"not applicable" (usually "<n/a>"). This is largely to prevent cipher +text being used as a password and accidentally leaking. +If you are setting up a remote config repository for config client +applications it might contain an application.yml like this, for +instance: + +application.yml + +spring: + datasource: + username: dbuser + password: '{cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ' + + +Encrypted values in a .properties file must not be wrapped in quotes, otherwise the value will not be decrypted: + +application.properties + +spring.datasource.username: dbuser +spring.datasource.password: {cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ + + +You can safely push this plain text to a shared git repository and the +secret password is protected. +The server also exposes /encrypt and /decrypt endpoints (on the +assumption that these will be secured and only accessed by authorized +agents). If you are editing a remote config file you can use the Config Server +to encrypt values by POSTing to the /encrypt endpoint, e.g. +$ curl localhost:8888/encrypt -d mysecret +682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda + +If the value you are encrypting has characters in it that need to be URL encoded you should use +the --data-urlencode option to curl to make sure they are encoded properly. + + +Be sure not to include any of the curl command statistics in the encrypted value. +Outputting the value to a file can help avoid this problem. + +The inverse operation is also available via /decrypt (provided the server is +configured with a symmetric key or a full key pair): +$ curl localhost:8888/decrypt -d 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda +mysecret + +If you are testing like this with curl, then use +--data-urlencode (instead of -d) or set an explicit Content-Type: +text/plain to make sure curl encodes the data correctly when there +are special characters ('+' is particularly tricky). + +Take the encrypted value and add the {cipher} prefix before you put +it in the YAML or properties file, and before you commit and push it +to a remote, potentially insecure store. +The /encrypt and /decrypt endpoints also both accept paths of the +form /*/{name}/{profiles} which can be used to control cryptography +per application (name) and profile when clients call into the main +Environment resource. + +to control the cryptography in this granular way you must also +provide a @Bean of type TextEncryptorLocator that creates a +different encryptor per name and profiles. The one that is provided +by default does not do this (so all encryptions use the same key). + +The spring command line client (with Spring Cloud CLI extensions +installed) can also be used to encrypt and decrypt, e.g. +$ spring encrypt mysecret --key foo +682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda +$ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda +mysecret +To use a key in a file (e.g. an RSA public key for encryption) prepend +the key value with "@" and provide the file path, e.g. +$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub +AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+... +The key argument is mandatory (despite having a -- prefix). +
+
+Key Management +The Config Server can use a symmetric (shared) key or an asymmetric +one (RSA key pair). The asymmetric choice is superior in terms of +security, but it is often more convenient to use a symmetric key since +it is just a single property value to configure in the bootstrap.properties. +To configure a symmetric key you just need to set encrypt.key to a +secret String (or use an enviroment variable ENCRYPT_KEY to keep it +out of plain text configuration files). + +You cannot configure an asymmetric key using encrypt.key. + +To configure an asymmetric key use a keystore (e.g. as +created by the keytool utility that comes with the JDK). The +keystore properties are encrypt.keyStore.* with * equal to + + +location (a Resource location), + + +password (to unlock the keystore) and + + +alias (to identify which key in the store is to be +used). + + +The encryption is done with the public key, and a private key is +needed for decryption. Thus in principle you can configure only the +public key in the server if you only want to do encryption (and are +prepared to decrypt the values yourself locally with the private +key). In practice you might not want to do that because it spreads the +key management process around all the clients, instead of +concentrating it in the server. On the other hand it’s a useful option +if your config server really is relatively insecure and only a +handful of clients need the encrypted properties. +
+
+Creating a Key Store for Testing +To create a keystore for testing you can do something like this: +$ keytool -genkeypair -alias mytestkey -keyalg RSA \ + -dname "CN=Web Server,OU=Unit,O=Organization,L=City,S=State,C=US" \ + -keypass changeme -keystore server.jks -storepass letmein +Put the server.jks file in the classpath (for instance) and then in +your bootstrap.yml for the Config Server: +encrypt: + keyStore: + location: classpath:/server.jks + password: letmein + alias: mytestkey + secret: changeme +
+
+Using Multiple Keys and Key Rotation +In addition to the {cipher} prefix in encrypted property values, the +Config Server looks for {name:value} prefixes (zero or many) before +the start of the (Base64 encoded) cipher text. The keys are passed to +a TextEncryptorLocator which can do whatever logic it needs to +locate a TextEncryptor for the cipher. If you have configured a +keystore (encrypt.keystore.location) the default locator will look +for keys in the store with aliases as supplied by the "key" prefix, +i.e. with a cipher text like this: +foo: + bar: `{cipher}{key:testkey}...` +the locator will look for a key named "testkey". A secret can also be +supplied via a {secret:…​} value in the prefix, but if it is not +the default is to use the keystore password (which is what you get +when you build a keytore and don’t specify a secret). If you do +supply a secret it is recommended that you also encrypt the secrets +using a custom SecretLocator. +Key rotation is hardly ever necessary on cryptographic grounds if the +keys are only being used to encrypt a few bytes of configuration data +(i.e. they are not being used elsewhere), but occasionally you might +need to change the keys if there is a security breach for instance. In +that case all the clients would need to change their source config +files (e.g. in git) and use a new {key:…​} prefix in all the +ciphers, checking beforehand of course that the key alias is available +in the Config Server keystore. + +the {name:value} prefixes can also be added to plaintext posted +to the /encrypt endpoint, if you want to let the Config Server +handle all encryption as well as decryption. + +
+
+Serving Encrypted Properties +Sometimes you want the clients to decrypt the configuration locally, +instead of doing it in the server. In that case you can still have +/encrypt and /decrypt endpoints (if you provide the encrypt.* +configuration to locate a key), but you need to explicitly switch off +the decryption of outgoing properties by placing +spring.cloud.config.server.encrypt.enabled=false in bootstrap.[yml|properties]. +If you don’t care about the endpoints, then it should work if you configure neither the +key nor the enabled flag. +
+ + +Serving Alternative Formats +The default JSON format from the environment endpoints is perfect for +consumption by Spring applications because it maps directly onto the +Environment abstraction. If you prefer you can consume the same data +as YAML or Java properties by adding a suffix to the resource path +(".yml", ".yaml" or ".properties"). This can be useful for consumption +by applications that do not care about the structure of the JSON +endpoints, or the extra metadata they provide, for example an +application that is not using Spring might benefit from the simplicity +of this approach. +The YAML and properties representations have an additional flag +(provided as a boolean query parameter resolvePlaceholders) to +signal that placeholders in the source documents, in the standard +Spring ${…​} form, should be resolved in the output where possible +before rendering. This is a useful feature for consumers that don’t +know about the Spring placeholder conventions. + +there are limitations in using the YAML or properties formats, +mainly in relation to the loss of metadata. The JSON is structured as +an ordered list of property sources, for example, with names that +correlate with the source. The YAML and properties forms are coalesced +into a single map, even if the origin of the values has multiple +sources, and the names of the original source files are lost. The YAML +representation is not necessarily a faithful representation of the +YAML source in a backing repository either: it is constructed from a +list of flat property sources, and assumptions have to be made about +the form of the keys. + + + +Serving Plain Text +Instead of using the Environment abstraction (or one of the +alternative representations of it in YAML or properties format) your +applications might need generic plain text configuration files, +tailored to their environment. The Config Server provides these +through an additional endpoint at /{name}/{profile}/{label}/{path} +where "name", "profile" and "label" have the same meaning as the +regular environment endpoint, but "path" is a file name +(e.g. log.xml). The source files for this endpoint are located in +the same way as for the environment endpoints: the same search path is +used as for properties or YAML files, but instead of aggregating all +matching resources, only the first one to match is returned. +After a resource is located, placeholders in the normal format +(${…​}) are resolved using the effective Environment for the +application name, profile and label supplied. In this way the resource +endpoint is tightly integrated with the environment +endpoints. Example, if you have this layout for a GIT (or SVN) +repository: +application.yml +nginx.conf +where nginx.conf looks like this: +server { + listen 80; + server_name ${nginx.server.name}; +} +and application.yml like this: +nginx: + server: + name: example.com +--- +spring: + profiles: development +nginx: + server: + name: develop.com +then the /foo/default/master/nginx.conf resource looks like this: +server { + listen 80; + server_name example.com; +} +and /foo/development/master/nginx.conf like this: +server { + listen 80; + server_name develop.com; +} + +Just like the source files for environment configuration, the +"profile" is used to resolve the file name, so if you want a +profile-specific file then /*/development/*/logback.xml will be +resolved by a file called logback-development.xml (in preference +to logback.xml). + + +If you do not want to supply the label and let the server use the default label, you can supply a useDefaultLabel request parameter. So, the above example for the default profile could look like /foo/default/nginx.conf?useDefaultLabel. + + + +Embedding the Config Server +The Config Server runs best as a standalone application, but if you +need to you can embed it in another application. Just use the +@EnableConfigServer annotation. An optional property that can be +useful in this case is spring.cloud.config.server.bootstrap which is +a flag to indicate that the server should configure itself from its +own remote repository. The flag is off by default because it can delay +startup, but when embedded in another application it makes sense to +initialize the same way as any other application. + +It should be obvious, but remember that if you use the bootstrap +flag the config server will need to have its name and repository URI +configured in bootstrap.yml. + +To change the location of the server endpoints you can (optionally) +set spring.cloud.config.server.prefix, e.g. "/config", to serve the +resources under a prefix. The prefix should start but not end with a +"/". It is applied to the @RequestMappings in the Config Server +(i.e. underneath the Spring Boot prefixes server.servletPath and +server.contextPath). +If you want to read the configuration for an application directly from +the backend repository (instead of from the config server) that’s +basically an embedded config server with no endpoints. You can switch +off the endpoints entirely if you don’t use the @EnableConfigServer +annotation (just set spring.cloud.config.server.bootstrap=true). + + +Push Notifications and Spring Cloud Bus +Many source code repository providers (like Github, Gitlab or Bitbucket +for instance) will notify you of changes in a repository through a +webhook. You can configure the webhook via the provider’s user +interface as a URL and a set of events in which you are +interested. For instance +Github +will POST to the webhook with a JSON body containing a list of +commits, and a header "X-Github-Event" equal to "push". If you add a +dependency on the spring-cloud-config-monitor library and activate +the Spring Cloud Bus in your Config Server, then a "/monitor" endpoint +is enabled. +When the webhook is activated the Config Server will send a +RefreshRemoteApplicationEvent targeted at the applications it thinks +might have changed. The change detection can be strategized, but by +default it just looks for changes in files that match the application +name (e.g. "foo.properties" is targeted at the "foo" application, and +"application.properties" is targeted at all applications). The strategy +if you want to override the behaviour is PropertyPathNotificationExtractor +which accepts the request headers and body as parameters and returns a list +of file paths that changed. +The default configuration works out of the box with Github, Gitlab or +Bitbucket. In addition to the JSON notifications from Github, Gitlab +or Bitbucket you can trigger a change notification by POSTing to +"/monitor" with a form-encoded body parameters path={name}. This will +broadcast to applications matching the "{name}" pattern (can contain +wildcards). + +the RefreshRemoteApplicationEvent will only be transmitted if +the spring-cloud-bus is activated in the Config Server and in the +client application. + + +the default configuration also detects filesystem changes in +local git repositories (the webhook is not used in that case but as +soon as you edit a config file a refresh will be broadcast). + + + +Spring Cloud Config Client +A Spring Boot application can take immediate advantage of the Spring +Config Server (or other external property sources provided by the +application developer), and it will also pick up some additional +useful features related to Environment change events. +
+Config First Bootstrap +This is the default behaviour for any application which has the Spring +Cloud Config Client on the classpath. When a config client starts up +it binds to the Config Server (via the bootstrap configuration +property spring.cloud.config.uri) and initializes Spring +Environment with remote property sources. +The net result of this is that all client apps that want to consume +the Config Server need a bootstrap.yml (or an environment variable) +with the server address in spring.cloud.config.uri (defaults to +"http://localhost:8888"). +
+
+Discovery First Bootstrap +If you are using a `DiscoveryClient implementation, such as Spring Cloud Netflix +and Eureka Service Discovery or Spring Cloud Consul (Spring Cloud Zookeeper does +not support this yet), then you can have the Config Server register with the +Discovery Service if you want to, but in the default "Config First" mode, +clients won’t be able to take advantage of the registration. +If you prefer to use DiscoveryClient to locate the Config Server, you can do +that by setting spring.cloud.config.discovery.enabled=true (default +"false"). The net result of that is that client apps all need a +bootstrap.yml (or an environment variable) with the appropriate discovery +configuration. For example, with Spring Cloud Netflix, you need to define the +Eureka server address, e.g. in eureka.client.serviceUrl.defaultZone. The +price for using this option is an extra network round trip on start up to +locate the service registration. The benefit is that the Config Server +can change its co-ordinates, as long as the Discovery Service is a fixed point. The +default service id is "configserver" but you can change that on the +client with spring.cloud.config.discovery.serviceId (and on the server +in the usual way for a service, e.g. by setting spring.application.name). +The discovery client implementations all support some kind of metadata +map (e.g. for Eureka we have eureka.instance.metadataMap). Some +additional properties of the Config Server may need to be configured +in its service registration metadata so that clients can connect +correctly. If the Config Server is secured with HTTP Basic you can +configure the credentials as "username" and "password". And if the +Config Server has a context path you can set "configPath". Example, +for a Config Server that is a Eureka client: + +bootstrap.yml + +eureka: + instance: + ... + metadataMap: + user: osufhalskjrtl + password: lviuhlszvaorhvlo5847 + configPath: /config + + +
+
+Config Client Fail Fast +In some cases, it may be desirable to fail startup of a service if +it cannot connect to the Config Server. If this is the desired +behavior, set the bootstrap configuration property +spring.cloud.config.failFast=true and the client will halt with +an Exception. +
+
+Config Client Retry +If you expect that the config server may occasionally be unavailable when +your app starts, you can ask it to keep trying after a failure. First you need +to set spring.cloud.config.failFast=true, and then you need to add +spring-retry and spring-boot-starter-aop to your classpath. The default +behaviour is to retry 6 times with an initial backoff interval of 1000ms and an +exponential multiplier of 1.1 for subsequent backoffs. You can configure these +properties (and others) using spring.cloud.config.retry.* configuration properties. + +To take full control of the retry add a @Bean of type +RetryOperationsInterceptor with id "configServerRetryInterceptor". Spring +Retry has a RetryInterceptorBuilder that makes it easy to create one. + +
+
+Locating Remote Configuration Resources +The Config Service serves property sources from /{name}/{profile}/{label}, where the default bindings in the client app are + + +"name" = ${spring.application.name} + + +"profile" = ${spring.profiles.active} (actually Environment.getActiveProfiles()) + + +"label" = "master" + + +All of them can be overridden by setting spring.cloud.config.* +(where * is "name", "profile" or "label"). The "label" is useful for +rolling back to previous versions of configuration; with the default +Config Server implementation it can be a git label, branch name or +commit id. Label can also be provided as a comma-separated list, in +which case the items in the list are tried on-by-one until one succeeds. +This can be useful when working on a feature branch, for instance, +when you might want to align the config label with your branch, but +make it optional (e.g. spring.cloud.config.label=myfeature,develop). +
+
+Security +If you use HTTP Basic security on the server then clients just need to +know the password (and username if it isn’t the default). You can do +that via the config server URI, or via separate username and password +properties, e.g. + +bootstrap.yml + +spring: + cloud: + config: + uri: https://user:secret@myconfig.mycompany.com + + +or + +bootstrap.yml + +spring: + cloud: + config: + uri: https://myconfig.mycompany.com + username: user + password: secret + + +The spring.cloud.config.password and spring.cloud.config.username +values override anything that is provided in the URI. +If you deploy your apps on Cloud Foundry then the best way to provide +the password is through service credentials, e.g. in the URI, since +then it doesn’t even need to be in a config file. An example which +works locally and for a user-provided service on Cloud Foundry named +"configserver": + +bootstrap.yml + +spring: + cloud: + config: + uri: ${vcap.services.configserver.credentials.uri:http://user:password@localhost:8888} + + +If you use another form of security you might need to provide a +RestTemplate to the ConfigServicePropertySourceLocator (e.g. by +grabbing it in the bootstrap context and injecting one). +
+Health Indicator +The Config Client supplies a Spring Boot Health Indicator that attempts to load configuration from Config Server. The health indicator can be disabled by setting health.config.enabled=false. The response is also cached for performance reasons. The default cache time to live is 5 minutes. To change that value set the health.config.time-to-live property (in milliseconds). +
+
+Providing A Custom RestTemplate +In some cases you might need to customize the requests made to the config server from +the client. Typically this involves passing special Authorization headers to +authenticate requests to the server. To provide a custom RestTemplate follow the +steps below. + + +Create a new configuration bean with an implementation of PropertySourceLocator. + + + +CustomConfigServiceBootstrapConfiguration.java + +@Configuration +public class CustomConfigServiceBootstrapConfiguration { + @Bean + public ConfigServicePropertySourceLocator configServicePropertySourceLocator() { + ConfigClientProperties clientProperties = configClientProperties(); + ConfigServicePropertySourceLocator configServicePropertySourceLocator = new ConfigServicePropertySourceLocator(clientProperties); + configServicePropertySourceLocator.setRestTemplate(customRestTemplate(clientProperties)); + return configServicePropertySourceLocator; + } +} + + + + +In resources/META-INF create a file called +spring.factories and specify your custom configuration. + + + +spring.factories + +org.springframework.cloud.bootstrap.BootstrapConfiguration = com.my.config.client.CustomConfigServiceBootstrapConfiguration + + +
+
+Vault +When using Vault as a backend to your config server the client will need to +supply a token for the server to retrieve values from Vault. This token +can be provided within the client by setting spring.cloud.config.token +in bootstrap.yml. + +bootstrap.yml + +spring: + cloud: + config: + token: YourVaultToken + + +
+
+
+Vault +
+Nested Keys In Vault +Vault supports the ability to nest keys in a value stored in Vault. For example +echo -n '{"appA": {"secret": "appAsecret"}, "bar": "baz"}' | vault write secret/myapp - +This command will write a JSON object to your Vault. To access these values in Spring +you would use the traditional dot(.) annotation. For example +@Value("${appA.secret}") +String name = "World"; +The above code would set the name variable to appAsecret. +
+
+ + + +Spring Cloud Netflix + +1.3.8.RELEASE +This project provides Netflix OSS integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with battle-tested Netflix components. The +patterns provided include Service Discovery (Eureka), Circuit Breaker (Hystrix), +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon). + + +Service Discovery: Eureka Clients +Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Eureka is the Netflix Service Discovery Server and Client. The server can be configured and deployed to be highly available, with each server replicating state about the registered services to the others. +
+How to Include Eureka Client +To include Eureka Client in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-eureka-client. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +
+
+Registering with Eureka +When a client registers with Eureka, it provides meta-data about itself +such as host and port, health indicator URL, home page etc. Eureka +receives heartbeat messages from each instance belonging to a service. +If the heartbeat fails over a configurable timetable, the instance is +normally removed from the registry. +Example eureka client: +@Configuration +@ComponentScan +@EnableAutoConfiguration +@RestController +public class Application { + + @RequestMapping("/") + public String home() { + return "Hello world"; + } + + public static void main(String[] args) { + new SpringApplicationBuilder(Application.class).web(true).run(args); + } + +} +(i.e. utterly normal Spring Boot app). By having spring-cloud-starter-netflix-eureka-client + on the classpath your application will automatically register with the Eureka Server. Configuration is required to +locate the Eureka server. Example: + +application.yml + +eureka: + client: + serviceUrl: + defaultZone: http://localhost:8761/eureka/ + + +where "defaultZone" is a magic string fallback value that provides the +service URL for any client that doesn’t express a preference +(i.e. it’s a useful default). +The default application name (service ID), virtual host and non-secure +port, taken from the Environment, are ${spring.application.name}, +${spring.application.name} and ${server.port} respectively. +Having spring-cloud-starter-netflix-eureka-client on the classpath +makes the app into both a Eureka "instance" +(i.e. it registers itself) and a "client" (i.e. it can query the +registry to locate other services). The instance behaviour is driven +by eureka.instance.* configuration keys, but the defaults will be +fine if you ensure that your application has a +spring.application.name (this is the default for the Eureka service +ID, or VIP). +See EurekaInstanceConfigBean and EurekaClientConfigBean for more details of the configurable options. +To disable the Eureka Discovery Client you can set eureka.client.enabled to false. +
+
+Authenticating with the Eureka Server +HTTP basic authentication will be automatically added to your eureka +client if one of the eureka.client.serviceUrl.defaultZone URLs has +credentials embedded in it (curl style, like +http://user:password@localhost:8761/eureka). For more complex needs +you can create a @Bean of type DiscoveryClientOptionalArgs and +inject ClientFilter instances into it, all of which will be applied +to the calls from the client to the server. + +Because of a limitation in Eureka it isn’t possible to support +per-server basic auth credentials, so only the first set that are +found will be used. + +
+
+Status Page and Health Indicator +The status page and health indicators for a Eureka instance default to +"/info" and "/health" respectively, which are the default locations of +useful endpoints in a Spring Boot Actuator application. You need to +change these, even for an Actuator application if you use a +non-default context path or servlet path +(e.g. server.servletPath=/foo) Example: + +application.yml + +eureka: + instance: + statusPageUrlPath: ${server.servletPath}/info + healthCheckUrlPath: ${server.servletPath}/health + + +These links show up in the metadata that is consumed by clients, and +used in some scenarios to decide whether to send requests to your +application, so it’s helpful if they are accurate. + +In Dalston it was also required to set the status and health check URLs when changing +that management context path. This requirement was removed beinging in Edgware. + +
+
+Registering a Secure Application +If your app wants to be contacted over HTTPS you can set two flags in +the EurekaInstanceConfig, viz +eureka.instance.[nonSecurePortEnabled,securePortEnabled]=[false,true] +respectively. This will make Eureka publish instance information +showing an explicit preference for secure communication. The Spring +Cloud DiscoveryClient will always return a URI starting with https for a +service configured this way, and the Eureka (native) instance +information will have a secure health check URL. +Because of the way +Eureka works internally, it will still publish a non-secure URL for +status and home page unless you also override those explicitly. +You can use placeholders to configure the eureka instance urls, +e.g. + +application.yml + +eureka: + instance: + statusPageUrl: https://${eureka.hostname}/info + healthCheckUrl: https://${eureka.hostname}/health + homePageUrl: https://${eureka.hostname}/ + + +(Note that ${eureka.hostname} is a native placeholder only available +in later versions of Eureka. You could achieve the same thing with +Spring placeholders as well, e.g. using ${eureka.instance.hostName}.) + +If your app is running behind a proxy, and the SSL termination +is in the proxy (e.g. if you run in Cloud Foundry or other platforms +as a service) then you will need to ensure that the proxy "forwarded" +headers are intercepted and handled by the application. An embedded +Tomcat container in a Spring Boot app does this automatically if it +has explicit configuration for the 'X-Forwarded-\*` headers. A sign +that you got this wrong will be that the links rendered by your app to +itself will be wrong (the wrong host, port or protocol). + +
+
+Eureka’s Health Checks +By default, Eureka uses the client heartbeat to determine if a client is up. +Unless specified otherwise the Discovery Client will not propagate the +current health check status of the application per the Spring Boot Actuator. Which means +that after successful registration Eureka will always announce that the +application is in 'UP' state. This behaviour can be altered by enabling +Eureka health checks, which results in propagating application status +to Eureka. As a consequence every other application won’t be sending +traffic to application in state other then 'UP'. + +application.yml + +eureka: + client: + healthcheck: + enabled: true + + + +eureka.client.healthcheck.enabled=true should only be set in application.yml. Setting the value in bootstrap.yml will cause undesirable side effects like registering in eureka with an UNKNOWN status. + +If you require more control over the health checks, you may consider +implementing your own com.netflix.appinfo.HealthCheckHandler. +
+
+Eureka Metadata for Instances and Clients +It’s worth spending a bit of time understanding how the Eureka metadata works, so you can use it in a way that makes sense in your platform. There is standard metadata for things like hostname, IP address, port numbers, status page and health check. These are published in the service registry and used by clients to contact the services in a straightforward way. Additional metadata can be added to the instance registration in the eureka.instance.metadataMap, and this will be accessible in the remote clients, but in general will not change the behaviour of the client, unless it is made aware of the meaning of the metadata. There are a couple of special cases described below where Spring Cloud already assigns meaning to the metadata map. +
+Using Eureka on Cloud Foundry +Cloud Foundry has a global router so that all instances of the same app have the same hostname (it’s the same in other PaaS solutions with a similar architecture). This isn’t necessarily a barrier to using Eureka, but if you use the router (recommended, or even mandatory depending on the way your platform was set up), you need to explicitly set the hostname and port numbers (secure or non-secure) so that they use the router. You might also want to use instance metadata so you can distinguish between the instances on the client (e.g. in a custom load balancer). By default, the eureka.instance.instanceId is vcap.application.instance_id. For example: + +application.yml + +eureka: + instance: + hostname: ${vcap.application.uris[0]} + nonSecurePort: 80 + + +Depending on the way the security rules are set up in your Cloud Foundry instance, you might be able to register and use the IP address of the host VM for direct service-to-service calls. This feature is not (yet) available on Pivotal Web Services (PWS). +
+
+Using Eureka on AWS +If the application is planned to be deployed to an AWS cloud, then the Eureka instance will have to be configured to be AWS aware and this can be done by customizing the EurekaInstanceConfigBean the following way: +@Bean +@Profile("!default") +public EurekaInstanceConfigBean eurekaInstanceConfig(InetUtils inetUtils) { + EurekaInstanceConfigBean b = new EurekaInstanceConfigBean(inetUtils); + AmazonInfo info = AmazonInfo.Builder.newBuilder().autoBuild("eureka"); + b.setDataCenterInfo(info); + return b; +} +
+
+Changing the Eureka Instance ID +A vanilla Netflix Eureka instance is registered with an ID that is equal to its host name (i.e. only one service per host). Spring Cloud Eureka provides a sensible default that looks like this: ${spring.cloud.client.hostname}:${spring.application.name}:${spring.application.instance_id:${server.port}}}. For example myhost:myappname:8080. +Using Spring Cloud you can override this by providing a unique identifier in eureka.instance.instanceId. For example: + +application.yml + +eureka: + instance: + instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}} + + +With this metadata, and multiple service instances deployed on +localhost, the random value will kick in there to make the instance +unique. In Cloud Foundry the vcap.application.instance_id will be +populated automatically in a Spring Boot application, so the +random value will not be needed. +
+
+
+Using the EurekaClient +Once you have an app that is a discovery client you can use it to +discover service instances from the Eureka Server. One way to do that is to use the native +com.netflix.discovery.EurekaClient (as opposed to the Spring +Cloud DiscoveryClient), e.g. +@Autowired +private EurekaClient discoveryClient; + +public String serviceUrl() { + InstanceInfo instance = discoveryClient.getNextServerFromEureka("STORES", false); + return instance.getHomePageUrl(); +} + +Don’t use the EurekaClient in @PostConstruct method or in a +@Scheduled method (or anywhere where the ApplicationContext might +not be started yet). It is initialized in a SmartLifecycle (with +phase=0) so the earliest you can rely on it being available is in +another SmartLifecycle with higher phase. + +
+EurekaClient without Jersey +By default, EurekaClient uses Jersey for HTTP communication. If you wish +to avoid dependencies from Jersey, you can exclude it from your dependencies. +Spring Cloud will auto configure a transport client based on Spring +RestTemplate. +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-eureka</artifactId> + <exclusions> + <exclusion> + <groupId>com.sun.jersey</groupId> + <artifactId>jersey-client</artifactId> + </exclusion> + <exclusion> + <groupId>com.sun.jersey</groupId> + <artifactId>jersey-core</artifactId> + </exclusion> + <exclusion> + <groupId>com.sun.jersey.contribs</groupId> + <artifactId>jersey-apache-client4</artifactId> + </exclusion> + </exclusions> +</dependency> +
+
+
+Alternatives to the native Netflix EurekaClient +You don’t have to use the raw Netflix EurekaClient and usually it +is more convenient to use it behind a wrapper of some sort. Spring +Cloud has support for Feign (a REST client +builder) and also Spring RestTemplate using +the logical Eureka service identifiers (VIPs) instead of physical +URLs. To configure Ribbon with a fixed list of physical servers you +can simply set <client>.ribbon.listOfServers to a comma-separated +list of physical addresses (or hostnames), where <client> is the ID +of the client. +You can also use the org.springframework.cloud.client.discovery.DiscoveryClient +which provides a simple API for discovery clients that is not specific +to Netflix, e.g. +@Autowired +private DiscoveryClient discoveryClient; + +public String serviceUrl() { + List<ServiceInstance> list = discoveryClient.getInstances("STORES"); + if (list != null && list.size() > 0 ) { + return list.get(0).getUri(); + } + return null; +} +
+
+Why is it so Slow to Register a Service? +Being an instance also involves a periodic heartbeat to the registry +(via the client’s serviceUrl) with default duration 30 seconds. A +service is not available for discovery by clients until the instance, +the server and the client all have the same metadata in their local +cache (so it could take 3 heartbeats). You can change the period using +eureka.instance.leaseRenewalIntervalInSeconds and this will speed up +the process of getting clients connected to other services. In +production it’s probably better to stick with the default because +there are some computations internally in the server that make +assumptions about the lease renewal period. +
+
+Zones +If you have deployed Eureka clients to multiple zones than you may prefer that +those clients leverage services within the same zone before trying services +in another zone. To do this you need to configure your Eureka clients correctly. +First, you need to make sure you have Eureka servers deployed to each zone and that +they are peers of each other. See the section on zones and regions +for more information. +Next you need to tell Eureka which zone your service is in. You can do this using +the metadataMap property. For example if service 1 is deployed to both zone 1 +and zone 2 you would need to set the following Eureka properties in service 1 +Service 1 in Zone 1 +eureka.instance.metadataMap.zone = zone1 +eureka.client.preferSameZoneEureka = true +Service 1 in Zone 2 +eureka.instance.metadataMap.zone = zone2 +eureka.client.preferSameZoneEureka = true +
+ + +Service Discovery: Eureka Server +
+How to Include Eureka Server +To include Eureka Server in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-eureka-server. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +
+
+How to Run a Eureka Server +Example eureka server; +@SpringBootApplication +@EnableEurekaServer +public class Application { + + public static void main(String[] args) { + new SpringApplicationBuilder(Application.class).web(true).run(args); + } + +} +The server has a home page with a UI, and HTTP API endpoints per the +normal Eureka functionality under /eureka/*. +Eureka background reading: see flux capacitor and google group discussion. + +Due to Gradle’s dependency resolution rules and the lack of a parent bom feature, simply depending on spring-cloud-starter-netflix-eureka-server can cause failures on application startup. To remedy this the Spring Boot Gradle plugin must be added and the Spring cloud starter parent bom must be imported like so: + +build.gradle + +buildscript { + dependencies { + classpath("org.springframework.boot:spring-boot-gradle-plugin:1.5.10.RELEASE") + } +} + +apply plugin: "spring-boot" + +dependencyManagement { + imports { + mavenBom "org.springframework.cloud:spring-cloud-dependencies:Edgware.SR2" + } +} + + + +
+
+High Availability, Zones and Regions +The Eureka server does not have a backend store, but the service +instances in the registry all have to send heartbeats to keep their +registrations up to date (so this can be done in memory). Clients also +have an in-memory cache of eureka registrations (so they don’t have to +go to the registry for every single request to a service). +By default every Eureka server is also a Eureka client and requires +(at least one) service URL to locate a peer. If you don’t provide it +the service will run and work, but it will shower your logs with a lot +of noise about not being able to register with the peer. +See also below for details of Ribbon +support on the client side for Zones and Regions. +
+
+Standalone Mode +The combination of the two caches (client and server) and the +heartbeats make a standalone Eureka server fairly resilient to +failure, as long as there is some sort of monitor or elastic runtime +keeping it alive (e.g. Cloud Foundry). In standalone mode, you might +prefer to switch off the client side behaviour, so it doesn’t keep +trying and failing to reach its peers. Example: + +application.yml (Standalone Eureka Server) + +server: + port: 8761 + +eureka: + instance: + hostname: localhost + client: + registerWithEureka: false + fetchRegistry: false + serviceUrl: + defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/ + + +Notice that the serviceUrl is pointing to the same host as the local +instance. +
+
+Peer Awareness +Eureka can be made even more resilient and available by running +multiple instances and asking them to register with each other. In +fact, this is the default behaviour, so all you need to do to make it +work is add a valid serviceUrl to a peer, e.g. + +application.yml (Two Peer Aware Eureka Servers) + +--- +spring: + profiles: peer1 +eureka: + instance: + hostname: peer1 + client: + serviceUrl: + defaultZone: http://peer2/eureka/ + +--- +spring: + profiles: peer2 +eureka: + instance: + hostname: peer2 + client: + serviceUrl: + defaultZone: http://peer1/eureka/ + + +In this example we have a YAML file that can be used to run the same +server on 2 hosts (peer1 and peer2), by running it in different +Spring profiles. You could use this configuration to test the peer +awareness on a single host (there’s not much value in doing that in +production) by manipulating /etc/hosts to resolve the host names. In +fact, the eureka.instance.hostname is not needed if you are running +on a machine that knows its own hostname (it is looked up using +java.net.InetAddress by default). +You can add multiple peers to a system, and as long as they are all +directly connected to each other, they will synchronize +the registrations amongst themselves. + +application.yml (Three Peer Aware Eureka Servers) + +eureka: + client: + serviceUrl: + defaultZone: http://peer1/eureka/,http://peer2/eureka/,http://peer3/eureka/ + +--- +spring: + profiles: peer1 +eureka: + instance: + hostname: peer1 + +--- +spring: + profiles: peer2 +eureka: + instance: + hostname: peer2 + +--- +spring: + profiles: peer3 +eureka: + instance: + hostname: peer3 + + +
+
+Prefer IP Address +In some cases, it is preferable for Eureka to advertise the IP Adresses +of services rather than the hostname. Set eureka.instance.preferIpAddress +to true and when the application registers with eureka, it will use its +IP Address rather than its hostname. + +If hostname can’t be determined by Java, then IP address is sent to Eureka. +Only explict way of setting hostname is by using eureka.instance.hostname. +You can set your hostname at the run time using environment variable, for +example eureka.instance.hostname=${HOST_NAME}. + +
+ + +Circuit Breaker: Hystrix Clients +Netflix has created a library called Hystrix that implements the circuit breaker pattern. In a microservice architecture it is common to have multiple layers of service calls. +
+Microservice Graph + + + + +Hystrix + +
+A service failure in the lower level of services can cause cascading failure all the way up to the user. When calls to a particular service is greater than circuitBreaker.requestVolumeThreshold (default: 20 requests) and failue percentage is greater than circuitBreaker.errorThresholdPercentage (default: >50%) in a rolling window defined by metrics.rollingStats.timeInMilliseconds (default: 10 seconds), the circuit opens and the call is not made. In cases of error and an open circuit a fallback can be provided by the developer. +
+Hystrix fallback prevents cascading failures + + + + +HystrixFallback + +
+Having an open circuit stops cascading failures and allows overwhelmed or failing services time to heal. The fallback can be another Hystrix protected call, static data or a sane empty value. Fallbacks may be chained so the first fallback makes some other business call which in turn falls back to static data. +
+How to Include Hystrix +To include Hystrix in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-hystrix. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +Example boot app: +@SpringBootApplication +@EnableCircuitBreaker +public class Application { + + public static void main(String[] args) { + new SpringApplicationBuilder(Application.class).web(true).run(args); + } + +} + +@Component +public class StoreIntegration { + + @HystrixCommand(fallbackMethod = "defaultStores") + public Object getStores(Map<String, Object> parameters) { + //do stuff that might fail + } + + public Object defaultStores(Map<String, Object> parameters) { + return /* something useful */; + } +} +The @HystrixCommand is provided by a Netflix contrib library called +"javanica". +Spring Cloud automatically wraps Spring beans with that +annotation in a proxy that is connected to the Hystrix circuit +breaker. The circuit breaker calculates when to open and close the +circuit, and what to do in case of a failure. +To configure the @HystrixCommand you can use the commandProperties +attribute with a list of @HystrixProperty annotations. See +here +for more details. See the Hystrix wiki +for details on the properties available. +
+
+Propagating the Security Context or using Spring Scopes +If you want some thread local context to propagate into a @HystrixCommand the default declaration will not work because it executes the command in a thread pool (in case of timeouts). You can switch Hystrix to use the same thread as the caller using some configuration, or directly in the annotation, by asking it to use a different "Isolation Strategy". For example: +@HystrixCommand(fallbackMethod = "stubMyService", + commandProperties = { + @HystrixProperty(name="execution.isolation.strategy", value="SEMAPHORE") + } +) +... +The same thing applies if you are using @SessionScope or @RequestScope. You will know when you need to do this because of a runtime exception that says it can’t find the scoped context. +You also have the option to set the hystrix.shareSecurityContext property to true. Doing so will auto configure an Hystrix concurrency strategy plugin hook who will transfer the SecurityContext from your main thread to the one used by the Hystrix command. Hystrix does not allow multiple hystrix concurrency strategy to be registered so an extension mechanism is available by declaring your own HystrixConcurrencyStrategy as a Spring bean. Spring Cloud will lookup for your implementation within the Spring context and wrap it inside its own plugin. +
+
+Health Indicator +The state of the connected circuit breakers are also exposed in the +/health endpoint of the calling application. +{ + "hystrix": { + "openCircuitBreakers": [ + "StoreIntegration::getStoresByLocationLink" + ], + "status": "CIRCUIT_OPEN" + }, + "status": "UP" +} +
+
+Hystrix Metrics Stream +To enable the Hystrix metrics stream include a dependency on spring-boot-starter-actuator. This will expose the /hystrix.stream as a management endpoint. + <dependency> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-starter-actuator</artifactId> + </dependency> +
+ + +Circuit Breaker: Hystrix Dashboard +One of the main benefits of Hystrix is the set of metrics it gathers about each HystrixCommand. The Hystrix Dashboard displays the health of each circuit breaker in an efficient manner. +
+Hystrix Dashboard + + + + +Hystrix + +
+ + +Hystrix Timeouts And Ribbon Clients +When using Hystrix commands that wrap Ribbon clients you want to make sure your Hystrix timeout +is configured to be longer than the configured Ribbon timeout, including any potential +retries that might be made. For example, if your Ribbon connection timeout is one second and +the Ribbon client might retry the request three times, than your Hystrix timeout should +be slightly more than three seconds. +
+How to Include Hystrix Dashboard +To include the Hystrix Dashboard in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-hystrix-dashboard. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +To run the Hystrix Dashboard annotate your Spring Boot main class with @EnableHystrixDashboard. You then visit /hystrix and point the dashboard to an individual instances /hystrix.stream endpoint in a Hystrix client application. + +When connecting to a /hystrix.stream endpoint which uses HTTPS the certificate used by the server +must be trusted by the JVM. If the certificate is not trusted you must import the certificate into the JVM +in order for the Hystrix Dashboard to make a successful connection to the stream endpoint. + +
+
+Turbine +Looking at an individual instances Hystrix data is not very useful in terms of the overall health of the system. Turbine is an application that aggregates all of the relevant /hystrix.stream endpoints into a combined /turbine.stream for use in the Hystrix Dashboard. Individual instances are located via Eureka. Running Turbine is as simple as annotating your main class with the @EnableTurbine annotation (e.g. using spring-cloud-starter-netflix-turbine to set up the classpath). All of the documented configuration properties from the Turbine 1 wiki apply. The only difference is that the turbine.instanceUrlSuffix does not need the port prepended as this is handled automatically unless turbine.instanceInsertPort=false. + +By default, Turbine looks for the /hystrix.stream endpoint on a registered instance by looking up its hostName and port entries in Eureka, then appending /hystrix.stream to it. +If the instance’s metadata contains management.port, it will be used instead of the port value for the /hystrix.stream endpoint. +By default, metadata entry management.port is equal to the management.port configuration property, it can be overridden though with following configuration: + +eureka: + instance: + metadata-map: + management.port: ${management.port:8081} +The configuration key turbine.appConfig is a list of eureka serviceIds that turbine will use to lookup instances. The turbine stream is then used in the Hystrix dashboard using a url that looks like: https://my.turbine.sever:8080/turbine.stream?cluster=CLUSTERNAME (the cluster parameter can be omitted if the name is "default"). The cluster parameter must match an entry in turbine.aggregator.clusterConfig. Values returned from eureka are uppercase, thus we expect this example to work if there is an app registered with Eureka called "customers": +turbine: + aggregator: + clusterConfig: CUSTOMERS + appConfig: customers +If you need to customize which cluster names should be used by Turbine (you don’t want to store cluster names in +turbine.aggregator.clusterConfig configuration) provide a bean of type TurbineClustersProvider. +The clusterName can be customized by a SPEL expression in turbine.clusterNameExpression with root an instance of InstanceInfo. The default value is appName, which means that the Eureka serviceId ends up as the cluster key (i.e. the InstanceInfo for customers has an appName of "CUSTOMERS"). A different example would be turbine.clusterNameExpression=aSGName, which would get the cluster name from the AWS ASG name. Another example: +turbine: + aggregator: + clusterConfig: SYSTEM,USER + appConfig: customers,stores,ui,admin + clusterNameExpression: metadata['cluster'] +In this case, the cluster name from 4 services is pulled from their metadata map, and is expected to have values that include "SYSTEM" and "USER". +To use the "default" cluster for all apps you need a string literal expression (with single quotes, and escaped with double quotes if it is in YAML as well): +turbine: + appConfig: customers,stores + clusterNameExpression: "'default'" +Spring Cloud provides a spring-cloud-starter-netflix-turbine that has all the dependencies you need to get a Turbine server running. Just create a Spring Boot application and annotate it with @EnableTurbine. + +by default Spring Cloud allows Turbine to use the host and port to allow multiple processes per host, per cluster. If you want the native Netflix behaviour built into Turbine that does not allow multiple processes per host, per cluster (the key to the instance id is the hostname), then set the property turbine.combineHostPort=false. + +
+
+Turbine Stream +In some environments (e.g. in a PaaS setting), the classic Turbine model of pulling metrics from all the distributed Hystrix commands doesn’t work. In that case you might want to have your Hystrix commands push metrics to Turbine, and Spring Cloud enables that with messaging. All you need to do on the client is add a dependency to spring-cloud-netflix-hystrix-stream and the spring-cloud-starter-stream-* of your choice (see Spring Cloud Stream documentation for details on the brokers, and how to configure the client credentials, but it should work out of the box for a local broker). +On the server side Just create a Spring Boot application and annotate it with @EnableTurbineStream and by default it will come up on port 8989 (point your Hystrix dashboard to that port, any path). You can customize the port using either server.port or turbine.stream.port. If you have spring-boot-starter-web and spring-boot-starter-actuator on the classpath as well, then you can open up the Actuator endpoints on a separate port (with Tomcat by default) by providing a management.port which is different. +You can then point the Hystrix Dashboard to the Turbine Stream Server instead of individual Hystrix streams. If Turbine Stream is running on port 8989 on myhost, then put http://myhost:8989 in the stream input field in the Hystrix Dashboard. Circuits will be prefixed by their respective serviceId, followed by a dot, then the circuit name. +Spring Cloud provides a spring-cloud-starter-netflix-turbine-stream that has all the dependencies you need to get a Turbine Stream server running - just add the Stream binder of your choice, e.g. spring-cloud-starter-stream-rabbit. You need Java 8 to run the app because it is Netty-based. +Turbine Stream server also supports the cluster parameter. +Unlike Turbine server, Turbine Stream uses eureka serviceIds as cluster names and these are not configurable. +If Turbine Stream server is running on port 8989 on my.turbine.server and you have two eureka serviceIds customers and products in your environment, the following URLs will be available on your Turbine Stream server. default and empty cluster name will provide all metrics that Turbine Stream server receives. +https://my.turbine.sever:8989/turbine.stream?cluster=customers +https://my.turbine.sever:8989/turbine.stream?cluster=products +https://my.turbine.sever:8989/turbine.stream?cluster=default +https://my.turbine.sever:8989/turbine.stream +So, you can use eureka serviceIds as cluster names for your Turbine dashboard (or any compatible dashboard). +You don’t need to configure any properties like turbine.appConfig, turbine.clusterNameExpression and turbine.aggregator.clusterConfig for your Turbine Stream server. + +Turbine Stream server gathers all metrics from the configured input channel with Spring Cloud Stream. It means that it doesn’t gather Hystrix metrics actively from each instance. It just can provide metrics that were already gathered into the input channel by each instance. + +
+ + +Client Side Load Balancer: Ribbon +Ribbon is a client side load balancer which gives you a lot of control +over the behaviour of HTTP and TCP clients. Feign already uses Ribbon, +so if you are using @FeignClient then this section also applies. +A central concept in Ribbon is that of the named client. Each load +balancer is part of an ensemble of components that work together to +contact a remote server on demand, and the ensemble has a name that +you give it as an application developer (e.g. using the @FeignClient +annotation). Spring Cloud creates a new ensemble as an +ApplicationContext on demand for each named client using +RibbonClientConfiguration. This contains (amongst other things) an +ILoadBalancer, a RestClient, and a ServerListFilter. +
+How to Include Ribbon +To include Ribbon in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-ribbon. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +
+
+Customizing the Ribbon Client +You can configure some bits of a Ribbon client using external +properties in <client>.ribbon.*, which is no different than using +the Netflix APIs natively, except that you can use Spring Boot +configuration files. The native options can +be inspected as static fields in CommonClientConfigKey (part of +ribbon-core). +Spring Cloud also lets you take full control of the client by +declaring additional configuration (on top of the +RibbonClientConfiguration) using @RibbonClient. Example: +@Configuration +@RibbonClient(name = "foo", configuration = FooConfiguration.class) +public class TestConfiguration { +} +In this case the client is composed from the components already in +RibbonClientConfiguration together with any in FooConfiguration +(where the latter generally will override the former). + +The FooConfiguration has to be @Configuration but take +care that it is not in a @ComponentScan for the main application +context, otherwise it will be shared by all the @RibbonClients. If +you use @ComponentScan (or @SpringBootApplication) you need to +take steps to avoid it being included (for instance put it in a +separate, non-overlapping package, or specify the packages to scan +explicitly in the @ComponentScan). + +Spring Cloud Netflix provides the following beans by default for ribbon +(BeanType beanName: ClassName): + + +IClientConfig ribbonClientConfig: DefaultClientConfigImpl + + +IRule ribbonRule: ZoneAvoidanceRule + + +IPing ribbonPing: DummyPing + + +ServerList<Server> ribbonServerList: ConfigurationBasedServerList + + +ServerListFilter<Server> ribbonServerListFilter: ZonePreferenceServerListFilter + + +ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer + + +ServerListUpdater ribbonServerListUpdater: PollingServerListUpdater + + +Creating a bean of one of those type and placing it in a @RibbonClient +configuration (such as FooConfiguration above) allows you to override each +one of the beans described. Example: +@Configuration +protected static class FooConfiguration { + @Bean + public ZonePreferenceServerListFilter serverListFilter() { + ZonePreferenceServerListFilter filter = new ZonePreferenceServerListFilter(); + filter.setZone("myTestZone"); + return filter; + } + + @Bean + public IPing ribbonPing() { + return new PingUrl(); + } +} +This replaces the NoOpPing with PingUrl and provides a custom serverListFilter +
+
+Customizing default for all Ribbon Clients +A default configuration can be provided for all Ribbon Clients using the @RibbonClients annotation and registering a default configuration as shown in the following example: +@RibbonClients(defaultConfiguration = DefaultRibbonConfig.class) +public class RibbonClientDefaultConfigurationTestsConfig { + + public static class BazServiceList extends ConfigurationBasedServerList { + public BazServiceList(IClientConfig config) { + super.initWithNiwsConfig(config); + } + } +} + +@Configuration +class DefaultRibbonConfig { + + @Bean + public IRule ribbonRule() { + return new BestAvailableRule(); + } + + @Bean + public IPing ribbonPing() { + return new PingUrl(); + } + + @Bean + public ServerList<Server> ribbonServerList(IClientConfig config) { + return new RibbonClientDefaultConfigurationTestsConfig.BazServiceList(config); + } + + @Bean + public ServerListSubsetFilter serverListFilter() { + ServerListSubsetFilter filter = new ServerListSubsetFilter(); + return filter; + } + +} +
+
+Customizing the Ribbon Client using properties +Starting with version 1.2.0, Spring Cloud Netflix now supports customizing Ribbon clients using properties to be compatible with the Ribbon documentation. +This allows you to change behavior at start up time in different environments. +The supported properties are listed below and should be prefixed by <clientName>.ribbon.: + + +NFLoadBalancerClassName: should implement ILoadBalancer + + +NFLoadBalancerRuleClassName: should implement IRule + + +NFLoadBalancerPingClassName: should implement IPing + + +NIWSServerListClassName: should implement ServerList + + +NIWSServerListFilterClassName should implement ServerListFilter + + + +Classes defined in these properties have precedence over beans defined using @RibbonClient(configuration=MyRibbonConfig.class) and the defaults provided by Spring Cloud Netflix. + +To set the IRule for a service name users you could set the following: + +application.yml + +users: + ribbon: + NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList + NFLoadBalancerRuleClassName: com.netflix.loadbalancer.WeightedResponseTimeRule + + +See the Ribbon documentation for implementations provided by Ribbon. +
+
+Using Ribbon with Eureka +When Eureka is used in conjunction with Ribbon (i.e., both are on the classpath) the ribbonServerList +is overridden with an extension of DiscoveryEnabledNIWSServerList +which populates the list of servers from Eureka. It also replaces the +IPing interface with NIWSDiscoveryPing which delegates to Eureka +to determine if a server is up. The ServerList that is installed by +default is a DomainExtractingServerList and the purpose of this is +to make physical metadata available to the load balancer without using +AWS AMI metadata (which is what Netflix relies on). By default the +server list will be constructed with "zone" information as provided in +the instance metadata (so on the remote clients set +eureka.instance.metadataMap.zone), and if that is missing it can use +the domain name from the server hostname as a proxy for zone (if the +flag approximateZoneFromHostname is set). Once the zone information +is available it can be used in a ServerListFilter. By default it +will be used to locate a server in the same zone as the client because +the default is a ZonePreferenceServerListFilter. The zone of the +client is determined the same way as the remote instances by default, +i.e. via eureka.instance.metadataMap.zone. + +The orthodox "archaius" way to set the client zone is via a +configuration property called "@zone", and Spring Cloud will use that +in preference to all other settings if it is available (note that the +key will have to be quoted in YAML configuration). + + +If there is no other source of zone data then a guess is made +based on the client configuration (as opposed to the instance +configuration). We take eureka.client.availabilityZones, which is a +map from region name to a list of zones, and pull out the first zone +for the instance’s own region (i.e. the eureka.client.region, which +defaults to "us-east-1" for comatibility with native Netflix). + +
+
+Example: How to Use Ribbon Without Eureka +Eureka is a convenient way to abstract the discovery of remote servers +so you don’t have to hard code their URLs in clients, but if you +prefer not to use it, Ribbon and Feign are still quite +amenable. Suppose you have declared a @RibbonClient for "stores", +and Eureka is not in use (and not even on the classpath). The Ribbon +client defaults to a configured server list, and you can supply the +configuration like this + +application.yml + +stores: + ribbon: + listOfServers: example.com,google.com + + +
+
+Example: Disable Eureka use in Ribbon +Setting the property ribbon.eureka.enabled = false will explicitly +disable the use of Eureka in Ribbon. + +application.yml + +ribbon: + eureka: + enabled: false + + +
+
+Using the Ribbon API Directly +You can also use the LoadBalancerClient directly. Example: +public class MyClass { + @Autowired + private LoadBalancerClient loadBalancer; + + public void doStuff() { + ServiceInstance instance = loadBalancer.choose("stores"); + URI storesUri = URI.create(String.format("http://%s:%s", instance.getHost(), instance.getPort())); + // ... do something with the URI + } +} +
+
+Caching of Ribbon Configuration +Each Ribbon named client has a corresponding child Application Context that Spring Cloud maintains, this application context is lazily loaded up on the first request to the named client. +This lazy loading behavior can be changed to instead eagerly load up these child Application contexts at startup by specifying the names of the Ribbon clients. + +application.yml + +ribbon: + eager-load: + enabled: true + clients: client1, client2, client3 + + +
+
+How to Configure Hystrix thread pools +If you change zuul.ribbonIsolationStrategy to THREAD, the thread isolation strategy for Hystrix will be used for all routes. In this case, the HystrixThreadPoolKey is set to "RibbonCommand" as default. It means that HystrixCommands for all routes will be executed in the same Hystrix thread pool. This behavior can be changed using the following configuration and it will result in HystrixCommands being executed in the Hystrix thread pool for each route. + +application.yml + +zuul: + threadPool: + useSeparateThreadPools: true + + +The default HystrixThreadPoolKey in this case is same with service ID for each route. To add a prefix to HystrixThreadPoolKey, set zuul.threadPool.threadPoolKeyPrefix to a value that you want to add. For example: + +application.yml + +zuul: + threadPool: + useSeparateThreadPools: true + threadPoolKeyPrefix: zuulgw + + +
+
+How to Provide a Key to Ribbon’s <literal>IRule</literal> +If you need to provide your own IRule implementation to handle a special routing requirement like a canary test, +you probably want to pass some information to the choose method of IRule. + +com.netflix.loadbalancer.IRule.java + +public interface IRule{ + public Server choose(Object key); + : + + +You can provide some information that will be used to choose a target server by your IRule implementation like +the following: +RequestContext.getCurrentContext() + .set(FilterConstants.LOAD_BALANCER_KEY, "canary-test"); +If you put any object into the RequestContext with a key FilterConstants.LOAD_BALANCER_KEY, it will +be passed to the choose method of IRule implementation. Above code must be executed before RibbonRoutingFilter +is executed and Zuul’s pre filter is the best place to do that. You can easily access HTTP headers and query parameters +via RequestContext in pre filter, so it can be used to determine LOAD_BALANCER_KEY that will be passed to Ribbon. +If you don’t put any value with LOAD_BALANCER_KEY in RequestContext, null will be passed as a parameter of choose +method. +
+ + +Declarative REST Client: Feign +Feign is a declarative web service client. It makes writing web service clients easier. To use Feign create an interface and annotate it. It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders. Spring Cloud adds support for Spring MVC annotations and for using the same HttpMessageConverters used by default in Spring Web. Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign. +
+How to Include Feign +To include Feign in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-openfeign. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +Example spring boot app +@Configuration +@ComponentScan +@EnableAutoConfiguration +@EnableFeignClients +public class Application { + + public static void main(String[] args) { + SpringApplication.run(Application.class, args); + } + +} + +StoreClient.java + +@FeignClient("stores") +public interface StoreClient { + @RequestMapping(method = RequestMethod.GET, value = "/stores") + List<Store> getStores(); + + @RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json") + Store update(@PathVariable("storeId") Long storeId, Store store); +} + + +In the @FeignClient annotation the String value ("stores" above) is +an arbitrary client name, which is used to create a Ribbon load +balancer (see below for details of Ribbon +support). You can also specify a URL using the url attribute +(absolute value or just a hostname). The name of the bean in the +application context is the fully qualified name of the interface. +To specify your own alias value you can use the qualifier value +of the @FeignClient annotation. +The Ribbon client above will want to discover the physical addresses +for the "stores" service. If your application is a Eureka client then +it will resolve the service in the Eureka service registry. If you +don’t want to use Eureka, you can simply configure a list of servers +in your external configuration (see +above for example). +
+
+Overriding Feign Defaults +A central concept in Spring Cloud’s Feign support is that of the named client. Each feign client is part of an ensemble of components that work together to contact a remote server on demand, and the ensemble has a name that you give it as an application developer using the @FeignClient annotation. Spring Cloud creates a new ensemble as an +ApplicationContext on demand for each named client using FeignClientsConfiguration. This contains (amongst other things) an feign.Decoder, a feign.Encoder, and a feign.Contract. +Spring Cloud lets you take full control of the feign client by declaring additional configuration (on top of the FeignClientsConfiguration) using @FeignClient. Example: +@FeignClient(name = "stores", configuration = FooConfiguration.class) +public interface StoreClient { + //.. +} +In this case the client is composed from the components already in FeignClientsConfiguration together with any in FooConfiguration (where the latter will override the former). + +FooConfiguration does not need to be annotated with @Configuration. However, if it is, then take care to exclude it from any @ComponentScan that would otherwise include this configuration as it will become the default source for feign.Decoder, feign.Encoder, feign.Contract, etc., when specified. This can be avoided by putting it in a separate, non-overlapping package from any @ComponentScan or @SpringBootApplication, or it can be explicitly excluded in @ComponentScan. + + +The serviceId attribute is now deprecated in favor of the name attribute. + + +Previously, using the url attribute, did not require the name attribute. Using name is now required. + +Placeholders are supported in the name and url attributes. +@FeignClient(name = "${feign.name}", url = "${feign.url}") +public interface StoreClient { + //.. +} +Spring Cloud Netflix provides the following beans by default for feign (BeanType beanName: ClassName): + + +Decoder feignDecoder: ResponseEntityDecoder (which wraps a SpringDecoder) + + +Encoder feignEncoder: SpringEncoder + + +Logger feignLogger: Slf4jLogger + + +Contract feignContract: SpringMvcContract + + +Feign.Builder feignBuilder: HystrixFeign.Builder + + +Client feignClient: if Ribbon is enabled it is a LoadBalancerFeignClient, otherwise the default feign client is used. + + +The OkHttpClient and ApacheHttpClient feign clients can be used by setting feign.okhttp.enabled or feign.httpclient.enabled to true, respectively, and having them on the classpath. +You can customize the HTTP client used by providing a bean of either ClosableHttpClient when using Apache or OkHttpClient whe using OK HTTP. +Spring Cloud Netflix does not provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client: + + +Logger.Level + + +Retryer + + +ErrorDecoder + + +Request.Options + + +Collection<RequestInterceptor> + + +SetterFactory + + +Creating a bean of one of those type and placing it in a @FeignClient configuration (such as FooConfiguration above) allows you to override each one of the beans described. Example: +@Configuration +public class FooConfiguration { + @Bean + public Contract feignContract() { + return new feign.Contract.Default(); + } + + @Bean + public BasicAuthRequestInterceptor basicAuthRequestInterceptor() { + return new BasicAuthRequestInterceptor("user", "password"); + } +} +This replaces the SpringMvcContract with feign.Contract.Default and adds a RequestInterceptor to the collection of RequestInterceptor. +@FeignClient also can be configured using configuration properties. +application.yml +feign: + client: + config: + feignName: + connectTimeout: 5000 + readTimeout: 5000 + loggerLevel: full + errorDecoder: com.example.SimpleErrorDecoder + retryer: com.example.SimpleRetryer + requestInterceptors: + - com.example.FooRequestInterceptor + - com.example.BarRequestInterceptor + decode404: false +Default configurations can be specified in the @EnableFeignClients attribute defaultConfiguration in a similar manner as described above. The difference is that this configuration will apply to all feign clients. +If you prefer using configuration properties to configured all @FeignClient, you can create configuration properties with default feign name. +application.yml +feign: + client: + config: + default: + connectTimeout: 5000 + readTimeout: 5000 + loggerLevel: basic +If we create both @Configuration bean and configuration properties, configuration properties will win. +It will override @Configuration values. But if you want to change the priority to @Configuration, +you can change feign.client.default-to-properties to false. + +If you need to use ThreadLocal bound variables in your RequestInterceptor`s you will need to either set the +thread isolation strategy for Hystrix to `SEMAPHORE or disable Hystrix in Feign. + +application.yml +# To disable Hystrix in Feign +feign: + hystrix: + enabled: false + +# To set thread isolation to SEMAPHORE +hystrix: + command: + default: + execution: + isolation: + strategy: SEMAPHORE +
+
+Creating Feign Clients Manually +In some cases it might be necessary to customize your Feign Clients in a way that is not +possible using the methods above. In this case you can create Clients using the +Feign Builder API. Below is an example +which creates two Feign Clients with the same interface but configures each one with +a separate request interceptor. +@Import(FeignClientsConfiguration.class) +class FooController { + + private FooClient fooClient; + + private FooClient adminClient; + + @Autowired + public FooController( + Decoder decoder, Encoder encoder, Client client) { + this.fooClient = Feign.builder().client(client) + .encoder(encoder) + .decoder(decoder) + .requestInterceptor(new BasicAuthRequestInterceptor("user", "user")) + .target(FooClient.class, "http://PROD-SVC"); + this.adminClient = Feign.builder().client(client) + .encoder(encoder) + .decoder(decoder) + .requestInterceptor(new BasicAuthRequestInterceptor("admin", "admin")) + .target(FooClient.class, "http://PROD-SVC"); + } +} + +In the above example FeignClientsConfiguration.class is the default configuration +provided by Spring Cloud Netflix. + + +PROD-SVC is the name of the service the Clients will be making requests to. + +
+
+Feign Hystrix Support +If Hystrix is on the classpath and feign.hystrix.enabled=true, Feign will wrap all methods with a circuit breaker. Returning a com.netflix.hystrix.HystrixCommand is also available. This lets you use reactive patterns (with a call to .toObservable() or .observe() or asynchronous use (with a call to .queue()). +To disable Hystrix support on a per-client basis create a vanilla Feign.Builder with the "prototype" scope, e.g.: +@Configuration +public class FooConfiguration { + @Bean + @Scope("prototype") + public Feign.Builder feignBuilder() { + return Feign.builder(); + } +} + +Prior to the Spring Cloud Dalston release, if Hystrix was on the classpath Feign would have wrapped +all methods in a circuit breaker by default. This default behavior was changed in Spring Cloud Dalston in +favor for an opt-in approach. + +
+
+Feign Hystrix Fallbacks +Hystrix supports the notion of a fallback: a default code path that is executed when they circuit is open or there is an error. To enable fallbacks for a given @FeignClient set the fallback attribute to the class name that implements the fallback. You also need to declare your implementation as a Spring bean. +@FeignClient(name = "hello", fallback = HystrixClientFallback.class) +protected interface HystrixClient { + @RequestMapping(method = RequestMethod.GET, value = "/hello") + Hello iFailSometimes(); +} + +static class HystrixClientFallback implements HystrixClient { + @Override + public Hello iFailSometimes() { + return new Hello("fallback"); + } +} +If one needs access to the cause that made the fallback trigger, one can use the fallbackFactory attribute inside @FeignClient. +@FeignClient(name = "hello", fallbackFactory = HystrixClientFallbackFactory.class) +protected interface HystrixClient { + @RequestMapping(method = RequestMethod.GET, value = "/hello") + Hello iFailSometimes(); +} + +@Component +static class HystrixClientFallbackFactory implements FallbackFactory<HystrixClient> { + @Override + public HystrixClient create(Throwable cause) { + return new HystrixClient() { + @Override + public Hello iFailSometimes() { + return new Hello("fallback; reason was: " + cause.getMessage()); + } + }; + } +} + +There is a limitation with the implementation of fallbacks in Feign and how Hystrix fallbacks work. Fallbacks are currently not supported for methods that return com.netflix.hystrix.HystrixCommand and rx.Observable. + +
+
+Feign and <literal>@Primary</literal> +When using Feign with Hystrix fallbacks, there are multiple beans in the ApplicationContext of the same type. This will cause @Autowired to not work because there isn’t exactly one bean, or one marked as primary. To work around this, Spring Cloud Netflix marks all Feign instances as @Primary, so Spring Framework will know which bean to inject. In some cases, this may not be desirable. To turn off this behavior set the primary attribute of @FeignClient to false. +@FeignClient(name = "hello", primary = false) +public interface HelloClient { + // methods here +} +
+
+Feign Inheritance Support +Feign supports boilerplate apis via single-inheritance interfaces. +This allows grouping common operations into convenient base interfaces. + +UserService.java + +public interface UserService { + + @RequestMapping(method = RequestMethod.GET, value ="/users/{id}") + User getUser(@PathVariable("id") long id); +} + + + +UserResource.java + +@RestController +public class UserResource implements UserService { + +} + + + +UserClient.java + +package project.user; + +@FeignClient("users") +public interface UserClient extends UserService { + +} + + + +It is generally not advisable to share an interface between a +server and a client. It introduces tight coupling, and also actually +doesn’t work with Spring MVC in its current form (method parameter +mapping is not inherited). + +
+
+Feign request/response compression +You may consider enabling the request or response GZIP compression for your +Feign requests. You can do this by enabling one of the properties: +feign.compression.request.enabled=true +feign.compression.response.enabled=true +Feign request compression gives you settings similar to what you may set for your web server: +feign.compression.request.enabled=true +feign.compression.request.mime-types=text/xml,application/xml,application/json +feign.compression.request.min-request-size=2048 +These properties allow you to be selective about the compressed media types and minimum request threshold length. +
+
+Feign logging +A logger is created for each Feign client created. By default the name of the logger is the full class name of the interface used to create the Feign client. Feign logging only responds to the DEBUG level. + +application.yml + +logging.level.project.user.UserClient: DEBUG + + +The Logger.Level object that you may configure per client, tells Feign how much to log. Choices are: + + +NONE, No logging (DEFAULT). + + +BASIC, Log only the request method and URL and the response status code and execution time. + + +HEADERS, Log the basic information along with request and response headers. + + +FULL, Log the headers, body, and metadata for both requests and responses. + + +For example, the following would set the Logger.Level to FULL: +@Configuration +public class FooConfiguration { + @Bean + Logger.Level feignLoggerLevel() { + return Logger.Level.FULL; + } +} +
+ + +External Configuration: Archaius +Archaius is the Netflix client side configuration library. It is the library used by all of the Netflix OSS components for configuration. Archaius is an extension of the Apache Commons Configuration project. It allows updates to configuration by either polling a source for changes or for a source to push changes to the client. Archaius uses Dynamic<Type>Property classes as handles to properties. + +Archaius Example + +class ArchaiusTest { + DynamicStringProperty myprop = DynamicPropertyFactory + .getInstance() + .getStringProperty("my.prop"); + + void doSomething() { + OtherClass.someMethod(myprop.get()); + } +} + + +Archaius has its own set of configuration files and loading priorities. Spring applications should generally not use Archaius directly, but the need to configure the Netflix tools natively remains. Spring Cloud has a Spring Environment Bridge so Archaius can read properties from the Spring Environment. This allows Spring Boot projects to use the normal configuration toolchain, while allowing them to configure the Netflix tools, for the most part, as documented. + + +Router and Filter: Zuul +Routing in an integral part of a microservice architecture. For example, / may be mapped to your web application, /api/users is mapped to the user service and /api/shop is mapped to the shop service. Zuul is a JVM based router and server side load balancer by Netflix. +Netflix uses Zuul for the following: + + +Authentication + + +Insights + + +Stress Testing + + +Canary Testing + + +Dynamic Routing + + +Service Migration + + +Load Shedding + + +Security + + +Static Response handling + + +Active/Active traffic management + + +Zuul’s rule engine allows rules and filters to be written in essentially any JVM language, with built in support for Java and Groovy. + +The configuration property zuul.max.host.connections has been replaced by two new properties, zuul.host.maxTotalConnections and zuul.host.maxPerRouteConnections which default to 200 and 20 respectively. + + +Default Hystrix isolation pattern (ExecutionIsolationStrategy) for all routes is SEMAPHORE. zuul.ribbonIsolationStrategy can be changed to THREAD if this isolation pattern is preferred. + +
+How to Include Zuul +To include Zuul in your project use the starter with group org.springframework.cloud +and artifact id spring-cloud-starter-netflix-zuul. See the Spring Cloud Project page +for details on setting up your build system with the current Spring Cloud Release Train. +
+
+Embedded Zuul Reverse Proxy +Spring Cloud has created an embedded Zuul proxy to ease the +development of a very common use case where a UI application wants to +proxy calls to one or more back end services. This feature is useful +for a user interface to proxy to the backend services it requires, +avoiding the need to manage CORS and authentication concerns +independently for all the backends. +To enable it, annotate a Spring Boot main class with +@EnableZuulProxy, and this forwards local calls to the appropriate +service. By convention, a service with the ID "users", will +receive requests from the proxy located at /users (with the prefix +stripped). The proxy uses Ribbon to locate an instance to forward to +via discovery, and all requests are executed in a +hystrix command, so +failures will show up in Hystrix metrics, and once the circuit is open +the proxy will not try to contact the service. + +the Zuul starter does not include a discovery client, so for +routes based on service IDs you need to provide one of those +on the classpath as well (e.g. Eureka is one choice). + +To skip having a service automatically added, set +zuul.ignored-services to a list of service id patterns. If a service +matches a pattern that is ignored, but also included in the explicitly +configured routes map, then it will be unignored. Example: + +application.yml + + zuul: + ignoredServices: '*' + routes: + users: /myusers/** + + +In this example, all services are ignored except "users". +To augment or change +the proxy routes, you can add external configuration like the +following: + +application.yml + + zuul: + routes: + users: /myusers/** + + +This means that http calls to "/myusers" get forwarded to the "users" +service (for example "/myusers/101" is forwarded to "/101"). +To get more fine-grained control over a route you can specify the path +and the serviceId independently: + +application.yml + + zuul: + routes: + users: + path: /myusers/** + serviceId: users_service + + +This means that http calls to "/myusers" get forwarded to the +"users_service" service. The route has to have a "path" which can be +specified as an ant-style pattern, so "/myusers/*" only matches one +level, but "/myusers/**" matches hierarchically. +The location of the backend can be specified as either a "serviceId" +(for a service from discovery) or a "url" (for a physical location), e.g. + +application.yml + + zuul: + routes: + users: + path: /myusers/** + url: https://example.com/users_service + + +These simple url-routes don’t get executed as a HystrixCommand nor do they loadbalance multiple URLs with Ribbon. +To achieve this, you can specify a serviceId with a static list of servers: + +application.yml + +zuul: + routes: + echo: + path: /myusers/** + serviceId: myusers-service + stripPrefix: true + +hystrix: + command: + myusers-service: + execution: + isolation: + thread: + timeoutInMilliseconds: ... + +myusers-service: + ribbon: + NIWSServerListClassName: com.netflix.loadbalancer.ConfigurationBasedServerList + listOfServers: https://example1.com,http://example2.com + ConnectTimeout: 1000 + ReadTimeout: 3000 + MaxTotalHttpConnections: 500 + MaxConnectionsPerHost: 100 + + +Another method is specifiying a service-route and configure a Ribbon client for the +serviceId (this requires disabling Eureka support in Ribbon: +see above for more information), e.g. + +application.yml + +zuul: + routes: + users: + path: /myusers/** + serviceId: users + +ribbon: + eureka: + enabled: false + +users: + ribbon: + listOfServers: example.com,google.com + + +You can provide convention between serviceId and routes using +regexmapper. It uses regular expression named groups to extract +variables from serviceId and inject them into a route pattern. + +ApplicationConfiguration.java + +@Bean +public PatternServiceRouteMapper serviceRouteMapper() { + return new PatternServiceRouteMapper( + "(?<name>^.+)-(?<version>v.+$)", + "${version}/${name}"); +} + + +This means that a serviceId "myusers-v1" will be mapped to route +"/v1/myusers/**". Any regular expression is accepted but all named +groups must be present in both servicePattern and routePattern. If +servicePattern does not match a serviceId, the default behavior is +used. In the example above, a serviceId "myusers" will be mapped to route +"/myusers/**" (no version detected) This feature is disabled by +default and only applies to discovered services. +To add a prefix to all mappings, set zuul.prefix to a value, such as +/api. The proxy prefix is stripped from the request before the +request is forwarded by default (switch this behaviour off with +zuul.stripPrefix=false). You can also switch off the stripping of +the service-specific prefix from individual routes, e.g. + +application.yml + + zuul: + routes: + users: + path: /myusers/** + stripPrefix: false + + + +zuul.stripPrefix only applies to the prefix set in zuul.prefix. It does not have any effect on prefixes +defined within a given route’s path. + +In this example, requests to "/myusers/101" will be forwarded to "/myusers/101" on the "users" service. +The zuul.routes entries actually bind to an object of type ZuulProperties. If you +look at the properties of that object you will see that it also has a "retryable" flag. +Set that flag to "true" to have the Ribbon client automatically retry failed requests +(and if you need to you can modify the parameters of the retry operations using +the Ribbon client configuration). +The X-Forwarded-Host header is added to the forwarded requests by +default. To turn it off set zuul.addProxyHeaders = false. The +prefix path is stripped by default, and the request to the backend +picks up a header "X-Forwarded-Prefix" ("/myusers" in the examples +above). +An application with @EnableZuulProxy could act as a standalone +server if you set a default route ("/"), for example zuul.route.home: +/ would route all traffic (i.e. "/**") to the "home" service. +If more fine-grained ignoring is needed, you can specify specific patterns to ignore. +These patterns are evaluated at the start of the route location process, which +means prefixes should be included in the pattern to warrant a match. Ignored patterns +span all services and supersede any other route specification. + +application.yml + + zuul: + ignoredPatterns: /**/admin/** + routes: + users: /myusers/** + + +This means that all calls such as "/myusers/101" will be forwarded to "/101" on the "users" service. +But calls including "/admin/" will not resolve. + +If you need your routes to have their order preserved you need to use a YAML +file as the ordering will be lost using a properties file. For example: + + +application.yml + + zuul: + routes: + users: + path: /myusers/** + legacy: + path: /** + + +If you were to use a properties file, the legacy path may end up in front of the users +path rendering the users path unreachable. +
+
+Zuul Http Client +The default HTTP client used by zuul is now backed by the Apache HTTP Client instead of the +deprecated Ribbon RestClient. To use RestClient or to use the okhttp3.OkHttpClient set +ribbon.restclient.enabled=true or ribbon.okhttp.enabled=true respectively. If you would +like to customize the Apache HTTP client or the OK HTTP client provide a bean of type +ClosableHttpClient or OkHttpClient. +
+
+Cookies and Sensitive Headers +It’s OK to share headers between services in the same system, but you +probably don’t want sensitive headers leaking downstream into external +servers. You can specify a list of ignored headers as part of the +route configuration. Cookies play a special role because they have +well-defined semantics in browsers, and they are always to be treated +as sensitive. If the consumer of your proxy is a browser, then cookies +for downstream services also cause problems for the user because they +all get jumbled up (all downstream services look like they come from +the same place). +If you are careful with the design of your services, for example if +only one of the downstream services sets cookies, then you might be +able to let them flow from the backend all the way up to the +caller. Also, if your proxy sets cookies and all your back end +services are part of the same system, it can be natural to simply +share them (and for instance use Spring Session to link them up to some +shared state). Other than that, any cookies that get set by downstream +services are likely to be not very useful to the caller, so it is +recommended that you make (at least) "Set-Cookie" and "Cookie" into +sensitive headers for routes that are not part of your domain. Even +for routes that are part of your domain, try to think carefully +about what it means before allowing cookies to flow between them and +the proxy. +The sensitive headers can be configured as a comma-separated list per +route, e.g. + +application.yml + + zuul: + routes: + users: + path: /myusers/** + sensitiveHeaders: Cookie,Set-Cookie,Authorization + url: https://downstream + + + +this is the default value for sensitiveHeaders, so you don’t +need to set it unless you want it to be different. N.B. this is new in +Spring Cloud Netflix 1.1 (in 1.0 the user had no control over headers +and all cookies flow in both directions). + +The sensitiveHeaders are a blacklist and the default is not empty, +so to make Zuul send all headers (except the "ignored" ones) you would +have to explicitly set it to the empty list. This is necessary if you +want to pass cookie or authorization headers to your back end. Example: + +application.yml + + zuul: + routes: + users: + path: /myusers/** + sensitiveHeaders: + url: https://downstream + + +Sensitive headers can also be set globally by setting zuul.sensitiveHeaders. If sensitiveHeaders is set on a route, this will override the global sensitiveHeaders setting. +
+
+Ignored Headers +In addition to the per-route sensitive headers, you can set a global +value for zuul.ignoredHeaders for values that should be discarded +(both request and response) during interactions with downstream +services. By default these are empty, if Spring Security is not on the +classpath, and otherwise they are initialized to a set of well-known +"security" headers (e.g. involving caching) as specified by Spring +Security. The assumption in this case is that the downstream services +might add these headers too, and we want the values from the proxy. +To not discard these well known security headers in case Spring Security is on the classpath you can set zuul.ignoreSecurityHeaders to false. This can be useful if you disabled the HTTP Security response headers in Spring Security and want the values provided by downstream services +
+
+Management Endpoints +If you are using @EnableZuulProxy with the Spring Boot Actuator you +will enable (by default) two additional endpoints: + + +Routes + + +Filters + + +
+Routes Endpoint +A GET to the routes endpoint at /routes will return a list of the mapped +routes: + +GET /routes + +{ + /stores/**: "http://localhost:8081" +} + + +Additional route details can be requested by adding the ?format=details query +string to /routes. This will produce the following output: + +GET /routes?format=details + +{ + "/stores/**": { + "id": "stores", + "fullPath": "/stores/**", + "location": "http://localhost:8081", + "path": "/**", + "prefix": "/stores", + "retryable": false, + "customSensitiveHeaders": false, + "prefixStripped": true + } +} + + +A POST will force a refresh of the existing routes (e.g. in +case there have been changes in the service catalog). You can disable +this endpoint by setting endpoints.routes.enabled to false. + +the routes should respond automatically to changes in the +service catalog, but the POST to /routes is a way to force the change +to happen immediately. + +
+
+Filters Endpoint +A GET to the filters endpoint at /filters will return a map of Zuul +filters by type. For each filter type in the map, you will find a list +of all the filters of that type, along with their details. +
+
+
+Strangulation Patterns and Local Forwards +A common pattern when migrating an existing application or API is to +"strangle" old endpoints, slowly replacing them with different +implementations. The Zuul proxy is a useful tool for this because you +can use it to handle all traffic from clients of the old endpoints, +but redirect some of the requests to new ones. +Example configuration: + +application.yml + + zuul: + routes: + first: + path: /first/** + url: https://first.example.com + second: + path: /second/** + url: forward:/second + third: + path: /third/** + url: forward:/3rd + legacy: + path: /** + url: https://legacy.example.com + + +In this example we are strangling the "legacy" app which is mapped to +all requests that do not match one of the other patterns. Paths in +/first/** have been extracted into a new service with an external +URL. And paths in /second/** are forwarded so they can be handled +locally, e.g. with a normal Spring @RequestMapping. Paths in +/third/** are also forwarded, but with a different prefix +(i.e. /third/foo is forwarded to /3rd/foo). + +The ignored patterns aren’t completely ignored, they just +aren’t handled by the proxy (so they are also effectively forwarded +locally). + +
+
+Uploading Files through Zuul +If you @EnableZuulProxy you can use the proxy paths to +upload files and it should just work as long as the files +are small. For large files there is an alternative path +which bypasses the Spring DispatcherServlet (to +avoid multipart processing) in "/zuul/*". I.e. if +zuul.routes.customers=/customers/** then you can +POST large files to "/zuul/customers/*". The servlet +path is externalized via zuul.servletPath. Extremely +large files will also require elevated timeout settings +if the proxy route takes you through a Ribbon load +balancer, e.g. + +application.yml + +hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 60000 +ribbon: + ConnectTimeout: 3000 + ReadTimeout: 60000 + + +Note that for streaming to work with large files, you need to use chunked encoding in the request (which some browsers +do not do by default). E.g. on the command line: +$ curl -v -H "Transfer-Encoding: chunked" \ + -F "file=@mylarge.iso" localhost:9999/zuul/simple/file +
+
+Query String Encoding +When processing the incoming request, query params are decoded so they can be available for possible modifications in +Zuul filters. They are then re-encoded when building the backend request in the route filters. The result +can be different than the original input if it was encoded using Javascript’s encodeURIComponent() method for example. +While this causes no issues in most cases, some web servers can be picky with the encoding of complex query string. +To force the original encoding of the query string, it is possible to pass a special flag to ZuulProperties so +that the query string is taken as is with the HttpServletRequest::getQueryString method : + +application.yml + + zuul: + forceOriginalQueryStringEncoding: true + + +Note: This special flag only works with SimpleHostRoutingFilter and you loose the ability to easily override +query parameters with RequestContext.getCurrentContext().setRequestQueryParams(someOverriddenParameters) since +the query string is now fetched directly on the original HttpServletRequest. +
+
+Plain Embedded Zuul +You can also run a Zuul server without the proxying, or switch on parts of the proxying platform selectively, if you +use @EnableZuulServer (instead of @EnableZuulProxy). Any beans that you add to the application of type ZuulFilter +will be installed automatically, as they are with @EnableZuulProxy, but without any of the proxy filters being added +automatically. +In this case the routes into the Zuul server are still specified by +configuring "zuul.routes.*", but there is no service +discovery and no proxying, so the "serviceId" and "url" settings are +ignored. For example: + +application.yml + + zuul: + routes: + api: /api/** + + +maps all paths in "/api/**" to the Zuul filter chain. +
+
+Disable Zuul Filters +Zuul for Spring Cloud comes with a number of ZuulFilter beans enabled by default +in both proxy and server mode. See the zuul filters package for the +possible filters that are enabled. If you want to disable one, simply set +zuul.<SimpleClassName>.<filterType>.disable=true. By convention, the package after +filters is the Zuul filter type. For example to disable +org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter set +zuul.SendResponseFilter.post.disable=true. +
+
+Providing Hystrix Fallbacks For Routes +When a circuit for a given route in Zuul is tripped you can provide a fallback response +by creating a bean of type ZuulFallbackProvider. Within this bean you need to specify +the route ID the fallback is for and provide a ClientHttpResponse to return +as a fallback. Here is a very simple ZuulFallbackProvider implementation. +class MyFallbackProvider implements ZuulFallbackProvider { + @Override + public String getRoute() { + return "customers"; + } + + @Override + public ClientHttpResponse fallbackResponse() { + return new ClientHttpResponse() { + @Override + public HttpStatus getStatusCode() throws IOException { + return HttpStatus.OK; + } + + @Override + public int getRawStatusCode() throws IOException { + return 200; + } + + @Override + public String getStatusText() throws IOException { + return "OK"; + } + + @Override + public void close() { + + } + + @Override + public InputStream getBody() throws IOException { + return new ByteArrayInputStream("fallback".getBytes()); + } + + @Override + public HttpHeaders getHeaders() { + HttpHeaders headers = new HttpHeaders(); + headers.setContentType(MediaType.APPLICATION_JSON); + return headers; + } + }; + } +} +And here is what the route configuration would look like. +zuul: + routes: + customers: /customers/** +If you would like to provide a default fallback for all routes than you can create a bean of +type ZuulFallbackProvider and have the getRoute method return * or null. +class MyFallbackProvider implements ZuulFallbackProvider { + @Override + public String getRoute() { + return "*"; + } + + @Override + public ClientHttpResponse fallbackResponse() { + return new ClientHttpResponse() { + @Override + public HttpStatus getStatusCode() throws IOException { + return HttpStatus.OK; + } + + @Override + public int getRawStatusCode() throws IOException { + return 200; + } + + @Override + public String getStatusText() throws IOException { + return "OK"; + } + + @Override + public void close() { + + } + + @Override + public InputStream getBody() throws IOException { + return new ByteArrayInputStream("fallback".getBytes()); + } + + @Override + public HttpHeaders getHeaders() { + HttpHeaders headers = new HttpHeaders(); + headers.setContentType(MediaType.APPLICATION_JSON); + return headers; + } + }; + } +} +If you would like to choose the response based on the cause of the failure use FallbackProvider which will replace ZuulFallbackProvder in future versions. +class MyFallbackProvider implements FallbackProvider { + + @Override + public String getRoute() { + return "*"; + } + + @Override + public ClientHttpResponse fallbackResponse(final Throwable cause) { + if (cause instanceof HystrixTimeoutException) { + return response(HttpStatus.GATEWAY_TIMEOUT); + } else { + return fallbackResponse(); + } + } + + @Override + public ClientHttpResponse fallbackResponse() { + return response(HttpStatus.INTERNAL_SERVER_ERROR); + } + + private ClientHttpResponse response(final HttpStatus status) { + return new ClientHttpResponse() { + @Override + public HttpStatus getStatusCode() throws IOException { + return status; + } + + @Override + public int getRawStatusCode() throws IOException { + return status.value(); + } + + @Override + public String getStatusText() throws IOException { + return status.getReasonPhrase(); + } + + @Override + public void close() { + } + + @Override + public InputStream getBody() throws IOException { + return new ByteArrayInputStream("fallback".getBytes()); + } + + @Override + public HttpHeaders getHeaders() { + HttpHeaders headers = new HttpHeaders(); + headers.setContentType(MediaType.APPLICATION_JSON); + return headers; + } + }; + } +} +
