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Antora migration (#323)

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* Updates maven to 3.9.0

* Migrate Structure

* Insert explicit ids for headers

* Remove unnecessary asciidoc attributes

* Copy default antora files

* Fix indentation for all pages

* Split files

* Generate a default navigation

* Remove includes

* Fix cross references

* Enable Section Summary TOC for small pages

* More antora customization
This commit is contained in:
Spencer Gibb
2023-09-13 19:01:09 -04:00
committed by GitHub
parent 0df6974de0
commit a3a046dc62
29 changed files with 835 additions and 1009 deletions
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32
.github/workflows/deploy-docs.yml vendored Normal file
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@@ -0,0 +1,32 @@
name: Deploy Docs
on:
push:
branches-ignore: [ gh-pages ]
tags: '**'
repository_dispatch:
types: request-build-reference # legacy
#schedule:
#- cron: '0 10 * * *' # Once per day at 10am UTC
workflow_dispatch:
permissions:
actions: write
jobs:
build:
runs-on: ubuntu-latest
# if: github.repository_owner == 'spring-cloud'
steps:
- name: Checkout
uses: actions/checkout@v3
with:
ref: docs-build
fetch-depth: 1
- name: Dispatch (partial build)
if: github.ref_type == 'branch'
env:
GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
run: gh workflow run deploy-docs.yml -r $(git rev-parse --abbrev-ref HEAD) -f build-refname=${{ github.ref_name }}
- name: Dispatch (full build)
if: github.ref_type == 'tag'
env:
GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
run: gh workflow run deploy-docs.yml -r $(git rev-parse --abbrev-ref HEAD)

6
.gitignore vendored
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@@ -17,3 +17,9 @@ _site/
.DS_Store
.vscode/
.flattened-pom.xml
node
node_modules
build
package.json
package-lock.json

19
.mvn/wrapper/maven-wrapper.properties vendored
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@@ -1 +1,18 @@
distributionUrl=https://repo1.maven.org/maven2/org/apache/maven/apache-maven/3.5.0/apache-maven-3.5.0-bin.zip
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.0/apache-maven-3.9.0-bin.zip
wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.1/maven-wrapper-3.1.1.jar