+
+Zuul Timeouts +
+Service Discovery Configuration +If Zuul is using service discovery there are two timeouts you need to be concerned +with, the Hystrix timeout (since all routes are wrapped in Hystrix commands by default) +and the Ribbon timeout. The Hystrix timeout needs to take into account the Ribbon +read and connect timeout PLUS the total number of retries that will happen for that +service. By default Spring Cloud Zuul will do its best to calculate the Hystrix timeout +for you UNLESS you specify the Hystrix timeout explicitly. +The Hystrix timeout is calculated using the following formula: +(ribbon.ConnectTimeout + ribbon.ReadTimeout) * (ribbon.MaxAutoRetries + 1) * (ribbon.MaxAutoRetriesNextServer + 1) +As an example, if you set the following properties in your application properties + +application.yml + +ribbon: + ReadTimeout:100 + ConnectTimeout:500 + MaxAutoRetries:1 + MaxAutoRetriesNextServer:1 + + +Then the Hystrix timeout (for all routes in this case) will be set to 2400ms. + +You can configure the Hystrix timeout for individual routes using service.ribbon.* properties. + + +If you choose to not configure the above properties than the default values will be used therefore the +default Hystrix timeout will be set to 4000ms. + +If you set hystrix.command.commandKey.execution.isolation.thread.timeoutInMilliseconds, where +commandKey is the route id, or set hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds +than these values will be used for the Hystrix timeout regardless of what you have set for the ribbon.* properties. +If you set either of these properties YOU are responsible for making sure it takes +into account the Ribbon connect and read timeouts as well as any retries that may happen. +
+
+URL Configuration +If you have configured Zuul routes by specifying URLs than you will need to use +zuul.host.connect-timeout-millis and zuul.host.socket-timeout-millis. +
+
+
+Rewriting <literal>Location</literal> header +If Zuul is fronting a web application then there may be a need to re-write the Location header when the web application redirects through a http status code of 3XX, otherwise the browser will end up redirecting to the web application’s url instead of the Zuul url. +A LocationRewriteFilter Zuul filter can be configured to re-write the Location header to the Zuul’s url, it also adds back the stripped global and route specific prefixes. The filter can be added the following way via a Spring Configuration file: +import org.springframework.cloud.netflix.zuul.filters.post.LocationRewriteFilter; +... + +@Configuration +@EnableZuulProxy +public class ZuulConfig { + @Bean + public LocationRewriteFilter locationRewriteFilter() { + return new LocationRewriteFilter(); + } +} + +Use this filter with caution though, the filter acts on the Location header of ALL 3XX response codes which may not be appropriate in all scenarios, say if the user is redirecting to an external URL. + +
+
+Zuul Developer Guide +For a general overview of how Zuul works, please see the Zuul Wiki. +
+The Zuul Servlet +Zuul is implemented as a Servlet. For the general cases, Zuul is embedded into the Spring Dispatch mechanism. This allows Spring MVC to be in control of the routing. In this case, Zuul is configured to buffer requests. If there is a need to go through Zuul without buffering requests (e.g. for large file uploads), the Servlet is also installed outside of the Spring Dispatcher. By default, this is located at /zuul. This path can be changed with the zuul.servlet-path property. +
+
+Zuul RequestContext +To pass information between filters, Zuul uses a RequestContext. Its data is held in a ThreadLocal specific to each request. Information about where to route requests, errors and the actual HttpServletRequest and HttpServletResponse are stored there. The RequestContext extends ConcurrentHashMap, so anything can be stored in the context. FilterConstants contains the keys that are used by the filters installed by Spring Cloud Netflix (more on these later). +
+
+<literal>@EnableZuulProxy</literal> vs. <literal>@EnableZuulServer</literal> +Spring Cloud Netflix installs a number of filters based on which annotation was used to enable Zuul. @EnableZuulProxy is a superset of @EnableZuulServer. In other words, @EnableZuulProxy contains all filters installed by @EnableZuulServer. The additional filters in the "proxy" enable routing functionality. If you want a "blank" Zuul, you should use @EnableZuulServer. +
+
+<literal>@EnableZuulServer</literal> Filters +Creates a SimpleRouteLocator that loads route definitions from Spring Boot configuration files. +The following filters are installed (as normal Spring Beans): +Pre filters: + + +ServletDetectionFilter: Detects if the request is through the Spring Dispatcher. Sets boolean with key FilterConstants.IS_DISPATCHER_SERVLET_REQUEST_KEY. + + +FormBodyWrapperFilter: Parses form data and reencodes it for downstream requests. + + +DebugFilter: if the debug request parameter is set, this filter sets RequestContext.setDebugRouting() and RequestContext.setDebugRequest() to true. + + +Route filters: + + +SendForwardFilter: This filter forwards requests using the Servlet RequestDispatcher. The forwarding location is stored in the RequestContext attribute FilterConstants.FORWARD_TO_KEY. This is useful for forwarding to endpoints in the current application. + + +Post filters: + + +SendResponseFilter: Writes responses from proxied requests to the current response. + + +Error filters: + + +SendErrorFilter: Forwards to /error (by default) if RequestContext.getThrowable() is not null. The default forwarding path (/error) can be changed by setting the error.path property. + + +
+
+<literal>@EnableZuulProxy</literal> Filters +Creates a DiscoveryClientRouteLocator that loads route definitions from a DiscoveryClient (like Eureka), as well as from properties. A route is created for each serviceId from the DiscoveryClient. As new services are added, the routes will be refreshed. +In addition to the filters described above, the following filters are installed (as normal Spring Beans): +Pre filters: + + +PreDecorationFilter: This filter determines where and how to route based on the supplied RouteLocator. It also sets various proxy-related headers for downstream requests. + + +Route filters: + + +RibbonRoutingFilter: This filter uses Ribbon, Hystrix and pluggable HTTP clients to send requests. Service ids are found in the RequestContext attribute FilterConstants.SERVICE_ID_KEY. This filter can use different HTTP clients. They are: + + +Apache HttpClient. This is the default client. + + +Squareup OkHttpClient v3. This is enabled by having the com.squareup.okhttp3:okhttp library on the classpath and setting ribbon.okhttp.enabled=true. + + +Netflix Ribbon HTTP client. This is enabled by setting ribbon.restclient.enabled=true. This client has limitations, such as it doesn’t support the PATCH method, but also has built-in retry. + + + + +SimpleHostRoutingFilter: This filter sends requests to predetermined URLs via an Apache HttpClient. URLs are found in RequestContext.getRouteHost(). + + +
+
+Custom Zuul Filter examples +Most of the following "How to Write" examples below are included Sample Zuul Filters project. There are also examples of manipulating the request or response body in that repository. +
+
+How to Write a Pre Filter +Pre filters are used to set up data in the RequestContext for use in filters downstream. The main use case is to set information required for route filters. +public class QueryParamPreFilter extends ZuulFilter { + @Override + public int filterOrder() { + return PRE_DECORATION_FILTER_ORDER - 1; // run before PreDecoration + } + + @Override + public String filterType() { + return PRE_TYPE; + } + + @Override + public boolean shouldFilter() { + RequestContext ctx = RequestContext.getCurrentContext(); + return !ctx.containsKey(FORWARD_TO_KEY) // a filter has already forwarded + && !ctx.containsKey(SERVICE_ID_KEY); // a filter has already determined serviceId + } + @Override + public Object run() { + RequestContext ctx = RequestContext.getCurrentContext(); + HttpServletRequest request = ctx.getRequest(); + if (request.getParameter("foo") != null) { + // put the serviceId in `RequestContext` + ctx.put(SERVICE_ID_KEY, request.getParameter("foo")); + } + return null; + } +} +The filter above populates SERVICE_ID_KEY from the foo request parameter. In reality, it’s not a good idea to do that kind of direct mapping, but the service id should be looked up from the value of foo instead. +Now that SERVICE_ID_KEY is populated, PreDecorationFilter won’t run and RibbonRoutingFilter will. If you wanted to route to a full URL instead, call ctx.setRouteHost(url) instead. +To modify the path that routing filters will forward to, set the REQUEST_URI_KEY. +
+
+How to Write a Route Filter +Route filters are run after pre filters and are used to make requests to other services. Much of the work here is to translate request and response data to and from the client required model. +public class OkHttpRoutingFilter extends ZuulFilter { + @Autowired + private ProxyRequestHelper helper; + + @Override + public String filterType() { + return ROUTE_TYPE; + } + + @Override + public int filterOrder() { + return SIMPLE_HOST_ROUTING_FILTER_ORDER - 1; + } + + @Override + public boolean shouldFilter() { + return RequestContext.getCurrentContext().getRouteHost() != null + && RequestContext.getCurrentContext().sendZuulResponse(); + } + + @Override + public Object run() { + OkHttpClient httpClient = new OkHttpClient.Builder() + // customize + .build(); + + RequestContext context = RequestContext.getCurrentContext(); + HttpServletRequest request = context.getRequest(); + + String method = request.getMethod(); + + String uri = this.helper.buildZuulRequestURI(request); + + Headers.Builder headers = new Headers.Builder(); + Enumeration<String> headerNames = request.getHeaderNames(); + while (headerNames.hasMoreElements()) { + String name = headerNames.nextElement(); + Enumeration<String> values = request.getHeaders(name); + + while (values.hasMoreElements()) { + String value = values.nextElement(); + headers.add(name, value); + } + } + + InputStream inputStream = request.getInputStream(); + + RequestBody requestBody = null; + if (inputStream != null && HttpMethod.permitsRequestBody(method)) { + MediaType mediaType = null; + if (headers.get("Content-Type") != null) { + mediaType = MediaType.parse(headers.get("Content-Type")); + } + requestBody = RequestBody.create(mediaType, StreamUtils.copyToByteArray(inputStream)); + } + + Request.Builder builder = new Request.Builder() + .headers(headers.build()) + .url(uri) + .method(method, requestBody); + + Response response = httpClient.newCall(builder.build()).execute(); + + LinkedMultiValueMap<String, String> responseHeaders = new LinkedMultiValueMap<>(); + + for (Map.Entry<String, List<String>> entry : response.headers().toMultimap().entrySet()) { + responseHeaders.put(entry.getKey(), entry.getValue()); + } + + this.helper.setResponse(response.code(), response.body().byteStream(), + responseHeaders); + context.setRouteHost(null); // prevent SimpleHostRoutingFilter from running + return null; + } +} +The above filter translates Servlet request information into OkHttp3 request information, executes an HTTP request, then translates OkHttp3 reponse information to the Servlet response. WARNING: this filter might have bugs and not function correctly. +
+
+How to Write a Post Filter +Post filters typically manipulate the response. In the filter below, we add a random UUID as the X-Foo header. Other manipulations, such as transforming the response body, are much more complex and compute-intensive. +public class AddResponseHeaderFilter extends ZuulFilter { + @Override + public String filterType() { + return POST_TYPE; + } + + @Override + public int filterOrder() { + return SEND_RESPONSE_FILTER_ORDER - 1; + } + + @Override + public boolean shouldFilter() { + return true; + } + + @Override + public Object run() { + RequestContext context = RequestContext.getCurrentContext(); + HttpServletResponse servletResponse = context.getResponse(); + servletResponse.addHeader("X-Foo", UUID.randomUUID().toString()); + return null; + } +} +
+
+How Zuul Errors Work +If an exception is thrown during any portion of the Zuul filter lifecycle, the error filters are executed. The SendErrorFilter is only run if RequestContext.getThrowable() is not null. It then sets specific javax.servlet.error.* attributes in the request and forwards the request to the Spring Boot error page. +
+
+Zuul Eager Application Context Loading +Zuul internally uses Ribbon for calling the remote url’s and Ribbon clients are by default lazily loaded up by Spring Cloud on first call. +This behavior can be changed for Zuul using the following configuration and will result in the child Ribbon related Application contexts being eagerly loaded up at application startup time. + +application.yml + +zuul: + ribbon: + eager-load: + enabled: true + + +
+
+ + +Polyglot support with Sidecar +Do you have non-jvm languages you want to take advantage of Eureka, Ribbon and +Config Server? The Spring Cloud Netflix Sidecar was inspired by +Netflix Prana. It includes a simple http api +to get all of the instances (ie host and port) for a given service. You can +also proxy service calls through an embedded Zuul proxy which gets its route +entries from Eureka. The Spring Cloud Config Server can be accessed directly +via host lookup or through the Zuul Proxy. The non-jvm app should implement +a health check so the Sidecar can report to eureka if the app is up or down. +To include Sidecar in your project use the dependency with group org.springframework.cloud +and artifact id spring-cloud-netflix-sidecar. +To enable the Sidecar, create a Spring Boot application with @EnableSidecar. +This annotation includes @EnableCircuitBreaker, @EnableDiscoveryClient, +and @EnableZuulProxy. Run the resulting application on the same host as the +non-jvm application. +To configure the side car add sidecar.port and sidecar.health-uri to application.yml. +The sidecar.port property is the port the non-jvm app is listening on. This +is so the Sidecar can properly register the app with Eureka. The sidecar.health-uri +is a uri accessible on the non-jvm app that mimicks a Spring Boot health +indicator. It should return a json document like the following: + +health-uri-document + +{ + "status":"UP" +} + + +Here is an example application.yml for a Sidecar application: + +application.yml + +server: + port: 5678 +spring: + application: + name: sidecar + +sidecar: + port: 8000 + health-uri: http://localhost:8000/health.json + + +The api for the DiscoveryClient.getInstances() method is /hosts/{serviceId}. +Here is an example response for /hosts/customers that returns two instances on +different hosts. This api is accessible to the non-jvm app (if the sidecar is +on port 5678) at http://localhost:5678/hosts/{serviceId}. + +/hosts/customers + +[ + { + "host": "myhost", + "port": 9000, + "uri": "http://myhost:9000", + "serviceId": "CUSTOMERS", + "secure": false + }, + { + "host": "myhost2", + "port": 9000, + "uri": "http://myhost2:9000", + "serviceId": "CUSTOMERS", + "secure": false + } +] + + +The Zuul proxy automatically adds routes for each service known in eureka to +/<serviceId>, so the customers service is available at /customers. The +Non-jvm app can access the customer service via http://localhost:5678/customers +(assuming the sidecar is listening on port 5678). +If the Config Server is registered with Eureka, non-jvm application can access +it via the Zuul proxy. If the serviceId of the ConfigServer is configserver +and the Sidecar is on port 5678, then it can be accessed at +http://localhost:5678/configserver +Non-jvm app can take advantage of the Config Server’s ability to return YAML +documents. For example, a call to https://sidecar.local.spring.io:5678/configserver/default-master.yml +might result in a YAML document like the following +eureka: + client: + serviceUrl: + defaultZone: http://localhost:8761/eureka/ + password: password +info: + description: Spring Cloud Samples + url: https://github.com/spring-cloud-samples + + +RxJava with Spring MVC +Spring Cloud Netflix includes RxJava. +
+RxJava is a Java VM implementation of Reactive Extensions: a library for composing asynchronous and event-based programs by using observable sequences. +
+Spring Cloud Netflix provides support for returning rx.Single objects from Spring MVC Controllers. It also supports using rx.Observable objects for Server-sent events (SSE). This can be very convenient if your internal APIs are already built using RxJava (see for examples). +Here are some examples of using rx.Single: +@RequestMapping(method = RequestMethod.GET, value = "/single") +public Single<String> single() { + return Single.just("single value"); +} + +@RequestMapping(method = RequestMethod.GET, value = "/singleWithResponse") +public ResponseEntity<Single<String>> singleWithResponse() { + return new ResponseEntity<>(Single.just("single value"), + HttpStatus.NOT_FOUND); +} + +@RequestMapping(method = RequestMethod.GET, value = "/singleCreatedWithResponse") +public Single<ResponseEntity<String>> singleOuterWithResponse() { + return Single.just(new ResponseEntity<>("single value", HttpStatus.CREATED)); +} + +@RequestMapping(method = RequestMethod.GET, value = "/throw") +public Single<Object> error() { + return Single.error(new RuntimeException("Unexpected")); +} +If you have an Observable, rather than a single, you can use .toSingle() or .toList().toSingle(). Here are some examples: +@RequestMapping(method = RequestMethod.GET, value = "/single") +public Single<String> single() { + return Observable.just("single value").toSingle(); +} + +@RequestMapping(method = RequestMethod.GET, value = "/multiple") +public Single<List<String>> multiple() { + return Observable.just("multiple", "values").toList().toSingle(); +} + +@RequestMapping(method = RequestMethod.GET, value = "/responseWithObservable") +public ResponseEntity<Single<String>> responseWithObservable() { + + Observable<String> observable = Observable.just("single value"); + HttpHeaders headers = new HttpHeaders(); + headers.setContentType(APPLICATION_JSON_UTF8); + return new ResponseEntity<>(observable.toSingle(), headers, HttpStatus.CREATED); +} + +@RequestMapping(method = RequestMethod.GET, value = "/timeout") +public Observable<String> timeout() { + return Observable.timer(1, TimeUnit.MINUTES).map(new Func1<Long, String>() { + @Override + public String call(Long aLong) { + return "single value"; + } + }); +} +If you have a streaming endpoint and client, SSE could be an option. To convert rx.Observable to a Spring SseEmitter use RxResponse.sse(). Here are some examples: +@RequestMapping(method = RequestMethod.GET, value = "/sse") +public SseEmitter single() { + return RxResponse.sse(Observable.just("single value")); +} + +@RequestMapping(method = RequestMethod.GET, value = "/messages") +public SseEmitter messages() { + return RxResponse.sse(Observable.just("message 1", "message 2", "message 3")); +} + +@RequestMapping(method = RequestMethod.GET, value = "/events") +public SseEmitter event() { + return RxResponse.sse(APPLICATION_JSON_UTF8, + Observable.just(new EventDto("Spring io", getDate(2016, 5, 19)), + new EventDto("SpringOnePlatform", getDate(2016, 8, 1)))); +} + + +Metrics: Spectator, Servo, and Atlas +When used together, Spectator/Servo and Atlas provide a near real-time operational insight platform. +Spectator and Servo are Netflix’s metrics collection libraries. Atlas is a Netflix metrics backend to manage dimensional time series data. +Servo served Netflix for several years and is still usable, but is gradually being phased out in favor of Spectator, which is only designed to work with Java 8. Spring Cloud Netflix provides support for both, but Java 8 based applications are encouraged to use Spectator. +To enable Servo you must set spring.metrics.servo.enabled to true. +
+Dimensional vs. Hierarchical Metrics +Spring Boot Actuator metrics are hierarchical and metrics are separated only by name. These names often follow a naming convention that embeds key/value attribute pairs (dimensions) into the name separated by periods. Consider the following metrics for two endpoints, root and star-star: +{ + "counter.status.200.root": 20, + "counter.status.400.root": 3, + "counter.status.200.star-star": 5, +} +The first metric gives us a normalized count of successful requests against the root endpoint per unit of time. But what if the system had 20 endpoints and you want to get a count of successful requests against all the endpoints? Some hierarchical metrics backends would allow you to specify a wild card such as counter.status.200.* that would read all 20 metrics and aggregate the results. Alternatively, you could provide a HandlerInterceptorAdapter that intercepts and records a metric like counter.status.200.all for all successful requests irrespective of the endpoint, but now you must write 20+1 different metrics. Similarly if you want to know the total number of successful requests for all endpoints in the service, you could specify a wild card such as counter.status.2*.*. +Even in the presence of wildcarding support on a hierarchical metrics backend, naming consistency can be difficult. Specifically the position of these tags in the name string can slip with time, breaking queries. For example, suppose we add an additional dimension to the hierarchical metrics above for HTTP method. Then counter.status.200.root becomes counter.status.200.method.get.root, etc. Our counter.status.200.* suddenly no longer has the same semantic meaning. Furthermore, if the new dimension is not applied uniformly across the codebase, certain queries may become impossible. This can quickly get out of hand. +Netflix metrics are tagged (a.k.a. dimensional). Each metric has a name, but this single named metric can contain multiple statistics and 'tag' key/value pairs that allows more querying flexibility. In fact, the statistics themselves are recorded in a special tag. +Recorded with Netflix Servo or Spectator, a timer for the root endpoint described above contains 4 statistics per status code, where the count statistic is identical to Spring Boot Actuator’s counter. In the event that we have encountered an HTTP 200 and 400 thus far, there will be 8 available data points: +{ + "root(status=200,stastic=count)": 20, + "root(status=200,stastic=max)": 0.7265630630000001, + "root(status=200,stastic=totalOfSquares)": 0.04759702862580789, + "root(status=200,stastic=totalTime)": 0.2093076914666667, + "root(status=400,stastic=count)": 1, + "root(status=400,stastic=max)": 0, + "root(status=400,stastic=totalOfSquares)": 0, + "root(status=400,stastic=totalTime)": 0, +} +
+
+Default Metrics Collection +Without any additional dependencies or configuration, a Spring Cloud based service will autoconfigure a Servo MonitorRegistry and begin collecting metrics on every Spring MVC request. By default, a Servo timer with the name rest will be recorded for each MVC request which is tagged with: + + +HTTP method + + +HTTP status (e.g. 200, 400, 500) + + +URI (or "root" if the URI is empty), sanitized for Atlas + + +The exception class name, if the request handler threw an exception + + +The caller, if a request header with a key matching netflix.metrics.rest.callerHeader is set on the request. There is no default key for netflix.metrics.rest.callerHeader. You must add it to your application properties if you wish to collect caller information. + + +Set the netflix.metrics.rest.metricName property to change the name of the metric from rest to a name you provide. +If Spring AOP is enabled and org.aspectj:aspectjweaver is present on your runtime classpath, Spring Cloud will also collect metrics on every client call made with RestTemplate. A Servo timer with the name of restclient will be recorded for each MVC request which is tagged with: + + +HTTP method + + +HTTP status (e.g. 200, 400, 500), "CLIENT_ERROR" if the response returned null, or "IO_ERROR" if an IOException occurred during the execution of the RestTemplate method + + +URI, sanitized for Atlas + + +Client name + + + +Avoid using hardcoded url parameters within RestTemplate. When targeting dynamic endpoints use URL variables. This will avoid potential "GC Overhead Limit Reached" issues where ServoMonitorCache treats each url as a unique key. + +// recommended +String orderid = "1"; +restTemplate.getForObject("http://testclient/orders/{orderid}", String.class, orderid) + +// avoid +restTemplate.getForObject("http://testclient/orders/1", String.class) +
+
+Metrics Collection: Spectator +To enable Spectator metrics, include a dependency on spring-boot-starter-spectator: + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-netflix-spectator</artifactId> + </dependency> +In Spectator parlance, a meter is a named, typed, and tagged configuration and a metric represents the value of a given meter at a point in time. Spectator meters are created and controlled by a registry, which currently has several different implementations. Spectator provides 4 meter types: counter, timer, gauge, and distribution summary. +Spring Cloud Spectator integration configures an injectable com.netflix.spectator.api.Registry instance for you. Specifically, it configures a ServoRegistry instance in order to unify the collection of REST metrics and the exporting of metrics to the Atlas backend under a single Servo API. Practically, this means that your code may use a mixture of Servo monitors and Spectator meters and both will be scooped up by Spring Boot Actuator MetricReader instances and both will be shipped to the Atlas backend. +
+Spectator Counter +A counter is used to measure the rate at which some event is occurring. +// create a counter with a name and a set of tags +Counter counter = registry.counter("counterName", "tagKey1", "tagValue1", ...); +counter.increment(); // increment when an event occurs +counter.increment(10); // increment by a discrete amount +The counter records a single time-normalized statistic. +
+
+Spectator Timer +A timer is used to measure how long some event is taking. Spring Cloud automatically records timers for Spring MVC requests and conditionally RestTemplate requests, which can later be used to create dashboards for request related metrics like latency: +
+Request Latency + + + + +RequestLatency + +
+// create a timer with a name and a set of tags +Timer timer = registry.timer("timerName", "tagKey1", "tagValue1", ...); + +// execute an operation and time it at the same time +T result = timer.record(() -> fooReturnsT()); + +// alternatively, if you must manually record the time +Long start = System.nanoTime(); +T result = fooReturnsT(); +timer.record(System.nanoTime() - start, TimeUnit.NANOSECONDS); +The timer simultaneously records 4 statistics: count, max, totalOfSquares, and totalTime. The count statistic will always match the single normalized value provided by a counter if you had called increment() once on the counter for each time you recorded a timing, so it is rarely necessary to count and time separately for a single operation. +For long running operations, Spectator provides a special LongTaskTimer. +
+
+Spectator Gauge +Gauges are used to determine some current value like the size of a queue or number of threads in a running state. Since gauges are sampled, they provide no information about how these values fluctuate between samples. +The normal use of a gauge involves registering the gauge once in initialization with an id, a reference to the object to be sampled, and a function to get or compute a numeric value based on the object. The reference to the object is passed in separately and the Spectator registry will keep a weak reference to the object. If the object is garbage collected, then Spectator will automatically drop the registration. See the note in Spectator’s documentation about potential memory leaks if this API is misused. +// the registry will automatically sample this gauge periodically +registry.gauge("gaugeName", pool, Pool::numberOfRunningThreads); + +// manually sample a value in code at periodic intervals -- last resort! +registry.gauge("gaugeName", Arrays.asList("tagKey1", "tagValue1", ...), 1000); +
+
+Spectator Distribution Summaries +A distribution summary is used to track the distribution of events. It is similar to a timer, but more general in that the size does not have to be a period of time. For example, a distribution summary could be used to measure the payload sizes of requests hitting a server. +// the registry will automatically sample this gauge periodically +DistributionSummary ds = registry.distributionSummary("dsName", "tagKey1", "tagValue1", ...); +ds.record(request.sizeInBytes()); +
+
+
+Metrics Collection: Servo + +If your code is compiled on Java 8, please use Spectator instead of Servo as Spectator is destined to replace Servo entirely in the long term. + +In Servo parlance, a monitor is a named, typed, and tagged configuration and a metric represents the value of a given monitor at a point in time. Servo monitors are logically equivalent to Spectator meters. Servo monitors are created and controlled by a MonitorRegistry. In spite of the above warning, Servo does have a wider array of monitor options than Spectator has meters. +Spring Cloud integration configures an injectable com.netflix.servo.MonitorRegistry instance for you. Once you have created the appropriate Monitor type in Servo, the process of recording data is wholly similar to Spectator. +
+Creating Servo Monitors +If you are using the Servo MonitorRegistry instance provided by Spring Cloud (specifically, an instance of DefaultMonitorRegistry), Servo provides convenience classes for retrieving counters and timers. These convenience classes ensure that only one Monitor is registered for each unique combination of name and tags. +To manually create a Monitor type in Servo, especially for the more exotic monitor types for which convenience methods are not provided, instantiate the appropriate type by providing a MonitorConfig instance: +MonitorConfig config = MonitorConfig.builder("timerName").withTag("tagKey1", "tagValue1").build(); + +// somewhere we should cache this Monitor by MonitorConfig +Timer timer = new BasicTimer(config); +monitorRegistry.register(timer); +
+
+
+Metrics Backend: Atlas +Atlas was developed by Netflix to manage dimensional time series data for near real-time operational insight. Atlas features in-memory data storage, allowing it to gather and report very large numbers of metrics, very quickly. +Atlas captures operational intelligence. Whereas business intelligence is data gathered for analyzing trends over time, operational intelligence provides a picture of what is currently happening within a system. +Spring Cloud provides a spring-cloud-starter-netflix-atlas that has all the dependencies you need. Then just annotate your Spring Boot application with @EnableAtlas and provide a location for your running Atlas server with the netflix.atlas.uri property. +
+Global tags +Spring Cloud enables you to add tags to every metric sent to the Atlas backend. Global tags can be used to separate metrics by application name, environment, region, etc. +Each bean implementing AtlasTagProvider will contribute to the global tag list: +@Bean +AtlasTagProvider atlasCommonTags( + @Value("${spring.application.name}") String appName) { + return () -> Collections.singletonMap("app", appName); +} +
+
+Using Atlas +To bootstrap a in-memory standalone Atlas instance: +$ curl -LO https://github.com/Netflix/atlas/releases/download/v1.4.2/atlas-1.4.2-standalone.jar +$ java -jar atlas-1.4.2-standalone.jar + +An Atlas standalone node running on an r3.2xlarge (61GB RAM) can handle roughly 2 million metrics per minute for a given 6 hour window. + +Once running and you have collected a handful of metrics, verify that your setup is correct by listing tags on the Atlas server: +$ curl http://ATLAS/api/v1/tags + +After executing several requests against your service, you can gather some very basic information on the request latency of every request by pasting the following url in your browser: http://ATLAS/api/v1/graph?q=name,rest,:eq,:avg + +The Atlas wiki contains a compilation of sample queries for various scenarios. +Make sure to check out the alerting philosophy and docs on using double exponential smoothing to generate dynamic alert thresholds. +
+
+
+Retrying Failed Requests +Spring Cloud Netflix offers a variety of ways to make HTTP requests. You can use a load balanced +RestTemplate, Ribbon, or Feign. No matter how you choose to your HTTP requests, there is always +a chance the request may fail. When a request fails you may want to have the request retried +automatically. To accomplish this when using Sping Cloud Netflix you need to include +Spring Retry on your application’s classpath. +When Spring Retry is present load balanced RestTemplates, Feign, and Zuul will automatically +retry any failed requests (assuming you configuration allows it to). +
+BackOff Policies +By default no backoff policy is used when retrying requests. If you would like to configure +a backoff policy you will need to create a bean of type LoadBalancedBackOffPolicyFactory +which will be used to create a BackOffPolicy for a given service. +@Configuration +public class MyConfiguration { + @Bean + LoadBalancedBackOffPolicyFactory backOffPolciyFactory() { + return new LoadBalancedBackOffPolicyFactory() { + @Override + public BackOffPolicy createBackOffPolicy(String service) { + return new ExponentialBackOffPolicy(); + } + }; + } +} +
+
+Configuration +Anytime Ribbon is used with Spring Retry you can control the retry functionality by configuring +certain Ribbon properties. The properties you can use are +client.ribbon.MaxAutoRetries, client.ribbon.MaxAutoRetriesNextServer, and +client.ribbon.OkToRetryOnAllOperations. See the Ribbon documentation +for a description of what there properties do. + +Enabling client.ribbon.OkToRetryOnAllOperations includes retring POST requests wich can have a impact +on the server’s resources due to the buffering of the request’s body. + +In addition you may want to retry requests when certain status codes are returned in the +response. You can list the response codes you would like the Ribbon client to retry using the + property clientName.ribbon.retryableStatusCodes. For example +clientName: + ribbon: + retryableStatusCodes: 404,502 +You can also create a bean of type LoadBalancedRetryPolicy and implement the retryableStatusCode +method to determine whether you want to retry a request given the status code. +
+
+Zuul +You can turn off Zuul’s retry functionality by setting zuul.retryable to false. You +can also disable retry functionality on route by route basis by setting +zuul.routes.routename.retryable to false. +
+
+ + +HTTP Clients +Spring Cloud Netflix will automatically create the HTTP client used by Ribbon, Feign, and +Zuul for you. However you can also provide your own HTTP clients customized how you please +yourself. To do this you can either create a bean of type ClosableHttpClient if you +are using the Apache Http Cient, or OkHttpClient if you are using OK HTTP. + +When you create your own HTTP client you are also responsible for implementing +the correct connection management strategies for these clients. Doing this improperly +can result in resource management issues. + + + + +Spring Cloud Stream + +This section goes into more detail about how you can work with Spring Cloud Stream. +It covers topics such as creating and running stream applications. + + +Introducing Spring Cloud Stream +Spring Cloud Stream is a framework for building message-driven microservice applications. +Spring Cloud Stream builds upon Spring Boot to create standalone, production-grade Spring applications, and uses Spring Integration to provide connectivity to message brokers. +It provides opinionated configuration of middleware from several vendors, introducing the concepts of persistent publish-subscribe semantics, consumer groups, and partitions. +You can add the @EnableBinding annotation to your application to get immediate connectivity to a message broker, and you can add @StreamListener to a method to cause it to receive events for stream processing. +The following is a simple sink application which receives external messages. +@SpringBootApplication +@EnableBinding(Sink.class) +public class VoteRecordingSinkApplication { + + public static void main(String[] args) { + SpringApplication.run(VoteRecordingSinkApplication.class, args); + } + + @StreamListener(Sink.INPUT) + public void processVote(Vote vote) { + votingService.recordVote(vote); + } +} +The @EnableBinding annotation takes one or more interfaces as parameters (in this case, the parameter is a single Sink interface). +An interface declares input and/or output channels. +Spring Cloud Stream provides the interfaces Source, Sink, and Processor; you can also define your own interfaces. +The following is the definition of the Sink interface: +public interface Sink { + String INPUT = "input"; + + @Input(Sink.INPUT) + SubscribableChannel input(); +} +The @Input annotation identifies an input channel, through which received messages enter the application; the @Output annotation identifies an output channel, through which published messages leave the application. +The @Input and @Output annotations can take a channel name as a parameter; if a name is not provided, the name of the annotated method will be used. +Spring Cloud Stream will create an implementation of the interface for you. +You can use this in the application by autowiring it, as in the following example of a test case. +@RunWith(SpringJUnit4ClassRunner.class) +@SpringApplicationConfiguration(classes = VoteRecordingSinkApplication.class) +@WebAppConfiguration +@DirtiesContext +public class StreamApplicationTests { + + @Autowired + private Sink sink; + + @Test + public void contextLoads() { + assertNotNull(this.sink.input()); + } +} + + +Main Concepts +Spring Cloud Stream provides a number of abstractions and primitives that simplify the writing of message-driven microservice applications. +This section gives an overview of the following: + + +Spring Cloud Stream’s application model + + +The Binder abstraction + + +Persistent publish-subscribe support + + +Consumer group support + + +Partitioning support + + +A pluggable Binder API + + +
+Application Model +A Spring Cloud Stream application consists of a middleware-neutral core. +The application communicates with the outside world through input and output channels injected into it by Spring Cloud Stream. +Channels are connected to external brokers through middleware-specific Binder implementations. +
+Spring Cloud Stream Application + + + + +SCSt with binder + +
+
+Fat JAR +Spring Cloud Stream applications can be run in standalone mode from your IDE for testing. +To run a Spring Cloud Stream application in production, you can create an executable (or "fat") JAR by using the standard Spring Boot tooling provided for Maven or Gradle. +
+
+
+The Binder Abstraction +Spring Cloud Stream provides Binder implementations for Kafka and Rabbit MQ. +Spring Cloud Stream also includes a TestSupportBinder, which leaves a channel unmodified so that tests can interact with channels directly and reliably assert on what is received. +You can use the extensible API to write your own Binder. +Spring Cloud Stream uses Spring Boot for configuration, and the Binder abstraction makes it possible for a Spring Cloud Stream application to be flexible in how it connects to middleware. +For example, deployers can dynamically choose, at runtime, the destinations (e.g., the Kafka topics or RabbitMQ exchanges) to which channels connect. +Such configuration can be provided through external configuration properties and in any form supported by Spring Boot (including application arguments, environment variables, and application.yml or application.properties files). +In the sink example from the section, setting the application property spring.cloud.stream.bindings.input.destination to raw-sensor-data will cause it to read from the raw-sensor-data Kafka topic, or from a queue bound to the raw-sensor-data RabbitMQ exchange. +Spring Cloud Stream automatically detects and uses a binder found on the classpath. +You can easily use different types of middleware with the same code: just include a different binder at build time. +For more complex use cases, you can also package multiple binders with your application and have it choose the binder, and even whether to use different binders for different channels, at runtime. +
+
+Persistent Publish-Subscribe Support +Communication between applications follows a publish-subscribe model, where data is broadcast through shared topics. +This can be seen in the following figure, which shows a typical deployment for a set of interacting Spring Cloud Stream applications. +
+Spring Cloud Stream Publish-Subscribe + + + + +SCSt sensors + +
+Data reported by sensors to an HTTP endpoint is sent to a common destination named raw-sensor-data. +From the destination, it is independently processed by a microservice application that computes time-windowed averages and by another microservice application that ingests the raw data into HDFS. +In order to process the data, both applications declare the topic as their input at runtime. +The publish-subscribe communication model reduces the complexity of both the producer and the consumer, and allows new applications to be added to the topology without disruption of the existing flow. +For example, downstream from the average-calculating application, you can add an application that calculates the highest temperature values for display and monitoring. +You can then add another application that interprets the same flow of averages for fault detection. +Doing all communication through shared topics rather than point-to-point queues reduces coupling between microservices. +While the concept of publish-subscribe messaging is not new, Spring Cloud Stream takes the extra step of making it an opinionated choice for its application model. +By using native middleware support, Spring Cloud Stream also simplifies use of the publish-subscribe model across different platforms. +
+
+Consumer Groups +While the publish-subscribe model makes it easy to connect applications through shared topics, the ability to scale up by creating multiple instances of a given application is equally important. +When doing this, different instances of an application are placed in a competing consumer relationship, where only one of the instances is expected to handle a given message. +Spring Cloud Stream models this behavior through the concept of a consumer group. +(Spring Cloud Stream consumer groups are similar to and inspired by Kafka consumer groups.) +Each consumer binding can use the spring.cloud.stream.bindings.<channelName>.group property to specify a group name. +For the consumers shown in the following figure, this property would be set as spring.cloud.stream.bindings.<channelName>.group=hdfsWrite or spring.cloud.stream.bindings.<channelName>.group=average. +
+Spring Cloud Stream Consumer Groups + + + + +SCSt groups + +
+All groups which subscribe to a given destination receive a copy of published data, but only one member of each group receives a given message from that destination. +By default, when a group is not specified, Spring Cloud Stream assigns the application to an anonymous and independent single-member consumer group that is in a publish-subscribe relationship with all other consumer groups. +
+Durability +Consistent with the opinionated application model of Spring Cloud Stream, consumer group subscriptions are durable. +That is, a binder implementation ensures that group subscriptions are persistent, and once at least one subscription for a group has been created, the group will receive messages, even if they are sent while all applications in the group are stopped. + +Anonymous subscriptions are non-durable by nature. +For some binder implementations (e.g., RabbitMQ), it is possible to have non-durable group subscriptions. + +In general, it is preferable to always specify a consumer group when binding an application to a given destination. +When scaling up a Spring Cloud Stream application, you must specify a consumer group for each of its input bindings. +This prevents the application’s instances from receiving duplicate messages (unless that behavior is desired, which is unusual). +
+
+
+Partitioning Support +Spring Cloud Stream provides support for partitioning data between multiple instances of a given application. +In a partitioned scenario, the physical communication medium (e.g., the broker topic) is viewed as being structured into multiple partitions. +One or more producer application instances send data to multiple consumer application instances and ensure that data identified by common characteristics are processed by the same consumer instance. +Spring Cloud Stream provides a common abstraction for implementing partitioned processing use cases in a uniform fashion. +Partitioning can thus be used whether the broker itself is naturally partitioned (e.g., Kafka) or not (e.g., RabbitMQ). +
+Spring Cloud Stream Partitioning + + + + +SCSt partitioning + +
+Partitioning is a critical concept in stateful processing, where it is critiical, for either performance or consistency reasons, to ensure that all related data is processed together. +For example, in the time-windowed average calculation example, it is important that all measurements from any given sensor are processed by the same application instance. + +To set up a partitioned processing scenario, you must configure both the data-producing and the data-consuming ends. + +
+ + +Programming Model +This section describes Spring Cloud Stream’s programming model. +Spring Cloud Stream provides a number of predefined annotations for declaring bound input and output channels as well as how to listen to channels. +
+Declaring and Binding Channels +
+Triggering Binding Via <literal>@EnableBinding</literal> +You can turn a Spring application into a Spring Cloud Stream application by applying the @EnableBinding annotation to one of the application’s configuration classes. +The @EnableBinding annotation itself is meta-annotated with @Configuration and triggers the configuration of Spring Cloud Stream infrastructure: +... +@Import(...) +@Configuration +@EnableIntegration +public @interface EnableBinding { + ... + Class<?>[] value() default {}; +} +The @EnableBinding annotation can take as parameters one or more interface classes that contain methods which represent bindable components (typically message channels). + +The @EnableBinding annotation is only required on your Configuration classes, you can provide as many binding interfaces as you need, for instance: @EnableBinding(value={Orders.class, Payment.class}. +Where both Order and Payment interfaces would declare @Input and @Output channels. + +
+
+<literal>@Input</literal> and <literal>@Output</literal> +A Spring Cloud Stream application can have an arbitrary number of input and output channels defined in an interface as @Input and @Output methods: +public interface Barista { + + @Input + SubscribableChannel orders(); + + @Output + MessageChannel hotDrinks(); + + @Output + MessageChannel coldDrinks(); +} +Using this interface as a parameter to @EnableBinding will trigger the creation of three bound channels named orders, hotDrinks, and coldDrinks, respectively. +@EnableBinding(Barista.class) +public class CafeConfiguration { + + ... +} + +In Spring Cloud Stream, the bindable MessageChannel components are the Spring Messaging MessageChannel (for outbound) and its extension SubscribableChannel (for inbound). +Using the same mechanism other bindable components can be supported. +KStream support in Spring Cloud Stream Kafka binder is one such example where KStream is used as inbound/outbound bindable components. +In this documentation, we will continue to refer to MessageChannels as the bindable components. + +
+Customizing Channel Names +Using the @Input and @Output annotations, you can specify a customized channel name for the channel, as shown in the following example: +public interface Barista { + ... + @Input("inboundOrders") + SubscribableChannel orders(); +} +In this example, the created bound channel will be named inboundOrders. +
+
+<literal>Source</literal>, <literal>Sink</literal>, and <literal>Processor</literal> +For easy addressing of the most common use cases, which involve either an input channel, an output channel, or both, Spring Cloud Stream provides three predefined interfaces out of the box. +Source can be used for an application which has a single outbound channel. +public interface Source { + + String OUTPUT = "output"; + + @Output(Source.OUTPUT) + MessageChannel output(); + +} +Sink can be used for an application which has a single inbound channel. +public interface Sink { + + String INPUT = "input"; + + @Input(Sink.INPUT) + SubscribableChannel input(); + +} +Processor can be used for an application which has both an inbound channel and an outbound channel. +public interface Processor extends Source, Sink { +} +Spring Cloud Stream provides no special handling for any of these interfaces; they are only provided out of the box. +
+
+
+Accessing Bound Channels +
+Injecting the Bound Interfaces +For each bound interface, Spring Cloud Stream will generate a bean that implements the interface. +Invoking a @Input-annotated or @Output-annotated method of one of these beans will return the relevant bound channel. +The bean in the following example sends a message on the output channel when its hello method is invoked. +It invokes output() on the injected Source bean to retrieve the target channel. +@Component +public class SendingBean { + + private Source source; + + @Autowired + public SendingBean(Source source) { + this.source = source; + } + + public void sayHello(String name) { + source.output().send(MessageBuilder.withPayload(name).build()); + } +} +
+
+Injecting Channels Directly +Bound channels can be also injected directly: +@Component +public class SendingBean { + + private MessageChannel output; + + @Autowired + public SendingBean(MessageChannel output) { + this.output = output; + } + + public void sayHello(String name) { + output.send(MessageBuilder.withPayload(name).build()); + } +} +If the name of the channel is customized on the declaring annotation, that name should be used instead of the method name. +Given the following declaration: +public interface CustomSource { + ... + @Output("customOutput") + MessageChannel output(); +} +The channel will be injected as shown in the following example: +@Component +public class SendingBean { + + private MessageChannel output; + + @Autowired + public SendingBean(@Qualifier("customOutput") MessageChannel output) { + this.output = output; + } + + public void sayHello(String name) { + this.output.send(MessageBuilder.withPayload(name).build()); + } +} +
+
+
+Producing and Consuming Messages +You can write a Spring Cloud Stream application using either Spring Integration annotations or Spring Cloud Stream’s @StreamListener annotation. +The @StreamListener annotation is modeled after other Spring Messaging annotations (such as @MessageMapping, @JmsListener, @RabbitListener, etc.) but adds content type management and type coercion features. +
+Native Spring Integration Support +Because Spring Cloud Stream is based on Spring Integration, Stream completely inherits Integration’s foundation and infrastructure as well as the component itself. +For example, you can attach the output channel of a Source to a MessageSource: +@EnableBinding(Source.class) +public class TimerSource { + + @Value("${format}") + private String format; + + @Bean + @InboundChannelAdapter(value = Source.OUTPUT, poller = @Poller(fixedDelay = "${fixedDelay}", maxMessagesPerPoll = "1")) + public MessageSource<String> timerMessageSource() { + return () -> new GenericMessage<>(new SimpleDateFormat(format).format(new Date())); + } +} +Or you can use a processor’s channels in a transformer: +@EnableBinding(Processor.class) +public class TransformProcessor { + @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT) + public Object transform(String message) { + return message.toUpperCase(); + } +} + +It’s important to understant that when you consume from the same binding using @StreamListener a pubsub model is used, where each method annotated with @StreamListener receives it’s own copy of the message, each one has its own consumer group. +However, if you share a bindable channel as an input for @Aggregator, @Transformer or @ServiceActivator, those will consume in a competing model, no individual consumer group is created for each subscription. + +
+
+Spring Integration Error Channel Support +Spring Cloud Stream supports publishing error messages received by the Spring Integration global +error channel. Error messages sent to the errorChannel can be published to a specific destination +at the broker by configuring a binding for the outbound target named error. For example, to +publish error messages to a broker destination named "myErrors", provide the following property: +spring.cloud.stream.bindings.error.destination=myErrors. +
+
+Message Channel Binders and Error Channels +Starting with version 1.3, some MessageChannel - based binders publish errors to a discrete error channel for each destination. +In addition, these error channels are bridged to the global Spring Integration errorChannel mentioned above. +You can therefore consume errors for specific destinations and/or for all destinations, using a standard Spring Integration flow (IntegrationFlow, @ServiceActivator, etc). +On the consumer side, the listener thread catches any exceptions and forwards an ErrorMessage to the destination’s error channel. +The payload of the message is a MessagingException with the normal failedMessage and cause properties. +Usually, the raw data received from the broker is included in a header. +For binders that support (and are configured with) a dead letter destination; a MessagePublishingErrorHandler is subscribed to the channel, and the raw data is forwarded to the dead letter destination. +On the producer side; for binders that support some kind of async result after publishing messages (e.g. RabbitMQ, Kafka), you can enable an error channel by setting the …​producer.errorChannelEnabled to true. +The payload of the ErrorMessage depends on the binder implementation but will be a MessagingException with the normal failedMessage property, as well as additional properties about the failure. +Refer to the binder documentation for complete details. +
+
+Using @StreamListener for Automatic Content Type Handling +Complementary to its Spring Integration support, Spring Cloud Stream provides its own @StreamListener annotation, modeled after other Spring Messaging annotations (e.g. @MessageMapping, @JmsListener, @RabbitListener, etc.). +The @StreamListener annotation provides a simpler model for handling inbound messages, especially when dealing with use cases that involve content type management and type coercion. +Spring Cloud Stream provides an extensible MessageConverter mechanism for handling data conversion by bound channels and for, in this case, dispatching to methods annotated with @StreamListener. +The following is an example of an application which processes external Vote events: +@EnableBinding(Sink.class) +public class VoteHandler { + + @Autowired + VotingService votingService; + + @StreamListener(Sink.INPUT) + public void handle(Vote vote) { + votingService.record(vote); + } +} +The distinction between @StreamListener and a Spring Integration @ServiceActivator is seen when considering an inbound Message that has a String payload and a contentType header of application/json. +In the case of @StreamListener, the MessageConverter mechanism will use the contentType header to parse the String payload into a Vote object. +As with other Spring Messaging methods, method arguments can be annotated with @Payload, @Headers and @Header. + +For methods which return data, you must use the @SendTo annotation to specify the output binding destination for data returned by the method: +@EnableBinding(Processor.class) +public class TransformProcessor { + + @Autowired + VotingService votingService; + + @StreamListener(Processor.INPUT) + @SendTo(Processor.OUTPUT) + public VoteResult handle(Vote vote) { + return votingService.record(vote); + } +} + +
+
+Using @StreamListener for dispatching messages to multiple methods +Since version 1.2, Spring Cloud Stream supports dispatching messages to multiple @StreamListener methods registered on an input channel, based on a condition. +In order to be eligible to support conditional dispatching, a method must satisfy the follow conditions: + + +it must not return a value + + +it must be an individual message handling method (reactive API methods are not supported) + + +The condition is specified via a SpEL expression in the condition attribute of the annotation and is evaluated for each message. +All the handlers that match the condition will be invoked in the same thread and no assumption must be made about the order in which the invocations take place. +An example of using @StreamListener with dispatching conditions can be seen below. +In this example, all the messages bearing a header type with the value foo will be dispatched to the receiveFoo method, and all the messages bearing a header type with the value bar will be dispatched to the receiveBar method. +@EnableBinding(Sink.class) +@EnableAutoConfiguration +public static class TestPojoWithAnnotatedArguments { + + @StreamListener(target = Sink.INPUT, condition = "headers['type']=='foo'") + public void receiveFoo(@Payload FooPojo fooPojo) { + // handle the message + } + + @StreamListener(target = Sink.INPUT, condition = "headers['type']=='bar'") + public void receiveBar(@Payload BarPojo barPojo) { + // handle the message + } +} + +Dispatching via @StreamListener conditions is only supported for handlers of individual messages, and not for reactive programming support (described below). + +
+
+
+Reactive Programming Support +Spring Cloud Stream also supports the use of reactive APIs where incoming and outgoing data is handled as continuous data flows. +Support for reactive APIs is available via the spring-cloud-stream-reactive, which needs to be added explicitly to your project. +The programming model with reactive APIs is declarative, where instead of specifying how each individual message should be handled, you can use operators that describe functional transformations from inbound to outbound data flows. +Spring Cloud Stream supports the following reactive APIs: + + +Reactor + + +RxJava 1.x + + +In the future, it is intended to support a more generic model based on Reactive Streams. +The reactive programming model is also using the @StreamListener annotation for setting up reactive handlers. The differences are that: + + +the @StreamListener annotation must not specify an input or output, as they are provided as arguments and return values from the method; + + +the arguments of the method must be annotated with @Input and @Output indicating which input or output will the incoming and respectively outgoing data flows connect to; + + +the return value of the method, if any, will be annotated with @Output, indicating the input where data shall be sent. + + + +Reactive programming support requires Java 1.8. + + +As of Spring Cloud Stream 1.1.1 and later (starting with release train Brooklyn.SR2), reactive programming support requires the use of Reactor 3.0.4.RELEASE and higher. +Earlier Reactor versions (including 3.0.1.RELEASE, 3.0.2.RELEASE and 3.0.3.RELEASE) are not supported. +spring-cloud-stream-reactive will transitively retrieve the proper version, but it is possible for the project structure to manage the version of the io.projectreactor:reactor-core to an earlier release, especially when using Maven. +This is the case for projects generated via Spring Initializr with Spring Boot 1.x, which will override the Reactor version to 2.0.8.RELEASE. +In such cases you must ensure that the proper version of the artifact is released. +This can be simply achieved by adding a direct dependency on io.projectreactor:reactor-core with a version of 3.0.4.RELEASE or later to your project. + + +The use of term reactive is currently referring to the reactive APIs being used and not to the execution model being reactive (i.e. the bound endpoints are still using a 'push' rather than 'pull' model). While some backpressure support is provided by the use of Reactor, we do intend on the long run to support entirely reactive pipelines by the use of native reactive clients for the connected middleware. + +
+Reactor-based handlers +A Reactor based handler can have the following argument types: + + +For arguments annotated with @Input, it supports the Reactor type Flux. +The parameterization of the inbound Flux follows the same rules as in the case of individual message handling: it can be the entire Message, a POJO which can be the Message payload, or a POJO which is the result of a transformation based on the Message content-type header. Multiple inputs are provided; + + +For arguments annotated with Output, it supports the type FluxSender which connects a Flux produced by the method with an output. Generally speaking, specifying outputs as arguments is only recommended when the method can have multiple outputs; + + +A Reactor based handler supports a return type of Flux, case in which it must be annotated with @Output. We recommend using the return value of the method when a single output flux is available. +Here is an example of a simple Reactor-based Processor. +@EnableBinding(Processor.class) +@EnableAutoConfiguration +public static class UppercaseTransformer { + + @StreamListener + @Output(Processor.OUTPUT) + public Flux<String> receive(@Input(Processor.INPUT) Flux<String> input) { + return input.map(s -> s.toUpperCase()); + } +} +The same processor using output arguments looks like this: +@EnableBinding(Processor.class) +@EnableAutoConfiguration +public static class UppercaseTransformer { + + @StreamListener + public void receive(@Input(Processor.INPUT) Flux<String> input, + @Output(Processor.OUTPUT) FluxSender output) { + output.send(input.map(s -> s.toUpperCase())); + } +} +
+
+RxJava 1.x support +RxJava 1.x handlers follow the same rules as Reactor-based one, but will use Observable and ObservableSender arguments and return types. +So the first example above will become: +@EnableBinding(Processor.class) +@EnableAutoConfiguration +public static class UppercaseTransformer { + + @StreamListener + @Output(Processor.OUTPUT) + public Observable<String> receive(@Input(Processor.INPUT) Observable<String> input) { + return input.map(s -> s.toUpperCase()); + } +} +The second example above will become: +@EnableBinding(Processor.class) +@EnableAutoConfiguration +public static class UppercaseTransformer { + + @StreamListener + public void receive(@Input(Processor.INPUT) Observable<String> input, + @Output(Processor.OUTPUT) ObservableSender output) { + output.send(input.map(s -> s.toUpperCase())); + } +} +
+
+Reactive Sources +Spring Cloud Stream reactive support also provides the ability for creating reactive sources through the StreamEmitter annotation. +Using StreamEmitter annotation, a regular source may be converted to a reactive one. +StreamEmitter is a method level annotation that marks a method to be an emitter to outputs declared via EnableBinding. +It is not allowed to use the Input annotation along with StreamEmitter, as the methods marked with this annotation are not listening from any input, rather generating to an output. +Following the same programming model used in StreamListener, StreamEmitter also allows flexible ways of using the Output annotation depending on whether the method has any arguments, return type etc. +Here are some examples of using StreamEmitter in various styles. +The following example will emit the "Hello World" message every millisecond and publish to a Flux. +In this case, the resulting messages in Flux will be sent to the output channel of the Source. +@EnableBinding(Source.class) +@EnableAutoConfiguration +public static class HelloWorldEmitter { + + @StreamEmitter + @Output(Source.OUTPUT) + public Flux<String> emit() { + return Flux.intervalMillis(1) + .map(l -> "Hello World"); + } +} +Following is another flavor of the same sample as above. +Instead of returning a Flux, this method uses a FluxSender to programmatically send Flux from a source. +@EnableBinding(Source.class) +@EnableAutoConfiguration +public static class HelloWorldEmitter { + + @StreamEmitter + @Output(Source.OUTPUT) + public void emit(FluxSender output) { + output.send(Flux.intervalMillis(1) + .map(l -> "Hello World")); + } +} +Following is exactly same as the above snippet in functionality and style. +However, instead of using an explicit Output annotation at the method level, it is used as the method parameter level. +@EnableBinding(Source.class) +@EnableAutoConfiguration +public static class HelloWorldEmitter { + + @StreamEmitter + public void emit(@Output(Source.OUTPUT) FluxSender output) { + output.send(Flux.intervalMillis(1) + .map(l -> "Hello World")); + } +} +Here is yet another flavor of writing reacting sources using the Reactive Streams Publisher API and the support for it in the Spring Integration Java DSL. +The Publisher is still using Reactor Flux under the hood, but from an application perspective, that is transparent to the user and only needs Reactive Streams and Java DSL for Spring Integration. +@EnableBinding(Source.class) +@EnableAutoConfiguration +public static class HelloWorldEmitter { + + @StreamEmitter + @Output(Source.OUTPUT) + @Bean + public Publisher<Message<String>> emit() { + return IntegrationFlows.from(() -> + new GenericMessage<>("Hello World"), + e -> e.poller(p -> p.fixedDelay(1))) + .toReactivePublisher(); + } +} +
+
+
+Aggregation +Spring Cloud Stream provides support for aggregating multiple applications together, connecting their input and output channels directly and avoiding the additional cost of exchanging messages via a broker. +As of version 1.0 of Spring Cloud Stream, aggregation is supported only for the following types of applications: + + +sources - applications with a single output channel named output, typically having a single binding of the type org.springframework.cloud.stream.messaging.Source + + +sinks - applications with a single input channel named input, typically having a single binding of the type org.springframework.cloud.stream.messaging.Sink + + +processors - applications with a single input channel named input and a single output channel named output, typically having a single binding of the type org.springframework.cloud.stream.messaging.Processor. + + +They can be aggregated together by creating a sequence of interconnected applications, in which the output channel of an element in the sequence is connected to the input channel of the next element, if it exists. +A sequence can start with either a source or a processor, it can contain an arbitrary number of processors and must end with either a processor or a sink. +Depending on the nature of the starting and ending element, the sequence may have one or more bindable channels, as follows: + + +if the sequence starts with a source and ends with a sink, all communication between the applications is direct and no channels will be bound + + +if the sequence starts with a processor, then its input channel will become the input channel of the aggregate and will be bound accordingly + + +if the sequence ends with a processor, then its output channel will become the output channel of the aggregate and will be bound accordingly + + +Aggregation is performed using the AggregateApplicationBuilder utility class, as in the following example. +Let’s consider a project in which we have source, processor and a sink, which may be defined in the project, or may be contained in one of the project’s dependencies. + +Each component (source, sink or processor) in an aggregate application must be provided in a separate package if the configuration classes use @SpringBootApplication. +This is required to avoid cross-talk between applications, due to the classpath scanning performed by @SpringBootApplication on the configuration classes inside the same package. +In the example below, it can be seen that the Source, Processor and Sink application classes are grouped in separate packages. +A possible alternative is to provide the source, sink or processor configuration in a separate @Configuration class, avoid the use of @SpringBootApplication/@ComponentScan and use those for aggregation. + +package com.app.mysink; + +@SpringBootApplication +@EnableBinding(Sink.class) +public class SinkApplication { + + private static Logger logger = LoggerFactory.getLogger(SinkApplication.class); + + @ServiceActivator(inputChannel=Sink.INPUT) + public void loggerSink(Object payload) { + logger.info("Received: " + payload); + } +} +package com.app.myprocessor; + +// Imports omitted + +@SpringBootApplication +@EnableBinding(Processor.class) +public class ProcessorApplication { + + @Transformer + public String loggerSink(String payload) { + return payload.toUpperCase(); + } +} +package com.app.mysource; + +// Imports omitted + +@SpringBootApplication +@EnableBinding(Source.class) +public class SourceApplication { + + @InboundChannelAdapter(value = Source.OUTPUT) + public String timerMessageSource() { + return new SimpleDateFormat().format(new Date()); + } +} +Each configuration can be used for running a separate component, but in this case they can be aggregated together as follows: +package com.app; + +// Imports omitted + +@SpringBootApplication +public class SampleAggregateApplication { + + public static void main(String[] args) { + new AggregateApplicationBuilder() + .from(SourceApplication.class).args("--fixedDelay=5000") + .via(ProcessorApplication.class) + .to(SinkApplication.class).args("--debug=true").run(args); + } +} +The starting component of the sequence is provided as argument to the from() method. +The ending component of the sequence is provided as argument to the to() method. +Intermediate processors are provided as argument to the via() method. +Multiple processors of the same type can be chained together (e.g. for pipelining transformations with different configurations). +For each component, the builder can provide runtime arguments for Spring Boot configuration. +
+Configuring aggregate application +Spring Cloud Stream supports passing properties for the individual applications inside the aggregate application using 'namespace' as prefix. +The namespace can be set for applications as follows: +@SpringBootApplication +public class SampleAggregateApplication { + + public static void main(String[] args) { + new AggregateApplicationBuilder() + .from(SourceApplication.class).namespace("source").args("--fixedDelay=5000") + .via(ProcessorApplication.class).namespace("processor1") + .to(SinkApplication.class).namespace("sink").args("--debug=true").run(args); + } +} +Once the 'namespace' is set for the individual applications, the application properties with the namespace as prefix can be passed to the aggregate application using any supported property source (commandline, environment properties etc.,) +For instance, to override the default fixedDelay and debug properties of 'source' and 'sink' applications: +java -jar target/MyAggregateApplication-0.0.1-SNAPSHOT.jar --source.fixedDelay=10000 --sink.debug=false +
+
+Configuring binding service properties for non self contained aggregate application +The non self-contained aggregate application is bound to external broker via either or both the inbound/outbound components (typically, message channels) of the aggregate application while the applications inside the aggregate application are directly bound. +For example: a source application’s output and a processor application’s input are directly bound while the processor’s output channel is bound to an external destination at the broker. +When passing the binding service properties for non-self contained aggregate application, it is required to pass the binding service properties to the aggregate application instead of setting them as 'args' to individual child application. +For instance, +@SpringBootApplication +public class SampleAggregateApplication { + + public static void main(String[] args) { + new AggregateApplicationBuilder() + .from(SourceApplication.class).namespace("source").args("--fixedDelay=5000") + .via(ProcessorApplication.class).namespace("processor1").args("--debug=true").run(args); + } +} +The binding properties like --spring.cloud.stream.bindings.output.destination=processor-output need to be specified as one of the external configuration properties (cmdline arg etc.,). +
+
+
+ + +Binders +Spring Cloud Stream provides a Binder abstraction for use in connecting to physical destinations at the external middleware. +This section provides information about the main concepts behind the Binder SPI, its main components, and implementation-specific details. +
+Producers and Consumers +
+Producers and Consumers + + + + +producers consumers + +
+A producer is any component that sends messages to a channel. +The channel can be bound to an external message broker via a Binder implementation for that broker. +When invoking the bindProducer() method, the first parameter is the name of the destination within the broker, the second parameter is the local channel instance to which the producer will send messages, and the third parameter contains properties (such as a partition key expression) to be used within the adapter that is created for that channel. +A consumer is any component that receives messages from a channel. +As with a producer, the consumer’s channel can be bound to an external message broker. +When invoking the bindConsumer() method, the first parameter is the destination name, and a second parameter provides the name of a logical group of consumers. +Each group that is represented by consumer bindings for a given destination receives a copy of each message that a producer sends to that destination (i.e., publish-subscribe semantics). +If there are multiple consumer instances bound using the same group name, then messages will be load-balanced across those consumer instances so that each message sent by a producer is consumed by only a single consumer instance within each group (i.e., queueing semantics). +
+
+Binder SPI +The Binder SPI consists of a number of interfaces, out-of-the box utility classes and discovery strategies that provide a pluggable mechanism for connecting to external middleware. +The key point of the SPI is the Binder interface which is a strategy for connecting inputs and outputs to external middleware. +public interface Binder<T, C extends ConsumerProperties, P extends ProducerProperties> { + Binding<T> bindConsumer(String name, String group, T inboundBindTarget, C consumerProperties); + + Binding<T> bindProducer(String name, T outboundBindTarget, P producerProperties); +} +The interface is parameterized, offering a number of extension points: + + +input and output bind targets - as of version 1.0, only MessageChannel is supported, but this is intended to be used as an extension point in the future; + + +extended consumer and producer properties - allowing specific Binder implementations to add supplemental properties which can be supported in a type-safe manner. + + +A typical binder implementation consists of the following + + +a class that implements the Binder interface; + + +a Spring @Configuration class that creates a bean of the type above along with the middleware connection infrastructure; + + +a META-INF/spring.binders file found on the classpath containing one or more binder definitions, e.g. + + +kafka:\ +org.springframework.cloud.stream.binder.kafka.config.KafkaBinderConfiguration +
+
+Binder Detection +Spring Cloud Stream relies on implementations of the Binder SPI to perform the task of connecting channels to message brokers. +Each Binder implementation typically connects to one type of messaging system. +
+Classpath Detection +By default, Spring Cloud Stream relies on Spring Boot’s auto-configuration to configure the binding process. +If a single Binder implementation is found on the classpath, Spring Cloud Stream will use it automatically. +For example, a Spring Cloud Stream project that aims to bind only to RabbitMQ can simply add the following dependency: +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-binder-rabbit</artifactId> +</dependency> +For the specific maven coordinates of other binder dependencies, please refer to the documentation of that binder implementation. +
+
+
+Multiple Binders on the Classpath +When multiple binders are present on the classpath, the application must indicate which binder is to be used for each channel binding. +Each binder configuration contains a META-INF/spring.binders, which is a simple properties file: +rabbit:\ +org.springframework.cloud.stream.binder.rabbit.config.RabbitServiceAutoConfiguration +Similar files exist for the other provided binder implementations (e.g., Kafka), and custom binder implementations are expected to provide them, as well. +The key represents an identifying name for the binder implementation, whereas the value is a comma-separated list of configuration classes that each contain one and only one bean definition of type org.springframework.cloud.stream.binder.Binder. +Binder selection can either be performed globally, using the spring.cloud.stream.defaultBinder property (e.g., spring.cloud.stream.defaultBinder=rabbit) or individually, by configuring the binder on each channel binding. +For instance, a processor application (that has channels with the names input and output for read/write respectively) which reads from Kafka and writes to RabbitMQ can specify the following configuration: +spring.cloud.stream.bindings.input.binder=kafka +spring.cloud.stream.bindings.output.binder=rabbit +
+
+Connecting to Multiple Systems +By default, binders share the application’s Spring Boot auto-configuration, so that one instance of each binder found on the classpath will be created. +If your application should connect to more than one broker of the same type, you can specify multiple binder configurations, each with different environment settings. + +Turning on explicit binder configuration will disable the default binder configuration process altogether. +If you do this, all binders in use must be included in the configuration. +Frameworks that intend to use Spring Cloud Stream transparently may create binder configurations that can be referenced by name, but will not affect the default binder configuration. +In order to do so, a binder configuration may have its defaultCandidate flag set to false, e.g. spring.cloud.stream.binders.<configurationName>.defaultCandidate=false. +This denotes a configuration that will exist independently of the default binder configuration process. + +For example, this is the typical configuration for a processor application which connects to two RabbitMQ broker instances: +spring: + cloud: + stream: + bindings: + input: + destination: foo + binder: rabbit1 + output: + destination: bar + binder: rabbit2 + binders: + rabbit1: + type: rabbit + environment: + spring: + rabbitmq: + host: <host1> + rabbit2: + type: rabbit + environment: + spring: + rabbitmq: + host: <host2> +
+
+Binder configuration properties +The following properties are available when creating custom binder configurations. +They must be prefixed with spring.cloud.stream.binders.<configurationName>. + + +type + + The binder type. +It typically references one of the binders found on the classpath, in particular a key in a META-INF/spring.binders file. +By default, it has the same value as the configuration name. + + + +inheritEnvironment + +Whether the configuration will inherit the environment of the application itself. +Default true. + + + +environment + + Root for a set of properties that can be used to customize the environment of the binder. +When this is configured, the context in which the binder is being created is not a child of the application context. +This allows for complete separation between the binder components and the application components. +Default empty. + + + +defaultCandidate + + Whether the binder configuration is a candidate for being considered a default binder, or can be used only when explicitly referenced. +This allows adding binder configurations without interfering with the default processing. +Default true. + + + +
+ + +Configuration Options +Spring Cloud Stream supports general configuration options as well as configuration for bindings and binders. +Some binders allow additional binding properties to support middleware-specific features. +Configuration options can be provided to Spring Cloud Stream applications via any mechanism supported by Spring Boot. +This includes application arguments, environment variables, and YAML or .properties files. +
+Spring Cloud Stream Properties + + +spring.cloud.stream.instanceCount + + The number of deployed instances of an application. +Must be set for partitioning and if using Kafka. +Default: 1. + + + +spring.cloud.stream.instanceIndex + + The instance index of the application: a number from 0 to instanceCount-1. +Used for partitioning and with Kafka. +Automatically set in Cloud Foundry to match the application’s instance index. + + + +spring.cloud.stream.dynamicDestinations + + A list of destinations that can be bound dynamically (for example, in a dynamic routing scenario). +If set, only listed destinations can be bound. +Default: empty (allowing any destination to be bound). + + + +spring.cloud.stream.defaultBinder + + The default binder to use, if multiple binders are configured. +See Multiple Binders on the Classpath. +Default: empty. + + + +spring.cloud.stream.overrideCloudConnectors + + This property is only applicable when the cloud profile is active and Spring Cloud Connectors are provided with the application. +If the property is false (the default), the binder will detect a suitable bound service (e.g. a RabbitMQ service bound in Cloud Foundry for the RabbitMQ binder) and will use it for creating connections (usually via Spring Cloud Connectors). +When set to true, this property instructs binders to completely ignore the bound services and rely on Spring Boot properties (e.g. relying on the spring.rabbitmq.* properties provided in the environment for the RabbitMQ binder). +The typical usage of this property is to be nested in a customized environment when connecting to multiple systems. +Default: false. + + + +
+
+Binding Properties +Binding properties are supplied using the format spring.cloud.stream.bindings.<channelName>.<property>=<value>. +The <channelName> represents the name of the channel being configured (e.g., output for a Source). +To avoid repetition, Spring Cloud Stream supports setting values for all channels, in the format spring.cloud.stream.default.<property>=<value>. +In what follows, we indicate where we have omitted the spring.cloud.stream.bindings.<channelName>. prefix and focus just on the property name, with the understanding that the prefix will be included at runtime. +
+Properties for Use of Spring Cloud Stream +The following binding properties are available for both input and output bindings and must be prefixed with spring.cloud.stream.bindings.<channelName>., e.g. spring.cloud.stream.bindings.input.destination=ticktock. +Default values can be set by using the prefix spring.cloud.stream.default, e.g. spring.cloud.stream.default.contentType=application/json. + + +destination + +The target destination of a channel on the bound middleware (e.g., the RabbitMQ exchange or Kafka topic). +If the channel is bound as a consumer, it could be bound to multiple destinations and the destination names can be specified as comma separated String values. +If not set, the channel name is used instead. +The default value of this property cannot be overridden. + + + +group + + The consumer group of the channel. +Applies only to inbound bindings. +See Consumer Groups. +Default: null (indicating an anonymous consumer). + + + +contentType + +The content type of the channel. +Default: null (so that no type coercion is performed). + + + +binder + + The binder used by this binding. +See for details. +Default: null (the default binder will be used, if one exists). + + + +
+
+Consumer properties +The following binding properties are available for input bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.consumer., e.g. spring.cloud.stream.bindings.input.consumer.concurrency=3. +Default values can be set by using the prefix spring.cloud.stream.default.consumer, e.g. spring.cloud.stream.default.consumer.headerMode=raw. + + +concurrency + +The concurrency of the inbound consumer. +Default: 1. + + + +partitioned + +Whether the consumer receives data from a partitioned producer. +Default: false. + + + +headerMode + + When set to raw, disables header parsing on input. +Effective only for messaging middleware that does not support message headers natively and requires header embedding. +Useful when inbound data is coming from outside Spring Cloud Stream applications. +Default: embeddedHeaders. + + + +maxAttempts + +If processing fails, the number of attempts to process the message (including the first). +Set to 1 to disable retry. +Default: 3. + + + +backOffInitialInterval + +The backoff initial interval on retry. +Default: 1000. + + + +backOffMaxInterval + +The maximum backoff interval. +Default: 10000. + + + +backOffMultiplier + +The backoff multiplier. +Default: 2.0. + + + +instanceIndex + + When set to a value greater than equal to zero, allows customizing the instance index of this consumer (if different from spring.cloud.stream.instanceIndex). +When set to a negative value, it will default to spring.cloud.stream.instanceIndex. +Default: -1. + + + +instanceCount + + When set to a value greater than equal to zero, allows customizing the instance count of this consumer (if different from spring.cloud.stream.instanceCount). +When set to a negative value, it will default to spring.cloud.stream.instanceCount. +Default: -1. + + + +
+
+Producer Properties +The following binding properties are available for output bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.producer., e.g. spring.cloud.stream.bindings.input.producer.partitionKeyExpression=payload.id. +Default values can be set by using the prefix spring.cloud.stream.default.producer, e.g. spring.cloud.stream.default.producer.partitionKeyExpression=payload.id. + + +partitionKeyExpression + + A SpEL expression that determines how to partition outbound data. +If set, or if partitionKeyExtractorClass is set, outbound data on this channel will be partitioned, and partitionCount must be set to a value greater than 1 to be effective. +The two options are mutually exclusive. +See . +Default: null. + + + +partitionKeyExtractorClass + + A PartitionKeyExtractorStrategy implementation. +If set, or if partitionKeyExpression is set, outbound data on this channel will be partitioned, and partitionCount must be set to a value greater than 1 to be effective. +The two options are mutually exclusive. +See . +Default: null. + + + +partitionSelectorClass + + A PartitionSelectorStrategy implementation. +Mutually exclusive with partitionSelectorExpression. +If neither is set, the partition will be selected as the hashCode(key) % partitionCount, where key is computed via either partitionKeyExpression or partitionKeyExtractorClass. +Default: null. + + + +partitionSelectorExpression + + A SpEL expression for customizing partition selection. +Mutually exclusive with partitionSelectorClass. +If neither is set, the partition will be selected as the hashCode(key) % partitionCount, where key is computed via either partitionKeyExpression or partitionKeyExtractorClass. +Default: null. + + + +partitionCount + + The number of target partitions for the data, if partitioning is enabled. +Must be + set to a value greater than 1 if the producer is partitioned. +On Kafka, interpreted as a + hint; the larger of this and the partition count of the target topic is used instead. +Default: 1. + + + +requiredGroups + +A comma-separated list of groups to which the producer must ensure message delivery even if they start after it has been created (e.g., by pre-creating durable queues in RabbitMQ). + + + +headerMode + + When set to raw, disables header embedding on output. +Effective only for messaging middleware that does not support message headers natively and requires header embedding. +Useful when producing data for non-Spring Cloud Stream applications. +Default: embeddedHeaders. + + + +useNativeEncoding + + When set to true, the outbound message is serialized directly by client library, which must be configured correspondingly (e.g. setting an appropriate Kafka producer value serializer). +When this configuration is being used, the outbound message marshalling is not based on the contentType of the binding. +When native encoding is used, it is the responsibility of the consumer to use appropriate decoder (ex: Kafka consumer value de-serializer) to deserialize the inbound message. +Also, when native encoding/decoding is used the headerMode property is ignored and headers will not be embedded into the message. +Default: false. + + + +errorChannelEnabled + +When set to true, if the binder supports async send results; send failures will be sent to an error channel for the destination. +See for more information. +Default: false. + + + +
+
+
+Using dynamically bound destinations +Besides the channels defined via @EnableBinding, Spring Cloud Stream allows applications to send messages to dynamically bound destinations. +This is useful, for example, when the target destination needs to be determined at runtime. +Applications can do so by using the BinderAwareChannelResolver bean, registered automatically by the @EnableBinding annotation. +The property 'spring.cloud.stream.dynamicDestinations' can be used for restricting the dynamic destination names to a set known beforehand (whitelisting). +If the property is not set, any destination can be bound dynamicaly. +The BinderAwareChannelResolver can be used directly as in the following example, in which a REST controller uses a path variable to decide the target channel. +@EnableBinding +@Controller +public class SourceWithDynamicDestination { + + @Autowired + private BinderAwareChannelResolver resolver; + + @RequestMapping(path = "/{target}", method = POST, consumes = "*/*") + @ResponseStatus(HttpStatus.ACCEPTED) + public void handleRequest(@RequestBody String body, @PathVariable("target") target, + @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) { + sendMessage(body, target, contentType); + } + + private void sendMessage(String body, String target, Object contentType) { + resolver.resolveDestination(target).send(MessageBuilder.createMessage(body, + new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType)))); + } +} +After starting the application on the default port 8080, when sending the following data: +curl -H "Content-Type: application/json" -X POST -d "customer-1" http://localhost:8080/customers + +curl -H "Content-Type: application/json" -X POST -d "order-1" http://localhost:8080/orders +The destinations 'customers' and 'orders' are created in the broker (for example: exchange in case of Rabbit or topic in case of Kafka) with the names 'customers' and 'orders', and the data is published to the appropriate destinations. +The BinderAwareChannelResolver is a general purpose Spring Integration DestinationResolver and can be injected in other components. +For example, in a router using a SpEL expression based on the target field of an incoming JSON message. +@EnableBinding +@Controller +public class SourceWithDynamicDestination { + + @Autowired + private BinderAwareChannelResolver resolver; + + + @RequestMapping(path = "/", method = POST, consumes = "application/json") + @ResponseStatus(HttpStatus.ACCEPTED) + public void handleRequest(@RequestBody String body, @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) { + sendMessage(body, contentType); + } + + private void sendMessage(Object body, Object contentType) { + routerChannel().send(MessageBuilder.createMessage(body, + new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType)))); + } + + @Bean(name = "routerChannel") + public MessageChannel routerChannel() { + return new DirectChannel(); + } + + @Bean + @ServiceActivator(inputChannel = "routerChannel") + public ExpressionEvaluatingRouter router() { + ExpressionEvaluatingRouter router = + new ExpressionEvaluatingRouter(new SpelExpressionParser().parseExpression("payload.target")); + router.setDefaultOutputChannelName("default-output"); + router.setChannelResolver(resolver); + return router; + } +} +
+ + +Content Type and Transformation +To allow you to propagate information about the content type of produced messages, Spring Cloud Stream attaches, by default, a contentType header to outbound messages. +For middleware that does not directly support headers, Spring Cloud Stream provides its own mechanism of automatically wrapping outbound messages in an envelope of its own. +For middleware that does support headers, Spring Cloud Stream applications may receive messages with a given content type from non-Spring Cloud Stream applications. +Spring Cloud Stream can handle messages based on this information in two ways: + + +Through its contentType settings on inbound and outbound channels + + +Through its argument mapping performed for methods annotated with @StreamListener + + +Spring Cloud Stream allows you to declaratively configure type conversion for inputs and outputs using the spring.cloud.stream.bindings.<channelName>.content-type property of a binding. +Note that general type conversion may also be accomplished easily by using a transformer inside your application. +Currently, Spring Cloud Stream natively supports the following type conversions commonly used in streams: + + +JSON to/from POJO + + +JSON to/from org.springframework.tuple.Tuple + + +Object to/from byte[] : Either the raw bytes serialized for remote transport, bytes emitted by an application, or converted to bytes using Java serialization(requires the object to be Serializable) + + +String to/from byte[] + + +Object to plain text (invokes the object’s toString() method) + + +Where JSON represents either a byte array or String payload containing JSON. +Currently, Objects may be converted from a JSON byte array or String. +Converting to JSON always produces a String. +If no content-type property is set on an outbound channel, Spring Cloud Stream will serialize the payload using a serializer based on the Kryo serialization framework. +Deserializing messages at the destination requires the payload class to be present on the receiver’s classpath. +
+MIME types +content-type values are parsed as media types, e.g., application/json or text/plain;charset=UTF-8. +MIME types are especially useful for indicating how to convert to String or byte[] content. +Spring Cloud Stream also uses MIME type format to represent Java types, using the general type application/x-java-object with a type parameter. +For example, application/x-java-object;type=java.util.Map or application/x-java-object;type=com.bar.Foo can be set as the content-type property of an input binding. +In addition, Spring Cloud Stream provides custom MIME types, notably, application/x-spring-tuple to specify a Tuple. +
+
+MIME types and Java types +The type conversions Spring Cloud Stream provides out of the box are summarized in the following table: +'Source Payload' means the payload before conversion and 'Target Payload' means the 'payload' after conversion. +The type conversion can occur either on the 'producer' side (output) or at the 'consumer' side (input). + + + + + + + + + +Source Payload +Target Payload +content-type header (source message) +content-type header (after conversion) +Comments + + + + +POJO +JSON String +ignored +application/json + + + +Tuple +JSON String +ignored +application/json +JSON is tailored for Tuple + + +POJO +String (toString()) +ignored +text/plain, java.lang.String + + + +POJO +byte[] (java.io serialized) +ignored +application/x-java-serialized-object + + + +JSON byte[] or String +POJO +application/json (or none) +application/x-java-object + + + +byte[] or String +Serializable +application/x-java-serialized-object +application/x-java-object + + + +JSON byte[] or String +Tuple +application/json (or none) +application/x-spring-tuple + + + +byte[] +String +any +text/plain, java.lang.String +will apply any Charset specified in the content-type header + + +String +byte[] +any +application/octet-stream +will apply any Charset specified in the content-type header + + + + + +Conversion applies to payloads that require type conversion. +For example, if an application produces an XML string with outputType=application/json, the payload will not be converted from XML to JSON. +This is because the payload send to the outbound channel is already a String so no conversion will be applied at runtime. +It is also important to note that when using the default serialization mechanism, the payload class must be shared between the sending and receiving application, and compatible with the binary content. +This can create issues when application code changes independently in the two applications, as the binary format and code may become incompatible. + + +While conversion is supported for both inbound and outbound channels, it is especially recommended to be used for the conversion of outbound messages. +For the conversion of inbound messages, especially when the target is a POJO, the @StreamListener support will perform the conversion automatically. + +
+
+Customizing message conversion +Besides the conversions that it supports out of the box, Spring Cloud Stream also supports registering your own message conversion implementations. +This allows you to send and receive data in a variety of custom formats, including binary, and associate them with specific contentTypes. +Spring Cloud Stream registers all the beans of type org.springframework.messaging.converter.MessageConverter as custom message converters along with the out of the box message converters. +If your message converter needs to work with a specific content-type and target class (for both input and output), then the message converter needs to extend org.springframework.messaging.converter.AbstractMessageConverter. +For conversion when using @StreamListener, a message converter that implements org.springframework.messaging.converter.MessageConverter would suffice. +Here is an example of creating a message converter bean (with the content-type application/bar) inside a Spring Cloud Stream application: +@EnableBinding(Sink.class) +@SpringBootApplication +public static class SinkApplication { + + ... + + @Bean + public MessageConverter customMessageConverter() { + return new MyCustomMessageConverter(); + } +public class MyCustomMessageConverter extends AbstractMessageConverter { + + public MyCustomMessageConverter() { + super(new MimeType("application", "bar")); + } + + @Override + protected boolean supports(Class<?> clazz) { + return (Bar.class == clazz); + } + + @Override + protected Object convertFromInternal(Message<?> message, Class<?> targetClass, Object conversionHint) { + Object payload = message.getPayload(); + return (payload instanceof Bar ? payload : new Bar((byte[]) payload)); + } +} +Spring Cloud Stream also provides support for Avro-based converters and schema evolution. +See the specific section for details. +
+
+<literal>@StreamListener</literal> and Message Conversion +The @StreamListener annotation provides a convenient way for converting incoming messages without the need to specify the content type of an input channel. +During the dispatching process to methods annotated with @StreamListener, a conversion will be applied automatically if the argument requires it. +For example, let’s consider a message with the String content {"greeting":"Hello, world"} and a content-type header of application/json is received on the input channel. +Let us consider the following application that receives it: +public class GreetingMessage { + + String greeting; + + public String getGreeting() { + return greeting; + } + + public void setGreeting(String greeting) { + this.greeting = greeting; + } +} + +@EnableBinding(Sink.class) +@EnableAutoConfiguration +public static class GreetingSink { + + @StreamListener(Sink.INPUT) + public void receive(Greeting greeting) { + // handle Greeting + } + } +The argument of the method will be populated automatically with the POJO containing the unmarshalled form of the JSON String. +