375
README.adoc
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@@ -5,300 +5,32 @@ Edit the files in the src/main/asciidoc/ directory instead.
////
image::https://travis-ci.org/spring-cloud/spring-cloud-zookeeper.svg?branch=master[Build Status, link=https://travis-ci.org/spring-cloud/spring-cloud-zookeeper]
image::https://github.com/spring-cloud/spring-cloud-zookeeper/workflows/Build/badge.svg?style=svg["Actions Status", link="https://github.com/spring-cloud/spring-cloud-zookeeper/actions"]
:doctype: book
:idprefix:
:idseparator: -
:toc: left
:toclevels: 4
:tabsize: 4
:numbered:
:sectanchors:
:sectnums:
:icons: font
:hide-uri-scheme:
:docinfo: shared,private
:sc-ext: java
:project-full-name: Spring Cloud Zookeeper
This project provides Zookeeper integrations for Spring Boot applications through
autoconfiguration and binding to the Spring Environment and other Spring programming model
idioms. With a few annotations, you can quickly enable and configure the common patterns
inside your application and build large distributed systems with Zookeeper based
components. The provided patterns include Service Discovery and Configuration. The project
also provides client-side load-balancing via integration with Spring Cloud LoadBalancer.
[[quick-start]]
= Quick Start
:doctype: book
:idprefix:
:idseparator: -
:toc: left
:toclevels: 4
:tabsize: 4
:numbered:
:sectanchors:
:sectnums:
:icons: font
:hide-uri-scheme:
:docinfo: shared,private
:sc-ext: java
:project-full-name: Spring Cloud Zookeeper
== Quick Start
This quick start walks through using Spring Cloud Zookeeper for Service Discovery and Distributed Configuration.
First, run Zookeeper on your machine. Then you can access it and use it as a Service Registry and Configuration source with Spring Cloud Zookeeper.
=== Discovery Client Usage
To use these features in an application, you can build it as a Spring Boot application that depends on `spring-cloud-zookeeper-core` and `spring-cloud-zookeeper-discovery`.
The most convenient way to add the dependency is with a Spring Boot starter: `org.springframework.cloud:spring-cloud-starter-zookeeper-discovery`.
We recommend using dependency management and `spring-boot-starter-parent`.
The following example shows a typical Maven configuration:
[source,xml,indent=0]
.pom.xml
----
<project>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>{spring-boot-version}</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
----
The following example shows a typical Gradle setup:
[source,groovy,indent=0]
.build.gradle
----
plugins {
id 'org.springframework.boot' version ${spring-boot-version}
id 'io.spring.dependency-management' version ${spring-dependency-management-version}
id 'java'
}
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.cloud:spring-cloud-starter-zookeeper-discovery'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
}
dependencyManagement {
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
}
}
----
WARNING: Depending on the version you are using, you might need to adjust Apache Zookeeper version used in your project.
You can read more about it in the <<spring-cloud-zookeeper-install,Install Zookeeper section>>.
Now you can create a standard Spring Boot application, such as the following HTTP server:
----
@SpringBootApplication
@RestController
public class Application {
@GetMapping("/")
public String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
----
When this HTTP server runs, it connects to Zookeeper, which runs on the default local port (2181).
To modify the startup behavior, you can change the location of Zookeeper by using `application.properties`, as shown in the following example:
----
spring:
cloud:
zookeeper:
connect-string: localhost:2181
----
You can now use `DiscoveryClient`, `@LoadBalanced RestTemplate`, or `@LoadBalanced WebClient.Builder` to retrieve services and instances data from Zookeeper, as shown in the following example:
[source,java,indent=0]
----
@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;
}
----
=== Distributed Configuration Usage
To use these features in an application, you can build it as a Spring Boot application that depends on `spring-cloud-zookeeper-core` and `spring-cloud-zookeeper-config`.
The most convenient way to add the dependency is with a Spring Boot starter: `org.springframework.cloud:spring-cloud-starter-zookeeper-config`.
We recommend using dependency management and `spring-boot-starter-parent`.
The following example shows a typical Maven configuration:
[source,xml,indent=0]
.pom.xml
----
<project>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>{spring-boot-version}</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zookeeper-config</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
----
The following example shows a typical Gradle setup:
[source,groovy,indent=0]
.build.gradle
----
plugins {
id 'org.springframework.boot' version ${spring-boot-version}
id 'io.spring.dependency-management' version ${spring-dependency-management-version}
id 'java'
}
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.cloud:spring-cloud-starter-zookeeper-config'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
}
dependencyManagement {
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
}
}
----
WARNING: Depending on the version you are using, you might need to adjust Apache Zookeeper version used in your project.
You can read more about it in the <<spring-cloud-zookeeper-install,Install Zookeeper section>>.
Now you can create a standard Spring Boot application, such as the following HTTP server:
----
@SpringBootApplication
@RestController
public class Application {
@GetMapping("/")
public String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
----
The application retrieves configuration data from Zookeeper.
WARNING: If you use Spring Cloud Zookeeper Config, you need to set the `spring.config.import` property in order to bind to Zookeeper.
You can read more about it in the <<config-data-import,Spring Boot Config Data Import section>>.
== Zookeeper overview
[[zookeeper-overview]]
= Zookeeper overview
ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.
See the
https://zookeeper.apache.org[Zookeeper site] for more information.
Spring Cloud Zookeeper also builds on the https://curator.apache.org[Apache Curator] project, which started life at Netflix.
== Spring Cloud Zookeeper Features
[[spring-cloud-zookeeper-features]]
= Spring Cloud Zookeeper Features
Spring Cloud Zookeeper includes the following features:
* Spring Cloud `DiscoveryClient` implementation (supports Spring Cloud LoadBalancer)
* Zookeeper-based `PropertySource` loaded during the 'bootstrap' phase
== Running the Sample
[[running-the-sample]]
= Running the Sample
. https://zookeeper.apache.org/doc/current/zookeeperStarted.html#sc_Download[Install
zookeeper] (On a mac with homebrew, use `brew install zookeeper`).
@@ -313,11 +45,13 @@ Doing so brings in the required Spring Cloud Maven repositories and Build.
. Run `java -jar spring-cloud-zookeeper-sample/target/spring-cloud-zookeeper-sample-1.2.0.BUILD-SNAPSHOT.jar --server.port=8081`
. Visit http://localhost:8080 again to verify that `{"serviceId":"testZookeeperApp","host":"<yourhost>","port":8081}` eventually shows up in the results in a round-robin fashion. (It may take a minute or so.)
== Building
[[building]]
= Building
:jdkversion: 17
=== Basic Compile and Test
[[basic-compile-and-test]]
== Basic Compile and Test
To build the source you will need to install JDK {jdkversion}.
@@ -344,31 +78,36 @@ source control.
The projects that require middleware (i.e. Redis) for testing generally
require that a local instance of [Docker](https://www.docker.com/get-started) is installed and running.
=== Documentation
[[documentation]]
== Documentation
The spring-cloud-build module has a "docs" profile, and if you switch
that on it will try to build asciidoc sources from
`src/main/asciidoc`. As part of that process it will look for a
`README.adoc` and process it by loading all the includes, but not
that on it will try to build asciidoc sources using https://docs.antora.org/antora/latest/[Antora] from
`modules/ROOT/`.
As part of that process it will look for a
`docs/src/main/asciidoc/README.adoc` and process it by loading all the includes, but not
parsing or rendering it, just copying it to `${main.basedir}`
(defaults to `${basedir}`, i.e. the root of the project). If there are
(defaults to `$\{basedir}`, i.e. the root of the project). If there are
any changes in the README it will then show up after a Maven build as
a modified file in the correct place. Just commit it and push the change.
=== Working with the code
[[working-with-the-code]]
== Working with the code
If you don't have an IDE preference we would recommend that you use
https://www.springsource.com/developer/sts[Spring Tools Suite] or
https://eclipse.org[Eclipse] when working with the code. We use the
https://eclipse.org/m2e/[m2eclipse] eclipse plugin for maven support. Other IDEs and tools
should also work without issue as long as they use Maven 3.3.3 or better.
==== Activate the Spring Maven profile
[[activate-the-spring-maven-profile]]
=== Activate the Spring Maven profile
Spring Cloud projects require the 'spring' Maven profile to be activated to resolve
the spring milestone and snapshot repositories. Use your preferred IDE to set this
profile to be active, or you may experience build errors.
==== Importing into eclipse with m2eclipse
[[importing-into-eclipse-with-m2eclipse]]
=== Importing into eclipse with m2eclipse
We recommend the https://eclipse.org/m2e/[m2eclipse] eclipse plugin when working with
eclipse. If you don't already have m2eclipse installed it is available from the "eclipse
marketplace".
@@ -382,7 +121,8 @@ add the "spring" profile to your `settings.xml`. Alternatively you can
copy the repository settings from the "spring" profile of the parent
pom into your `settings.xml`.
==== Importing into eclipse without m2eclipse
[[importing-into-eclipse-without-m2eclipse]]
=== Importing into eclipse without m2eclipse
If you prefer not to use m2eclipse you can generate eclipse project metadata using the
following command:
@@ -395,17 +135,20 @@ The generated eclipse projects can be imported by selecting `import existing pro
from the `file` menu.
== Contributing
[[contributing]]
= Contributing
:spring-cloud-build-branch: master
:spring-cloud-build-branch: main
Spring Cloud is released under the non-restrictive Apache 2.0 license,
and follows a very standard Github development process, using Github
tracker for issues and merging pull requests into master. If you want
tracker for issues and merging pull requests into main. If you want
to contribute even something trivial please do not hesitate, but
follow the guidelines below.
=== Sign the Contributor License Agreement
[[sign-the-contributor-license-agreement]]
== Sign the Contributor License Agreement
Before we accept a non-trivial patch or pull request we will need you to sign the
https://cla.pivotal.io/sign/spring[Contributor License Agreement].
Signing the contributor's agreement does not grant anyone commit rights to the main
@@ -413,19 +156,21 @@ repository, but it does mean that we can accept your contributions, and you will
author credit if we do. Active contributors might be asked to join the core team, and
given the ability to merge pull requests.
=== Code of Conduct
This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc[code of
[[code-of-conduct]]
== Code of Conduct
This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/main/docs/src/main/asciidoc/code-of-conduct.adoc[code of
conduct]. By participating, you are expected to uphold this code. Please report
unacceptable behavior to spring-code-of-conduct@pivotal.io.
=== Code Conventions and Housekeeping
[[code-conventions-and-housekeeping]]
== Code Conventions and Housekeeping
None of these is essential for a pull request, but they will all help. They can also be
added after the original pull request but before a merge.
* Use the Spring Framework code format conventions. If you use Eclipse
you can import formatter settings using the
`eclipse-code-formatter.xml` file from the
https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
Cloud Build] project. If using IntelliJ, you can use the
https://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter
Plugin] to import the same file.
@@ -438,13 +183,14 @@ added after the original pull request but before a merge.
than cosmetic changes).