+ + +Schema Evolution Support +Spring Cloud Stream provides support for schema evolution so that the data can be evolved over time and still work with older or newer producers and consumers and vice versa. +Most serialization models, especially the ones that aim for portability across different platforms and languages, rely on a schema that describes how the data is serialized in the binary payload. +In order to serialize the data and then to interpret it, both the sending and receiving sides must have access to a schema that describes the binary format. +In certain cases, the schema can be inferred from the payload type on serialization or from the target type on deserialization. +However, many applications benefit from having access to an explicit schema that describes the binary data format. +A schema registry lets you store schema information in a textual format (typically JSON) and makes that information accessible to various applications that need it to receive and send data in binary format. +A schema is referenceable as a tuple consisting of: + + +A subject that is the logical name of the schema + + +The schema version + + +The schema format, which describes the binary format of the data + + +This following sections goes through the details of various components involved in schema evolution process. +
+Schema Registry Client +The client-side abstraction for interacting with schema registry servers is the SchemaRegistryClient interface, which has the following structure: +public interface SchemaRegistryClient { + + SchemaRegistrationResponse register(String subject, String format, String schema); + + String fetch(SchemaReference schemaReference); + + String fetch(Integer id); + +} +Spring Cloud Stream provides out-of-the-box implementations for interacting with its own schema server and for interacting with the Confluent Schema Registry. +A client for the Spring Cloud Stream schema registry can be configured by using the @EnableSchemaRegistryClient, as follows: + @EnableBinding(Sink.class) + @SpringBootApplication + @EnableSchemaRegistryClient + public static class AvroSinkApplication { + ... + } + +The default converter is optimized to cache not only the schemas from the remote server but also the parse() and toString() methods, which are quite expensive. +Because of this, it uses a DefaultSchemaRegistryClient that does not cache responses. +If you intend to change the default behavior, you can use the client directly on your code and override it to the desired outcome. +To do so, you have to add the property spring.cloud.stream.schemaRegistryClient.cached=true to your application properties. + +
+Schema Registry Client Properties +The Schema Registry Client supports the following properties: + + +spring.cloud.stream.schemaRegistryClient.endpoint + +The location of the schema-server. +When setting this, use a full URL, including protocol (http or https) , port, and context path. + + + +Default + +http://localhost:8990/ + + + +spring.cloud.stream.schemaRegistryClient.cached + +Whether the client should cache schema server responses. +Normally set to false, as the caching happens in the message converter. +Clients using the schema registry client should set this to true. + + + +Default + +true + + + +
+
+
+Avro Schema Registry Client Message Converters +For applications that have a SchemaRegistryClient bean registered with the application context, Spring Cloud Stream auto configures an Apache Avro message converter for schema management. +This eases schema evolution, as applications that receive messages can get easy access to a writer schema that can be reconciled with their own reader schema. +For outbound messages, if the content type of the channel is set to application/*+avro, the MessageConverter is activated, as shown in the following example: +spring.cloud.stream.bindings.output.contentType=application/*+avro +During the outbound conversion, the message converter tries to infer the schema of each outbound messages (based on its type) and register it to a subject (based on the payload type) by using the SchemaRegistryClient. +If an identical schema is already found, then a reference to it is retrieved. +If not, the schema is registered, and a new version number is provided. +The message is sent with a contentType header by using the following scheme: application/[prefix].[subject].v[version]+avro, where prefix is configurable and subject is deduced from the payload type. +For example, a message of the type User might be sent as a binary payload with a content type of application/vnd.user.v2+avro, where user is the subject and 2 is the version number. +When receiving messages, the converter infers the schema reference from the header of the incoming message and tries to retrieve it. The schema is used as the writer schema in the deserialization process. +
+Avro Schema Registry Message Converter Properties +If you have enabled Avro based schema registry client by setting spring.cloud.stream.bindings.output.contentType=application/*+avro, you can customize the behavior of the registration by setting the following properties. + + +spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled + +Enable if you want the converter to use reflection to infer a Schema from a POJO. +Default: false + + + +spring.cloud.stream.schema.avro.readerSchema + +Avro compares schema versions by looking at a writer schema (origin payload) and a reader schema (your application payload). See the Avro documentation for more information. If set, this overrides any lookups at the schema server and uses the local schema as the reader schema. +Default: null + + + +spring.cloud.stream.schema.avro.schemaLocations + +Registers any .avsc files listed in this property with the Schema Server. +Default: empty + + + +spring.cloud.stream.schema.avro.prefix + +The prefix to be used on the Content-Type header. +Default: vnd + + + +
+
+
+Apache Avro Message Converters +Spring Cloud Stream provides support for schema-based message converters through its spring-cloud-stream-schema module. +Currently, the only serialization format supported out of the box for schema-based message converters is Apache Avro, with more formats to be added in future versions. +The spring-cloud-stream-schema module contains two types of message converters that can be used for Apache Avro serialization: + + +Converters that use the class information of the serialized or deserialized objects or a schema with a location known at startup. + + +Converters that use a schema registry. They locate the schemas at runtime and dynamically register new schemas as domain objects evolve. + + +
+
+Converters with Schema Support +The AvroSchemaMessageConverter supports serializing and deserializing messages either by using a predefined schema or by using the schema information available in the class (either reflectively or contained in the SpecificRecord). +If you provide a custom converter, then the default AvroSchemaMessageConverter bean is not created. The following example shows a custom converter: +To use custom converters, you can simply add it to the application context, optionally specifying one or more MimeTypes with which to associate it. +The default MimeType is application/avro. +If the target type of the conversion is a GenericRecord, a schema must be set. +The following example shows how to configure a converter in a sink application by registering the Apache Avro MessageConverter without a predefined schema. +In this example, note that the mime type value is avro/bytes, not the default application/avro. +@EnableBinding(Sink.class) +@SpringBootApplication +public static class SinkApplication { + + ... + + @Bean + public MessageConverter userMessageConverter() { + return new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes")); + } +} +Conversely, the following application registers a converter with a predefined schema (found on the classpath): +@EnableBinding(Sink.class) +@SpringBootApplication +public static class SinkApplication { + + ... + + @Bean + public MessageConverter userMessageConverter() { + AvroSchemaMessageConverter converter = new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes")); + converter.setSchemaLocation(new ClassPathResource("schemas/User.avro")); + return converter; + } +} +
+
+Schema Registry Server +Spring Cloud Stream provides a schema registry server implementation. +To use it, you can add the spring-cloud-stream-schema-server artifact to your project and use the @EnableSchemaRegistryServer annotation, which adds the schema registry server REST controller to your application. +This annotation is intended to be used with Spring Boot web applications, and the listening port of the server is controlled by the server.port property. +The spring.cloud.stream.schema.server.path property can be used to control the root path of the schema server (especially when it is embedded in other applications). +The spring.cloud.stream.schema.server.allowSchemaDeletion boolean property enables the deletion of a schema. By default, this is disabled. +The schema registry server uses a relational database to store the schemas. +By default, it uses an embedded database. +You can customize the schema storage by using the Spring Boot SQL database and JDBC configuration options. +The following example shows a Spring Boot application that enables the schema registry: +@SpringBootApplication +@EnableSchemaRegistryServer +public class SchemaRegistryServerApplication { + public static void main(String[] args) { + SpringApplication.run(SchemaRegistryServerApplication.class, args); + } +} +
+Schema Registry Server API +The Schema Registry Server API consists of the following operations: + + +POST / — see “” + + +'GET /{subject}/{format}/{version}' — see “” + + +GET /{subject}/{format} — see “” + + +GET /schemas/{id} — see “” + + +DELETE /{subject}/{format}/{version} — see “” + + +DELETE /schemas/{id} — see “” + + +DELETE /{subject} — see “” + + +
+Registering a New Schema +To register a new schema, send a POST request to the / endpoint. +The / accepts a JSON payload with the following fields: + + +subject: The schema subject + + +format: The schema format + + +definition: The schema definition + + +Its response is a schema object in JSON, with the following fields: + + +id: The schema ID + + +subject: The schema subject + + +format: The schema format + + +version: The schema version + + +definition: The schema definition + + +
+
+Retrieving an Existing Schema by Subject, Format, and Version +To retrieve an existing schema by subject, format, and version, send GET request to the /{subject}/{format}/{version} endpoint. +Its response is a schema object in JSON, with the following fields: + + +id: The schema ID + + +subject: The schema subject + + +format: The schema format + + +version: The schema version + + +definition: The schema definition + + +
+
+Retrieving an Existing Schema by Subject and Format +To retrieve an existing schema by subject and format, send a GET request to the /subject/format endpoint. +Its response is a list of schemas with each schema object in JSON, with the following fields: + + +id: The schema ID + + +subject: The schema subject + + +format: The schema format + + +version: The schema version + + +definition: The schema definition + + +
+
+Retrieving an Existing Schema by ID +To retrieve a schema by its ID, send a GET request to the /schemas/{id} endpoint. +Its response is a schema object in JSON, with the following fields: + + +id: The schema ID + + +subject: The schema subject + + +format: The schema format + + +version: The schema version + + +definition: The schema definition + + +
+
+Deleting a Schema by Subject, Format, and Version +To delete a schema identified by its subject, format, and version, send a DELETE request to the /{subject}/{format}/{version} endpoint. +
+
+Deleting a Schema by ID +To delete a schema by its ID, send a DELETE request to the /schemas/{id} endpoint. +
+
+Deleting a Schema by Subject +DELETE /{subject} +Delete existing schemas by their subject. + +This note applies to users of Spring Cloud Stream 1.1.0.RELEASE only. +Spring Cloud Stream 1.1.0.RELEASE used the table name, schema, for storing Schema objects. Schema is a keyword in a number of database implementations. +To avoid any conflicts in the future, starting with 1.1.1.RELEASE, we have opted for the name SCHEMA_REPOSITORY for the storage table. +Any Spring Cloud Stream 1.1.0.RELEASE users who upgrade should migrate their existing schemas to the new table before upgrading. + +
+
+
+Using Confluent’s Schema Registry +The default configuration creates a DefaultSchemaRegistryClient bean. +If you want to use the Confluent schema registry, you need to create a bean of type ConfluentSchemaRegistryClient, which supersedes the one configured by default by the framework. The following example shows how to create such a bean: +@Bean +public SchemaRegistryClient schemaRegistryClient(@Value("${spring.cloud.stream.schemaRegistryClient.endpoint}") String endpoint){ + ConfluentSchemaRegistryClient client = new ConfluentSchemaRegistryClient(); + client.setEndpoint(endpoint); + return client; +} + +The ConfluentSchemaRegistryClient is tested against Confluent platform version 4.0.0. + +
+
+
+Schema Registration and Resolution +To better understand how Spring Cloud Stream registers and resolves new schemas and its use of Avro schema comparison features, we provide two separate subsections: + + +“” + + +“” + + +
+Schema Registration Process (Serialization) +The first part of the registration process is extracting a schema from the payload that is being sent over a channel. +Avro types such as SpecificRecord or GenericRecord already contain a schema, which can be retrieved immediately from the instance. +In the case of POJOs, a schema is inferred if the spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled property is set to true (the default). +
+Schema Writer Resolution Process + + + + +schema resolution + +
+Ones a schema is obtained, the converter loads its metadata (version) from the remote server. +First, it queries a local cache. If no result is found, it submits the data to the server, which replies with versioning information. +The converter always caches the results to avoid the overhead of querying the Schema Server for every new message that needs to be serialized. +
+Schema Registration Process + + + + +registration + +
+With the schema version information, the converter sets the contentType header of the message to carry the version information — for example: application/vnd.user.v1+avro. +
+
+Schema Resolution Process (Deserialization) +When reading messages that contain version information (that is, a contentType header with a scheme like the one described under “”), the converter queries the Schema server to fetch the writer schema of the message. +Once it has found the correct schema of the incoming message, it retrieves the reader schema and, by using Avro’s schema resolution support, reads it into the reader definition (setting defaults and any missing properties). +
+Schema Reading Resolution Process + + + + +schema reading + +
+ +You should understand the difference between a writer schema (the application that wrote the message) and a reader schema (the receiving application). +We suggest taking a moment to read the Avro terminology and understand the process. +Spring Cloud Stream always fetches the writer schema to determine how to read a message. +If you want to get Avro’s schema evolution support working, you need to make sure that a readerSchema was properly set for your application. + +
+
+ + +Inter-Application Communication +
+Connecting Multiple Application Instances +While Spring Cloud Stream makes it easy for individual Spring Boot applications to connect to messaging systems, the typical scenario for Spring Cloud Stream is the creation of multi-application pipelines, where microservice applications send data to each other. +You can achieve this scenario by correlating the input and output destinations of adjacent applications. +Supposing that a design calls for the Time Source application to send data to the Log Sink application, you can use a common destination named ticktock for bindings within both applications. +Time Source (that has the channel name output) will set the following property: +spring.cloud.stream.bindings.output.destination=ticktock +Log Sink (that has the channel name input) will set the following property: +spring.cloud.stream.bindings.input.destination=ticktock +
+
+Instance Index and Instance Count +When scaling up Spring Cloud Stream applications, each instance can receive information about how many other instances of the same application exist and what its own instance index is. +Spring Cloud Stream does this through the spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex properties. +For example, if there are three instances of a HDFS sink application, all three instances will have spring.cloud.stream.instanceCount set to 3, and the individual applications will have spring.cloud.stream.instanceIndex set to 0, 1, and 2, respectively. +When Spring Cloud Stream applications are deployed via Spring Cloud Data Flow, these properties are configured automatically; when Spring Cloud Stream applications are launched independently, these properties must be set correctly. +By default, spring.cloud.stream.instanceCount is 1, and spring.cloud.stream.instanceIndex is 0. +In a scaled-up scenario, correct configuration of these two properties is important for addressing partitioning behavior (see below) in general, and the two properties are always required by certain binders (e.g., the Kafka binder) in order to ensure that data are split correctly across multiple consumer instances. +
+
+Partitioning +
+Configuring Output Bindings for Partitioning +An output binding is configured to send partitioned data by setting one and only one of its partitionKeyExpression or partitionKeyExtractorClass properties, as well as its partitionCount property. +For example, the following is a valid and typical configuration: +spring.cloud.stream.bindings.output.producer.partitionKeyExpression=payload.id +spring.cloud.stream.bindings.output.producer.partitionCount=5 +Based on the above example configuration, data will be sent to the target partition using the following logic. +A partition key’s value is calculated for each message sent to a partitioned output channel based on the partitionKeyExpression. +The partitionKeyExpression is a SpEL expression which is evaluated against the outbound message for extracting the partitioning key. +If a SpEL expression is not sufficient for your needs, you can instead calculate the partition key value by setting the property partitionKeyExtractorClass to a class which implements the org.springframework.cloud.stream.binder.PartitionKeyExtractorStrategy interface. +While the SpEL expression should usually suffice, more complex cases may use the custom implementation strategy. +In that case, the property 'partitionKeyExtractorClass' can be set as follows: +spring.cloud.stream.bindings.output.producer.partitionKeyExtractorClass=com.example.MyKeyExtractor +spring.cloud.stream.bindings.output.producer.partitionCount=5 +Once the message key is calculated, the partition selection process will determine the target partition as a value between 0 and partitionCount - 1. +The default calculation, applicable in most scenarios, is based on the formula key.hashCode() % partitionCount. +This can be customized on the binding, either by setting a SpEL expression to be evaluated against the 'key' (via the partitionSelectorExpression property) or by setting a org.springframework.cloud.stream.binder.PartitionSelectorStrategy implementation (via the partitionSelectorClass property). +The binding level properties for 'partitionSelectorExpression' and 'partitionSelectorClass' can be specified similar to the way 'partitionKeyExpression' and 'partitionKeyExtractorClass' properties are specified in the above examples. +Additional properties can be configured for more advanced scenarios, as described in the following section. +
+Spring-managed custom <literal>PartitionKeyExtractorClass</literal> implementations +In the example above, a custom strategy such as MyKeyExtractor is instantiated by the Spring Cloud Stream directly. +In some cases, it is necessary for such a custom strategy implementation to be created as a Spring bean, for being able to be managed by Spring, so that it can perform dependency injection, property binding, etc. +This can be done by configuring it as a @Bean in the application context and using the fully qualified class name as the bean’s name, as in the following example. +@Bean(name="com.example.MyKeyExtractor") +public MyKeyExtractor extractor() { + return new MyKeyExtractor(); +} +As a Spring bean, the custom strategy benefits from the full lifecycle of a Spring bean. +For example, if the implementation need access to the application context directly, it can make implement 'ApplicationContextAware'. +
+
+Configuring Input Bindings for Partitioning +An input binding (with the channel name input) is configured to receive partitioned data by setting its partitioned property, as well as the instanceIndex and instanceCount properties on the application itself, as in the following example: +spring.cloud.stream.bindings.input.consumer.partitioned=true +spring.cloud.stream.instanceIndex=3 +spring.cloud.stream.instanceCount=5 +The instanceCount value represents the total number of application instances between which the data need to be partitioned, and the instanceIndex must be a unique value across the multiple instances, between 0 and instanceCount - 1. +The instance index helps each application instance to identify the unique partition (or, in the case of Kafka, the partition set) from which it receives data. +It is important to set both values correctly in order to ensure that all of the data is consumed and that the application instances receive mutually exclusive datasets. +While a scenario which using multiple instances for partitioned data processing may be complex to set up in a standalone case, Spring Cloud Dataflow can simplify the process significantly by populating both the input and output values correctly as well as relying on the runtime infrastructure to provide information about the instance index and instance count. +
+
+
+ + +Testing +Spring Cloud Stream provides support for testing your microservice applications without connecting to a messaging system. +You can do that by using the TestSupportBinder provided by the spring-cloud-stream-test-support library, which can be added as a test dependency to the application: + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-test-support</artifactId> + <scope>test</scope> + </dependency> + +The TestSupportBinder uses the Spring Boot autoconfiguration mechanism to supersede the other binders found on the classpath. +Therefore, when adding a binder as a dependency, make sure that the test scope is being used. + +The TestSupportBinder allows users to interact with the bound channels and inspect what messages are sent and received by the application +For outbound message channels, the TestSupportBinder registers a single subscriber and retains the messages emitted by the application in a MessageCollector. +They can be retrieved during tests and have assertions made against them. +The user can also send messages to inbound message channels, so that the consumer application can consume the messages. +The following example shows how to test both input and output channels on a processor. +@RunWith(SpringRunner.class) +@SpringBootTest(webEnvironment= SpringBootTest.WebEnvironment.RANDOM_PORT) +public class ExampleTest { + + @Autowired + private Processor processor; + + @Autowired + private MessageCollector messageCollector; + + @Test + @SuppressWarnings("unchecked") + public void testWiring() { + Message<String> message = new GenericMessage<>("hello"); + processor.input().send(message); + Message<String> received = (Message<String>) messageCollector.forChannel(processor.output()).poll(); + assertThat(received.getPayload(), equalTo("hello world")); + } + + + @SpringBootApplication + @EnableBinding(Processor.class) + public static class MyProcessor { + + @Autowired + private Processor channels; + + @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT) + public String transform(String in) { + return in + " world"; + } + } +} +In the example above, we are creating an application that has an input and an output channel, bound through the Processor interface. +The bound interface is injected into the test so we can have access to both channels. +We are sending a message on the input channel and we are using the MessageCollector provided by Spring Cloud Stream’s test support to capture the message has been sent to the output channel as a result. +Once we have received the message, we can validate that the component functions correctly. +
+Disabling the test binder autoconfiguration +The intent behind the test binder superseding all the other binders on the classpath is to make it easy to test your applications without making changes to your production dependencies. +In some cases (e.g. integration tests) it is useful to use the actual production binders instead, and that requires disabling the test binder autoconfiguration. +In order to do so, you can exclude the org.springframework.cloud.stream.test.binder.TestSupportBinderAutoConfiguration class using one of the Spring Boot autoconfiguration exclusion mechanisms, as in the following example. + @SpringBootApplication(exclude = TestSupportBinderAutoConfiguration.class) + @EnableBinding(Processor.class) + public static class MyProcessor { + + @Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT) + public String transform(String in) { + return in + " world"; + } + } +When autoconfiguration is disabled, the test binder is available on the classpath, and its defaultCandidate property is set to false, so that it does not interfere with the regular user configuration. It can be referenced under the name test e.g.: +spring.cloud.stream.defaultBinder=test +
+ + +Health Indicator +Spring Cloud Stream provides a health indicator for binders. +It is registered under the name binders and can be enabled or disabled by setting the management.health.binders.enabled property. +By default management.health.binders.enabled is set to false. +Setting management.health.binders.enabled to true enables the health indicator, allowing you to access the /health endpoint to retrieve the binder health indicators. +Health indicators are binder-specific and certain binder implementations may not necessarily provide a health indicator. + + +Metrics Emitter +Spring Cloud Stream provides a module called spring-cloud-stream-metrics that can be used to emit any available metric from Spring Boot metrics endpoint to a named channel. +This module allow operators to collect metrics from stream applications without relying on polling their endpoints. +The module is activated when you set the destination name for metrics binding, e.g. spring.cloud.stream.bindings.applicationMetrics.destination=<DESTINATION_NAME>. +applicationMetrics can be configured in a similar fashion to any other producer binding. +The default contentType setting of applicationMetrics is application/json. +The following properties can be used for customizing the emission of metrics: + + +spring.cloud.stream.metrics.key + +The name of the metric being emitted. Should be an unique value per application. + + + +Default + +${spring.application.name:${vcap.application.name:${spring.config.name:application}}} + + + +spring.cloud.stream.metrics.prefix + +Prefix string to be prepended to the metrics key. +Default: `` + + + +spring.cloud.stream.metrics.properties + +Just like the includes option, it allows white listing application properties that will be added to the metrics payload +Default: null. + + + +A detailed overview of the metrics export process can be found in the Spring Boot reference documentation. +Spring Cloud Stream provides a metric exporter named application that can be configured via regular Spring Boot metrics configuration properties. +The exporter can be configured either by using the global Spring Boot configuration settings for exporters, or by using exporter-specific properties. +For using the global configuration settings, the properties should be prefixed by spring.metric.export (e.g. spring.metric.export.includes=integration**). +These configuration options will apply to all exporters (unless they have been configured differently). +Alternatively, if it is intended to use configuration settings that are different from the other exporters (e.g. for restricting the number of metrics published), the Spring Cloud Stream provided metrics exporter can be configured using the prefix spring.metrics.export.triggers.application (e.g. spring.metrics.export.triggers.application.includes=integration**). + +Due to Spring Boot’s relaxed binding the value of a property being included can be slightly different than the original value. +As a rule of thumb, the metric exporter will attempt to normalize all the properties in a consistent format using the dot notation (e.g. JAVA_HOME becomes java.home). +The goal of normalization is to make downstream consumers of those metrics capable of receiving property names consistently, regardless of how they are set on the monitored application (--spring.application.name or SPRING_APPLICATION_NAME would always yield spring.application.name). + +Below is a sample of the data published to the channel in JSON format by the following command: +java -jar time-source.jar \ + --spring.cloud.stream.bindings.applicationMetrics.destination=someMetrics \ + --spring.cloud.stream.metrics.properties=spring.application** \ + --spring.metrics.export.includes=integration.channel.input**,integration.channel.output** +The resulting JSON is: +{ + "name":"time-source", + "metrics":[ + { + "name":"integration.channel.output.errorRate.mean", + "value":0.0, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.errorRate.max", + "value":0.0, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.errorRate.min", + "value":0.0, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.errorRate.stdev", + "value":0.0, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.errorRate.count", + "value":0.0, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.sendCount", + "value":6.0, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.sendRate.mean", + "value":0.994885872292989, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.sendRate.max", + "value":1.006247080013156, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.sendRate.min", + "value":1.0012035220116378, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.sendRate.stdev", + "value":6.505181111084848E-4, + "timestamp":"2017-04-11T16:56:35.790Z" + }, + { + "name":"integration.channel.output.sendRate.count", + "value":6.0, + "timestamp":"2017-04-11T16:56:35.790Z" + } + ], + "createdTime":"2017-04-11T20:56:35.790Z", + "properties":{ + "spring.application.name":"time-source", + "spring.application.index":"0" + } +} + + +Samples +For Spring Cloud Stream samples, please refer to the spring-cloud-stream-samples repository on GitHub. + + +Getting Started +To get started with creating Spring Cloud Stream applications, visit the Spring Initializr and create a new Maven project named "GreetingSource". +Select Spring Boot {supported-spring-boot-version} in the dropdown. +In the Search for dependencies text box type Stream Rabbit or Stream Kafka depending on what binder you want to use. +Next, create a new class, GreetingSource, in the same package as the GreetingSourceApplication class. +Give it the following code: +import org.springframework.cloud.stream.annotation.EnableBinding; +import org.springframework.cloud.stream.messaging.Source; +import org.springframework.integration.annotation.InboundChannelAdapter; + +@EnableBinding(Source.class) +public class GreetingSource { + + @InboundChannelAdapter(Source.OUTPUT) + public String greet() { + return "hello world " + System.currentTimeMillis(); + } +} +The @EnableBinding annotation is what triggers the creation of Spring Integration infrastructure components. +Specifically, it will create a Kafka connection factory, a Kafka outbound channel adapter, and the message channel defined inside the Source interface: +public interface Source { + + String OUTPUT = "output"; + + @Output(Source.OUTPUT) + MessageChannel output(); + +} +The auto-configuration also creates a default poller, so that the greet() method will be invoked once per second. +The standard Spring Integration @InboundChannelAdapter annotation sends a message to the source’s output channel, using the return value as the payload of the message. +To test-drive this setup, run a Kafka message broker. +An easy way to do this is to use a Docker image: +# On OS X +$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=`docker-machine ip \`docker-machine active\`` --env ADVERTISED_PORT=9092 spotify/kafka + +# On Linux +$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=localhost --env ADVERTISED_PORT=9092 spotify/kafka +Build the application: +./mvnw clean package +The consumer application is coded in a similar manner. +Go back to Initializr and create another project, named LoggingSink. +Then create a new class, LoggingSink, in the same package as the class LoggingSinkApplication and with the following code: +import org.springframework.cloud.stream.annotation.EnableBinding; +import org.springframework.cloud.stream.annotation.StreamListener; +import org.springframework.cloud.stream.messaging.Sink; + +@EnableBinding(Sink.class) +public class LoggingSink { + + @StreamListener(Sink.INPUT) + public void log(String message) { + System.out.println(message); + } +} +Build the application: +./mvnw clean package +To connect the GreetingSource application to the LoggingSink application, each application must share the same destination name. +Starting up both applications as shown below, you will see the consumer application printing "hello world" and a timestamp to the console: +cd GreetingSource +java -jar target/GreetingSource-0.0.1-SNAPSHOT.jar --spring.cloud.stream.bindings.output.destination=mydest + +cd LoggingSink +java -jar target/LoggingSink-0.0.1-SNAPSHOT.jar --server.port=8090 --spring.cloud.stream.bindings.input.destination=mydest +(The different server port prevents collisions of the HTTP port used to service the Spring Boot Actuator endpoints in the two applications.) +The output of the LoggingSink application will look something like the following: +[ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8090 (http) +[ main] com.example.LoggingSinkApplication : Started LoggingSinkApplication in 6.828 seconds (JVM running for 7.371) +hello world 1458595076731 +hello world 1458595077732 +hello world 1458595078733 +hello world 1458595079734 +hello world 1458595080735 +
+Deploying Stream applications on CloudFoundry +On CloudFoundry services are usually exposed via a special environment variable called VCAP_SERVICES. +When configuring your binder connections, you can use the values from an environment variable as explained on the dataflow cloudfoundry server docs. +
+ + + +Binder Implementations + +Apache Kafka Binder + +
+Usage +For using the Apache Kafka binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates: +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-binder-kafka</artifactId> +</dependency> +Alternatively, you can also use the Spring Cloud Stream Kafka Starter. +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-stream-kafka</artifactId> +</dependency> +
+
+Apache Kafka Binder Overview +A simplified diagram of how the Apache Kafka binder operates can be seen below. +
+Kafka Binder + + + + +kafka binder + +
+The Apache Kafka Binder implementation maps each destination to an Apache Kafka topic. +The consumer group maps directly to the same Apache Kafka concept. +Partitioning also maps directly to Apache Kafka partitions as well. +
+
+Configuration Options +This section contains the configuration options used by the Apache Kafka binder. +For common configuration options and properties pertaining to binder, refer to the core documentation. +
+Kafka Binder Properties + + +spring.cloud.stream.kafka.binder.brokers + +A list of brokers to which the Kafka binder will connect. +Default: localhost. + + + +spring.cloud.stream.kafka.binder.defaultBrokerPort + + brokers allows hosts specified with or without port information (e.g., host1,host2:port2). +This sets the default port when no port is configured in the broker list. +Default: 9092. + + + +spring.cloud.stream.kafka.binder.zkNodes + +A list of ZooKeeper nodes to which the Kafka binder can connect. +Default: localhost. + + + +spring.cloud.stream.kafka.binder.defaultZkPort + + zkNodes allows hosts specified with or without port information (e.g., host1,host2:port2). +This sets the default port when no port is configured in the node list. +Default: 2181. + + + +spring.cloud.stream.kafka.binder.configuration + + Key/Value map of client properties (both producers and consumer) passed to all clients created by the binder. +Due to the fact that these properties will be used by both producers and consumers, usage should be restricted to common properties, especially security settings. +Default: Empty map. + + + +spring.cloud.stream.kafka.binder.headers + +The list of custom headers that will be transported by the binder. +Default: empty. + + + +spring.cloud.stream.kafka.binder.healthTimeout + +The time to wait to get partition information in seconds; default 60. +Health will report as down if this timer expires. +Default: 10. + + + +spring.cloud.stream.kafka.binder.offsetUpdateTimeWindow + + The frequency, in milliseconds, with which offsets are saved. +Ignored if 0. +Default: 10000. + + + +spring.cloud.stream.kafka.binder.offsetUpdateCount + + The frequency, in number of updates, which which consumed offsets are persisted. +Ignored if 0. +Mutually exclusive with offsetUpdateTimeWindow. +Default: 0. + + + +spring.cloud.stream.kafka.binder.requiredAcks + +The number of required acks on the broker. +Default: 1. + + + +spring.cloud.stream.kafka.binder.minPartitionCount + + Effective only if autoCreateTopics or autoAddPartitions is set. +The global minimum number of partitions that the binder will configure on topics on which it produces/consumes data. +It can be superseded by the partitionCount setting of the producer or by the value of instanceCount * concurrency settings of the producer (if either is larger). +Default: 1. + + + +spring.cloud.stream.kafka.binder.replicationFactor + +The replication factor of auto-created topics if autoCreateTopics is active. +Default: 1. + + + +spring.cloud.stream.kafka.binder.autoCreateTopics + + If set to true, the binder will create new topics automatically. +If set to false, the binder will rely on the topics being already configured. +In the latter case, if the topics do not exist, the binder will fail to start. +Of note, this setting is independent of the auto.topic.create.enable setting of the broker and it does not influence it: if the server is set to auto-create topics, they may be created as part of the metadata retrieval request, with default broker settings. +Default: true. + + + +spring.cloud.stream.kafka.binder.autoAddPartitions + + If set to true, the binder will create add new partitions if required. +If set to false, the binder will rely on the partition size of the topic being already configured. +If the partition count of the target topic is smaller than the expected value, the binder will fail to start. +Default: false. + + + +spring.cloud.stream.kafka.binder.socketBufferSize + +Size (in bytes) of the socket buffer to be used by the Kafka consumers. +Default: 2097152. + + + +
+
+Kafka Consumer Properties +The following properties are available for Kafka consumers only and +must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.consumer.. + + +autoRebalanceEnabled + +When true, topic partitions will be automatically rebalanced between the members of a consumer group. +When false, each consumer will be assigned a fixed set of partitions based on spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex. +This requires both spring.cloud.stream.instanceCount and spring.cloud.stream.instanceIndex properties to be set appropriately on each launched instance. +The property spring.cloud.stream.instanceCount must typically be greater than 1 in this case. +Default: true. + + + +autoCommitOffset + + Whether to autocommit offsets when a message has been processed. +If set to false, a header with the key kafka_acknowledgment of the type org.springframework.kafka.support.Acknowledgment header will be present in the inbound message. +Applications may use this header for acknowledging messages. +See the examples section for details. +When this property is set to false, Kafka binder will set the ack mode to org.springframework.kafka.listener.AbstractMessageListenerContainer.AckMode.MANUAL. +Default: true. + + + +autoCommitOnError + + Effective only if autoCommitOffset is set to true. +If set to false it suppresses auto-commits for messages that result in errors, and will commit only for successful messages, allows a stream to automatically replay from the last successfully processed message, in case of persistent failures. +If set to true, it will always auto-commit (if auto-commit is enabled). +If not set (default), it effectively has the same value as enableDlq, auto-committing erroneous messages if they are sent to a DLQ, and not committing them otherwise. +Default: not set. + + + +recoveryInterval + +The interval between connection recovery attempts, in milliseconds. +Default: 5000. + + + +startOffset + + The starting offset for new groups. +Allowed values: earliest, latest. +If the consumer group is set explicitly for the consumer 'binding' (via spring.cloud.stream.bindings.<channelName>.group), then 'startOffset' is set to earliest; otherwise it is set to latest for the anonymous consumer group. +Default: null (equivalent to earliest). + + + +enableDlq + +When set to true, it will send enable DLQ behavior for the consumer. +By default, messages that result in errors will be forwarded to a topic named error.<destination>.<group>. +The DLQ topic name can be configurable via the property dlqName. +This provides an alternative option to the more common Kafka replay scenario for the case when the number of errors is relatively small and replaying the entire original topic may be too cumbersome. +Default: false. + + + +configuration + +Map with a key/value pair containing generic Kafka consumer properties. +Default: Empty map. + + + +dlqName + +The name of the DLQ topic to receive the error messages. +Default: null (If not specified, messages that result in errors will be forwarded to a topic named error.<destination>.<group>). + + + +
+
+Kafka Producer Properties +The following properties are available for Kafka producers only and +must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.producer.. + + +bufferSize + +Upper limit, in bytes, of how much data the Kafka producer will attempt to batch before sending. +Default: 16384. + + + +sync + +Whether the producer is synchronous. +Default: false. + + + +batchTimeout + + How long the producer will wait before sending in order to allow more messages to accumulate in the same batch. +(Normally the producer does not wait at all, and simply sends all the messages that accumulated while the previous send was in progress.) A non-zero value may increase throughput at the expense of latency. +Default: 0. + + + +messageKeyExpression + + A SpEL expression evaluated against the outgoing message used to populate the key of the produced Kafka message. +For example headers.key or payload.myKey. +Default: none. + + + +configuration + +Map with a key/value pair containing generic Kafka producer properties. +Default: Empty map. + + + + +The Kafka binder will use the partitionCount setting of the producer as a hint to create a topic with the given partition count (in conjunction with the minPartitionCount, the maximum of the two being the value being used). +Exercise caution when configuring both minPartitionCount for a binder and partitionCount for an application, as the larger value will be used. +If a topic already exists with a smaller partition count and autoAddPartitions is disabled (the default), then the binder will fail to start. +If a topic already exists with a smaller partition count and autoAddPartitions is enabled, new partitions will be added. +If a topic already exists with a larger number of partitions than the maximum of (minPartitionCount and partitionCount), the existing partition count will be used. + +
+
+Usage examples +In this section, we illustrate the use of the above properties for specific scenarios. +
+Example: Setting <literal>autoCommitOffset</literal> false and relying on manual acking. +This example illustrates how one may manually acknowledge offsets in a consumer application. +This example requires that spring.cloud.stream.kafka.bindings.input.consumer.autoCommitOffset is set to false. +Use the corresponding input channel name for your example. +@SpringBootApplication +@EnableBinding(Sink.class) +public class ManuallyAcknowdledgingConsumer { + + public static void main(String[] args) { + SpringApplication.run(ManuallyAcknowdledgingConsumer.class, args); + } + + @StreamListener(Sink.INPUT) + public void process(Message<?> message) { + Acknowledgment acknowledgment = message.getHeaders().get(KafkaHeaders.ACKNOWLEDGMENT, Acknowledgment.class); + if (acknowledgment != null) { + System.out.println("Acknowledgment provided"); + acknowledgment.acknowledge(); + } + } +} +
+
+Example: security configuration +Apache Kafka 0.9 supports secure connections between client and brokers. +To take advantage of this feature, follow the guidelines in the Apache Kafka Documentation as well as the Kafka 0.9 security guidelines from the Confluent documentation. +Use the spring.cloud.stream.kafka.binder.configuration option to set security properties for all clients created by the binder. +For example, for setting security.protocol to SASL_SSL, set: +spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_SSL +All the other security properties can be set in a similar manner. +When using Kerberos, follow the instructions in the reference documentation for creating and referencing the JAAS configuration. +Spring Cloud Stream supports passing JAAS configuration information to the application using a JAAS configuration file and using Spring Boot properties. +
+Using JAAS configuration files +The JAAS, and (optionally) krb5 file locations can be set for Spring Cloud Stream applications by using system properties. +Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using a JAAS configuration file: + java -Djava.security.auth.login.config=/path.to/kafka_client_jaas.conf -jar log.jar \ + --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \ + --spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \ + --spring.cloud.stream.bindings.input.destination=stream.ticktock \ + --spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT +
+
+Using Spring Boot properties +As an alternative to having a JAAS configuration file, Spring Cloud Stream provides a mechanism for setting up the JAAS configuration for Spring Cloud Stream applications using Spring Boot properties. +The following properties can be used for configuring the login context of the Kafka client. + + +spring.cloud.stream.kafka.binder.jaas.loginModule + +The login module name. Not necessary to be set in normal cases. +Default: com.sun.security.auth.module.Krb5LoginModule. + + + +spring.cloud.stream.kafka.binder.jaas.controlFlag + +The control flag of the login module. +Default: required. + + + +spring.cloud.stream.kafka.binder.jaas.options + +Map with a key/value pair containing the login module options. +Default: Empty map. + + + +Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using Spring Boot configuration properties: + java --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \ + --spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \ + --spring.cloud.stream.bindings.input.destination=stream.ticktock \ + --spring.cloud.stream.kafka.binder.autoCreateTopics=false \ + --spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT \ + --spring.cloud.stream.kafka.binder.jaas.options.useKeyTab=true \ + --spring.cloud.stream.kafka.binder.jaas.options.storeKey=true \ + --spring.cloud.stream.kafka.binder.jaas.options.keyTab=/etc/security/keytabs/kafka_client.keytab \ + --spring.cloud.stream.kafka.binder.jaas.options.principal=kafka-client-1@EXAMPLE.COM +This represents the equivalent of the following JAAS file: +KafkaClient { + com.sun.security.auth.module.Krb5LoginModule required + useKeyTab=true + storeKey=true + keyTab="/etc/security/keytabs/kafka_client.keytab" + principal="kafka-client-1@EXAMPLE.COM"; +}; +If the topics required already exist on the broker, or will be created by an administrator, autocreation can be turned off and only client JAAS properties need to be sent. As an alternative to setting spring.cloud.stream.kafka.binder.autoCreateTopics you can simply remove the broker dependency from the application. See for details. + +Do not mix JAAS configuration files and Spring Boot properties in the same application. +If the -Djava.security.auth.login.config system property is already present, Spring Cloud Stream will ignore the Spring Boot properties. + + +Exercise caution when using the autoCreateTopics and autoAddPartitions if using Kerberos. +Usually applications may use principals that do not have administrative rights in Kafka and Zookeeper, and relying on Spring Cloud Stream to create/modify topics may fail. +In secure environments, we strongly recommend creating topics and managing ACLs administratively using Kafka tooling. + +
+
+
+Using the binder with Apache Kafka 0.10 +The default Kafka support in Spring Cloud Stream Kafka binder is for Kafka version 0.10.1.1. The binder also supports connecting to other 0.10 based versions and 0.9 clients. +In order to do this, when you create the project that contains your application, include spring-cloud-starter-stream-kafka as you normally would do for the default binder. +Then add these dependencies at the top of the <dependencies> section in the pom.xml file to override the dependencies. +Here is an example for downgrading your application to 0.10.0.1. Since it is still on the 0.10 line, the default spring-kafka and spring-integration-kafka versions can be retained. +<dependency> + <groupId>org.apache.kafka</groupId> + <artifactId>kafka_2.11</artifactId> + <version>0.10.0.1</version> + <exclusions> + <exclusion> + <groupId>org.slf4j</groupId> + <artifactId>slf4j-log4j12</artifactId> + </exclusion> + </exclusions> +</dependency> +<dependency> + <groupId>org.apache.kafka</groupId> + <artifactId>kafka-clients</artifactId> + <version>0.10.0.1</version> +</dependency> +Here is another example of using 0.9.0.1 version. +<dependency> + <groupId>org.springframework.kafka</groupId> + <artifactId>spring-kafka</artifactId> + <version>1.0.5.RELEASE</version> +</dependency> +<dependency> + <groupId>org.springframework.integration</groupId> + <artifactId>spring-integration-kafka</artifactId> + <version>2.0.1.RELEASE</version> +</dependency> +<dependency> + <groupId>org.apache.kafka</groupId> + <artifactId>kafka_2.11</artifactId> + <version>0.9.0.1</version> + <exclusions> + <exclusion> + <groupId>org.slf4j</groupId> + <artifactId>slf4j-log4j12</artifactId> + </exclusion> + </exclusions> +</dependency> +<dependency> + <groupId>org.apache.kafka</groupId> + <artifactId>kafka-clients</artifactId> + <version>0.9.0.1</version> +</dependency> + +The versions above are provided only for the sake of the example. +For best results, we recommend using the most recent 0.10-compatible versions of the projects. + +
+
+Excluding Kafka broker jar from the classpath of the binder based application +The Apache Kafka Binder uses the administrative utilities which are part of the Apache Kafka server library to create and reconfigure topics. +If the inclusion of the Apache Kafka server library and its dependencies is not necessary at runtime because the application will rely on the topics being configured administratively, the Kafka binder allows for Apache Kafka server dependency to be excluded from the application. +If you use non default versions for Kafka dependencies as advised above, all you have to do is not to include the kafka broker dependency. +If you use the default Kafka version, then ensure that you exclude the kafka broker jar from the spring-cloud-starter-stream-kafka dependency as following. +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-stream-kafka</artifactId> + <exclusions> + <exclusion> + <groupId>org.apache.kafka</groupId> + <artifactId>kafka_2.11</artifactId> + </exclusion> + </exclusions> +</dependency> +If you exclude the Apache Kafka server dependency and the topic is not present on the server, then the Apache Kafka broker will create the topic if auto topic creation is enabled on the server. +Please keep in mind that if you are relying on this, then the Kafka server will use the default number of partitions and replication factors. +On the other hand, if auto topic creation is disabled on the server, then care must be taken before running the application to create the topic with the desired number of partitions. +If you want to have full control over how partitions are allocated, then leave the default settings as they are, i.e. do not exclude the kafka broker jar and ensure that spring.cloud.stream.kafka.binder.autoCreateTopics is set to true, which is the default. +
+
+
+
+Kafka Streams Binding Capabilities of Spring Cloud Stream +Spring Cloud Stream Kafka support also includes a binder specifically designed for Kafka Streams binding. +Using this binder, applications can be written that leverage the Kafka Streams API. +For more information on Kafka Streams, see Kafka Streams API Developer Manual +Kafka Streams support in Spring Cloud Stream is based on the foundations provided by the Spring Kafka project. For details on that support, see Kafaka Streams Support in Spring Kafka. +Here are the maven coordinates for the Spring Cloud Stream KStream binder artifact. +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-binder-kstream</artifactId> +</dependency> +In addition to leveraging the Spring Cloud Stream programming model which is based on Spring Boot, one of the main other benefits that the KStream binder provides is the fact that it avoids the boilerplate configuration that one needs to write when using the Kafka Streams API directly. +High level streams DSL provided through the Kafka Streams API can be used through Spring Cloud Stream in the current support. +
+Usage example of high level streams DSL +This application will listen from a Kafka topic and write the word count for each unique word that it sees in a 5 seconds time window. +@SpringBootApplication +@EnableBinding(KStreamProcessor.class) +public class WordCountProcessorApplication { + + @StreamListener("input") + @SendTo("output") + public KStream<?, String> process(KStream<?, String> input) { + return input + .flatMapValues(value -> Arrays.asList(value.toLowerCase().split("\\W+"))) + .map((key, word) -> new KeyValue<>(word, word)) + .groupByKey(Serdes.String(), Serdes.String()) + .count(TimeWindows.of(5000), "store-name") + .toStream() + .map((w, c) -> new KeyValue<>(null, "Count for " + w.key() + ": " + c)); + } + + public static void main(String[] args) { + SpringApplication.run(WordCountProcessorApplication.class, args); + } +If you build it as Spring Boot runnable fat jar, you can run the above example in the following way: +java -jar uber.jar --spring.cloud.stream.bindings.input.destination=words --spring.cloud.stream.bindings.output.destination=counts +This means that the application will listen from the incoming Kafka topic words and write to the output topic counts. +Spring Cloud Stream will ensure that the messages from both the incoming and outgoing topics are bound as KStream objects. +As one may observe, the developer can exclusively focus on the business aspects of the code, i.e. writing the logic required in the processor rather than setting up the streams specific configuration required by the Kafka Streams infrastructure. +All those boilerplate is handled by Spring Cloud Stream behind the scenes. +
+
+Support for interactive queries +If access to the KafkaStreams is needed for interactive queries, the internal KafkaStreams instance can be accessed via KStreamBuilderFactoryBean.getKafkaStreams(). +You can autowire the KStreamBuilderFactoryBean instance provided by the KStream binder. Then you can get KafkaStreams instance from it and retrieve the underlying store, execute queries on it, etc. +
+
+Kafka Streams properties + + +configuration + +Map with a key/value pair containing properties pertaining to Kafka Streams API. +This property must be prefixed with spring.cloud.stream.kstream.binder.. +Following are some examples of using this property. + + + +spring.cloud.stream.kstream.binder.configuration.key.serde=org.apache.kafka.common.serialization.Serdes$StringSerde +spring.cloud.stream.kstream.binder.configuration.value.serde=org.apache.kafka.common.serialization.Serdes$StringSerde +spring.cloud.stream.kstream.binder.configuration.commit.interval.ms=1000 +For more information about all the properties that may go into streams configuration, see StreamsConfig JavaDocs. +There can also be binding specific properties. +For instance, you can use a different Serde for your input or output destination. +spring.cloud.stream.kstream.bindings.output.producer.keySerde=org.apache.kafka.common.serialization.Serdes$IntegerSerde +spring.cloud.stream.kstream.bindings.output.producer.valueSerde=org.apache.kafka.common.serialization.Serdes$LongSerde + + +timewindow.length + +Many streaming applications written using Kafka Streams involve windowning operations. +If you specify this property, there is a org.apache.kafka.streams.kstream.TimeWindows bean automatically provided that can be autowired in applications. +This property must be prefixed with spring.cloud.stream.kstream.. +A bean of type org.apache.kafka.streams.kstream.TimeWindows is created only if this property is provided. +Following is an example of using this property. +Values are provided in milliseconds. + + + +spring.cloud.stream.kstream.timeWindow.length=5000 + + +timewindow.advanceBy + +This property goes hand in hand with timewindow.length and has no effect on its own. +If you provide this property, the generated org.apache.kafka.streams.kstream.TimeWindows bean will automatically conatin this information. +This property must be prefixed with spring.cloud.stream.kstream.. +Following is an example of using this property. +Values are provided in milliseconds. + + + +spring.cloud.stream.kstream.timeWindow.advanceBy=1000 +
+
+
+Error Channels +Starting with version 1.3, the binder unconditionally sends exceptions to an error channel for each consumer destination, and can be configured to send async producer send failures to an error channel too. +See for more information. +The payload of the ErrorMessage for a send failure is a KafkaSendFailureException with properties: + + +failedMessage - the spring-messaging Message<?> that failed to be sent. + + +record - the raw ProducerRecord that was created from the failedMessage + + +There is no automatic handling of these exceptions (such as sending to a Dead-Letter queue); you can consume these exceptions with your own Spring Integration flow. +
+
+Kafka Metrics +Kafka binder module exposes the following metrics: +spring.cloud.stream.binder.kafka.someGroup.someTopic.lag - this metric indicates how many messages have not been yet consumed from given binder’s topic by given consumer group. +For example if the value of the metric spring.cloud.stream.binder.kafka.myGroup.myTopic.lag is 1000, then consumer group myGroup has 1000 messages to waiting to be consumed from topic myTopic. +This metric is particularly useful to provide auto-scaling feedback to PaaS platform of your choice. +
+
+Dead-Letter Topic Processing +Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them. +If the reason for the dead-lettering is transient, you may wish to route the messages back to the original topic. +However, if the problem is a permanent issue, that could cause an infinite loop. +The following spring-boot application is an example of how to route those messages back to the original topic, but moves them to a third "parking lot" topic after three attempts. +The application is simply another spring-cloud-stream application that reads from the dead-letter topic. +It terminates when no messages are received for 5 seconds. +The examples assume the original destination is so8400out and the consumer group is so8400. +There are several considerations. + + +Consider only running the rerouting when the main application is not running. +Otherwise, the retries for transient errors will be used up very quickly. + + +Alternatively, use a two-stage approach - use this application to route to a third topic, and another to route from there back to the main topic. + + +Since this technique uses a message header to keep track of retries, it won’t work with headerMode=raw. +In that case, consider adding some data to the payload (that can be ignored by the main application). + + +x-retries has to be added to the headers property spring.cloud.stream.kafka.binder.headers=x-retries on both this, and the main application so that the header is transported between the applications. + + +Since kafka is publish/subscribe, replayed messages will be sent to each consumer group, even those that successfully processed a message the first time around. + + + +application.properties + +spring.cloud.stream.bindings.input.group=so8400replay +spring.cloud.stream.bindings.input.destination=error.so8400out.so8400 + +spring.cloud.stream.bindings.output.destination=so8400out +spring.cloud.stream.bindings.output.producer.partitioned=true + +spring.cloud.stream.bindings.parkingLot.destination=so8400in.parkingLot +spring.cloud.stream.bindings.parkingLot.producer.partitioned=true + +spring.cloud.stream.kafka.binder.configuration.auto.offset.reset=earliest + +spring.cloud.stream.kafka.binder.headers=x-retries + + + +Application + +@SpringBootApplication +@EnableBinding(TwoOutputProcessor.class) +public class ReRouteDlqKApplication implements CommandLineRunner { + + private static final String X_RETRIES_HEADER = "x-retries"; + + public static void main(String[] args) { + SpringApplication.run(ReRouteDlqKApplication.class, args).close(); + } + + private final AtomicInteger processed = new AtomicInteger(); + + @Autowired + private MessageChannel parkingLot; + + @StreamListener(Processor.INPUT) + @SendTo(Processor.OUTPUT) + public Message<?> reRoute(Message<?> failed) { + processed.incrementAndGet(); + Integer retries = failed.getHeaders().get(X_RETRIES_HEADER, Integer.class); + if (retries == null) { + System.out.println("First retry for " + failed); + return MessageBuilder.fromMessage(failed) + .setHeader(X_RETRIES_HEADER, new Integer(1)) + .setHeader(BinderHeaders.PARTITION_OVERRIDE, + failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID)) + .build(); + } + else if (retries.intValue() < 3) { + System.out.println("Another retry for " + failed); + return MessageBuilder.fromMessage(failed) + .setHeader(X_RETRIES_HEADER, new Integer(retries.intValue() + 1)) + .setHeader(BinderHeaders.PARTITION_OVERRIDE, + failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID)) + .build(); + } + else { + System.out.println("Retries exhausted for " + failed); + parkingLot.send(MessageBuilder.fromMessage(failed) + .setHeader(BinderHeaders.PARTITION_OVERRIDE, + failed.getHeaders().get(KafkaHeaders.RECEIVED_PARTITION_ID)) + .build()); + } + return null; + } + + @Override + public void run(String... args) throws Exception { + while (true) { + int count = this.processed.get(); + Thread.sleep(5000); + if (count == this.processed.get()) { + System.out.println("Idle, terminating"); + return; + } + } + } + + public interface TwoOutputProcessor extends Processor { + + @Output("parkingLot") + MessageChannel parkingLot(); + + } + +} + + +
+ + +RabbitMQ Binder + +
+Usage +For using the RabbitMQ binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates: +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-binder-rabbit</artifactId> +</dependency> +Alternatively, you can also use the Spring Cloud Stream RabbitMQ Starter. +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-stream-rabbit</artifactId> +</dependency> +
+
+RabbitMQ Binder Overview +A simplified diagram of how the RabbitMQ binder operates can be seen below. +
+RabbitMQ Binder + + + + +rabbit binder + +
+The RabbitMQ Binder implementation maps each destination to a TopicExchange. +For each consumer group, a Queue will be bound to that TopicExchange. +Each consumer instance have a corresponding RabbitMQ Consumer instance for its group’s Queue. +For partitioned producers/consumers the queues are suffixed with the partition index and use the partition index as routing key. +Using the autoBindDlq option, you can optionally configure the binder to create and configure dead-letter queues (DLQs) (and a dead-letter exchange DLX). +The dead letter queue has the name of the destination, appended with .dlq. +If retry is enabled (maxAttempts > 1) failed messages will be delivered to the DLQ. +If retry is disabled (maxAttempts = 1), you should set requeueRejected to false (default) so that a failed message will be routed to the DLQ, instead of being requeued. +In addition, republishToDlq causes the binder to publish a failed message to the DLQ (instead of rejecting it); this enables additional information to be added to the message in headers, such as the stack trace in the x-exception-stacktrace header. +This option does not need retry enabled; you can republish a failed message after just one attempt. +Starting with version 1.2, you can configure the delivery mode of republished messages; see property republishDeliveryMode. + +Setting requeueRejected to true will cause the message to be requeued and redelivered continually, which is likely not what you want unless the failure issue is transient. +In general, it’s better to enable retry within the binder by setting maxAttempts to greater than one, or set republishToDlq to true. + +See for more information about these properties. +The framework does not provide any standard mechanism to consume dead-letter messages (or to re-route them back to the primary queue). +Some options are described in . + +When multiple RabbitMQ binders are used in a Spring Cloud Stream application, it is important to disable 'RabbitAutoConfiguration' to avoid the same configuration from RabbitAutoConfiguration being applied to the two binders. + +Starting with version 1.3, the RabbitMessageChannelBinder creates an internal ConnectionFactory copy for the non-transactional producers to avoid dead locks on consumers when shared, cached connections are blocked because of Memory Alarm on Broker. +
+
+Configuration Options +This section contains settings specific to the RabbitMQ Binder and bound channels. +For general binding configuration options and properties, +please refer to the Spring Cloud Stream core documentation. +
+RabbitMQ Binder Properties +By default, the RabbitMQ binder uses Spring Boot’s ConnectionFactory, and it therefore supports all Spring Boot configuration options for RabbitMQ. +(For reference, consult the Spring Boot documentation.) +RabbitMQ configuration options use the spring.rabbitmq prefix. +In addition to Spring Boot options, the RabbitMQ binder supports the following properties: + + +spring.cloud.stream.rabbit.binder.adminAddresses + + A comma-separated list of RabbitMQ management plugin URLs. +Only used when nodes contains more than one entry. +Each entry in this list must have a corresponding entry in spring.rabbitmq.addresses. +Only needed if you are using a RabbitMQ cluster and wish to consume from the node that hosts the queue. +See Queue Affinity and the LocalizedQueueConnectionFactory for more information. +Default: empty. + + + +spring.cloud.stream.rabbit.binder.nodes + + A comma-separated list of RabbitMQ node names. +When more than one entry, used to locate the server address where a queue is located. +Each entry in this list must have a corresponding entry in spring.rabbitmq.addresses. +Only needed if you are using a RabbitMQ cluster and wish to consume from the node that hosts the queue. +See Queue Affinity and the LocalizedQueueConnectionFactory for more information. +Default: empty. + + + +spring.cloud.stream.rabbit.binder.compressionLevel + + Compression level for compressed bindings. +See java.util.zip.Deflater. +Default: 1 (BEST_LEVEL). + + + +
+
+RabbitMQ Consumer Properties +The following properties are available for Rabbit consumers only and +must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.consumer.. + + +acknowledgeMode + +The acknowledge mode. +Default: AUTO. + + + +autoBindDlq + +Whether to automatically declare the DLQ and bind it to the binder DLX. +Default: false. + + + +bindingRoutingKey + +The routing key with which to bind the queue to the exchange (if bindQueue is true). +for partitioned destinations -<instanceIndex> will be appended. +Default: #. + + + +bindQueue + +Whether to bind the queue to the destination exchange; set to false if you have set up your own infrastructure and have previously created/bound the queue. +Default: true. + + + +deadLetterQueueName + +name of the DLQ +Default: prefix+destination.dlq + + + +deadLetterExchange + +a DLX to assign to the queue; if autoBindDlq is true +Default: 'prefix+DLX' + + + +deadLetterRoutingKey + +a dead letter routing key to assign to the queue; if autoBindDlq is true +Default: destination + + + +declareExchange + +Whether to declare the exchange for the destination. +Default: true. + + + +delayedExchange + +Whether to declare the exchange as a Delayed Message Exchange - requires the delayed message exchange plugin on the broker. +The x-delayed-type argument is set to the exchangeType. +Default: false. + + + +dlqDeadLetterExchange + +if a DLQ is declared, a DLX to assign to that queue +Default: none + + + +dlqDeadLetterRoutingKey + +if a DLQ is declared, a dead letter routing key to assign to that queue; default none +Default: none + + + +dlqExpires + +how long before an unused dead letter queue is deleted (ms) +Default: no expiration + + + +dlqLazy + +Declare the dead letter queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Default: false. + + + +dlqMaxLength + +maximum number of messages in the dead letter queue +Default: no limit + + + +dlqMaxLengthBytes + +maximum number of total bytes in the dead letter queue from all messages +Default: no limit + + + +dlqMaxPriority + +maximum priority of messages in the dead letter queue (0-255) +Default: none + + + +dlqTtl + +default time to live to apply to the dead letter queue when declared (ms) +Default: no limit + + + +durableSubscription + + Whether subscription should be durable. +Only effective if group is also set. +Default: true. + + + +exchangeAutoDelete + +If declareExchange is true, whether the exchange should be auto-delete (removed after the last queue is removed). +Default: true. + + + +exchangeDurable + +If declareExchange is true, whether the exchange should be durable (survives broker restart). +Default: true. + + + +exchangeType + +The exchange type; direct, fanout or topic for non-partitioned destinations; direct or topic for partitioned destinations. +Default: topic. + + + +exclusive + +Create an exclusive consumer; concurrency should be 1 when this is true; often used when strict ordering is required but enabling a hot standby instance to take over after a failure. +See recoveryInterval, which controls how often a standby instance will attempt to consume. +Default: false. + + + +expires + +how long before an unused queue is deleted (ms) +Default: no expiration + + + +failedDeclarationRetryInterval + +The interval (ms) between attempts to consume from a queue if it is missing. +Default: 5000 + + + +headerPatterns + +Patterns for headers to be mapped from inbound messages. +Default: ['*'] (all headers). + + + +lazy + +Declare the queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Default: false. + + + +maxConcurrency + +the maximum number of consumers +Default: 1. + + + +maxLength + +maximum number of messages in the queue +Default: no limit + + + +maxLengthBytes + +maximum number of total bytes in the queue from all messages +Default: no limit + + + +maxPriority + +maximum priority of messages in the queue (0-255) + + + +Default + +none + + + +missingQueuesFatal + +If the queue cannot be found, treat the condition as fatal and stop the listener container. +Defaults to false so that the container keeps trying to consume from the queue, for example when using a cluster and the node hosting a non HA queue is down. + + + +Default + +false + + + +prefetch + +Prefetch count. +Default: 1. + + + +prefix + +A prefix to be added to the name of the destination and queues. +Default: "". + + + +queueDeclarationRetries + +The number of times to retry consuming from a queue if it is missing. +Only relevant if missingQueuesFatal is true; otherwise the container keeps retrying indefinitely. + + + +Default + +3 + + + +queueNameGroupOnly + +When true, consume from a queue with a name equal to the group; otherwise the queue name is destination.group. +This is useful, for example, when using Spring Cloud Stream to consume from an existing RabbitMQ queue. +Default: false. + + + +recoveryInterval + +The interval between connection recovery attempts, in milliseconds. +Default: 5000. + + + +requeueRejected + +Whether delivery failures should be requeued when retry is disabled or republishToDlq is false. +Default: false. + + + +republishDeliveryMode + +When republishToDlq is true, specify the delivery mode of the republished message. +Default: DeliveryMode.PERSISTENT + + + +republishToDlq + + By default, messages which fail after retries are exhausted are rejected. +If a dead-letter queue (DLQ) is configured, RabbitMQ will route the failed message (unchanged) to the DLQ. +If set to true, the binder will republish failed messages to the DLQ with additional headers, including the exception message and stack trace from the cause of the final failure. +Default: false + + + +transacted + +Whether to use transacted channels. +Default: false. + + + +ttl + +default time to live to apply to the queue when declared (ms) +Default: no limit + + + +txSize + +The number of deliveries between acks. +Default: 1. + + + +
+
+Rabbit Producer Properties +The following properties are available for Rabbit producers only and +must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.producer.. + + +autoBindDlq + +Whether to automatically declare the DLQ and bind it to the binder DLX. +Default: false. + + + +batchingEnabled + +Whether to enable message batching by producers. +Default: false. + + + +batchSize + +The number of messages to buffer when batching is enabled. +Default: 100. + + + +batchBufferLimit + +Default: 10000. + + + +batchTimeout + +Default: 5000. + + + +bindingRoutingKey + +The routing key with which to bind the queue to the exchange (if bindQueue is true). +Only applies to non-partitioned destinations. +Only applies if requiredGroups are provided and then only to those groups. +Default: #. + + + +bindQueue + +Whether to bind the queue to the destination exchange; set to false if you have set up your own infrastructure and have previously created/bound the queue. +Only applies if requiredGroups are provided and then only to those groups. +Default: true. + + + +compress + +Whether data should be compressed when sent. +Default: false. + + + +deadLetterQueueName + +name of the DLQ +Only applies if requiredGroups are provided and then only to those groups. +Default: prefix+destination.dlq + + + +deadLetterExchange + +a DLX to assign to the queue; if autoBindDlq is true +Only applies if requiredGroups are provided and then only to those groups. +Default: 'prefix+DLX' + + + +deadLetterRoutingKey + +a dead letter routing key to assign to the queue; if autoBindDlq is true +Only applies if requiredGroups are provided and then only to those groups. +Default: destination + + + +declareExchange + +Whether to declare the exchange for the destination. +Default: true. + + + +delay + +A SpEL expression to evaluate the delay to apply to the message (x-delay header) - has no effect if the exchange is not a delayed message exchange. +Default: No x-delay header is set. + + + +delayedExchange + +Whether to declare the exchange as a Delayed Message Exchange - requires the delayed message exchange plugin on the broker. +The x-delayed-type argument is set to the exchangeType. +Default: false. + + + +deliveryMode + +Delivery mode. +Default: PERSISTENT. + + + +dlqDeadLetterExchange + +if a DLQ is declared, a DLX to assign to that queue +Only applies if requiredGroups are provided and then only to those groups. +Default: none + + + +dlqDeadLetterRoutingKey + +if a DLQ is declared, a dead letter routing key to assign to that queue; default none +Only applies if requiredGroups are provided and then only to those groups. +Default: none + + + +dlqExpires + +how long before an unused dead letter queue is deleted (ms) +Only applies if requiredGroups are provided and then only to those groups. +Default: no expiration + + + +dlqLazy + +Declare the dead letter queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Only applies if requiredGroups are provided and then only to those groups. + + + +dlqMaxLength + +maximum number of messages in the dead letter queue +Only applies if requiredGroups are provided and then only to those groups. +Default: no limit + + + +dlqMaxLengthBytes + +maximum number of total bytes in the dead letter queue from all messages +Only applies if requiredGroups are provided and then only to those groups. +Default: no limit + + + +dlqMaxPriority + +maximum priority of messages in the dead letter queue (0-255) +Only applies if requiredGroups are provided and then only to those groups. +Default: none + + + +dlqTtl + +default time to live to apply to the dead letter queue when declared (ms) +Only applies if requiredGroups are provided and then only to those groups. +Default: no limit + + + +exchangeAutoDelete + +If declareExchange is true, whether the exchange should be auto-delete (removed after the last queue is removed). +Default: true. + + + +exchangeDurable + +If declareExchange is true, whether the exchange should be durable (survives broker restart). +Default: true. + + + +exchangeType + +The exchange type; direct, fanout or topic for non-partitioned destinations; direct or topic for partitioned destinations. +Default: topic. + + + +expires + +how long before an unused queue is deleted (ms) +Only applies if requiredGroups are provided and then only to those groups. +Default: no expiration + + + +headerPatterns + +Patterns for headers to be mapped to outbound messages. +Default: ['*'] (all headers). + + + +lazy + +Declare the queue with the x-queue-mode=lazy argument. +See Lazy Queues. +Consider using a policy instead of this setting because using a policy allows changing the setting without deleting the queue. +Only applies if requiredGroups are provided and then only to those groups. +Default: false. + + + +maxLength + +maximum number of messages in the queue +Only applies if requiredGroups are provided and then only to those groups. +Default: no limit + + + +maxLengthBytes + +maximum number of total bytes in the queue from all messages +Only applies if requiredGroups are provided and then only to those groups. +Default: no limit + + + +maxPriority + +maximum priority of messages in the queue (0-255) +Only applies if requiredGroups are provided and then only to those groups. + + + +Default + +none + + + +prefix + +A prefix to be added to the name of the destination exchange. +Default: "". + + + +queueNameGroupOnly + +When true, consume from a queue with a name equal to the group; otherwise the queue name is destination.group. +This is useful, for example, when using Spring Cloud Stream to consume from an existing RabbitMQ queue. +Only applies if requiredGroups are provided and then only to those groups. +Default: false. + + + +routingKeyExpression + +A SpEL expression to determine the routing key to use when publishing messages. +For a fixed routing key, use a literal expression, e.g. routingKeyExpression='my.routingKey' in a properties file, or routingKeyExpression: '''my.routingKey''' in a YAML file. +Default: destination or destination-<partition> for partitioned destinations. + + + +transacted + +Whether to use transacted channels. +Default: false. + + + +ttl + +default time to live to apply to the queue when declared (ms) +Only applies if requiredGroups are provided and then only to those groups. +Default: no limit + + + + +In the case of RabbitMQ, content type headers can be set by external applications. +Spring Cloud Stream supports them as part of an extended internal protocol used for any type of transport (including transports, such as Kafka, that do not normally support headers). + +
+
+
+Retry With the RabbitMQ Binder +
+Overview +When retry is enabled within the binder, the listener container thread is suspended for any back off periods that are configured. +This might be important when strict ordering is required with a single consumer but for other use cases it prevents other messages from being processed on that thread. +An alternative to using binder retry is to set up dead lettering with time to live on the dead-letter queue (DLQ), as well as dead-letter configuration on the DLQ itself. +See for more information about the properties discussed here. +Example configuration to enable this feature: + + +Set autoBindDlq to true - the binder will create a DLQ; you can optionally specify a name in deadLetterQueueName + + +Set dlqTtl to the back off time you want to wait between redeliveries + + +Set the dlqDeadLetterExchange to the default exchange - expired messages from the DLQ will be routed to the original queue since the default deadLetterRoutingKey is the queue name (destination.group) + + +To force a message to be dead-lettered, either throw an AmqpRejectAndDontRequeueException, or set requeueRejected to true and throw any exception. +The loop will continue without end, which is fine for transient problems but you may want to give up after some number of attempts. +Fortunately, RabbitMQ provides the x-death header which allows you to determine how many cycles have occurred. +To acknowledge a message after giving up, throw an ImmediateAcknowledgeAmqpException. +
+
+Putting it All Together +--- +spring.cloud.stream.bindings.input.destination=myDestination +spring.cloud.stream.bindings.input.group=consumerGroup +#disable binder retries +spring.cloud.stream.bindings.input.consumer.max-attempts=1 +#dlx/dlq setup +spring.cloud.stream.rabbit.bindings.input.consumer.auto-bind-dlq=true +spring.cloud.stream.rabbit.bindings.input.consumer.dlq-ttl=5000 +spring.cloud.stream.rabbit.bindings.input.consumer.dlq-dead-letter-exchange= +--- +This configuration creates an exchange myDestination with queue myDestination.consumerGroup bound to a topic exchange with a wildcard routing key #. +It creates a DLQ bound to a direct exchange DLX with routing key myDestination.consumerGroup. +When messages are rejected, they are routed to the DLQ. +After 5 seconds, the message expires and is routed to the original queue using the queue name as the routing key. + +Spring Boot application + +@SpringBootApplication +@EnableBinding(Sink.class) +public class XDeathApplication { + + public static void main(String[] args) { + SpringApplication.run(XDeathApplication.class, args); + } + + @StreamListener(Sink.INPUT) + public void listen(String in, @Header(name = "x-death", required = false) Map<?,?> death) { + if (death != null && death.get("count").equals(3L)) { + // giving up - don't send to DLX + throw new ImmediateAcknowledgeAmqpException("Failed after 4 attempts"); + } + throw new AmqpRejectAndDontRequeueException("failed"); + } + +} + + +Notice that the count property in the x-death header is a Long. +
+
+
+Error Channels +Starting with version 1.3, the binder unconditionally sends exceptions to an error channel for each consumer destination, and can be configured to send async producer send failures to an error channel too. +See for more information. +With rabbitmq, there are two types of send failures: + + +returned messages + + +negatively acknowledged Publisher Confirms + + +The latter is rare; quoting the RabbitMQ documentation "[A nack] will only be delivered if an internal error occurs in the Erlang process responsible for a queue.". +As well as enabling producer error channels as described in , the RabbitMQ binder will only send messages to the channels if the connection factory is appropriately configured: + + +ccf.setPublisherConfirms(true); + + +ccf.setPublisherReturns(true); + + +When using spring boot configuration for the connection factory, set properties: + + +spring.rabbitmq.publisher-confirms + + +spring.rabbitmq.publisher-returns + + +The payload of the ErrorMessage for a returned message is a ReturnedAmqpMessageException with properties: + + +failedMessage - the spring-messaging Message<?> that failed to be sent. + + +amqpMessage - the raw spring-amqp Message + + +replyCode - an integer value indicating the reason for the failure (e.g. 312 - No route) + + +replyText - a text value indicating the reason for the failure e.g. NO_ROUTE. + + +exchange - the exchange to which the message was published. + + +routingKey - the routing key used when the message was published. + + +For negatively acknowledged confirms, the payload is a NackedAmqpMessageException with properties: + + +failedMessage - the spring-messaging Message<?> that failed to be sent. + + +nackReason - a reason (if available; you may need to examine the broker logs for more information). + + +There is no automatic handling of these exceptions (such as sending to a Dead-Letter queue); you can consume these exceptions with your own Spring Integration flow. +
+
+Dead-Letter Queue Processing +Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them. +If the reason for the dead-lettering is transient, you may wish to route the messages back to the original queue. +However, if the problem is a permanent issue, that could cause an infinite loop. +The following spring-boot application is an example of how to route those messages back to the original queue, but moves them to a third "parking lot" queue after three attempts. +The second example utilizes the RabbitMQ Delayed Message Exchange to introduce a delay to the requeued message. +In this example, the delay increases for each attempt. +These examples use a @RabbitListener to receive messages from the DLQ, you could also use RabbitTemplate.receive() in a batch process. +The examples assume the original destination is so8400in and the consumer group is so8400. +
+Non-Partitioned Destinations +The first two examples are when the destination is not partitioned. +@SpringBootApplication +public class ReRouteDlqApplication { + + private static final String ORIGINAL_QUEUE = "so8400in.so8400"; + + private static final String DLQ = ORIGINAL_QUEUE + ".dlq"; + + private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot"; + + private static final String X_RETRIES_HEADER = "x-retries"; + + public static void main(String[] args) throws Exception { + ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args); + System.out.println("Hit enter to terminate"); + System.in.read(); + context.close(); + } + + @Autowired + private RabbitTemplate rabbitTemplate; + + @RabbitListener(queues = DLQ) + public void rePublish(Message failedMessage) { + Integer retriesHeader = (Integer) failedMessage.getMessageProperties().getHeaders().get(X_RETRIES_HEADER); + if (retriesHeader == null) { + retriesHeader = Integer.valueOf(0); + } + if (retriesHeader < 3) { + failedMessage.getMessageProperties().getHeaders().put(X_RETRIES_HEADER, retriesHeader + 1); + this.rabbitTemplate.send(ORIGINAL_QUEUE, failedMessage); + } + else { + this.rabbitTemplate.send(PARKING_LOT, failedMessage); + } + } + + @Bean + public Queue parkingLot() { + return new Queue(PARKING_LOT); + } + +} +@SpringBootApplication +public class ReRouteDlqApplication { + + private static final String ORIGINAL_QUEUE = "so8400in.so8400"; + + private static final String DLQ = ORIGINAL_QUEUE + ".dlq"; + + private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot"; + + private static final String X_RETRIES_HEADER = "x-retries"; + + private static final String DELAY_EXCHANGE = "dlqReRouter"; + + public static void main(String[] args) throws Exception { + ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args); + System.out.println("Hit enter to terminate"); + System.in.read(); + context.close(); + } + + @Autowired + private RabbitTemplate rabbitTemplate; + + @RabbitListener(queues = DLQ) + public void rePublish(Message failedMessage) { + Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders(); + Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER); + if (retriesHeader == null) { + retriesHeader = Integer.valueOf(0); + } + if (retriesHeader < 3) { + headers.put(X_RETRIES_HEADER, retriesHeader + 1); + headers.put("x-delay", 5000 * retriesHeader); + this.rabbitTemplate.send(DELAY_EXCHANGE, ORIGINAL_QUEUE, failedMessage); + } + else { + this.rabbitTemplate.send(PARKING_LOT, failedMessage); + } + } + + @Bean + public DirectExchange delayExchange() { + DirectExchange exchange = new DirectExchange(DELAY_EXCHANGE); + exchange.setDelayed(true); + return exchange; + } + + @Bean + public Binding bindOriginalToDelay() { + return BindingBuilder.bind(new Queue(ORIGINAL_QUEUE)).to(delayExchange()).with(ORIGINAL_QUEUE); + } + + @Bean + public Queue parkingLot() { + return new Queue(PARKING_LOT); + } + +} +
+
+Partitioned Destinations +With partitioned destinations, there is one DLQ for all partitions and we determine the original queue from the headers. +
+republishToDlq=false +When republishToDlq is false, RabbitMQ publishes the message to the DLX/DLQ with an x-death header containing information about the original destination. +@SpringBootApplication +public class ReRouteDlqApplication { + + private static final String ORIGINAL_QUEUE = "so8400in.so8400"; + + private static final String DLQ = ORIGINAL_QUEUE + ".dlq"; + + private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot"; + + private static final String X_DEATH_HEADER = "x-death"; + + private static final String X_RETRIES_HEADER = "x-retries"; + + public static void main(String[] args) throws Exception { + ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args); + System.out.println("Hit enter to terminate"); + System.in.read(); + context.close(); + } + + @Autowired + private RabbitTemplate rabbitTemplate; + + @SuppressWarnings("unchecked") + @RabbitListener(queues = DLQ) + public void rePublish(Message failedMessage) { + Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders(); + Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER); + if (retriesHeader == null) { + retriesHeader = Integer.valueOf(0); + } + if (retriesHeader < 3) { + headers.put(X_RETRIES_HEADER, retriesHeader + 1); + List<Map<String, ?>> xDeath = (List<Map<String, ?>>) headers.get(X_DEATH_HEADER); + String exchange = (String) xDeath.get(0).get("exchange"); + List<String> routingKeys = (List<String>) xDeath.get(0).get("routing-keys"); + this.rabbitTemplate.send(exchange, routingKeys.get(0), failedMessage); + } + else { + this.rabbitTemplate.send(PARKING_LOT, failedMessage); + } + } + + @Bean + public Queue parkingLot() { + return new Queue(PARKING_LOT); + } + +} +
+
+republishToDlq=true +When republishToDlq is true, the republishing recoverer adds the original exchange and routing key to headers. +@SpringBootApplication +public class ReRouteDlqApplication { + + private static final String ORIGINAL_QUEUE = "so8400in.so8400"; + + private static final String DLQ = ORIGINAL_QUEUE + ".dlq"; + + private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot"; + + private static final String X_RETRIES_HEADER = "x-retries"; + + private static final String X_ORIGINAL_EXCHANGE_HEADER = RepublishMessageRecoverer.X_ORIGINAL_EXCHANGE; + + private static final String X_ORIGINAL_ROUTING_KEY_HEADER = RepublishMessageRecoverer.X_ORIGINAL_ROUTING_KEY; + + public static void main(String[] args) throws Exception { + ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args); + System.out.println("Hit enter to terminate"); + System.in.read(); + context.close(); + } + + @Autowired + private RabbitTemplate rabbitTemplate; + + @RabbitListener(queues = DLQ) + public void rePublish(Message failedMessage) { + Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders(); + Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER); + if (retriesHeader == null) { + retriesHeader = Integer.valueOf(0); + } + if (retriesHeader < 3) { + headers.put(X_RETRIES_HEADER, retriesHeader + 1); + String exchange = (String) headers.get(X_ORIGINAL_EXCHANGE_HEADER); + String originalRoutingKey = (String) headers.get(X_ORIGINAL_ROUTING_KEY_HEADER); + this.rabbitTemplate.send(exchange, originalRoutingKey, failedMessage); + } + else { + this.rabbitTemplate.send(PARKING_LOT, failedMessage); + } + } + + @Bean + public Queue parkingLot() { + return new Queue(PARKING_LOT); + } + +} +
+
+
+ + + +Spring Cloud Bus + +Spring Cloud Bus links nodes of a distributed system with a lightweight message broker. This can then be used to broadcast state changes (e.g. configuration changes) or other management instructions. A key idea is that the Bus is like a distributed Actuator for a Spring Boot application that is scaled out, but it can also be used as a communication channel between apps. Starters are provided for an AMQP broker as the transport or for Kafka, but the same basic feature set (and some more depending on the transport) is on the roadmap for other transports. + +Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. + + + +Quick Start +Spring Cloud Bus works by adding Spring Boot autconfiguration if it detects itself on the classpath. All you need to do to enable the bus is to add spring-cloud-starter-bus-amqp or spring-cloud-starter-bus-kafka to your dependency management and Spring Cloud takes care of the rest. Make sure the broker (RabbitMQ or Kafka) is available and configured: running on localhost you shouldn’t have to do anything, but if you are running remotely use Spring Cloud Connectors, or Spring Boot conventions to define the broker credentials, e.g. for Rabbit + +application.yml + +spring: + rabbitmq: + host: mybroker.com + port: 5672 + username: user + password: secret + + +The bus currently supports sending messages to all nodes listening or all nodes for a particular service (as defined by Eureka). More selector criteria may be added in the future (ie. only service X nodes in data center Y, etc…​). There are also some http endpoints under the /bus/* actuator namespace. There are currently two implemented. The first, /bus/env, sends key/value pairs to update each node’s Spring Environment. The second, /bus/refresh, will reload each application’s configuration, just as if they had all been pinged on their /refresh endpoint. + +The Bus starters cover Rabbit and Kafka, because those are the two most common implementations, but Spring Cloud Stream is quite flexible and binder will work combined with spring-cloud-bus. + + + +Addressing an Instance +The HTTP endpoints accept a "destination" parameter, e.g. "/bus/refresh?destination=customers:9000", where the destination is an ApplicationContext ID. If the ID is owned by an instance on the Bus then it will process the message and all other instances will ignore it. Spring Boot sets the ID for you in the ContextIdApplicationContextInitializer to a combination of the spring.application.name, active profiles and server.port by default. + + +Addressing all instances of a service +The "destination" parameter is used in a Spring PathMatcher (with the path separator as a colon :) to determine if an instance will process the message. Using the example from above, "/bus/refresh?destination=customers:**" will target all instances of the "customers" service regardless of the profiles and ports set as the ApplicationContext ID. + + +Application Context ID must be unique +The bus tries to eliminate processing an event twice, once from the original ApplicationEvent and once from the queue. To do this, it checks the sending application context id againts the current application context id. If multiple instances of a service have the same application context id, events will not be processed. Running on a local machine, each service will be on a different port and that will be part of the application context id. Cloud Foundry supplies an index to differentiate. To ensure that the application context id is the unique, set spring.application.index to something unique for each instance of a service. For example, in lattice, set spring.application.index=${INSTANCE_INDEX} in application.properties (or bootstrap.properties if using configserver). + + +Customizing the Message Broker +Spring Cloud Bus uses +Spring Cloud Stream to +broadcast the messages so to get messages to flow you only need to +include the binder implementation of your choice in the +classpath. There are convenient starters specifically for the bus with +AMQP (RabbitMQ) and Kafka +(spring-cloud-starter-bus-[amqp,kafka]). Generally speaking +Spring Cloud Stream relies on Spring Boot autoconfiguration +conventions for configuring middleware, so for instance the AMQP +broker address can be changed with spring.rabbitmq.* +configuration properties. Spring Cloud Bus has a handful of native +configuration properties in spring.cloud.bus.* +(e.g. spring.cloud.bus.destination is the name of the topic to use +the the externall middleware). Normally the defaults will suffice. +To lean more about how to customize the message broker settings +consult the Spring Cloud Stream documentation. + + +Tracing Bus Events +Bus events (subclasses of RemoteApplicationEvent) can be traced by +setting spring.cloud.bus.trace.enabled=true. If you do this then the +Spring Boot TraceRepository (if it is present) will show each event +sent and all the acks from each service instance. Example (from the +/trace endpoint): +{ + "timestamp": "2015-11-26T10:24:44.411+0000", + "info": { + "signal": "spring.cloud.bus.ack", + "type": "RefreshRemoteApplicationEvent", + "id": "c4d374b7-58ea-4928-a312-31984def293b", + "origin": "stores:8081", + "destination": "*:**" + } + }, + { + "timestamp": "2015-11-26T10:24:41.864+0000", + "info": { + "signal": "spring.cloud.bus.sent", + "type": "RefreshRemoteApplicationEvent", + "id": "c4d374b7-58ea-4928-a312-31984def293b", + "origin": "customers:9000", + "destination": "*:**" + } + }, + { + "timestamp": "2015-11-26T10:24:41.862+0000", + "info": { + "signal": "spring.cloud.bus.ack", + "type": "RefreshRemoteApplicationEvent", + "id": "c4d374b7-58ea-4928-a312-31984def293b", + "origin": "customers:9000", + "destination": "*:**" + } +} +This trace shows that a RefreshRemoteApplicationEvent was sent from +customers:9000, broadcast to all services, and it was received +(acked) by customers:9000 and stores:8081. +To handle the ack signals yourself you could add an @EventListener +for the AckRemoteApplicationEvent and SentApplicationEvent types +to your app (and enable tracing). Or you could tap into the +TraceRepository and mine the data from there. + +Any Bus application can trace acks, but sometimes it will be +useful to do this in a central service that can do more complex +queries on the data. Or forward it to a specialized tracing service. + + + +Broadcasting Your Own Events +The Bus can carry any event of type RemoteApplicationEvent, but the +default transport is JSON and the deserializer needs to know which +types are going to be used ahead of time. To register a new type it +needs to be in a subpackage of org.springframework.cloud.bus.event. +To customise the event name you can use @JsonTypeName on your custom class +or rely on the default strategy which is to use the simple name of the class. +Note that both the producer and the consumer will need access to the class +definition. +