* Add some Javadocs and, if you change the namespace, some XSD doc elements.
* A few unit tests would help a lot as well -- someone has to do it.
* If no-one else is using your branch, please rebase it against the current master (or
* If no-one else is using your branch, please rebase it against the current main (or
other target branch in the main project).
* When writing a commit message please follow https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions],
if you are fixing an existing issue please add `Fixes gh-XXXX` at the end of the commit
message (where XXXX is the issue number).
=== Checkstyle
[[checkstyle]]
== Checkstyle
Spring Cloud Build comes with a set of checkstyle rules. You can find them in the `spring-cloud-build-tools` module. The most notable files under the module are:
@@ -462,7 +208,8 @@ Spring Cloud Build comes with a set of checkstyle rules. You can find them in th
<2> File header setup
<3> Default suppression rules
==== Checkstyle configuration
[[checkstyle-configuration]]
=== Checkstyle configuration
Checkstyle rules are *disabled by default*. To add checkstyle to your project just define the following properties and plugins.
@@ -521,16 +268,18 @@ If you need to suppress some rules (e.g. line length needs to be longer), then i
It's advisable to copy the `${spring-cloud-build.rootFolder}/.editorconfig` and `${spring-cloud-build.rootFolder}/.springformat` to your project. That way, some default formatting rules will be applied. You can do so by running this script:
```bash
$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/.editorconfig -o .editorconfig
$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/.editorconfig -o .editorconfig
$ touch .springformat
```
=== IDE setup
[[ide-setup]]
== IDE setup
==== Intellij IDEA
[[intellij-idea]]
=== Intellij IDEA
In order to setup Intellij you should import our coding conventions, inspection profiles and set up the checkstyle plugin.
The following files can be found in the https://github.com/spring-cloud/spring-cloud-build/tree/master/spring-cloud-build-tools[Spring Cloud Build] project.
The following files can be found in the https://github.com/spring-cloud/spring-cloud-build/tree/main/spring-cloud-build-tools[Spring Cloud Build] project.
.spring-cloud-build-tools/
----
@@ -553,13 +302,13 @@ The following files can be found in the https://github.com/spring-cloud/spring-c
.Code style
image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-code-style.png[Code style]
image::intellij-code-style.png[Code style]
Go to `File` -> `Settings` -> `Editor` -> `Code style`. There click on the icon next to the `Scheme` section. There, click on the `Import Scheme` value and pick the `Intellij IDEA code style XML` option. Import the `spring-cloud-build-tools/src/main/resources/intellij/Intellij_Spring_Boot_Java_Conventions.xml` file.
.Inspection profiles
image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-inspections.png[Code style]
image::intellij-inspections.png[Code style]
Go to `File` -> `Settings` -> `Editor` -> `Inspections`. There click on the icon next to the `Profile` section. There, click on the `Import Profile` and import the `spring-cloud-build-tools/src/main/resources/intellij/Intellij_Project_Defaults.xml` file.
@@ -567,21 +316,23 @@ Go to `File` -> `Settings` -> `Editor` -> `Inspections`. There click on the icon
To have Intellij work with Checkstyle, you have to install the `Checkstyle` plugin. It's advisable to also install the `Assertions2Assertj` to automatically convert the JUnit assertions
image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-checkstyle.png[Checkstyle]
image::intellij-checkstyle.png[Checkstyle]
Go to `File` -> `Settings` -> `Other settings` -> `Checkstyle`. There click on the `+` icon in the `Configuration file` section. There, you'll have to define where the checkstyle rules should be picked from. In the image above, we've picked the rules from the cloned Spring Cloud Build repository. However, you can point to the Spring Cloud Build's GitHub repository (e.g. for the `checkstyle.xml` : `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle.xml`). We need to provide the following variables:
Go to `File` -> `Settings` -> `Other settings` -> `Checkstyle`. There click on the `+` icon in the `Configuration file` section. There, you'll have to define where the checkstyle rules should be picked from. In the image above, we've picked the rules from the cloned Spring Cloud Build repository. However, you can point to the Spring Cloud Build's GitHub repository (e.g. for the `checkstyle.xml` : `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/spring-cloud-build-tools/src/main/resources/checkstyle.xml`). We need to provide the following variables:
- `checkstyle.header.file` - please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` URL.
- `checkstyle.suppressions.file` - default suppressions. Please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` URL.
- `checkstyle.header.file` - please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` URL.
- `checkstyle.suppressions.file` - default suppressions. Please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` URL.
- `checkstyle.additional.suppressions.file` - this variable corresponds to suppressions in your local project. E.g. you're working on `spring-cloud-contract`. Then point to the `project-root/src/checkstyle/checkstyle-suppressions.xml` folder. Example for `spring-cloud-contract` would be: `/home/username/spring-cloud-contract/src/checkstyle/checkstyle-suppressions.xml`.
IMPORTANT: Remember to set the `Scan Scope` to `All sources` since we apply checkstyle rules for production and test sources.
=== Duplicate Finder
[[duplicate-finder]]
== Duplicate Finder
Spring Cloud Build brings along the `basepom:duplicate-finder-maven-plugin`, that enables flagging duplicate and conflicting classes and resources on the java classpath.
==== Duplicate Finder configuration
[[duplicate-finder-configuration]]
=== Duplicate Finder configuration
Duplicate finder is *enabled by default* and will run in the `verify` phase of your Maven build, but it will only take effect in your project if you add the `duplicate-finder-maven-plugin` to the `build` section of the projecst's `pom.xml`.

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@@ -0,0 +1,38 @@
antora:
extensions:
- '@springio/antora-extensions/partial-build-extension'
- require: '@springio/antora-extensions/latest-version-extension'
- require: '@springio/antora-extensions/inject-collector-cache-config-extension'
- '@antora/collector-extension'
- '@antora/atlas-extension'
- require: '@springio/antora-extensions/root-component-extension'
root_component_name: 'cloud-zookeeper'
site:
title: Spring Cloud Zookeeper
url: https://docs.spring.io/spring-cloud-zookeeper/reference/
content:
sources:
- url: ./..
branches: HEAD
start_path: docs
worktrees: true
asciidoc:
attributes:
page-stackoverflow-url: https://stackoverflow.com/tags/spring-cloud
page-pagination: ''
hide-uri-scheme: '@'
tabs-sync-option: '@'
chomp: 'all'
extensions:
- '@asciidoctor/tabs'
- '@springio/asciidoctor-extensions'
sourcemap: true
urls:
latest_version_segment: ''
runtime:
log:
failure_level: warn
format: pretty
ui:
bundle:
url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.3.5/ui-bundle.zip

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docs/antora.yml Normal file
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@@ -0,0 +1,12 @@
name: cloud-zookeeper
version: true
title: spring-cloud-zookeeper
nav:
- modules/ROOT/nav.adoc
ext:
collector:
run:
command: ./mvnw --no-transfer-progress -B process-resources -Pdocs -pl docs -Dantora-maven-plugin.phase=none -Dgenerate-docs.phase=none -Dgenerate-readme.phase=none -Dgenerate-cloud-resources.phase=none -Dmaven-dependency-plugin-for-docs.phase=none -Dmaven-dependency-plugin-for-docs-classes.phase=none -DskipTests
local: true
scan:
dir: ./target/classes/antora-resources/