+Registering events in custom packages +If you cannot or don’t want to use a subpackage of org.springframework.cloud.bus.event +for your custom events, you must specify which packages to scan for events of +type RemoteApplicationEvent using @RemoteApplicationEventScan. Packages +specified with @RemoteApplicationEventScan include subpackages. +For example, if you have a custom event called FooEvent: +package com.acme; + +public class FooEvent extends RemoteApplicationEvent { + ... +} +you can register this event with the deserializer in the following way: +package com.acme; + +@Configuration +@RemoteApplicationEventScan +public class BusConfiguration { + ... +} +Without specifying a value, the package of the class where @RemoteApplicationEventScan +is used will be registered. In this example com.acme will be registered using the +package of BusConfiguration. +You can also explicitly specify the packages to scan using the value, basePackages or +basePackageClasses properties on @RemoteApplicationEventScan. For example: +package com.acme; + +@Configuration +//@RemoteApplicationEventScan({"com.acme", "foo.bar"}) +//@RemoteApplicationEventScan(basePackages = {"com.acme", "foo.bar", "fizz.buzz"}) +@RemoteApplicationEventScan(basePackageClasses = BusConfiguration.class) +public class BusConfiguration { + ... +} +All examples of @RemoteApplicationEventScan above are equivalent, +in that the com.acme package will be registered by explicitly specifying the +packages on @RemoteApplicationEventScan. Note, you can specify multiple base +packages to scan. +
+ + + +Spring Cloud Sleuth + +Adrian Cole, Spencer Gibb, Marcin Grzejszczak, Dave Syer +1.3.8.RELEASE + + +Introduction +Spring Cloud Sleuth implements a distributed tracing solution for Spring Cloud. +
+Terminology +Spring Cloud Sleuth borrows Dapper’s terminology. +Span: The basic unit of work. For example, sending an RPC is a new span, as is sending a response to an +RPC. Span’s are identified by a unique 64-bit ID for the span and another 64-bit ID for the trace the span +is a part of. Spans also have other data, such as descriptions, timestamped events, key-value +annotations (tags), the ID of the span that caused them, and process ID’s (normally IP address). +Spans are started and stopped, and they keep track of their timing information. Once you create a +span, you must stop it at some point in the future. + +The initial span that starts a trace is called a root span. The value of span id +of that span is equal to trace id. + +Trace: A set of spans forming a tree-like structure. For example, if you are running a distributed +big-data store, a trace might be formed by a put request. +Annotation: is used to record existence of an event in time. Some of the core annotations used to define +the start and stop of a request are: + + +cs - Client Sent - The client has made a request. This annotation depicts the start of the span. + + +sr - Server Received - The server side got the request and will start processing it. +If one subtracts the cs timestamp from this timestamp one will receive the network latency. + + +ss - Server Sent - Annotated upon completion of request processing (when the response +got sent back to the client). If one subtracts the sr timestamp from this timestamp one +will receive the time needed by the server side to process the request. + + +cr - Client Received - Signifies the end of the span. The client has successfully received the +response from the server side. If one subtracts the cs timestamp from this timestamp one +will receive the whole time needed by the client to receive the response from the server. + + +Visualization of what Span and Trace will look in a system together with the Zipkin annotations: + + + + + +Trace Info propagation + + +Each color of a note signifies a span (7 spans - from A to G). If you have such information in the note: +Trace Id = X +Span Id = D +Client Sent +That means that the current span has Trace-Id set to X, Span-Id set to D. It also has emitted + Client Sent event. +This is how the visualization of the parent / child relationship of spans would look like: + + + + + +Parent child relationship + + +
+
+Purpose +In the following sections the example from the image above will be taken into consideration. +
+Distributed tracing with Zipkin +Altogether there are 7 spans . If you go to traces in Zipkin you will see this number in the second trace: + + + + + +Traces + + +However if you pick a particular trace then you will see 4 spans: + + + + + +Traces Info propagation + + + +When picking a particular trace you will see merged spans. That means that if there were 2 spans sent to +Zipkin with Server Received and Server Sent / Client Received and Client Sent +annotations then they will presented as a single span. + +Why is there a difference between the 7 and 4 spans in this case? + + +2 spans come from http:/start span. It has the Server Received (SR) and Server Sent (SS) annotations. + + +2 spans come from the RPC call from service1 to service2 to the http:/foo endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service1 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service2 side. Physically there are 2 spans but they form 1 logical span related to an RPC call. + + +2 spans come from the RPC call from service2 to service3 to the http:/bar endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service2 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service3 side. Physically there are 2 spans but they form 1 logical span related to an RPC call. + + +2 spans come from the RPC call from service2 to service4 to the http:/baz endpoint. It has the Client Sent (CS) +and Client Received (CR) annotations on service2 side. It also has Server Received (SR) and Server Sent (SS) annotations +on the service4 side. Physically there are 2 spans but they form 1 logical span related to an RPC call. + + +So if we count the physical spans we have 1 from http:/start, 2 from service1 calling service2, 2 form service2 +calling service3 and 2 from service2 calling service4. Altogether 7 spans. +Logically we see the information of Total Spans: 4 because we have 1 span related to the incoming request +to service1 and 3 spans related to RPC calls. +
+
+Visualizing errors +Zipkin allows you to visualize errors in your trace. When an exception was thrown and wasn’t caught then we’re +setting proper tags on the span which Zipkin can properly colorize. You could see in the list of traces one + trace that was in red color. That’s because there was an exception thrown. +If you click that trace then you’ll see a similar picture + + + + + +Error Traces + + +Then if you click on one of the spans you’ll see the following + + + + + +Error Traces Info propagation + + +As you can see you can easily see the reason for an error and the whole stacktrace related to it. +
+
+Live examples +
+Click Pivotal Web Services icon to see it live! + + + + +Zipkin deployed on Pivotal Web Services + +
+The dependency graph in Zipkin would look like this: + + + + + +Dependencies + + +
+Click Pivotal Web Services icon to see it live! + + + + +Zipkin deployed on Pivotal Web Services + +
+
+
+Log correlation +When grepping the logs of those four applications by trace id equal to e.g. 2485ec27856c56f4 one would get the following: +service1.log:2016-02-26 11:15:47.561 INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application : Hello from service1. Calling service2 +service2.log:2016-02-26 11:15:47.710 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Hello from service2. Calling service3 and then service4 +service3.log:2016-02-26 11:15:47.895 INFO [service3,2485ec27856c56f4,1210be13194bfe5,true] 68060 --- [nio-8083-exec-1] i.s.c.sleuth.docs.service3.Application : Hello from service3 +service2.log:2016-02-26 11:15:47.924 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Got response from service3 [Hello from service3] +service4.log:2016-02-26 11:15:48.134 INFO [service4,2485ec27856c56f4,1b1845262ffba49d,true] 68061 --- [nio-8084-exec-1] i.s.c.sleuth.docs.service4.Application : Hello from service4 +service2.log:2016-02-26 11:15:48.156 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Got response from service4 [Hello from service4] +service1.log:2016-02-26 11:15:48.182 INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application : Got response from service2 [Hello from service2, response from service3 [Hello from service3] and from service4 [Hello from service4]] +If you’re using a log aggregating tool like Kibana, +Splunk etc. you can order the events that took place. An example of +Kibana would look like this: + + + + + +Log correlation with Kibana + + +If you want to use Logstash here is the Grok pattern for Logstash: +filter { + # pattern matching logback pattern + grok { + match => { "message" => "%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" } + } +} + +If you want to use Grok together with the logs from Cloud Foundry you have to use this pattern: + +filter { + # pattern matching logback pattern + grok { + match => { "message" => "(?m)OUT\s+%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" } + } +} +
+JSON Logback with Logstash +Often you do not want to store your logs in a text file but in a JSON file that Logstash can immediately pick. To do that you have to do the following (for readability +we’re passing the dependencies in the groupId:artifactId:version notation. +Dependencies setup + + +Ensure that Logback is on the classpath (ch.qos.logback:logback-core) + + +Add Logstash Logback encode - example for version 4.6 : net.logstash.logback:logstash-logback-encoder:4.6 + + +Logback setup +Below you can find an example of a Logback configuration (file named logback-spring.xml) that: + + +logs information from the application in a JSON format to a build/${spring.application.name}.json file + + +has commented out two additional appenders - console and standard log file + + +has the same logging pattern as the one presented in the previous section + + +<?xml version="1.0" encoding="UTF-8"?> +<configuration> + <include resource="org/springframework/boot/logging/logback/defaults.xml"/> + ​ + <springProperty scope="context" name="springAppName" source="spring.application.name"/> + <!-- Example for logging into the build folder of your project --> + <property name="LOG_FILE" value="${BUILD_FOLDER:-build}/${springAppName}"/>​ + + <!-- You can override this to have a custom pattern --> + <property name="CONSOLE_LOG_PATTERN" + value="%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}"/> + + <!-- Appender to log to console --> + <appender name="console" class="ch.qos.logback.core.ConsoleAppender"> + <filter class="ch.qos.logback.classic.filter.ThresholdFilter"> + <!-- Minimum logging level to be presented in the console logs--> + <level>DEBUG</level> + </filter> + <encoder> + <pattern>${CONSOLE_LOG_PATTERN}</pattern> + <charset>utf8</charset> + </encoder> + </appender> + + <!-- Appender to log to file -->​ + <appender name="flatfile" class="ch.qos.logback.core.rolling.RollingFileAppender"> + <file>${LOG_FILE}</file> + <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> + <fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.gz</fileNamePattern> + <maxHistory>7</maxHistory> + </rollingPolicy> + <encoder> + <pattern>${CONSOLE_LOG_PATTERN}</pattern> + <charset>utf8</charset> + </encoder> + </appender> + ​ + <!-- Appender to log to file in a JSON format --> + <appender name="logstash" class="ch.qos.logback.core.rolling.RollingFileAppender"> + <file>${LOG_FILE}.json</file> + <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> + <fileNamePattern>${LOG_FILE}.json.%d{yyyy-MM-dd}.gz</fileNamePattern> + <maxHistory>7</maxHistory> + </rollingPolicy> + <encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder"> + <providers> + <timestamp> + <timeZone>UTC</timeZone> + </timestamp> + <pattern> + <pattern> + { + "severity": "%level", + "service": "${springAppName:-}", + "trace": "%X{X-B3-TraceId:-}", + "span": "%X{X-B3-SpanId:-}", + "parent": "%X{X-B3-ParentSpanId:-}", + "exportable": "%X{X-Span-Export:-}", + "pid": "${PID:-}", + "thread": "%thread", + "class": "%logger{40}", + "rest": "%message" + } + </pattern> + </pattern> + </providers> + </encoder> + </appender> + ​ + <root level="INFO"> + <appender-ref ref="console"/> + <!-- uncomment this to have also JSON logs --> + <!--<appender-ref ref="logstash"/>--> + <!--<appender-ref ref="flatfile"/>--> + </root> +</configuration> + +If you’re using a custom logback-spring.xml then you have to pass the spring.application.name in +bootstrap instead of application property file. Otherwise your custom logback file won’t read the property properly. + +
+
+
+Propagating Span Context +The span context is the state that must get propagated to any child Spans across process boundaries. +Part of the Span Context is the Baggage. The trace and span IDs are a required part of the span context. +Baggage is an optional part. +Baggage is a set of key:value pairs stored in the span context. Baggage travels together with the trace +and is attached to every span. Spring Cloud Sleuth will understand that a header is baggage related if the HTTP + header is prefixed with baggage- and for messaging it starts with baggage_. + +There’s currently no limitation of the count or size of baggage items. However, keep in mind that +too many can decrease system throughput or increase RPC latency. In extreme cases, it could crash the app due +to exceeding transport-level message or header capacity. + +Example of setting baggage on a span: +Span initialSpan = this.tracer.createSpan("span"); +initialSpan.setBaggageItem("foo", "bar"); +initialSpan.setBaggageItem("UPPER_CASE", "someValue"); +
+Baggage vs. Span Tags +Baggage travels with the trace (i.e. every child span contains the baggage of its parent). Zipkin has no knowledge of +baggage and will not even receive that information. +Tags are attached to a specific span - they are presented for that particular span only. However you +can search by tag to find the trace, where there exists a span having the searched tag value. +If you want to be able to lookup a span based on baggage, you should add corresponding entry as a tag in the root span. +@Autowired Tracer tracer; + +Span span = tracer.getCurrentSpan(); +String baggageKey = "key"; +String baggageValue = "foo"; +span.setBaggageItem(baggageKey, baggageValue); +tracer.addTag(baggageKey, baggageValue); +
+
+
+
+Adding to the project + +To ensure that your application name is properly displayed in Zipkin + set the spring.application.name property in bootstrap.yml. + +
+Only Sleuth (log correlation) +If you want to profit only from Spring Cloud Sleuth without the Zipkin integration just add +the spring-cloud-starter-sleuth module to your project. + +Maven + +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${release.train.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> + </dependencyManagement> + + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-sleuth</artifactId> + </dependency> + + + + +In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM + + +Add the dependency to spring-cloud-starter-sleuth + + + +Gradle + +dependencyManagement { + imports { + mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}" + } +} + +dependencies { + compile "org.springframework.cloud:spring-cloud-starter-sleuth" +} + + + + +In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM + + +Add the dependency to spring-cloud-starter-sleuth + + +
+
+Sleuth with Zipkin via HTTP +If you want both Sleuth and Zipkin just add the spring-cloud-starter-zipkin dependency. + +Maven + +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${release.train.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> + </dependencyManagement> + + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-zipkin</artifactId> + </dependency> + + + + +In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM + + +Add the dependency to spring-cloud-starter-zipkin + + + +Gradle + +dependencyManagement { + imports { + mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}" + } +} + +dependencies { + compile "org.springframework.cloud:spring-cloud-starter-zipkin" +} + + + + +In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM + + +Add the dependency to spring-cloud-starter-zipkin + + +
+
+Sleuth with Zipkin via RabbitMQ or Kafka +If you want to use RabbitMQ or Kafka instead of http, add the spring-rabbit or spring-kafka +dependencies. The default destination name is zipkin. +Note: spring-cloud-sleuth-stream is deprecated and incompatible with these destinations +If you want Sleuth over RabbitMQ add the spring-cloud-starter-zipkin and spring-rabbit +dependencies. + +Maven + +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${release.train.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> + </dependencyManagement> + + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-zipkin</artifactId> + </dependency> + <dependency> + <groupId>org.springframework.amqp</groupId> + <artifactId>spring-rabbit</artifactId> + </dependency> + + + + +In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM + + +Add the dependency to spring-cloud-starter-zipkin - that way all dependent dependencies will be downloaded + + +To automatically configure rabbit, simply add the spring-rabbit dependency + + + +Gradle + +dependencyManagement { + imports { + mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}" + } +} + +dependencies { + compile "org.springframework.cloud:spring-cloud-starter-zipkin" + compile "org.springframework.amqp:spring-rabbit" +} + + + + +In order not to pick versions by yourself it’s much better if you add the dependency management via +the Spring BOM + + +Add the dependency to spring-cloud-starter-zipkin - that way all dependent dependencies will be downloaded + + +To automatically configure rabbit, simply add the spring-rabbit dependency + + +
+
+ + +Additional resources +Marcin Grzejszczak talking about Spring Cloud Sleuth and Zipkin + +click here to see the video + + +Features + + +Adds trace and span ids to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator. Example logs: +2016-02-02 15:30:57.902 INFO [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ... +2016-02-02 15:30:58.372 ERROR [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ... +2016-02-02 15:31:01.936 INFO [bar,46ab0d418373cbc9,46ab0d418373cbc9,false] 23030 --- [nio-8081-exec-4] ... +notice the [appname,traceId,spanId,exportable] entries from the MDC: + + +spanId - the id of a specific operation that took place + + +appname - the name of the application that logged the span + + +traceId - the id of the latency graph that contains the span + + +exportable - whether the log should be exported to Zipkin or not. When would you like the span not to be +exportable? In the case in which you want to wrap some operation in a Span and have it written to the logs +only. + + + + +Provides an abstraction over common distributed tracing data models: traces, spans (forming a DAG), annotations, +key-value annotations. Loosely based on HTrace, but Zipkin (Dapper) compatible. + + +Sleuth records timing information to aid in latency analysis. Using sleuth, you can pinpoint causes of +latency in your applications. Sleuth is written to not log too much, and to not cause your production application to crash. + + +propagates structural data about your call-graph in-band, and the rest out-of-band. + + +includes opinionated instrumentation of layers such as HTTP + + +includes sampling policy to manage volume + + +can report to a Zipkin system for query and visualization + + + + +Instruments common ingress and egress points from Spring applications (servlet filter, async endpoints, +rest template, scheduled actions, message channels, zuul filters, feign client). + + +Sleuth includes default logic to join a trace across http or messaging boundaries. For example, http propagation +works via Zipkin-compatible request headers. This propagation logic is defined and customized via +SpanInjector and SpanExtractor implementations. + + +Sleuth gives you the possibility to propagate context (also known as baggage) between processes. That means that if you set on a Span +a baggage element then it will be sent downstream either via HTTP or messaging to other processes. + + +Provides a way to create / continue spans and add tags and logs via annotations. + + +Provides simple metrics of accepted / dropped spans. + + +If spring-cloud-sleuth-zipkin is on the classpath then the app will generate and collect Zipkin-compatible traces. +By default it sends them via HTTP to a Zipkin server on localhost (port 9411). +Configure the location of the service using spring.zipkin.baseUrl. + + +If you depend on spring-rabbit or spring-kafka your app will send traces to a broker instead of http. + + +Note: spring-cloud-sleuth-stream is deprecated and should no longer be used. + + + + + +If using Zipkin, configure the percentage of spans exported using spring.sleuth.sampler.percentage +(default 0.1, i.e. 10%). Otherwise you might think that Sleuth is not working cause it’s omitting some spans. + + +the SLF4J MDC is always set and logback users will immediately see the trace and span ids in logs per the example + above. Other logging systems have to configure their own formatter to get the same result. The default is + logging.pattern.level set to %5p [${spring.zipkin.service.name:${spring.application.name:-}},%X{X-B3-TraceId:-},%X{X-B3-SpanId:-},%X{X-Span-Export:-}] + (this is a Spring Boot feature for logback users). + This means that if you’re not using SLF4J this pattern WILL NOT be automatically applied. + + + +Sampling +In distributed tracing the data volumes can be very high so sampling +can be important (you usually don’t need to export all spans to get a +good picture of what is happening). Spring Cloud Sleuth has a +Sampler strategy that you can implement to take control of the +sampling algorithm. Samplers do not stop span (correlation) ids from +being generated, but they do prevent the tags and events being +attached and exported. By default you get a strategy that continues to +trace if a span is already active, but new ones are always marked as +non-exportable. If all your apps run with this sampler you will see +traces in logs, but not in any remote store. For testing the default +is often enough, and it probably is all you need if you are only using +the logs (e.g. with an ELK aggregator). If you are exporting span data +to Zipkin or Spring Cloud Stream, there is also an AlwaysSampler +that exports everything and a PercentageBasedSampler that samples a +fixed fraction of spans. + +the PercentageBasedSampler is the default if you are using +spring-cloud-sleuth-zipkin or spring-cloud-sleuth-stream. You can +configure the exports using spring.sleuth.sampler.percentage. The passed +value needs to be a double from 0.0 to 1.0 so it’s not a percentage. +For backwards compatibility reasons we’re not changing the property name. + +A sampler can be installed just by creating a bean definition, e.g: +@Bean +public Sampler defaultSampler() { + return new AlwaysSampler(); +} + +You can set the HTTP header X-B3-Flags to 1 or when doing messaging you can +set spanFlags header to 1. Then the current span will be forced to be exportable +regardless of the sampling decision. + + + +Instrumentation +Spring Cloud Sleuth instruments all your Spring application +automatically, so you shouldn’t have to do anything to activate +it. The instrumentation is added using a variety of technologies +according to the stack that is available, e.g. for a servlet web +application we use a Filter, and for Spring Integration we use +ChannelInterceptors. +You can customize the keys used in span tags. To limit the volume of +span data, by default an HTTP request will be tagged only with a +handful of metadata like the status code, host and URL. You can add +request headers by configuring spring.sleuth.keys.http.headers (a +list of header names). + +Remember that tags are only collected and exported if there is a +Sampler that allows it (by default there is not, so there is no +danger of accidentally collecting too much data without configuring +something). + + +Currently the instrumentation in Spring Cloud Sleuth is eager - it means that +we’re actively trying to pass the tracing context between threads. Also timing events +are captured even when sleuth isn’t exporting data to a tracing system. +This approach may change in the future towards being lazy on this matter. + + + +Span lifecycle +You can do the following operations on the Span by means of org.springframework.cloud.sleuth.Tracer interface: + + +start - when you start a span its name is assigned and start timestamp is recorded. + + +close - the span gets finished (the end time of the span is recorded) and if +the span is exportable then it will be eligible for collection to Zipkin. +The span is also removed from the current thread. + + +continue - a new instance of span will be created whereas it will be a copy of the +one that it continues. + + +detach - the span doesn’t get stopped or closed. It only gets removed from the current thread. + + +create with explicit parent - you can create a new span and set an explicit parent to it + + + +Spring creates the instance of Tracer for you. In order to use it all you need is to just autowire it. + +
+Creating and closing spans +You can manually create spans by using the Tracer interface. +// Start a span. If there was a span present in this thread it will become +// the `newSpan`'s parent. +Span newSpan = this.tracer.createSpan("calculateTax"); +try { + // ... + // You can tag a span + this.tracer.addTag("taxValue", taxValue); + // ... + // You can log an event on a span + newSpan.logEvent("taxCalculated"); +} finally { + // Once done remember to close the span. This will allow collecting + // the span to send it to Zipkin + this.tracer.close(newSpan); +} +In this example we could see how to create a new instance of span. Assuming that there already +was a span present in this thread then it would become the parent of that span. + +Always clean after you create a span! Don’t forget to close a span if you want to send it to Zipkin. + + +If your span contains a name greater than 50 chars, then that name will +be truncated to 50 chars. Your names have to be explicit and concrete. Big names lead to +latency issues and sometimes even thrown exceptions. + +
+
+Continuing spans +Sometimes you don’t want to create a new span but you want to continue one. Example of such a +situation might be (of course it all depends on the use-case): + + +AOP - If there was already a span created before an aspect was reached then you might not want to create a new span. + + +Hystrix - executing a Hystrix command is most likely a logical part of the current processing. It’s in fact +only a technical implementation detail that you wouldn’t necessarily want to reflect in tracing as a separate being. + + +The continued instance of span is equal to the one that it continues: +Span continuedSpan = this.tracer.continueSpan(spanToContinue); +assertThat(continuedSpan).isEqualTo(spanToContinue); +To continue a span you can use the Tracer interface. +// let's assume that we're in a thread Y and we've received +// the `initialSpan` from thread X +Span continuedSpan = this.tracer.continueSpan(initialSpan); +try { + // ... + // You can tag a span + this.tracer.addTag("taxValue", taxValue); + // ... + // You can log an event on a span + continuedSpan.logEvent("taxCalculated"); +} finally { + // Once done remember to detach the span. That way you'll + // safely remove it from the current thread without closing it + this.tracer.detach(continuedSpan); +} + +Always clean after you create a span! Don’t forget to detach a span if some work was done started in one + thread (e.g. thread X) and it’s waiting for other threads (e.g. Y, Z) to finish. + Then the spans in the threads Y, Z should be detached at the end of their work. When the results are collected + the span in thread X should be closed. + +
+
+Creating spans with an explicit parent +There is a possibility that you want to start a new span and provide an explicit parent of that span. +Let’s assume that the parent of a span is in one thread and you want to start a new span in another thread. The +startSpan method of the Tracer interface is the method you are looking for. +// let's assume that we're in a thread Y and we've received +// the `initialSpan` from thread X. `initialSpan` will be the parent +// of the `newSpan` +Span newSpan = this.tracer.createSpan("calculateCommission", initialSpan); +try { + // ... + // You can tag a span + this.tracer.addTag("commissionValue", commissionValue); + // ... + // You can log an event on a span + newSpan.logEvent("commissionCalculated"); +} finally { + // Once done remember to close the span. This will allow collecting + // the span to send it to Zipkin. The tags and events set on the + // newSpan will not be present on the parent + this.tracer.close(newSpan); +} + +After having created such a span remember to close it. Otherwise you will see a lot of warnings in your logs + related to the fact that you have a span present in the current thread other than the one you’re trying to close. + What’s worse your spans won’t get closed properly thus will not get collected to Zipkin. + +
+ + +Naming spans +Picking a span name is not a trivial task. Span name should depict an operation name. The name should +be low cardinality (e.g. not include identifiers). +Since there is a lot of instrumentation going on some of the span names will be +artificial like: + + +controller-method-name when received by a Controller with a method name conrollerMethodName + + +async for asynchronous operations done via wrapped Callable and Runnable. + + +@Scheduled annotated methods will return the simple name of the class. + + +Fortunately, for the asynchronous processing you can provide explicit naming. +
+@SpanName annotation +You can name the span explicitly via the @SpanName annotation. +@SpanName("calculateTax") +class TaxCountingRunnable implements Runnable { + + @Override public void run() { + // perform logic + } +} +In this case, when processed in the following manner: +Runnable runnable = new TraceRunnable(tracer, spanNamer, new TaxCountingRunnable()); +Future<?> future = executorService.submit(runnable); +// ... some additional logic ... +future.get(); +The span will be named calculateTax. +
+
+toString() method +It’s pretty rare to create separate classes for Runnable or Callable. Typically one creates an anonymous +instance of those classes. You can’t annotate such classes thus to override that, if there is no @SpanName annotation present, +we’re checking if the class has a custom implementation of the toString() method. +So executing such code: +Runnable runnable = new TraceRunnable(tracer, spanNamer, new Runnable() { + @Override public void run() { + // perform logic + } + + @Override public String toString() { + return "calculateTax"; + } +}); +Future<?> future = executorService.submit(runnable); +// ... some additional logic ... +future.get(); +will lead in creating a span named calculateTax. +
+ + +Managing spans with annotations +
+Rationale +The main arguments for this features are + + +api-agnostic means to collaborate with a span + + +use of annotations allows users to add to a span with no library dependency on a span api. +This allows Sleuth to change its core api less impact to user code. + + + + +reduced surface area for basic span operations. + + +without this feature one has to use the span api, which has lifecycle commands that +could be used incorrectly. By only exposing scope, tag and log functionality, users can +collaborate without accidentally breaking span lifecycle. + + + + +collaboration with runtime generated code + + +with libraries such as Spring Data / Feign the implementations of interfaces are generated +at runtime thus span wrapping of objects was tedious. Now you can provide annotations + over interfaces and arguments of those interfaces + + + + +
+
+Creating new spans +If you really don’t want to take care of creating local spans manually you can profit from the +@NewSpan annotation. Also we give you the @SpanTag annotation to add tags in an automated +fashion. +Let’s look at some examples of usage. +@NewSpan +void testMethod(); +Annotating the method without any parameter will lead to a creation of a new span whose name +will be equal to annotated method name. +@NewSpan("customNameOnTestMethod4") +void testMethod4(); +If you provide the value in the annotation (either directly or via the name parameter) then +the created span will have the name as the provided value. +// method declaration +@NewSpan(name = "customNameOnTestMethod5") +void testMethod5(@SpanTag("testTag") String param); + +// and method execution +this.testBean.testMethod5("test"); +You can combine both the name and a tag. Let’s focus on the latter. In this case whatever the value of +the annotated method’s parameter runtime value will be - that will be the value of the tag. In our sample +the tag key will be testTag and the tag value will be test. +@NewSpan(name = "customNameOnTestMethod3") +@Override +public void testMethod3() { +} +You can place the @NewSpan annotation on both the class and an interface. If you override the +interface’s method and provide a different value of the @NewSpan annotation then the most +concrete one wins (in this case customNameOnTestMethod3 will be set). +
+
+Continuing spans +If you want to just add tags and annotations to an existing span it’s enough +to use the @ContinueSpan annotation as presented below. Note that in contrast +with the @NewSpan annotation you can also add logs via the log parameter: +// method declaration +@ContinueSpan(log = "testMethod11") +void testMethod11(@SpanTag("testTag11") String param); + +// method execution +this.testBean.testMethod11("test"); +That way the span will get continued and: + + +logs with name testMethod11.before and testMethod11.after will be created + + +if an exception will be thrown a log testMethod11.afterFailure will also be created + + +tag with key testTag11 and value test will be created + + +
+
+More advanced tag setting +There are 3 different ways to add tags to a span. All of them are controlled by the SpanTag annotation. +Precedence is: + + +try with the bean of TagValueResolver type and provided name + + +if one hasn’t provided the bean name, try to evaluate an expression. We’re searching for a TagValueExpressionResolver bean. +The default implementation uses SPEL expression resolution. If we do not find any expression to evaluate, return the toString() +value of the parameter. +IMPORTANT You can only reference properties from the SPEL expression. Method execution is not allowed due to security constraints. + + +if one hasn’t provided any expression to evaluate just return a toString() value of the parameter + + +
+Custom extractor +The value of the tag for following method will be computed by an implementation of TagValueResolver interface. +Its class name has to be passed as the value of the resolver attribute. +Having such an annotated method: +@NewSpan +public void getAnnotationForTagValueResolver(@SpanTag(key = "test", resolver = TagValueResolver.class) String test) { +} +and such a TagValueResolver bean implementation +@Bean(name = "myCustomTagValueResolver") +public TagValueResolver tagValueResolver() { + return parameter -> "Value from myCustomTagValueResolver"; +} +Will lead to setting of a tag value equal to Value from myCustomTagValueResolver. +
+
+Resolving expressions for value +Having such an annotated method: +@NewSpan +public void getAnnotationForTagValueExpression(@SpanTag(key = "test", expression = "'hello' + ' characters'") String test) { +} +and no custom implementation of a TagValueExpressionResolver will lead to evaluation of the SPEL expression and a tag with value 4 characters will be set on the span. +If you want to use some other expression resolution mechanism you can create your own implementation +of the bean. +
+
+Using toString method +Having such an annotated method: +@NewSpan +public void getAnnotationForArgumentToString(@SpanTag("test") Long param) { +} +if executed with a value of 15 will lead to setting of a tag with a String value of "15". +
+
+ + +Customizations +Thanks to the SpanInjector and SpanExtractor you can customize the way spans +are created and propagated. +There are currently two built-in ways to pass tracing information between processes: + + +via Spring Integration + + +via HTTP + + +Span ids are extracted from Zipkin-compatible (B3) headers (either Message +or HTTP headers), to start or join an existing trace. Trace information is +injected into any outbound requests so the next hop can extract them. +The default way of coding tracing context is done via the b3 header that contains the +traceId-spanId-sampled notation (e.g. 0000000000000005-0000000000000004-1). +For backward compatibility, if the b3 header is not present, we also check if +X-B3 entries are present, and retrieve tracing context from there e.g. +(X-B3-TraceId: 0000000000000005, X-B3-SpanId: 0000000000000004, X-B3-Sampled: 1). +The key change in comparison to the previous versions of Sleuth is that Sleuth is implementing +the Open Tracing’s TextMap notion. In Sleuth it’s called SpanTextMap. Basically the idea +is that any means of communication (e.g. message, http request, etc.) can be abstracted via +a SpanTextMap. This abstraction defines how one can insert data into the carrier and +how to retrieve it from there. Thanks to this if you want to instrument a new HTTP library +that uses a FooRequest as a mean of sending HTTP requests then you have to create an +implementation of a SpanTextMap that delegates calls to FooRequest in terms of retrieval +and insertion of HTTP headers. +
+Spring Integration +For Spring Integration there are 2 interfaces responsible for creation of a Span from a Message. +These are: + + +MessagingSpanTextMapExtractor + + +MessagingSpanTextMapInjector + + +You can override them by providing your own implementation. +
+
+HTTP +For HTTP there are 2 interfaces responsible for creation of a Span from a Message. +These are: + + +HttpSpanExtractor + + +HttpSpanInjector + + +You can override them by providing your own implementation. +
+
+Example +Let’s assume that instead of the standard Zipkin compatible tracing HTTP header names +you have + + +for trace id - correlationId + + +for span id - mySpanId + + +This is a an example of a SpanExtractor +static class CustomHttpSpanExtractor implements HttpSpanExtractor { + + @Override public Span joinTrace(SpanTextMap carrier) { + Map<String, String> map = TextMapUtil.asMap(carrier); + long traceId = Span.hexToId(map.get("correlationid")); + long spanId = Span.hexToId(map.get("myspanid")); + // extract all necessary headers + Span.SpanBuilder builder = Span.builder().traceId(traceId).spanId(spanId); + // build rest of the Span + return builder.build(); + } +} + +static class CustomHttpSpanInjector implements HttpSpanInjector { + + @Override + public void inject(Span span, SpanTextMap carrier) { + carrier.put("correlationId", span.traceIdString()); + carrier.put("mySpanId", Span.idToHex(span.getSpanId())); + } +} +And you could register it like this: +@Bean +HttpSpanInjector customHttpSpanInjector() { + return new CustomHttpSpanInjector(); +} + +@Bean +HttpSpanExtractor customHttpSpanExtractor() { + return new CustomHttpSpanExtractor(); +} +Spring Cloud Sleuth does not add trace/span related headers to the Http Response for security reasons. If you need the headers then a custom SpanInjector +that injects the headers into the Http Response and a Servlet filter which makes use of this can be added the following way: +static class CustomHttpServletResponseSpanInjector extends ZipkinHttpSpanInjector { + + @Override + public void inject(Span span, SpanTextMap carrier) { + super.inject(span, carrier); + carrier.put(Span.TRACE_ID_NAME, span.traceIdString()); + carrier.put(Span.SPAN_ID_NAME, Span.idToHex(span.getSpanId())); + } +} + +static class HttpResponseInjectingTraceFilter extends GenericFilterBean { + + private final Tracer tracer; + private final HttpSpanInjector spanInjector; + + public HttpResponseInjectingTraceFilter(Tracer tracer, HttpSpanInjector spanInjector) { + this.tracer = tracer; + this.spanInjector = spanInjector; + } + + @Override + public void doFilter(ServletRequest request, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { + HttpServletResponse response = (HttpServletResponse) servletResponse; + Span currentSpan = this.tracer.getCurrentSpan(); + this.spanInjector.inject(currentSpan, new HttpServletResponseTextMap(response)); + filterChain.doFilter(request, response); + } + + class HttpServletResponseTextMap implements SpanTextMap { + + private final HttpServletResponse delegate; + + HttpServletResponseTextMap(HttpServletResponse delegate) { + this.delegate = delegate; + } + + @Override + public Iterator<Map.Entry<String, String>> iterator() { + Map<String, String> map = new HashMap<>(); + for (String header : this.delegate.getHeaderNames()) { + map.put(header, this.delegate.getHeader(header)); + } + return map.entrySet().iterator(); + } + + @Override + public void put(String key, String value) { + this.delegate.addHeader(key, value); + } + } +} +And you could register them like this: +@Bean HttpSpanInjector customHttpServletResponseSpanInjector() { + return new CustomHttpServletResponseSpanInjector(); +} + +@Bean +HttpResponseInjectingTraceFilter responseInjectingTraceFilter(Tracer tracer) { + return new HttpResponseInjectingTraceFilter(tracer, customHttpServletResponseSpanInjector()); +} +
+
+TraceFilter +You can also modify the behaviour of the TraceFilter - the component that is responsible +for processing the input HTTP request and adding tags basing on the HTTP response. You can customize +the tags, or modify the response headers by registering your own instance of the TraceFilter bean. +In the following example we will register the TraceFilter bean and we will add the +ZIPKIN-TRACE-ID response header containing the current Span’s trace id. Also we will +add to the Span a tag with key custom and a value tag. +@Bean +TraceFilter myTraceFilter(BeanFactory beanFactory, final Tracer tracer) { + return new TraceFilter(beanFactory) { + @Override protected void addResponseTags(HttpServletResponse response, + Throwable e) { + // execute the default behaviour + super.addResponseTags(response, e); + // for readability we're returning trace id in a hex form + response.addHeader("ZIPKIN-TRACE-ID", + Span.idToHex(tracer.getCurrentSpan().getTraceId())); + // we can also add some custom tags + tracer.addTag("custom", "tag"); + } + }; +} +To change the order of TraceFilter registration, please set the +spring.sleuth.web.filter-order property. +
+
+Custom SA tag in Zipkin +Sometimes you want to create a manual Span that will wrap a call to an external service which is not instrumented. +What you can do is to create a span with the peer.service tag that will contain a value of the service that you want to call. +Below you can see an example of a call to Redis that is wrapped in such a span. +org.springframework.cloud.sleuth.Span newSpan = tracer.createSpan("redis"); +try { + newSpan.tag("redis.op", "get"); + newSpan.tag("lc", "redis"); + newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_SEND); + // call redis service e.g + // return (SomeObj) redisTemplate.opsForHash().get("MYHASH", someObjKey); +} finally { + newSpan.tag("peer.service", "redisService"); + newSpan.tag("peer.ipv4", "1.2.3.4"); + newSpan.tag("peer.port", "1234"); + newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_RECV); + tracer.close(newSpan); +} + +Remember not to add both peer.service tag and the SA tag! You have to add only peer.service. + +
+
+Custom service name +By default Sleuth assumes that when you send a span to Zipkin, you want the span’s service name + to be equal to spring.application.name value. That’s not always the case though. There + are situations in which you want to explicitly provide a different service name for all spans coming + from your application. To achieve that it’s enough to just pass the following property + to your application to override that value (example for foo service name): +spring.zipkin.service.name: foo +
+
+Customization of reported spans +Before reporting spans to e.g. Zipkin you can be interested in modifying that span in some way. + You can achieve that by using the SpanAdjuster interface. +Example of usage: +In Sleuth we’re generating spans with a fixed name. Some users want to modify the name depending on values +of tags. Implementation of the SpanAdjuster interface can be used to alter that name. Example: +@Bean +SpanAdjuster customSpanAdjuster() { + return span -> span.toBuilder().name(scrub(span.getName())).build(); +} +This will lead in changing the name of the reported span just before it gets sent to Zipkin. + +Your SpanReporter should inject the SpanAdjuster and + allow span manipulation before the actual reporting is done. + +
+
+Host locator +In order to define the host that is corresponding to a particular span we need to resolve the host name +and port. The default approach is to take it from server properties. If those for some reason are not set +then we’re trying to retrieve the host name from the network interfaces. +If you have the discovery client enabled and prefer to retrieve the host address from the registered +instance in a service registry then you have to set the property (it’s applicable for both HTTP and +Stream based span reporting). +spring.zipkin.locator.discovery.enabled: true +
+ + +Sending spans to Zipkin + +spring-cloud-sleuth-stream is deprecated and should no longer be used. +If spring-cloud-sleuth-zipkin is on the classpath then the app will generate and collect Zipkin-compatible traces. +By default it sends them via HTTP to a Zipkin server on localhost (port 9411). If you depend +on spring-rabbit or spring-kafka your app will send traces to a broker instead of http. + +By default if you add spring-cloud-starter-zipkin as a dependency to your project, +when the span is closed, it will be sent to Zipkin over HTTP. The communication +is asynchronous. You can configure the URL by setting the spring.zipkin.baseUrl +property as follows: +spring.zipkin.baseUrl: https://192.168.99.100:9411/ +If you want to find Zipkin via service discovery it’s enough to pass the +Zipkin’s service id inside the URL. If you want to disable this feature +just set spring.zipkin.discoveryClientEnabled to false. +Example for `zipkinserver service id: +spring.zipkin.baseUrl: http://zipkinserver/ +When this Discovery Client feature is enabled, Sleuth uses +LoadBalancerClient to find the URL of the Zipkin Server. It means +that you can set up the load balancing configuration e.g. via Ribbon. +zipkinserver: + ribbon: + ListOfServers: host1,host2 +If you have web, rabbit or kafka together on the classpath, you might need +to pick the means by which you would like to send spans to zipkin. To do that +just set either web, rabbit or kafka to the spring.zipkin.sender.type property. +Example for web: +spring.zipkin.sender.type: web +To customize the RestTemplate that sends spans to Zipkin via HTTP, you can register +the ZipkinRestTemplateCustomizer bean. +@Configuration +class MyConfig { + @Bean ZipkinRestTemplateCustomizer myCustomizer() { + return new ZipkinRestTemplateCustomizer() { + @Override + void customize(RestTemplate restTemplate) { + // customize the RestTemplate + } + }; + } +} +If, however, you would like to control the full process of creating the RestTemplate +object, you will have to create a bean of zipkin2.reporter.Sender type. + @Bean Sender myRestTemplateSender(ZipkinProperties zipkin, + ZipkinRestTemplateCustomizer zipkinRestTemplateCustomizer) { + RestTemplate restTemplate = mySuperCustomRestTemplate(); + zipkinRestTemplateCustomizer.customize(restTemplate); + return myCustomSender(zipkin, restTemplate); + } + + +Span Data as Messages +You can accumulate and send span data over +Spring Cloud Stream by +including the spring-cloud-sleuth-stream jar as a dependency, and +adding a Channel Binder implementation +(e.g. spring-cloud-starter-stream-rabbit for RabbitMQ or +spring-cloud-starter-stream-kafka for Kafka). This will +automatically turn your app into a producer of messages with payload +type Spans. The channel name to which the spans will be sent +is called sleuth. +
+Zipkin Consumer + +spring-cloud-sleuth-zipkin-stream is deprecated and should no longer be used. +Please use the OpenZipkin’s Zipkin server and set the environment variables +as presented here for rabbit (Zipkin 2.4.6) +or here for kafka (Zipkin 2.4.6) + +There is a special convenience annotation for setting up a message consumer +for the Span data and pushing it into a Zipkin SpanStore. This application +@SpringBootApplication +@EnableZipkinStreamServer +public class Consumer { + public static void main(String[] args) { + SpringApplication.run(Consumer.class, args); + } +} +will listen for the Span data on whatever transport you provide via a +Spring Cloud Stream Binder (e.g. include +spring-cloud-starter-stream-rabbit for RabbitMQ, and similar +starters exist for Redis and Kafka). If you add the following UI dependency +<groupId>io.zipkin.java</groupId> +<artifactId>zipkin-autoconfigure-ui</artifactId> +Then you’ll have your app a +Zipkin server, which hosts +the UI and api on port 9411. +The default SpanStore is in-memory (good for demos and getting +started quickly). For a more robust solution you can add MySQL and +spring-boot-starter-jdbc to your classpath and enable the JDBC +SpanStore via configuration, e.g.: +spring: + rabbitmq: + host: ${RABBIT_HOST:localhost} + datasource: + schema: classpath:/mysql.sql + url: jdbc:mysql://${MYSQL_HOST:localhost}/test + username: root + password: root +# Switch this on to create the schema on startup: + initialize: true + continueOnError: true + sleuth: + enabled: false +zipkin: + storage: + type: mysql + +The @EnableZipkinStreamServer is also annotated with +@EnableZipkinServer so the process will also expose the standard +Zipkin server endpoints for collecting spans over HTTP, and for +querying in the Zipkin Web UI. + +
+
+Custom Consumer +A custom consumer can also easily be implemented using +spring-cloud-sleuth-stream and binding to the SleuthSink. Example: +@EnableBinding(SleuthSink.class) +@SpringBootApplication(exclude = SleuthStreamAutoConfiguration.class) +@MessageEndpoint +public class Consumer { + + @ServiceActivator(inputChannel = SleuthSink.INPUT) + public void sink(Spans input) throws Exception { + // ... process spans + } +} + +the sample consumer application above explicitly excludes +SleuthStreamAutoConfiguration so it doesn’t send messages to itself, +but this is optional (you might actually want to trace requests into +the consumer app). + +In order to customize the polling mechanism you can create a bean of PollerMetadata type +with name equal to StreamSpanReporter.POLLER. Here you can find an example of such a configuration. +@Configuration +public static class CustomPollerConfiguration { + + @Bean(name = StreamSpanReporter.POLLER) + PollerMetadata customPoller() { + PollerMetadata poller = new PollerMetadata(); + poller.setMaxMessagesPerPoll(500); + poller.setTrigger(new PeriodicTrigger(5000L)); + return poller; + } +} +
+ + +Metrics +Currently Spring Cloud Sleuth registers very simple metrics related to spans. +It’s using the Spring Boot’s metrics support +to calculate the number of accepted and dropped spans. Each time a span gets +sent to Zipkin the number of accepted spans will increase. If there’s an error then +the number of dropped spans will get increased. + + +Integrations +
+Runnable and Callable +If you’re wrapping your logic in Runnable or Callable it’s enough to wrap those classes in their Sleuth representative. +Example for Runnable: +Runnable runnable = new Runnable() { + @Override + public void run() { + // do some work + } + + @Override + public String toString() { + return "spanNameFromToStringMethod"; + } +}; +// Manual `TraceRunnable` creation with explicit "calculateTax" Span name +Runnable traceRunnable = new TraceRunnable(tracer, spanNamer, runnable, "calculateTax"); +// Wrapping `Runnable` with `Tracer`. The Span name will be taken either from the +// `@SpanName` annotation or from `toString` method +Runnable traceRunnableFromTracer = tracer.wrap(runnable); +Example for Callable: +Callable<String> callable = new Callable<String>() { + @Override + public String call() throws Exception { + return someLogic(); + } + + @Override + public String toString() { + return "spanNameFromToStringMethod"; + } +}; +// Manual `TraceCallable` creation with explicit "calculateTax" Span name +Callable<String> traceCallable = new TraceCallable<>(tracer, spanNamer, callable, "calculateTax"); +// Wrapping `Callable` with `Tracer`. The Span name will be taken either from the +// `@SpanName` annotation or from `toString` method +Callable<String> traceCallableFromTracer = tracer.wrap(callable); +That way you will ensure that a new Span is created and closed for each execution. +
+
+Hystrix +
+Custom Concurrency Strategy +We’re registering a custom HystrixConcurrencyStrategy +that wraps all Callable instances into their Sleuth representative - +the TraceCallable. The strategy either starts or continues a span depending on the fact whether tracing was already going +on before the Hystrix command was called. To disable the custom Hystrix Concurrency Strategy set the spring.sleuth.hystrix.strategy.enabled to false. +
+
+Manual Command setting +Assuming that you have the following HystrixCommand: +HystrixCommand<String> hystrixCommand = new HystrixCommand<String>(setter) { + @Override + protected String run() throws Exception { + return someLogic(); + } +}; +In order to pass the tracing information you have to wrap the same logic in the Sleuth version of the HystrixCommand which is the +TraceCommand: +TraceCommand<String> traceCommand = new TraceCommand<String>(tracer, traceKeys, setter) { + @Override + public String doRun() throws Exception { + return someLogic(); + } +}; +
+
+
+RxJava +We’re registering a custom RxJavaSchedulersHook +that wraps all Action0 instances into their Sleuth representative - +the TraceAction. The hook either starts or continues a span depending on the fact whether tracing was already going +on before the Action was scheduled. To disable the custom RxJavaSchedulersHook set the spring.sleuth.rxjava.schedulers.hook.enabled to false. +You can define a list of regular expressions for thread names, for which you don’t want a Span to be created. Just provide a comma separated list +of regular expressions in the spring.sleuth.rxjava.schedulers.ignoredthreads property. +
+
+HTTP integration +Features from this section can be disabled by providing the spring.sleuth.web.enabled property with value equal to false. +
+HTTP Filter +Via the TraceFilter all sampled incoming requests result in creation of a Span. That Span’s name is http: + the path to which + the request was sent. E.g. if the request was sent to /foo/bar then the name will be http:/foo/bar. You can configure which URIs you would + like to skip via the spring.sleuth.web.skipPattern property. If you have ManagementServerProperties on classpath then + its value of contextPath gets appended to the provided skip pattern. +
+
+HandlerInterceptor +Since we want the span names to be precise we’re using a TraceHandlerInterceptor that either wraps an + existing HandlerInterceptor or is added directly to the list of existing HandlerInterceptors. The + TraceHandlerInterceptor adds a special request attribute to the given HttpServletRequest. If the + the TraceFilter doesn’t see this attribute set it will create a "fallback" span which is an additional + span created on the server side so that the trace is presented properly in the UI. Seeing that most likely + signifies that there is a missing instrumentation. In that case please file an issue in Spring Cloud Sleuth. +
+
+Async Servlet support +If your controller returns a Callable or a WebAsyncTask Spring Cloud Sleuth will continue the existing span instead of creating a new one. +
+
+
+HTTP client integration +
+Synchronous Rest Template +We’re injecting a RestTemplate interceptor that ensures that all the tracing information is passed to the requests. Each time a +call is made a new Span is created. It gets closed upon receiving the response. In order to block the synchronous RestTemplate features +just set spring.sleuth.web.client.enabled to false. + +You have to register RestTemplate as a bean so that the interceptors will get injected. +If you create a RestTemplate instance with a new keyword then the instrumentation WILL NOT work. + +
+
+Asynchronous Rest Template + +A traced version of an AsyncRestTemplate bean is registered for you out of the box. If you +have your own bean you have to wrap it in a TraceAsyncRestTemplate representation. The best solution +is to only customize the ClientHttpRequestFactory and / or AsyncClientHttpRequestFactory. +If you have your own AsyncRestTemplate and you don’t wrap it your calls WILL NOT GET TRACED. + +Custom instrumentation is set to create and close Spans upon sending and receiving requests. You can customize the ClientHttpRequestFactory +and the AsyncClientHttpRequestFactory by registering your beans. Remember to use tracing compatible implementations (e.g. don’t forget to +wrap ThreadPoolTaskScheduler in a TraceAsyncListenableTaskExecutor). Example of custom request factories: +@EnableAutoConfiguration +@Configuration +public static class TestConfiguration { + + @Bean + ClientHttpRequestFactory mySyncClientFactory() { + return new MySyncClientHttpRequestFactory(); + } + + @Bean + AsyncClientHttpRequestFactory myAsyncClientFactory() { + return new MyAsyncClientHttpRequestFactory(); + } +} +To block the AsyncRestTemplate features set spring.sleuth.web.async.client.enabled to false. +To disable creation of the default TraceAsyncClientHttpRequestFactoryWrapper set spring.sleuth.web.async.client.factory.enabled +to false. If you don’t want to create AsyncRestClient at all set spring.sleuth.web.async.client.template.enabled to false. +
+Multiple Asynchronous Rest Templates +Sometimes you need to use multiple implementations of Asynchronous Rest Template. In the following snippet you +can see an example of how to set up such a custom AsyncRestTemplate. +@Configuration +@EnableAutoConfiguration +static class Config { + @Autowired Tracer tracer; + @Autowired HttpTraceKeysInjector httpTraceKeysInjector; + @Autowired HttpSpanInjector spanInjector; + + @Bean(name = "customAsyncRestTemplate") + public AsyncRestTemplate traceAsyncRestTemplate(@Qualifier("customHttpRequestFactoryWrapper") + TraceAsyncClientHttpRequestFactoryWrapper wrapper, ErrorParser errorParser) { + return new TraceAsyncRestTemplate(wrapper, this.tracer, errorParser); + } + + @Bean(name = "customHttpRequestFactoryWrapper") + public TraceAsyncClientHttpRequestFactoryWrapper traceAsyncClientHttpRequestFactory() { + return new TraceAsyncClientHttpRequestFactoryWrapper(this.tracer, + this.spanInjector, + asyncClientFactory(), + clientHttpRequestFactory(), + this.httpTraceKeysInjector); + } + + private ClientHttpRequestFactory clientHttpRequestFactory() { + ClientHttpRequestFactory clientHttpRequestFactory = new CustomClientHttpRequestFactory(); + //CUSTOMIZE HERE + return clientHttpRequestFactory; + } + + private AsyncClientHttpRequestFactory asyncClientFactory() { + AsyncClientHttpRequestFactory factory = new CustomAsyncClientHttpRequestFactory(); + //CUSTOMIZE HERE + return factory; + } +} +
+
+
+Traverson +If you’re using the Traverson library +it’s enough for you to inject a RestTemplate as a bean into your Traverson object. Since RestTemplate +is already intercepted, you will get full support of tracing in your client. Below you can find a pseudo code +of how to do that: +@Autowired RestTemplate restTemplate; + +Traverson traverson = new Traverson(URI.create("http://some/address"), + MediaType.APPLICATION_JSON, MediaType.APPLICATION_JSON_UTF8).setRestOperations(restTemplate); +// use Traverson +
+
+
+Feign +By default Spring Cloud Sleuth provides integration with feign via the TraceFeignClientAutoConfiguration. You can disable it entirely +by setting spring.sleuth.feign.enabled to false. If you do so then no Feign related instrumentation will take place. +Part of Feign instrumentation is done via a FeignBeanPostProcessor. You can disable it by providing the spring.sleuth.feign.processor.enabled equal to false. +If you set it like this then Spring Cloud Sleuth will not instrument any of your custom Feign components. All the default instrumentation +however will be still there. +
+
+Asynchronous communication +
+@Async annotated methods +In Spring Cloud Sleuth we’re instrumenting async related components so that the tracing information is passed between threads. +You can disable this behaviour by setting the value of spring.sleuth.async.enabled to false. +If you annotate your method with @Async then we’ll automatically create a new Span with the following characteristics: + + +if the method is annotated with @SpanName then the value of the annotation will be the Span’s name + + +if the method is not annotated with @SpanName the Span name will be the annotated method name + + +the Span will be tagged with that method’s class name and the method name too + + +
+
+@Scheduled annotated methods +In Spring Cloud Sleuth we’re instrumenting scheduled method execution so that the tracing information is passed between threads. You can disable this behaviour +by setting the value of spring.sleuth.scheduled.enabled to false. +If you annotate your method with @Scheduled then we’ll automatically create a new Span with the following characteristics: + + +the Span name will be the annotated method name + + +the Span will be tagged with that method’s class name and the method name too + + +If you want to skip Span creation for some @Scheduled annotated classes you can set the +spring.sleuth.scheduled.skipPattern with a regular expression that will match the fully qualified name of the +@Scheduled annotated class. + +If you are using spring-cloud-sleuth-stream and spring-cloud-netflix-hystrix-stream together, Span will be created for each Hystrix metrics and sent to Zipkin. This may be annoying. You can prevent this by setting spring.sleuth.scheduled.skipPattern=org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask + +
+
+Executor, ExecutorService and ScheduledExecutorService +We’re providing LazyTraceExecutor, TraceableExecutorService and TraceableScheduledExecutorService. Those implementations +are creating Spans each time a new task is submitted, invoked or scheduled. +Here you can see an example of how to pass tracing information with TraceableExecutorService when working with CompletableFuture: +CompletableFuture<Long> completableFuture = CompletableFuture.supplyAsync(() -> { + // perform some logic + return 1_000_000L; +}, new TraceableExecutorService(executorService, + // 'calculateTax' explicitly names the span - this param is optional + tracer, traceKeys, spanNamer, "calculateTax")); + +Sleuth doesn’t work with parallelStream() out of the box. If you want +to have the tracing information propagated through the stream you have to use the +approach with supplyAsync(…​) as presented above. + +
+Customization of Executors +Sometimes you need to set up a custom instance of the AsyncExecutor. In the following snippet you +can see an example of how to set up such a custom Executor. +@Configuration +@EnableAutoConfiguration +@EnableAsync +static class CustomExecutorConfig extends AsyncConfigurerSupport { + + @Autowired BeanFactory beanFactory; + + @Override public Executor getAsyncExecutor() { + ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); + // CUSTOMIZE HERE + executor.setCorePoolSize(7); + executor.setMaxPoolSize(42); + executor.setQueueCapacity(11); + executor.setThreadNamePrefix("MyExecutor-"); + // DON'T FORGET TO INITIALIZE + executor.initialize(); + return new LazyTraceExecutor(this.beanFactory, executor); + } +} +
+
+
+
+Messaging +Spring Cloud Sleuth integrates with Spring Integration. It creates spans for publish and +subscribe events. To disable Spring Integration instrumentation, set spring.sleuth.integration.enabled to false. +You can provide the spring.sleuth.integration.patterns pattern to explicitly +provide the names of channels that you want to include for tracing. By default all channels +are included. + +When using the Executor to build a Spring Integration IntegrationFlow remember to use the untraced version of the Executor. +Decorating Spring Integration Executor Channel with TraceableExecutorService will cause the spans to be improperly closed. + +
+
+Zuul +We’re registering Zuul filters to propagate the tracing information (the request header is enriched with tracing data). +To disable Zuul support set the spring.sleuth.zuul.enabled property to false. +
+
+Spring Cloud Function +Sleuth works out of the box with Spring Cloud Function. Since functions +might be short living, it’s best to make the Zipkin span reporting synchronous. +Just define a Reporter<Span> bean as presented below: +@Configuration +class ReporterConfiguration { + @Bean + public Reporter<Span> reporter( + SpanMetricReporter spanMetricReporter, + ZipkinProperties zipkin, + Sender sender + ) { + final AsyncReporter<Span> reporter = AsyncReporter.builder(sender) + .queuedMaxSpans(1000) + .messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS) + .metrics(new ReporterMetricsAdapter(spanMetricReporter)) + .build(zipkin.getEncoder()); + return new Reporter<Span>() { + @Override public void report(Span span) { + reporter.report(span); + // make the reporter synchronous + reporter.flush(); + } + }; + } +} +
+ + +Running examples +You can find the running examples deployed in the Pivotal Web Services. Check them out in the following links: + + +Zipkin for apps presented in the samples to the top + + +Zipkin for Brewery on PWS, its Github Code + + + + + +Spring Cloud Consul + +1.3.8.RELEASE +This project provides Consul integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with Consul based components. The +patterns provided include Service Discovery, Control Bus and Configuration. +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker +(Hystrix) are provided by integration with Spring Cloud Netflix. + + +Install Consul +Please see the installation documentation for instructions on how to install Consul. + + +Consul Agent +A Consul Agent client must be available to all Spring Cloud Consul applications. By default, the Agent client is expected to be at localhost:8500. See the Agent documentation for specifics on how to start an Agent client and how to connect to a cluster of Consul Agent Servers. For development, after you have installed consul, you may start a Consul Agent using the following command: +./src/main/bash/local_run_consul.sh +This will start an agent in server mode on port 8500, with the ui available at http://localhost:8500 + + +Service Discovery with Consul +Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Consul provides Service Discovery services via an HTTP API and DNS. Spring Cloud Consul leverages the HTTP API for service registration and discovery. This does not prevent non-Spring Cloud applications from leveraging the DNS interface. Consul Agents servers are run in a cluster that communicates via a gossip protocol and uses the Raft consensus protocol. +
+How to activate +To activate Consul Service Discovery use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-discovery. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train. +
+
+Registering with Consul +When a client registers with Consul, it provides meta-data about itself such as host and port, id, name and tags. An HTTP Check is created by default that Consul hits the /health endpoint every 10 seconds. If the health check fails, the service instance is marked as critical. +Example Consul client: +@SpringBootApplication +@RestController +public class Application { + + @RequestMapping("/") + public String home() { + return "Hello world"; + } + + public static void main(String[] args) { + new SpringApplicationBuilder(Application.class).web(true).run(args); + } + +} +(i.e. utterly normal Spring Boot app). If the Consul client is located somewhere other than localhost:8500, the configuration is required to locate the client. Example: + +application.yml + +spring: + cloud: + consul: + host: localhost + port: 8500 + + + +If you use Spring Cloud Consul Config, the above values will need to be placed in bootstrap.yml instead of application.yml. + +The default service name, instance id and port, taken from the Environment, are ${spring.application.name}, the Spring Context ID and ${server.port} respectively. +To disable the Consul Discovery Client you can set spring.cloud.consul.discovery.enabled to false. +To disable the service registration you can set spring.cloud.consul.discovery.register to false. +
+
+HTTP Health Check +The health check for a Consul instance defaults to "/health", which is the default locations of a useful endpoint in a Spring Boot Actuator application. You need to change these, even for an Actuator application if you use a non-default context path or servlet path (e.g. server.servletPath=/foo) or management endpoint path (e.g. management.context-path=/admin). The interval that Consul uses to check the health endpoint may also be configured. "10s" and "1m" represent 10 seconds and 1 minute respectively. Example: + +application.yml + +spring: + cloud: + consul: + discovery: + healthCheckPath: ${management.context-path}/health + healthCheckInterval: 15s + + +
+Metadata and Consul tags +Consul does not yet support metadata on services. Spring Cloud’s ServiceInstance has a Map<String, String> metadata field. Spring Cloud Consul uses Consul tags to approximate metadata until Consul officially supports metadata. Tags with the form key=value will be split and used as a Map key and value respectively. Tags without the equal = sign, will be used as both the key and value. + +application.yml + +spring: + cloud: + consul: + discovery: + tags: foo=bar, baz + + +The above configuration will result in a map with foo→bar and baz→baz. +
+
+Making the Consul Instance ID Unique +By default a consul instance is registered with an ID that is equal to its Spring Application Context ID. By default, the Spring Application Context ID is ${spring.application.name}:comma,separated,profiles:${server.port}. For most cases, this will allow multiple instances of one service to run on one machine. If further uniqueness is required, Using Spring Cloud you can override this by providing a unique identifier in spring.cloud.consul.discovery.instanceId. For example: + +application.yml + +spring: + cloud: + consul: + discovery: + instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}} + + +With this metadata, and multiple service instances deployed on localhost, the random value will kick in there to make the instance unique. In Cloudfoundry the vcap.application.instance_id will be populated automatically in a Spring Boot application, so the random value will not be needed. +
+
+
+Looking up services +
+Using Ribbon +Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate +for looking up services using the logical service names/ids instead of physical URLs. Both Feign and the discovery-aware RestTemplate utilize Ribbon for client-side load balancing. +If you want to access service STORES using the RestTemplate simply declare: +@LoadBalanced +@Bean +public RestTemplate loadbalancedRestTemplate() { + new RestTemplate(); +} +and use it like this (notice how we use the STORES service name/id from Consul instead of a fully qualified domainname): +@Autowired +RestTemplate restTemplate; + +public String getFirstProduct() { + return this.restTemplate.getForObject("https://STORES/products/1", String.class); +} +If you have Consul clusters in multiple datacenters and you want to access a service in another datacenter a service name/id alone is not enough. In that case +you use property spring.cloud.consul.discovery.datacenters.STORES=dc-west where STORES is the service name/id and dc-west is the datacenter +where the STORES service lives. +
+
+Using the DiscoveryClient +You can also use the org.springframework.cloud.client.discovery.DiscoveryClient which provides a simple API for discovery clients that is not specific to Netflix, e.g. +@Autowired +private DiscoveryClient discoveryClient; + +public String serviceUrl() { + List<ServiceInstance> list = discoveryClient.getInstances("STORES"); + if (list != null && list.size() > 0 ) { + return list.get(0).getUri(); + } + return null; +} +
+
+ + +Distributed Configuration with Consul +Consul provides a Key/Value Store for storing configuration and other metadata. Spring Cloud Consul Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config folder by default. Multiple PropertySource instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created: +config/testApp,dev/ +config/testApp/ +config/application,dev/ +config/application/ +The most specific property source is at the top, with the least specific at the bottom. Properties in the config/application folder are applicable to all applications using consul for configuration. Properties in the config/testApp folder are only available to the instances of the service named "testApp". +Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh will cause the configuration to be reloaded. will also automatically detect changes and reload the application context. +
+How to activate +To get started with Consul Configuration use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-config. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train. +This will enable auto-configuration that will setup Spring Cloud Consul Config. +
+
+Customizing +Consul Config may be customized using the following properties: + +bootstrap.yml + +spring: + cloud: + consul: + config: + enabled: true + prefix: configuration + defaultContext: apps + profileSeparator: '::' + + + + +enabled setting this value to "false" disables Consul Config + + +prefix sets the base folder for configuration values + + +defaultContext sets the folder name used by all applications + + +profileSeparator sets the value of the separator used to separate the profile name in property sources with profiles + + +
+
+Config Watch +The Consul Config Watch takes advantage of the ability of consul to watch a key prefix. The Config Watch makes a blocking Consul HTTP API call to determine if any relevant configuration data has changed for the current application. If there is new configuration data a Refresh Event is published. This is equivalent to calling the /refresh actuator endpoint. +To change the frequency of when the Config Watch is called change spring.cloud.consul.config.watch.delay. The default value is 1000, which is in milliseconds. +To disable the Config Watch set spring.cloud.consul.config.watch.enabled=false. +
+
+YAML or Properties with Config +It may be more convenient to store a blob of properties in YAML or Properties format as opposed to individual key/value pairs. Set the spring.cloud.consul.config.format property to YAML or PROPERTIES. For example to use YAML: + +bootstrap.yml + +spring: + cloud: + consul: + config: + format: YAML + + +YAML must be set in the appropriate data key in consul. Using the defaults above the keys would look like: +config/testApp,dev/data +config/testApp/data +config/application,dev/data +config/application/data +You could store a YAML document in any of the keys listed above. +You can change the data key using spring.cloud.consul.config.data-key. +
+
+git2consul with Config +git2consul is a Consul community project that loads files from a git repository to individual keys into Consul. By default the names of the keys are names of the files. YAML and Properties files are supported with file extensions of .yml and .properties respectively. Set the spring.cloud.consul.config.format property to FILES. For example: + +bootstrap.yml + +spring: + cloud: + consul: + config: + format: FILES + + +Given the following keys in /config, the development profile and an application name of foo: +.gitignore +application.yml +bar.properties +foo-development.properties +foo-production.yml +foo.properties +master.ref +the following property sources would be created: +config/foo-development.properties +config/foo.properties +config/application.yml +The value of each key needs to be a properly formatted YAML or Properties file. +
+
+Fail Fast +It may be convenient in certain circumstances (like local development or certain test scenarios) to not fail if consul isn’t available for configuration. Setting spring.cloud.consul.config.failFast=false in bootstrap.yml will cause the configuration module to log a warning rather than throw an exception. This will allow the application to continue startup normally. +
+ + +Consul Retry +If you expect that the consul agent may occasionally be unavailable when +your app starts, you can ask it to keep trying after a failure. You need to add +spring-retry and spring-boot-starter-aop to your classpath. The default +behaviour is to retry 6 times with an initial backoff interval of 1000ms and an +exponential multiplier of 1.1 for subsequent backoffs. You can configure these +properties (and others) using spring.cloud.consul.retry.* configuration properties. +This works with both Spring Cloud Consul Config and Discovery registration. + +To take full control of the retry add a @Bean of type +RetryOperationsInterceptor with id "consulRetryInterceptor". Spring +Retry has a RetryInterceptorBuilder that makes it easy to create one. + + + +Spring Cloud Bus with Consul +
+How to activate +To get started with the Consul Bus use the starter with group org.springframework.cloud and artifact id spring-cloud-starter-consul-bus. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train. +See the Spring Cloud Bus documentation for the available actuator endpoints and howto send custom messages. +
+ + +Circuit Breaker with Hystrix +Applications can use the Hystrix Circuit Breaker provided by the Spring Cloud Netflix project by including this starter in the projects pom.xml: spring-cloud-starter-hystrix. Hystrix doesn’t depend on the Netflix Discovery Client. The @EnableHystrix annotation should be placed on a configuration class (usually the main class). Then methods can be annotated with @HystrixCommand to be protected by a circuit breaker. See the documentation for more details. + + +Hystrix metrics aggregation with Turbine and Consul +Turbine (provided by the Spring Cloud Netflix project), aggregates multiple instances Hystrix metrics streams, so the dashboard can display an aggregate view. Turbine uses the DiscoveryClient interface to lookup relevant instances. To use Turbine with Spring Cloud Consul, configure the Turbine application in a manner similar to the following examples: + +pom.xml + +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-netflix-turbine</artifactId> +</dependency> +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-consul-discovery</artifactId> +</dependency> + + +Notice that the Turbine dependency is not a starter. The turbine starter includes support for Netflix Eureka. + +application.yml + +spring.application.name: turbine +applications: consulhystrixclient +turbine: + aggregator: + clusterConfig: ${applications} + appConfig: ${applications} + + +The clusterConfig and appConfig sections must match, so it’s useful to put the comma-separated list of service ID’s into a separate configuration property. + +Turbine.java + +@EnableTurbine +@SpringBootApplication +public class Turbine { + public static void main(String[] args) { + SpringApplication.run(DemoturbinecommonsApplication.class, args); + } +} + + + + + +Spring Cloud Zookeeper + +This project provides Zookeeper integrations for Spring Boot apps through autoconfiguration +and binding to the Spring Environment and other Spring programming model idioms. With a few +simple annotations you can quickly enable and configure the common patterns inside your +application and build large distributed systems with Zookeeper based components. The +patterns provided include Service Discovery and Configuration. +Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker +(Hystrix) are provided by integration with Spring Cloud Netflix. + + +Install Zookeeper +Please see the installation documentation for instructions on how to install Zookeeper. + + +Service Discovery with Zookeeper +Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Curator(A java library for Zookeeper) provides Service Discovery services via Service Discovery Extension. Spring Cloud Zookeeper leverages this extension for service registration and discovery. +
+How to activate +Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery will enable auto-configuration that will setup Spring Cloud Zookeeper Discovery. + +You still need to include org.springframework.boot:spring-boot-starter-web for web functionality. + +
+
+Registering with Zookeeper +When a client registers with Zookeeper, it provides meta-data about itself such as host and port, id and name. +Example Zookeeper client: +@SpringBootApplication +@RestController +public class Application { + + @RequestMapping("/") + public String home() { + return "Hello world"; + } + + public static void main(String[] args) { + new SpringApplicationBuilder(Application.class).web(true).run(args); + } + +} +(i.e. utterly normal Spring Boot app). If Zookeeper is located somewhere other than localhost:2181, the configuration is required to locate the server. Example: + +application.yml + +spring: + cloud: + zookeeper: + connect-string: localhost:2181 + + + +If you use Spring Cloud Zookeeper Config, the above values will need to be placed in bootstrap.yml instead of application.yml. + +The default service name, instance id and port, taken from the Environment, are ${spring.application.name}, the Spring Context ID and ${server.port} respectively. +Having spring-cloud-starter-zookeeper-discovery on the classpath makes the app into both a Zookeeper "service" (i.e. it registers itself) and a "client" (i.e. it can query Zookeeper to locate other services). +If you would like to disable the Zookeeper Discovery Client you can set spring.cloud.zookeeper.discovery.enabled to false. +
+
+Using the DiscoveryClient +Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate using the logical service names instead of physical URLs. +You can also use the org.springframework.cloud.client.discovery.DiscoveryClient which provides a simple API for discovery clients that is not specific to Netflix, e.g. +@Autowired +private DiscoveryClient discoveryClient; + +public String serviceUrl() { + List<ServiceInstance> list = discoveryClient.getInstances("STORES"); + if (list != null && list.size() > 0 ) { + return list.get(0).getUri().toString(); + } + return null; +} +
+ + +Using Spring Cloud Zookeeper with Spring Cloud Netflix Components +Spring Cloud Netflix supplies useful tools that work regardless of which DiscoveryClient implementation is used. Feign, Turbine, Ribbon and Zuul all work with Spring Cloud Zookeeper. +
+Ribbon with Zookeeper +Spring Cloud Zookeeper provides an implementation of Ribbon’s ServerList. When the spring-cloud-starter-zookeeper-discovery is used, Ribbon is auto-configured to use the ZookeeperServerList by default. +
+ + +Spring Cloud Zookeeper and Service Registry +Spring Cloud Zookeeper implements the ServiceRegistry interface allowing developers to register arbitrary service in a programmatic way. +The ServiceInstanceRegistration class offers a builder() method to create a Registration object that can be used by the ServiceRegistry. +@Autowired +private ZookeeperServiceRegistry serviceRegistry; + +public void registerThings() { + ZookeeperRegistration registration = ServiceInstanceRegistration.builder() + .defaultUriSpec() + .address("anyUrl") + .port(10) + .name("/a/b/c/d/anotherservice") + .build(); + this.serviceRegistry.register(registration); +} +
+Instance Status +Netflix Eureka supports having instances registered with the server that are OUT_OF_SERVICE and not returned as active service instances. This is very useful for behaviors such as blue/green deployments. The Curator Service Discovery recipe does not support this behavior. Taking advantage of the flexible payload has let Spring Cloud Zookeeper implement OUT_OF_SERVICE by updating some specific metadata and then filtering on that metadata in the Ribbon ZookeeperServerList. The ZookeeperServerList filters out all non-null instance statuses that do not equal UP. If the instance status field is empty, it is considered UP for backwards compatibility. To change the status of an instance POST OUT_OF_SERVICE to the ServiceRegistry instance status actuator endpoint. +---- +$ echo -n OUT_OF_SERVICE | http POST http://localhost:8081/service-registry/instance-status +---- +NOTE: The above example uses the `http` command from https://httpie.org +
+ + +Zookeeper Dependencies +
+Using the Zookeeper Dependencies +Spring Cloud Zookeeper gives you a possibility to provide dependencies of your application as properties. As dependencies you can understand other applications that are registered +in Zookeeper and which you would like to call via Feign (a REST client builder) +and also Spring RestTemplate. +You can also benefit from the Zookeeper Dependency Watchers functionality that lets you control and monitor what is the state of your dependencies and decide what to do with that. +
+
+How to activate Zookeeper Dependencies + + +Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery will enable auto-configuration that will setup Spring Cloud Zookeeper Dependencies. + + +If you have to have the spring.cloud.zookeeper.dependencies section properly set up - check the subsequent section for more details then the feature is active + + +You can have the dependencies turned off even if you’ve provided the dependencies in your properties. Just set the property spring.cloud.zookeeper.dependency.enabled to false (defaults to true). + + +
+
+Setting up Zookeeper Dependencies +Let’s take a closer look at an example of dependencies representation: + +application.yml + +spring.application.name: yourServiceName +spring.cloud.zookeeper: + dependencies: + newsletter: + path: /path/where/newsletter/has/registered/in/zookeeper + loadBalancerType: ROUND_ROBIN + contentTypeTemplate: application/vnd.newsletter.$version+json + version: v1 + headers: + header1: + - value1 + header2: + - value2 + required: false + stubs: org.springframework:foo:stubs + mailing: + path: /path/where/mailing/has/registered/in/zookeeper + loadBalancerType: ROUND_ROBIN + contentTypeTemplate: application/vnd.mailing.$version+json + version: v1 + required: true + + +Let’s now go through each part of the dependency one by one. The root property name is spring.cloud.zookeeper.dependencies. +
+Aliases +Below the root property you have to represent each dependency has by an alias due to the constraints of Ribbon (the application id has to be placed in the URL +thus you can’t pass any complex path like /foo/bar/name). The alias will be the name that you will use instead of serviceId for DiscoveryClient, Feign or RestTemplate. +In the aforementioned examples the aliases are newsletter and mailing. Example of Feign usage with newsletter would be: +@FeignClient("newsletter") +public interface NewsletterService { + @RequestMapping(method = RequestMethod.GET, value = "/newsletter") + String getNewsletters(); +} +
+
+Path +Represented by path yaml property. +Path is the path under which the dependency is registered under Zookeeper. Like presented before Ribbon operates on URLs thus this path is not compliant with its requirement. +That is why Spring Cloud Zookeeper maps the alias to the proper path. +
+
+Load balancer type +Represented by loadBalancerType yaml property. +If you know what kind of load balancing strategy has to be applied when calling this particular dependency then you can provide it in the yaml file and it will be automatically applied. +You can choose one of the following load balancing strategies + + +STICKY - once chosen the instance will always be called + + +RANDOM - picks an instance randomly + + +ROUND_ROBIN - iterates over instances over and over again + + +
+
+Content-Type template and version +Represented by contentTypeTemplate and version yaml property. +If you version your api via the Content-Type header then you don’t want to add this header to each of your requests. Also if you want to call a new version of the API you don’t want to +roam around your code to bump up the API version. That’s why you can provide a contentTypeTemplate with a special $version placeholder. That placeholder will be filled by the value of the +version yaml property. Let’s take a look at an example. +Having the following contentTypeTemplate: +application/vnd.newsletter.$version+json +and the following version: +v1 +Will result in setting up of a Content-Type header for each request: +application/vnd.newsletter.v1+json +
+
+Default headers +Represented by headers map in yaml +Sometimes each call to a dependency requires setting up of some default headers. In order not to do that in code you can set them up in the yaml file. +Having the following headers section: +headers: + Accept: + - text/html + - application/xhtml+xml + Cache-Control: + - no-cache +Results in adding the Accept and Cache-Control headers with appropriate list of values in your HTTP request. +
+
+Obligatory dependencies +Represented by required property in yaml +If one of your dependencies is required to be up and running when your application is booting then it’s enough to set up the required: true property in the yaml file. +If your application can’t localize the required dependency during boot time it will throw an exception and the Spring Context will fail to set up. +In other words your application won’t be able to start if the required dependency is not registered in Zookeeper. +You can read more about Spring Cloud Zookeeper Presence Checker in the following sections. +
+
+Stubs +You can provide a colon separated path to the JAR containing stubs of the dependency. Example +stubs: org.springframework:foo:stubs +means that for a particular dependencies can be found under: + + +groupId: org.springframework + + +artifactId: foo + + +classifier: stubs - this is the default value + + +This is actually equal to +stubs: org.springframework:foo +since stubs is the default classifier. +
+
+
+Configuring Spring Cloud Zookeeper Dependencies +There is a bunch of properties that you can set to enable / disable parts of Zookeeper Dependencies functionalities. + + +spring.cloud.zookeeper.dependencies - if you don’t set this property you won’t benefit from Zookeeper Dependencies + + +spring.cloud.zookeeper.dependency.ribbon.enabled (enabled by default) - Ribbon requires explicit global configuration or a particular one for a dependency. By turning on this property +runtime load balancing strategy resolution is possible and you can profit from the loadBalancerType section of the Zookeeper Dependencies. The configuration that needs this property +has an implementation of LoadBalancerClient that delegates to the ILoadBalancer presented in the next bullet + + +spring.cloud.zookeeper.dependency.ribbon.loadbalancer (enabled by default) - thanks to this property the custom ILoadBalancer knows that the part of the URI passed to Ribbon might +actually be the alias that has to be resolved to a proper path in Zookeeper. Without this property you won’t be able to register applications under nested paths. + + +spring.cloud.zookeeper.dependency.headers.enabled (enabled by default) - this property registers such a RibbonClient that automatically will append appropriate headers and content +types with version as presented in the Dependency configuration. Without this setting of those two parameters will not be operational. + + +spring.cloud.zookeeper.dependency.resttemplate.enabled (enabled by default) - when enabled will modify the request headers of @LoadBalanced annotated RestTemplate so that it passes +headers and content type with version set in Dependency configuration. Wihtout this setting of those two parameters will not be operational. + + +
+ + +Spring Cloud Zookeeper Dependency Watcher +The Dependency Watcher mechanism allows you to register listeners to your dependencies. The functionality is in fact an implementation of the Observator pattern. When a dependency changes +its state (UP or DOWN) then some custom logic can be applied. +
+How to activate +Spring Cloud Zookeeper Dependencies functionality needs to be enabled to profit from Dependency Watcher mechanism. +
+
+Registering a listener +In order to register a listener you have to implement an interface org.springframework.cloud.zookeeper.discovery.watcher.DependencyWatcherListener and register it as a bean. +The interface gives you one method: + void stateChanged(String dependencyName, DependencyState newState); +If you want to register a listener for a particular dependency then the dependencyName would be the discriminator for your concrete implementation. newState will provide you with information + whether your dependency has changed to CONNECTED or DISCONNECTED. +
+
+Presence Checker +Bound with Dependency Watcher is the functionality called Presence Checker. It allows you to provide custom behaviour upon booting of your application to react accordingly to the state +of your dependencies. +The default implementation of the abstract org.springframework.cloud.zookeeper.discovery.watcher.presence.DependencyPresenceOnStartupVerifier class is the +org.springframework.cloud.zookeeper.discovery.watcher.presence.DefaultDependencyPresenceOnStartupVerifier which works in the following way. + + +If the dependency is marked us required and it’s not in Zookeeper then upon booting your application will throw an exception and shutdown + + +If dependency is not required the org.springframework.cloud.zookeeper.discovery.watcher.presence.LogMissingDependencyChecker will log that application is missing at WARN level + + +The functionality can be overriden since the DefaultDependencyPresenceOnStartupVerifier is registered only when there is no bean of DependencyPresenceOnStartupVerifier. +
+ + +Distributed Configuration with Zookeeper +Zookeeper provides a hierarchical namespace that allows clients to store arbitrary data, such as configuration data. Spring Cloud Zookeeper Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config namespace by default. Multiple PropertySource instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created: +config/testApp,dev +config/testApp +config/application,dev +config/application +The most specific property source is at the top, with the least specific at the bottom. Properties is the config/application namespace are applicable to all applications using zookeeper for configuration. Properties in the config/testApp namespace are only available to the instances of the service named "testApp". +Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh will cause the configuration to be reloaded. Watching the configuration namespace (which Zookeeper supports) is not currently implemented, but will be a future addition to this project. +
+How to activate +Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-config will enable auto-configuration that will setup Spring Cloud Zookeeper Config. +
+
+Customizing +Zookeeper Config may be customized using the following properties: + +bootstrap.yml + +spring: + cloud: + zookeeper: + config: + enabled: true + root: configuration + defaultContext: apps + profileSeparator: '::' + + + + +enabled setting this value to "false" disables Zookeeper Config + + +root sets the base namespace for configuration values + + +defaultContext sets the name used by all applications + + +profileSeparator sets the value of the separator used to separate the profile name in property sources with profiles + + +
+
+ACLs +You can add authentication information for Zookeeper ACLs by calling the addAuthInfo method of a +CuratorFramework bean. One way to accomplish this is by providing your own CuratorFramework bean: +@BoostrapConfiguration +public class CustomCuratorFrameworkConfig { + + @Bean + public CuratorFramework curatorFramework() { + CuratorFramework curator = new CuratorFramework(); + curator.addAuthInfo("digest", "user:password".getBytes()); + return curator; + } + +} +Consult the ZookeeperAutoConfiguration class +to see how the CuratorFramework bean is configured by default. +Alternatively, you can add your credentials from a class that depends on the existing +CuratorFramework bean: +@BoostrapConfiguration +public class DefaultCuratorFrameworkConfig { + + public ZookeeperConfig(CuratorFramework curator) { + curator.addAuthInfo("digest", "user:password".getBytes()); + } + +} +This must occur during the boostrapping phase. You can register configuration classes to run +during this phase by annotating them with @BootstrapConfiguration and including them in a +comma-separated list set as the value of the property +org.springframework.cloud.bootstrap.BootstrapConfiguration in the file +resources/META-INF/spring.factories: + +resources/META-INF/spring.factories + +org.springframework.cloud.bootstrap.BootstrapConfiguration=\ +my.project.CustomCuratorFrameworkConfig,\ +my.project.DefaultCuratorFrameworkConfig + + +
+ + + +Spring Boot Cloud CLI + +Spring Boot CLI provides Spring +Boot command line features for Spring +Cloud. You can write Groovy scripts to run Spring Cloud component +applications (e.g. @EnableEurekaServer). You can also easily do +things like encryption and decryption to support Spring Cloud Config +clients with secret configuration values. With the Launcher CLI you +can launch services like Eureka, Zipkin, Config Server +conveniently all at once from the command line (very useful at +development time). + +Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. + + + +Installation +To install, make +sure you have +Spring Boot CLI +(1.5.2 or better): +$ spring version +Spring CLI v1.5.4.RELEASE +E.g. for SDKMan users +$ sdk install springboot 1.5.4.RELEASE +$ sdk use springboot 1.5.4.RELEASE +and install the Spring Cloud plugin +$ mvn install +$ spring install org.springframework.cloud:spring-cloud-cli:1.4.0.BUILD-SNAPSHOT + +Prerequisites: to use the encryption and decryption features +you need the full-strength JCE installed in your JVM (it’s not there by default). +You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" +from Oracle, and follow instructions for installation (essentially replace the 2 policy files +in the JRE lib/security directory with the ones that you downloaded). + + + +Running Spring Cloud Services in Development +The Launcher CLI can be used to run common services like Eureka, +Config Server etc. from the command line. To list the available +services you can do spring cloud --list, and to launch a default set +of services just spring cloud. To choose the services to deploy, +just list them on the command line, e.g. +$ spring cloud eureka configserver h2 kafka stubrunner zipkin +Summary of supported deployables: + + + + + + + + +Service +Name +Address +Description + + + + +eureka +Eureka Server +http://localhost:8761 +Eureka server for service registration and discovery. All the other services show up in its catalog by default. + + +configserver +Config Server +http://localhost:8888 +Spring Cloud Config Server running in the "native" profile and serving configuration from the local directory ./launcher + + +h2 +H2 Database +http://localhost:9095 (console), jdbc:h2:tcp://localhost:9096/{data} +Relation database service. Use a file path for {data} (e.g. ./target/test) when you connect. Remember that you can add ;MODE=MYSQL or ;MODE=POSTGRESQL to connect with compatibility to other server types. + + +kafka +Kafka Broker +http://localhost:9091 (actuator endpoints), localhost:9092 + + + +hystrixdashboard +Hystrix Dashboard +http://localhost:7979 +Any Spring Cloud app that declares Hystrix circuit breakers publishes metrics on /hystrix.stream. Type that address into the dashboard to visualize all the metrics, + + +dataflow +Dataflow Server +http://localhost:9393 +Spring Cloud Dataflow server with UI at /admin-ui. Connect the Dataflow shell to target at root path. + + +zipkin +Zipkin Server +http://localhost:9411 +Zipkin Server with UI for visualizing traces. Stores span data in memory and accepts them via HTTP POST of JSON data. + + +stubrunner +Stub Runner Boot +http://localhost:8750 +Downloads WireMock stubs, starts WireMock and feeds the started servers with stored stubs. Pass stubrunner.ids to pass stub coordinates and then go to http://localhost:8750/stubs. + + + + +Each of these apps can be configured using a local YAML file with the same name (in the current +working directory or a subdirectory called "config" or in ~/.spring-cloud). E.g. in configserver.yml you might want to +do something like this to locate a local git repository for the backend: + +configserver.yml + +spring: + profiles: + active: git + cloud: + config: + server: + git: + uri: file://${user.home}/dev/demo/config-repo + + +E.g. in Stub Runner app you could fetch stubs from your local .m2 in the following way. + +stubrunner.yml + +stubrunner: + workOffline: true + ids: + - com.example:beer-api-producer:+:9876 + + +