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* xref:index.adoc[]
* xref:quickstart.adoc[]
* xref:install.adoc[]
* xref:discovery.adoc[]
* xref:other-componentes.adoc[]
* xref:service-registry.adoc[]
* xref:dependencies.adoc[]
* xref:dependency-watcher.adoc[]
* xref:config.adoc[]
* xref:appendix.adoc[]

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@@ -2,8 +2,6 @@
:doctype: book
:idprefix:
:idseparator: -
:toc: left
:toclevels: 4
:tabsize: 4
:numbered:
:sectanchors:
@@ -13,4 +11,4 @@
:docinfo: shared,private
:sc-ext: java
:project-full-name: Spring Cloud Zookeeper
:project-full-name: Spring Cloud Zookeeper

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:numbered!:
[appendix]
[[common-application-properties]]
== Common application properties
= Common application properties
:page-section-summary-toc: 1
include::_attributes.adoc[]
Various properties can be specified inside your `application.properties` file, inside your `application.yml` file, or as command line switches.
This appendix provides a list of common {project-full-name} properties and references to the underlying classes that consume them.
This appendix provides a list of common Spring Cloud Zookeeper properties and references to the underlying classes that consume them.
NOTE: Property contributions can come from additional jar files on your classpath, so you should not consider this an exhaustive list.
Also, you can define your own properties.
include::_configprops.adoc[]
include::partial$_configprops.adoc[]