+Adding Additional Applications +Additional applications can be added to ./config/cloud.yml (not +./config.yml because that would replace the defaults), e.g. with + +config/cloud.yml + +spring: + cloud: + launcher: + deployables: + source: + coordinates: maven://com.example:source:0.0.1-SNAPSHOT + port: 7000 + sink: + coordinates: maven://com.example:sink:0.0.1-SNAPSHOT + port: 7001 + + +when you list the apps: +$ spring cloud --list +source sink configserver dataflow eureka h2 hystrixdashboard kafka stubrunner zipkin +(notice the additional apps at the start of the list). +
+ + +Writing Groovy Scripts and Running Applications +Spring Cloud CLI has support for most of the Spring Cloud declarative +features, such as the @Enable* class of annotations. For example, +here is a fully functional Eureka server + +app.groovy + +@EnableEurekaServer +class Eureka {} + + +which you can run from the command line like this +$ spring run app.groovy +To include additional dependencies, often it suffices just to add the +appropriate feature-enabling annotation, e.g. @EnableConfigServer, +@EnableOAuth2Sso or @EnableEurekaClient. To manually include a +dependency you can use a @Grab with the special "Spring Boot" short +style artifact co-ordinates, i.e. with just the artifact ID (no need +for group or version information), e.g. to set up a client app to +listen on AMQP for management events from the Spring CLoud Bus: + +app.groovy + +@Grab('spring-cloud-starter-bus-amqp') +@RestController +class Service { + @RequestMapping('/') + def home() { [message: 'Hello'] } +} + + + + +Encryption and Decryption +The Spring Cloud CLI comes with an "encrypt" and a "decrypt" +command. Both accept arguments in the same form with a key specified +as a mandatory "--key", e.g. +$ spring encrypt mysecret --key foo +682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda +$ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda +mysecret +To use a key in a file (e.g. an RSA public key for encyption) prepend +the key value with "@" and provide the file path, e.g. +$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub +AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+... + + + +Spring Cloud Security + +Spring Cloud Security offers a set of primitives for building secure +applications and services with minimum fuss. A declarative model which +can be heavily configured externally (or centrally) lends itself to +the implementation of large systems of co-operating, remote components, +usually with a central indentity management service. It is also extremely +easy to use in a service platform like Cloud Foundry. Building on +Spring Boot and Spring Security OAuth2 we can quickly create systems that +implement common patterns like single sign on, token relay and token +exchange. + +Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. + + + +Quickstart +
+OAuth2 Single Sign On +Here’s a Spring Cloud "Hello World" app with HTTP Basic +authentication and a single user account: + +app.groovy + +@Grab('spring-boot-starter-security') +@Controller +class Application { + + @RequestMapping('/') + String home() { + 'Hello World' + } + +} + + +You can run it with spring run app.groovy and watch the logs for the password (username is "user"). So far this is just the default for a Spring Boot app. +Here’s a Spring Cloud app with OAuth2 SSO: + +app.groovy + +@Controller +@EnableOAuth2Sso +class Application { + + @RequestMapping('/') + String home() { + 'Hello World' + } + +} + + +Spot the difference? This app will actually behave exactly the same as +the previous one, because it doesn’t know it’s OAuth2 credentals +yet. +You can register an app in github quite easily, so try that if you +want a production app on your own domain. If you are happy to test on +localhost:8080, then set up these properties in your application +configuration: + +application.yml + +security: + oauth2: + client: + clientId: bd1c0a783ccdd1c9b9e4 + clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1 + accessTokenUri: https://github.com/login/oauth/access_token + userAuthorizationUri: https://github.com/login/oauth/authorize + clientAuthenticationScheme: form + resource: + userInfoUri: https://api.github.com/user + preferTokenInfo: false + + +run the app above and it will redirect to github for authorization. If +you are already signed into github you won’t even notice that it has +authenticated. These credentials will only work if your app is +running on port 8080. +To limit the scope that the client asks for when it obtains an access token +you can set security.oauth2.client.scope (comma separated or an array in YAML). By +default the scope is empty and it is up to to Authorization Server to +decide what the defaults should be, usually depending on the settings in +the client registration that it holds. + +The examples above are all Groovy scripts. If you want to write the +same code in Java (or Groovy) you need to add Spring Security OAuth2 +to the classpath (e.g. see the +sample here). + +
+
+OAuth2 Protected Resource +You want to protect an API resource with an OAuth2 token? Here’s a +simple example (paired with the client above): + +app.groovy + +@Grab('spring-cloud-starter-security') +@RestController +@EnableResourceServer +class Application { + + @RequestMapping('/') + def home() { + [message: 'Hello World'] + } + +} + + +and + +application.yml + +security: + oauth2: + resource: + userInfoUri: https://api.github.com/user + preferTokenInfo: false + + +
+ + +More Detail +
+Single Sign On + +All of the OAuth2 SSO and resource server features moved to Spring Boot +in version 1.3. You can find documentation in the +Spring Boot user guide. + +
+
+Token Relay +A Token Relay is where an OAuth2 consumer acts as a Client and +forwards the incoming token to outgoing resource requests. The +consumer can be a pure Client (like an SSO application) or a Resource +Server. +
+Client Token Relay +If your app is a user facing OAuth2 client (i.e. has declared +@EnableOAuth2Sso or @EnableOAuth2Client) then it has an +OAuth2ClientContext in request scope from Spring Boot. You can +create your own OAuth2RestTemplate from this context and an +autowired OAuth2ProtectedResourceDetails, and then the context will +always forward the access token downstream, also refreshing the access +token automatically if it expires. (These are features of Spring +Security and Spring Boot.) + +Spring Boot (1.4.1) does not create an +OAuth2ProtectedResourceDetails automatically if you are using +client_credentials tokens. In that case you need to create your own +ClientCredentialsResourceDetails and configure it with +@ConfigurationProperties("security.oauth2.client"). + +
+
+Client Token Relay in Zuul Proxy +If your app also has a +Spring +Cloud Zuul embedded reverse proxy (using @EnableZuulProxy) then you +can ask it to forward OAuth2 access tokens downstream to the services +it is proxying. Thus the SSO app above can be enhanced simply like +this: + +app.groovy + +@Controller +@EnableOAuth2Sso +@EnableZuulProxy +class Application { + +} + + +and it will (in addition to logging the user in and grabbing a token) +pass the authentication token downstream to the /proxy/* +services. If those services are implemented with +@EnableResourceServer then they will get a valid token in the +correct header. +How does it work? The @EnableOAuth2Sso annotation pulls in +spring-cloud-starter-security (which you could do manually in a +traditional app), and that in turn triggers some autoconfiguration for +a ZuulFilter, which itself is activated because Zuul is on the +classpath (via @EnableZuulProxy). The +filter +just extracts an access token from the currently authenticated user, +and puts it in a request header for the downstream requests. +
+
+Resource Server Token Relay +If your app has @EnableResourceServer you might want to relay the +incoming token downstream to other services. If you use a +RestTemplate to contact the downstream services then this is just a +matter of how to create the template with the right context. +If your service uses UserInfoTokenServices to authenticate incoming +tokens (i.e. it is using the security.oauth2.user-info-uri +configuration), then you can simply create an OAuth2RestTemplate +using an autowired OAuth2ClientContext (it will be populated by the +authentication process before it hits the backend code). Equivalently +(with Spring Boot 1.4), you could inject a +UserInfoRestTemplateFactory and grab its OAuth2RestTemplate in +your configuration. For example: + +MyConfiguration.java + +@Bean +public OAuth2RestTemplate restTemplate(UserInfoRestTemplateFactory factory) { + return factory.getUserInfoRestTemplate(); +} + + +This rest template will then have the same OAuth2ClientContext +(request-scoped) that is used by the authentication filter, so you can +use it to send requests with the same access token. +If your app is not using UserInfoTokenServices but is still a client +(i.e. it declares @EnableOAuth2Client or @EnableOAuth2Sso), then +with Spring Security Cloud any OAuth2RestOperations that the user +creates from an @Autowired @OAuth2Context will also forward +tokens. This feature is implemented by default as an MVC handler +interceptor, so it only works in Spring MVC. If you are not using MVC +you could use a custom filter or AOP interceptor wrapping an +AccessTokenContextRelay to provide the same feature. +Here’s a basic +example showing the use of an autowired rest template created +elsewhere ("foo.com" is a Resource Server accepting the same tokens as +the surrounding app): + +MyController.java + +@Autowired +private OAuth2RestOperations restTemplate; + +@RequestMapping("/relay") +public String relay() { + ResponseEntity<String> response = + restTemplate.getForEntity("https://foo.com/bar", String.class); + return "Success! (" + response.getBody() + ")"; +} + + +If you don’t want to forward tokens (and that is a valid +choice, since you might want to act as yourself, rather than the +client that sent you the token), then you only need to create your own +OAuth2Context instead of autowiring the default one. +Feign clients will also pick up an interceptor that uses the +OAuth2ClientContext if it is available, so they should also do a +token relay anywhere where a RestTemplate would. +
+
+ + +Configuring Authentication Downstream of a Zuul Proxy +You can control the authorization behaviour downstream of an +@EnableZuulProxy through the proxy.auth.* settings. Example: + +application.yml + +proxy: + auth: + routes: + customers: oauth2 + stores: passthru + recommendations: none + + +In this example the "customers" service gets an OAuth2 token relay, +the "stores" service gets a passthrough (the authorization header is +just passed downstream), and the "recommendations" service has its +authorization header removed. The default behaviour is to do a token +relay if there is a token available, and passthru otherwise. +See + +ProxyAuthenticationProperties for full details. + + + +Spring Cloud for Cloud Foundry + +Spring Cloud for Cloudfoundry makes it easy to run +Spring Cloud apps in +Cloud Foundry (the Platform as a +Service). Cloud Foundry has the notion of a "service", which is +middlware that you "bind" to an app, essentially providing it with an +environment variable containing credentials (e.g. the location and +username to use for the service). +The spring-cloud-cloudfoundry-web project provides basic support for +some enhanced features of webapps in Cloud Foundry: binding +automatically to single-sign-on services and optionally enabling +sticky routing for discovery. +The spring-cloud-cloudfoundry-discovery project provides an +implementation of Spring Cloud Commons DiscoveryClient so you can +@EnableDiscoveryClient and provide your credentials as +spring.cloud.cloudfoundry.discovery.[email,password] and then you +can use the DiscoveryClient directly or via a LoadBalancerClient +(also *.url if you are not connecting to +Pivotal Web Services). +The first time you use it the discovery client might be slow owing to +the fact that it has to get an access token from Cloud Foundry. + + +Discovery +Here’s a Spring Cloud app with Cloud Foundry discovery: + +app.groovy + +@Grab('org.springframework.cloud:spring-cloud-cloudfoundry') +@RestController +@EnableDiscoveryClient +class Application { + + @Autowired + DiscoveryClient client + + @RequestMapping('/') + String home() { + 'Hello from ' + client.getLocalServiceInstance() + } + +} + + +If you run it without any service bindings: +$ spring jar app.jar app.groovy +$ cf push -p app.jar +It will show its app name in the home page. +The DiscoveryClient can lists all the apps in a space, according to +the credentials it is authenticated with, where the space defaults to +the one the client is running in (if any). If neither org nor space +are configured, they default per the user’s profile in Cloud Foundry. + + +Single Sign On + +All of the OAuth2 SSO and resource server features moved to Spring Boot +in version 1.3. You can find documentation in the +Spring Boot user guide. + +This project provides automatic binding from CloudFoundry service +credentials to the Spring Boot features. If you have a CloudFoundry +service called "sso", for instance, with credentials containing +"client_id", "client_secret" and "auth_domain", it will bind +automatically to the Spring OAuth2 client that you enable with +@EnableOAuth2Sso (from Spring Boot). The name of the service can be +parameterized using spring.oauth2.sso.serviceId. + + + +Spring Cloud Contract + +_Documentation Authors: Adam Dudczak, Mathias Düsterhöft, Marcin Grzejszczak, Dennis Kieselhorst, Jakub Kubryński, Karol Lassak, +Olga Maciaszek-Sharma, Mariusz Smykuła, Dave Syer, Jay Bryant +1.3.8.RELEASE + + +Spring Cloud Contract +You need confidence when pushing new features to a new application or service in a +distributed system. This project provides support for Consumer Driven Contracts and +service schemas in Spring applications (for both HTTP and message-based interactions), +covering a range of options for writing tests, publishing them as assets, and asserting +that a contract is kept by producers and consumers. + + +Spring Cloud Contract Verifier Introduction + +The Accurest project was initially started by Marcin Grzejszczak and Jakub Kubrynski +(Codearte) + +Spring Cloud Contract Verifier enables Consumer Driven Contract (CDC) development of +JVM-based applications. It moves TDD to the level of software architecture. +Spring Cloud Contract Verifier ships with Contract Definition Language (CDL). Contract +definitions are used to produce the following resources: + + +JSON stub definitions to be used by WireMock when doing integration testing on the +client code (client tests). Test code must still be written by hand, and test data is +produced by Spring Cloud Contract Verifier. + + +Messaging routes, if you’re using a messaging service. We integrate with Spring +Integration, Spring Cloud Stream, Spring AMQP, and Apache Camel. You can also set your +own integrations. + + +Acceptance tests (in JUnit or Spock) are used to verify if server-side implementation +of the API is compliant with the contract (server tests). A full test is generated by +Spring Cloud Contract Verifier. + + +
+Why a Contract Verifier? +Assume that we have a system consisting of multiple microservices: + + + + + +Microservices Architecture + + +
+Testing issues +If we wanted to test the application in top left corner to determine whether it can +communicate with other services, we could do one of two things: + + +Deploy all microservices and perform end-to-end tests. + + +Mock other microservices in unit/integration tests. + + +Both have their advantages but also a lot of disadvantages. +Deploy all microservices and perform end to end tests +Advantages: + + +Simulates production. + + +Tests real communication between services. + + +Disadvantages: + + +To test one microservice, we have to deploy 6 microservices, a couple of databases, +etc. + + +The environment where the tests run is locked for a single suite of tests (nobody else +would be able to run the tests in the meantime). + + +They take a long time to run. + + +The feedback comes very late in the process. + + +They are extremely hard to debug. + + +Mock other microservices in unit/integration tests +Advantages: + + +They provide very fast feedback. + + +They have no infrastructure requirements. + + +Disadvantages: + + +The implementor of the service creates stubs that might have nothing to do with +reality. + + +You can go to production with passing tests and failing production. + + +To solve the aforementioned issues, Spring Cloud Contract Verifier with Stub Runner was +created. The main idea is to give you very fast feedback, without the need to set up the +whole world of microservices. If you work on stubs, then the only applications you need +are those that your application directly uses. + + + + + +Stubbed Services + + +Spring Cloud Contract Verifier gives you the certainty that the stubs that you use were +created by the service that you’re calling. Also, if you can use them, it means that they +were tested against the producer’s side. In short, you can trust those stubs. +
+
+
+Purposes +The main purposes of Spring Cloud Contract Verifier with Stub Runner are: + + +To ensure that WireMock/Messaging stubs (used when developing the client) do exactly +what the actual server-side implementation does. + + +To promote ATDD method and Microservices architectural style. + + +To provide a way to publish changes in contracts that are immediately visible on both +sides. + + +To generate boilerplate test code to be used on the server side. + + + +Spring Cloud Contract Verifier’s purpose is NOT to start writing business +features in the contracts. Assume that we have a business use case of fraud check. If a +user can be a fraud for 100 different reasons, we would assume that you would create 2 +contracts, one for the positive case and one for the negative case. Contract tests are +used to test contracts between applications and not to simulate full behavior. + +
+
+How It Works +This section explores how Spring Cloud Contract Verifier with Stub Runner works. +
+Defining the contract +As consumers of services, we need to define what exactly we want to achieve. We need to +formulate our expectations. That is why we write contracts. +Assume that you want to send a request containing the ID of a client company and the +amount it wants to borrow from us. You also want to send it to the /fraudcheck url via +the PUT method. + +Groovy DSL + +package contracts + +org.springframework.cloud.contract.spec.Contract.make { + request { // (1) + method 'PUT' // (2) + url '/fraudcheck' // (3) + body([ // (4) + "client.id": $(regex('[0-9]{10}')), + loanAmount: 99999 + ]) + headers { // (5) + contentType('application/json') + } + } + response { // (6) + status 200 // (7) + body([ // (8) + fraudCheckStatus: "FRAUD", + "rejection.reason": "Amount too high" + ]) + headers { // (9) + contentType('application/json') + } + } +} + +/* +From the Consumer perspective, when shooting a request in the integration test: + +(1) - If the consumer sends a request +(2) - With the "PUT" method +(3) - to the URL "/fraudcheck" +(4) - with the JSON body that + * has a field `client.id` that matches a regular expression `[0-9]{10}` + * has a field `loanAmount` that is equal to `99999` +(5) - with header `Content-Type` equal to `application/json` +(6) - then the response will be sent with +(7) - status equal `200` +(8) - and JSON body equal to + { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +(9) - with header `Content-Type` equal to `application/json` + +From the Producer perspective, in the autogenerated producer-side test: + +(1) - A request will be sent to the producer +(2) - With the "PUT" method +(3) - to the URL "/fraudcheck" +(4) - with the JSON body that + * has a field `client.id` that will have a generated value that matches a regular expression `[0-9]{10}` + * has a field `loanAmount` that is equal to `99999` +(5) - with header `Content-Type` equal to `application/json` +(6) - then the test will assert if the response has been sent with +(7) - status equal `200` +(8) - and JSON body equal to + { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +(9) - with header `Content-Type` matching `application/json.*` + */ + + + +YAML + +request: # (1) + method: PUT # (2) + url: /fraudcheck # (3) + body: # (4) + "client.id": 1234567890 + loanAmount: 99999 + headers: # (5) + Content-Type: application/json + matchers: + body: + - path: $.['client.id'] # (6) + type: by_regex + value: "[0-9]{10}" +response: # (7) + status: 200 # (8) + body: # (9) + fraudCheckStatus: "FRAUD" + "rejection.reason": "Amount too high" + headers: # (10) + Content-Type: application/json;charset=UTF-8 + + +#From the Consumer perspective, when shooting a request in the integration test: +# +#(1) - If the consumer sends a request +#(2) - With the "PUT" method +#(3) - to the URL "/fraudcheck" +#(4) - with the JSON body that +# * has a field `client.id` +# * has a field `loanAmount` that is equal to `99999` +#(5) - with header `Content-Type` equal to `application/json` +#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}` +#(7) - then the response will be sent with +#(8) - status equal `200` +#(9) - and JSON body equal to +# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +#(10) - with header `Content-Type` equal to `application/json` +# +#From the Producer perspective, in the autogenerated producer-side test: +# +#(1) - A request will be sent to the producer +#(2) - With the "PUT" method +#(3) - to the URL "/fraudcheck" +#(4) - with the JSON body that +# * has a field `client.id` `1234567890` +# * has a field `loanAmount` that is equal to `99999` +#(5) - with header `Content-Type` equal to `application/json` +#(7) - then the test will assert if the response has been sent with +#(8) - status equal `200` +#(9) - and JSON body equal to +# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8` + + +
+
+Client Side +Spring Cloud Contract generates stubs, which you can use during client-side testing. +You get a running WireMock instance/Messaging route that simulates the service. +You would like to feed that instance with a proper stub definition. +At some point in time, you need to send a request to the Fraud Detection service. +ResponseEntity<FraudServiceResponse> response = + restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT, + new HttpEntity<>(request, httpHeaders), + FraudServiceResponse.class); +Annotate your test class with @AutoConfigureStubRunner. In the annotation provide the group id and artifact id for the Stub Runner to download stubs of your collaborators. +@RunWith(SpringRunner.class) +@SpringBootTest(webEnvironment=WebEnvironment.NONE) +@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true) +public class LoanApplicationServiceTests { +After that, during the tests, Spring Cloud Contract automatically finds the stubs +(simulating the real service) in the Maven repository and exposes them on a configured +(or random) port. +
+
+Server Side +Since you are developing your stub, you need to be sure that it actually resembles your +concrete implementation. You cannot have a situation where your stub acts in one way and +your application behaves in a different way, especially in production. +To ensure that your application behaves the way you define in your stub, tests are +generated from the stub you provide. +The autogenerated test looks, more or less, like this: +@Test +public void validate_shouldMarkClientAsFraud() throws Exception { + // given: + MockMvcRequestSpecification request = given() + .header("Content-Type", "application/vnd.fraud.v1+json") + .body("{\"client.id\":\"1234567890\",\"loanAmount\":99999}"); + + // when: + ResponseOptions response = given().spec(request) + .put("/fraudcheck"); + + // then: + assertThat(response.statusCode()).isEqualTo(200); + assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*"); + // and: + DocumentContext parsedJson = JsonPath.parse(response.getBody().asString()); + assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}"); + assertThatJson(parsedJson).field("['rejection.reason']").isEqualTo("Amount too high"); +} +
+
+
+Step-by-step Guide to Consumer Driven Contracts (CDC) +Consider an example of Fraud Detection and the Loan Issuance process. The business +scenario is such that we want to issue loans to people but do not want them to steal from +us. The current implementation of our system grants loans to everybody. +Assume that Loan Issuance is a client to the Fraud Detection server. In the current +sprint, we must develop a new feature: if a client wants to borrow too much money, then +we mark the client as a fraud. +Technical remark - Fraud Detection has an artifact-id of http-server, while Loan +Issuance has an artifact-id of http-client, and both have a group-id of com.example. +Social remark - both client and server development teams need to communicate directly and +discuss changes while going through the process. CDC is all about communication. +The server +side code is available here and the +client code here. + +In this case, the producer owns the contracts. Physically, all the contract are +in the producer’s repository. + +
+Technical note +If using the SNAPSHOT / Milestone / Release Candidate versions please add the +following section to your build: + +Maven + +<repositories> + <repository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </repository> + <repository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> + <repository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> +</repositories> +<pluginRepositories> + <pluginRepository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> +</pluginRepositories> + + + +Gradle + +repositories { + mavenCentral() + mavenLocal() + maven { url "https://repo.spring.io/snapshot" } + maven { url "https://repo.spring.io/milestone" } + maven { url "https://repo.spring.io/release" } +} + + +
+
+Consumer side (Loan Issuance) +As a developer of the Loan Issuance service (a consumer of the Fraud Detection server), you might do the following steps: + + +Start doing TDD by writing a test for your feature. + + +Write the missing implementation. + + +Clone the Fraud Detection service repository locally. + + +Define the contract locally in the repo of Fraud Detection service. + + +Add the Spring Cloud Contract Verifier plugin. + + +Run the integration tests. + + +File a pull request. + + +Create an initial implementation. + + +Take over the pull request. + + +Write the missing implementation. + + +Deploy your app. + + +Work online. + + +Start doing TDD by writing a test for your feature. +@Test +public void shouldBeRejectedDueToAbnormalLoanAmount() { + // given: + LoanApplication application = new LoanApplication(new Client("1234567890"), + 99999); + // when: + LoanApplicationResult loanApplication = service.loanApplication(application); + // then: + assertThat(loanApplication.getLoanApplicationStatus()) + .isEqualTo(LoanApplicationStatus.LOAN_APPLICATION_REJECTED); + assertThat(loanApplication.getRejectionReason()).isEqualTo("Amount too high"); +} +Assume that you have written a test of your new feature. If a loan application for a big +amount is received, the system should reject that loan application with some description. +Write the missing implementation. +At some point in time, you need to send a request to the Fraud Detection service. Assume +that you need to send the request containing the ID of the client and the amount the +client wants to borrow. You want to send it to the /fraudcheck url via the PUT method. +ResponseEntity<FraudServiceResponse> response = + restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT, + new HttpEntity<>(request, httpHeaders), + FraudServiceResponse.class); +For simplicity, the port of the Fraud Detection service is set to 8080, and the +application runs on 8090. +If you start the test at this point, it breaks, because no service currently runs on port +8080. +Clone the Fraud Detection service repository locally. +You can start by playing around with the server side contract. To do so, you must first +clone it. +$ git clone https://your-git-server.com/server-side.git local-http-server-repo +Define the contract locally in the repo of Fraud Detection service. +As a consumer, you need to define what exactly you want to achieve. You need to formulate +your expectations. To do so, write the following contract: + +Place the contract under src/test/resources/contracts/fraud folder. The fraud folder +is important because the producer’s test base class name references that folder. + + +Groovy DSL + +package contracts + +org.springframework.cloud.contract.spec.Contract.make { + request { // (1) + method 'PUT' // (2) + url '/fraudcheck' // (3) + body([ // (4) + "client.id": $(regex('[0-9]{10}')), + loanAmount: 99999 + ]) + headers { // (5) + contentType('application/json') + } + } + response { // (6) + status 200 // (7) + body([ // (8) + fraudCheckStatus: "FRAUD", + "rejection.reason": "Amount too high" + ]) + headers { // (9) + contentType('application/json') + } + } +} + +/* +From the Consumer perspective, when shooting a request in the integration test: + +(1) - If the consumer sends a request +(2) - With the "PUT" method +(3) - to the URL "/fraudcheck" +(4) - with the JSON body that + * has a field `client.id` that matches a regular expression `[0-9]{10}` + * has a field `loanAmount` that is equal to `99999` +(5) - with header `Content-Type` equal to `application/json` +(6) - then the response will be sent with +(7) - status equal `200` +(8) - and JSON body equal to + { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +(9) - with header `Content-Type` equal to `application/json` + +From the Producer perspective, in the autogenerated producer-side test: + +(1) - A request will be sent to the producer +(2) - With the "PUT" method +(3) - to the URL "/fraudcheck" +(4) - with the JSON body that + * has a field `client.id` that will have a generated value that matches a regular expression `[0-9]{10}` + * has a field `loanAmount` that is equal to `99999` +(5) - with header `Content-Type` equal to `application/json` +(6) - then the test will assert if the response has been sent with +(7) - status equal `200` +(8) - and JSON body equal to + { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +(9) - with header `Content-Type` matching `application/json.*` + */ + + + +YAML + +request: # (1) + method: PUT # (2) + url: /fraudcheck # (3) + body: # (4) + "client.id": 1234567890 + loanAmount: 99999 + headers: # (5) + Content-Type: application/json + matchers: + body: + - path: $.['client.id'] # (6) + type: by_regex + value: "[0-9]{10}" +response: # (7) + status: 200 # (8) + body: # (9) + fraudCheckStatus: "FRAUD" + "rejection.reason": "Amount too high" + headers: # (10) + Content-Type: application/json;charset=UTF-8 + + +#From the Consumer perspective, when shooting a request in the integration test: +# +#(1) - If the consumer sends a request +#(2) - With the "PUT" method +#(3) - to the URL "/fraudcheck" +#(4) - with the JSON body that +# * has a field `client.id` +# * has a field `loanAmount` that is equal to `99999` +#(5) - with header `Content-Type` equal to `application/json` +#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}` +#(7) - then the response will be sent with +#(8) - status equal `200` +#(9) - and JSON body equal to +# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +#(10) - with header `Content-Type` equal to `application/json` +# +#From the Producer perspective, in the autogenerated producer-side test: +# +#(1) - A request will be sent to the producer +#(2) - With the "PUT" method +#(3) - to the URL "/fraudcheck" +#(4) - with the JSON body that +# * has a field `client.id` `1234567890` +# * has a field `loanAmount` that is equal to `99999` +#(5) - with header `Content-Type` equal to `application/json` +#(7) - then the test will assert if the response has been sent with +#(8) - status equal `200` +#(9) - and JSON body equal to +# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" } +#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8` + + +The YML contract is quite straight-forward. However when you take a look at the Contract +written using a statically typed Groovy DSL - you might wonder what the +value(client(…​), server(…​)) parts are. By using this notation, Spring Cloud +Contract lets you define parts of a JSON block, a URL, etc., which are dynamic. In case +of an identifier or a timestamp, you need not hardcode a value. You want to allow some +different ranges of values. To enable ranges of values, you can set regular expressions +matching those values for the consumer side. You can provide the body by means of either +a map notation or String with interpolations. +Consult the docs +for more information. We highly recommend using the map notation! + +You must understand the map notation in order to set up contracts. Please read the +Groovy docs regarding JSON. + +The previously shown contract is an agreement between two sides that: + + +if an HTTP request is sent with all of + + +a PUT method on the /fraudcheck endpoint, + + +a JSON body with a client.id that matches the regular expression [0-9]{10} and +loanAmount equal to 99999, + + +and a Content-Type header with a value of application/vnd.fraud.v1+json, + + + + +then an HTTP response is sent to the consumer that + + +has status 200, + + +contains a JSON body with the fraudCheckStatus field containing a value FRAUD and +the rejectionReason field having value Amount too high, + + +and a Content-Type header with a value of application/vnd.fraud.v1+json. + + + + +Once you are ready to check the API in practice in the integration tests, you need to +install the stubs locally. +Add the Spring Cloud Contract Verifier plugin. +We can add either a Maven or a Gradle plugin. In this example, you see how to add Maven. +First, add the Spring Cloud Contract BOM. +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${spring-cloud-dependencies.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> +</dependencyManagement> +Next, add the Spring Cloud Contract Verifier Maven plugin +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <packageWithBaseClasses>com.example.fraud</packageWithBaseClasses> + </configuration> +</plugin> +Since the plugin was added, you get the Spring Cloud Contract Verifier features which, +from the provided contracts: + + +generate and run tests + + +produce and install stubs + + +You do not want to generate tests since you, as the consumer, want only to play with the +stubs. You need to skip the test generation and execution. When you execute: +$ cd local-http-server-repo +$ ./mvnw clean install -DskipTests +In the logs, you see something like this: +[INFO] --- spring-cloud-contract-maven-plugin:1.0.0.BUILD-SNAPSHOT:generateStubs (default-generateStubs) @ http-server --- +[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar +[INFO] +[INFO] --- maven-jar-plugin:2.6:jar (default-jar) @ http-server --- +[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar +[INFO] +[INFO] --- spring-boot-maven-plugin:1.5.5.BUILD-SNAPSHOT:repackage (default) @ http-server --- +[INFO] +[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ http-server --- +[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.jar +[INFO] Installing /some/path/http-server/pom.xml to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.pom +[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar +The following line is extremely important: +[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar +It confirms that the stubs of the http-server have been installed in the local +repository. +Run the integration tests. +In order to profit from the Spring Cloud Contract Stub Runner functionality of automatic +stub downloading, you must do the following in your consumer side project (Loan +Application service): +Add the Spring Cloud Contract BOM: +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${spring-cloud-dependencies.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> +</dependencyManagement> +Add the dependency to Spring Cloud Contract Stub Runner: +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-contract-stub-runner</artifactId> + <scope>test</scope> +</dependency> +Annotate your test class with @AutoConfigureStubRunner. In the annotation, provide the +group-id and artifact-id for the Stub Runner to download the stubs of your +collaborators. (Optional step) Because you’re playing with the collaborators offline, you +can also provide the offline work switch. +@RunWith(SpringRunner.class) +@SpringBootTest(webEnvironment=WebEnvironment.NONE) +@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true) +public class LoanApplicationServiceTests { +Now, when you run your tests, you see something like this: +2016-07-19 14:22:25.403 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Desired version is + - will try to resolve the latest version +2016-07-19 14:22:25.438 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolved version is 0.0.1-SNAPSHOT +2016-07-19 14:22:25.439 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolving artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT using remote repositories [] +2016-07-19 14:22:25.451 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolved artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar +2016-07-19 14:22:25.465 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Unpacking stub from JAR [URI: file:/path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar] +2016-07-19 14:22:25.475 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Unpacked file to [/var/folders/0p/xwq47sq106x1_g3dtv6qfm940000gq/T/contracts100276532569594265] +2016-07-19 14:22:27.737 INFO 41050 --- [ main] o.s.c.c.stubrunner.StubRunnerExecutor : All stubs are now running RunningStubs [namesAndPorts={com.example:http-server:0.0.1-SNAPSHOT:stubs=8080}] +This output means that Stub Runner has found your stubs and started a server for your app +with group id com.example, artifact id http-server with version 0.0.1-SNAPSHOT of +the stubs and with stubs classifier on port 8080. +File a pull request. +What you have done until now is an iterative process. You can play around with the +contract, install it locally, and work on the consumer side until the contract works as +you wish. +Once you are satisfied with the results and the test passes, publish a pull request to +the server side. Currently, the consumer side work is done. +
+
+Producer side (Fraud Detection server) +As a developer of the Fraud Detection server (a server to the Loan Issuance service): +Create an initial implementation. +As a reminder, you can see the initial implementation here: +@RequestMapping(value = "/fraudcheck", method = PUT) +public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) { +return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON); +} +Take over the pull request. +$ git checkout -b contract-change-pr master +$ git pull https://your-git-server.com/server-side-fork.git contract-change-pr +You must add the dependencies needed by the autogenerated tests: +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-contract-verifier</artifactId> + <scope>test</scope> +</dependency> +In the configuration of the Maven plugin, pass the packageWithBaseClasses property +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <packageWithBaseClasses>com.example.fraud</packageWithBaseClasses> + </configuration> +</plugin> + +This example uses "convention based" naming by setting the +packageWithBaseClasses property. Doing so means that the two last packages combine to +make the name of the base test class. In our case, the contracts were placed under +src/test/resources/contracts/fraud. Since you do not have two packages starting from +the contracts folder, pick only one, which should be fraud. Add the Base suffix and +capitalize fraud. That gives you the FraudBase test class name. + +All the generated tests extend that class. Over there, you can set up your Spring Context +or whatever is necessary. In this case, use Rest Assured MVC to +start the server side FraudDetectionController. +package com.example.fraud; + +import org.junit.Before; + +import io.restassured.module.mockmvc.RestAssuredMockMvc; + +public class FraudBase { + @Before + public void setup() { + RestAssuredMockMvc.standaloneSetup(new FraudDetectionController(), + new FraudStatsController(stubbedStatsProvider())); + } + + private StatsProvider stubbedStatsProvider() { + return fraudType -> { + switch (fraudType) { + case DRUNKS: + return 100; + case ALL: + return 200; + } + return 0; + }; + } + + public void assertThatRejectionReasonIsNull(Object rejectionReason) { + assert rejectionReason == null; + } +} +Now, if you run the ./mvnw clean install, you get something like this: +Results : + +Tests in error: + ContractVerifierTest.validate_shouldMarkClientAsFraud:32 » IllegalState Parsed... +This error occurs because you have a new contract from which a test was generated and it +failed since you have not implemented the feature. The auto-generated test would look +like this: +@Test +public void validate_shouldMarkClientAsFraud() throws Exception { + // given: + MockMvcRequestSpecification request = given() + .header("Content-Type", "application/vnd.fraud.v1+json") + .body("{\"client.id\":\"1234567890\",\"loanAmount\":99999}"); + + // when: + ResponseOptions response = given().spec(request) + .put("/fraudcheck"); + + // then: + assertThat(response.statusCode()).isEqualTo(200); + assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*"); + // and: + DocumentContext parsedJson = JsonPath.parse(response.getBody().asString()); + assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}"); + assertThatJson(parsedJson).field("['rejection.reason']").isEqualTo("Amount too high"); +} +If you used the Groovy DSL, you can see, all the producer() parts of the Contract that were present in the +value(consumer(…​), producer(…​)) blocks got injected into the test. +In case of using YAML, the same applied for the matchers sections of the response. +Note that, on the producer side, you are also doing TDD. The expectations are expressed +in the form of a test. This test sends a request to our own application with the URL, +headers, and body defined in the contract. It also is expecting precisely defined values +in the response. In other words, you have the red part of red, green, and +refactor. It is time to convert the red into the green. +Write the missing implementation. +Because you know the expected input and expected output, you can write the missing +implementation: +@RequestMapping(value = "/fraudcheck", method = PUT) +public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) { +if (amountGreaterThanThreshold(fraudCheck)) { + return new FraudCheckResult(FraudCheckStatus.FRAUD, AMOUNT_TOO_HIGH); +} +return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON); +} +When you execute ./mvnw clean install again, the tests pass. Since the Spring Cloud +Contract Verifier plugin adds the tests to the generated-test-sources, you can +actually run those tests from your IDE. +Deploy your app. +Once you finish your work, you can deploy your change. First, merge the branch: +$ git checkout master +$ git merge --no-ff contract-change-pr +$ git push origin master +Your CI might run something like ./mvnw clean deploy, which would publish both the +application and the stub artifacts. +
+
+Consumer Side (Loan Issuance) Final Step +As a developer of the Loan Issuance service (a consumer of the Fraud Detection server): +Merge branch to master. +$ git checkout master +$ git merge --no-ff contract-change-pr +Work online. +Now you can disable the offline work for Spring Cloud Contract Stub Runner and indicate +where the repository with your stubs is located. At this moment the stubs of the server +side are automatically downloaded from Nexus/Artifactory. You can switch off the value of +the workOffline parameter in your annotation. The following code shows an example of +achieving the same thing by changing the properties. +stubrunner: + ids: 'com.example:http-server-dsl:+:stubs:8080' + repositoryRoot: https://repo.spring.io/libs-snapshot +That’s it! +
+
+
+Dependencies +The best way to add dependencies is to use the proper starter dependency. +For stub-runner, use spring-cloud-starter-stub-runner. When you use a plugin, add +spring-cloud-starter-contract-verifier. +
+
+Additional Links +Here are some resources related to Spring Cloud Contract Verifier and Stub Runner. Note +that some may be outdated, because the Spring Cloud Contract Verifier project is under +constant development. +
+Spring Cloud Contract video +You can check out the video from the Warsaw JUG about Spring Cloud Contract: + +
+
+Readings + + +Slides from Marcin Grzejszczak’s talk about Accurest + + +Accurest related articles from Marcin Grzejszczak’s blog + + +Spring Cloud Contract related articles from Marcin Grzejszczak’s blog + + +Groovy docs regarding JSON + + +
+
+
+Samples +You can find some samples at +samples. +
+ + +Spring Cloud Contract FAQ +
+Why use Spring Cloud Contract Verifier and not X ? +For the time being Spring Cloud Contract Verifier is a JVM based tool. So it could be your first pick when you’re already creating +software for the JVM. This project has a lot of really interesting features but especially quite a few of them definitely make +Spring Cloud Contract Verifier stand out on the "market" of Consumer Driven Contract (CDC) tooling. Out of many the most interesting are: + + +Possibility to do CDC with messaging + + +Clear and easy to use, statically typed DSL + + +Possibility to copy paste your current JSON file to the contract and only edit its elements + + +Automatic generation of tests from the defined Contract + + +Stub Runner functionality - the stubs are automatically downloaded at runtime from Nexus / Artifactory + + +Spring Cloud integration - no discovery service is needed for integration tests + + +
+
+I don’t want to write a contract in Groovy! +No problem. You can write a contract in YAML! +
+
+What is this value(consumer(), producer()) ? +One of the biggest challenges related to stubs is their reusability. Only if they can be vastly used, will they serve their purpose. +What typically makes that difficult are the hard-coded values of request / response elements. For example dates or ids. +Imagine the following JSON request +{ + "time" : "2016-10-10 20:10:15", + "id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a", + "body" : "foo" +} +and JSON response +{ + "time" : "2016-10-10 21:10:15", + "id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051", + "body" : "bar" +} +Imagine the pain required to set proper value of the time field (let’s assume that this content is generated by the +database) by changing the clock in the system or providing stub implementations of data providers. The same is related +to the field called id. Will you create a stubbed implementation of UUID generator? Makes little sense…​ +So as a consumer you would like to send a request that matches any form of a time or any UUID. That way your system +will work as usual - will generate data and you won’t have to stub anything out. Let’s assume that in case of the aforementioned +JSON the most important part is the body field. You can focus on that and provide matching for other fields. In other words +you would like the stub to work like this: +{ + "time" : "SOMETHING THAT MATCHES TIME", + "id" : "SOMETHING THAT MATCHES UUID", + "body" : "foo" +} +As far as the response goes as a consumer you need a concrete value that you can operate on. So such a JSON is valid +{ + "time" : "2016-10-10 21:10:15", + "id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051", + "body" : "bar" +} +As you could see in the previous sections we generate tests from contracts. So from the producer’s side the situation looks +much different. We’re parsing the provided contract and in the test we want to send a real request to your endpoints. +So for the case of a producer for the request we can’t have any sort of matching. We need concrete values that the +producer’s backend can work on. Such a JSON would be a valid one: +{ + "time" : "2016-10-10 20:10:15", + "id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a", + "body" : "foo" +} +On the other hand from the point of view of the validity of the contract the response doesn’t necessarily have to +contain concrete values of time or id. Let’s say that you generate those on the producer side - again, you’d +have to do a lot of stubbing to ensure that you always return the same values. That’s why from the producer’s side +what you might want is the following response: +{ + "time" : "SOMETHING THAT MATCHES TIME", + "id" : "SOMETHING THAT MATCHES UUID", + "body" : "bar" +} +How can you then provide one time a matcher for the consumer and a concrete value for the producer and vice versa? +In Spring Cloud Contract we’re allowing you to provide a dynamic value. That means that it can differ for both +sides of the communication. You can pass the values: +Either via the value method +value(consumer(...), producer(...)) +value(stub(...), test(...)) +value(client(...), server(...)) +or using the $() method +$(consumer(...), producer(...)) +$(stub(...), test(...)) +$(client(...), server(...)) +You can read more about this in the Contract DSL section. +Calling value() or $() tells Spring Cloud Contract that you will be passing a dynamic value. +Inside the consumer() method you pass the value that should be used on the consumer side (in the generated stub). +Inside the producer() method you pass the value that should be used on the producer side (in the generated test). + +If on one side you have passed the regular expression and you haven’t passed the other, then the +other side will get auto-generated. + +Most often you will use that method together with the regex helper method. E.g. consumer(regex('[0-9]{10}')). +To sum it up the contract for the aforementioned scenario would look more or less like this (the regular expression +for time and UUID are simplified and most likely invalid but we want to keep things very simple in this example): +org.springframework.cloud.contract.spec.Contract.make { + request { + method 'GET' + url '/someUrl' + body([ + time : value(consumer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')), + id: value(consumer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}')) + body: "foo" + ]) + } + response { + status 200 + body([ + time : value(producer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')), + id: value([producer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}')) + body: "bar" + ]) + } +} + +Please read the Groovy docs related to JSON to understand how to +properly structure the request / response bodies. + +
+
+How to do Stubs versioning? +
+API Versioning +Let’s try to answer a question what versioning really means. If you’re referring to the API version then there are +different approaches. + + +use Hypermedia, links and do not version your API by any means + + +pass versions through headers / urls + + +I will not try to answer a question which approach is better. Whatever suit your needs and allows you to generate +business value should be picked. +Let’s assume that you do version your API. In that case you should provide as many contracts as many versions you support. +You can create a subfolder for every version or append it to th contract name - whatever suits you more. +
+
+JAR versioning +If by versioning you mean the version of the JAR that contains the stubs then there are essentially two main approaches. +Let’s assume that you’re doing Continuous Delivery / Deployment which means that you’re generating a new version of +the jar each time you go through the pipeline and that jar can go to production at any time. For example your jar version +looks like this (it got built on the 20.10.2016 at 20:15:21) : +1.0.0.20161020-201521-RELEASE +In that case your generated stub jar will look like this. +1.0.0.20161020-201521-RELEASE-stubs.jar +In this case you should inside your application.yml or @AutoConfigureStubRunner when referencing stubs provide the + latest version of the stubs. You can do that by passing the + sign. Example +@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"}) +If the versioning however is fixed (e.g. 1.0.4.RELEASE or 2.1.1) then you have to set the concrete value of the jar +version. Example for 2.1.1. +@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:2.1.1:stubs:8080"}) +
+
+Dev or prod stubs +You can manipulate the classifier to run the tests against current development version of the stubs of other services + or the ones that were deployed to production. If you alter your build to deploy the stubs with the prod-stubs classifier + once you reach production deployment then you can run tests in one case with dev stubs and one with prod stubs. +Example of tests using development version of stubs +@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"}) +Example of tests using production version of stubs +@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:prod-stubs:8080"}) +You can pass those values also via properties from your deployment pipeline. +
+
+
+Common repo with contracts +Another way of storing contracts other than having them with the producer is keeping them in a common place. +It can be related to security issues where the consumers can’t clone the producer’s code. Also if you keep +contracts in a single place then you, as a producer, will know how many consumers you have and which +consumer will you break with your local changes. +
+Repo structure +Let’s assume that we have a producer with coordinates com.example:server and 3 consumers: client1, +client2, client3. Then in the repository with common contracts you would have the following setup +(which you can checkout here: +├── com +│   └── example +│   └── server +│   ├── client1 +│   │   └── expectation.groovy +│   ├── client2 +│   │   └── expectation.groovy +│   ├── client3 +│   │   └── expectation.groovy +│   └── pom.xml +├── mvnw +├── mvnw.cmd +├── pom.xml +└── src + └── assembly + └── contracts.xml +As you can see the under the slash-delimited groupid / artifact id folder (com/example/server) you have +expectations of the 3 consumers (client1, client2 and client3). Expectations are the standard Groovy DSL +contract files as described throughout this documentation. This repository has to produce a JAR file that maps +one to one to the contents of the repo. +Example of a pom.xml inside the server folder. +<?xml version="1.0" encoding="UTF-8"?> +<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> + <modelVersion>4.0.0</modelVersion> + + <groupId>com.example</groupId> + <artifactId>server</artifactId> + <version>0.0.1-SNAPSHOT</version> + + <name>Server Stubs</name> + <description>POM used to install locally stubs for consumer side</description> + + <parent> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-starter-parent</artifactId> + <version>1.5.21.RELEASE</version> + <relativePath /> + </parent> + + <properties> + <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> + <java.version>1.8</java.version> + <spring-cloud-contract.version>1.2.8.BUILD-SNAPSHOT</spring-cloud-contract.version> + <spring-cloud-dependencies.version>1.3.11.BUILD-SNAPSHOT</spring-cloud-dependencies.version> + <excludeBuildFolders>true</excludeBuildFolders> + </properties> + + <dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${spring-cloud-dependencies.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> + </dependencyManagement> + + <build> + <plugins> + <plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <!-- By default it would search under src/test/resources/ --> + <contractsDirectory>${project.basedir}</contractsDirectory> + </configuration> + </plugin> + </plugins> + </build> + + <repositories> + <repository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </repository> + <repository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> + <repository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> + </repositories> + <pluginRepositories> + <pluginRepository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> + </pluginRepositories> + +</project> +As you can see there are no dependencies other than the Spring Cloud Contract Maven Plugin. +Those poms are necessary for the consumer side to run mvn clean install -DskipTests to locally install + stubs of the producer project. +The pom.xml in the root folder can look like this: +<?xml version="1.0" encoding="UTF-8"?> +<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> + <modelVersion>4.0.0</modelVersion> + + <groupId>com.example.standalone</groupId> + <artifactId>contracts</artifactId> + <version>0.0.1-SNAPSHOT</version> + + <name>Contracts</name> + <description>Contains all the Spring Cloud Contracts, well, contracts. JAR used by the producers to generate tests and stubs</description> + + <properties> + <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> + </properties> + + <build> + <plugins> + <plugin> + <groupId>org.apache.maven.plugins</groupId> + <artifactId>maven-assembly-plugin</artifactId> + <executions> + <execution> + <id>contracts</id> + <phase>prepare-package</phase> + <goals> + <goal>single</goal> + </goals> + <configuration> + <attach>true</attach> + <descriptor>${basedir}/src/assembly/contracts.xml</descriptor> + <!-- If you want an explicit classifier remove the following line --> + <appendAssemblyId>false</appendAssemblyId> + </configuration> + </execution> + </executions> + </plugin> + </plugins> + </build> + +</project> +It’s using the assembly plugin in order to build the JAR with all the contracts. Example of such setup is here: +<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3" + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd"> + <id>project</id> + <formats> + <format>jar</format> + </formats> + <includeBaseDirectory>false</includeBaseDirectory> + <fileSets> + <fileSet> + <directory>${project.basedir}</directory> + <outputDirectory>/</outputDirectory> + <useDefaultExcludes>true</useDefaultExcludes> + <excludes> + <exclude>**/${project.build.directory}/**</exclude> + <exclude>mvnw</exclude> + <exclude>mvnw.cmd</exclude> + <exclude>.mvn/**</exclude> + <exclude>src/**</exclude> + </excludes> + </fileSet> + </fileSets> +</assembly> +
+
+Workflow +The workflow would look similar to the one presented in the Step by step guide to CDC. The only difference + is that the producer doesn’t own the contracts anymore. So the consumer and the producer have to work on + common contracts in a common repository. +
+
+Consumer +When the consumer wants to work on the contracts offline, instead of cloning the producer code, the +consumer team clones the common repository, goes to the required producer’s folder (e.g. com/example/server) +and runs mvn clean install -DskipTests to install locally the stubs converted from the contracts. + +You need to have Maven installed locally + +
+
+Producer +As a producer it’s enough to alter the Spring Cloud Contract Verifier to provide the URL and the dependency +of the JAR containing the contracts: +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <configuration> + <contractsRepositoryUrl>http://link/to/your/nexus/or/artifactory/or/sth</contractsRepositoryUrl> + <contractDependency> + <groupId>com.example.standalone</groupId> + <artifactId>contracts</artifactId> + </contractDependency> + </configuration> +</plugin> +With this setup the JAR with groupid com.example.standalone and artifactid contracts will be downloaded +from http://link/to/your/nexus/or/artifactory/or/sth. It will be then unpacked in a local temporary folder +and contracts present under the com/example/server will be picked as the ones used to generate the +tests and the stubs. Due to this convention the producer team will know which consumer teams will be broken +when some incompatible changes are done. +The rest of the flow looks the same. +
+
+
+Can I have multiple base classes for tests? +Yes! Check out the Different base classes for contracts sections +of either Gradle or Maven plugins. +
+
+How can I debug the request/response being sent by the generated tests client? +The generated tests all boil down to RestAssured in some form or fashion which relies on Apache HttpClient. HttpClient has a facility called wire logging which logs the entire request and response to HttpClient. Spring Boot has a logging common application property for doing this sort of thing, just add this to your application properties +logging.level.org.apache.http.wire=DEBUG +
+How can I debug the mapping/request/response being sent by WireMock? +Starting from version 1.2.0 we turn on WireMock logging to +info and the WireMock notifier to being verbose. Now you will +exactly know what request was received by WireMock server and which +matching response definition was picked. +To turn off this feature just bump WireMock logging to ERROR +logging.level.com.github.tomakehurst.wiremock=ERROR +
+
+How can I see what got registered in the HTTP server stub? +You can use the mappingsOutputFolder property on @AutoConfigureStubRunner or StubRunnerRule +to dump all mappings per artifact id. Also the port at which the given stub server was +started will be attached. +
+
+Can I reference the request from the response? +Yes! With version 1.1.0 we’ve added such a possibility. On the HTTP stub server side we’re providing support +for this for WireMock. In case of other HTTP server stubs you’ll have to implement the approach yourself. +
+
+Can I reference text from file? +Yes! With version 1.2.0 we’ve added such a possibility. It’s enough to call file(…​) method in the +DSL and provide a path relative to where the contract lays. +If you’re using YAML just use the bodyFromFile property. +
+
+ + +Spring Cloud Contract Verifier Setup +You can set up Spring Cloud Contract Verifier in the following ways: + + +As a Gradle project + + +As a Maven project + + +As a Docker project + + +
+Gradle Project +To learn how to set up the Gradle project for Spring Cloud Contract Verifier, read the +following sections: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+Prerequisites +In order to use Spring Cloud Contract Verifier with WireMock, you muse use either a +Gradle or a Maven plugin. + +If you want to use Spock in your projects, you must add separately the +spock-core and spock-spring modules. Check Spock +docs for more information + +
+
+Add Gradle Plugin with Dependencies +To add a Gradle plugin with dependencies, use code similar to this: +buildscript { + repositories { + mavenCentral() + } + dependencies { + classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}" + classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}" + } +} + +apply plugin: 'groovy' +apply plugin: 'spring-cloud-contract' + +dependencyManagement { + imports { + mavenBom "org.springframework.cloud:spring-cloud-contract-dependencies:${verifier_version}" + } +} + +dependencies { + testCompile 'org.codehaus.groovy:groovy-all:2.4.6' + // example with adding Spock core and Spock Spring + testCompile 'org.spockframework:spock-core:1.0-groovy-2.4' + testCompile 'org.spockframework:spock-spring:1.0-groovy-2.4' + testCompile 'org.springframework.cloud:spring-cloud-starter-contract-verifier' +} +
+
+Gradle and Rest Assured 2.0 +By default, Rest Assured 3.x is added to the classpath. However, to use Rest Assured 2.x +you can add it to the plugins classpath, as shown here: +buildscript { + repositories { + mavenCentral() + } + dependencies { + classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}" + classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}" + classpath "com.jayway.restassured:rest-assured:2.5.0" + classpath "com.jayway.restassured:spring-mock-mvc:2.5.0" + } +} + +depenendencies { + // all dependencies + // you can exclude rest-assured from spring-cloud-contract-verifier + testCompile "com.jayway.restassured:rest-assured:2.5.0" + testCompile "com.jayway.restassured:spring-mock-mvc:2.5.0" +} +That way, the plugin automatically sees that Rest Assured 2.x is present on the classpath +and modifies the imports accordingly. +
+
+Snapshot Versions for Gradle +Add the additional snapshot repository to your build.gradle to use snapshot versions, +which are automatically uploaded after every successful build, as shown here: +buildscript { + repositories { + mavenCentral() + mavenLocal() + maven { url "https://repo.spring.io/snapshot" } + maven { url "https://repo.spring.io/milestone" } + maven { url "https://repo.spring.io/release" } + } +} +
+
+Add stubs +By default, Spring Cloud Contract Verifier is looking for stubs in the +src/test/resources/contracts directory. +The directory containing stub definitions is treated as a class name, and each stub +definition is treated as a single test. Spring Cloud Contract Verifier assumes that it +contains at least one level of directories that are to be used as the test class name. +If more than one level of nested directories is present, all except the last one is used +as the package name. For example, with following structure: +src/test/resources/contracts/myservice/shouldCreateUser.groovy +src/test/resources/contracts/myservice/shouldReturnUser.groovy +Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService +with two methods: + + +shouldCreateUser() + + +shouldReturnUser() + + +
+
+Run the Plugin +The plugin registers itself to be invoked before a check task. If you want it to be +part of your build process, you need to do nothing more. If you just want to generate +tests, invoke the generateContractTests task. +
+
+Default Setup +The default Gradle Plugin setup creates the following Gradle part of the build (in +pseudocode): +contracts { + targetFramework = 'JUNIT' + testMode = 'MockMvc' + generatedTestSourcesDir = project.file("${project.buildDir}/generated-test-sources/contracts") + contractsDslDir = "${project.rootDir}/src/test/resources/contracts" + basePackageForTests = 'org.springframework.cloud.verifier.tests' + stubsOutputDir = project.file("${project.buildDir}/stubs") + + // the following properties are used when you want to provide where the JAR with contract lays + contractDependency { + stringNotation = '' + } + contractsPath = '' + contractsWorkOffline = false + contractRepository { + cacheDownloadedContracts(true) + } +} + +tasks.create(type: Jar, name: 'verifierStubsJar', dependsOn: 'generateClientStubs') { + baseName = project.name + classifier = contracts.stubsSuffix + from contractVerifier.stubsOutputDir +} + +project.artifacts { + archives task +} + +tasks.create(type: Copy, name: 'copyContracts') { + from contracts.contractsDslDir + into contracts.stubsOutputDir +} + +verifierStubsJar.dependsOn 'copyContracts' + +publishing { + publications { + stubs(MavenPublication) { + artifactId project.name + artifact verifierStubsJar + } + } +} +
+
+Configure Plugin +To change the default configuration, add a contracts snippet to your Gradle config, as +shown here: +contracts { + testMode = 'MockMvc' + baseClassForTests = 'org.mycompany.tests' + generatedTestSourcesDir = project.file('src/generatedContract') +} +
+
+Configuration Options + + +testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, +which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to +Explicit for real HTTP calls. + + +imports: Creates an array with imports that should be included in generated tests +(for example ['org.myorg.Matchers']). By default, it creates an empty array. + + +staticImports: Creates an array with static imports that should be included in +generated tests(for example ['org.myorg.Matchers.*']). By default, it creates an empty +array. + + +basePackageForTests: Specifies the base package for all generated tests. If not set, +the value is picked from baseClassForTests’s package and from `packageWithBaseClasses. +If neither of these values are set, then the value is set to +org.springframework.cloud.contract.verifier.tests. + + +baseClassForTests: Creates a base class for all generated tests. By default, if you +use Spock classes, the class is spock.lang.Specification. + + +packageWithBaseClasses: Defines a package where all the base classes reside. This +setting takes precedence over baseClassForTests. + + +baseClassMappings: Explicitly maps a contract package to a FQN of a base class. This +setting takes precedence over packageWithBaseClasses and baseClassForTests. + + +ruleClassForTests: Specifies a rule that should be added to the generated test +classes. + + +ignoredFiles: Uses an Antmatcher to allow defining stub files for which processing +should be skipped. By default, it is an empty array. + + +contractsDslDir: Specifies the directory containing contracts written using the +GroovyDSL. By default, its value is $rootDir/src/test/resources/contracts. + + +generatedTestSourcesDir: Specifies the test source directory where tests generated +from the Groovy DSL should be placed. By default its value is +$buildDir/generated-test-sources/contractVerifier. + + +stubsOutputDir: Specifies the directory where the generated WireMock stubs from +the Groovy DSL should be placed. + + +targetFramework: Specifies the target test framework to be used. Currently, Spock and +JUnit are supported with JUnit being the default framework. + + +The following properties are used when you want to specify the location of the JAR +containing the contracts: +* contractDependency: Specifies the Dependency that provides +groupid:artifactid:version:classifier coordinates. You can use the contractDependency +closure to set it up. +* contractsPath: Specifies the path to the jar. If contract dependencies are + downloaded, the path defaults to groupid/artifactid where groupid is slash + separated. Otherwise, it scans contracts under the provided directory. +* contractsWorkOffline: Specifies whether to download the dependencies each time, so +that you can work online. In other words, it specifies whether to reuses the local Maven +repo. +
+
+Single Base Class for All Tests +When using Spring Cloud Contract Verifier in default MockMvc, you need to create a base +specification for all generated acceptance tests. In this class, you need to point to an +endpoint, which should be verified. +abstract class BaseMockMvcSpec extends Specification { + + def setup() { + RestAssuredMockMvc.standaloneSetup(new PairIdController()) + } + + void isProperCorrelationId(Integer correlationId) { + assert correlationId == 123456 + } + + void isEmpty(String value) { + assert value == null + } + +} +If you use Explicit mode, you can use a base class to initialize the whole tested app +as you might see in regular integration tests. If you use the JAXRSCLIENT mode, this +base class should also contain a protected WebTarget webTarget field. Right now, the +only option to test the JAX-RS API is to start a web server. +
+
+Different Base Classes for Contracts +If your base classes differ between contracts, you can tell the Spring Cloud Contract +plugin which class should get extended by the autogenerated tests. You have two options: + + +Follow a convention by providing the packageWithBaseClasses + + +Provide explicit mapping via baseClassMappings + + +By Convention +The convention is such that if you have a contract under (for example) +src/test/resources/contract/foo/bar/baz/ and set the value of the +packageWithBaseClasses property to com.example.base, then Spring Cloud Contract +Verifier assumes that there is a BarBazBase class under the com.example.base package. +In other words, the system takes the last two parts of the package, if they exist, and +forms a class with a Base suffix. This rule takes precedence over baseClassForTests. +Here is an example of how it works in the contracts closure: +packageWithBaseClasses = 'com.example.base' +By Mapping +You can manually map a regular expression of the contract’s package to fully qualified +name of the base class for the matched contract. You have to provide a list called +baseClassMappings that consists baseClassMapping objects that takes a +contractPackageRegex to baseClassFQN mapping. Consider the following example: +baseClassForTests = "com.example.FooBase" +baseClassMappings { + baseClassMapping('.*/com/.*', 'com.example.ComBase') + baseClassMapping('.*/bar/.*':'com.example.BarBase') +} +Let’s assume that you have contracts under + - src/test/resources/contract/com/ + - src/test/resources/contract/foo/ +By providing the baseClassForTests, we have a fallback in case mapping did not succeed. +(You could also provide the packageWithBaseClasses as a fallback.) That way, the tests +generated from src/test/resources/contract/com/ contracts extend the +com.example.ComBase, whereas the rest of the tests extend com.example.FooBase. +
+
+Invoking Generated Tests +To ensure that the provider side is compliant with defined contracts, you need to invoke: +./gradlew generateContractTests test +
+
+Spring Cloud Contract Verifier on the Consumer Side +In a consuming service, you need to configure the Spring Cloud Contract Verifier plugin +in exactly the same way as in case of provider. If you do not want to use Stub Runner +then you need to copy contracts stored in src/test/resources/contracts and generate +WireMock JSON stubs using: +./gradlew generateClientStubs + +The stubsOutputDir option has to be set for stub generation to work. + +When present, JSON stubs can be used in automated tests of consuming a service. +@ContextConfiguration(loader == SpringApplicationContextLoader, classes == Application) +class LoanApplicationServiceSpec extends Specification { + + @ClassRule + @Shared + WireMockClassRule wireMockRule == new WireMockClassRule() + + @Autowired + LoanApplicationService sut + + def 'should successfully apply for loan'() { + given: + LoanApplication application = + new LoanApplication(client: new Client(clientPesel: '12345678901'), amount: 123.123) + when: + LoanApplicationResult loanApplication == sut.loanApplication(application) + then: + loanApplication.loanApplicationStatus == LoanApplicationStatus.LOAN_APPLIED + loanApplication.rejectionReason == null + } +} +LoanApplication makes a call to FraudDetection service. This request is handled by a +WireMock server configured with stubs generated by Spring Cloud Contract Verifier. +
+
+
+Maven Project +To learn how to set up the Maven project for Spring Cloud Contract Verifier, read the +following sections: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+Add maven plugin +Add the Spring Cloud Contract BOM in a fashion similar to this: +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>${spring-cloud-dependencies.version}</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> +</dependencyManagement> +Next, add the Spring Cloud Contract Verifier Maven plugin: +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <packageWithBaseClasses>com.example.fraud</packageWithBaseClasses> + </configuration> +</plugin> +You can read more in the +Spring +Cloud Contract Maven Plugin Documentation. +
+
+Maven and Rest Assured 2.0 +By default, Rest Assured 3.x is added to the classpath. However, you can use Rest +Assured 2.x by adding it to the plugins classpath, as shown here: +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <packageWithBaseClasses>com.example</packageWithBaseClasses> + </configuration> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-verifier</artifactId> + <version>${spring-cloud-contract.version}</version> + </dependency> + <dependency> + <groupId>com.jayway.restassured</groupId> + <artifactId>rest-assured</artifactId> + <version>2.5.0</version> + <scope>compile</scope> + </dependency> + <dependency> + <groupId>com.jayway.restassured</groupId> + <artifactId>spring-mock-mvc</artifactId> + <version>2.5.0</version> + <scope>compile</scope> + </dependency> + </dependencies> +</plugin> + +<dependencies> + <!-- all dependencies --> + <!-- you can exclude rest-assured from spring-cloud-contract-verifier --> + <dependency> + <groupId>com.jayway.restassured</groupId> + <artifactId>rest-assured</artifactId> + <version>2.5.0</version> + <scope>test</scope> + </dependency> + <dependency> + <groupId>com.jayway.restassured</groupId> + <artifactId>spring-mock-mvc</artifactId> + <version>2.5.0</version> + <scope>test</scope> + </dependency> +</dependencies> +That way, the plugin automatically sees that Rest Assured 3.x is present on the classpath +and modifies the imports accordingly. +
+
+Snapshot versions for Maven +For Snapshot and Milestone versions, you have to add the following section to your +pom.xml, as shown here: +<repositories> + <repository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </repository> + <repository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> + <repository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> +</repositories> +<pluginRepositories> + <pluginRepository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> +</pluginRepositories> +
+
+Add stubs +By default, Spring Cloud Contract Verifier is looking for stubs in the +src/test/resources/contracts directory. The directory containing stub definitions is +treated as a class name, and each stub definition is treated as a single test. We assume +that it contains at least one directory to be used as test class name. If there is more +than one level of nested directories, all except the last one is used as package name. +For example, with following structure: +src/test/resources/contracts/myservice/shouldCreateUser.groovy +src/test/resources/contracts/myservice/shouldReturnUser.groovy +Spring Cloud Contract Verifier creates a test class named defaultBasePackage.MyService +with two methods + + +shouldCreateUser() + + +shouldReturnUser() + + +
+
+Run plugin +The plugin goal generateTests is assigned to be invoked in the phase called +generate-test-sources. If you want it to be part of your build process, you need not do +anything. If you just want to generate tests, invoke the generateTests goal. +
+
+Configure plugin +To change the default configuration, just add a configuration section to the plugin +definition or the execution definition, as shown here: +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <executions> + <execution> + <goals> + <goal>convert</goal> + <goal>generateStubs</goal> + <goal>generateTests</goal> + </goals> + </execution> + </executions> + <configuration> + <basePackageForTests>org.springframework.cloud.verifier.twitter.place</basePackageForTests> + <baseClassForTests>org.springframework.cloud.verifier.twitter.place.BaseMockMvcSpec</baseClassForTests> + </configuration> +</plugin> +
+
+Configuration Options + + +testMode: Defines the mode for acceptance tests. By default, the mode is MockMvc, +which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to +Explicit for real HTTP calls. + + +basePackageForTests: Specifies the base package for all generated tests. If not set, +the value is picked from baseClassForTests’s package and from `packageWithBaseClasses. +If neither of these values are set, then the value is set to +org.springframework.cloud.contract.verifier.tests. + + +ruleClassForTests: Specifies a rule that should be added to the generated test +classes. + + +baseClassForTests: Creates a base class for all generated tests. By default, if you +use Spock classes, the class is spock.lang.Specification. + + +contractsDirectory: Specifies a directory containing contracts written with the +GroovyDSL. The default directory is /src/test/resources/contracts. + + +testFramework: Specifies the target test framework to be used. Currently, Spock and +JUnit are supported with JUnit being the default framework + + +packageWithBaseClasses: Defines a package where all the base classes reside. This +setting takes precedence over baseClassForTests. The convention is such that, if you +have a contract under (for example) src/test/resources/contract/foo/bar/baz/ and set +the value of the packageWithBaseClasses property to com.example.base, then Spring +Cloud Contract Verifier assumes that there is a BarBazBase class under the +com.example.base package. In other words, the system takes the last two parts of the +package, if they exist, and forms a class with a Base suffix. + + +baseClassMappings: Specifies a list of base class mappings that provide +contractPackageRegex, which is checked against the package where the contract is +located, and baseClassFQN, which maps to the fully qualified name of the base class for +the matched contract. For example, if you have a contract under +src/test/resources/contract/foo/bar/baz/ and map the property +.* → com.example.base.BaseClass, then the test class generated from these contracts +extends com.example.base.BaseClass. This setting takes precedence over +packageWithBaseClasses and baseClassForTests. + + +If you want to download your contract definitions from a Maven repository, you can use +the following options: + + +contractDependency: The contract dependency that contains all the packaged contracts. + + +contractsPath: The path to the concrete contracts in the JAR with packaged contracts. +Defaults to groupid/artifactid where gropuid is slash separated. + + +contractsWorkOffline: Dictates whether the dependencies should be downloaded or the +local Maven artifacts should be reused. + + +contractsRepositoryUrl: URL to a repo with the artifacts that have contracts. If it is not provided, +use the current Maven ones. + + +contractsRepositoryUsername: The user name to be used to connect to the repo with contracts. + + +contractsRepositoryPassword: The password to be used to connect to the repo with contracts. + + +contractsRepositoryProxyHost: The proxy host to be used to connect to the repo with contracts. + + +contractsRepositoryProxyPort: The proxy port to be used to connect to the repo with contracts. + + +We cache only non-snapshot, explicitly provided versions (for example ++ or 1.0.0.BUILD-SNAPSHOT won’t get cached). By default, this feature is turned on. +
+
+Single Base Class for All Tests +When using Spring Cloud Contract Verifier in default MockMvc, you need to create a base +specification for all generated acceptance tests. In this class, you need to point to an +endpoint, which should be verified. +package org.mycompany.tests + +import org.mycompany.ExampleSpringController +import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc +import spock.lang.Specification + +class MvcSpec extends Specification { + def setup() { + RestAssuredMockMvc.standaloneSetup(new ExampleSpringController()) + } +} +If you use Explicit mode, you can use a base class to initialize the whole tested app +similarly, as you might find in regular integration tests. If you use the JAXRSCLIENT +mode, this base class should also contain a protected WebTarget webTarget field. Right +now, the only option to test the JAX-RS API is to start a web server. +
+
+Different base classes for contracts +If your base classes differ between contracts, you can tell the Spring Cloud Contract +plugin which class should get extended by the autogenerated tests. You have two options: + + +Follow a convention by providing the packageWithBaseClasses + + +provide explicit mapping via baseClassMappings + + +By Convention +The convention is such that if you have a contract under (for example) +src/test/resources/contract/foo/bar/baz/ and set the value of the +packageWithBaseClasses property to com.example.base, then Spring Cloud Contract +Verifier assumes that there is a BarBazBase class under the com.example.base package. +In other words, the system takes the last two parts of the package, if they exist, and +forms a class with a Base suffix. This rule takes precedence over baseClassForTests. +Here is an example of how it works in the contracts closure: +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <configuration> + <packageWithBaseClasses>hello</packageWithBaseClasses> + </configuration> +</plugin> +By Mapping +You can manually map a regular expression of the contract’s package to fully qualified +name of the base class for the matched contract. You have to provide a list called +baseClassMappings that consists baseClassMapping objects that takes a +contractPackageRegex to baseClassFQN mapping. Consider the following example: +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <configuration> + <baseClassForTests>com.example.FooBase</baseClassForTests> + <baseClassMappings> + <baseClassMapping> + <contractPackageRegex>.*com.*</contractPackageRegex> + <baseClassFQN>com.example.TestBase</baseClassFQN> + </baseClassMapping> + </baseClassMappings> + </configuration> +</plugin> +Assume that you have contracts under these two locations: +* src/test/resources/contract/com/ +* src/test/resources/contract/foo/ +By providing the baseClassForTests, we have a fallback in case mapping did not succeed. +(You can also provide the packageWithBaseClasses as a fallback.) That way, the tests +generated from src/test/resources/contract/com/ contracts extend the +com.example.ComBase, whereas the rest of the tests extend com.example.FooBase. +
+
+Invoking generated tests +The Spring Cloud Contract Maven Plugin generates verification code in a directory called +/generated-test-sources/contractVerifier and attaches this directory to testCompile +goal. +For Groovy Spock code, use the following: +<plugin> + <groupId>org.codehaus.gmavenplus</groupId> + <artifactId>gmavenplus-plugin</artifactId> + <version>1.5</version> + <executions> + <execution> + <goals> + <goal>testCompile</goal> + </goals> + </execution> + </executions> + <configuration> + <testSources> + <testSource> + <directory>${project.basedir}/src/test/groovy</directory> + <includes> + <include>**/*.groovy</include> + </includes> + </testSource> + <testSource> + <directory>${project.build.directory}/generated-test-sources/contractVerifier</directory> + <includes> + <include>**/*.groovy</include> + </includes> + </testSource> + </testSources> + </configuration> +</plugin> +To ensure that provider side is compliant with defined contracts, you need to invoke +mvn generateTest test. +
+
+Maven Plugin and STS +If you see the following exception while using STS: + + + + + +STS Exception + + +When you click on the error marker you should see something like this: + plugin:1.1.0.M1:convert:default-convert:process-test-resources) org.apache.maven.plugin.PluginExecutionException: Execution default-convert of goal org.springframework.cloud:spring- + cloud-contract-maven-plugin:1.1.0.M1:convert failed. at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145) at + org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331) at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362) at +... + org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.lang.NullPointerException at + org.eclipse.m2e.core.internal.builder.plexusbuildapi.EclipseIncrementalBuildContext.hasDelta(EclipseIncrementalBuildContext.java:53) at + org.sonatype.plexus.build.incremental.ThreadBuildContext.hasDelta(ThreadBuildContext.java:59) at +In order to fix this issue, provide the following section in your pom.xml: +<build> + <pluginManagement> + <plugins> + <!--This plugin's configuration is used to store Eclipse m2e settings + only. It has no influence on the Maven build itself. --> + <plugin> + <groupId>org.eclipse.m2e</groupId> + <artifactId>lifecycle-mapping</artifactId> + <version>1.0.0</version> + <configuration> + <lifecycleMappingMetadata> + <pluginExecutions> + <pluginExecution> + <pluginExecutionFilter> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <versionRange>[1.0,)</versionRange> + <goals> + <goal>convert</goal> + </goals> + </pluginExecutionFilter> + <action> + <execute /> + </action> + </pluginExecution> + </pluginExecutions> + </lifecycleMappingMetadata> + </configuration> + </plugin> + </plugins> + </pluginManagement> +</build> +
+
+
+Stubs and Transitive Dependencies +The Maven and Gradle plugin that add the tasks that create the stubs jar for you. One +problem that arises is that, when reusing the stubs, you can mistakenly import all of +that stub’s dependencies. When building a Maven artifact, even though you have a couple +of different jars, all of them share one pom: +├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar +├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar.sha1 +├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar +├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar.sha1 +├── github-webhook-0.0.1.BUILD-SNAPSHOT.jar +├── github-webhook-0.0.1.BUILD-SNAPSHOT.pom +├── github-webhook-0.0.1.BUILD-SNAPSHOT-stubs.jar +├── ... +└── ... +There are three possibilities of working with those dependencies so as not to have any +issues with transitive dependencies: + + +Mark all application dependencies as optional + + +Create a separate artifactid for the stubs + + +Exclude dependencies on the consumer side + + +Mark all application dependencies as optional +If, in the github-webhook application, you mark all of your dependencies as optional, +when you include the github-webhook stubs in another application (or when that +dependency gets downloaded by Stub Runner) then, since all of the dependencies are +optional, they will not get downloaded. +Create a separate artifactid for the stubs +If you create a separate artifactid, then you can set it up in whatever way you wish. +For example, you might decide to have no dependencies at all. +Exclude dependencies on the consumer side +As a consumer, if you add the stub dependency to your classpath, you can explicitly +exclude the unwanted dependencies. +
+
+CI Server setup +When fetching stubs / contracts in a CI, shared environment, what might happen is that +both the producer and the consumer reuse the same local Maven repository. Due to this, +the framework, responsible for downloading a stub JAR from remote location, +can’t decide which JAR should be picked, local or remote one. That caused +the "The artifact was found in the local repository but you have explicitly +stated that it should be downloaded from a remote one" exception +and failed the build. +For such cases we’re introducing the property mechanism: + + +via stubrunner.snapshot-check-skip system property + + +via STUBRUNNER_SNAPSHOT_CHECK_SKIP environment variable + + +if either of these values is set to true, then the stub downloader will not +verify the origin of the downloaded JAR. +
+
+Scenarios +You can handle scenarios with Spring Cloud Contract Verifier. All you need to do is to +stick to the proper naming convention while creating your contracts. The convention +requires including an order number followed by an underscore. This will work regardles + of whether you’re working with YAML or Groovy. Example: +my_contracts_dir\ + scenario1\ + 1_login.groovy + 2_showCart.groovy + 3_logout.groovy +Such a tree causes Spring Cloud Contract Verifier to generate WireMock’s scenario with a +name of scenario1 and the three following steps: + + +login marked as Started pointing to…​ + + +showCart marked as Step1 pointing to…​ + + +logout marked as Step2 which will close the scenario. + + +More details about WireMock scenarios can be found at +https://wiremock.org/stateful-behaviour.html +Spring Cloud Contract Verifier also generates tests with a guaranteed order of execution. +
+
+Docker Project +We’re publishing a springcloud/spring-cloud-contract Docker image +that contains a project that will generate tests and execute them in EXPLICIT mode +against a running application. + +The EXPLICIT mode means that the tests generated from contracts will send +real requests and not the mocked ones. + +
+Short intro to Maven, JARs and Binary storage +Since the Docker image can be used by non JVM projects, it’s good to +explain the basic terms behind Spring Cloud Contract packaging defaults. +Part of the following definitions were taken from the Maven Glossary + + +Project: Maven thinks in terms of projects. Everything that you +will build are projects. Those projects follow a well defined +“Project Object Model”. Projects can depend on other projects, +in which case the latter are called “dependencies”. A project may +consistent of several subprojects, however these subprojects are still +treated equally as projects. + + +Artifact: An artifact is something that is either produced or used +by a project. Examples of artifacts produced by Maven for a project +include: JARs, source and binary distributions. Each artifact +is uniquely identified by a group id and an artifact ID which is +unique within a group. + + +JAR: JAR stands for Java ARchive. It’s a format based on +the ZIP file format. Spring Cloud Contract packages the contracts and generated +stubs in a JAR file. + + +GroupId: A group ID is a universally unique identifier for a project. +While this is often just the project name (eg. commons-collections), +it is helpful to use a fully-qualified package name to distinguish it +from other projects with a similar name (eg. org.apache.maven). +Typically, when published to the Artifact Manager, the GroupId will get +slash separated and form part of the URL. E.g. for group id com.example +and artifact id application would be /com/example/application/. + + +Classifier: The Maven dependency notation looks as follows: +groupId:artifactId:version:classifier. The classifier is additional suffix +passed to the dependency. E.g. stubs, sources. The same dependency +e.g. com.example:application can produce multiple artifacts that +differ from each other with the classifier. + + +Artifact manager: When you generate binaries / sources / packages, you would +like them to be available for others to download / reference or reuse. In case +of the JVM world those artifacts would be JARs, for Ruby these are gems +and for Docker those would be Docker images. You can store those artifacts +in a manager. Examples of such managers can be Artifactory +or Nexus. + + +
+
+How it works +The image searches for contracts under the /contracts folder. +The output from running the tests will be available under +/spring-cloud-contract/build folder (it’s useful for debugging +purposes). +It’s enough for you to mount your contracts, pass the environment variables + and the image will: + + +generate the contract tests + + +execute the tests against the provided URL + + +generate the WireMock stubs + + +(optional - turned on by default) publish the stubs to a Artifact Manager + + +
+Environment Variables +The Docker image requires some environment variables to point to +your running application, to the Artifact manager instance etc. + + +PROJECT_GROUP - your project’s group id. Defaults to com.example + + +PROJECT_VERSION - your project’s version. Defaults to 0.0.1-SNAPSHOT + + +PROJECT_NAME - artifact id. Defaults to example + + +REPO_WITH_BINARIES_URL - URL of your Artifact Manager. Defaults to http://localhost:8081/artifactory/libs-release-local +which is the default URL of Artifactory running locally + + +REPO_WITH_BINARIES_USERNAME - (optional) username when the Artifact Manager is secured + + +REPO_WITH_BINARIES_PASSWORD - (optional) password when the Artifact Manager is secured + + +PUBLISH_ARTIFACTS - if set to true then will publish artifact to binary storage. Defaults to true. + + +These environment variables are used when contracts lay in an external repository. To enable +this feature you must set the EXTERNAL_CONTRACTS_ARTIFACT_ID environment variable. + + +EXTERNAL_CONTRACTS_GROUP_ID - group id of the project with contracts. Defaults to com.example + + +EXTERNAL_CONTRACTS_ARTIFACT_ID- artifact id of the project with contracts. + + +EXTERNAL_CONTRACTS_CLASSIFIER- classifier of the project with contracts. Empty by default + + +EXTERNAL_CONTRACTS_VERSION - version of the project with contracts. Defaults to +, equivalent to picking the latest + + +EXTERNAL_CONTRACTS_REPO_WITH_BINARIES_URL - URL of your Artifact Manager. Defaults to value of REPO_WITH_BINARIES_URL env var. +If that’s not set, defaults to http://localhost:8081/artifactory/libs-release-local +which is the default URL of Artifactory running locally + + +EXTERNAL_CONTRACTS_PATH - path to contracts for the given project, inside the project with contracts. +Defaults to slash separated EXTERNAL_CONTRACTS_GROUP_ID concatenated with / and EXTERNAL_CONTRACTS_ARTIFACT_ID. E.g. +for group id foo.bar and artifact id baz, would result in foo/bar/baz contracts path. + + +EXTERNAL_CONTRACTS_WORK_OFFLINE - if set to true then will retrieve artifact with contracts +from the container’s .m2. Mount your local .m2 as a volume available at the container’s /root/.m2 path. +You must not set both EXTERNAL_CONTRACTS_WORK_OFFLINE and EXTERNAL_CONTRACTS_REPO_WITH_BINARIES_URL. + + +These environment variables are used when tests are executed: + + +APPLICATION_BASE_URL - url against which tests should be executed. +Remember that it has to be accessible from the Docker container (e.g. localhost +will not work) + + +APPLICATION_USERNAME - (optional) username for basic authentication to your application + + +APPLICATION_PASSWORD - (optional) password for basic authentication to your application + + +
+
+
+Example of usage +Let’s take a look at a simple MVC application +$ git clone https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs +$ cd bookstore +The contracts are available under /contracts folder. +
+
+Server side (nodejs) +Since we want to run tests, we could just execute: +$ npm test +however, for learning purposes, let’s split it into pieces: +# Stop docker infra (nodejs, artifactory) +$ ./stop_infra.sh +# Start docker infra (nodejs, artifactory) +$ ./setup_infra.sh + +# Kill & Run app +$ pkill -f "node app" +$ nohup node app & + +# Prepare environment variables +$ SC_CONTRACT_DOCKER_VERSION="..." +$ APP_IP="192.168.0.100" +$ APP_PORT="3000" +$ ARTIFACTORY_PORT="8081" +$ APPLICATION_BASE_URL="http://${APP_IP}:${APP_PORT}" +$ ARTIFACTORY_URL="http://${APP_IP}:${ARTIFACTORY_PORT}/artifactory/libs-release-local" +$ CURRENT_DIR="$( pwd )" +$ CURRENT_FOLDER_NAME=${PWD##*/} +$ PROJECT_VERSION="0.0.1.RELEASE" + +# Execute contract tests +$ docker run --rm -e "APPLICATION_BASE_URL=${APPLICATION_BASE_URL}" -e "PUBLISH_ARTIFACTS=true" -e "PROJECT_NAME=${CURRENT_FOLDER_NAME}" -e "REPO_WITH_BINARIES_URL=${ARTIFACTORY_URL}" -e "PROJECT_VERSION=${PROJECT_VERSION}" -v "${CURRENT_DIR}/contracts/:/contracts:ro" -v "${CURRENT_DIR}/node_modules/spring-cloud-contract/output:/spring-cloud-contract-output/" springcloud/spring-cloud-contract:"${SC_CONTRACT_DOCKER_VERSION}" + +# Kill app +$ pkill -f "node app" +What will happen is that via bash scripts: + + +infrastructure will be set up (MongoDb, Artifactory). +In real life scenario you would just run the NodeJS application +with mocked database. In this example we want to show how we can +benefit from Spring Cloud Contract in no time. + + +due to those constraints the contracts also represent the +stateful situation + + +first request is a POST that causes data to get inserted to the database + + +second request is a GET that returns a list of data with 1 previously inserted element + + + + +the NodeJS application will be started (on port 3000) + + +contract tests will be generated via Docker and tests +will be executed against the running application + + +the contracts will be taken from /contracts folder. + + +the output of the test execution is available under +node_modules/spring-cloud-contract/output. + + + + +the stubs will be uploaded to Artifactory. You can check them out +under http://localhost:8081/artifactory/libs-release-local/com/example/bookstore/0.0.1.RELEASE/ . +The stubs will be here http://localhost:8081/artifactory/libs-release-local/com/example/bookstore/0.0.1.RELEASE/bookstore-0.0.1.RELEASE-stubs.jar. + + +To see how the client side looks like check out the section. +
+
+ + +Spring Cloud Contract Verifier Messaging +Spring Cloud Contract Verifier lets you verify applications that uses messaging as a +means of communication. All of the integrations shown in this document work with Spring, +but you can also create one of your own and use that. +
+Integrations +You can use one of the following four integration configurations: + + +Apache Camel + + +Spring Integration + + +Spring Cloud Stream + + +Spring AMQP + + +Since we use Spring Boot, if you have added one of these libraries to the classpath, all +the messaging configuration is automatically set up. + +Remember to put @AutoConfigureMessageVerifier on the base class of your +generated tests. Otherwise, messaging part of Spring Cloud Contract Verifier does not +work. + + +If you want to use Spring Cloud Stream, remember to add a dependency on +org.springframework.cloud:spring-cloud-stream-test-support, as shown here: + + +Maven + +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-test-support</artifactId> + <scope>test</scope> +</dependency> + + + +Gradle + +testCompile "org.springframework.cloud:spring-cloud-stream-test-support" + + +
+
+Manual Integration Testing +The main interface used by the tests is +org.springframework.cloud.contract.verifier.messaging.MessageVerifier. +It defines how to send and receive messages. You can create your own implementation to +achieve the same goal. +In a test, you can inject a ContractVerifierMessageExchange to send and receive +messages that follow the contract. Then add @AutoConfigureMessageVerifier to your test. +Here’s an example: +@RunWith(SpringTestRunner.class) +@SpringBootTest +@AutoConfigureMessageVerifier +public static class MessagingContractTests { + + @Autowired + private MessageVerifier verifier; + ... +} + +If your tests require stubs as well, then @AutoConfigureStubRunner includes the +messaging configuration, so you only need the one annotation. + +
+
+Publisher-Side Test Generation +Having the input or outputMessage sections in your DSL results in creation of tests +on the publisher’s side. By default, JUnit tests are created. However, there is also a +possibility to create Spock tests. +There are 3 main scenarios that we should take into consideration: + + +Scenario 1: There is no input message that produces an output message. The output +message is triggered by a component inside the application (for example, scheduler). + + +Scenario 2: The input message triggers an output message. + + +Scenario 3: The input message is consumed and there is no output message. + + + +The destination passed to messageFrom or sentTo can have different +meanings for different messaging implementations. For Stream and Integration it is +first resolved as a destination of a channel. Then, if there is no such destination +it is resolved as a channel name. For Camel, that’s a certain component (for example, +jms). + +
+Scenario 1: No Input Message +Here is an example for Camel. For the given contract: + +Groovy DSL + +def contractDsl = Contract.make { + label 'some_label' + input { + triggeredBy('bookReturnedTriggered()') + } + outputMessage { + sentTo('activemq:output') + body('''{ "bookName" : "foo" }''') + headers { + header('BOOK-NAME', 'foo') + messagingContentType(applicationJson()) + } + } +} + + + +YAML + +label: some_label +input: + triggeredBy: bookReturnedTriggered +outputMessage: + sentTo: activemq:output + body: + bookName: foo + headers: + BOOK-NAME: foo + contentType: application/json + + +The following JUnit test is created: +''' + // when: + bookReturnedTriggered(); + + // then: + ContractVerifierMessage response = contractVerifierMessaging.receive("activemq:output"); + assertThat(response).isNotNull(); + assertThat(response.getHeader("BOOK-NAME")).isNotNull(); + assertThat(response.getHeader("BOOK-NAME").toString()).isEqualTo("foo"); + assertThat(response.getHeader("contentType")).isNotNull(); + assertThat(response.getHeader("contentType").toString()).isEqualTo("application/json"); + // and: + DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload())); + assertThatJson(parsedJson).field("bookName").isEqualTo("foo"); +''' +And the following Spock test would be created: +''' + when: + bookReturnedTriggered() + + then: + ContractVerifierMessage response = contractVerifierMessaging.receive('activemq:output') + assert response != null + response.getHeader('BOOK-NAME')?.toString() == 'foo' + response.getHeader('contentType')?.toString() == 'application/json' + and: + DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload)) + assertThatJson(parsedJson).field("bookName").isEqualTo("foo") + +''' +
+
+Scenario 2: Output Triggered by Input +Here is an example for Camel. For the given contract: + +Groovy DSL + +def contractDsl = Contract.make { + label 'some_label' + input { + messageFrom('jms:input') + messageBody([ + bookName: 'foo' + ]) + messageHeaders { + header('sample', 'header') + } + } + outputMessage { + sentTo('jms:output') + body([ + bookName: 'foo' + ]) + headers { + header('BOOK-NAME', 'foo') + } + } +} + + + +YAML + +label: some_label +input: + messageFrom: jms:input + messageBody: + bookName: 'foo' + messageHeaders: + sample: header +outputMessage: + sentTo: jms:output + body: + bookName: foo + headers: + BOOK-NAME: foo + + +The following JUnit test is created: +''' +// given: + ContractVerifierMessage inputMessage = contractVerifierMessaging.create( + "{\\"bookName\\":\\"foo\\"}" +, headers() + .header("sample", "header")); + +// when: + contractVerifierMessaging.send(inputMessage, "jms:input"); + +// then: + ContractVerifierMessage response = contractVerifierMessaging.receive("jms:output"); + assertThat(response).isNotNull(); + assertThat(response.getHeader("BOOK-NAME")).isNotNull(); + assertThat(response.getHeader("BOOK-NAME").toString()).isEqualTo("foo"); +// and: + DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload())); + assertThatJson(parsedJson).field("bookName").isEqualTo("foo"); +''' +And the following Spock test would be created: +"""\ +given: + ContractVerifierMessage inputMessage = contractVerifierMessaging.create( + '''{"bookName":"foo"}''', + ['sample': 'header'] + ) + +when: + contractVerifierMessaging.send(inputMessage, 'jms:input') + +then: + ContractVerifierMessage response = contractVerifierMessaging.receive('jms:output') + assert response !- null + response.getHeader('BOOK-NAME')?.toString() == 'foo' +and: + DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload)) + assertThatJson(parsedJson).field("bookName").isEqualTo("foo") +""" +
+
+Scenario 3: No Output Message +Here is an example for Camel. For the given contract: + +Groovy DSL + +def contractDsl = Contract.make { + label 'some_label' + input { + messageFrom('jms:delete') + messageBody([ + bookName: 'foo' + ]) + messageHeaders { + header('sample', 'header') + } + assertThat('bookWasDeleted()') + } +} + + + +YAML + +label: some_label +input: + messageFrom: jms:delete + messageBody: + bookName: 'foo' + messageHeaders: + sample: header + assertThat: bookWasDeleted() + + +The following JUnit test is created: +''' +// given: + ContractVerifierMessage inputMessage = contractVerifierMessaging.create( + "{\\"bookName\\":\\"foo\\"}" +, headers() + .header("sample", "header")); + +// when: + contractVerifierMessaging.send(inputMessage, "jms:delete"); + +// then: + bookWasDeleted(); +''' +And the following Spock test would be created: +''' +given: + ContractVerifierMessage inputMessage = contractVerifierMessaging.create( + \'\'\'{"bookName":"foo"}\'\'\', + ['sample': 'header'] + ) + +when: + contractVerifierMessaging.send(inputMessage, 'jms:delete') + +then: + noExceptionThrown() + bookWasDeleted() +''' +
+
+
+Consumer Stub Generation +Unlike the HTTP part, in messaging, we need to publish the Groovy DSL inside the JAR with +a stub. Then it is parsed on the consumer side and proper stubbed routes are created. +For more information, see +the +Stub Runner Messaging sections. + +Maven + +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-stream-rabbit</artifactId> + </dependency> + + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-contract-stub-runner</artifactId> + <scope>test</scope> + </dependency> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-test-support</artifactId> + <scope>test</scope> + </dependency> +</dependencies> + +<dependencyManagement> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-dependencies</artifactId> + <version>Edgware.BUILD-SNAPSHOT</version> + <type>pom</type> + <scope>import</scope> + </dependency> + </dependencies> +</dependencyManagement> + + + +Gradle + +ext { + contractsDir = file("mappings") + stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/") +} + +// Automatically added by plugin: +// copyContracts - copies contracts to the output folder from which JAR will be created +// verifierStubsJar - JAR with a provided stub suffix +// the presented publication is also added by the plugin but you can modify it as you wish + +publishing { + publications { + stubs(MavenPublication) { + artifactId "${project.name}-stubs" + artifact verifierStubsJar + } + } +} + + +
+ + +Spring Cloud Contract Stub Runner +One of the issues that you might encounter while using Spring Cloud Contract Verifier is +passing the generated WireMock JSON stubs from the server side to the client side (or to +various clients). The same takes place in terms of client-side generation for messaging. +Copying the JSON files and setting the client side for messaging manually is out of the +question. That is why we introduced Spring Cloud Contract Stub Runner. It can +automatically download and run the stubs for you. +
+Snapshot versions +Add the additional snapshot repository to your build.gradle file to use snapshot +versions, which are automatically uploaded after every successful build: + +Maven + +<repositories> + <repository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </repository> + <repository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> + <repository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </repository> +</repositories> +<pluginRepositories> + <pluginRepository> + <id>spring-snapshots</id> + <name>Spring Snapshots</name> + <url>https://repo.spring.io/snapshot</url> + <snapshots> + <enabled>true</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-milestones</id> + <name>Spring Milestones</name> + <url>https://repo.spring.io/milestone</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> + <pluginRepository> + <id>spring-releases</id> + <name>Spring Releases</name> + <url>https://repo.spring.io/release</url> + <snapshots> + <enabled>false</enabled> + </snapshots> + </pluginRepository> +</pluginRepositories> + + + +Gradle + +buildscript { + repositories { + mavenCentral() + mavenLocal() + maven { url "https://repo.spring.io/snapshot" } + maven { url "https://repo.spring.io/milestone" } + maven { url "https://repo.spring.io/release" } + } + + +
+
+Publishing Stubs as JARs +The easiest approach would be to centralize the way stubs are kept. For example, you can +keep them as jars in a Maven repository. + +For both Maven and Gradle, the setup comes ready to work. However, you can customize +it if you want to. + + +Maven + +<!-- First disable the default jar setup in the properties section --> +<!-- we don't want the verifier to do a jar for us --> +<spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip> + +<!-- Next add the assembly plugin to your build --> +<!-- we want the assembly plugin to generate the JAR --> +<plugin> + <groupId>org.apache.maven.plugins</groupId> + <artifactId>maven-assembly-plugin</artifactId> + <executions> + <execution> + <id>stub</id> + <phase>prepare-package</phase> + <goals> + <goal>single</goal> + </goals> + <inherited>false</inherited> + <configuration> + <attach>true</attach> + <descriptors> + $../../../../src/assembly/stub.xml + </descriptors> + </configuration> + </execution> + </executions> +</plugin> + +<!-- Finally setup your assembly. Below you can find the contents of src/main/assembly/stub.xml --> +<assembly + xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3" + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd"> + <id>stubs</id> + <formats> + <format>jar</format> + </formats> + <includeBaseDirectory>false</includeBaseDirectory> + <fileSets> + <fileSet> + <directory>src/main/java</directory> + <outputDirectory>/</outputDirectory> + <includes> + <include>**com/example/model/*.*</include> + </includes> + </fileSet> + <fileSet> + <directory>${project.build.directory}/classes</directory> + <outputDirectory>/</outputDirectory> + <includes> + <include>**com/example/model/*.*</include> + </includes> + </fileSet> + <fileSet> + <directory>${project.build.directory}/snippets/stubs</directory> + <outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/mappings</outputDirectory> + <includes> + <include>**/*</include> + </includes> + </fileSet> + <fileSet> + <directory>$../../../../src/test/resources/contracts</directory> + <outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/contracts</outputDirectory> + <includes> + <include>**/*.groovy</include> + </includes> + </fileSet> + </fileSets> +</assembly> + + + +Gradle + +ext { + contractsDir = file("mappings") + stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/") +} + +// Automatically added by plugin: +// copyContracts - copies contracts to the output folder from which JAR will be created +// verifierStubsJar - JAR with a provided stub suffix +// the presented publication is also added by the plugin but you can modify it as you wish + +publishing { + publications { + stubs(MavenPublication) { + artifactId "${project.name}-stubs" + artifact verifierStubsJar + } + } +} + + +
+
+Stub Runner Core +Runs stubs for service collaborators. Treating stubs as contracts of services allows to use stub-runner as an implementation of +Consumer Driven Contracts. +Stub Runner allows you to automatically download the stubs of the provided dependencies (or pick those from the classpath), start WireMock servers for them and feed them with proper stub definitions. +For messaging, special stub routes are defined. +
+Retrieving stubs +You can pick the following options of acquiring stubs + + +Aether based solution that downloads JARs with stubs from Artifactory / Nexus + + +Classpath scanning solution that searches classpath via pattern to retrieve stubs + + +Write your own implementation of the org.springframework.cloud.contract.stubrunner.StubDownloaderBuilder for full customization + + +The latter example is described in the Custom Stub Runner section. +
+Stub downloading +If you provide the stubrunner.repositoryRoot or stubrunner.workOffline flag will be set +to true then Stub Runner will connect to the given server and download the required jars. +It will then unpack the JAR to a temporary folder and reference those files in further +contract processing. +Example: +@AutoConfigureStubRunner(repositoryRoot="https://foo.bar", ids = "com.example:beer-api-producer:+:stubs:8095") +
+
+Classpath scanning +If you DON’T provide the stubrunner.repositoryRoot and stubrunner.workOffline flag will +be set to false (that’s the default) then classpath will get scanned. Let’s look at the +following example: +@AutoConfigureStubRunner(ids = { + "com.example:beer-api-producer:+:stubs:8095", + "com.example.foo:bar:1.0.0:superstubs:8096" +}) +If you’ve added the dependencies to your classpath + +Maven + +<dependency> + <groupId>com.example</groupId> + <artifactId>beer-api-producer-restdocs</artifactId> + <classifier>stubs</classifier> + <version>0.0.1-SNAPSHOT</version> + <scope>test</scope> + <exclusions> + <exclusion> + <groupId>*</groupId> + <artifactId>*</artifactId> + </exclusion> + </exclusions> +</dependency> +<dependency> + <groupId>com.example.foo</groupId> + <artifactId>bar</artifactId> + <classifier>superstubs</classifier> + <version>1.0.0</version> + <scope>test</scope> + <exclusions> + <exclusion> + <groupId>*</groupId> + <artifactId>*</artifactId> + </exclusion> + </exclusions> +</dependency> + + + +Gradle + +testCompile("com.example:beer-api-producer-restdocs:0.0.1-SNAPSHOT:stubs") { + transitive = false +} +testCompile("com.example.foo:bar:1.0.0:superstubs") { + transitive = false +} + + +Then the following locations on your classpath will get scanned. For com.example:beer-api-producer-restdocs + + +/META-INF/com.example/beer-api-producer-restdocs/*/.* + + +/contracts/com.example/beer-api-producer-restdocs/*/.* + + +/mappings/com.example/beer-api-producer-restdocs/*/.* + + +and com.example.foo:bar + + +/META-INF/com.example.foo/bar/*/.* + + +/contracts/com.example.foo/bar/*/.* + + +/mappings/com.example.foo/bar/*/.* + + + +As you can see you have to explicitly provide the group and artifact ids when packaging the +producer stubs. + +The producer would setup the contracts like this: +└── src + └── test + └── resources + └── contracts +    └── com.example +       └── beer-api-producer-restdocs +       └── nested +       └── contract3.groovy +To achieve proper stub packaging. +Or using the Maven assembly plugin or +Gradle Jar task you have to create the following +structure in your stubs jar. +└── META-INF + └── com.example + └── beer-api-producer-restdocs + └── 2.0.0 + ├── contracts + │   └── nested +    │ └── contract2.groovy +    └── mappings +    └── mapping.json +By maintaining this structure classpath gets scanned and you can profit from the messaging / +HTTP stubs without the need to download artifacts. +
+
+
+Running stubs +
+Running using main app +You can set the following options to the main class: +-c, --classifier Suffix for the jar containing stubs (e. + g. 'stubs' if the stub jar would + have a 'stubs' classifier for stubs: + foobar-stubs ). Defaults to 'stubs' + (default: stubs) +--maxPort, --maxp <Integer> Maximum port value to be assigned to + the WireMock instance. Defaults to + 15000 (default: 15000) +--minPort, --minp <Integer> Minimum port value to be assigned to + the WireMock instance. Defaults to + 10000 (default: 10000) +-p, --password Password to user when connecting to + repository +--phost, --proxyHost Proxy host to use for repository + requests +--pport, --proxyPort [Integer] Proxy port to use for repository + requests +-r, --root Location of a Jar containing server + where you keep your stubs (e.g. http: + //nexus. + net/content/repositories/repository) +-s, --stubs Comma separated list of Ivy + representation of jars with stubs. + Eg. groupid:artifactid1,groupid2: + artifactid2:classifier +-u, --username Username to user when connecting to + repository +--wo, --workOffline Switch to work offline. Defaults to + 'false' +
+
+HTTP Stubs +Stubs are defined in JSON documents, whose syntax is defined in WireMock documentation +Example: +{ + "request": { + "method": "GET", + "url": "/ping" + }, + "response": { + "status": 200, + "body": "pong", + "headers": { + "Content-Type": "text/plain" + } + } +} +
+
+Viewing registered mappings +Every stubbed collaborator exposes list of defined mappings under __/admin/ endpoint. +You can also use the mappingsOutputFolder property to dump the mappings to files. + For annotation based approach it would look like this +@AutoConfigureStubRunner(ids="a.b.c:loanIssuance,a.b.c:fraudDetectionServer", +mappingsOutputFolder = "target/outputmappings/") +and for the JUnit approach like this: +@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule() + .repoRoot("http://some_url") + .downloadStub("a.b.c", "loanIssuance") + .downloadStub("a.b.c:fraudDetectionServer") + .withMappingsOutputFolder("target/outputmappings") +Then if you check out the folder target/outputmappings you would see the following structure +. +├── fraudDetectionServer_13705 +└── loanIssuance_12255 +That means that there were two stubs registered. fraudDetectionServer was registered at port 13705 +and loanIssuance at port 12255. If we take a look at one of the files we would see (for WireMock) +mappings available for the given server: +[{ + "id" : "f9152eb9-bf77-4c38-8289-90be7d10d0d7", + "request" : { + "url" : "/name", + "method" : "GET" + }, + "response" : { + "status" : 200, + "body" : "fraudDetectionServer" + }, + "uuid" : "f9152eb9-bf77-4c38-8289-90be7d10d0d7" +}, +... +] +
+
+Messaging Stubs +Depending on the provided Stub Runner dependency and the DSL the messaging routes are automatically set up. +
+
+
+
+Stub Runner JUnit Rule +Stub Runner comes with a JUnit rule thanks to which you can very easily download and run stubs for given group and artifact id: +@ClassRule public static StubRunnerRule rule = new StubRunnerRule() + .repoRoot(repoRoot()) + .downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance") + .downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer"); +After that rule gets executed Stub Runner connects to your Maven repository and for the given list of dependencies tries to: + + +download them + + +cache them locally + + +unzip them to a temporary folder + + +start a WireMock server for each Maven dependency on a random port from the provided range of ports / provided port + + +feed the WireMock server with all JSON files that are valid WireMock definitions + + +can also send messages (remember to pass an implementation of MessageVerifier interface) + + +Stub Runner uses Eclipse Aether mechanism to download the Maven dependencies. +Check their docs for more information. +Since the StubRunnerRule implements the StubFinder it allows you to find the started stubs: +package org.springframework.cloud.contract.stubrunner; + +import java.net.URL; +import java.util.Collection; +import java.util.Map; + +import org.springframework.cloud.contract.spec.Contract; + +public interface StubFinder extends StubTrigger { + /** + * For the given groupId and artifactId tries to find the matching + * URL of the running stub. + * + * @param groupId - might be null. In that case a search only via artifactId takes place + * @return URL of a running stub or throws exception if not found + */ + URL findStubUrl(String groupId, String artifactId) throws StubNotFoundException; + + /** + * For the given Ivy notation {@code [groupId]:artifactId:[version]:[classifier]} tries to + * find the matching URL of the running stub. You can also pass only {@code artifactId}. + * + * @param ivyNotation - Ivy representation of the Maven artifact + * @return URL of a running stub or throws exception if not found + */ + URL findStubUrl(String ivyNotation) throws StubNotFoundException; + + /** + * Returns all running stubs + */ + RunningStubs findAllRunningStubs(); + + /** + * Returns the list of Contracts + */ + Map<StubConfiguration, Collection<Contract>> getContracts(); +} +Example of usage in Spock tests: +@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule() + .repoRoot(StubRunnerRuleSpec.getResource("/m2repo/repository").toURI().toString()) + .downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance") + .downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer") + .withMappingsOutputFolder("target/outputmappingsforrule") + + +def 'should start WireMock servers'() { + expect: 'WireMocks are running' + rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null + rule.findStubUrl('loanIssuance') != null + rule.findStubUrl('loanIssuance') == rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') + rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null + and: + rule.findAllRunningStubs().isPresent('loanIssuance') + rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer') + rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') + and: 'Stubs were registered' + "${rule.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance' + "${rule.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer' +} + +def 'should output mappings to output folder'() { + when: + def url = rule.findStubUrl('fraudDetectionServer') + then: + new File("target/outputmappingsforrule", "fraudDetectionServer_${url.port}").exists() +} +Example of usage in JUnit tests: +@Test +public void should_start_wiremock_servers() throws Exception { + // expect: 'WireMocks are running' + then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")).isNotNull(); + then(rule.findStubUrl("loanIssuance")).isNotNull(); + then(rule.findStubUrl("loanIssuance")).isEqualTo(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")); + then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isNotNull(); + // and: + then(rule.findAllRunningStubs().isPresent("loanIssuance")).isTrue(); + then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs", "fraudDetectionServer")).isTrue(); + then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isTrue(); + // and: 'Stubs were registered' + then(httpGet(rule.findStubUrl("loanIssuance").toString() + "/name")).isEqualTo("loanIssuance"); + then(httpGet(rule.findStubUrl("fraudDetectionServer").toString() + "/name")).isEqualTo("fraudDetectionServer"); +} +Check the Common properties for JUnit and Spring for more information on how to apply global configuration of Stub Runner. + +To use the JUnit rule together with messaging you have to provide an implementation of the +MessageVerifier interface to the rule builder (e.g. rule.messageVerifier(new MyMessageVerifier())). +If you don’t do this then whenever you try to send a message an exception will be thrown. + +
+Maven settings +The stub downloader honors Maven settings for a different local repository folder. +Authentication details for repositories and profiles are currently not taken into account, so you need to specify it using the properties mentioned above. +
+
+Providing fixed ports +You can also run your stubs on fixed ports. You can do it in two different ways. One is to pass it in the properties, and the other via fluent API of +JUnit rule. +
+
+Fluent API +When using the StubRunnerRule you can add a stub to download and then pass the port for the last downloaded stub. +@ClassRule public static StubRunnerRule rule = new StubRunnerRule() + .repoRoot(repoRoot()) + .downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance") + .withPort(12345) + .downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer:12346"); +You can see that for this example the following test is valid: +then(rule.findStubUrl("loanIssuance")).isEqualTo(URI.create("http://localhost:12345").toURL()); +then(rule.findStubUrl("fraudDetectionServer")).isEqualTo(URI.create("http://localhost:12346").toURL()); +
+
+Stub Runner with Spring +Sets up Spring configuration of the Stub Runner project. +By providing a list of stubs inside your configuration file the Stub Runner automatically downloads +and registers in WireMock the selected stubs. +If you want to find the URL of your stubbed dependency you can autowire the StubFinder interface and use +its methods as presented below: +@ContextConfiguration(classes = Config, loader = SpringBootContextLoader) +@SpringBootTest(properties = [" stubrunner.cloud.enabled=false", + "stubrunner.camel.enabled=false", + 'foo=${stubrunner.runningstubs.fraudDetectionServer.port}']) +@AutoConfigureStubRunner(mappingsOutputFolder = "target/outputmappings/") +@ActiveProfiles("test") +class StubRunnerConfigurationSpec extends Specification { + + @Autowired StubFinder stubFinder + @Autowired Environment environment + @Value('${foo}') Integer foo + + @BeforeClass + @AfterClass + void setupProps() { + System.clearProperty("stubrunner.repository.root") + System.clearProperty("stubrunner.classifier") + } + + def 'should start WireMock servers'() { + expect: 'WireMocks are running' + stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null + stubFinder.findStubUrl('loanIssuance') != null + stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') + stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance') + stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs') + stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null + and: + stubFinder.findAllRunningStubs().isPresent('loanIssuance') + stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer') + stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') + and: 'Stubs were registered' + "${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance' + "${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer' + } + + def 'should throw an exception when stub is not found'() { + when: + stubFinder.findStubUrl('nonExistingService') + then: + thrown(StubNotFoundException) + when: + stubFinder.findStubUrl('nonExistingGroupId', 'nonExistingArtifactId') + then: + thrown(StubNotFoundException) + } + + def 'should register started servers as environment variables'() { + expect: + environment.getProperty("stubrunner.runningstubs.loanIssuance.port") != null + stubFinder.findAllRunningStubs().getPort("loanIssuance") == (environment.getProperty("stubrunner.runningstubs.loanIssuance.port") as Integer) + and: + environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") != null + stubFinder.findAllRunningStubs().getPort("fraudDetectionServer") == (environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") as Integer) + } + + def 'should be able to interpolate a running stub in the passed test property'() { + given: + int fraudPort = stubFinder.findAllRunningStubs().getPort("fraudDetectionServer") + expect: + fraudPort > 0 + environment.getProperty("foo", Integer) == fraudPort + foo == fraudPort + } + + def 'should dump all mappings to a file'() { + when: + def url = stubFinder.findStubUrl("fraudDetectionServer") + then: + new File("target/outputmappings/", "fraudDetectionServer_${url.port}").exists() + } + + @Configuration + @EnableAutoConfiguration + static class Config {} +} +for the following configuration file: +stubrunner: + repositoryRoot: classpath:m2repo/repository/ + ids: + - org.springframework.cloud.contract.verifier.stubs:loanIssuance + - org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer + - org.springframework.cloud.contract.verifier.stubs:bootService +Instead of using the properties you can also use the properties inside the @AutoConfigureStubRunner. +Below you can find an example of achieving the same result by setting values on the annotation. +@AutoConfigureStubRunner( + ids = ["org.springframework.cloud.contract.verifier.stubs:loanIssuance", + "org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer", + "org.springframework.cloud.contract.verifier.stubs:bootService"], + repositoryRoot = "classpath:m2repo/repository/") +Stub Runner Spring registers environment variables in the following manner +for every registered WireMock server. Example for Stub Runner ids + com.example:foo, com.example:bar. + + +stubrunner.runningstubs.foo.port + + +stubrunner.runningstubs.bar.port + + +Which you can reference in your code. +
+
+
+Stub Runner Spring Cloud +Stub Runner can integrate with Spring Cloud. +For real life examples you can check the + + +producer app sample + + +consumer app sample + + +
+Stubbing Service Discovery +The most important feature of Stub Runner Spring Cloud is the fact that it’s stubbing + + +DiscoveryClient + + +Ribbon ServerList + + +that means that regardless of the fact whether you’re using Zookeeper, Consul, Eureka or anything else, you don’t need that in your tests. +We’re starting WireMock instances of your dependencies and we’re telling your application whenever you’re using Feign, load balanced RestTemplate +or DiscoveryClient directly, to call those stubbed servers instead of calling the real Service Discovery tool. +For example this test will pass +def 'should make service discovery work'() { + expect: 'WireMocks are running' + "${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance' + "${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer' + and: 'Stubs can be reached via load service discovery' + restTemplate.getForObject('http://loanIssuance/name', String) == 'loanIssuance' + restTemplate.getForObject('http://someNameThatShouldMapFraudDetectionServer/name', String) == 'fraudDetectionServer' +} +for the following configuration file +stubrunner: + idsToServiceIds: + ivyNotation: someValueInsideYourCode + fraudDetectionServer: someNameThatShouldMapFraudDetectionServer +
+Test profiles and service discovery +In your integration tests you typically don’t want to call neither a discovery service (e.g. Eureka) +or Config Server. That’s why you create an additional test configuration in which you want to disable +these features. +Due to certain limitations of spring-cloud-commons to achieve this you have disable these properties +via a static block like presented below (example for Eureka) + //Hack to work around https://github.com/spring-cloud/spring-cloud-commons/issues/156 + static { + System.setProperty("eureka.client.enabled", "false"); + System.setProperty("spring.cloud.config.failFast", "false"); + } +
+
+
+Additional Configuration +You can match the artifactId of the stub with the name of your app by using the stubrunner.idsToServiceIds: map. +You can disable Stub Runner Ribbon support by providing: stubrunner.cloud.ribbon.enabled equal to false +You can disable Stub Runner support by providing: stubrunner.cloud.enabled equal to false + +By default all service discovery will be stubbed. That means that regardless of the fact if you have +an existing DiscoveryClient its results will be ignored. However, if you want to reuse it, just set + stubrunner.cloud.delegate.enabled to true and then your existing DiscoveryClient results will be + merged with the stubbed ones. + +The default Maven configuration used by Stub Runner can be tweaked either +via the following system properties or environment variables + + +maven.repo.local - path to the custom maven local repository location + + +org.apache.maven.user-settings - path to custom maven user settings location + + +org.apache.maven.global-settings - path to maven global settings location + + +
+
+
+Stub Runner Boot Application +Spring Cloud Contract Stub Runner Boot is a Spring Boot application that exposes REST endpoints to +trigger the messaging labels and to access started WireMock servers. +One of the use-cases is to run some smoke (end to end) tests on a deployed application. +You can check out the Spring Cloud Pipelines +project for more information. +
+How to use it? +
+Stub Runner Server +Just add the +compile "org.springframework.cloud:spring-cloud-starter-stub-runner" +Annotate a class with @EnableStubRunnerServer, build a fat-jar and you’re ready to go! +For the properties check the Stub Runner Spring section. +
+
+Stub Runner Server Fat Jar +You can download a standalone JAR from Maven (for example, for version 1.2.3.RELEASE), as follows: +$ wget -O stub-runner.jar 'https://search.maven.org/remote_content?g=org.springframework.cloud&a=spring-cloud-contract-stub-runner-boot&v=1.2.3.RELEASE' +$ java -jar stub-runner.jar --stubrunner.ids=... --stubrunner.repositoryRoot=... +
+
+Spring Cloud CLI +Starting from 1.4.0.RELEASE version of the Spring Cloud CLI +project you can start Stub Runner Boot by executing spring cloud stubrunner. +In order to pass the configuration just create a stubrunner.yml file in the current working directory +or a subdirectory called config or in ~/.spring-cloud. The file could look like this +(example for running stubs installed locally) + +stubrunner.yml + +stubrunner: + workOffline: true + ids: + - com.example:beer-api-producer:+:9876 + + +and then just call spring cloud stubrunner from your terminal window to start +the Stub Runner server. It will be available at port 8750. +
+
+
+Endpoints +
+HTTP + + +GET /stubs - returns a list of all running stubs in ivy:integer notation + + +GET /stubs/{ivy} - returns a port for the given ivy notation (when calling the endpoint ivy can also be artifactId only) + + +
+
+Messaging +For Messaging + + +GET /triggers - returns a list of all running labels in ivy : [ label1, label2 …​] notation + + +POST /triggers/{label} - executes a trigger with label + + +POST /triggers/{ivy}/{label} - executes a trigger with label for the given ivy notation (when calling the endpoint ivy can also be artifactId only) + + +
+
+
+Example +@ContextConfiguration(classes = StubRunnerBoot, loader = SpringBootContextLoader) +@SpringBootTest(properties = "spring.cloud.zookeeper.enabled=false") +@ActiveProfiles("test") +class StubRunnerBootSpec extends Specification { + + @Autowired StubRunning stubRunning + + def setup() { + RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), + new TriggerController(stubRunning)) + } + + def 'should return a list of running stub servers in "full ivy:port" notation'() { + when: + String response = RestAssuredMockMvc.get('/stubs').body.asString() + then: + def root = new JsonSlurper().parseText(response) + root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs' instanceof Integer + } + + def 'should return a port on which a [#stubId] stub is running'() { + when: + def response = RestAssuredMockMvc.get("/stubs/${stubId}") + then: + response.statusCode == 200 + response.body.as(Integer) > 0 + where: + stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:+:stubs', + 'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs', + 'org.springframework.cloud.contract.verifier.stubs:bootService:+', + 'org.springframework.cloud.contract.verifier.stubs:bootService', + 'bootService'] + } + + def 'should return 404 when missing stub was called'() { + when: + def response = RestAssuredMockMvc.get("/stubs/a:b:c:d") + then: + response.statusCode == 404 + } + + def 'should return a list of messaging labels that can be triggered when version and classifier are passed'() { + when: + String response = RestAssuredMockMvc.get('/triggers').body.asString() + then: + def root = new JsonSlurper().parseText(response) + root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs'?.containsAll(["delete_book","return_book_1","return_book_2"]) + } + + def 'should trigger a messaging label'() { + given: + StubRunning stubRunning = Mock() + RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning)) + when: + def response = RestAssuredMockMvc.post("/triggers/delete_book") + then: + response.statusCode == 200 + and: + 1 * stubRunning.trigger('delete_book') + } + + def 'should trigger a messaging label for a stub with [#stubId] ivy notation'() { + given: + StubRunning stubRunning = Mock() + RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning)) + when: + def response = RestAssuredMockMvc.post("/triggers/$stubId/delete_book") + then: + response.statusCode == 200 + and: + 1 * stubRunning.trigger(stubId, 'delete_book') + where: + stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:stubs', 'org.springframework.cloud.contract.verifier.stubs:bootService', 'bootService'] + } + + def 'should throw exception when trigger is missing'() { + when: + RestAssuredMockMvc.post("/triggers/missing_label") + then: + Exception e = thrown(Exception) + e.message.contains("Exception occurred while trying to return [missing_label] label.") + e.message.contains("Available labels are") + e.message.contains("org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs=[]") + e.message.contains("org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs=") + } + +} +
+
+Stub Runner Boot with Service Discovery +One of the possibilities of using Stub Runner Boot is to use it as a feed of stubs for "smoke-tests". What does it mean? + Let’s assume that you don’t want to deploy 50 microservice to a test environment in order + to check if your application is working fine. You’ve already executed a suite of tests during the build process + but you would also like to ensure that the packaging of your application is fine. What you can do + is to deploy your application to an environment, start it and run a couple of tests on it to see if + it’s working fine. We can call those tests smoke-tests since their idea is to check only a handful + of testing scenarios. +The problem with this approach is such that if you’re doing microservices most likely you’re + using a service discovery tool. Stub Runner Boot allows you to solve this issue by starting the + required stubs and register them in a service discovery tool. Let’s take a look at an example of + such a setup with Eureka. Let’s assume that Eureka was already running. +@SpringBootApplication +@EnableStubRunnerServer +@EnableEurekaClient +@AutoConfigureStubRunner +public class StubRunnerBootEurekaExample { + + public static void main(String[] args) { + SpringApplication.run(StubRunnerBootEurekaExample.class, args); + } + +} +As you can see we want to start a Stub Runner Boot server @EnableStubRunnerServer, enable Eureka client @EnableEurekaClient +and we want to have the stub runner feature turned on @AutoConfigureStubRunner. +Now let’s assume that we want to start this application so that the stubs get automatically registered. + We can do it by running the app java -jar ${SYSTEM_PROPS} stub-runner-boot-eureka-example.jar where + ${SYSTEM_PROPS} would contain the following list of properties +-Dstubrunner.repositoryRoot=https://repo.spring.io/snapshot (1) +-Dstubrunner.cloud.stubbed.discovery.enabled=false (2) +-Dstubrunner.ids=org.springframework.cloud.contract.verifier.stubs:loanIssuance,org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer,org.springframework.cloud.contract.verifier.stubs:bootService (3) +-Dstubrunner.idsToServiceIds.fraudDetectionServer=someNameThatShouldMapFraudDetectionServer (4) + +(1) - we tell Stub Runner where all the stubs reside +(2) - we don't want the default behaviour where the discovery service is stubbed. That's why the stub registration will be picked +(3) - we provide a list of stubs to download +(4) - we provide a list of artifactId to serviceId mapping +That way your deployed application can send requests to started WireMock servers via the service +discovery. Most likely points 1-3 could be set by default in application.yml cause they are not +likely to change. That way you can provide only the list of stubs to download whenever you start +the Stub Runner Boot. +
+
+
+Stubs Per Consumer +There are cases in which 2 consumers of the same endpoint want to have 2 different responses. + +This approach also allows you to immediately know which consumer is using which part of your API. +You can remove part of a response that your API produces and you can see which of your autogenerated tests +fails. If none fails then you can safely delete that part of the response cause nobody is using it. + +Let’s look at the following example for contract defined for the producer called producer. +There are 2 consumers: foo-consumer and bar-consumer. +Consumer foo-service +request { + url '/foo' + method GET() +} +response { + status 200 + body( + foo: "foo" + } +} +Consumer bar-service +request { + url '/foo' + method GET() +} +response { + status 200 + body( + bar: "bar" + } +} +You can’t produce for the same request 2 different responses. That’s why you can properly package the +contracts and then profit from the stubsPerConsumer feature. +On the producer side the consumers can have a folder that contains contracts related only to them. +By setting the stubrunner.stubs-per-consumer flag to true we no longer register all stubs but only those that +correspond to the consumer application’s name. In other words we’ll scan the path of every stub and +if it contains the subfolder with name of the consumer in the path only then will it get registered. +On the foo producer side the contracts would look like this +. +└── contracts + ├── bar-consumer + │   ├── bookReturnedForBar.groovy + │   └── shouldCallBar.groovy + └── foo-consumer + ├── bookReturnedForFoo.groovy + └── shouldCallFoo.groovy +Being the bar-consumer consumer you can either set the spring.application.name or the stubrunner.consumer-name to bar-consumer +Or set the test as follows: +@ContextConfiguration(classes = Config, loader = SpringBootContextLoader) +@SpringBootTest(properties = ["spring.application.name=bar-consumer"]) +@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers", + repositoryRoot = "classpath:m2repo/repository/", + stubsPerConsumer = true) +class StubRunnerStubsPerConsumerSpec extends Specification { +... +} +Then only the stubs registered under a path that contains the bar-consumer in its name (i.e. those from the +src/test/resources/contracts/bar-consumer/some/contracts/…​ folder) will be allowed to be referenced. +Or set the consumer name explicitly +@ContextConfiguration(classes = Config, loader = SpringBootContextLoader) +@SpringBootTest +@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers", + repositoryRoot = "classpath:m2repo/repository/", + consumerName = "foo-consumer", + stubsPerConsumer = true) +class StubRunnerStubsPerConsumerWithConsumerNameSpec extends Specification { +... +} +Then only the stubs registered under a path that contains the foo-consumer in its name (i.e. those from the +src/test/resources/contracts/foo-consumer/some/contracts/…​ folder) will be allowed to be referenced. +You can check out issue 224 for more +information about the reasons behind this change. +
+
+Common +This section briefly describes common properties, including: + + + + + + + + +
+Common Properties for JUnit and Spring +You can set repetitive properties by using system properties or Spring configuration +properties. Here are their names with their default values: + + + + + + + +Property name +Default value +Description + + + + +stubrunner.minPort +10000 +Minimum value of a port for a started WireMock with stubs. + + +stubrunner.maxPort +15000 +Maximum value of a port for a started WireMock with stubs. + + +stubrunner.repositoryRoot + +Maven repo URL. If blank, then call the local maven repo. + + +stubrunner.classifier +stubs +Default classifier for the stub artifacts. + + +stubrunner.workOffline +false +If true, then do not contact any remote repositories to +download stubs. + + +stubrunner.ids + +Array of Ivy notation stubs to download. + + +stubrunner.username + +Optional username to access the tool that stores the JARs with +stubs. + + +stubrunner.password + +Optional password to access the tool that stores the JARs with +stubs. + + +stubrunner.stubsPerConsumer +false +Set to true if you want to use different stubs for +each consumer instead of registering all stubs for every consumer. + + +stubrunner.consumerName + +If you want to use a stub for each consumer and want to +override the consumer name just change this value. + + + + +
+
+Stub Runner Stubs IDs +You can provide the stubs to download via the stubrunner.ids system property. They +follow this pattern: +groupId:artifactId:version:classifier:port +Note that version, classifier and port are optional. + + +If you do not provide the port, a random one will be picked. + + +If you do not provide the classifier, the default is used. (Note that you can +pass an empty classifier this way: groupId:artifactId:version:). + + +If you do not provide the version, then the + will be passed and the latest one is +downloaded. + + +port means the port of the WireMock server. + +Starting with version 1.0.4, you can provide a range of versions that you +would like the Stub Runner to take into consideration. You can read more about the +Aether versioning +ranges here. + +
+
+
+Stub Runner Docker +We’re publishing a spring-cloud/spring-cloud-contract-stub-runner Docker image +that will start the standalone version of Stub Runner. +If you want to learn more about the basics of Maven, artifact ids, +group ids, classifiers and Artifact Managers, just click here . +
+How to use it +Just execute the docker image. You can pass any of the +as environment variables. The convention is that all the +letters should be upper case. The camel case notation should +and the dot (.) should be separated via underscore (_). E.g. + the stubrunner.repositoryRoot property should be represented + as a STUBRUNNER_REPOSITORY_ROOT environment variable. +
+
+Example of client side usage in a non JVM project +We’d like to use the stubs created in this step. +Let’s assume that we want to run the stubs on port 9876. The NodeJS code +is available here: +$ git clone https://github.com/spring-cloud-samples/spring-cloud-contract-nodejs +$ cd bookstore +Let’s run the Stub Runner Boot application with the stubs. +# Provide the Spring Cloud Contract Docker version +$ SC_CONTRACT_DOCKER_VERSION="..." +# The IP at which the app is running and Docker container can reach it +$ APP_IP="192.168.0.100" +# Spring Cloud Contract Stub Runner properties +$ STUBRUNNER_PORT="8083" +# Stub coordinates 'groupId:artifactId:version:classifier:port' +$ STUBRUNNER_IDS="com.example:bookstore:0.0.1.RELEASE:stubs:9876" +$ STUBRUNNER_REPOSITORY_ROOT="http://${APP_IP}:8081/artifactory/libs-release-local" +# Run the docker with Stub Runner Boot +$ docker run --rm -e "STUBRUNNER_IDS=${STUBRUNNER_IDS}" -e "STUBRUNNER_REPOSITORY_ROOT=${STUBRUNNER_REPOSITORY_ROOT}" -p "${STUBRUNNER_PORT}:${STUBRUNNER_PORT}" -p "9876:9876" springcloud/spring-cloud-contract-stub-runner:"${SC_CONTRACT_DOCKER_VERSION}" +What’s happening is that + + +a standalone Stub Runner application got started + + +it downloaded the stub with coordinates com.example:bookstore:0.0.1.RELEASE:stubs on port 9876 + + +it got downloaded from Artifactory running at http://192.168.0.100:8081/artifactory/libs-release-local + + +after a while Stub Runner will be running on port 8083 + + +and the stubs will be running at port 9876 + + +On the server side we built a stateful stub. Let’s use curl to assert +that the stubs are setup properly. +# let's execute the first request (no response is returned) +$ curl -H "Content-Type:application/json" -X POST --data '{ "title" : "Title", "genre" : "Genre", "description" : "Description", "author" : "Author", "publisher" : "Publisher", "pages" : 100, "image_url" : "https://d213dhlpdb53mu.cloudfront.net/assets/pivotal-square-logo-41418bd391196c3022f3cd9f3959b3f6d7764c47873d858583384e759c7db435.svg", "buy_url" : "https://pivotal.io" }' http://localhost:9876/api/books +# Now time for the second request +$ curl -X GET http://localhost:9876/api/books +# You will receive contents of the JSON +
+
+ + +Stub Runner for Messaging +Stub Runner can run the published stubs in memory. It can integrate with the following +frameworks: + + +Spring Integration + + +Spring Cloud Stream + + +Apache Camel + + +Spring AMQP + + +It also provides entry points to integrate with any other solution on the market. + +If you have multiple frameworks on the classpath Stub Runner will need to +define which one should be used. Let’s assume that you have both AMQP, Spring Cloud Stream and Spring Integration +on the classpath. Then you need to set stubrunner.stream.enabled=false and stubrunner.integration.enabled=false. +That way the only remaining framework is Spring AMQP. + +
+Stub triggering +To trigger a message, use the StubTrigger interface: +package org.springframework.cloud.contract.stubrunner; + +import java.util.Collection; +import java.util.Map; + +public interface StubTrigger { + + /** + * Triggers an event by a given label for a given {@code groupid:artifactid} notation. You can use only {@code artifactId} too. + * + * Feature related to messaging. + * + * @return true - if managed to run a trigger + */ + boolean trigger(String ivyNotation, String labelName); + + /** + * Triggers an event by a given label. + * + * Feature related to messaging. + * + * @return true - if managed to run a trigger + */ + boolean trigger(String labelName); + + /** + * Triggers all possible events. + * + * Feature related to messaging. + * + * @return true - if managed to run a trigger + */ + boolean trigger(); + + /** + * Returns a mapping of ivy notation of a dependency to all the labels it has. + * + * Feature related to messaging. + */ + Map<String, Collection<String>> labels(); +} +For convenience, the StubFinder interface extends StubTrigger, so you only need one +or the other in your tests. +StubTrigger gives you the following options to trigger a message: + + + + + + + + + + + + + + +
+Trigger by Label +stubFinder.trigger('return_book_1') +
+
+Trigger by Group and Artifact Ids +stubFinder.trigger('org.springframework.cloud.contract.verifier.stubs:camelService', 'return_book_1') +
+
+Trigger by Artifact Ids +stubFinder.trigger('camelService', 'return_book_1') +
+
+Trigger All Messages +stubFinder.trigger() +
+
+
+Stub Runner Camel +Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Apache Camel. For the provided artifacts, it automatically downloads the +stubs and registers the required routes. +
+Adding the Runner to the Project +You can have both Apache Camel and Spring Cloud Contract Stub Runner on the classpath. +Remember to annotate your test class with @AutoConfigureStubRunner. +
+
+Disabling the functionality +If you need to disable this functionality, set the stubrunner.camel.enabled=false +property. +Assume that you have the following Maven repository with deployed stubs for the +camelService application: +└── .m2 + └── repository + └── io + └── codearte + └── accurest + └── stubs + └── camelService + ├── 0.0.1-SNAPSHOT + │   ├── camelService-0.0.1-SNAPSHOT.pom + │   ├── camelService-0.0.1-SNAPSHOT-stubs.jar + │   └── maven-metadata-local.xml + └── maven-metadata-local.xml +Further assume that the stubs contain the following structure: +├── META-INF +│   └── MANIFEST.MF +└── repository + ├── accurest + │   ├── bookDeleted.groovy + │   ├── bookReturned1.groovy + │   └── bookReturned2.groovy + └── mappings +Consider the following contracts (numbered 1): +Contract.make { + label 'return_book_1' + input { + triggeredBy('bookReturnedTriggered()') + } + outputMessage { + sentTo('jms:output') + body('''{ "bookName" : "foo" }''') + headers { + header('BOOK-NAME', 'foo') + } + } +} +Now consider 2 +Contract.make { + label 'return_book_2' + input { + messageFrom('jms:input') + messageBody([ + bookName: 'foo' + ]) + messageHeaders { + header('sample', 'header') + } + } + outputMessage { + sentTo('jms:output') + body([ + bookName: 'foo' + ]) + headers { + header('BOOK-NAME', 'foo') + } + } +} +These examples lend themselves to three scenarios: + + + + + + + + + + + +
+Scenario 1 (no input message) +To trigger a message via the return_book_1 label, use the StubTigger interface, as +follows: +stubFinder.trigger('return_book_1') +To listen to the output of the message sent to jms:output: +Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000) +The received message passes the following assertions: +receivedMessage != null +assertThatBodyContainsBookNameFoo(receivedMessage.in.body) +receivedMessage.in.headers.get('BOOK-NAME') == 'foo' +
+
+Scenario 2 (output triggered by input) +Since the route is set for you, you can send a message to the jms:output +destination: +camelContext.createProducerTemplate().sendBodyAndHeaders('jms:input', new BookReturned('foo'), [sample: 'header']) +You can listen to the output of the message sent to jms:output: +Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000) +The received message passes the following assertions: +receivedMessage != null +assertThatBodyContainsBookNameFoo(receivedMessage.in.body) +receivedMessage.in.headers.get('BOOK-NAME') == 'foo' +
+
+Scenario 3 (input with no output) +Since the route is set for you, you can send a message to the jms:output +destination: +camelContext.createProducerTemplate().sendBodyAndHeaders('jms:delete', new BookReturned('foo'), [sample: 'header']) +
+
+
+
+Stub Runner Integration +Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Spring Integration. For the provided artifacts, it automatically downloads +the stubs and registers the required routes. +
+Adding the Runner to the Project +You can have both Spring Integration and Spring Cloud Contract Stub Runner on the +classpath. Remember to annotate your test class with @AutoConfigureStubRunner. +
+
+Disabling the functionality +If you need to disable this functionality, set the +stubrunner.integration.enabled=false property. +Assume that you have the following Maven repository with deployed stubs for the +integrationService application: +└── .m2 + └── repository + └── io + └── codearte + └── accurest + └── stubs + └── integrationService + ├── 0.0.1-SNAPSHOT + │   ├── integrationService-0.0.1-SNAPSHOT.pom + │   ├── integrationService-0.0.1-SNAPSHOT-stubs.jar + │   └── maven-metadata-local.xml + └── maven-metadata-local.xml +Further assume the stubs contain the following structure: +├── META-INF +│   └── MANIFEST.MF +└── repository + ├── accurest + │   ├── bookDeleted.groovy + │   ├── bookReturned1.groovy + │   └── bookReturned2.groovy + └── mappings +Consider the following contracts (numbered 1): +Contract.make { + label 'return_book_1' + input { + triggeredBy('bookReturnedTriggered()') + } + outputMessage { + sentTo('output') + body('''{ "bookName" : "foo" }''') + headers { + header('BOOK-NAME', 'foo') + } + } +} +Now consider 2: +Contract.make { + label 'return_book_2' + input { + messageFrom('input') + messageBody([ + bookName: 'foo' + ]) + messageHeaders { + header('sample', 'header') + } + } + outputMessage { + sentTo('output') + body([ + bookName: 'foo' + ]) + headers { + header('BOOK-NAME', 'foo') + } + } +} +and the following Spring Integration Route: +<?xml version="1.0" encoding="UTF-8"?> +<beans:beans xmlns="http://www.springframework.org/schema/integration" + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xmlns:beans="http://www.springframework.org/schema/beans" + xsi:schemaLocation="http://www.springframework.org/schema/beans + https://www.springframework.org/schema/beans/spring-beans.xsd + http://www.springframework.org/schema/integration + https://www.springframework.org/schema/integration/spring-integration.xsd"> + + + <!-- REQUIRED FOR TESTING --> + <bridge input-channel="output" + output-channel="outputTest"/> + + <channel id="outputTest"> + <queue/> + </channel> + +</beans:beans> +These examples lend themselves to three scenarios: + + + + + + + + + + + +
+Scenario 1 (no input message) +To trigger a message via the return_book_1 label, use the StubTigger interface, as +follows: +stubFinder.trigger('return_book_1') +To listen to the output of the message sent to output: +Message<?> receivedMessage = messaging.receive('outputTest') +The received message would pass the following assertions: +receivedMessage != null +assertJsons(receivedMessage.payload) +receivedMessage.headers.get('BOOK-NAME') == 'foo' +
+
+Scenario 2 (output triggered by input) +Since the route is set for you, you can send a message to the output +destination: +messaging.send(new BookReturned('foo'), [sample: 'header'], 'input') +To listen to the output of the message sent to output: +Message<?> receivedMessage = messaging.receive('outputTest') +The received message passes the following assertions: +receivedMessage != null +assertJsons(receivedMessage.payload) +receivedMessage.headers.get('BOOK-NAME') == 'foo' +
+
+Scenario 3 (input with no output) +Since the route is set for you, you can send a message to the input destination: +messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete') +
+
+
+
+Stub Runner Stream +Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to +integrate with Spring Stream. For the provided artifacts, it automatically downloads the +stubs and registers the required routes. + +If Stub Runner’s integration with Stream the messageFrom or sentTo Strings +are resolved first as a destination of a channel and no such destination exists, the +destination is resolved as a channel name. + + +If you want to use Spring Cloud Stream remember, to add a dependency on +org.springframework.cloud:spring-cloud-stream-test-support. + + +Maven + +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-stream-test-support</artifactId> + <scope>test</scope> +</dependency> + + + +Gradle + +testCompile "org.springframework.cloud:spring-cloud-stream-test-support" + + +
+Adding the Runner to the Project +You can have both Spring Cloud Stream and Spring Cloud Contract Stub Runner on the +classpath. Remember to annotate your test class with @AutoConfigureStubRunner. +
+
+Disabling the functionality +If you need to disable this functionality, set the stubrunner.stream.enabled=false +property. +Assume that you have the following Maven repository with a deployed stubs for the +streamService application: +└── .m2 + └── repository + └── io + └── codearte + └── accurest + └── stubs + └── streamService + ├── 0.0.1-SNAPSHOT + │   ├── streamService-0.0.1-SNAPSHOT.pom + │   ├── streamService-0.0.1-SNAPSHOT-stubs.jar + │   └── maven-metadata-local.xml + └── maven-metadata-local.xml +Further assume the stubs contain the following structure: +├── META-INF +│   └── MANIFEST.MF +└── repository + ├── accurest + │   ├── bookDeleted.groovy + │   ├── bookReturned1.groovy + │   └── bookReturned2.groovy + └── mappings +Consider the following contracts (numbered 1): +Contract.make { + label 'return_book_1' + input { triggeredBy('bookReturnedTriggered()') } + outputMessage { + sentTo('returnBook') + body('''{ "bookName" : "foo" }''') + headers { header('BOOK-NAME', 'foo') } + } +} +Now consider 2: +Contract.make { + label 'return_book_2' + input { + messageFrom('bookStorage') + messageBody([ + bookName: 'foo' + ]) + messageHeaders { header('sample', 'header') } + } + outputMessage { + sentTo('returnBook') + body([ + bookName: 'foo' + ]) + headers { header('BOOK-NAME', 'foo') } + } +} +Now consider the following Spring configuration: +stubrunner.repositoryRoot: classpath:m2repo/repository/ +stubrunner.ids: org.springframework.cloud.contract.verifier.stubs:streamService:0.0.1-SNAPSHOT:stubs + +spring: + cloud: + stream: + bindings: + output: + destination: returnBook + input: + destination: bookStorage + +server: + port: 0 + +debug: true +These examples lend themselves to three scenarios: + + + + + + + + + + + +
+Scenario 1 (no input message) +To trigger a message via the return_book_1 label, use the StubTrigger interface as +follows: +stubFinder.trigger('return_book_1') +To listen to the output of the message sent to a channel whose destination is +returnBook: +Message<?> receivedMessage = messaging.receive('returnBook') +The received message passes the following assertions: +receivedMessage != null +assertJsons(receivedMessage.payload) +receivedMessage.headers.get('BOOK-NAME') == 'foo' +
+
+Scenario 2 (output triggered by input) +Since the route is set for you, you can send a message to the bookStorage +destination: +messaging.send(new BookReturned('foo'), [sample: 'header'], 'bookStorage') +To listen to the output of the message sent to returnBook: +Message<?> receivedMessage = messaging.receive('returnBook') +The received message passes the following assertions: +receivedMessage != null +assertJsons(receivedMessage.payload) +receivedMessage.headers.get('BOOK-NAME') == 'foo' +
+
+Scenario 3 (input with no output) +Since the route is set for you, you can send a message to the output +destination: +messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete') +
+
+
+
+Stub Runner Spring AMQP +Spring Cloud Contract Verifier Stub Runner’s messaging module provides an easy way to +integrate with Spring AMQP’s Rabbit Template. For the provided artifacts, it +automatically downloads the stubs and registers the required routes. +The integration tries to work standalone (that is, without interaction with a running +RabbitMQ message broker). It expects a RabbitTemplate on the application context and +uses it as a spring boot test named @SpyBean. As a result, it can use the mockito spy +functionality to verify and inspect messages sent by the application. +On the message consumer side, the stub runner considers all @RabbitListener annotated +endpoints and all SimpleMessageListenerContainer objects on the application context. +As messages are usually sent to exchanges in AMQP, the message contract contains the +exchange name as the destination. Message listeners on the other side are bound to +queues. Bindings connect an exchange to a queue. If message contracts are triggered, the +Spring AMQP stub runner integration looks for bindings on the application context that +match this exchange. Then it collects the queues from the Spring exchanges and tries to +find message listeners bound to these queues. The message is triggered for all matching +message listeners. +
+Adding the Runner to the Project +You can have both Spring AMQP and Spring Cloud Contract Stub Runner on the classpath and +set the property stubrunner.amqp.enabled=true. Remember to annotate your test class +with @AutoConfigureStubRunner. + +If you already have Stream and Integration on the classpath, you need +to disable them explicitly by setting the stubrunner.stream.enabled=false and +stubrunner.integration.enabled=false properties. + +Assume that you have the following Maven repository with a deployed stubs for the +spring-cloud-contract-amqp-test application. +└── .m2 + └── repository + └── com + └── example + └── spring-cloud-contract-amqp-test + ├── 0.4.0-SNAPSHOT + │   ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT.pom + │   ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT-stubs.jar + │   └── maven-metadata-local.xml + └── maven-metadata-local.xml +Further assume that the stubs contain the following structure: +├── META-INF +│   └── MANIFEST.MF +└── contracts + └── shouldProduceValidPersonData.groovy +Consider the following contract: +Contract.make { + // Human readable description + description 'Should produce valid person data' + // Label by means of which the output message can be triggered + label 'contract-test.person.created.event' + // input to the contract + input { + // the contract will be triggered by a method + triggeredBy('createPerson()') + } + // output message of the contract + outputMessage { + // destination to which the output message will be sent + sentTo 'contract-test.exchange' + headers { + header('contentType': 'application/json') + header('__TypeId__': 'org.springframework.cloud.contract.stubrunner.messaging.amqp.Person') + } + // the body of the output message + body ([ + id: $(consumer(9), producer(regex("[0-9]+"))), + name: "me" + ]) + } +} +Now consider the following Spring configuration: +stubrunner: + repositoryRoot: classpath:m2repo/repository/ + ids: org.springframework.cloud.contract.verifier.stubs.amqp:spring-cloud-contract-amqp-test:0.4.0-SNAPSHOT:stubs + amqp: + enabled: true +server: + port: 0 +
+Triggering the message +To trigger a message using the contract above, use the StubTrigger interface as +follows: +stubTrigger.trigger("contract-test.person.created.event") +The message has a destination of contract-test.exchange, so the Spring AMQP stub runner +integration looks for bindings related to this exchange. +@Bean +public Binding binding() { + return BindingBuilder.bind(new Queue("test.queue")).to(new DirectExchange("contract-test.exchange")).with("#"); +} +The binding definition binds the queue test.queue. As a result, the following listener +definition is matched and invoked with the contract message. +@Bean +public SimpleMessageListenerContainer simpleMessageListenerContainer(ConnectionFactory connectionFactory, + MessageListenerAdapter listenerAdapter) { + SimpleMessageListenerContainer container = new SimpleMessageListenerContainer(); + container.setConnectionFactory(connectionFactory); + container.setQueueNames("test.queue"); + container.setMessageListener(listenerAdapter); + + return container; +} +Also, the following annotated listener matches and is invoked: +@RabbitListener(bindings = @QueueBinding( + value = @Queue(value = "test.queue"), + exchange = @Exchange(value = "contract-test.exchange", ignoreDeclarationExceptions = "true"))) +public void handlePerson(Person person) { + this.person = person; +} + +The message is directly handed over to the onMessage method of the +MessageListener associated with the matching SimpleMessageListenerContainer. + +
+
+Spring AMQP Test Configuration +In order to avoid Spring AMQP trying to connect to a running broker during our tests +configure a mock ConnectionFactory. +To disable the mocked ConnectionFactory, set the following property: +stubrunner.amqp.mockConnection=false +stubrunner: + amqp: + mockConnection: false +
+
+
+ + +Contract DSL +Spring Cloud Contract supports out of the box 2 types of DSL. One written in +Groovy and one written in YAML. +If you decide to write the contract in Groovy, do not be alarmed if you have not used Groovy +before. Knowledge of the language is not really needed, as the Contract DSL uses only a +tiny subset of it (only literals, method calls and closures). Also, the DSL is statically +typed, to make it programmer-readable without any knowledge of the DSL itself. + +Remember that, inside the Groovy contract file, you have to provide the fully +qualified name to the Contract class and make static imports, such as +org.springframework.cloud.spec.Contract.make { …​ }. You can also provide an import to +the Contract class: import org.springframework.cloud.spec.Contract and then call +Contract.make { …​ }. + + +Spring Cloud Contract supports defining multiple contracts in a single file. + +The following is a complete example of a Groovy contract definition: +org.springframework.cloud.contract.spec.Contract.make { + request { + method 'PUT' + url '/api/12' + headers { + header 'Content-Type': 'application/vnd.org.springframework.cloud.contract.verifier.twitter-places-analyzer.v1+json' + } + body '''\ + [{ + "created_at": "Sat Jul 26 09:38:57 +0000 2014", + "id": 492967299297845248, + "id_str": "492967299297845248", + "text": "Gonna see you at Warsaw", + "place": + { + "attributes":{}, + "bounding_box": + { + "coordinates": + [[ + [-77.119759,38.791645], + [-76.909393,38.791645], + [-76.909393,38.995548], + [-77.119759,38.995548] + ]], + "type":"Polygon" + }, + "country":"United States", + "country_code":"US", + "full_name":"Washington, DC", + "id":"01fbe706f872cb32", + "name":"Washington", + "place_type":"city", + "url": "https://api.twitter.com/1/geo/id/01fbe706f872cb32.json" + } + }] + ''' + } + response { + status 200 + } +} +The following is a complete example of a YAML contract definition: +description: Some description +name: some name +priority: 8 +ignored: true +request: + url: /foo + queryParameters: + a: b + b: c + method: PUT + headers: + foo: bar + fooReq: baz + body: + foo: bar + matchers: + body: + - path: $.foo + type: by_regex + value: bar + headers: + - key: foo + regex: bar +response: + status: 200 + headers: + foo2: bar + foo3: foo33 + fooRes: baz + body: + foo2: bar + foo3: baz + matchers: + body: + - path: $.foo2 + type: by_regex + value: bar + - path: $.foo3 + type: by_command + value: executeMe($it) + headers: + - key: foo2 + regex: bar + - key: foo3 + command: andMeToo($it) + +You can compile contracts to stubs mapping using standalone maven command: +mvn org.springframework.cloud:spring-cloud-contract-maven-plugin:convert + +
+Limitations + +Spring Cloud Contract Verifier does not properly support XML. Please use JSON or +help us implement this feature. + + +The support for verifying the size of JSON arrays is experimental. If you want +to turn it on, please set the value of the following system property to true: +spring.cloud.contract.verifier.assert.size. By default, this feature is set to false. +You can also provide the assertJsonSize property in the plugin configuration. + + +Because JSON structure can have any form, it can be impossible to parse it +properly when using the Groovy DSL and the value(consumer(…​), producer(…​)) notation in GString. That +is why you should use the Groovy Map notation. + +
+
+Common Top-Level elements +The following sections describe the most common top-level elements: + + + + + + + + + + + + + + + + + +
+Description +You can add a description to your contract. The description is arbitrary text. The +following code shows an example: + +Groovy DSL + + org.springframework.cloud.contract.spec.Contract.make { + description(''' +given: + An input +when: + Sth happens +then: + Output +''') + } + + + +YAML + +description: Some description +name: some name +priority: 8 +ignored: true +request: + url: /foo + queryParameters: + a: b + b: c + method: PUT + headers: + foo: bar + fooReq: baz + body: + foo: bar + matchers: + body: + - path: $.foo + type: by_regex + value: bar + headers: + - key: foo + regex: bar +response: + status: 200 + headers: + foo2: bar + foo3: foo33 + fooRes: baz + body: + foo2: bar + foo3: baz + matchers: + body: + - path: $.foo2 + type: by_regex + value: bar + - path: $.foo3 + type: by_command + value: executeMe($it) + headers: + - key: foo2 + regex: bar + - key: foo3 + command: andMeToo($it) + + +
+
+Name +You can provide a name for your contract. Assume that you provided the following name: +should register a user. If you do so, the name of the autogenerated test is +validate_should_register_a_user. Also, the name of the stub in a WireMock stub is +should_register_a_user.json. + +You must ensure that the name does not contain any characters that make the +generated test not compile. Also, remember that, if you provide the same name for +multiple contracts, your autogenerated tests fail to compile and your generated stubs +override each other. + + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + name("some_special_name") +} + + + +YAML + +name: some name + + +
+
+Ignoring Contracts +If you want to ignore a contract, you can either set a value of ignored contracts in the +plugin configuration or set the ignored property on the contract itself: + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + ignored() +} + + + +YAML + +ignored: true + + +
+
+Passing Values from Files +Starting with version 1.2.0, you can pass values from files. Assume that you have the +following resources in our project. +└── src +    └── test +       └── resources +          └── contracts +    ├── readFromFile.groovy +    ├── request.json +    └── response.json +Further assume that your contract is as follows: + +Groovy DSL + +import org.springframework.cloud.contract.spec.Contract + +Contract.make { + request { + method('PUT') + headers { + contentType(applicationJson()) + } + body(file("request.json")) + url("/1") + } + response { + status 200 + body(file("response.json")) + headers { + contentType(textPlain()) + } + } +} + + + +YAML + +request: + method: GET + url: /foo + bodyFromFile: request.json +response: + status: 200 + bodyFromFile: response.json + + +Further assume that the JSON files is as follows: +request.json +{ "status" : "REQUEST" } +response.json +{ "status" : "RESPONSE" } +When test or stub generation takes place, the contents of the file is passed to the body +of a request or a response. The name of the file needs to be a file with location +relative to the folder in which the contract lays. +
+
+HTTP Top-Level Elements +The following methods can be called in the top-level closure of a contract definition. +request and response are mandatory. priority is optional. + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + // Definition of HTTP request part of the contract + // (this can be a valid request or invalid depending + // on type of contract being specified). + request { + //... + } + + // Definition of HTTP response part of the contract + // (a service implementing this contract should respond + // with following response after receiving request + // specified in "request" part above). + response { + //... + } + + // Contract priority, which can be used for overriding + // contracts (1 is highest). Priority is optional. + priority 1 +} + + + +YAML + +priority: 8 +request: +... +response: +... + + + +If you want to make your contract have a higher value of priority +you need to pass a lower number to the priority tag / method. E.g. priority with +value 5 has higher priority than priority with value 10. + +
+
+
+Request +The HTTP protocol requires only method and url to be specified in a request. The +same information is mandatory in request definition of the Contract. + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + // HTTP request method (GET/POST/PUT/DELETE). + method 'GET' + + // Path component of request URL is specified as follows. + urlPath('/users') + } + + response { + //... + } +} + + + +YAML + +method: PUT +url: /foo + + +It is possible to specify an absolute rather than relative url, but using urlPath is +the recommended way, as doing so makes the tests host-independent. + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + method 'GET' + + // Specifying `url` and `urlPath` in one contract is illegal. + url('http://localhost:8888/users') + } + + response { + //... + } +} + + + +YAML + +request: + method: PUT + urlPath: /foo + + +request may contain query parameters. + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + //... + + urlPath('/users') { + + // Each parameter is specified in form + // `'paramName' : paramValue` where parameter value + // may be a simple literal or one of matcher functions, + // all of which are used in this example. + queryParameters { + + // If a simple literal is used as value + // default matcher function is used (equalTo) + parameter 'limit': 100 + + // `equalTo` function simply compares passed value + // using identity operator (==). + parameter 'filter': equalTo("email") + + // `containing` function matches strings + // that contains passed substring. + parameter 'gender': value(consumer(containing("[mf]")), producer('mf')) + + // `matching` function tests parameter + // against passed regular expression. + parameter 'offset': value(consumer(matching("[0-9]+")), producer(123)) + + // `notMatching` functions tests if parameter + // does not match passed regular expression. + parameter 'loginStartsWith': value(consumer(notMatching(".{0,2}")), producer(3)) + } + } + + //... + } + + response { + //... + } +} + + + +YAML + +request: +... + queryParameters: + a: b + b: c + headers: + foo: bar + fooReq: baz + cookies: + foo: bar + fooReq: baz + body: + foo: bar + matchers: + body: + - path: $.foo + type: by_regex + value: bar + headers: + - key: foo + regex: bar +response: + status: 200 + fixedDelayMilliseconds: 1000 + headers: + foo2: bar + foo3: foo33 + fooRes: baz + body: + foo2: bar + foo3: baz + matchers: + body: + - path: $.foo2 + type: by_regex + value: bar + - path: $.foo3 + type: by_command + value: executeMe($it) + headers: + - key: foo2 + regex: bar + - key: foo3 + command: andMeToo($it) + cookies: + - key: foo2 + regex: bar + - key: foo3 + predefined: + + +request may contain additional request headers, as shown in the following example: + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + //... + + // Each header is added in form `'Header-Name' : 'Header-Value'`. + // there are also some helper methods + headers { + header 'key': 'value' + contentType(applicationJson()) + } + + //... + } + + response { + //... + } +} + + + +YAML + +request: +... +headers: + foo: bar + fooReq: baz + + +request may contain additional request cookies, as shown in the following example: + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + //... + + // Each Cookies is added in form `'Cookie-Key' : 'Cookie-Value'`. + // there are also some helper methods + cookies { + cookie 'key': 'value' + cookie('another_key', 'another_value') + } + + //... + } + + response { + //... + } +} + + + +YAML + +request: +... +cookies: + foo: bar + fooReq: baz + + +request may contain a request body: + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + //... + + // Currently only JSON format of request body is supported. + // Format will be determined from a header or body's content. + body '''{ "login" : "john", "name": "John The Contract" }''' + } + + response { + //... + } +} + + + +YAML + +request: +... +body: + foo: bar + + +request may contain multipart elements. To include multipart elements, use the +multipart method/section, as shown in the following examples + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract contractDsl = org.springframework.cloud.contract.spec.Contract.make { + request { + method "PUT" + url "/multipart" + headers { + contentType('multipart/form-data;boundary=AaB03x') + } + multipart( + // key (parameter name), value (parameter value) pair + formParameter: $(c(regex('".+"')), p('"formParameterValue"')), + someBooleanParameter: $(c(regex(anyBoolean())), p('true')), + // a named parameter (e.g. with `file` name) that represents file with + // `name` and `content`. You can also call `named("fileName", "fileContent")` + file: named( + // name of the file + name: $(c(regex(nonEmpty())), p('filename.csv')), + // content of the file + content: $(c(regex(nonEmpty())), p('file content')), + // content type for the part + contentType: $(c(regex(nonEmpty())), p('application/json'))) + ) + } + response { + status 200 + } +} + + + +YAML + +request: + method: PUT + url: /multipart + headers: + Content-Type: multipart/form-data;boundary=AaB03x + multipart: + params: + # key (parameter name), value (parameter value) pair + formParameter: '"formParameterValue"' + someBooleanParameter: true + named: + - paramName: file + fileName: filename.csv + fileContent: file content + matchers: + multipart: + params: + - key: formParameter + regex: ".+" + - key: someBooleanParameter + predefined: any_boolean + named: + - paramName: file + fileName: + predefined: non_empty + fileContent: + predefined: non_empty +response: + status: 200 + + +In the preceding example, we define parameters in either of two ways: + +Groovy DSL + +Directly, by using the map notation, where the value can be a dynamic property (such as +formParameter: $(consumer(…​), producer(…​))). + + +By using the named(…​) method that lets you set a named parameter. A named parameter +can set a name and content. You can call it either via a method with two arguments, +such as named("fileName", "fileContent"), or via a map notation, such as +named(name: "fileName", content: "fileContent"). + + + +YAML + +The multipart parameters are set via multipart.params section + + +The named parameters (the fileName and fileContent for a given parameter name) +can be set via the multipart.named section. That section contains +the paramName (name of the parameter), fileName (name of the file), +fileContent (content of the file) fields + + +The dynamic bits can be set via the matchers.multipart section + + +for parameters use the params section that can accept +regex or a predefined regular expression + + +for named params use the named section where first you +define the parameter name via paramName and then you can pass the +parametrization of either fileName or fileContent via +regex or a predefined regular expression + + + + +From this contract, the generated test is as follows: +// given: + MockMvcRequestSpecification request = given() + .header("Content-Type", "multipart/form-data;boundary=AaB03x") + .param("formParameter", "\"formParameterValue\"") + .param("someBooleanParameter", "true") + .multiPart("file", "filename.csv", "file content".getBytes()); + +// when: + ResponseOptions response = given().spec(request) + .put("/multipart"); + +// then: + assertThat(response.statusCode()).isEqualTo(200); +The WireMock stub is as follows: + ''' +{ + "request" : { + "url" : "/multipart", + "method" : "PUT", + "headers" : { + "Content-Type" : { + "matches" : "multipart/form-data;boundary=AaB03x.*" + } + }, + "bodyPatterns" : [ { + "matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"formParameter\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n\\".+\\"\\r\\n--\\\\1.*" + }, { + "matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"someBooleanParameter\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n(true|false)\\r\\n--\\\\1.*" + }, { + "matches" : ".*--(.*)\\r\\nContent-Disposition: form-data; name=\\"file\\"; filename=\\"[\\\\S\\\\s]+\\"\\r\\n(Content-Type: .*\\r\\n)?(Content-Length: \\\\d+\\r\\n)?\\r\\n[\\\\S\\\\s]+\\r\\n--\\\\1.*" + } ] + }, + "response" : { + "status" : 200, + "transformers" : [ "response-template", "foo-transformer" ] + } +} + ''' +
+
+Response +The response must contain an HTTP status code and may contain other information. The +following code shows an example: + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + //... + } + response { + // Status code sent by the server + // in response to request specified above. + status 200 + } +} + + + +YAML + +response: +... +status: 200 + + +Besides status, the response may contain headers, cookies and a body, both of which are +specified the same way as in the request (see the previous paragraph). +
+
+Dynamic properties +The contract can contain some dynamic properties: timestamps, IDs, and so on. You do not +want to force the consumers to stub their clocks to always return the same value of time +so that it gets matched by the stub. +For Groovy DSL you can provide the dynamic parts in your contracts +in two ways: pass them directly in the body or set them in separate sections called +testMatchers and stubMatchers. +For YAML you can only use the matchers section. +
+Dynamic properties inside the body + +This section is valid only for Groovy DSL. Check out the + section for YAML examples of a similar feature. + +You can set the properties inside the body either with the value method or, if you use +the Groovy map notation, with $(). The following example shows how to set dynamic +properties with the value method: +value(consumer(...), producer(...)) +value(c(...), p(...)) +value(stub(...), test(...)) +value(client(...), server(...)) +The following example shows how to set dynamic properties with $(): +$(consumer(...), producer(...)) +$(c(...), p(...)) +$(stub(...), test(...)) +$(client(...), server(...)) +Both approaches work equally well. stub and client methods are aliases over the consumer +method. Subsequent sections take a closer look at what you can do with those values. +
+
+Regular expressions + +This section is valid only for Groovy DSL. Check out the + section for YAML examples of a similar feature. + +You can use regular expressions to write your requests in Contract DSL. Doing so is +particularly useful when you want to indicate that a given response should be provided +for requests that follow a given pattern. Also, you can use regular expressions when you +need to use patterns and not exact values both for your test and your server side tests. +The following example shows how to use regular expressions to write a request: +org.springframework.cloud.contract.spec.Contract.make { + request { + method('GET') + url $(consumer(~/\/[0-9]{2}/), producer('/12')) + } + response { + status 200 + body( + id: $(anyNumber()), + surname: $( + consumer('Kowalsky'), + producer(regex('[a-zA-Z]+')) + ), + name: 'Jan', + created: $(consumer('2014-02-02 12:23:43'), producer(execute('currentDate(it)'))), + correlationId: value(consumer('5d1f9fef-e0dc-4f3d-a7e4-72d2220dd827'), + producer(regex('[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}')) + ) + ) + headers { + header 'Content-Type': 'text/plain' + } + } +} +You can also provide only one side of the communication with a regular expression. If you +do so, then the contract engine automatically provides the generated string that matches +the provided regular expression. The following code shows an example: +org.springframework.cloud.contract.spec.Contract.make { + request { + method 'PUT' + url value(consumer(regex('/foo/[0-9]{5}'))) + body([ + requestElement: $(consumer(regex('[0-9]{5}'))) + ]) + headers { + header('header', $(consumer(regex('application\\/vnd\\.fraud\\.v1\\+json;.*')))) + } + } + response { + status 200 + body([ + responseElement: $(producer(regex('[0-9]{7}'))) + ]) + headers { + contentType("application/vnd.fraud.v1+json") + } + } +} +In the preceding example, the opposite side of the communication has the respective data +generated for request and response. +Spring Cloud Contract comes with a series of predefined regular expressions that you can +use in your contracts, as shown in the following example: +protected static final Pattern TRUE_OR_FALSE = Pattern.compile(/(true|false)/) +protected static final Pattern ONLY_ALPHA_UNICODE = Pattern.compile(/[\p{L}]*/) +protected static final Pattern NUMBER = Pattern.compile('-?(\\d*\\.\\d+|\\d+)') +protected static final Pattern IP_ADDRESS = Pattern.compile('([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])') +protected static final Pattern HOSTNAME_PATTERN = Pattern.compile('((http[s]?|ftp):/)/?([^:/\\s]+)(:[0-9]{1,5})?') +protected static final Pattern EMAIL = Pattern.compile('[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6}') +protected static final Pattern URL = UrlHelper.URL +protected static final Pattern UUID = Pattern.compile('[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}') +protected static final Pattern ANY_DATE = Pattern.compile('(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])') +protected static final Pattern ANY_DATE_TIME = Pattern.compile('([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])') +protected static final Pattern ANY_TIME = Pattern.compile('(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])') +protected static final Pattern NON_EMPTY = Pattern.compile(/[\S\s]+/) +protected static final Pattern NON_BLANK = Pattern.compile(/^\s*\S[\S\s]*/) +protected static final Pattern ISO8601_WITH_OFFSET = Pattern.compile(/([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.\d{3})?(Z|[+-][01]\d:[0-5]\d)/) + +protected static Pattern anyOf(String... values){ + return Pattern.compile(values.collect({"^$it\$"}).join("|")) +} + +String onlyAlphaUnicode() { + return ONLY_ALPHA_UNICODE.pattern() +} + +String number() { + return NUMBER.pattern() +} + +String anyBoolean() { + return TRUE_OR_FALSE.pattern() +} + +String ipAddress() { + return IP_ADDRESS.pattern() +} + +String hostname() { + return HOSTNAME_PATTERN.pattern() +} + +String email() { + return EMAIL.pattern() +} + +String url() { + return URL.pattern() +} + +String uuid(){ + return UUID.pattern() +} + +String isoDate() { + return ANY_DATE.pattern() +} + +String isoDateTime() { + return ANY_DATE_TIME.pattern() +} + +String isoTime() { + return ANY_TIME.pattern() +} + +String iso8601WithOffset() { + return ISO8601_WITH_OFFSET.pattern() +} + +String nonEmpty() { + return NON_EMPTY.pattern() +} + +String nonBlank() { + return NON_BLANK.pattern() +} +In your contract, you can use it as shown in the following example: +Contract dslWithOptionalsInString = Contract.make { + priority 1 + request { + method POST() + url '/users/password' + headers { + contentType(applicationJson()) + } + body( + email: $(consumer(optional(regex(email()))), producer('abc@abc.com')), + callback_url: $(consumer(regex(hostname())), producer('https://partners.com')) + ) + } + response { + status 404 + headers { + contentType(applicationJson()) + } + body( + code: value(consumer("123123"), producer(optional("123123"))), + message: "User not found by email = [${value(producer(regex(email())), consumer('not.existing@user.com'))}]" + ) + } +} +
+
+Passing Optional Parameters + +This section is valid only for Groovy DSL. Check out the + section for YAML examples of a similar feature. + +It is possible to provide optional parameters in your contract. However, you can provide +optional parameters only for the following: + + +STUB side of the Request + + +TEST side of the Response + + +The following example shows how to provide optional parameters: +org.springframework.cloud.contract.spec.Contract.make { + priority 1 + request { + method 'POST' + url '/users/password' + headers { + contentType(applicationJson()) + } + body( + email: $(consumer(optional(regex(email()))), producer('abc@abc.com')), + callback_url: $(consumer(regex(hostname())), producer('https://partners.com')) + ) + } + response { + status 404 + headers { + header 'Content-Type': 'application/json' + } + body( + code: value(consumer("123123"), producer(optional("123123"))) + ) + } +} +By wrapping a part of the body with the optional() method, you create a regular +expression that must be present 0 or more times. +If you use Spock for, the following test would be generated from the previous example: +""" + given: + def request = given() + .header("Content-Type", "application/json") + .body('''{"email":"abc@abc.com","callback_url":"https://partners.com"}''') + + when: + def response = given().spec(request) + .post("/users/password") + + then: + response.statusCode == 404 + response.header('Content-Type') == 'application/json' + and: + DocumentContext parsedJson = JsonPath.parse(response.body.asString()) + assertThatJson(parsedJson).field("['code']").matches("(123123)?") +""" +The following stub would also be generated: +''' +{ + "request" : { + "url" : "/users/password", + "method" : "POST", + "bodyPatterns" : [ { + "matchesJsonPath" : "$[?(@.['email'] =~ /([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\\\.[a-zA-Z]{2,6})?/)]" + }, { + "matchesJsonPath" : "$[?(@.['callback_url'] =~ /((http[s]?|ftp):\\\\/)\\\\/?([^:\\\\/\\\\s]+)(:[0-9]{1,5})?/)]" + } ], + "headers" : { + "Content-Type" : { + "equalTo" : "application/json" + } + } + }, + "response" : { + "status" : 404, + "body" : "{\\"code\\":\\"123123\\",\\"message\\":\\"User not found by email == [not.existing@user.com]\\"}", + "headers" : { + "Content-Type" : "application/json" + } + }, + "priority" : 1 +} +''' +
+
+Executing Custom Methods on the Server Side + +This section is valid only for Groovy DSL. Check out the + section for YAML examples of a similar feature. + +You can define a method call that executes on the server side during the test. Such a +method can be added to the class defined as "baseClassForTests" in the configuration. The +following code shows an example of the contract portion of the test case: +org.springframework.cloud.contract.spec.Contract.make { + request { + method 'PUT' + url $(consumer(regex('^/api/[0-9]{2}$')), producer('/api/12')) + headers { + header 'Content-Type': 'application/json' + } + body '''\ + [{ + "text": "Gonna see you at Warsaw" + }] + ''' + } + response { + body ( + path: $(consumer('/api/12'), producer(regex('^/api/[0-9]{2}$'))), + correlationId: $(consumer('1223456'), producer(execute('isProperCorrelationId($it)'))) + ) + status 200 + } +} +The following code shows the base class portion of the test case: +abstract class BaseMockMvcSpec extends Specification { + + def setup() { + RestAssuredMockMvc.standaloneSetup(new PairIdController()) + } + + void isProperCorrelationId(Integer correlationId) { + assert correlationId == 123456 + } + + void isEmpty(String value) { + assert value == null + } + +} + +You cannot use both a String and execute to perform concatenation. For +example, calling header('Authorization', 'Bearer ' + execute('authToken()')) leads to +improper results. Instead, call header('Authorization', execute('authToken()')) and +ensure that the authToken() method returns everything you need. + +The type of the object read from the JSON can be one of the following, depending on the +JSON path: + + +String: If you point to a String value in the JSON. + + +JSONArray: If you point to a List in the JSON. + + +Map: If you point to a Map in the JSON. + + +Number: If you point to Integer, Double etc. in the JSON. + + +Boolean: If you point to a Boolean in the JSON. + + +In the request part of the contract, you can specify that the body should be taken from +a method. + +You must provide both the consumer and the producer side. The execute part +is applied for the whole body - not for parts of it. + +The following example shows how to read an object from JSON: +Contract contractDsl = Contract.make { + request { + method 'GET' + url '/something' + body( + $(c("foo"), p(execute("hashCode()"))) + ) + } + response { + status 200 + } +} +The preceding example results in calling the hashCode() method in the request body. +It should resemble the following code: +// given: + MockMvcRequestSpecification request = given() + .body(hashCode()); + +// when: + ResponseOptions response = given().spec(request) + .get("/something"); + +// then: + assertThat(response.statusCode()).isEqualTo(200); +
+
+Referencing the Request from the Response +The best situation is to provide fixed values, but sometimes you need to reference a +request in your response. +If you’re writing contracts using Groovy DSL, you can use the fromRequest() method, which lets +you reference a bunch of elements from the HTTP request. You can use the following +options: + + +fromRequest().url(): Returns the request URL and query parameters. + + +fromRequest().query(String key): Returns the first query parameter with a given name. + + +fromRequest().query(String key, int index): Returns the nth query parameter with a +given name. + + +fromRequest().path(): Returns the full path. + + +fromRequest().path(int index): Returns the nth path element. + + +fromRequest().header(String key): Returns the first header with a given name. + + +fromRequest().header(String key, int index): Returns the nth header with a given name. + + +fromRequest().body(): Returns the full request body. + + +fromRequest().body(String jsonPath): Returns the element from the request that +matches the JSON Path. + + +If you’re using the YAML contract definition you have to use the +Handlebars {{{ }}} notation with custom, Spring Cloud Contract + functions to achieve this. + + +{{{ request.url }}}: Returns the request URL and query parameters. + + +{{{ request.query.key.[index] }}}: Returns the nth query parameter with a given name. +E.g. for key foo, first entry {{{ request.query.foo.[0] }}} + + +{{{ request.path }}}: Returns the full path. + + +{{{ request.path.[index] }}}: Returns the nth path element. E.g. +for first entry `{{{ request.path.[0] }}} + + +{{{ request.headers.key }}}: Returns the first header with a given name. + + +{{{ request.headers.key.[index] }}}: Returns the nth header with a given name. + + +{{{ request.body }}}: Returns the full request body. + + +{{{ jsonpath this 'your.json.path' }}}: Returns the element from the request that +matches the JSON Path. E.g. for json path $.foo - {{{ jsonpath this '$.foo' }}} + + +Consider the following contract: + +Groovy DSL + +Contract contractDsl = Contract.make { + request { + method 'GET' + url('/api/v1/xxxx') { + queryParameters { + parameter("foo", "bar") + parameter("foo", "bar2") + } + } + headers { + header(authorization(), "secret") + header(authorization(), "secret2") + } + body(foo: "bar", baz: 5) + } + response { + status 200 + headers { + header(authorization(), "foo ${fromRequest().header(authorization())} bar") + } + body( + url: fromRequest().url(), + path: fromRequest().path(), + pathIndex: fromRequest().path(1), + param: fromRequest().query("foo"), + paramIndex: fromRequest().query("foo", 1), + authorization: fromRequest().header("Authorization"), + authorization2: fromRequest().header("Authorization", 1), + fullBody: fromRequest().body(), + responseFoo: fromRequest().body('$.foo'), + responseBaz: fromRequest().body('$.baz'), + responseBaz2: "Bla bla ${fromRequest().body('$.foo')} bla bla" + ) + } +} + + + +YAML + +request: + method: GET + url: /api/v1/xxxx + queryParameters: + foo: + - bar + - bar2 + headers: + Authorization: + - secret + - secret2 + body: + foo: bar + baz: 5 +response: + status: 200 + headers: + Authorization: "foo {{{ request.headers.Authorization.0 }}} bar" + body: + url: "{{{ request.url }}}" + path: "{{{ request.path }}}" + pathIndex: "{{{ request.path.1 }}}" + param: "{{{ request.query.foo }}}" + paramIndex: "{{{ request.query.foo.1 }}}" + authorization: "{{{ request.headers.Authorization.0 }}}" + authorization2: "{{{ request.headers.Authorization.1 }}" + fullBody: "{{{ request.body }}}" + responseFoo: "{{{ jsonpath this '$.foo' }}}" + responseBaz: "{{{ jsonpath this '$.baz' }}}" + responseBaz2: "Bla bla {{{ jsonpath this '$.foo' }}} bla bla" + + +Running a JUnit test generation leads to a test that resembles the following example: +// given: + MockMvcRequestSpecification request = given() + .header("Authorization", "secret") + .header("Authorization", "secret2") + .body("{\"foo\":\"bar\",\"baz\":5}"); + +// when: + ResponseOptions response = given().spec(request) + .queryParam("foo","bar") + .queryParam("foo","bar2") + .get("/api/v1/xxxx"); + +// then: + assertThat(response.statusCode()).isEqualTo(200); + assertThat(response.header("Authorization")).isEqualTo("foo secret bar"); +// and: + DocumentContext parsedJson = JsonPath.parse(response.getBody().asString()); + assertThatJson(parsedJson).field("['fullBody']").isEqualTo("{\"foo\":\"bar\",\"baz\":5}"); + assertThatJson(parsedJson).field("['authorization']").isEqualTo("secret"); + assertThatJson(parsedJson).field("['authorization2']").isEqualTo("secret2"); + assertThatJson(parsedJson).field("['path']").isEqualTo("/api/v1/xxxx"); + assertThatJson(parsedJson).field("['param']").isEqualTo("bar"); + assertThatJson(parsedJson).field("['paramIndex']").isEqualTo("bar2"); + assertThatJson(parsedJson).field("['pathIndex']").isEqualTo("v1"); + assertThatJson(parsedJson).field("['responseBaz']").isEqualTo(5); + assertThatJson(parsedJson).field("['responseFoo']").isEqualTo("bar"); + assertThatJson(parsedJson).field("['url']").isEqualTo("/api/v1/xxxx?foo=bar&foo=bar2"); + assertThatJson(parsedJson).field("['responseBaz2']").isEqualTo("Bla bla bar bla bla"); +As you can see, elements from the request have been properly referenced in the response. +The generated WireMock stub should resemble the following example: +{ + "request" : { + "urlPath" : "/api/v1/xxxx", + "method" : "POST", + "headers" : { + "Authorization" : { + "equalTo" : "secret2" + } + }, + "queryParameters" : { + "foo" : { + "equalTo" : "bar2" + } + }, + "bodyPatterns" : [ { + "matchesJsonPath" : "$[?(@.['baz'] == 5)]" + }, { + "matchesJsonPath" : "$[?(@.['foo'] == 'bar')]" + } ] + }, + "response" : { + "status" : 200, + "body" : "{\"authorization\":\"{{{request.headers.Authorization.[0]}}}\",\"path\":\"{{{request.path}}}\",\"responseBaz\":{{{jsonpath this '$.baz'}}} ,\"param\":\"{{{request.query.foo.[0]}}}\",\"pathIndex\":\"{{{request.path.[1]}}}\",\"responseBaz2\":\"Bla bla {{{jsonpath this '$.foo'}}} bla bla\",\"responseFoo\":\"{{{jsonpath this '$.foo'}}}\",\"authorization2\":\"{{{request.headers.Authorization.[1]}}}\",\"fullBody\":\"{{{escapejsonbody}}}\",\"url\":\"{{{request.url}}}\",\"paramIndex\":\"{{{request.query.foo.[1]}}}\"}", + "headers" : { + "Authorization" : "{{{request.headers.Authorization.[0]}}};foo" + }, + "transformers" : [ "response-template" ] + } +} +Sending a request such as the one presented in the request part of the contract results +in sending the following response body: +{ + "url" : "/api/v1/xxxx?foo=bar&foo=bar2", + "path" : "/api/v1/xxxx", + "pathIndex" : "v1", + "param" : "bar", + "paramIndex" : "bar2", + "authorization" : "secret", + "authorization2" : "secret2", + "fullBody" : "{\"foo\":\"bar\",\"baz\":5}", + "responseFoo" : "bar", + "responseBaz" : 5, + "responseBaz2" : "Bla bla bar bla bla" +} + +This feature works only with WireMock having a version greater than or equal +to 2.5.1. The Spring Cloud Contract Verifier uses WireMock’s +response-template response transformer. It uses Handlebars to convert the Mustache {{{ }}} templates into +proper values. Additionally, it registers two helper functions: + + + +escapejsonbody: Escapes the request body in a format that can be embedded in a JSON. + + +jsonpath: For a given parameter, find an object in the request body. + + +
+
+Registering Your Own WireMock Extension +WireMock lets you register custom extensions. By default, Spring Cloud Contract registers +the transformer, which lets you reference a request from a response. If you want to +provide your own extensions, you can register an implementation of the +org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions interface. +Since we use the spring.factories extension approach, you can create an entry in +META-INF/spring.factories file similar to the following: +org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions=\ +org.springframework.cloud.contract.stubrunner.provider.wiremock.TestWireMockExtensions +The following is an example of a custom extension: + +TestWireMockExtensions.groovy + +package org.springframework.cloud.contract.verifier.dsl.wiremock + +import com.github.tomakehurst.wiremock.extension.Extension + +/** + * Extension that registers the default transformer and the custom one + */ +class TestWireMockExtensions implements WireMockExtensions { + @Override + List<Extension> extensions() { + return [ + new DefaultResponseTransformer(), + new CustomExtension() + ] + } +} + +class CustomExtension implements Extension { + + @Override + String getName() { + return "foo-transformer" + } +} + + + +Remember to override the applyGlobally() method and set it to false if you +want the transformation to be applied only for a mapping that explicitly requires it. + +
+
+Dynamic Properties in the Matchers Sections +If you work with Pact, the following discussion may seem familiar. +Quite a few users are used to having a separation between the body and setting the +dynamic parts of a contract. +You can use two separate sections: + + +stubMatchers, which lets you define the dynamic values that should end up in a stub. +You can set it in the request or inputMessage part of your contract. + + +testMatchers, which is present in the response or outputMessage side of the +contract. + + +Currently, Spring Cloud Contract Verifier supports only JSON Path-based matchers with the +following matching possibilities: + +Groovy DSL + +For stubMatchers: + + +byEquality(): The value taken from the request via the provided JSON Path must be +equal to the value provided in the contract. + + +byRegex(…​): The value taken from the request via the provided JSON Path must +match the regex. + + +byDate(): The value taken from the request via the provided JSON Path must +match the regex for an ISO Date value. + + +byTimestamp(): The value taken from the request via the provided JSON Path must +match the regex for an ISO DateTime value. + + +byTime(): The value taken from the request via the provided JSON Path must +match the regex for an ISO Time value. + + + + +For testMatchers: + + +byEquality(): The value taken from the response via the provided JSON Path must be +equal to the provided value in the contract. + + +byRegex(…​): The value taken from the response via the provided JSON Path must +match the regex. + + +byDate(): The value taken from the response via the provided JSON Path must match +the regex for an ISO Date value. + + +byTimestamp(): The value taken from the response via the provided JSON Path must +match the regex for an ISO DateTime value. + + +byTime(): The value taken from the response via the provided JSON Path must match +the regex for an ISO Time value. + + +byType(): The value taken from the response via the provided JSON Path needs to be +of the same type as the type defined in the body of the response in the contract. +byType can take a closure, in which you can set minOccurrence and maxOccurrence. +That way, you can assert the size of the flattened collection. To check the size of an +unflattened collection, use a custom method with the byCommand(…​) testMatcher. + + +byCommand(…​): The value taken from the response via the provided JSON Path is +passed as an input to the custom method that you provide. For example, +byCommand('foo($it)') results in calling a foo method to which the value matching the +JSON Path gets passed. The type of the object read from the JSON can be one of the +following, depending on the JSON path: + + +String: If you point to a String value. + + +JSONArray: If you point to a List. + + +Map: If you point to a Map. + + +Number: If you point to Integer, Double, or other kind of number. + + +Boolean: If you point to a Boolean. + + + + + + + +YAML +Please read the Groovy section for detailed explanation of +what the types mean + +For YAML the structure of a matcher looks like this +- path: $.foo + type: by_regex + value: bar +Or if you want to use one of the predefined regular expressions +[only_alpha_unicode, number, any_boolean, ip_address, hostname, +email, url, uuid, iso_date, iso_date_time, iso_time, iso_8601_with_offset, non_empty, non_blank]: +- path: $.foo + type: by_regex + predefined: only_alpha_unicode +Below you can find the allowed list of `type`s. + + +For stubMatchers: + + +by_equality + + +by_regex + + +by_date + + +by_timestamp + + +by_time + + + + +For testMatchers: + + +by_equality + + +by_regex + + +by_date + + +by_timestamp + + +by_time + + +by_type + + +there are 2 additional fields accepted: minOccurrence and maxOccurrence. + + + + +by_command + + + + +Consider the following example: + +Groovy DSL + +Contract contractDsl = Contract.make { + request { + method 'GET' + urlPath '/get' + body([ + duck: 123, + alpha: "abc", + number: 123, + aBoolean: true, + date: "2017-01-01", + dateTime: "2017-01-01T01:23:45", + time: "01:02:34", + valueWithoutAMatcher: "foo", + valueWithTypeMatch: "string", + key: [ + 'complex.key' : 'foo' + ] + ]) + stubMatchers { + jsonPath('$.duck', byRegex("[0-9]{3}")) + jsonPath('$.duck', byEquality()) + jsonPath('$.alpha', byRegex(onlyAlphaUnicode())) + jsonPath('$.alpha', byEquality()) + jsonPath('$.number', byRegex(number())) + jsonPath('$.aBoolean', byRegex(anyBoolean())) + jsonPath('$.date', byDate()) + jsonPath('$.dateTime', byTimestamp()) + jsonPath('$.time', byTime()) + jsonPath("\$.['key'].['complex.key']", byEquality()) + } + headers { + contentType(applicationJson()) + } + } + response { + status 200 + body([ + duck: 123, + alpha: "abc", + number: 123, + aBoolean: true, + date: "2017-01-01", + dateTime: "2017-01-01T01:23:45", + time: "01:02:34", + valueWithoutAMatcher: "foo", + valueWithTypeMatch: "string", + valueWithMin: [ + 1,2,3 + ], + valueWithMax: [ + 1,2,3 + ], + valueWithMinMax: [ + 1,2,3 + ], + valueWithMinEmpty: [], + valueWithMaxEmpty: [], + key: [ + 'complex.key' : 'foo' + ] + ]) + testMatchers { + // asserts the jsonpath value against manual regex + jsonPath('$.duck', byRegex("[0-9]{3}")) + // asserts the jsonpath value against the provided value + jsonPath('$.duck', byEquality()) + // asserts the jsonpath value against some default regex + jsonPath('$.alpha', byRegex(onlyAlphaUnicode())) + jsonPath('$.alpha', byEquality()) + jsonPath('$.number', byRegex(number())) + jsonPath('$.aBoolean', byRegex(anyBoolean())) + // asserts vs inbuilt time related regex + jsonPath('$.date', byDate()) + jsonPath('$.dateTime', byTimestamp()) + jsonPath('$.time', byTime()) + // asserts that the resulting type is the same as in response body + jsonPath('$.valueWithTypeMatch', byType()) + jsonPath('$.valueWithMin', byType { + // results in verification of size of array (min 1) + minOccurrence(1) + }) + jsonPath('$.valueWithMax', byType { + // results in verification of size of array (max 3) + maxOccurrence(3) + }) + jsonPath('$.valueWithMinMax', byType { + // results in verification of size of array (min 1 & max 3) + minOccurrence(1) + maxOccurrence(3) + }) + jsonPath('$.valueWithMinEmpty', byType { + // results in verification of size of array (min 0) + minOccurrence(0) + }) + jsonPath('$.valueWithMaxEmpty', byType { + // results in verification of size of array (max 0) + maxOccurrence(0) + }) + // will execute a method `assertThatValueIsANumber` + jsonPath('$.duck', byCommand('assertThatValueIsANumber($it)')) + jsonPath("\$.['key'].['complex.key']", byEquality()) + } + headers { + contentType(applicationJson()) + } + } +} + + + +YAML + +request: + method: GET + urlPath: /get + body: + duck: 123 + alpha: "abc" + number: 123 + aBoolean: true + date: "2017-01-01" + dateTime: "2017-01-01T01:23:45" + time: "01:02:34" + valueWithoutAMatcher: "foo" + valueWithTypeMatch: "string" + key: + "complex.key": 'foo' + matchers: + headers: + - key: Content-Type + regex: "application/json.*" + body: + - path: $.duck + type: by_regex + value: "[0-9]{3}" + - path: $.duck + type: by_equality + - path: $.alpha + type: by_regex + predefined: only_alpha_unicode + - path: $.alpha + type: by_equality + - path: $.number + type: by_regex + predefined: number + - path: $.aBoolean + type: by_regex + predefined: any_boolean + - path: $.date + type: by_date + - path: $.dateTime + type: by_timestamp + - path: $.time + type: by_time + - path: "$.['key'].['complex.key']" + type: by_equality + headers: + Content-Type: application/json +response: + status: 200 + body: + duck: 123 + alpha: "abc" + number: 123 + aBoolean: true + date: "2017-01-01" + dateTime: "2017-01-01T01:23:45" + time: "01:02:34" + valueWithoutAMatcher: "foo" + valueWithTypeMatch: "string" + valueWithMin: + - 1 + - 2 + - 3 + valueWithMax: + - 1 + - 2 + - 3 + valueWithMinMax: + - 1 + - 2 + - 3 + valueWithMinEmpty: [] + valueWithMaxEmpty: [] + key: + 'complex.key' : 'foo' + matchers: + headers: + - key: Content-Type + regex: "application/json.*" + body: + - path: $.duck + type: by_regex + value: "[0-9]{3}" + - path: $.duck + type: by_equality + - path: $.alpha + type: by_regex + predefined: only_alpha_unicode + - path: $.alpha + type: by_equality + - path: $.number + type: by_regex + predefined: number + - path: $.aBoolean + type: by_regex + predefined: any_boolean + - path: $.date + type: by_date + - path: $.dateTime + type: by_timestamp + - path: $.time + type: by_time + - path: $.valueWithTypeMatch + type: by_type + - path: $.valueWithMin + type: by_type + minOccurrence: 1 + - path: $.valueWithMax + type: by_type + maxOccurrence: 3 + - path: $.valueWithMinMax + type: by_type + minOccurrence: 1 + maxOccurrence: 3 + - path: $.valueWithMinEmpty + type: by_type + minOccurrence: 0 + - path: $.valueWithMaxEmpty + type: by_type + maxOccurrence: 0 + - path: $.duck + type: by_command + value: assertThatValueIsANumber($it) + headers: + Content-Type: application/json + + +In the preceding example, you can see the dynamic portions of the contract in the +matchers sections. For the request part, you can see that, for all fields but +valueWithoutAMatcher, the values of the regular expressions that the stub should +contain are explicitly set. For the valueWithoutAMatcher, the verification takes place +in the same way as without the use of matchers. In that case, the test performs an +equality check. +For the response side in the testMatchers section, we define the dynamic parts in a +similar manner. The only difference is that the byType matchers are also present. The +verifier engine checks four fields to verify whether the response from the test +has a value for which the JSON path matches the given field, is of the same type as the one +defined in the response body, and passes the following check (based on the method being called): + + +For $.valueWithTypeMatch, the engine checks whether the type is the same. + + +For $.valueWithMin, the engine check the type and asserts whether the size is greater +than or equal to the minimum occurrence. + + +For $.valueWithMax, the engine checks the type and asserts whether the size is +smaller than or equal to the maximum occurrence. + + +For $.valueWithMinMax, the engine checks the type and asserts whether the size is +between the min and maximum occurrence. + + +The resulting test would resemble the following example (note that an and section +separates the autogenerated assertions and the assertion from matchers): +// given: + MockMvcRequestSpecification request = given() + .header("Content-Type", "application/json") + .body("{\"duck\":123,\"alpha\":\"abc\",\"number\":123,\"aBoolean\":true,\"date\":\"2017-01-01\",\"dateTime\":\"2017-01-01T01:23:45\",\"time\":\"01:02:34\",\"valueWithoutAMatcher\":\"foo\",\"valueWithTypeMatch\":\"string\"}"); + +// when: + ResponseOptions response = given().spec(request) + .get("/get"); + +// then: + assertThat(response.statusCode()).isEqualTo(200); + assertThat(response.header("Content-Type")).matches("application/json.*"); +// and: + DocumentContext parsedJson = JsonPath.parse(response.getBody().asString()); + assertThatJson(parsedJson).field("valueWithoutAMatcher").isEqualTo("foo"); +// and: + assertThat(parsedJson.read("$.duck", String.class)).matches("[0-9]{3}"); + assertThat(parsedJson.read("$.duck", Integer.class)).isEqualTo(123); + assertThat(parsedJson.read("$.alpha", String.class)).matches("[\\p{L}]*"); + assertThat(parsedJson.read("$.alpha", String.class)).isEqualTo("abc"); + assertThat(parsedJson.read("$.number", String.class)).matches("-?\\d*(\\.\\d+)?"); + assertThat(parsedJson.read("$.aBoolean", String.class)).matches("(true|false)"); + assertThat(parsedJson.read("$.date", String.class)).matches("(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])"); + assertThat(parsedJson.read("$.dateTime", String.class)).matches("([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])"); + assertThat(parsedJson.read("$.time", String.class)).matches("(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])"); + assertThat((Object) parsedJson.read("$.valueWithTypeMatch")).isInstanceOf(java.lang.String.class); + assertThat((Object) parsedJson.read("$.valueWithMin")).isInstanceOf(java.util.List.class); + assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMin", java.util.Collection.class)).hasSizeGreaterThanOrEqualTo(1); + assertThat((Object) parsedJson.read("$.valueWithMax")).isInstanceOf(java.util.List.class); + assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMax", java.util.Collection.class)).hasSizeLessThanOrEqualTo(3); + assertThat((Object) parsedJson.read("$.valueWithMinMax")).isInstanceOf(java.util.List.class); + assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMinMax", java.util.Collection.class)).hasSizeBetween(1, 3); + assertThat((Object) parsedJson.read("$.valueWithMinEmpty")).isInstanceOf(java.util.List.class); + assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMinEmpty", java.util.Collection.class)).hasSizeGreaterThanOrEqualTo(0); + assertThat((Object) parsedJson.read("$.valueWithMaxEmpty")).isInstanceOf(java.util.List.class); + assertThat((java.lang.Iterable) parsedJson.read("$.valueWithMaxEmpty", java.util.Collection.class)).hasSizeLessThanOrEqualTo(0); + assertThatValueIsANumber(parsedJson.read("$.duck")); + +Notice that, for the byCommand method, the example calls the +assertThatValueIsANumber. This method must be defined in the test base class or be +statically imported to your tests. Notice that the byCommand call was converted to +assertThatValueIsANumber(parsedJson.read("$.duck"));. That means that the engine took +the method name and passed the proper JSON path as a parameter to it. + +The resulting WireMock stub is in the following example: + ''' +{ + "request" : { + "urlPath" : "/get", + "method" : "POST", + "headers" : { + "Content-Type" : { + "matches" : "application/json.*" + } + }, + "bodyPatterns" : [ { + "matchesJsonPath" : "$[?(@.['valueWithoutAMatcher'] == 'foo')]" + }, { + "matchesJsonPath" : "$[?(@.['valueWithTypeMatch'] == 'string')]" + }, { + "matchesJsonPath" : "$.['list'].['some'].['nested'][?(@.['anothervalue'] == 4)]" + }, { + "matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['anothervalue'] == 4)]" + }, { + "matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['json'] == 'with value')]" + }, { + "matchesJsonPath" : "$[?(@.duck =~ /([0-9]{3})/)]" + }, { + "matchesJsonPath" : "$[?(@.duck == 123)]" + }, { + "matchesJsonPath" : "$[?(@.alpha =~ /([\\\\p{L}]*)/)]" + }, { + "matchesJsonPath" : "$[?(@.alpha == 'abc')]" + }, { + "matchesJsonPath" : "$[?(@.number =~ /(-?(\\\\d*\\\\.\\\\d+|\\\\d+))/)]" + }, { + "matchesJsonPath" : "$[?(@.aBoolean =~ /((true|false))/)]" + }, { + "matchesJsonPath" : "$[?(@.date =~ /((\\\\d\\\\d\\\\d\\\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01]))/)]" + }, { + "matchesJsonPath" : "$[?(@.dateTime =~ /(([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]" + }, { + "matchesJsonPath" : "$[?(@.time =~ /((2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]" + }, { + "matchesJsonPath" : "$.list.some.nested[?(@.json =~ /(.*)/)]" + } ] + }, + "response" : { + "status" : 200, + "body" : "{\\"date\\":\\"2017-01-01\\",\\"dateTime\\":\\"2017-01-01T01:23:45\\",\\"number\\":123,\\"aBoolean\\":true,\\"duck\\":123,\\"alpha\\":\\"abc\\",\\"valueWithMin\\":[1,2,3],\\"time\\":\\"01:02:34\\",\\"valueWithTypeMatch\\":\\"string\\",\\"valueWithMax\\":[1,2,3],\\"valueWithMinMax\\":[1,2,3],\\"valueWithoutAMatcher\\":\\"foo\\"}", + "headers" : { + "Content-Type" : "application/json" + } + } +} +''' + +If you use a matcher, then the part of the request aned response that the +matcher addresses with the JSON Path gets removed from the assertion. In the case of +verifying a collection, you must create matchers for all the elements of the +collection. + +Consider the following example: +Contract.make { + request { + method 'GET' + url("/foo") + } + response { + status 200 + body(events: [[ + operation : 'EXPORT', + eventId : '16f1ed75-0bcc-4f0d-a04d-3121798faf99', + status : 'OK' + ], [ + operation : 'INPUT_PROCESSING', + eventId : '3bb4ac82-6652-462f-b6d1-75e424a0024a', + status : 'OK' + ] + ] + ) + testMatchers { + jsonPath('$.events[0].operation', byRegex('.+')) + jsonPath('$.events[0].eventId', byRegex('^([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})$')) + jsonPath('$.events[0].status', byRegex('.+')) + } + } +} +The preceding code leads to creating the following test (the code block shows only the assertion section): +and: + DocumentContext parsedJson = JsonPath.parse(response.body.asString()) + assertThatJson(parsedJson).array("['events']").contains("['eventId']").isEqualTo("16f1ed75-0bcc-4f0d-a04d-3121798faf99") + assertThatJson(parsedJson).array("['events']").contains("['operation']").isEqualTo("EXPORT") + assertThatJson(parsedJson).array("['events']").contains("['operation']").isEqualTo("INPUT_PROCESSING") + assertThatJson(parsedJson).array("['events']").contains("['eventId']").isEqualTo("3bb4ac82-6652-462f-b6d1-75e424a0024a") + assertThatJson(parsedJson).array("['events']").contains("['status']").isEqualTo("OK") +and: + assertThat(parsedJson.read("\$.events[0].operation", String.class)).matches(".+") + assertThat(parsedJson.read("\$.events[0].eventId", String.class)).matches("^([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})\$") + assertThat(parsedJson.read("\$.events[0].status", String.class)).matches(".+") +As you can see, the assertion is malformed. Only the first element of the array got +asserted. In order to fix this, you should apply the assertion to the whole $.events +collection and assert it with the byCommand(…​) method. +
+
+
+JAX-RS Support +The Spring Cloud Contract Verifier supports the JAX-RS 2 Client API. The base class needs +to define protected WebTarget webTarget and server initialization. The only option for +testing JAX-RS API is to start a web server. Also, a request with a body needs to have a +content type set. Otherwise, the default of application/octet-stream gets used. +In order to use JAX-RS mode, use the following settings: +testMode == 'JAXRSCLIENT' +The following example shows a generated test API: +''' + // when: + Response response = webTarget + .path("/users") + .queryParam("limit", "10") + .queryParam("offset", "20") + .queryParam("filter", "email") + .queryParam("sort", "name") + .queryParam("search", "55") + .queryParam("age", "99") + .queryParam("name", "Denis.Stepanov") + .queryParam("email", "bob@email.com") + .request() + .method("GET"); + + String responseAsString = response.readEntity(String.class); + + // then: + assertThat(response.getStatus()).isEqualTo(200); + // and: + DocumentContext parsedJson = JsonPath.parse(responseAsString); + assertThatJson(parsedJson).field("['property1']").isEqualTo("a"); +''' +
+
+Async Support +If you’re using asynchronous communication on the server side (your controllers are +returning Callable, DeferredResult, and so on), then, inside your contract, you must +provide a sync() method in the response section. The following code shows an example: + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + method GET() + url '/get' + } + response { + status 200 + body 'Passed' + async() + } +} + + + +YAML + +response: + async: true + + +You can also use the fixedDelayMilliseconds method / property to add delay to your stubs. + +Groovy DSL + +org.springframework.cloud.contract.spec.Contract.make { + request { + method GET() + url '/get' + } + response { + status 200 + body 'Passed' + fixedDelayMilliseconds 1000 + } +} + + + +YAML + +response: + fixedDelayMilliseconds: 1000 + + +
+
+Working with Context Paths +Spring Cloud Contract supports context paths. + +The only change needed to fully support context paths is the switch on the +PRODUCER side. Also, the autogenerated tests must use EXPLICIT mode. The consumer +side remains untouched. In order for the generated test to pass, you must use EXPLICIT +mode. + + +Maven + +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <testMode>EXPLICIT</testMode> + </configuration> +</plugin> + + + +Gradle + +contracts { + testMode = 'EXPLICIT' +} + + +That way, you generate a test that DOES NOT use MockMvc. It means that you generate +real requests and you need to setup your generated test’s base class to work on a real +socket. +Consider the following contract: +org.springframework.cloud.contract.spec.Contract.make { + request { + method 'GET' + url '/my-context-path/url' + } + response { + status 200 + } +} +The following example shows how to set up a base class and Rest Assured: +import io.restassured.RestAssured; +import org.junit.Before; +import org.springframework.boot.context.embedded.LocalServerPort; +import org.springframework.boot.test.context.SpringBootTest; + +@SpringBootTest(classes = ContextPathTestingBaseClass.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) +class ContextPathTestingBaseClass { + + @LocalServerPort int port; + + @Before + public void setup() { + RestAssured.baseURI = "http://localhost"; + RestAssured.port = this.port; + } +} +If you do it this way: + + +All of your requests in the autogenerated tests are sent to the real endpoint with your +context path included (for example, /my-context-path/url). + + +Your contracts reflect that you have a context path. Your generated stubs also have +that information (for example, in the stubs, you have to call /my-context-path/url). + + +
+
+Messaging Top-Level Elements +The DSL for messaging looks a little bit different than the one that focuses on HTTP. The +following sections explain the differences: + + + + + + + + + + + + + + +
+Output Triggered by a Method +The output message can be triggered by calling a method (such as a Scheduler when a was +started and a message was sent), as shown in the following example: + +Groovy DSL + +def dsl = Contract.make { + // Human readable description + description 'Some description' + // Label by means of which the output message can be triggered + label 'some_label' + // input to the contract + input { + // the contract will be triggered by a method + triggeredBy('bookReturnedTriggered()') + } + // output message of the contract + outputMessage { + // destination to which the output message will be sent + sentTo('output') + // the body of the output message + body('''{ "bookName" : "foo" }''') + // the headers of the output message + headers { + header('BOOK-NAME', 'foo') + } + } +} + + + +YAML + +# Human readable description +description: Some description +# Label by means of which the output message can be triggered +label: some_label +input: + # the contract will be triggered by a method + triggeredBy: bookReturnedTriggered() +# output message of the contract +outputMessage: + # destination to which the output message will be sent + sentTo: output + # the body of the output message + body: + bookName: foo + # the headers of the output message + headers: + BOOK-NAME: foo + + +In the previous example case, the output message is sent to output if a method called +bookReturnedTriggered is executed. On the message publisher’s side, we generate a +test that calls that method to trigger the message. On the consumer side, you can use +the some_label to trigger the message. +
+
+Output Triggered by a Message +The output message can be triggered by receiving a message, as shown in the following +example: + +Groovy DSL + +def dsl = Contract.make { + description 'Some Description' + label 'some_label' + // input is a message + input { + // the message was received from this destination + messageFrom('input') + // has the following body + messageBody([ + bookName: 'foo' + ]) + // and the following headers + messageHeaders { + header('sample', 'header') + } + } + outputMessage { + sentTo('output') + body([ + bookName: 'foo' + ]) + headers { + header('BOOK-NAME', 'foo') + } + } +} + + + +YAML + +# Human readable description +description: Some description +# Label by means of which the output message can be triggered +label: some_label +# input is a message +input: + messageFrom: input + # has the following body + messageBody: + bookName: 'foo' + # and the following headers + messageHeaders: + sample: 'header' +# output message of the contract +outputMessage: + # destination to which the output message will be sent + sentTo: output + # the body of the output message + body: + bookName: foo + # the headers of the output message + headers: + BOOK-NAME: foo + + +In the preceding example, the output message is sent to output if a proper message is +received on the input destination. On the message publisher’s side, the engine +generates a test that sends the input message to the defined destination. On the +consumer side, you can either send a message to the input destination or use a label +(some_label in the example) to trigger the message. +
+
+Consumer/Producer + +This section is valid only for Groovy DSL. + +In HTTP, you have a notion of client/stub and `server/test notation. You can also +use those paradigms in messaging. In addition, Spring Cloud Contract Verifier also +provides the consumer and producer methods, as presented in the following example +(note that you can use either $ or value methods to provide consumer and producer +parts): +Contract.make { + label 'some_label' + input { + messageFrom value(consumer('jms:output'), producer('jms:input')) + messageBody([ + bookName: 'foo' + ]) + messageHeaders { + header('sample', 'header') + } + } + outputMessage { + sentTo $(consumer('jms:input'), producer('jms:output')) + body([ + bookName: 'foo' + ]) + } +} +
+
+Common +In the input or outputMessage section you can call assertThat with the name +of a method (e.g. assertThatMessageIsOnTheQueue()) that you have defined in the +base class or in a static import. Spring Cloud Contract will execute that method +in the generated test. +
+
+
+Multiple Contracts in One File +You can define multiple contracts in one file. Such a contract might resemble the +following example: + +Groovy DSL + +import org.springframework.cloud.contract.spec.Contract + +[ + Contract.make { + name("should post a user") + request { + method 'POST' + url('/users/1') + } + response { + status 200 + } + }, + Contract.make { + request { + method 'POST' + url('/users/2') + } + response { + status 200 + } + } +] + + + +YAML + +--- +name: should post a user +request: + method: POST + url: /users/1 +response: + status: 200 + +--- +request: + method: POST + url: /users/2 +response: + status: 200 + + +In the preceding example, one contract has the name field and the other does not. This +leads to generation of two tests that look more or less like this: +package org.springframework.cloud.contract.verifier.tests.com.hello; + +import com.example.TestBase; +import com.jayway.jsonpath.DocumentContext; +import com.jayway.jsonpath.JsonPath; +import com.jayway.restassured.module.mockmvc.specification.MockMvcRequestSpecification; +import com.jayway.restassured.response.ResponseOptions; +import org.junit.Test; + +import static com.jayway.restassured.module.mockmvc.RestAssuredMockMvc.*; +import static com.toomuchcoding.jsonassert.JsonAssertion.assertThatJson; +import static org.assertj.core.api.Assertions.assertThat; + +public class V1Test extends TestBase { + + @Test + public void validate_should_post_a_user() throws Exception { + // given: + MockMvcRequestSpecification request = given(); + + // when: + ResponseOptions response = given().spec(request) + .post("/users/1"); + + // then: + assertThat(response.statusCode()).isEqualTo(200); + } + + @Test + public void validate_withList_1() throws Exception { + // given: + MockMvcRequestSpecification request = given(); + + // when: + ResponseOptions response = given().spec(request) + .post("/users/2"); + + // then: + assertThat(response.statusCode()).isEqualTo(200); + } + +} +Notice that, for the contract that has the name field, the generated test method is named +validate_should_post_a_user. For the one that does not have the name, it is called +validate_withList_1. It corresponds to the name of the file WithList.groovy and the +index of the contract in the list. +The generated stubs is shown in the following example: +should post a user.json +1_WithList.json +As you can see, the first file got the name parameter from the contract. The second +got the name of the contract file (WithList.groovy) prefixed with the index (in this +case, the contract had an index of 1 in the list of contracts in the file). + +As you can see, it iss much better if you name your contracts because doing so makes +your tests far more meaningful. + +
+ + +Customization + +This section is valid only for Groovy DSL + +You can customize the Spring Cloud Contract Verifier by extending the DSL, as shown in +the remainder of this section. +
+Extending the DSL +You can provide your own functions to the DSL. The key requirement for this feature is to +maintain the static compatibility. Later in this document, you can see examples of: + + +Creating a JAR with reusable classes. + + +Referencing of these classes in the DSLs. + + +You can find the full example +here. +
+Common JAR +The following examples show three classes that can be reused in the DSLs. +PatternUtils contains functions used by both the consumer and the producer. +package com.example; + +import java.util.regex.Pattern; + +/** + * If you want to use {@link Pattern} directly in your tests + * then you can create a class resembling this one. It can + * contain all the {@link Pattern} you want to use in the DSL. + * + * <pre> + * {@code + * request { + * body( + * [ age: $(c(PatternUtils.oldEnough()))] + * ) + * } + * </pre> + * + * Notice that we're using both {@code $()} for dynamic values + * and {@code c()} for the consumer side. + * + * @author Marcin Grzejszczak + */ +//tag::impl[] +public class PatternUtils { + + public static String tooYoung() { + //remove::start[] + return "[0-1][0-9]"; + //remove::end[return] + } + + public static Pattern oldEnough() { + //remove::start[] + return Pattern.compile("[2-9][0-9]"); + //remove::end[return] + } + + /** + * Makes little sense but it's just an example ;) + */ + public static Pattern ok() { + //remove::start[] + return Pattern.compile("OK"); + //remove::end[return] + } +} +//end::impl[] +ConsumerUtils contains functions used by the consumer. +package com.example; + +import org.springframework.cloud.contract.spec.internal.ClientDslProperty; + +/** + * DSL Properties passed to the DSL from the consumer's perspective. + * That means that on the input side {@code Request} for HTTP + * or {@code Input} for messaging you can have a regular expression. + * On the {@code Response} for HTTP or {@code Output} for messaging + * you have to have a concrete value. + * + * @author Marcin Grzejszczak + */ +//tag::impl[] +public class ConsumerUtils { + /** + * Consumer side property. By using the {@link ClientDslProperty} + * you can omit most of boilerplate code from the perspective + * of dynamic values. Example + * + * <pre> + * {@code + * request { + * body( + * [ age: $(ConsumerUtils.oldEnough())] + * ) + * } + * </pre> + * + * That way it's in the implementation that we decide what value we will pass to the consumer + * and which one to the producer. + * + * @author Marcin Grzejszczak + */ + public static ClientDslProperty oldEnough() { + //remove::start[] + // this example is not the best one and + // theoretically you could just pass the regex instead of `ServerDslProperty` but + // it's just to show some new tricks :) + return new ClientDslProperty(PatternUtils.oldEnough(), 40); + //remove::end[return] + } + +} +//end::impl[] +ProducerUtils contains functions used by the producer. +package com.example; + +import org.springframework.cloud.contract.spec.internal.ServerDslProperty; + +/** + * DSL Properties passed to the DSL from the producer's perspective. + * That means that on the input side {@code Request} for HTTP + * or {@code Input} for messaging you have to have a concrete value. + * On the {@code Response} for HTTP or {@code Output} for messaging + * you can have a regular expression. + * + * @author Marcin Grzejszczak + */ +//tag::impl[] +public class ProducerUtils { + + /** + * Producer side property. By using the {@link ProducerUtils} + * you can omit most of boilerplate code from the perspective + * of dynamic values. Example + * + * <pre> + * {@code + * response { + * body( + * [ status: $(ProducerUtils.ok())] + * ) + * } + * </pre> + * + * That way it's in the implementation that we decide what value we will pass to the consumer + * and which one to the producer. + */ + public static ServerDslProperty ok() { + // this example is not the best one and + // theoretically you could just pass the regex instead of `ServerDslProperty` but + // it's just to show some new tricks :) + return new ServerDslProperty( PatternUtils.ok(), "OK"); + } +} +//end::impl[] +
+
+Adding the Dependency to the Project +In order for the plugins and IDE to be able to reference the common JAR classes, you need +to pass the dependency to your project. +
+
+Test the Dependency in the Project’s Dependencies +First, add the common jar dependency as a test dependency. Because your contracts files +are available on the test resources path, the common jar classes automatically become +visible in your Groovy files. The following examples show how to test the dependency: + +Maven + +<dependency> + <groupId>com.example</groupId> + <artifactId>beer-common</artifactId> + <version>${project.version}</version> + <scope>test</scope> +</dependency> + + + +Gradle + +testCompile("com.example:beer-common:0.0.1.BUILD-SNAPSHOT") + + +
+
+Test a Dependency in the Plugin’s Dependencies +Now, you must add the dependency for the plugin to reuse at runtime, as shown in the +following example: + +Maven + +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <packageWithBaseClasses>com.example</packageWithBaseClasses> + <baseClassMappings> + <baseClassMapping> + <contractPackageRegex>.*intoxication.*</contractPackageRegex> + <baseClassFQN>com.example.intoxication.BeerIntoxicationBase</baseClassFQN> + </baseClassMapping> + </baseClassMappings> + </configuration> + <dependencies> + <dependency> + <groupId>com.example</groupId> + <artifactId>beer-common</artifactId> + <version>${project.version}</version> + <scope>compile</scope> + </dependency> + </dependencies> +</plugin> + + + +Gradle + +classpath "com.example:beer-common:0.0.1.BUILD-SNAPSHOT" + + +
+
+Referencing classes in DSLs +You can now reference your classes in your DSL, as shown in the following example: +package contracts.beer.rest + +import com.example.ConsumerUtils +import com.example.ProducerUtils +import org.springframework.cloud.contract.spec.Contract + +Contract.make { + description(""" +Represents a successful scenario of getting a beer + +``` +given: + client is old enough +when: + he applies for a beer +then: + we'll grant him the beer +``` + +""") + request { + method 'POST' + url '/check' + body( + age: $(ConsumerUtils.oldEnough()) + ) + headers { + contentType(applicationJson()) + } + } + response { + status 200 + body(""" + { + "status": "${value(ProducerUtils.ok())}" + } + """) + headers { + contentType(applicationJson()) + } + } +} +
+
+ + +Using the Pluggable Architecture +You may encounter cases where you have your contracts have been defined in other formats, +such as YAML, RAML or PACT. In those cases, you still want to benefit from the automatic +generation of tests and stubs. You can add your own implementation for generating both +tests and stubs. Also, you can customize the way tests are generated (for example, you +can generate tests for other languages) and the way stubs are generated (for example, you +can generate stubs for other HTTP server implementations). +
+Custom Contract Converter +The ContractConverter interface lets you register your own implementation of a contract +structure converter. The following code listing shows the ContractConverter interface: +package org.springframework.cloud.contract.spec + +/** + * Converter to be used to convert FROM {@link File} TO {@link Contract} + * and from {@link Contract} to {@code T} + * + * @param <T> - type to which we want to convert the contract + * + * @author Marcin Grzejszczak + * @since 1.1.0 + */ +interface ContractConverter<T> { + + /** + * Should this file be accepted by the converter. Can use the file extension + * to check if the conversion is possible. + * + * @param file - file to be considered for conversion + * @return - {@code true} if the given implementation can convert the file + */ + boolean isAccepted(File file) + + /** + * Converts the given {@link File} to its {@link Contract} representation + * + * @param file - file to convert + * @return - {@link Contract} representation of the file + */ + Collection<Contract> convertFrom(File file) + + /** + * Converts the given {@link Contract} to a {@link T} representation + * + * @param contract - the parsed contract + * @return - {@link T} the type to which we do the conversion + */ + T convertTo(Collection<Contract> contract) +} +Your implementation must define the condition on which it should start the +conversion. Also, you must define how to perform that conversion in both directions. + +Once you create your implementation, you must create a +/META-INF/spring.factories file in which you provide the fully qualified name of your +implementation. + +The following example shows a typical spring.factories file: +org.springframework.cloud.contract.spec.ContractConverter=\ +org.springframework.cloud.contract.verifier.converter.YamlContractConverter +
+Pact Converter +Spring Cloud Contract includes support for Pact representation of +contracts. Instead of using the Groovy DSL, you can use Pact files. In this section, we +present how to add Pact support for your project. +
+
+Pact Contract +Consider following example of a Pact contract, which is a file under the +src/test/resources/contracts folder. +{ + "provider": { + "name": "Provider" + }, + "consumer": { + "name": "Consumer" + }, + "interactions": [ + { + "description": "", + "request": { + "method": "PUT", + "path": "/fraudcheck", + "headers": { + "Content-Type": "application/vnd.fraud.v1+json" + }, + "body": { + "clientId": "1234567890", + "loanAmount": 99999 + }, + "matchingRules": { + "$.body.clientId": { + "match": "regex", + "regex": "[0-9]{10}" + } + } + }, + "response": { + "status": 200, + "headers": { + "Content-Type": "application/vnd.fraud.v1+json;charset=UTF-8" + }, + "body": { + "fraudCheckStatus": "FRAUD", + "rejectionReason": "Amount too high" + }, + "matchingRules": { + "$.body.fraudCheckStatus": { + "match": "regex", + "regex": "FRAUD" + } + } + } + } + ], + "metadata": { + "pact-specification": { + "version": "2.0.0" + }, + "pact-jvm": { + "version": "2.4.18" + } + } +} +The remainder of this section about using Pact refers to the preceding file. +
+
+Pact for Producers +On the producer side, you mustadd two additional dependencies to your plugin +configuration. One is the Spring Cloud Contract Pact support, and the other represents +the current Pact version that you use. + +Maven + +<plugin> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-maven-plugin</artifactId> + <version>${spring-cloud-contract.version}</version> + <extensions>true</extensions> + <configuration> + <packageWithBaseClasses>com.example.fraud</packageWithBaseClasses> + </configuration> + <dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-spec-pact</artifactId> + <version>${spring-cloud-contract.version}</version> + </dependency> + <dependency> + <groupId>au.com.dius</groupId> + <artifactId>pact-jvm-model</artifactId> + <version>2.4.18</version> + </dependency> + </dependencies> +</plugin> + + + +Gradle + +classpath "org.springframework.cloud:spring-cloud-contract-spec-pact:${findProperty('verifierVersion') ?: verifierVersion}" +classpath 'au.com.dius:pact-jvm-model:2.4.18' + + +When you execute the build of your application, a test will be generated. The generated +test might be as follows: +@Test +public void validate_shouldMarkClientAsFraud() throws Exception { + // given: + MockMvcRequestSpecification request = given() + .header("Content-Type", "application/vnd.fraud.v1+json") + .body("{\"clientId\":\"1234567890\",\"loanAmount\":99999}"); + + // when: + ResponseOptions response = given().spec(request) + .put("/fraudcheck"); + + // then: + assertThat(response.statusCode()).isEqualTo(200); + assertThat(response.header("Content-Type")).isEqualTo("application/vnd.fraud.v1+json;charset=UTF-8"); + // and: + DocumentContext parsedJson = JsonPath.parse(response.getBody().asString()); + assertThatJson(parsedJson).field("rejectionReason").isEqualTo("Amount too high"); + // and: + assertThat(parsedJson.read("$.fraudCheckStatus", String.class)).matches("FRAUD"); +} +The corresponding generated stub might be as follows: +{ + "uuid" : "996ae5ae-6834-4db6-8fac-358ca187ab62", + "request" : { + "url" : "/fraudcheck", + "method" : "PUT", + "headers" : { + "Content-Type" : { + "equalTo" : "application/vnd.fraud.v1+json" + } + }, + "bodyPatterns" : [ { + "matchesJsonPath" : "$[?(@.loanAmount == 99999)]" + }, { + "matchesJsonPath" : "$[?(@.clientId =~ /([0-9]{10})/)]" + } ] + }, + "response" : { + "status" : 200, + "body" : "{\"fraudCheckStatus\":\"FRAUD\",\"rejectionReason\":\"Amount too high\"}", + "headers" : { + "Content-Type" : "application/vnd.fraud.v1+json;charset=UTF-8" + } + } +} +
+
+Pact for Consumers +On the producer side, you must add two additional dependencies to your project +dependencies. One is the Spring Cloud Contract Pact support, and the other represents the +current Pact version that you use. + +Maven + +<dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-contract-spec-pact</artifactId> + <scope>test</scope> +</dependency> +<dependency> + <groupId>au.com.dius</groupId> + <artifactId>pact-jvm-model</artifactId> + <version>2.4.18</version> + <scope>test</scope> +</dependency> + + + +Gradle + +testCompile "org.springframework.cloud:spring-cloud-contract-spec-pact" +testCompile 'au.com.dius:pact-jvm-model:2.4.18' + + +
+
+
+Using the Custom Test Generator +If you want to generate tests for languages other than Java or you are not happy with the +way the verifier builds Java tests, you can register your own implementation. +The SingleTestGenerator interface lets you register your own implementation. The +following code listing shows the SingleTestGenerator interface: +package org.springframework.cloud.contract.verifier.builder + +import org.springframework.cloud.contract.verifier.config.ContractVerifierConfigProperties +import org.springframework.cloud.contract.verifier.file.ContractMetadata +/** + * Builds a single test. + * + * @since 1.1.0 + */ +interface SingleTestGenerator { + + /** + * Creates contents of a single test class in which all test scenarios from + * the contract metadata should be placed. + * + * @param properties - properties passed to the plugin + * @param listOfFiles - list of parsed contracts with additional metadata + * @param className - the name of the generated test class + * @param classPackage - the name of the package in which the test class should be stored + * @param includedDirectoryRelativePath - relative path to the included directory + * @return contents of a single test class + */ + String buildClass(ContractVerifierConfigProperties properties, Collection<ContractMetadata> listOfFiles, + String className, String classPackage, String includedDirectoryRelativePath) + + /** + * Extension that should be appended to the generated test class. E.g. {@code .java} or {@code .php} + * + * @param properties - properties passed to the plugin + */ + String fileExtension(ContractVerifierConfigProperties properties) +} +Again, you must provide a spring.factories file, such as the one shown in the following +example: +org.springframework.cloud.contract.verifier.builder.SingleTestGenerator=/ +com.example.MyGenerator +
+
+Using the Custom Stub Generator +If you want to generate stubs for stub servers other than WireMock, you can plug in your +own implementation of the StubGenerator interface. The following code listing shows the +StubGenerator interface: +package org.springframework.cloud.contract.verifier.converter + +import groovy.transform.CompileStatic +import org.springframework.cloud.contract.spec.Contract +import org.springframework.cloud.contract.verifier.file.ContractMetadata + +/** + * Converts contracts into their stub representation. + * + * @since 1.1.0 + */ +@CompileStatic +interface StubGenerator { + + /** + * Returns {@code true} if the converter can handle the file to convert it into a stub. + */ + boolean canHandleFileName(String fileName) + + /** + * Returns the collection of converted contracts into stubs. One contract can + * result in multiple stubs. + */ + Map<Contract, String> convertContents(String rootName, ContractMetadata content) + + /** + * Returns the name of the converted stub file. If you have multiple contracts + * in a single file then a prefix will be added to the generated file. If you + * provide the {@link Contract#name} field then that field will override the + * generated file name. + * + * Example: name of file with 2 contracts is {@code foo.groovy}, it will be + * converted by the implementation to {@code foo.json}. The recursive file + * converter will create two files {@code 0_foo.json} and {@code 1_foo.json} + */ + String generateOutputFileNameForInput(String inputFileName) +} +Again, you must provide a spring.factories file, such as the one shown in the following +example: +# Stub converters +org.springframework.cloud.contract.verifier.converter.StubGenerator=\ +org.springframework.cloud.contract.verifier.wiremock.DslToWireMockClientConverter +The default implementation is the WireMock stub generation. + +You can provide multiple stub generator implementations. For example, from a single +DSL, you can produce both WireMock stubs and Pact files. + +
+
+Using the Custom Stub Runner +If you decide to use a custom stub generation, you also need a custom way of running +stubs with your different stub provider. +Assume that you use Moco to build your stubs and that +you have written a stub generator and placed your stubs in a JAR file. +In order for Stub Runner to know how to run your stubs, you have to define a custom +HTTP Stub server implementation, which might resemble the following example: +package org.springframework.cloud.contract.stubrunner.provider.moco + +import com.github.dreamhead.moco.bootstrap.arg.HttpArgs +import com.github.dreamhead.moco.runner.JsonRunner +import com.github.dreamhead.moco.runner.RunnerSetting +import groovy.util.logging.Slf4j +import org.springframework.cloud.contract.stubrunner.HttpServerStub +import org.springframework.util.SocketUtils + +@Slf4j +class MocoHttpServerStub implements HttpServerStub { + + private boolean started + private JsonRunner runner + private int port + + @Override + int port() { + if (!isRunning()) { + return -1 + } + return port + } + + @Override + boolean isRunning() { + return started + } + + @Override + HttpServerStub start() { + return start(SocketUtils.findAvailableTcpPort()) + } + + @Override + HttpServerStub start(int port) { + this.port = port + return this + } + + @Override + HttpServerStub stop() { + if (!isRunning()) { + return this + } + this.runner.stop() + return this + } + + @Override + HttpServerStub registerMappings(Collection<File> stubFiles) { + List<RunnerSetting> settings = stubFiles.findAll { it.name.endsWith("json") } + .collect { + log.info("Trying to parse [{}]", it.name) + try { + return RunnerSetting.aRunnerSetting().withStream(it.newInputStream()).build() + } catch (Exception e) { + log.warn("Exception occurred while trying to parse file [{}]", it.name, e) + return null + } + }.findAll { it } + this.runner = JsonRunner.newJsonRunnerWithSetting(settings, + HttpArgs.httpArgs().withPort(this.port).build()) + this.runner.run() + this.started = true + return this + } + + @Override + String registeredMappings() { + return "" + } + + @Override + boolean isAccepted(File file) { + return file.name.endsWith(".json") + } +} +Then, you can register it in your spring.factories file, as shown in the following +example: +org.springframework.cloud.contract.stubrunner.HttpServerStub=\ +org.springframework.cloud.contract.stubrunner.provider.moco.MocoHttpServerStub +Now you can run stubs with Moco. + +If you do not provide any implementation, then the default (WireMock) +implementation is used. If you provide more than one, the first one on the list is used. + +
+
+Using the Custom Stub Downloader +You can customize the way your stubs are downloaded by creating an implementation of the +StubDownloaderBuilder interface, as shown in the following example: +package com.example; + +class CustomStubDownloaderBuilder implements StubDownloaderBuilder { + + @Override + public StubDownloader build(final StubRunnerOptions stubRunnerOptions) { + return new StubDownloader() { + @Override + public Map.Entry<StubConfiguration, File> downloadAndUnpackStubJar( + StubConfiguration config) { + File unpackedStubs = retrieveStubs(); + return new AbstractMap.SimpleEntry<>( + new StubConfiguration(config.getGroupId(), config.getArtifactId(), version, + config.getClassifier()), unpackedStubs); + } + + File retrieveStubs() { + // here goes your custom logic to provide a folder where all the stubs reside + } +} +Then you can register it in your spring.factories file, as shown in the following +example: +# Example of a custom Stub Downloader Provider +org.springframework.cloud.contract.stubrunner.StubDownloaderBuilder=\ +com.example.CustomStubDownloaderBuilder +Now you can pick a folder with the source of your stubs. + +If you do not provide any implementation, then the default is used. +If you use the repositoryRoot property or the workOffline flag, then an Aether-based +implementation that downloads stubs from a remote repository is used. If you do not +provide these values, the ClasspathStubProvider (which will scan the classpath) is +used. If you provide more than one, then the first one on the list is used. + +
+ + +Spring Cloud Contract WireMock +The Spring Cloud Contract WireMock modules let you use WireMock in a +Spring Boot application. Check out the +samples +for more details. +If you have a Spring Boot application that uses Tomcat as an embedded server (which is +the default with spring-boot-starter-web), you can add +spring-cloud-starter-contract-stub-runner to your classpath and add @AutoConfigureWireMock in +order to be able to use Wiremock in your tests. Wiremock runs as a stub server and you +can register stub behavior using a Java API or via static JSON declarations as part of +your test. The following code shows an example: +@RunWith(SpringRunner.class) +@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT) +@AutoConfigureWireMock(port = 0) +public class WiremockForDocsTests { + // A service that calls out over HTTP + @Autowired private Service service; + + // Using the WireMock APIs in the normal way: + @Test + public void contextLoads() throws Exception { + // Stubbing WireMock + stubFor(get(urlEqualTo("/resource")) + .willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!"))); + // We're asserting if WireMock responded properly + assertThat(this.service.go()).isEqualTo("Hello World!"); + } + +} +To start the stub server on a different port use (for example), +@AutoConfigureWireMock(port=9999). For a random port, use a value of 0. The stub +server port can be bound in the test application context with the "wiremock.server.port" +property. Using @AutoConfigureWireMock adds a bean of type WiremockConfiguration to +your test application context, where it will be cached in between methods and classes +having the same context, the same as for Spring integration tests. +
+Registering Stubs Automatically +If you use @AutoConfigureWireMock, it registers WireMock JSON stubs from the file +system or classpath (by default, from file:src/test/resources/mappings). You can +customize the locations using the stubs attribute in the annotation, which can be an +Ant-style resource pattern or a directory. In the case of a directory, */.json is +appended. The following code shows an example: +@RunWith(SpringRunner.class) +@SpringBootTest +@AutoConfigureWireMock(stubs="classpath:/stubs") +public class WiremockImportApplicationTests { + + @Autowired + private Service service; + + @Test + public void contextLoads() throws Exception { + assertThat(this.service.go()).isEqualTo("Hello World!"); + } + +} + +Actually, WireMock always loads mappings from src/test/resources/mappings as +well as the custom locations in the stubs attribute. To change this behavior, you can +also specify a files root as described in the next section of this document. + +
+
+Using Files to Specify the Stub Bodies +WireMock can read response bodies from files on the classpath or the file system. In that +case, you can see in the JSON DSL that the response has a bodyFileName instead of a +(literal) body. The files are resolved relative to a root directory (by default, +src/test/resources/__files). To customize this location you can set the files +attribute in the @AutoConfigureWireMock annotation to the location of the parent +directory (in other words, __files is a subdirectory). You can use Spring resource +notation to refer to file:…​ or classpath:…​ locations. Generic URLs are not +supported. A list of values can be given, in which case WireMock resolves the first file +that exists when it needs to find a response body. + +When you configure the files root, it also affects the +automatic loading of stubs, because they come from the root location +in a subdirectory called "mappings". The value of files has no +effect on the stubs loaded explicitly from the stubs attribute. + +
+
+Alternative: Using JUnit Rules +For a more conventional WireMock experience, you can use JUnit @Rules to start and stop +the server. To do so, use the WireMockSpring convenience class to obtain an Options +instance, as shown in the following example: +@RunWith(SpringRunner.class) +@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT) +public class WiremockForDocsClassRuleTests { + + // Start WireMock on some dynamic port + // for some reason `dynamicPort()` is not working properly + @ClassRule + public static WireMockClassRule wiremock = new WireMockClassRule( + WireMockSpring.options().dynamicPort()); + // A service that calls out over HTTP to localhost:${wiremock.port} + @Autowired + private Service service; + + // Using the WireMock APIs in the normal way: + @Test + public void contextLoads() throws Exception { + // Stubbing WireMock + wiremock.stubFor(get(urlEqualTo("/resource")) + .willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!"))); + // We're asserting if WireMock responded properly + assertThat(this.service.go()).isEqualTo("Hello World!"); + } + +} +The @ClassRule means that the server shuts down after all the methods in this class +have been run. +
+
+Relaxed SSL Validation for Rest Template +WireMock lets you stub a "secure" server with an "https" URL protocol. If your +application wants to contact that stub server in an integration test, it will find that +the SSL certificates are not valid (the usual problem with self-installed certificates). +The best option is often to re-configure the client to use "http". If that’s not an +option, you can ask Spring to configure an HTTP client that ignores SSL validation errors +(do so only for tests, of course). +To make this work with minimum fuss, you need to be using the Spring Boot +RestTemplateBuilder in your app, as shown in the following example: +@Bean +public RestTemplate restTemplate(RestTemplateBuilder builder) { + return builder.build(); +} +You need RestTemplateBuilder because the builder is passed through callbacks to +initialize it, so the SSL validation can be set up in the client at that point. This +happens automatically in your test if you are using the @AutoConfigureWireMock +annotation or the stub runner. If you use the JUnit @Rule approach, you need to add the +@AutoConfigureHttpClient annotation as well, as shown in the following example: +@RunWith(SpringRunner.class) +@SpringBootTest("app.baseUrl=https://localhost:6443") +@AutoConfigureHttpClient +public class WiremockHttpsServerApplicationTests { + + @ClassRule + public static WireMockClassRule wiremock = new WireMockClassRule( + WireMockSpring.options().httpsPort(6443)); +... +} +If you are using spring-boot-starter-test, you have the Apache HTTP client on the +classpath and it is selected by the RestTemplateBuilder and configured to ignore SSL +errors. If you use the default java.net client, you do not need the annotation (but it +won’t do any harm). There is no support currently for other clients, but it may be added +in future releases. +
+
+WireMock and Spring MVC Mocks +Spring Cloud Contract provides a convenience class that can load JSON WireMock stubs into +a Spring MockRestServiceServer. The following code shows an example: +@RunWith(SpringRunner.class) +@SpringBootTest(webEnvironment = WebEnvironment.NONE) +public class WiremockForDocsMockServerApplicationTests { + + @Autowired + private RestTemplate restTemplate; + + @Autowired + private Service service; + + @Test + public void contextLoads() throws Exception { + // will read stubs classpath + MockRestServiceServer server = WireMockRestServiceServer.with(this.restTemplate) + .baseUrl("https://example.org").stubs("classpath:/stubs/resource.json") + .build(); + // We're asserting if WireMock responded properly + assertThat(this.service.go()).isEqualTo("Hello World"); + server.verify(); + } +} +The baseUrl value is prepended to all mock calls, and the stubs() method takes a stub +path resource pattern as an argument. In the preceding example, the stub defined at +/stubs/resource.json is loaded into the mock server. If the RestTemplate is asked to +visit https://example.org/, it gets the responses as being declared at that URL. More +than one stub pattern can be specified, and each one can be a directory (for a recursive +list of all ".json"), a fixed filename (as in the example above), or an Ant-style +pattern. The JSON format is the normal WireMock format, which you can read about in the +WireMock website. +Currently, the Spring Cloud Contract Verifier supports Tomcat, Jetty, and Undertow as +Spring Boot embedded servers, and Wiremock itself has "native" support for a particular +version of Jetty (currently 9.2). To use the native Jetty, you need to add the native +Wiremock dependencies and exclude the Spring Boot container (if there is one). +
+
+Customization of WireMock configuration +You can register a bean of org.springframework.cloud.contract.wiremock.WireMockConfigurationCustomizer type +in order to customize the WireMock configuration (e.g. add custom transformers). +Example: + @Bean WireMockConfigurationCustomizer optionsCustomizer() { + return new WireMockConfigurationCustomizer() { + @Override public void customize(WireMockConfiguration options) { +// perform your customization here + } + }; + } +
+
+Generating Stubs using REST Docs +Spring REST Docs can be used to generate +documentation (for example in Asciidoctor format) for an HTTP API with Spring MockMvc or +Rest Assured. At the same time that you generate documentation for your API, you can also +generate WireMock stubs by using Spring Cloud Contract WireMock. To do so, write your +normal REST Docs test cases and use @AutoConfigureRestDocs to have stubs be +automatically generated in the REST Docs output directory. The following code shows an +example: +@RunWith(SpringRunner.class) +@SpringBootTest +@AutoConfigureRestDocs(outputDir = "target/snippets") +@AutoConfigureMockMvc +public class ApplicationTests { + + @Autowired + private MockMvc mockMvc; + + @Test + public void contextLoads() throws Exception { + mockMvc.perform(get("/resource")) + .andExpect(content().string("Hello World")) + .andDo(document("resource")); + } +} +This test generates a WireMock stub at "target/snippets/stubs/resource.json". It matches +all GET requests to the "/resource" path. +Without any additional configuration, this tests creates a stub with a request matcher +for the HTTP method and all headers except "host" and "content-length". To match the +request more precisely (for example, to match the body of a POST or PUT), we need to +explicitly create a request matcher. Doing so has two effects: + + +Creating a stub that matches only in the way you specify. + + +Asserting that the request in the test case also matches the same conditions. + + +The main entry point for this feature is WireMockRestDocs.verify(), which can be used +as a substitute for the document() convenience method, as shown in the following +example: +@RunWith(SpringRunner.class) +@SpringBootTest +@AutoConfigureRestDocs(outputDir = "target/snippets") +@AutoConfigureMockMvc +public class ApplicationTests { + + @Autowired + private MockMvc mockMvc; + + @Test + public void contextLoads() throws Exception { + mockMvc.perform(post("/resource") + .content("{\"id\":\"123456\",\"message\":\"Hello World\"}")) + .andExpect(status().isOk()) + .andDo(verify().jsonPath("$.id") + .stub("resource")); + } +} +This contract specifies that any valid POST with an "id" field receives the response +defined in this test. You can chain together calls to .jsonPath() to add additional +matchers. If JSON Path is unfamiliar, The JayWay +documentation can help you get up to speed. +Instead of the jsonPath and contentType convenience methods, you can also use the +WireMock APIs to verify that the request matches the created stub, as shown in the +following example: +@Test +public void contextLoads() throws Exception { + mockMvc.perform(post("/resource") + .content("{\"id\":\"123456\",\"message\":\"Hello World\"}")) + .andExpect(status().isOk()) + .andDo(verify() + .wiremock(WireMock.post( + urlPathEquals("/resource")) + .withRequestBody(matchingJsonPath("$.id")) + .stub("post-resource")); +} +The WireMock API is rich. You can match headers, query parameters, and request body by +regex as well as by JSON path. These features can be used to create stubs with a wider +range of parameters. The above example generates a stub resembling the following example: + +post-resource.json + +{ + "request" : { + "url" : "/resource", + "method" : "POST", + "bodyPatterns" : [ { + "matchesJsonPath" : "$.id" + }] + }, + "response" : { + "status" : 200, + "body" : "Hello World", + "headers" : { + "X-Application-Context" : "application:-1", + "Content-Type" : "text/plain" + } + } +} + + + +You can use either the wiremock() method or the jsonPath() and contentType() +methods to create request matchers, but you can’t use both approaches. + +On the consumer side, you can make the resource.json generated earlier in this section +available on the classpath (by +publishing +stubs as JARs, for example). After that, you can create a stub using WireMock in a +number of different ways, including by using +@AutoConfigureWireMock(stubs="classpath:resource.json"), as described earlier in this +document. +
+
+Generating Contracts by Using REST Docs +You can also generate Spring Cloud Contract DSL files and documentation with Spring REST +Docs. If you do so in combination with Spring Cloud WireMock, you get both the contracts +and the stubs. +Why would you want to use this feature? Some people in the community asked questions +about a situation in which they would like to move to DSL-based contract definition, +but they already have a lot of Spring MVC tests. Using this feature lets you generate +the contract files that you can later modify and move to folders (defined in your +configuration) so that the plugin finds them. + +You might wonder why this functionality is in the WireMock module. The functionality +is there because it makes sense to generate both the contracts and the stubs. + +Consider the following test: + this.mockMvc.perform(post("/foo") + .accept(MediaType.APPLICATION_PDF) + .accept(MediaType.APPLICATION_JSON) + .contentType(MediaType.APPLICATION_JSON) + .content("{\"foo\": 23, \"bar\" : \"baz\" }")) + .andExpect(status().isOk()) + .andExpect(content().string("bar")) + // first WireMock + .andDo(WireMockRestDocs.verify() + .jsonPath("$[?(@.foo >= 20)]") + .jsonPath("$[?(@.bar in ['baz','bazz','bazzz'])]") + .contentType(MediaType.valueOf("application/json")) + .stub("shouldGrantABeerIfOldEnough")) + // then Contract DSL documentation + .andDo(document("index", SpringCloudContractRestDocs.dslContract())); +The preceding test creates the stub presented in the previous section, generating both +the contract and a documentation file. +The contract is called index.groovy and might look like the following example: +import org.springframework.cloud.contract.spec.Contract + +Contract.make { + request { + method 'POST' + url '/foo' + body(''' + {"foo": 23 } + ''') + headers { + header('''Accept''', '''application/json''') + header('''Content-Type''', '''application/json''') + } + } + response { + status 200 + body(''' + bar + ''') + headers { + header('''Content-Type''', '''application/json;charset=UTF-8''') + header('''Content-Length''', '''3''') + } + testMatchers { + jsonPath('$[?(@.foo >= 20)]', byType()) + } + } +} +The generated document (formatted in Asciidoc in this case) contains a formatted +contract. The location of this file would be index/dsl-contract.adoc. +
+ + +Migrations +This section covers migrating from one version of Spring Cloud Contract Verifier to the +next version. It covers the following versions upgrade paths: +
+1.0.x → 1.1.x +This section covers upgrading from version 1.0 to version 1.1. +
+New structure of generated stubs +In 1.1.x we have introduced a change to the structure of generated stubs. If you have +been using the @AutoConfigureWireMock notation to use the stubs from the classpath, +it no longer works. The following example shows how the @AutoConfigureWireMock notation +used to work: +@AutoConfigureWireMock(stubs = "classpath:/customer-stubs/mappings", port = 8084) +You must either change the location of the stubs to: +classpath:…​/META-INF/groupId/artifactId/version/mappings or use the new +classpath-based @AutoConfigureStubRunner, as shown in the following example: +@AutoConfigureWireMock(stubs = "classpath:customer-stubs/META-INF/travel.components/customer-contract/1.0.2-SNAPSHOT/mappings/", port = 8084) +If you do not want to use @AutoConfigureStubRunner and you want to remain with the old +structure, set your plugin tasks accordingly. The following example would work for the +structure presented in the previous snippet. + +Maven + +<!-- start of pom.xml --> + +<properties> + <!-- we don't want the verifier to do a jar for us --> + <spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip> +</properties> + +<!-- ... --> + +<!-- You need to set up the assembly plugin --> +<build> + <plugins> + <plugin> + <groupId>org.apache.maven.plugins</groupId> + <artifactId>maven-assembly-plugin</artifactId> + <executions> + <execution> + <id>stub</id> + <phase>prepare-package</phase> + <goals> + <goal>single</goal> + </goals> + <inherited>false</inherited> + <configuration> + <attach>true</attach> + <descriptor>$../../../../src/assembly/stub.xml</descriptor> + </configuration> + </execution> + </executions> + </plugin> + </plugins> +</build> +<!-- end of pom.xml --> + +<!-- start of stub.xml--> + +<assembly + xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3" + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd"> + <id>stubs</id> + <formats> + <format>jar</format> + </formats> + <includeBaseDirectory>false</includeBaseDirectory> + <fileSets> + <fileSet> + <directory>${project.build.directory}/snippets/stubs</directory> + <outputDirectory>customer-stubs/mappings</outputDirectory> + <includes> + <include>**/*</include> + </includes> + </fileSet> + <fileSet> + <directory>$../../../../src/test/resources/contracts</directory> + <outputDirectory>customer-stubs/contracts</outputDirectory> + <includes> + <include>**/*.groovy</include> + </includes> + </fileSet> + </fileSets> +</assembly> + +<!-- end of stub.xml--> + + + +Gradle + +task copyStubs(type: Copy, dependsOn: 'generateWireMockClientStubs') { +// Preserve directory structure from 1.0.X of spring-cloud-contract + from "${project.buildDir}/resources/main/customer-stubs/META-INF/${project.group}/${project.name}/${project.version}" + into "${project.buildDir}/resources/main/customer-stubs" +} + + +
+
+
+1.1.x → 1.2.x +This section covers upgrading from version 1.1 to version 1.2. +
+Custom <literal>HttpServerStub</literal> +HttpServerStub includes a method that was not in version 1.1. The method is +String registeredMappings() If you have classes that implement HttpServerStub, you +now have to implement the registeredMappings() method. It should return a String +representing all mappings available in a single HttpServerStub. +See issue 355 for more +detail. +
+
+New packages for generated tests +The flow for setting the generated tests package name will look like this: + + +Set basePackageForTests + + +If basePackageForTests was not set, pick the package from baseClassForTests + + +If baseClassForTests was not set, pick packageWithBaseClasses + + +If nothing got set, pick the default value: +org.springframework.cloud.contract.verifier.tests + + +See issue 260 for more +detail. +
+
+New Methods in TemplateProcessor +In order to add support for fromRequest.path, the following methods had to be added to the +TemplateProcessor interface: + + +path() + + +path(int index) + + +See issue 388 for more +detail. +
+
+RestAssured 3.0 +Rest Assured, used in the generated test classes, got bumped to 3.0. If +you manually set versions of Spring Cloud Contract and the release train +you might see the following exception: +Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:testCompile (default-testCompile) on project some-project: Compilation failure: Compilation failure: +[ERROR] /some/path/SomeClass.java:[4,39] package com.jayway.restassured.response does not exist +This exception will occur due to the fact that the tests got generated with +an old version of plugin and at test execution time you have an incompatible +version of the release train (and vice versa). +Done via issue 267 +
+
+ + +Links +The following links may be helpful when working with Spring Cloud Contract Verifier: + + +Spring Cloud Contract Github +Repository + + +Spring Cloud +Contract Samples + + +Spring Cloud +Contract Documentation + + +Accurest +Legacy Documentation + + +Spring +Cloud Contract Stub Runner Documentation + + +Spring +Cloud Contract Stub Runner Messaging Documentation + + +Spring Cloud Contract Gitter + + +Spring +Cloud Contract Maven Plugin + + +Spring Cloud Contract WJUG Presentation by +Marcin Grzejszczak + + + + + +Spring Cloud Vault + +© 2016-2017 The original authors. + +Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically. + +Spring Cloud Vault Config provides client-side support for externalized configuration in a distributed system. With HashiCorp’s Vault you have a central place to manage external secret properties for applications across all environments. Vault can manage static and dynamic secrets such as username/password for remote applications/resources and provide credentials for external services such as MySQL, PostgreSQL, Apache Cassandra, MongoDB, Consul, AWS and more. + + +Quick Start +Prerequisites +To get started with Vault and this guide you need a +*NIX-like operating systems that provides: + + +wget, openssl and unzip + + +at least Java 7 and a properly configured JAVA_HOME environment variable + + +Install Vault +$ src/test/bash/install_vault.sh +Create SSL certificates for Vault +$ src/test/bash/create_certificates.sh + +create_certificates.sh creates certificates in work/ca and a JKS truststore work/keystore.jks. If you want to run Spring Cloud Vault using this quickstart guide you need to configure the truststore the spring.cloud.vault.ssl.trust-store property to file:work/keystore.jks. + +Start Vault server +$ src/test/bash/local_run_vault.sh +Vault is started listening on 0.0.0.0:8200 using the inmem storage and +https. +Vault is sealed and not initialized when starting up. + +If you want to run tests, leave Vault uninitialized. The tests will +initialize Vault and create a root token 00000000-0000-0000-0000-000000000000. + +If you want to use Vault for your application or give it a try then you need to initialize it first. +$ export VAULT_ADDR="https://localhost:8200" +$ export VAULT_SKIP_VERIFY=true # Don't do this for production +$ vault init +You should see something like: +Key 1: 7149c6a2e16b8833f6eb1e76df03e47f6113a3288b3093faf5033d44f0e70fe701 +Key 2: 901c534c7988c18c20435a85213c683bdcf0efcd82e38e2893779f152978c18c02 +Key 3: 03ff3948575b1165a20c20ee7c3e6edf04f4cdbe0e82dbff5be49c63f98bc03a03 +Key 4: 216ae5cc3ddaf93ceb8e1d15bb9fc3176653f5b738f5f3d1ee00cd7dccbe926e04 +Key 5: b2898fc8130929d569c1677ee69dc5f3be57d7c4b494a6062693ce0b1c4d93d805 +Initial Root Token: 19aefa97-cccc-bbbb-aaaa-225940e63d76 + +Vault initialized with 5 keys and a key threshold of 3. Please +securely distribute the above keys. When the Vault is re-sealed, +restarted, or stopped, you must provide at least 3 of these keys +to unseal it again. + +Vault does not store the master key. Without at least 3 keys, +your Vault will remain permanently sealed. +Vault will initialize and return a set of unsealing keys and the root token. +Pick 3 keys and unseal Vault. Store the Vault token in the VAULT_TOKEN + environment variable. +$ vault unseal (Key 1) +$ vault unseal (Key 2) +$ vault unseal (Key 3) +$ export VAULT_TOKEN=(Root token) +# Required to run Spring Cloud Vault tests after manual initialization +$ vault token-create -id="00000000-0000-0000-0000-000000000000" -policy="root" +Spring Cloud Vault accesses different resources. By default, the secret +backend is enabled which accesses secret config settings via JSON endpoints. +The HTTP service has resources in the form: +/secret/{application}/{profile} +/secret/{application} +/secret/{defaultContext}/{profile} +/secret/{defaultContext} +where the "application" is injected as the spring.application.name in the +SpringApplication (i.e. what is normally "application" in a regular +Spring Boot app), "profile" is an active profile (or comma-separated +list of properties). Properties retrieved from Vault will be used "as-is" +without further prefixing of the property names. + + +Client Side Usage +To use these features in an application, just build it as a Spring +Boot application that depends on spring-cloud-vault-config (e.g. see +the test cases). Example Maven configuration: + +pom.xml +<parent> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-starter-parent</artifactId> + <version>1.5.4.RELEASE</version> + <relativePath /> <!-- lookup parent from repository --> +</parent> + +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-starter-vault-config</artifactId> + <version>1.3.8.RELEASE</version> + </dependency> + <dependency> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-starter-test</artifactId> + <scope>test</scope> + </dependency> +</dependencies> + +<build> + <plugins> + <plugin> + <groupId>org.springframework.boot</groupId> + <artifactId>spring-boot-maven-plugin</artifactId> + </plugin> + </plugins> +</build> + +<!-- repositories also needed for snapshots and milestones --> + +Then you can create a standard Spring Boot application, like this simple HTTP server: + +@SpringBootApplication +@RestController +public class Application { + + @RequestMapping("/") + public String home() { + return "Hello World!"; + } + + public static void main(String[] args) { + SpringApplication.run(Application.class, args); + } +} + +When it runs it will pick up the external configuration from the +default local Vault server on port 8200 if it is running. To modify +the startup behavior you can change the location of the Vault server +using bootstrap.properties (like application.properties but for +the bootstrap phase of an application context), e.g. + +bootstrap.yml +spring.cloud.vault: + host: localhost + port: 8200 + scheme: https + uri: https://localhost:8200 + connection-timeout: 5000 + read-timeout: 15000 + config: + order: -10 + + + +host sets the hostname of the Vault host. The host name will be used +for SSL certificate validation + + +port sets the Vault port + + +scheme setting the scheme to http will use plain HTTP. +Supported schemes are http and https. + + +uri configure the Vault endpoint with an URI. Takes precedence over host/port/scheme configuration + + +connection-timeout sets the connection timeout in milliseconds + + +read-timeout sets the read timeout in milliseconds + + +config.order sets the order for the property source + + +Enabling further integrations requires additional dependencies and +configuration. Depending on how you have set up Vault you might need +additional configuration like +SSL and +authentication. +If the application imports the spring-boot-starter-actuator project, the +status of the vault server will be available via the /health endpoint. +The vault health indicator can be enabled or disabled through the +property health.vault.enabled (default true). +
+Authentication +Vault requires an authentication mechanism to authorize client requests. +Spring Cloud Vault supports multiple authentication mechanisms to authenticate applications with Vault. +For a quickstart, use the root token printed by the Vault initialization. + +bootstrap.yml +spring.cloud.vault: + token: 19aefa97-cccc-bbbb-aaaa-225940e63d76 + + +Consider carefully your security requirements. Static token authentication is fine if you want quickly get started with Vault, but a static token is not protected any further. Any disclosure to unintended parties allows Vault use with the associated token roles. + +
+ + +Authentication methods +Different organizations have different requirements for security +and authentication. Vault reflects that need by shipping multiple authentication +methods. Spring Cloud Vault supports token and AppId authentication. +
+Token authentication +Tokens are the core method for authentication within Vault. +Token authentication requires a static token to be provided using the +Bootstrap Application Context. + +Token authentication is the default authentication method. +If a token is disclosed an unintended party gains access to Vault and +can access secrets for the intended client. + + +bootstrap.yml +spring.cloud.vault: + authentication: TOKEN + token: 00000000-0000-0000-0000-000000000000 + + + +authentication setting this value to TOKEN selects the Token +authentication method + + +token sets the static token to use + + +See also: Vault Documentation: Tokens +
+
+AppId authentication +Vault supports AppId +authentication that consists of two hard to guess tokens. The AppId +defaults to spring.application.name that is statically configured. +The second token is the UserId which is a part determined by the application, +usually related to the runtime environment. IP address, Mac address or a +Docker container name are good examples. Spring Cloud Vault Config supports +IP address, Mac address and static UserId’s (e.g. supplied via System properties). +The IP and Mac address are represented as Hex-encoded SHA256 hash. +IP address-based UserId’s use the local host’s IP address. + +bootstrap.yml using SHA256 IP-Address UserId’s +spring.cloud.vault: + authentication: APPID + app-id: + user-id: IP_ADDRESS + + + +authentication setting this value to APPID selects the AppId +authentication method + + +app-id-path sets the path of the AppId mount to use + + +user-id sets the UserId method. Possible values are IP_ADDRESS, +MAC_ADDRESS or a class name implementing a custom AppIdUserIdMechanism + + +The corresponding command to generate the IP address UserId from a command line is: +$ echo -n 192.168.99.1 | sha256sum + +Including the line break of echo leads to a different hash value +so make sure to include the -n flag. + +Mac address-based UserId’s obtain their network device from the +localhost-bound device. The configuration also allows specifying +a network-interface hint to pick the right device. The value of +network-interface is optional and can be either an interface +name or interface index (0-based). + +bootstrap.yml using SHA256 Mac-Address UserId’s +spring.cloud.vault: + authentication: APPID + app-id: + user-id: MAC_ADDRESS + network-interface: eth0 + + + +network-interface sets network interface to obtain the physical address + + +The corresponding command to generate the IP address UserId from a command line is: +$ echo -n 0AFEDE1234AC | sha256sum + +The Mac address is specified uppercase and without colons. +Including the line break of echo leads to a different hash value +so make sure to include the -n flag. + +
+Custom UserId +The UserId generation is an open mechanism. You can set +spring.cloud.vault.app-id.user-id to any string and the configured +value will be used as static UserId. +A more advanced approach lets you set spring.cloud.vault.app-id.user-id to a +classname. This class must be on your classpath and must implement +the org.springframework.cloud.vault.AppIdUserIdMechanism interface +and the createUserId method. Spring Cloud Vault will obtain the UserId +by calling createUserId each time it authenticates using AppId to +obtain a token. + +bootstrap.yml +spring.cloud.vault: + authentication: APPID + app-id: + user-id: com.examlple.MyUserIdMechanism + + +MyUserIdMechanism.java +public class MyUserIdMechanism implements AppIdUserIdMechanism { + + @Override + public String createUserId() { + String userId = ... + return userId; + } +} + +See also: Vault Documentation: Using the App ID auth backend +
+
+
+AppRole authentication +AppRole is intended for machine +authentication, like the deprecated (since Vault 0.6.1) . +AppRole authentication consists of two hard to guess (secret) tokens: RoleId and SecretId. +Spring Vault supports AppRole authentication by providing either RoleId only +or together with a provided SecretId (push or pull mode). +RoleId and optionally SecretId must be provided by configuration, +Spring Vault will not look up these or create a custom SecretId. + +bootstrap.yml with AppRole authentication properties +spring.cloud.vault: + authentication: APPROLE + app-role: + role-id: bde2076b-cccb-3cf0-d57e-bca7b1e83a52 + + + +role-id sets the RoleId. + + + +bootstrap.yml with all AppRole authentication properties +spring.cloud.vault: + authentication: APPROLE + app-role: + role-id: bde2076b-cccb-3cf0-d57e-bca7b1e83a52 + secret-id: 1696536f-1976-73b1-b241-0b4213908d39 + app-auth-path: approle + + + +role-id sets the RoleId. + + +secret-id sets the SecretId. SecretId can be omitted if AppRole is configured without requiring SecretId (See bind_secret_id) + + +approle-path sets the path of the approle authentication mount to use + + +See also: Vault Documentation: Using the AppRole auth backend +
+
+AWS-EC2 authentication +The aws-ec2 +auth backend provides a secure introduction mechanism +for AWS EC2 instances, allowing automated retrieval of a Vault +token. Unlike most Vault authentication backends, this backend +does not require first-deploying, or provisioning security-sensitive +credentials (tokens, username/password, client certificates, etc.). +Instead, it treats AWS as a Trusted Third Party and uses the +cryptographically signed dynamic metadata information that uniquely +represents each EC2 instance. + +bootstrap.yml using AWS-EC2 Authentication +spring.cloud.vault: + authentication: AWS_EC2 + +AWS-EC2 authentication enables nonce by default to follow +the Trust On First Use (TOFU) principle. Any unintended party that +gains access to the PKCS#7 identity metadata can authenticate +against Vault. +During the first login, Spring Cloud Vault generates a nonce +that is stored in the auth backend aside the instance Id. +Re-authentication requires the same nonce to be sent. Any other +party does not have the nonce and can raise an alert in Vault for +further investigation. +The nonce is kept in memory and is lost during application restart. +You can configure a static nonce with spring.cloud.vault.aws-ec2.nonce. +AWS-EC2 authentication roles are optional and default to the AMI. +You can configure the authentication role by setting the +spring.cloud.vault.aws-ec2.role property. + +bootstrap.yml with configured role +spring.cloud.vault: + authentication: AWS_EC2 + aws-ec2: + role: application-server + + +bootstrap.yml with all AWS EC2 authentication properties +spring.cloud.vault: + authentication: AWS_EC2 + aws-ec2: + role: application-server + aws-ec2-path: aws-ec2 + identity-document: http://... + nonce: my-static-nonce + + + +authentication setting this value to AWS_EC2 selects the AWS EC2 +authentication method + + +role sets the name of the role against which the login is being attempted. + + +aws-ec2-path sets the path of the AWS EC2 mount to use + + +identity-document sets URL of the PKCS#7 AWS EC2 identity document + + +nonce used for AWS-EC2 authentication. An empty nonce defaults to nonce generation + + +See also: Vault Documentation: Using the aws auth backend +
+
+AWS-IAM authentication +The aws backend provides a secure +authentication mechanism for AWS IAM roles, allowing the automatic authentication with +vault based on the current IAM role of the running application. + Unlike most Vault authentication backends, this backend +does not require first-deploying, or provisioning security-sensitive +credentials (tokens, username/password, client certificates, etc.). +Instead, it treats AWS as a Trusted Third Party and uses the +4 pieces of information signed by the caller with their IAM credentials + to verify that the caller is indeed using that IAM role. +The current IAM role the application is running in is automatically calculated. +If you are running your application on AWS ECS then the application +will use the IAM role assigned to the ECS task of the running container. +If you are running your application naked on top of an EC2 instance then +the IAM role used will be the one assigned to the EC2 instance. +When using the AWS-IAM authentication you must create a role in Vault +and assign it to your IAM role. An empty role defaults to +the friendly name the current IAM role. + +bootstrap.yml with required AWS-IAM Authentication properties +spring.cloud.vault: + authentication: AWS_IAM + + +bootstrap.yml with all AWS-IAM Authentication properties +spring.cloud.vault: + authentication: AWS_IAM + aws-iam: + role: my-dev-role + aws-path: aws + server-id: some.server.name + + + +role sets the name of the role against which the login is being attempted. This should be bound to your IAM role. If one is not supplied then the friendly name of the current IAM user will be used as the vault role. + + +aws-path sets the path of the AWS mount to use + + +server-id sets the value to use for the X-Vault-AWS-IAM-Server-ID header preventing certain types of replay attacks. + + +AWS-IAM requires the AWS Java SDK dependency (com.amazonaws:aws-java-sdk-core) +as the authentication implementation uses AWS SDK types for credentials and request signing. +See also: Vault Documentation: Using the aws auth backend +
+
+TLS certificate authentication +The cert auth backend allows authentication using SSL/TLS client +certificates that are either signed by a CA or self-signed. +To enable cert authentication you need to: + + +Use SSL, see + + +Configure a Java Keystore that contains the client +certificate and the private key + + +Set the spring.cloud.vault.authentication to CERT + + + +bootstrap.yml +spring.cloud.vault: + authentication: CERT + ssl: + key-store: classpath:keystore.jks + key-store-password: changeit + cert-auth-path: cert + +See also: Vault Documentation: Using the Cert auth backend +
+
+Cubbyhole authentication +Cubbyhole authentication uses Vault primitives to provide a secured authentication +workflow. Cubbyhole authentication uses tokens as primary login method. +An ephemeral token is used to obtain a second, login VaultToken from Vault’s +Cubbyhole secret backend. The login token is usually longer-lived and used to +interact with Vault. The login token will be retrieved from a wrapped +response stored at /cubbyhole/response. +Creating a wrapped token + +Response Wrapping for token creation requires Vault 0.6.0 or higher. + + +Creating and storing tokens +$ vault token-create -wrap-ttl="10m" +Key Value +--- ----- +wrapping_token: 397ccb93-ff6c-b17b-9389-380b01ca2645 +wrapping_token_ttl: 0h10m0s +wrapping_token_creation_time: 2016-09-18 20:29:48.652957077 +0200 CEST +wrapped_accessor: 46b6aebb-187f-932a-26d7-4f3d86a68319 + + +bootstrap.yml +spring.cloud.vault: + authentication: CUBBYHOLE + token: 397ccb93-ff6c-b17b-9389-380b01ca2645 + +See also: + + +Vault Documentation: Tokens + + +Vault Documentation: Cubbyhole Secret Backend + + +Vault Documentation: Response Wrapping + + +
+
+Kubernetes authentication +Kubernetes authentication mechanism (since Vault 0.8.3) allows to authenticate with Vault using a Kubernetes Service Account Token. +The authentication is role based and the role is bound to a service account name and a namespace. +A file containing a JWT token for a pod’s service account is automatically mounted at /var/run/secrets/kubernetes.io/serviceaccount/token. + +bootstrap.yml with all Kubernetes authentication properties +spring.cloud.vault: + authentication: KUBERNETES + kubernetes: + role: my-dev-role + service-account-token-file: /var/run/secrets/kubernetes.io/serviceaccount/token + + + +role sets the Role. + + +service-account-token-file sets the location of the file containing the Kubernetes Service Account Token. Defaults to /var/run/secrets/kubernetes.io/serviceaccount/token. + + +See also: + + +Vault Documentation: Kubernetes + + +Kubernetes Documentation: Configure Service Accounts for Pods + + +
+ + +Secret Backends +
+Generic Backend +Spring Cloud Vault supports at the basic level the generic secret +backend. The generic secret backend allows storage of arbitrary +values as key-value store. A single context can store one or many +key-value tuples. Contexts can be organized hierarchically. +Spring Cloud Vault allows using the Application name +and a default context name (application) in combination with active +profiles. +/secret/{application}/{profile} +/secret/{application} +/secret/{default-context}/{profile} +/secret/{default-context} +The application name is determined by the properties: + + +spring.cloud.vault.generic.application-name + + +spring.cloud.vault.application-name + + +spring.application.name + + +Secrets can be obtained from other folders within the generic backend by adding their +paths to the application name, separated by commas. For example, given the application +name usefulapp,mysql1,projectx/aws, each of these folders will be used: + + +/secret/usefulapp + + +/secret/mysql1 + + +/secret/projectx/aws + + +Spring Cloud Vault adds all active profiles to the list of possible context paths. +No active profiles will skip accessing contexts with a profile name. +Properties are exposed like they are stored (i.e. without additional prefixes). + +spring.cloud.vault: + generic: + enabled: true + backend: secret + profile-separator: '/' + default-context: application + application-name: my-app + + + +enabled setting this value to false disables the secret backend +config usage + + +backend sets the path of the secret mount to use + + +default-context sets the context name used by all applications + + +application-name overrides the application name for use in the generic backend + + +profile-separator separates the profile name from the context in +property sources with profiles + + +See also: Vault Documentation: Using the generic secret backend +
+
+Consul +Spring Cloud Vault can obtain credentials for HashiCorp Consul. +The Consul integration requires the spring-cloud-vault-config-consul +dependency. + +pom.xml +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-vault-config-consul</artifactId> + <version>1.3.8.RELEASE</version> + </dependency> +</dependencies> + +The integration can be enabled by setting +spring.cloud.vault.consul.enabled=true (default false) and +providing the role name with spring.cloud.vault.consul.role=…. +The obtained token is stored in spring.cloud.consul.token +so using Spring Cloud Consul can pick up the generated +credentials without further configuration. You can configure +the property name by setting spring.cloud.vault.consul.token-property. + +spring.cloud.vault: + consul: + enabled: true + role: readonly + backend: consul + token-property: spring.cloud.consul.token + + + +enabled setting this value to true enables the Consul backend config usage + + +role sets the role name of the Consul role definition + + +backend sets the path of the Consul mount to use + + +token-property sets the property name in which the Consul ACL token is stored + + +See also: Vault Documentation: Setting up Consul with Vault +
+
+RabbitMQ +Spring Cloud Vault can obtain credentials for RabbitMQ. +The RabbitMQ integration requires the spring-cloud-vault-config-rabbitmq +dependency. + +pom.xml +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-vault-config-rabbitmq</artifactId> + <version>1.3.8.RELEASE</version> + </dependency> +</dependencies> + +The integration can be enabled by setting +spring.cloud.vault.rabbitmq.enabled=true (default false) +and providing the role name with spring.cloud.vault.rabbitmq.role=…. +Username and password are stored in spring.rabbitmq.username +and spring.rabbitmq.password so using Spring Boot will pick up the generated +credentials without further configuration. You can configure the property names +by setting spring.cloud.vault.rabbitmq.username-property and +spring.cloud.vault.rabbitmq.password-property. + +spring.cloud.vault: + rabbitmq: + enabled: true + role: readonly + backend: rabbitmq + username-property: spring.rabbitmq.username + password-property: spring.rabbitmq.password + + + +enabled setting this value to true enables the RabbitMQ backend config usage + + +role sets the role name of the RabbitMQ role definition + + +backend sets the path of the RabbitMQ mount to use + + +username-property sets the property name in which the RabbitMQ username is stored + + +password-property sets the property name in which the RabbitMQ password is stored + + +See also: Vault Documentation: Setting up RabbitMQ with Vault +
+
+AWS +Spring Cloud Vault can obtain credentials for AWS. +The AWS integration requires the spring-cloud-vault-config-aws +dependency. + +pom.xml +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-vault-config-aws</artifactId> + <version>1.3.8.RELEASE</version> + </dependency> +</dependencies> + +The integration can be enabled by setting +spring.cloud.vault.aws=true (default false) +and providing the role name with spring.cloud.vault.aws.role=…. +The access key and secret key are stored in cloud.aws.credentials.accessKey +and cloud.aws.credentials.secretKey so using Spring Cloud AWS will pick up the generated +credentials without further configuration. You can configure the property names +by setting spring.cloud.vault.aws.access-key-property and +spring.cloud.vault.aws.secret-key-property. + +spring.cloud.vault: + aws: + enabled: true + role: readonly + backend: aws + access-key-property: cloud.aws.credentials.accessKey + secret-key-property: cloud.aws.credentials.secretKey + + + +enabled setting this value to true enables the AWS backend config usage + + +role sets the role name of the AWS role definition + + +backend sets the path of the AWS mount to use + + +access-key-property sets the property name in which the AWS access key is stored + + +secret-key-property sets the property name in which the AWS secret key is stored + + +See also: Vault Documentation: Setting up AWS with Vault +
+ + +Database backends +Vault supports several database secret backends to generate database +credentials dynamically based on configured roles. This means +services that need to access a database no longer need to configure +credentials: they can request them from Vault, and use Vault’s leasing +mechanism to more easily roll keys. +Spring Cloud Vault integrates with these backends: + + + + + + + + + + + + + + +Using a database secret backend requires to enable the +backend in the configuration and the spring-cloud-vault-config-databases +dependency. +Vault ships since 0.7.1 with a dedicated database secret backend that allows +database integration via plugins. You can use that specific backend by adapting +one of the JDBC database properties above. Make sure to specify the appropriate +backend path, e.g. spring.cloud.vault.mysql.role.backend=database. + +pom.xml +<dependencies> + <dependency> + <groupId>org.springframework.cloud</groupId> + <artifactId>spring-cloud-vault-config-databases</artifactId> + <version>1.3.8.RELEASE</version> + </dependency> +</dependencies> + + +Enabling multiple JDBC-compliant databases will generate credentials +and store them by default in the same property keys hence property names for +JDBC secrets need to be configured separately. + +
+Apache Cassandra +Spring Cloud Vault can obtain credentials for Apache Cassandra. +The integration can be enabled by setting +spring.cloud.vault.cassandra.enabled=true (default false) and +providing the role name with spring.cloud.vault.cassandra.role=…. +Username and password are stored in spring.data.cassandra.username +and spring.data.cassandra.password so using Spring Boot will pick +up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.cassandra.username-property and +spring.cloud.vault.cassandra.password-property. + +spring.cloud.vault: + cassandra: + enabled: true + role: readonly + backend: cassandra + username-property: spring.data.cassandra.username + password-property: spring.data.cassandra.username + + + +enabled setting this value to true enables the Cassandra backend config usage + + +role sets the role name of the Cassandra role definition + + +backend sets the path of the Cassandra mount to use + + +username-property sets the property name in which the Cassandra username is stored + + +password-property sets the property name in which the Cassandra password is stored + + +See also: Vault Documentation: Setting up Apache Cassandra with Vault +
+
+MongoDB +Spring Cloud Vault can obtain credentials for MongoDB. +The integration can be enabled by setting +spring.cloud.vault.mongodb.enabled=true (default false) and +providing the role name with spring.cloud.vault.mongodb.role=…. +Username and password are stored in spring.data.mongodb.username +and spring.data.mongodb.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.mongodb.username-property and +spring.cloud.vault.mongodb.password-property. + +spring.cloud.vault: + mongodb: + enabled: true + role: readonly + backend: mongodb + username-property: spring.data.mongodb.username + password-property: spring.data.mongodb.password + + + +enabled setting this value to true enables the MongodB backend config usage + + +role sets the role name of the MongoDB role definition + + +backend sets the path of the MongoDB mount to use + + +username-property sets the property name in which the MongoDB username is stored + + +password-property sets the property name in which the MongoDB password is stored + + +See also: Vault Documentation: Setting up MongoDB with Vault +
+
+MySQL +Spring Cloud Vault can obtain credentials for MySQL. +The integration can be enabled by setting +spring.cloud.vault.mysql.enabled=true (default false) and +providing the role name with spring.cloud.vault.mysql.role=…. +Username and password are stored in spring.datasource.username +and spring.datasource.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.mysql.username-property and +spring.cloud.vault.mysql.password-property. + +spring.cloud.vault: + mysql: + enabled: true + role: readonly + backend: mysql + username-property: spring.datasource.username + password-property: spring.datasource.username + + + +enabled setting this value to true enables the MySQL backend config usage + + +role sets the role name of the MySQL role definition + + +backend sets the path of the MySQL mount to use + + +username-property sets the property name in which the MySQL username is stored + + +password-property sets the property name in which the MySQL password is stored + + +See also: Vault Documentation: Setting up MySQL with Vault +
+
+PostgreSQL +Spring Cloud Vault can obtain credentials for PostgreSQL. +The integration can be enabled by setting +spring.cloud.vault.postgresql.enabled=true (default false) and +providing the role name with spring.cloud.vault.postgresql.role=…. +Username and password are stored in spring.datasource.username +and spring.datasource.password so using Spring Boot will +pick up the generated credentials without further configuration. +You can configure the property names by setting +spring.cloud.vault.postgresql.username-property and +spring.cloud.vault.postgresql.password-property. + +spring.cloud.vault: + postgresql: + enabled: true + role: readonly + backend: postgresql + username-property: spring.datasource.username + password-property: spring.datasource.username + + + +enabled setting this value to true enables the PostgreSQL backend config usage + + +role sets the role name of the PostgreSQL role definition + + +backend sets the path of the PostgreSQL mount to use + + +username-property sets the property name in which the PostgreSQL username is stored + + +password-property sets the property name in which the PostgreSQL password is stored + + +See also: Vault Documentation: Setting up PostgreSQL with Vault +
+ + +Configure <literal>PropertySourceLocator</literal> behavior +Spring Cloud Vault uses property-based configuration to create PropertySources +for generic and discovered secret backends. +Discovered backends provide VaultSecretBackendDescriptor beans to describe the configuration +state to use secret backend as PropertySource. A SecretBackendMetadataFactory is required +to create a SecretBackendMetadata object which contains path, name and property transformation +configuration. +SecretBackendMetadata is used to back a particular PropertySource. +You can register an arbitrary number of beans implementing VaultConfigurer for customization. +Default generic and discovered backend registration is disabled if Spring Cloud Vault discovers +at least one VaultConfigurer bean. You can however enable default registration with +SecretBackendConfigurer.registerDefaultGenericSecretBackends() and SecretBackendConfigurer.registerDefaultDiscoveredSecretBackends(). + +public class CustomizationBean implements VaultConfigurer { + + @Override + public void addSecretBackends(SecretBackendConfigurer configurer) { + + configurer.add("secret/my-application"); + + configurer.registerDefaultGenericSecretBackends(false); + configurer.registerDefaultDiscoveredSecretBackends(true); + } +} + + +All customization is required to happen in the bootstrap context. Add your configuration +classes to META-INF/spring.factories at org.springframework.cloud.bootstrap.BootstrapConfiguration +in your application. + + + +Service Registry Configuration +You can use a DiscoveryClient (such as from Spring Cloud Consul) to locate +a Vault server by setting spring.cloud.vault.discovery.enabled=true (default false). +The net result of that is that your apps need a bootstrap.yml (or an environment variable) +with the appropriate discovery configuration. +The benefit is that the Vault can change its co-ordinates, as long as the discovery service +is a fixed point. The default service id is vault but you can change that on the client with +spring.cloud.vault.discovery.serviceId. +The discovery client implementations all support some kind of metadata map +(e.g. for Eureka we have eureka.instance.metadataMap). Some additional properties of the service +may need to be configured in its service registration metadata so that clients can connect +correctly. Service registries that do not provide details about transport layer security +need to provide a scheme metadata entry to be set either to https or http. +If no scheme is configured and the service is not exposed as secure service, then +configuration defaults to spring.cloud.vault.scheme which is https when it’s not set. + +spring.cloud.vault.discovery: + enabled: true + service-id: my-vault-service + + + +Vault Client Fail Fast +In some cases, it may be desirable to fail startup of a service if +it cannot connect to the Vault Server. If this is the desired +behavior, set the bootstrap configuration property +spring.cloud.vault.fail-fast=true and the client will halt with +an Exception. + +spring.cloud.vault: + fail-fast: true + + + +Vault Client SSL configuration +SSL can be configured declaratively by setting various properties. +You can set either javax.net.ssl.trustStore to configure +JVM-wide SSL settings or spring.cloud.vault.ssl.trust-store +to set SSL settings only for Spring Cloud Vault Config. + +spring.cloud.vault: + ssl: + trust-store: classpath:keystore.jks + trust-store-password: changeit + + + +trust-store sets the resource for the trust-store. SSL-secured Vault +communication will validate the Vault SSL certificate with the specified +trust-store. + + +trust-store-password sets the trust-store password + + +Please note that configuring spring.cloud.vault.ssl.* can be only +applied when either Apache Http Components or the OkHttp client +is on your class-path. + + +Lease lifecycle management (renewal and revocation) +With every secret, Vault creates a lease: +metadata containing information such as a time duration, +renewability, and more. +Vault promises that the data will be valid for the given duration, +or Time To Live (TTL). Once the lease is expired, Vault can +revoke the data, and the consumer of the secret can no longer +be certain that it is valid. +Spring Cloud Vault maintains a lease lifecycle beyond +the creation of login tokens and secrets. That said, +login tokens and secrets associated with a lease +are scheduled for renewal just before the lease expires +until terminal expiry. +Application shutdown revokes obtained login tokens and renewable +leases. +Secret service and database backends (such as MongoDB or MySQL) +usually generate a renewable lease so generated credentials will +be disabled on application shutdown. + +Static tokens are not renewed or revoked. + +Lease renewal and revocation is enabled by default and can +be disabled by setting spring.cloud.vault.config.lifecycle.enabled +to false. This is not recommended as leases can expire and +Spring Cloud Vault cannot longer access Vault or services +using generated credentials and valid credentials remain active +after application shutdown. + +spring.cloud.vault: + config.lifecycle.enabled: true + +See also: Vault Documentation: Lease, Renew, and Revoke + + + +Spring Cloud Function + +Mark Fisher, Dave Syer + + + +Introduction +Spring Cloud Function is a project with the following high-level goals: + + +Promote the implementation of business logic via functions. + + +Decouple the development lifecycle of business logic from any specific runtime target so that the same code can run as a web endpoint, a stream processor, or a task. + + +Support a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS). + + +Enable Spring Boot features (auto-configuration, dependency injection, metrics) on serverless providers. + + +It abstracts away all of the transport details and +infrastructure, allowing the developer to keep all the familiar tools +and processes, and focus firmly on business logic. +Here’s a complete, executable, testable Spring Boot application +(implementing a simple string manipulation): +@SpringBootApplication +public class Application { + + @Bean + public Function<Flux<String>, Flux<String>> uppercase() { + return flux -> flux.map(value -> value.toUpperCase()); + } + + public static void main(String[] args) { + SpringApplication.run(Application.class, args); + } +} +It’s just a Spring Boot application, so it can be built, run and +tested, locally and in a CI build, the same way as any other Spring +Boot application. The Function is from java.util and Flux is a +Reactive Streams Publisher from +Project Reactor. The function can be +accessed over HTTP or messaging. +Spring Cloud Function has 4 main features: + + +Wrappers for @Beans of type Function, Consumer and +Supplier, exposing them to the outside world as either HTTP +endpoints and/or message stream listeners/publishers with RabbitMQ, Kafka etc. + + +Compiling strings which are Java function bodies into bytecode, and +then turning them into @Beans that can be wrapped as above. + + +Deploying a JAR file containing such an application context with an +isolated classloader, so that you can pack them together in a single +JVM. + + +Adapters for AWS Lambda, Azure, Apache OpenWhisk and possibly other "serverless" service providers. + + + +Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. + + + +Getting Started +Build from the command line (and "install" the samples): +$ ./mvnw clean install +(If you like to YOLO add -DskipTests.) +Run one of the samples, e.g. +$ java -jar spring-cloud-function-samples/function-sample/target/*.jar +This runs the app and exposes its functions over HTTP, so you can +convert a string to uppercase, like this: +$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d Hello +HELLO +You can convert multiple strings (a Flux<String>) by separating them +with new lines +$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d 'Hello +> World' +HELLOWORLD +(You can use QJ in a terminal to insert a new line in a literal +string like that.) + + +Building and Running a Function +The sample @SpringBootApplication above has a function that can be +decorated at runtime by Spring Cloud Function to be an HTTP endpoint, +or a Stream processor, for instance with RabbitMQ, Apache Kafka or +JMS. +The @Beans can be Function, Consumer or Supplier (all from +java.util), and their parametric types can be String or POJO. A +Function is exposed as a Spring Cloud Stream Processor if +spring-cloud-function-stream is on the classpath. +A Consumer is also exposed as a Stream +Sink and a Supplier translates to a Stream Source. +HTTP endpoints are exposed if the Stream binder is spring-cloud-stream-binder-servlet. +Functions can be of Flux<String> or Flux<Pojo> and Spring Cloud +Function takes care of converting the data to and from the desired +types, as long as it comes in as plain text or (in the case of the +POJO) JSON. TBD: support for Flux<Message<Pojo>> and maybe plain +Pojo types (Fluxes implied and implemented by the framework). +Functions can be grouped together in a single application, or deployed +one-per-jar. It’s up to the developer to choose. An app with multiple +functions can be deployed multiple times in different "personalities", +exposing different functions over different physical transports. + + +Function Catalog and Flexible Function Signatures +One of the main features of Spring Cloud Function is to adapt and +support a range of type signatures for user-defined functions. So +users can supply a bean of type Function<String,String>, for +instance, and the FunctionCatalog will wrap it into a +Function<Flux<String>,Flux<String>>. Users don’t normally have to +care about the FunctionCatalog at all, but it is useful to know what +kind of functions are supported in user code. +Generally speaking users can expect that if they write a function for +a plain old Java type (or primitive wrapper), then the function +catalog will wrap it to a Flux of the same type. If the user writes +a function using Message (from spring-messaging) it will receive and +transmit headers from any adapter that supports key-value metadata +(e.g. HTTP headers). Here are the details. + + + + + + + +User Function +Catalog Registration + + + + + +Function<S,T> +Function<Flux<S>, Flux<T>> + + + +Function<Message<S>,Message<T>> +Function<Flux<Message<S>>, Flux<Message<T>>> + + + +Function<Flux<S>, Flux<T>> +Function<Flux<S>, Flux<T>> (pass through) + + + +Supplier<T> +Supplier<Flux<T>> + + + +Supplier<Flux<T>> +Supplier<Flux<T>> + + + +Consumer<T> +Function<Flux<T>, Mono<Void>> + + + +Consumer<Message<T>> +Function<Flux<Message<T>>, Mono<Void>> + + + +Consumer<Flux<T>> +Consumer<Flux<T>> + + + + + +Consumer is a little bit special because it has a void return type, +which implies blocking, at least potentially. Most likely you will not +need to write Consumer<Flux<?>>, but if you do need to do that, +remember to subscribe to the input flux. If you declare a Consumer +of a non publisher type (which is normal), it will be converted to a +function that returns a publisher, so that it can be subscribed to in +a controlled way. +A function catalog can contain a Supplier and a Function (or +Consumer) with the same name (like a GET and a POST to the same +resource). It can even contain a Consumer<Flux<>> with the same name +as a Function, but it cannot contain a Consumer<T> and a +Function<T,S> with the same name when T is not a Publisher +because the consumer would be converted to a Function and only one +of them can be registered. + + +Standalone Web Applications +The spring-cloud-function-web module has autoconfiguration that +activates when it is included in a Spring Boot web application (with +MVC support). There is also a spring-cloud-starter-function-web to +collect all the optional dependnecies in case you just want a simple +getting started experience. +With the web configurations activated your app will have an MVC +endpoint (on "/" by default, but configurable with +spring.cloud.function.web.path) that can be used to access the +functions in the application context. The supported content types are +plain text and JSON. + + + + + + + + + +Method +Path +Request +Response +Status + + + + +GET +/{supplier} +- +Items from the named supplier +200 OK + + +POST +/{consumer} +JSON object or text +Mirrors input and pushes request body into consumer +202 Accepted + + +POST +/{consumer} +JSON array or text with new lines +Mirrors input and pushes body into consumer one by one +202 Accepted + + +POST +/{function} +JSON object or text +The result of applying the named function +200 OK + + +POST +/{function} +JSON array or text with new lines +The result of applying the named function +200 OK + + +GET +/{function}/{item} +- +Convert the item into an object and return the result of applying the function +200 OK + + + + +As the table above shows the behaviour of the endpoint depends on the method and also the type of incoming request data. When the incoming data is single valued, and the target function is declared as obviously single valued (i.e. not returning a collection or Flux), then the response will also contain a single value. For multi-valued responses the client can ask for a server-sent event stream by sending `Accept: text/event-stream". If there is only one function (consumer etc.) then the name in the path is optional. Composite functions can be addressed using pipes or commas to separate function names (pipes are legal in URL paths, but a bit awkward to type on the command line). +Functions and consumers that are declared with input and output in Message<?> will see the request headers on the input messages, and the output message headers will be converted to HTTP headers. +When POSTing text the response format might be different with Spring Boot 2.0 and older versions, depending on the content negotiation (provide content type and accpt headers for the best results). + + +Standalone Streaming Applications +To send or receive messages from a broker (such as RabbitMQ or Kafka) you can use the spring-cloud-function-stream adapter. Add the adapter to your classpath along with the appropriate binder from Spring Cloud Stream. The adapter will bind to the message broker as a Processor (input and output streams) unless the user explicitly disables one or the other using spring.cloud.function.stream.{source,sink}.enabled=false. +An incoming message is routed to a function (or consumer). If there is only one, then the choice is obvious. If there are multiple functions that can accept an incoming message, the message is inspected to see if there is a stream_routekey header containing the name of a function. Routing headers or function names can be composed using a comma- or pipe-separated name. The header is also added to outgoing messages from a supplier. Messages with no route key can be routed exclusively to a function or consumer by specifying spring.cloud.function.stream.{processor,sink}.name. If a single function cannot be identified to process an incoming message there will be an error, unless you set spring.cloud.function.stream.shared=true, in which case such messages will be sent to all compatible functions. A single supplier can be chosen for output messages from a supplier (if more than one is available) using the spring.cloud.function.stream.source.name. + +some binders will fail on startup if the message broker is not available and the function catalog contains suppliers that immediately produce messages when accessed. You can switch off the automatic publishing from suppliers on startup using the spring.cloud.function.strean.supplier.enabled=false flag. + + + +Deploying a Packaged Function +Spring Cloud Function provides a "deployer" library that allows you to launch a jar file (or exploded archive, or set of jar files) with an isolated class loader and expose the functions defined in it. This is quite a powerful tool that would allow you to, for instance, adapt a function to a range of different input-output adapters without changing the target jar file. Serverless platforms often have this kind of feature built in, so you could see it as a building block for a function invoker in such a platform (indeed the Riff Java function invoker uses this library). +The standard entry point of the API is the Spring configuration annotation @EnableFunctionDeployer. If that is used in a Spring Boot application the deployer kicks in and looks for some configuration to tell it where to find the function jar. At a minimum the user has to provide a function.location which is a URL or resource location for the archive containing the functions. It can optionally use a maven: prefix to locate the artifact via a dependency lookup (see FunctionProperties for complete details). A Spring Boot application is bootstrapped from the jar file, using the MANIFEST.MF to locate a start class, so that a standard Spring Boot fat jar works well, for example. If the target jar can be launched successfully then the result is a function registered in the main application’s FunctionCatalog. The registered function can be applied by code in the main application, even though it was created in an isolated class loader (by deault). + + +Dynamic Compilation +There is a sample app that uses the function compiler to create a +function from a configuration property. The vanilla "function-sample" +also has that feature. And there are some scripts that you can run to +see the compilation happening at run time. To run these examples, +change into the scripts directory: +cd scripts +Also, start a RabbitMQ server locally (e.g. execute rabbitmq-server). +Start the Function Registry Service: +./function-registry.sh +Register a Function: +./registerFunction.sh -n uppercase -f "f->f.map(s->s.toString().toUpperCase())" +Run a REST Microservice using that Function: +./web.sh -f uppercase -p 9000 +curl -H "Content-Type: text/plain" -H "Accept: text/plain" localhost:9000/uppercase -d foo +Register a Supplier: +./registerSupplier.sh -n words -f "()->Flux.just(\"foo\",\"bar\")" +Run a REST Microservice using that Supplier: +./web.sh -s words -p 9001 +curl -H "Accept: application/json" localhost:9001/words +Register a Consumer: +./registerConsumer.sh -n print -t String -f "System.out::println" +Run a REST Microservice using that Consumer: +./web.sh -c print -p 9002 +curl -X POST -H "Content-Type: text/plain" -d foo localhost:9002/print +Run Stream Processing Microservices: +First register a streaming words supplier: +./registerSupplier.sh -n wordstream -f "()->Flux.interval(Duration.ofMillis(1000)).map(i->\"message-\"+i)" +Then start the source (supplier), processor (function), and sink (consumer) apps +(in reverse order): +./stream.sh -p 9103 -i uppercaseWords -c print +./stream.sh -p 9102 -i words -f uppercase -o uppercaseWords +./stream.sh -p 9101 -s wordstream -o words +The output will appear in the console of the sink app (one message per second, converted to uppercase): +MESSAGE-0 +MESSAGE-1 +MESSAGE-2 +MESSAGE-3 +MESSAGE-4 +MESSAGE-5 +MESSAGE-6 +MESSAGE-7 +MESSAGE-8 +MESSAGE-9 +... + + +Serverless Platform Adapters +As well as being able to run as a standalone process, a Spring Cloud +Function application can be adapted to run one of the existing +serverless platforms. In the project there are adapters for +AWS +Lambda, +Azure, +and +Apache +OpenWhisk. The Oracle Fn platform +has its own Spring Cloud Function adapter. And +Riff supports Java functions and its +Java Function +Invoker acts natively is an adapter for Spring Cloud Function jars. +
+AWS Lambda +The AWS adapter takes a Spring Cloud Function app and converts it to a form that can run in AWS Lambda. +
+Introduction +The adapter has a couple of generic request handlers that you can use. The most generic is SpringBootStreamHandler, which uses a Jackson ObjectMapper provided by Spring Boot to serialize and deserialize the objects in the function. There is also a SpringBootRequestHandler which you can extend, and provide the input and output types as type parameters (enabling AWS to inspect the class and do the JSON conversions itself). +If your app has more than one @Bean of type Function etc. then you can choose the one to use by configuring function.name (e.g. as FUNCTION_NAME environment variable in AWS). The functions are extracted from the Spring Cloud FunctionCatalog (searching first for Function then Consumer and finally Supplier). +
+
+Notes on JAR Layout +You don’t need the Spring Cloud Function Web or Stream adapter at runtime in Lambda, so you might need to exclude those before you create the JAR you send to AWS. A Lambda application has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample). The sample app creates 2 jar files, one with an aws classifier for deploying in Lambda, and one executable (thin) jar that includes spring-cloud-function-web at runtime. Spring Cloud Function will try and locate a "main class" for you from the JAR file manifest, using the Start-Class attribute (which will be added for you by the Spring Boot tooling if you use the starter parent). If there is no Start-Class in your manifest you can use an environment variable MAIN_CLASS when you deploy the function to AWS. +
+
+Upload +Build the sample under spring-cloud-function-samples/function-sample-aws and upload the -aws jar file to Lambda. The handler can be example.Handler or org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler (FQN of the class, not a method reference, although Lambda does accept method references). +./mvnw -U clean package +Using the AWS command line tools it looks like this: +aws lambda create-function --function-name Uppercase --role arn:aws:iam::[USERID]:role/service-role/[ROLE] --zip-file fileb://function-sample-aws/target/function-sample-aws-1.0.2.RELEASE-aws.jar --handler org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler --description "Spring Cloud Function Adapter Example" --runtime java8 --region us-east-1 --timeout 30 --memory-size 1024 --publish +The input type for the function in the AWS sample is a Foo with a single property called "value". So you would need this to test it: +{ + "value": "test" +} +
+
+Platfom Specific Features +
+HTTP and API Gateway +AWS has some platform-specific data types, including batching of messages, which is much more efficient than processing each one individually. To make use of these types you can write a function that depends on those types. Or you can rely on Spring to extract the data from the AWS types and convert it to a Spring Message. To do this you tell AWS that the function is of a specific generic handler type (depending on the AWS service) and provide a bean of type Function<Message<S>,Message<T>>, where S and T are your business data types. If there is more than one bean of type Function you may also need to configure the Spring Boot property function.name to be the name of the target bean (e.g. use FUNCTION_NAME as an environment variable). +The supported AWS services and generic handler types are listed below: + + + + + + + + +Service +AWS Types +Generic Handler + + + + + +API Gateway +APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent +org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler + + + +Kinesis +KinesisEvent +org.springframework.cloud.function.adapter.aws.SpringBootKinesisEventHandler + + + + + +For example, to deploy behind an API Gateway, use --handler org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler in your AWS command line (in via the UI) and define a @Bean of type Function<Message<Foo>,Message<Bar>> where Foo and Bar are POJO types (the data will be marshalled and unmarshalled by AWS using Jackson). +
+
+
+
+Azure Functions +The Azure adapter bootstraps a Spring Cloud Function context and channels function calls from the Azure framework into the user functions, using Spring Boot configuration where necessary. Azure Functions has quite a unique, but invasive programming model, involving annotations in user code that are specific to the platform. The Spring Cloud Function Azure adapter trades the convenience of these annotations for portability of the function implementations. Instead of using the annotations you have to write some JSON by hand (at least for now) to guide the platform to call the right methods in the adapter. +This project provides an adapter layer for a Spring Cloud Function application onto Azure. +You can write an app with a single @Bean of type Function and it will be deployable in Azure if you get the JAR file laid out right. +The adapter has a generic HTTP request handler that you can use optionally. +There is a AzureSpringBootRequestHandler which you must extend, and provide the input and output types as type parameters (enabling Azure to inspect the class and do the JSON conversions itself). +If your app has more than one @Bean of type Function etc. then you can choose the one to use by configuring function.name. +The functions are extracted from the Spring Cloud FunctionCatalog. +
+Notes on JAR Layout +You don’t need the Spring Cloud Function Web at runtime in Azure, so you need to exclude this before you create the JAR you deploy to Azure. +A function application on Azure has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample here). +The sample app creates the shaded jar file, with an azure classifier for deploying in Azure. +
+
+JSON Configuration +The Azure tooling needs to find some JSON configuration files to tell it how to deploy and integrate the function (e.g. which Java class to use as the entry point, and which triggers to use). Those files can be created with the Maven plugin for a non-Spring function, but the tooling doesn’t work yet with the adapter in its current form. There is an example function.json in the sample which hooks the function up as an HTTP endpoint: +{ + "scriptFile" : "../function-sample-azure-1.0.2.RELEASE-azure.jar", + "entryPoint" : "example.FooHandler.execute", + "bindings" : [ { + "type" : "httpTrigger", + "name" : "foo", + "direction" : "in", + "authLevel" : "anonymous", + "methods" : [ "get", "post" ] + }, { + "type" : "http", + "name" : "$return", + "direction" : "out" + } ], + "disabled" : false +} +
+
+Build +./mvnw -U clean package +
+
+Running the sample +You can run the sample locally, just like the other Spring Cloud Function samples: + + +and curl -H "Content-Type: text/plain" localhost:8080/function -d '{"value": "hello foobar"}'. +You will need the az CLI app and some node.js fu (see https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven for more detail). To deploy the function on Azure runtime: +$ az login +$ mvn azure-functions:deploy +On another terminal try this: curl https://<azure-function-url-from-the-log>/api/uppercase -d '{"value": "hello foobar!"}'. Please ensure that you use the right URL for the function above. Alternatively you can test the function in the Azure Dashboard UI (click on the function name, go to the right hand side and click "Test" and to the bottom right, "Run"). +The input type for the function in the Azure sample is a Foo with a single property called "value". So you need this to test it with something like below: +{ + "value": "foobar" +} +
+
+
+Apache Openwhisk +The OpenWhisk adapter is in the form of an executable jar that can be used in a a docker image to be deployed to Openwhisk. The platform works in request-response mode, listening on port 8080 on a specific endpoint, so the adapter is a simple Spring MVC application. +
+Quick Start +Implement a POF (be sure to use the functions package): +package functions; + +import java.util.function.Function; + +public class Uppercase implements Function<String, String> { + + public String apply(String input) { + return input.toUpperCase(); + } +} +Install it into your local Maven repository: +./mvnw clean install +Create a function.properties file that provides its Maven coordinates. For example: +dependencies.function: com.example:pof:0.0.1-SNAPSHOT +Copy the openwhisk runner JAR to the working directory (same directory as the properties file): +cp spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk/target/spring-cloud-function-adapter-openwhisk-1.0.2.RELEASE.jar runner.jar +Generate a m2 repo from the --thin.dryrun of the runner JAR with the above properties file: +java -jar -Dthin.root=m2 runner.jar --thin.name=function --thin.dryrun +Use the following Dockerfile: +FROM openjdk:8-jdk-alpine +VOLUME /tmp +COPY m2 /m2 +ADD runner.jar . +ADD function.properties . +ENV JAVA_OPTS="" +ENTRYPOINT [ "java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "runner.jar", "--thin.root=/m2", "--thin.name=function", "--function.name=uppercase"] +EXPOSE 8080 +
+ +you could use a Spring Cloud Function app, instead of just a jar with a POF in it, in which case you would have to change the way the app runs in the container so that it picks up the main class as a source file. For example, you could change the ENTRYPOINT above and add --spring.main.sources=com.example.SampleApplication. + +
+Build the Docker image: +docker build -t [username/appname] . +Push the Docker image: +docker push [username/appname] +Use the OpenWhisk CLI (e.g. after vagrant ssh) to create the action: +wsk action create example --docker [username/appname] +Invoke the action: +wsk action invoke example --result --param payload foo +{ + "result": "FOO" +} +
+
+ + + +Appendix: Compendium of Configuration Properties + + + + + + + + +Name +Default +Description + + + + +archaius.propagate.environmentChangedEvent +true +Propagates EnvironmentChanged events to Archaius ConfigurationManager. + + +encrypt.fail-on-error +true +Flag to say that a process should fail if there is an encryption or decryption error. + + +encrypt.key + +A symmetric key. As a stronger alternative consider using a keystore. + + +encrypt.key-store.alias + +Alias for a key in the store. + + +encrypt.key-store.location + +Location of the key store file, e.g. classpath:/keystore.jks. + + +encrypt.key-store.password + +Password that locks the keystore. + + +encrypt.key-store.secret + +Secret protecting the key (defaults to the same as the password). + + +encrypt.rsa.algorithm + +The RSA algorithm to use (DEFAULT or OEAP). Once it is set do not change it (or existing ciphers will not a decryptable). + + +encrypt.rsa.salt +deadbeef +Salt for the random secret used to encrypt cipher text. Once it is set do not change it (or existing ciphers will not a decryptable). + + +encrypt.rsa.strong +false +Flag to indicate that "strong" AES encryption should be used internally. If true then the GCM algorithm is applied to the AES encrypted bytes. Default is false (in which case "standard" CBC is used instead). Once it is set do not change it (or existing ciphers will not a decryptable). + + +endpoints.bus.enabled + + + + +endpoints.bus.id + + + + +endpoints.bus.sensitive + + + + +endpoints.consul.enabled + + + + +endpoints.consul.id + + + + +endpoints.consul.sensitive + + + + +endpoints.env.post.enabled +true +Enable changing the Environment through a POST to /env. + + +endpoints.features.enabled + + + + +endpoints.features.id + + + + +endpoints.features.sensitive + + + + +endpoints.pause.enabled +true +Enable the /pause endpoint (to send Lifecycle.stop()). + + +endpoints.pause.id + + + + +endpoints.pause.sensitive + + + + +endpoints.refresh.enabled +true +Enable the /refresh endpoint to refresh configuration and re-initialize refresh scoped beans. + + +endpoints.refresh.id + + + + +endpoints.refresh.sensitive + + + + +endpoints.restart.enabled +true +Enable the /restart endpoint to restart the application context. + + +endpoints.restart.id + + + + +endpoints.restart.pause-endpoint.enabled + + + + +endpoints.restart.pause-endpoint.id + + + + +endpoints.restart.pause-endpoint.sensitive + + + + +endpoints.restart.resume-endpoint.enabled + + + + +endpoints.restart.resume-endpoint.id + + + + +endpoints.restart.resume-endpoint.sensitive + + + + +endpoints.restart.sensitive + + + + +endpoints.restart.timeout +0 + + + +endpoints.resume.enabled +true +Enable the /resume endpoint (to send Lifecycle.start()). + + +endpoints.resume.id + + + + +endpoints.resume.sensitive + + + + +endpoints.routes.enabled + + + + +endpoints.routes.id + + + + +endpoints.routes.sensitive + + + + +endpoints.zookeeper.enabled +true +Enable the /zookeeper endpoint to inspect the state of zookeeper. + + +eureka.client.allow-redirects +false +Indicates whether server can redirect a client request to a backup server/cluster. If set to false, the server will handle the request directly, If set to true, it may send HTTP redirect to the client, with a new server location. + + +eureka.client.availability-zones + +Gets the list of availability zones (used in AWS data centers) for the region in which this instance resides. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds. + + +eureka.client.backup-registry-impl + +Gets the name of the implementation which implements BackupRegistry to fetch the registry information as a fall back option for only the first time when the eureka client starts. This may be needed for applications which needs additional resiliency for registry information without which it cannot operate. + + +eureka.client.cache-refresh-executor-exponential-back-off-bound +10 +Cache refresh executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred. + + +eureka.client.cache-refresh-executor-thread-pool-size +2 +The thread pool size for the cacheRefreshExecutor to initialise with + + +eureka.client.client-data-accept + +EurekaAccept name for client data accept + + +eureka.client.decoder-name + +This is a transient config and once the latest codecs are stable, can be removed (as there will only be one) + + +eureka.client.disable-delta +false +Indicates whether the eureka client should disable fetching of delta and should rather resort to getting the full registry information. Note that the delta fetches can reduce the traffic tremendously, because the rate of change with the eureka server is normally much lower than the rate of fetches. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds + + +eureka.client.dollar-replacement +_- +Get a replacement string for Dollar sign <code>$</code> during serializing/deserializing information in eureka server. + + +eureka.client.enabled +true +Flag to indicate that the Eureka client is enabled. + + +eureka.client.encoder-name + +This is a transient config and once the latest codecs are stable, can be removed (as there will only be one) + + +eureka.client.escape-char-replacement +__ +Get a replacement string for underscore sign <code>_</code> during serializing/deserializing information in eureka server. + + +eureka.client.eureka-connection-idle-timeout-seconds +30 +Indicates how much time (in seconds) that the HTTP connections to eureka server can stay idle before it can be closed. In the AWS environment, it is recommended that the values is 30 seconds or less, since the firewall cleans up the connection information after a few mins leaving the connection hanging in limbo + + +eureka.client.eureka-server-connect-timeout-seconds +5 +Indicates how long to wait (in seconds) before a connection to eureka server needs to timeout. Note that the connections in the client are pooled by org.apache.http.client.HttpClient and this setting affects the actual connection creation and also the wait time to get the connection from the pool. + + +eureka.client.eureka-server-d-n-s-name + +Gets the DNS name to be queried to get the list of eureka servers.This information is not required if the contract returns the service urls by implementing serviceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime. + + +eureka.client.eureka-server-port + +Gets the port to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS.This information is not required if the contract returns the service urls eurekaServerServiceUrls(String). The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime. + + +eureka.client.eureka-server-read-timeout-seconds +8 +Indicates how long to wait (in seconds) before a read from eureka server needs to timeout. + + +eureka.client.eureka-server-total-connections +200 +Gets the total number of connections that is allowed from eureka client to all eureka servers. + + +eureka.client.eureka-server-total-connections-per-host +50 +Gets the total number of connections that is allowed from eureka client to a eureka server host. + + +eureka.client.eureka-server-u-r-l-context + +Gets the URL context to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS. This information is not required if the contract returns the service urls from eurekaServerServiceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime. + + +eureka.client.eureka-service-url-poll-interval-seconds +0 +Indicates how often(in seconds) to poll for changes to eureka server information. Eureka servers could be added or removed and this setting controls how soon the eureka clients should know about it. + + +eureka.client.fetch-registry +true +Indicates whether this client should fetch eureka registry information from eureka server. + + +eureka.client.fetch-remote-regions-registry + +Comma separated list of regions for which the eureka registry information will be fetched. It is mandatory to define the availability zones for each of these regions as returned by availabilityZones. Failing to do so, will result in failure of discovery client startup. + + +eureka.client.filter-only-up-instances +true +Indicates whether to get the applications after filtering the applications for instances with only InstanceStatus UP states. + + +eureka.client.g-zip-content +true +Indicates whether the content fetched from eureka server has to be compressed whenever it is supported by the server. The registry information from the eureka server is compressed for optimum network traffic. + + +eureka.client.healthcheck.enabled +true +Enables the Eureka health check handler. + + +eureka.client.heartbeat-executor-exponential-back-off-bound +10 +Heartbeat executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred. + + +eureka.client.heartbeat-executor-thread-pool-size +2 +The thread pool size for the heartbeatExecutor to initialise with + + +eureka.client.initial-instance-info-replication-interval-seconds +40 +Indicates how long initially (in seconds) to replicate instance info to the eureka server + + +eureka.client.instance-info-replication-interval-seconds +30 +Indicates how often(in seconds) to replicate instance changes to be replicated to the eureka server. + + +eureka.client.log-delta-diff +false +Indicates whether to log differences between the eureka server and the eureka client in terms of registry information. Eureka client tries to retrieve only delta changes from eureka server to minimize network traffic. After receiving the deltas, eureka client reconciles the information from the server to verify it has not missed out some information. Reconciliation failures could happen when the client has had network issues communicating to server.If the reconciliation fails, eureka client gets the full registry information. While getting the full registry information, the eureka client can log the differences between the client and the server and this setting controls that. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSecondsr + + +eureka.client.on-demand-update-status-change +true +If set to true, local status updates via ApplicationInfoManager will trigger on-demand (but rate limited) register/updates to remote eureka servers + + +eureka.client.prefer-same-zone-eureka +true +Indicates whether or not this instance should try to use the eureka server in the same zone for latency and/or other reason. Ideally eureka clients are configured to talk to servers in the same zone The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds + + +eureka.client.property-resolver + + + + +eureka.client.proxy-host + +Gets the proxy host to eureka server if any. + + +eureka.client.proxy-password + +Gets the proxy password if any. + + +eureka.client.proxy-port + +Gets the proxy port to eureka server if any. + + +eureka.client.proxy-user-name + +Gets the proxy user name if any. + + +eureka.client.region +us-east-1 +Gets the region (used in AWS datacenters) where this instance resides. + + +eureka.client.register-with-eureka +true +Indicates whether or not this instance should register its information with eureka server for discovery by others. In some cases, you do not want your instances to be discovered whereas you just want do discover other instances. + + +eureka.client.registry-fetch-interval-seconds +30 +Indicates how often(in seconds) to fetch the registry information from the eureka server. + + +eureka.client.registry-refresh-single-vip-address + +Indicates whether the client is only interested in the registry information for a single VIP. + + +eureka.client.service-url + +Map of availability zone to list of fully qualified URLs to communicate with eureka server. Each value can be a single URL or a comma separated list of alternative locations. Typically the eureka server URLs carry protocol,host,port,context and version information if any. Example: https://ec2-256-156-243-129.compute-1.amazonaws.com:7001/eureka/ The changes are effective at runtime at the next service url refresh cycle as specified by eurekaServiceUrlPollIntervalSeconds. + + +eureka.client.use-dns-for-fetching-service-urls +false +Indicates whether the eureka client should use the DNS mechanism to fetch a list of eureka servers to talk to. When the DNS name is updated to have additional servers, that information is used immediately after the eureka client polls for that information as specified in eurekaServiceUrlPollIntervalSeconds. Alternatively, the service urls can be returned serviceUrls, but the users should implement their own mechanism to return the updated list in case of changes. The changes are effective at runtime. + + +eureka.dashboard.enabled +true +Flag to enable the Eureka dashboard. Default true. + + +eureka.dashboard.path +/ +The path to the Eureka dashboard (relative to the servlet path). Defaults to "/". + + +eureka.instance.a-s-g-name + +Gets the AWS autoscaling group name associated with this instance. This information is specifically used in an AWS environment to automatically put an instance out of service after the instance is launched and it has been disabled for traffic.. + + +eureka.instance.app-group-name + +Get the name of the application group to be registered with eureka. + + +eureka.instance.appname +unknown +Get the name of the application to be registered with eureka. + + +eureka.instance.data-center-info + +Returns the data center this instance is deployed. This information is used to get some AWS specific instance information if the instance is deployed in AWS. + + +eureka.instance.default-address-resolution-order +[] + + + +eureka.instance.environment + + + + +eureka.instance.health-check-url + +Gets the absolute health check page URL for this instance. The users can provide the healthCheckUrlPath if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime. + + +eureka.instance.health-check-url-path +/health +Gets the relative health check URL path for this instance. The health check page URL is then constructed out of the hostname and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. + + +eureka.instance.home-page-url + +Gets the absolute home page URL for this instance. The users can provide the homePageUrlPath if the home page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to use it as a landing page. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime. + + +eureka.instance.home-page-url-path +/ +Gets the relative home page URL Path for this instance. The home page URL is then constructed out of the hostName and the type of communication - secure or unsecure. It is normally used for informational purposes for other services to use it as a landing page. + + +eureka.instance.hostname + +The hostname if it can be determined at configuration time (otherwise it will be guessed from OS primitives). + + +eureka.instance.initial-status + +Initial status to register with rmeote Eureka server. + + +eureka.instance.instance-enabled-onit +false +Indicates whether the instance should be enabled for taking traffic as soon as it is registered with eureka. Sometimes the application might need to do some pre-processing before it is ready to take traffic. + + +eureka.instance.instance-id + +Get the unique Id (within the scope of the appName) of this instance to be registered with eureka. + + +eureka.instance.ip-address + +Get the IPAdress of the instance. This information is for academic purposes only as the communication from other instances primarily happen using the information supplied in {@link #getHostName(boolean)}. + + +eureka.instance.lease-expiration-duration-in-seconds +90 +Indicates the time in seconds that the eureka server waits since it received the last heartbeat before it can remove this instance from its view and there by disallowing traffic to this instance. Setting this value too long could mean that the traffic could be routed to the instance even though the instance is not alive. Setting this value too small could mean, the instance may be taken out of traffic because of temporary network glitches.This value to be set to atleast higher than the value specified in leaseRenewalIntervalInSeconds. + + +eureka.instance.lease-renewal-interval-in-seconds +30 +Indicates how often (in seconds) the eureka client needs to send heartbeats to eureka server to indicate that it is still alive. If the heartbeats are not received for the period specified in leaseExpirationDurationInSeconds, eureka server will remove the instance from its view, there by disallowing traffic to this instance. Note that the instance could still not take traffic if it implements HealthCheckCallback and then decides to make itself unavailable. + + +eureka.instance.metadata-map + +Gets the metadata name/value pairs associated with this instance. This information is sent to eureka server and can be used by other instances. + + +eureka.instance.namespace +eureka +Get the namespace used to find properties. Ignored in Spring Cloud. + + +eureka.instance.non-secure-port +80 +Get the non-secure port on which the instance should receive traffic. + + +eureka.instance.non-secure-port-enabled +true +Indicates whether the non-secure port should be enabled for traffic or not. + + +eureka.instance.prefer-ip-address +false +Flag to say that, when guessing a hostname, the IP address of the server should be used in prference to the hostname reported by the OS. + + +eureka.instance.registry.default-open-for-traffic-count +1 +Value used in determining when leases are cancelled, default to 1 for standalone. Should be set to 0 for peer replicated eurekas + + +eureka.instance.registry.expected-number-of-renews-per-min +1 + + + +eureka.instance.secure-health-check-url + +Gets the absolute secure health check page URL for this instance. The users can provide the secureHealthCheckUrl if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime. + + +eureka.instance.secure-port +443 +Get the Secure port on which the instance should receive traffic. + + +eureka.instance.secure-port-enabled +false +Indicates whether the secure port should be enabled for traffic or not. + + +eureka.instance.secure-virtual-host-name +unknown +Gets the secure virtual host name defined for this instance. This is typically the way other instance would find this instance by using the secure virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance. + + +eureka.instance.status-page-url + +Gets the absolute status page URL path for this instance. The users can provide the statusPageUrlPath if the status page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance. + + +eureka.instance.status-page-url-path +/info +Gets the relative status page URL path for this instance. The status page URL is then constructed out of the hostName and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance. + + +eureka.instance.virtual-host-name +unknown +Gets the virtual host name defined for this instance. This is typically the way other instance would find this instance by using the virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance. + + +eureka.server.a-s-g-cache-expiry-timeout-ms +0 + + + +eureka.server.a-s-g-query-timeout-ms +300 + + + +eureka.server.a-s-g-update-interval-ms +0 + + + +eureka.server.a-w-s-access-id + + + + +eureka.server.a-w-s-secret-key + + + + +eureka.server.batch-replication +false + + + +eureka.server.binding-strategy + + + + +eureka.server.delta-retention-timer-interval-in-ms +0 + + + +eureka.server.disable-delta +false + + + +eureka.server.disable-delta-for-remote-regions +false + + + +eureka.server.disable-transparent-fallback-to-other-region +false + + + +eureka.server.e-i-p-bind-rebind-retries +3 + + + +eureka.server.e-i-p-binding-retry-interval-ms +0 + + + +eureka.server.e-i-p-binding-retry-interval-ms-when-unbound +0 + + + +eureka.server.enable-replicated-request-compression +false + + + +eureka.server.enable-self-preservation +true + + + +eureka.server.eviction-interval-timer-in-ms +0 + + + +eureka.server.g-zip-content-from-remote-region +true + + + +eureka.server.json-codec-name + + + + +eureka.server.list-auto-scaling-groups-role-name +ListAutoScalingGroups + + + +eureka.server.log-identity-headers +true + + + +eureka.server.max-elements-in-peer-replication-pool +10000 + + + +eureka.server.max-elements-in-status-replication-pool +10000 + + + +eureka.server.max-idle-thread-age-in-minutes-for-peer-replication +15 + + + +eureka.server.max-idle-thread-in-minutes-age-for-status-replication +10 + + + +eureka.server.max-threads-for-peer-replication +20 + + + +eureka.server.max-threads-for-status-replication +1 + + + +eureka.server.max-time-for-replication +30000 + + + +eureka.server.min-available-instances-for-peer-replication +-1 + + + +eureka.server.min-threads-for-peer-replication +5 + + + +eureka.server.min-threads-for-status-replication +1 + + + +eureka.server.number-of-replication-retries +5 + + + +eureka.server.peer-eureka-nodes-update-interval-ms +0 + + + +eureka.server.peer-eureka-status-refresh-time-interval-ms +0 + + + +eureka.server.peer-node-connect-timeout-ms +200 + + + +eureka.server.peer-node-connection-idle-timeout-seconds +30 + + + +eureka.server.peer-node-read-timeout-ms +200 + + + +eureka.server.peer-node-total-connections +1000 + + + +eureka.server.peer-node-total-connections-per-host +500 + + + +eureka.server.prime-aws-replica-connections +true + + + +eureka.server.property-resolver + + + + +eureka.server.rate-limiter-burst-size +10 + + + +eureka.server.rate-limiter-enabled +false + + + +eureka.server.rate-limiter-full-fetch-average-rate +100 + + + +eureka.server.rate-limiter-privileged-clients + + + + +eureka.server.rate-limiter-registry-fetch-average-rate +500 + + + +eureka.server.rate-limiter-throttle-standard-clients +false + + + +eureka.server.registry-sync-retries +0 + + + +eureka.server.registry-sync-retry-wait-ms +0 + + + +eureka.server.remote-region-app-whitelist + + + + +eureka.server.remote-region-connect-timeout-ms +1000 + + + +eureka.server.remote-region-connection-idle-timeout-seconds +30 + + + +eureka.server.remote-region-fetch-thread-pool-size +20 + + + +eureka.server.remote-region-read-timeout-ms +1000 + + + +eureka.server.remote-region-registry-fetch-interval +30 + + + +eureka.server.remote-region-total-connections +1000 + + + +eureka.server.remote-region-total-connections-per-host +500 + + + +eureka.server.remote-region-trust-store + + + + +eureka.server.remote-region-trust-store-password +changeit + + + +eureka.server.remote-region-urls + + + + +eureka.server.remote-region-urls-with-name + + + + +eureka.server.renewal-percent-threshold +0.85 + + + +eureka.server.renewal-threshold-update-interval-ms +0 + + + +eureka.server.response-cache-auto-expiration-in-seconds +180 + + + +eureka.server.response-cache-update-interval-ms +0 + + + +eureka.server.retention-time-in-m-s-in-delta-queue +0 + + + +eureka.server.route53-bind-rebind-retries +3 + + + +eureka.server.route53-binding-retry-interval-ms +0 + + + +eureka.server.route53-domain-t-t-l +30 + + + +eureka.server.sync-when-timestamp-differs +true + + + +eureka.server.use-read-only-response-cache +true + + + +eureka.server.wait-time-in-ms-when-sync-empty +0 + + + +eureka.server.xml-codec-name + + + + +feign.client.config + + + + +feign.client.default-config +default + + + +feign.client.default-to-properties +true + + + +feign.compression.request.mime-types +[text/xml, application/xml, application/json] +The list of supported mime types. + + +feign.compression.request.min-request-size +2048 +The minimum threshold content size. + + +feign.httpclient.connection-timeout +2000 + + + +feign.httpclient.connection-timer-repeat +3000 + + + +feign.httpclient.disable-ssl-validation +false + + + +feign.httpclient.follow-redirects +true + + + +feign.httpclient.max-connections +200 + + + +feign.httpclient.max-connections-per-route +50 + + + +feign.httpclient.time-to-live +900 + + + +feign.httpclient.time-to-live-unit + + + + +health.config.enabled +false +Flag to indicate that the config server health indicator should be installed. + + +health.config.time-to-live +0 +Time to live for cached result, in milliseconds. Default 300000 (5 min). + + +hystrix.metrics.enabled +true +Enable Hystrix metrics polling. Defaults to true. + + +hystrix.metrics.polling-interval-ms +2000 +Interval between subsequent polling of metrics. Defaults to 2000 ms. + + +hystrix.shareSecurityContext +false +Enables auto-configuration of the Hystrix concurrency strategy plugin hook who will transfer the SecurityContext from your main thread to the one used by the Hystrix command. + + +management.health.refresh.enabled +true +Enable the health endpoint for the refresh scope. + + +management.health.zookeeper.enabled +true +Enable the health endpoint for zookeeper. + + +management.metrics.binders.hystrix.enabled +true +Enables creation of OK Http Client factory beans. + + +netflix.atlas.batch-size +10000 + + + +netflix.atlas.enabled +true + + + +netflix.atlas.uri + + + + +netflix.metrics.servo.cache-warning-threshold +1000 +When the ServoMonitorCache reaches this size, a warning is logged. This will be useful if you are using string concatenation in RestTemplate urls. + + +netflix.metrics.servo.registry-class +com.netflix.servo.BasicMonitorRegistry +Fully qualified class name for monitor registry used by Servo. + + +proxy.auth.load-balanced +false + + + +proxy.auth.routes + +Authentication strategy per route. + + +ribbon.eager-load.clients + + + + +ribbon.eager-load.enabled +false + + + +ribbon.eureka.enabled +true +Enables the use of Eureka with Ribbon. + + +ribbon.http.client.enabled +false +Deprecated property to enable Ribbon RestClient. + + +ribbon.okhttp.enabled +false +Enables the use of the OK HTTP Client with Ribbon. + + +ribbon.restclient.enabled +false +Enables the use of the deprecated Ribbon RestClient. + + +ribbon.secure-ports + + + + +spring.cloud.bus.ack.destination-service + +Service that wants to listen to acks. By default null (meaning all services). + + +spring.cloud.bus.ack.enabled +true +Flag to switch off acks (default on). + + +spring.cloud.bus.destination +springCloudBus +Name of Spring Cloud Stream destination for messages. + + +spring.cloud.bus.enabled +true +Flag to indicate that the bus is enabled. + + +spring.cloud.bus.env.enabled +true +Flag to switch off environment change events (default on). + + +spring.cloud.bus.refresh.enabled +true +Flag to switch off refresh events (default on). + + +spring.cloud.bus.trace.enabled +false +Flag to switch on tracing of acks (default off). + + +spring.cloud.cloudfoundry.discovery.enabled +true +Flag to indicate that discovery is enabled. + + +spring.cloud.cloudfoundry.discovery.heartbeat-frequency +5000 +Frequency in milliseconds of poll for heart beat. The client will poll on this frequency and broadcast a list of service ids. + + +spring.cloud.cloudfoundry.discovery.org + +Organization name to authenticate with (default to user’s default). + + +spring.cloud.cloudfoundry.discovery.password + +Password for user to authenticate and obtain token. + + +spring.cloud.cloudfoundry.discovery.space + +Space name to authenticate with (default to user’s default). + + +spring.cloud.cloudfoundry.discovery.url +https://api.run.pivotal.io +URL of Cloud Foundry API (Cloud Controller). + + +spring.cloud.cloudfoundry.discovery.username + +Username to authenticate (usually an email address). + + +spring.cloud.compatibility-verifier.compatible-boot-versions +1.5.x +Default accepted versions for the Spring Boot dependency. You can set {@code x} for the patch version if you don’t want to specify a concrete value. Example: {@code 3.4.x} + + +spring.cloud.compatibility-verifier.enabled +false +Enables creation of Spring Cloud compatibility verification. + + +spring.cloud.config.allow-override +true +Flag to indicate that {@link #isOverrideSystemProperties() systemPropertiesOverride} can be used. Set to false to prevent users from changing the default accidentally. Default true. + + +spring.cloud.config.authorization + +Authorization token used by the client to connect to the server. + + +spring.cloud.config.discovery.enabled +false +Flag to indicate that config server discovery is enabled (config server URL will be looked up via discovery). + + +spring.cloud.config.discovery.service-id +configserver +Service id to locate config server. + + +spring.cloud.config.enabled +true +Flag to say that remote configuration is enabled. Default true; + + +spring.cloud.config.fail-fast +false +Flag to indicate that failure to connect to the server is fatal (default false). + + +spring.cloud.config.headers + +Additional headers used to create the client request. + + +spring.cloud.config.label + +The label name to use to pull remote configuration properties. The default is set on the server (generally "master" for a git based server). + + +spring.cloud.config.name + +Name of application used to fetch remote properties. + + +spring.cloud.config.override-none +false +Flag to indicate that when {@link #setAllowOverride(boolean) allowOverride} is true, external properties should take lowest priority, and not override any existing property sources (including local config files). Default false. + + +spring.cloud.config.override-system-properties +true +Flag to indicate that the external properties should override system properties. Default true. + + +spring.cloud.config.password + +The password to use (HTTP Basic) when contacting the remote server. + + +spring.cloud.config.profile +default +The default profile to use when fetching remote configuration (comma-separated). Default is "default". + + +spring.cloud.config.retry.initial-interval +1000 +Initial retry interval in milliseconds. + + +spring.cloud.config.retry.max-attempts +6 +Maximum number of attempts. + + +spring.cloud.config.retry.max-interval +2000 +Maximum interval for backoff. + + +spring.cloud.config.retry.multiplier +1.1 +Multiplier for next interval. + + +spring.cloud.config.server.bootstrap +false +Flag indicating that the config server should initialize its own Environment with properties from the remote repository. Off by default because it delays startup but can be useful when embedding the server in another application. + + +spring.cloud.config.server.default-application-name +application +Default application name when incoming requests do not have a specific one. + + +spring.cloud.config.server.default-label + +Default repository label when incoming requests do not have a specific label. + + +spring.cloud.config.server.default-profile +default +Default application profile when incoming requests do not have a specific one. + + +spring.cloud.config.server.encrypt.enabled +true +Enable decryption of environment properties before sending to client. + + +spring.cloud.config.server.git.basedir + +Base directory for local working copy of repository. + + +spring.cloud.config.server.git.clone-on-start +false +Flag to indicate that the repository should be cloned on startup (not on demand). Generally leads to slower startup but faster first query. + + +spring.cloud.config.server.git.default-label +master + + + +spring.cloud.config.server.git.delete-untracked-branches +false +Flag to indicate that the branch should be deleted locally if it’s origin tracked branch was removed. + + +spring.cloud.config.server.git.environment + + + + +spring.cloud.config.server.git.force-pull +false +Flag to indicate that the repository should force pull. If true discard any local changes and take from remote repository. + + +spring.cloud.config.server.git.git-credentials-provider + +The credentials provider to use to connect to the Git repository. + + +spring.cloud.config.server.git.git-factory + + + + +spring.cloud.config.server.git.host-key + + + + +spring.cloud.config.server.git.host-key-algorithm + + + + +spring.cloud.config.server.git.ignore-local-ssh-settings +false + + + +spring.cloud.config.server.git.known-hosts-file + + + + +spring.cloud.config.server.git.last-refresh +0 +Time of the last refresh of the git repository + + +spring.cloud.config.server.git.order + + + + +spring.cloud.config.server.git.passphrase + +Passphrase for unlocking your ssh private key. + + +spring.cloud.config.server.git.password + +Password for authentication with remote repository. + + +spring.cloud.config.server.git.preferred-authentications + + + + +spring.cloud.config.server.git.private-key + + + + +spring.cloud.config.server.git.proxy-host + + + + +spring.cloud.config.server.git.proxy-port + + + + +spring.cloud.config.server.git.refresh-rate +0 +Time (in seconds) between refresh of the git repository + + +spring.cloud.config.server.git.repos + +Map of repository identifier to location and other properties. + + +spring.cloud.config.server.git.search-paths + +Search paths to use within local working copy. By default searches only the root. + + +spring.cloud.config.server.git.strict-host-key-checking +true +Reject incoming SSH host keys from remote servers not in the known host list. + + +spring.cloud.config.server.git.timeout +5 +Timeout (in seconds) for obtaining HTTP or SSH connection (if applicable). Default 5 seconds. + + +spring.cloud.config.server.git.transport-config-callback + +Transport configuration callback for JGit commands. + + +spring.cloud.config.server.git.uri + +URI of remote repository. + + +spring.cloud.config.server.git.username + +Username for authentication with remote repository. + + +spring.cloud.config.server.health.repositories + + + + +spring.cloud.config.server.jdbc.order +0 + + + +spring.cloud.config.server.jdbc.sql +SELECT KEY, VALUE from PROPERTIES where APPLICATION=? and PROFILE=? and LABEL=? + + + +spring.cloud.config.server.native.add-label-locations +true +Flag to determine whether label locations should be added. + + +spring.cloud.config.server.native.default-label +master + + + +spring.cloud.config.server.native.fail-on-error +false +Flag to determine how to handle exceptions during decryption (default false). + + +spring.cloud.config.server.native.order + + + + +spring.cloud.config.server.native.search-locations +[] +Locations to search for configuration files. Defaults to the same as a Spring Boot app so [classpath:/,classpath:/config/,file:./,file:./config/]. + + +spring.cloud.config.server.native.version + +Version string to be reported for native repository + + +spring.cloud.config.server.overrides + +Extra map for a property source to be sent to all clients unconditionally. + + +spring.cloud.config.server.prefix + +Prefix for configuration resource paths (default is empty). Useful when embedding in another application when you don’t want to change the context path or servlet path. + + +spring.cloud.config.server.strip-document-from-yaml +true +Flag to indicate that YAML documents that are text or collections (not a map) should be returned in "native" form. + + +spring.cloud.config.server.svn.basedir + +Base directory for local working copy of repository. + + +spring.cloud.config.server.svn.default-label +trunk +The default label for environment properties requests. + + +spring.cloud.config.server.svn.environment + + + + +spring.cloud.config.server.svn.order + + + + +spring.cloud.config.server.svn.passphrase + +Passphrase for unlocking your ssh private key. + + +spring.cloud.config.server.svn.password + +Password for authentication with remote repository. + + +spring.cloud.config.server.svn.search-paths + +Search paths to use within local working copy. By default searches only the root. + + +spring.cloud.config.server.svn.strict-host-key-checking +true +Reject incoming SSH host keys from remote servers not in the known host list. + + +spring.cloud.config.server.svn.uri + +URI of remote repository. + + +spring.cloud.config.server.svn.username + +Username for authentication with remote repository. + + +spring.cloud.config.server.vault.order + + + + +spring.cloud.config.token + +Security Token passed thru to underlying environment repository. + + +spring.cloud.config.uri +http://localhost:8888 +The URI of the remote server (default http://localhost:8888). + + +spring.cloud.config.username + +The username to use (HTTP Basic) when contacting the remote server. + + +spring.cloud.consul.config.acl-token + + + + +spring.cloud.consul.config.data-key +data +If format is Format.PROPERTIES or Format.YAML then the following field is used as key to look up consul for configuration. + + +spring.cloud.consul.config.default-context +application + + + +spring.cloud.consul.config.enabled +true + + + +spring.cloud.consul.config.fail-fast +true +Throw exceptions during config lookup if true, otherwise, log warnings. + + +spring.cloud.consul.config.format + + + + +spring.cloud.consul.config.name + +Alternative to spring.application.name to use in looking up values in consul KV. + + +spring.cloud.consul.config.prefix +config + + + +spring.cloud.consul.config.profile-separator +, + + + +spring.cloud.consul.config.watch.delay +1000 +The value of the fixed delay for the watch in millis. Defaults to 1000. + + +spring.cloud.consul.config.watch.enabled +true +If the watch is enabled. Defaults to true. + + +spring.cloud.consul.config.watch.wait-time +55 +The number of seconds to wait (or block) for watch query, defaults to 55. Needs to be less than default ConsulClient (defaults to 60). To increase ConsulClient timeout create a ConsulClient bean with a custom ConsulRawClient with a custom HttpClient. + + +spring.cloud.consul.discovery.acl-token + + + + +spring.cloud.consul.discovery.catalog-services-watch-delay +10 + + + +spring.cloud.consul.discovery.catalog-services-watch-timeout +2 + + + +spring.cloud.consul.discovery.datacenters + +Map of serviceId’s → datacenter to query for in server list. This allows looking up services in another datacenters. + + +spring.cloud.consul.discovery.default-query-tag + +Tag to query for in service list if one is not listed in serverListQueryTags. + + +spring.cloud.consul.discovery.default-zone-metadata-name +zone +Service instance zone comes from metadata. This allows changing the metadata tag name. + + +spring.cloud.consul.discovery.deregister +true +Disable automatic de-registration of service in consul. + + +spring.cloud.consul.discovery.enabled +true +Is service discovery enabled? + + +spring.cloud.consul.discovery.fail-fast +true +Throw exceptions during service registration if true, otherwise, log warnings (defaults to true). + + +spring.cloud.consul.discovery.health-check-critical-timeout + +Timeout to deregister services critical for longer than timeout (e.g. 30m). Requires consul version 7.x or higher. + + +spring.cloud.consul.discovery.health-check-interval +10s +How often to perform the health check (e.g. 10s), defaults to 10s. + + +spring.cloud.consul.discovery.health-check-path +/health +Alternate server path to invoke for health checking + + +spring.cloud.consul.discovery.health-check-timeout + +Timeout for health check (e.g. 10s). + + +spring.cloud.consul.discovery.health-check-tls-skip-verify + +Skips certificate verification during service checks if true, otherwise runs certificate verification. + + +spring.cloud.consul.discovery.health-check-url + +Custom health check url to override default + + +spring.cloud.consul.discovery.heartbeat.enabled +false + + + +spring.cloud.consul.discovery.heartbeat.heartbeat-interval + + + + +spring.cloud.consul.discovery.heartbeat.interval-ratio + + + + +spring.cloud.consul.discovery.heartbeat.ttl-unit +s + + + +spring.cloud.consul.discovery.heartbeat.ttl-value +30 + + + +spring.cloud.consul.discovery.hostname + +Hostname to use when accessing server + + +spring.cloud.consul.discovery.instance-group + +Service instance group + + +spring.cloud.consul.discovery.instance-id + +Unique service instance id + + +spring.cloud.consul.discovery.instance-zone + +Service instance zone + + +spring.cloud.consul.discovery.ip-address + +IP address to use when accessing service (must also set preferIpAddress to use) + + +spring.cloud.consul.discovery.lifecycle.enabled +true + + + +spring.cloud.consul.discovery.management-port + +Port to register the management service under (defaults to management port) + + +spring.cloud.consul.discovery.management-suffix +management +Suffix to use when registering management service + + +spring.cloud.consul.discovery.management-tags + +Tags to use when registering management service + + +spring.cloud.consul.discovery.port + +Port to register the service under (defaults to listening port) + + +spring.cloud.consul.discovery.prefer-agent-address +false +Source of how we will determine the address to use + + +spring.cloud.consul.discovery.prefer-ip-address +false +Use ip address rather than hostname during registration + + +spring.cloud.consul.discovery.query-passing +false +Add the 'passing` parameter to /v1/health/service/serviceName. This pushes health check passing to the server. + + +spring.cloud.consul.discovery.register +true +Register as a service in consul. + + +spring.cloud.consul.discovery.register-health-check +true +Register health check in consul. Useful during development of a service. + + +spring.cloud.consul.discovery.scheme +http +Whether to register an http or https service + + +spring.cloud.consul.discovery.server-list-query-tags + +Map of serviceId’s → tag to query for in server list. This allows filtering services by a single tag. + + +spring.cloud.consul.discovery.service-name + +Service name + + +spring.cloud.consul.discovery.tags + +Tags to use when registering service + + +spring.cloud.consul.enabled +true +Is spring cloud consul enabled + + +spring.cloud.consul.host +localhost +Consul agent hostname. Defaults to 'localhost'. + + +spring.cloud.consul.port +8500 +Consul agent port. Defaults to '8500'. + + +spring.cloud.consul.retry.initial-interval +1000 +Initial retry interval in milliseconds. + + +spring.cloud.consul.retry.max-attempts +6 +Maximum number of attempts. + + +spring.cloud.consul.retry.max-interval +2000 +Maximum interval for backoff. + + +spring.cloud.consul.retry.multiplier +1.1 +Multiplier for next interval. + + +spring.cloud.consul.tls.certificate-password + +Password to open the certificate. + + +spring.cloud.consul.tls.certificate-path + +File path to the certificate. + + +spring.cloud.consul.tls.key-store-instance-type + +Type of key framework to use. + + +spring.cloud.consul.tls.key-store-password + +Password to an external keystore + + +spring.cloud.consul.tls.key-store-path + +Path to an external keystore + + +spring.cloud.discovery.client.composite-indicator.enabled +true +Enables discovery client composite health indicator. + + +spring.cloud.discovery.client.health-indicator.enabled +true + + + +spring.cloud.discovery.client.health-indicator.include-description +true + + + +spring.cloud.discovery.client.simple.instances + + + + +spring.cloud.discovery.client.simple.local.metadata + +Metadata for the service instance. Can be used by discovery clients to modify their behaviour per instance, e.g. when load balancing. + + +spring.cloud.discovery.client.simple.local.service-id + +The identifier or name for the service. Multiple instances might share the same service id. + + +spring.cloud.discovery.client.simple.local.uri + +The URI of the service instance. Will be parsed to extract the scheme, hos and port. + + +spring.cloud.discovery.enabled +true +Enables discovery client health indicators. + + +spring.cloud.features.enabled +true +Enables the features endpoint. + + +spring.cloud.gateway.proxy.headers + +Fixed header values that will be added to all downstream requests. + + +spring.cloud.gateway.proxy.sensitive + +A set of sensitive header names that will not be sent downstream by default. + + +spring.cloud.httpclientfactories.apache.enabled +true +Enables creation of Apache Http Client factory beans. + + +spring.cloud.httpclientfactories.ok.enabled +true +Enables creation of OK Http Client factory beans. + + +spring.cloud.hypermedia.refresh.fixed-delay +5000 + + + +spring.cloud.hypermedia.refresh.initial-delay +10000 + + + +spring.cloud.inetutils.default-hostname +localhost +The default hostname. Used in case of errors. + + +spring.cloud.inetutils.default-ip-address +127.0.0.1 +The default ipaddress. Used in case of errors. + + +spring.cloud.inetutils.ignored-interfaces + +List of Java regex expressions for network interfaces that will be ignored. + + +spring.cloud.inetutils.preferred-networks + +List of Java regex expressions for network addresses that will be preferred. + + +spring.cloud.inetutils.timeout-seconds +1 +Timeout in seconds for calculating hostname. + + +spring.cloud.inetutils.use-only-site-local-interfaces +false +Use only interfaces with site local addresses. See {@link InetAddress#isSiteLocalAddress()} for more details. + + +spring.cloud.loadbalancer.retry.enabled +true + + + +spring.cloud.refresh.enabled +true +Enables autoconfiguration for the refresh scope and associated features. + + +spring.cloud.service-registry.auto-registration.enabled +true +If Auto-Service Registration is enabled, default to true. + + +spring.cloud.service-registry.auto-registration.fail-fast +false +Should startup fail if there is no AutoServiceRegistration, default to false. + + +spring.cloud.service-registry.auto-registration.register-management +true +Whether to register the management as a service, defaults to true + + +spring.cloud.stream.binders + + + + +spring.cloud.stream.bindings + + + + +spring.cloud.stream.consul.binder.event-timeout +5 + + + +spring.cloud.stream.default-binder + + + + +spring.cloud.stream.dynamic-destinations +[] + + + +spring.cloud.stream.instance-count +1 + + + +spring.cloud.stream.instance-index +0 + + + +spring.cloud.stream.integration.message-handler-not-propagated-headers + +Message header names that will NOT be copied from the inbound message. + + +spring.cloud.util.enabled +true +Enables creation of Spring Cloud utility beans. + + +spring.cloud.vault.app-id.app-id-path +app-id +Mount path of the AppId authentication backend. + + +spring.cloud.vault.app-id.network-interface + +Network interface hint for the "MAC_ADDRESS" UserId mechanism. + + +spring.cloud.vault.app-id.user-id +MAC_ADDRESS +UserId mechanism. Can be either "MAC_ADDRESS", "IP_ADDRESS", a string or a class name. + + +spring.cloud.vault.app-role.app-role-path +approle +Mount path of the AppId authentication backend. + + +spring.cloud.vault.app-role.role-id + +The RoleId. + + +spring.cloud.vault.app-role.secret-id + +The SecretId. + + +spring.cloud.vault.application-name +application +Application name for AppId authentication. + + +spring.cloud.vault.authentication + + + + +spring.cloud.vault.aws-ec2.aws-ec2-path +aws-ec2 +Mount path of the AWS-EC2 authentication backend. + + +spring.cloud.vault.aws-ec2.identity-document +http://169.254.169.254/latest/dynamic/instance-identity/pkcs7 +URL of the AWS-EC2 PKCS7 identity document. + + +spring.cloud.vault.aws-ec2.nonce + +Nonce used for AWS-EC2 authentication. An empty nonce defaults to nonce generation. + + +spring.cloud.vault.aws-ec2.role + +Name of the role, optional. + + +spring.cloud.vault.aws-ec2.use-nonce +true +Flag whether to generate and send a nonce. @deprecated not used, will be removed in a future version. + + +spring.cloud.vault.aws-iam.aws-path +aws +Mount path of the AWS authentication backend. + + +spring.cloud.vault.aws-iam.role + +Name of the role, optional. Defaults to the friendly IAM name if not set. + + +spring.cloud.vault.aws-iam.server-name + +Name of the server used to set {@code X-Vault-AWS-IAM-Server-ID} header in the headers of login requests. + + +spring.cloud.vault.aws.access-key-property +cloud.aws.credentials.accessKey +Target property for the obtained access key. + + +spring.cloud.vault.aws.backend +aws +aws backend path. + + +spring.cloud.vault.aws.enabled +false +Enable aws backend usage. + + +spring.cloud.vault.aws.role + +Role name for credentials. + + +spring.cloud.vault.aws.secret-key-property +cloud.aws.credentials.secretKey +Target property for the obtained secret key. + + +spring.cloud.vault.cassandra.backend +cassandra +Cassandra backend path. + + +spring.cloud.vault.cassandra.enabled +false +Enable cassandra backend usage. + + +spring.cloud.vault.cassandra.password-property +spring.data.cassandra.password +Target property for the obtained password. + + +spring.cloud.vault.cassandra.role + +Role name for credentials. + + +spring.cloud.vault.cassandra.username-property +spring.data.cassandra.username +Target property for the obtained username. + + +spring.cloud.vault.config.lifecycle + + + + +spring.cloud.vault.config.order +0 +Used to set a {@link org.springframework.core.env.PropertySource} priority. This is useful to use Vault as an override on other property sources. @see org.springframework.core.PriorityOrdered + + +spring.cloud.vault.connection-timeout +5000 +Connection timeout; + + +spring.cloud.vault.consul.backend +consul +Consul backend path. + + +spring.cloud.vault.consul.enabled +false +Enable consul backend usage. + + +spring.cloud.vault.consul.role + +Role name for credentials. + + +spring.cloud.vault.consul.token-property +spring.cloud.consul.token +Target property for the obtained token. + + +spring.cloud.vault.discovery.enabled +false +Flag to indicate that Vault server discovery is enabled (vault server URL will be looked up via discovery). + + +spring.cloud.vault.discovery.service-id +vault +Service id to locate Vault. + + +spring.cloud.vault.enabled +true +Enable Vault config server. + + +spring.cloud.vault.fail-fast +false +Fail fast if data cannot be obtained from Vault. + + +spring.cloud.vault.generic.application-name +application +Application name to be used for the context. + + +spring.cloud.vault.generic.backend +secret +Name of the default backend. + + +spring.cloud.vault.generic.default-context +application +Name of the default context. + + +spring.cloud.vault.generic.enabled +true +Enable the generic backend. + + +spring.cloud.vault.generic.profile-separator +/ +Profile-separator to combine application name and profile. + + +spring.cloud.vault.host +localhost +Vault server host. + + +spring.cloud.vault.kubernetes.kubernetes-path +kubernetes +Mount path of the Kubernetes authentication backend. + + +spring.cloud.vault.kubernetes.role + +Name of the role against which the login is being attempted. + + +spring.cloud.vault.kubernetes.service-account-token-file +/var/run/secrets/kubernetes.io/serviceaccount/token +Path to the service account token file. + + +spring.cloud.vault.mongodb.backend +mongodb +Cassandra backend path. + + +spring.cloud.vault.mongodb.enabled +false +Enable mongodb backend usage. + + +spring.cloud.vault.mongodb.password-property +spring.data.mongodb.password +Target property for the obtained password. + + +spring.cloud.vault.mongodb.role + +Role name for credentials. + + +spring.cloud.vault.mongodb.username-property +spring.data.mongodb.username +Target property for the obtained username. + + +spring.cloud.vault.mysql.backend +mysql +mysql backend path. + + +spring.cloud.vault.mysql.enabled +false +Enable mysql backend usage. + + +spring.cloud.vault.mysql.password-property +spring.datasource.password +Target property for the obtained username. + + +spring.cloud.vault.mysql.role + +Role name for credentials. + + +spring.cloud.vault.mysql.username-property +spring.datasource.username +Target property for the obtained username. + + +spring.cloud.vault.port +8200 +Vault server port. + + +spring.cloud.vault.postgresql.backend +postgresql +postgresql backend path. + + +spring.cloud.vault.postgresql.enabled +false +Enable postgresql backend usage. + + +spring.cloud.vault.postgresql.password-property +spring.datasource.password +Target property for the obtained username. + + +spring.cloud.vault.postgresql.role + +Role name for credentials. + + +spring.cloud.vault.postgresql.username-property +spring.datasource.username +Target property for the obtained username. + + +spring.cloud.vault.rabbitmq.backend +rabbitmq +rabbitmq backend path. + + +spring.cloud.vault.rabbitmq.enabled +false +Enable rabbitmq backend usage. + + +spring.cloud.vault.rabbitmq.password-property +spring.rabbitmq.password +Target property for the obtained password. + + +spring.cloud.vault.rabbitmq.role + +Role name for credentials. + + +spring.cloud.vault.rabbitmq.username-property +spring.rabbitmq.username +Target property for the obtained username. + + +spring.cloud.vault.read-timeout +15000 +Read timeout; + + +spring.cloud.vault.scheme +https +Protocol scheme. Can be either "http" or "https". + + +spring.cloud.vault.ssl.cert-auth-path +cert +Mount path of the TLS cert authentication backend. + + +spring.cloud.vault.ssl.key-store + +Trust store that holds certificates and private keys. + + +spring.cloud.vault.ssl.key-store-password + +Password used to access the key store. + + +spring.cloud.vault.ssl.trust-store + +Trust store that holds SSL certificates. + + +spring.cloud.vault.ssl.trust-store-password + +Password used to access the trust store. + + +spring.cloud.vault.token + +Static vault token. Required if {@link #authentication} is {@code TOKEN}. + + +spring.cloud.vault.uri + +Vault URI. Can be set with scheme, host and port. + + +spring.cloud.zookeeper.base-sleep-time-ms +50 +Initial amount of time to wait between retries + + +spring.cloud.zookeeper.block-until-connected-unit + +The unit of time related to blocking on connection to Zookeeper + + +spring.cloud.zookeeper.block-until-connected-wait +10 +Wait time to block on connection to Zookeeper + + +spring.cloud.zookeeper.connect-string +localhost:2181 +Connection string to the Zookeeper cluster + + +spring.cloud.zookeeper.default-health-endpoint + +Default health endpoint that will be checked to verify that a dependency is alive + + +spring.cloud.zookeeper.dependencies + +Mapping of alias to ZookeeperDependency. From Ribbon perspective the alias is actually serviceID since Ribbon can’t accept nested structures in serviceID + + +spring.cloud.zookeeper.dependency-configurations + + + + +spring.cloud.zookeeper.dependency-names + + + + +spring.cloud.zookeeper.discovery.enabled +true + + + +spring.cloud.zookeeper.discovery.initial-status + +The initial status of this instance (defaults to {@link StatusConstants#STATUS_UP}). + + +spring.cloud.zookeeper.discovery.instance-host + +Predefined host with which a service can register itself in Zookeeper. Corresponds to the {code address} from the URI spec. + + +spring.cloud.zookeeper.discovery.instance-id + +Id used to register with zookeeper. Defaults to a random UUID. + + +spring.cloud.zookeeper.discovery.instance-port + +Port to register the service under (defaults to listening port) + + +spring.cloud.zookeeper.discovery.instance-ssl-port + +Ssl port of the registered service. + + +spring.cloud.zookeeper.discovery.metadata + +Gets the metadata name/value pairs associated with this instance. This information is sent to zookeeper and can be used by other instances. + + +spring.cloud.zookeeper.discovery.register +true +Register as a service in zookeeper. + + +spring.cloud.zookeeper.discovery.root +/services +Root Zookeeper folder in which all instances are registered + + +spring.cloud.zookeeper.discovery.uri-spec +{scheme}://{address}:{port} +The URI specification to resolve during service registration in Zookeeper + + +spring.cloud.zookeeper.enabled +true +Is Zookeeper enabled + + +spring.cloud.zookeeper.max-retries +10 +Max number of times to retry + + +spring.cloud.zookeeper.max-sleep-ms +500 +Max time in ms to sleep on each retry + + +spring.cloud.zookeeper.prefix + +Common prefix that will be applied to all Zookeeper dependencies' paths + + +spring.integration.poller.fixed-delay +1000 +Fixed delay for default poller. + + +spring.integration.poller.max-messages-per-poll +1 +Maximum messages per poll for the default poller. + + +spring.sleuth.annotation.enabled +true + + + +spring.sleuth.async.configurer.enabled +true +Enable default AsyncConfigurer. + + +spring.sleuth.async.enabled +true +Enable instrumenting async related components so that the tracing information is passed between threads. + + +spring.sleuth.enabled +true + + + +spring.sleuth.feign.enabled +true +Enable span information propagation when using Feign. + + +spring.sleuth.feign.processor.enabled +true +Enable post processor that wraps Feign Context in its tracing representations. + + +spring.sleuth.hystrix.strategy.enabled +true +Enable custom HystrixConcurrencyStrategy that wraps all Callable instances into their Sleuth representative - the TraceCallable. + + +spring.sleuth.integration.enabled +true +Enable Spring Integration sleuth instrumentation. + + +spring.sleuth.integration.patterns +* +An array of simple patterns against which channel names will be matched. Default is * (all channels). See org.springframework.util.PatternMatchUtils.simpleMatch(String, String). + + +spring.sleuth.integration.websockets.enabled +true +Enable tracing for WebSockets. + + +spring.sleuth.keys.async.class-name-key +class +Simple name of the class with a method annotated with {@code @Async} from which the asynchronous process started @see org.springframework.scheduling.annotation.Async + + +spring.sleuth.keys.async.method-name-key +method +Name of the method annotated with {@code @Async} @see org.springframework.scheduling.annotation.Async + + +spring.sleuth.keys.async.prefix + +Prefix for header names if they are added as tags. + + +spring.sleuth.keys.async.thread-name-key +thread +Name of the thread that executed the async method @see org.springframework.scheduling.annotation.Async + + +spring.sleuth.keys.http.headers + +Additional headers that should be added as tags if they exist. If the header value is multi-valued, the tag value will be a comma-separated, single-quoted list. + + +spring.sleuth.keys.http.host +http.host +The domain portion of the URL or host header. Example: "mybucket.s3.amazonaws.com". Used to filter by host as opposed to ip address. + + +spring.sleuth.keys.http.method +http.method +The HTTP method, or verb, such as "GET" or "POST". Used to filter against an http route. + + +spring.sleuth.keys.http.path +http.path +The absolute http path, without any query parameters. Example: "/objects/abcd-ff". Used to filter against an http route, portably with zipkin v1. In zipkin v1, only equals filters are supported. Dropping query parameters makes the number of distinct URIs less. For example, one can query for the same resource, regardless of signing parameters encoded in the query line. This does not reduce cardinality to a HTTP single route. For example, it is common to express a route as an http URI template like "/resource/{resource_id}". In systems where only equals queries are available, searching for {@code http.uri=/resource} won’t match if the actual request was "/resource/abcd-ff". Historical note: This was commonly expressed as "http.uri" in zipkin, eventhough it was most often just a path. + + +spring.sleuth.keys.http.prefix +http. +Prefix for header names if they are added as tags. + + +spring.sleuth.keys.http.request-size +http.request.size +The size of the non-empty HTTP request body, in bytes. Ex. "16384" <p>Large uploads can exceed limits or contribute directly to latency. + + +spring.sleuth.keys.http.response-size +http.response.size +The size of the non-empty HTTP response body, in bytes. Ex. "16384" <p>Large downloads can exceed limits or contribute directly to latency. + + +spring.sleuth.keys.http.status-code +http.status_code +The HTTP response code, when not in 2xx range. Ex. "503" Used to filter for error status. 2xx range are not logged as success codes are less interesting for latency troubleshooting. Omitting saves at least 20 bytes per span. + + +spring.sleuth.keys.http.url +http.url +The entire URL, including the scheme, host and query parameters if available. Ex. "https://mybucket.s3.amazonaws.com/objects/abcd-ff?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Algorithm=AWS4-HMAC-SHA256…​" Combined with {@link #method}, you can understand the fully-qualified request line. This is optional as it may include private data or be of considerable length. + + +spring.sleuth.keys.hystrix.command-group +commandGroup +Name of the command group. Hystrix uses the command group key to group together commands such as for reporting, alerting, dashboards, or team/library ownership. @see com.netflix.hystrix.HystrixCommandGroupKey + + +spring.sleuth.keys.hystrix.command-key +commandKey +Name of the command key. Describes the name for the given command. A key to represent a {@link com.netflix.hystrix.HystrixCommand} for monitoring, circuit-breakers, metrics publishing, caching and other such uses. @see com.netflix.hystrix.HystrixCommandKey + + +spring.sleuth.keys.hystrix.prefix + +Prefix for header names if they are added as tags. + + +spring.sleuth.keys.hystrix.thread-pool-key +threadPoolKey +Name of the thread pool key. The thread-pool key represents a {@link com.netflix.hystrix.HystrixThreadPool} for monitoring, metrics publishing, caching, and other such uses. A {@link com.netflix.hystrix.HystrixCommand} is associated with a single {@link com.netflix.hystrix.HystrixThreadPool} as retrieved by the {@link com.netflix.hystrix.HystrixThreadPoolKey} injected into it, or it defaults to one created using the {@link com.netflix.hystrix.HystrixCommandGroupKey} it is created with. @see com.netflix.hystrix.HystrixThreadPoolKey + + +spring.sleuth.keys.message.headers + +Additional headers that should be added as tags if they exist. If the header value is not a String it will be converted to a String using its toString() method. + + +spring.sleuth.keys.message.payload.size +message/payload-size +An estimate of the size of the payload if available. + + +spring.sleuth.keys.message.payload.type +message/payload-type +The type of the payload. + + +spring.sleuth.keys.message.prefix +message/ +Prefix for header names if they are added as tags. + + +spring.sleuth.keys.mvc.controller-class +mvc.controller.class +The lower case, hyphen delimited name of the class that processes the request. Ex. class named "BookController" will result in "book-controller" tag value. + + +spring.sleuth.keys.mvc.controller-method +mvc.controller.method +The lower case, hyphen delimited name of the class that processes the request. Ex. method named "listOfBooks" will result in "list-of-books" tag value. + + +spring.sleuth.log.slf4j.enabled +true +Enable a {@link Slf4jSpanLogger} that prints tracing information in the logs. + + +spring.sleuth.log.slf4j.name-skip-pattern + +Name pattern for which span should not be printed in the logs. + + +spring.sleuth.metric.enabled +true +Enable calculation of accepted and dropped spans through {@link org.springframework.boot.actuate.metrics.CounterService} + + +spring.sleuth.metric.span.accepted-name +counter.span.accepted + + + +spring.sleuth.metric.span.dropped-name +counter.span.dropped + + + +spring.sleuth.rxjava.schedulers.hook.enabled +true +Enable support for RxJava via RxJavaSchedulersHook. + + +spring.sleuth.rxjava.schedulers.ignoredthreads +[HystrixMetricPoller, ^RxComputation.*$] +Thread names for which spans will not be sampled. + + +spring.sleuth.sampler.percentage +0.1 +Percentage of requests that should be sampled. E.g. 1.0 - 100% requests should be sampled. The precision is whole-numbers only (i.e. there’s no support for 0.1% of the traces). + + +spring.sleuth.scheduled.enabled +true +Enable tracing for {@link org.springframework.scheduling.annotation.Scheduled}. + + +spring.sleuth.scheduled.skip-pattern + +Pattern for the fully qualified name of a class that should be skipped. + + +spring.sleuth.supports-join +true +When true, your tracing system allows sharing a span ID between a client and server span + + +spring.sleuth.trace-id128 +false +When true, generate 128-bit trace IDs instead of 64-bit ones. + + +spring.sleuth.web.client.enabled +true +Enable interceptor injecting into {@link org.springframework.web.client.RestTemplate} + + +spring.sleuth.web.enabled +true +When true enables instrumentation for web applications + + +spring.sleuth.web.filter-order + +Order in which the {@link TraceFilter} should be registered. Defaults to {@link TraceFilter#ORDER} + + +spring.sleuth.web.skip-pattern +/api-docs.* +/autoconfig + + +/configprops +/dump +/health + + +/info +/metrics.* +/mappings + + +/trace +/swagger.* +.*\.png + + +.*\.css +.*\.js +.*\.html + + +/favicon.ico +/hystrix.stream +Pattern for URLs that should be skipped in tracing + + +spring.sleuth.zuul.enabled +true +Enable span information propagation when using Zuul. + + +stubrunner.classifier +stubs +The classifier to use by default in ivy co-ordinates for a stub. + + +stubrunner.consumer-name + +You can override the default {@code spring.application.name} of this field by setting a value to this parameter. + + +stubrunner.ids +[] +The ids of the stubs to run in "ivy" notation ([groupId]:artifactId:[version]:[classifier][:port]). {@code groupId}, {@code classifier}, {@code version} and {@code port} can be optional. + + +stubrunner.ids-to-service-ids + +Mapping of Ivy notation based ids to serviceIds inside your application Example "a:b" → "myService" "artifactId" → "myOtherService" + + +stubrunner.mappings-output-folder + +Dumps the mappings of each HTTP server to the selected folder + + +stubrunner.max-port +15000 +Max value of a port for the automatically started WireMock server + + +stubrunner.min-port +10000 +Min value of a port for the automatically started WireMock server + + +stubrunner.password + +Repository password + + +stubrunner.proxy-host + +Repository proxy host + + +stubrunner.proxy-port + +Repository proxy port + + +stubrunner.repository-root + +The repository root to use (where the stubs should be downloaded from) + + +stubrunner.stubs-per-consumer +false +Should only stubs for this particular consumer get registered in HTTP server stub. + + +stubrunner.username + +Repository username + + +stubrunner.work-offline +false +Should the stubs be checked for presence only locally + + +turbine.stream.enabled +true +Enables Autoconfiguration for a Spring Cloud Turbine using Spring Cloud Stream. + + +zuul.add-host-header +false +Flag to determine whether the proxy forwards the Host header. + + +zuul.add-proxy-headers +true +Flag to determine whether the proxy adds X-Forwarded-* headers. + + +zuul.force-original-query-string-encoding +false +Flag to force the original query string encoding when building the backend URI in SimpleHostRoutingFilter. When activated, query string will be built using HttpServletRequest getQueryString() method instead of UriTemplate. Note that this flag is not used in RibbonRoutingFilter with services found via DiscoveryClient (like Eureka). + + +zuul.host.connect-timeout-millis +2000 +The connection timeout in millis. Defaults to 2000. + + +zuul.host.max-per-route-connections +20 +The maximum number of connections that can be used by a single route. + + +zuul.host.max-total-connections +200 +The maximum number of total connections the proxy can hold open to backends. + + +zuul.host.socket-timeout-millis +10000 +The socket timeout in millis. Defaults to 10000. + + +zuul.host.time-to-live +-1 +The lifetime for the connection pool. + + +zuul.host.time-unit + +The time unit for timeToLive. + + +zuul.ignore-local-service +true + + + +zuul.ignore-security-headers +true +Flag to say that SECURITY_HEADERS are added to ignored headers if spring security is on the classpath. By setting ignoreSecurityHeaders to false we can switch off this default behaviour. This should be used together with disabling the default spring security headers see https://docs.spring.io/spring-security/site/docs/current/reference/html/headers.html#default-security-headers + + +zuul.ignored-headers + +Names of HTTP headers to ignore completely (i.e. leave them out of downstream requests and drop them from downstream responses). + + +zuul.ignored-patterns + + + + +zuul.ignored-services + +Set of service names not to consider for proxying automatically. By default all services in the discovery client will be proxied. + + +zuul.include-debug-header +false +Setting for SendResponseFilter to conditionally include X-Zuul-Debug-Header header. + + +zuul.initial-stream-buffer-size +8192 +Setting for SendResponseFilter for the initial stream buffer size. + + +zuul.prefix + +A common prefix for all routes. + + +zuul.remove-semicolon-content +true +Flag to say that path elements past the first semicolon can be dropped. + + +zuul.retryable +false +Flag for whether retry is supported by default (assuming the routes themselves support it). + + +zuul.ribbon-isolation-strategy + + + + +zuul.ribbon.eager-load.enabled +false +Enables eager loading of Ribbon clients on startup. + + +zuul.routes + +Map of route names to properties. + + +zuul.semaphore.max-semaphores +100 +The maximum number of total semaphores for Hystrix. + + +zuul.sensitive-headers + +List of sensitive headers that are not passed to downstream requests. Defaults to a "safe" set of headers that commonly contain user credentials. It’s OK to remove those from the list if the downstream service is part of the same system as the proxy, so they are sharing authentication data. If using a physical URL outside your own domain, then generally it would be a bad idea to leak user credentials. + + +zuul.servlet-path +/zuul +Path to install Zuul as a servlet (not part of Spring MVC). The servlet is more memory efficient for requests with large bodies, e.g. file uploads. + + +zuul.set-content-length +false +Setting for SendResponseFilter to conditionally set Content-Length header. + + +zuul.ssl-hostname-validation-enabled +true +Flag to say whether the hostname for ssl connections should be verified or not. Default is true. This should only be used in test setups! + + +zuul.strip-prefix +true +Flag saying whether to strip the prefix from the path before forwarding. + + +zuul.thread-pool.thread-pool-key-prefix + +A prefix for HystrixThreadPoolKey of hystrix’s thread pool that is allocated to each service Id. This property is only applicable when using THREAD as ribbonIsolationStrategy and useSeparateThreadPools = true + + +zuul.thread-pool.use-separate-thread-pools +false +Flag to determine whether RibbonCommands should use separate thread pools for hystrix. By setting to true, RibbonCommands will be executed in a hystrix’s thread pool that it is associated with. Each RibbonCommand will be associated with a thread pool according to its commandKey (serviceId). As default, all commands will be executed in a single thread pool whose threadPoolKey is "RibbonCommand". This property is only applicable when using THREAD as ribbonIsolationStrategy + + +zuul.trace-request-body +true +Flag to say that request bodies can be traced. + + + + + + + \ No newline at end of file