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[[spring-cloud-zookeeper-config]]
= Distributed Configuration with Zookeeper
Zookeeper provides a
https://zookeeper.apache.org/doc/current/zookeeperOver.html#sc_dataModelNameSpace[hierarchical namespace]
that lets clients store arbitrary data, such as configuration data. Spring Cloud Zookeeper
Config is an alternative to the
https://github.com/spring-cloud/spring-cloud-config[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, to mimic the Spring Cloud Config order of resolving properties. For example, an
application with a name of `testApp` and with the `dev` profile has the following property
sources created for it:
* `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` namespace apply to all applications that use
zookeeper for configuration. Properties in the `config/testApp` namespace are available
only to the instances of the service named `testApp`.
Configuration is currently read on startup of the application. Sending a HTTP `POST`
request to `/refresh` causes the configuration to be reloaded. Watching the configuration
namespace (which Zookeeper supports) is not currently implemented.
[[activating]]
== Activating
Including a dependency on
`org.springframework.cloud:spring-cloud-starter-zookeeper-config` enables
autoconfiguration that sets up Spring Cloud Zookeeper Config.
CAUTION: When working with version 3.4 of Zookeeper you need to change
the way you include the dependency as described xref:install.adoc[here].
[[config-data-import]]
== Spring Boot Config Data Import
Spring Boot 2.4 introduced a new way to import configuration data via the `spring.config.import` property. This is now the default way to get configuration from Zookeeper.
To optionally connect to Zookeeper for configuration set the following in application.properties:
.application.properties
[source,properties]
----
spring.config.import=optional:zookeeper:
----
This will connect to Zookeeper at the default location of "localhost:2181". Removing the `optional:` prefix will cause Zookeeper Config to fail if it is unable to connect to Zookeeper. To change the connection properties of Zookeeper Config either set `spring.cloud.zookeeper.connect-string` or add the connect string to the `spring.config.import` statement such as, `spring.config.import=optional:zookeeper:myhost:2818`. The location in the import property has precedence over the `connect-string` property.
Zookeeper Config will try to load values from four automatic contexts based on `spring.cloud.zookeeper.config.name` (which defaults to the value of the `spring.application.name` property) and `spring.cloud.zookeeper.config.default-context` (which defaults to `application`). If you want to specify the contexts rather than using the computed ones, you can add that information to the `spring.config.import` statement.
.application.properties
[source,properties]
----
spring.config.import=optional:zookeeper:myhost:2181/contextone;/context/two
----
This will optionally load configuration only from `/contextone` and `/context/two`.
NOTE: A `bootstrap` file (properties or yaml) is *not* needed for the Spring Boot Config Data method of import via `spring.config.import`.
[[customizing]]
== Customizing
Zookeeper Config may be customized by setting the following properties:
[source,yml,indent=0]
----
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.
CAUTION: If you have set `spring.cloud.bootstrap.enabled=true` or `spring.config.use-legacy-processing=true`, or included `spring-cloud-starter-bootstrap`, then the above values will need to be placed in `bootstrap.yml` instead of `application.yml`.
[[access-control-lists-acls]]
== Access Control Lists (ACLs)
You can add authentication information for Zookeeper ACLs by calling the `addAuthInfo`
method of a `CuratorFramework` bean. One way to accomplish this is to provide your own
`CuratorFramework` bean, as shown in the following example:
[source,java,indent=0]
----
@BoostrapConfiguration
public class CustomCuratorFrameworkConfig {
@Bean
public CuratorFramework curatorFramework() {
CuratorFramework curator = new CuratorFramework();
curator.addAuthInfo("digest", "user:password".getBytes());
return curator;
}
}
----
Consult
https://github.com/spring-cloud/spring-cloud-zookeeper/blob/main/spring-cloud-zookeeper-core/src/main/java/org/springframework/cloud/zookeeper/ZookeeperAutoConfiguration.java[the ZookeeperAutoConfiguration class]
to see how the `CuratorFramework` bean's default configuration.
Alternatively, you can add your credentials from a class that depends on the existing
`CuratorFramework` bean, as shown in the following example:
[source,java,indent=0]
----
@BoostrapConfiguration
public class DefaultCuratorFrameworkConfig {
public ZookeeperConfig(CuratorFramework curator) {
curator.addAuthInfo("digest", "user:password".getBytes());
}
}
----
The creation of this bean 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 that you set as the
value of the `org.springframework.cloud.bootstrap.BootstrapConfiguration` property in the
`resources/META-INF/spring.factories` file, as shown in the following example:
.resources/META-INF/spring.factories
----
org.springframework.cloud.bootstrap.BootstrapConfiguration=\
my.project.CustomCuratorFrameworkConfig,\
my.project.DefaultCuratorFrameworkConfig
----

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[[configuration-properties]]
= Configuration Properties
Below you can find a list of configuration properties.
include::partial$_configprops.adoc[]

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[[spring-cloud-zookeeper-dependencies]]
= Zookeeper Dependencies
The following topics cover how to work with Spring Cloud Zookeeper dependencies:
* xref:dependencies.adoc#spring-cloud-zookeeper-dependencies-using[Using the Zookeeper Dependencies]
* xref:dependencies.adoc#spring-cloud-zookeeper-dependencies-activating[Activating Zookeeper Dependencies]
* xref:dependencies.adoc#spring-cloud-zookeeper-dependencies-setting-up[Setting up Zookeeper Dependencies]
* xref:dependencies.adoc#spring-cloud-zookeeper-dependencies-configuring[Configuring Spring Cloud Zookeeper Dependencies]
[[spring-cloud-zookeeper-dependencies-using]]
== 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 through
https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/[OpenFeign]
(a REST client builder), `RestTemplate` and `WebClient` via https://docs.spring.io/spring-cloud-commons/reference/spring-cloud-commons/loadbalancer.html#spring-cloud-loadbalancer-integrations[Spring Cloud Loadbalancer].
You can also use the Zookeeper Dependency Watchers functionality to control and monitor
the state of your dependencies.
[[spring-cloud-zookeeper-dependencies-activating]]
== Activating Zookeeper Dependencies
Including a dependency on
`org.springframework.cloud:spring-cloud-starter-zookeeper-discovery` enables
autoconfiguration that sets up Spring Cloud Zookeeper Dependencies. Even if you provide
the dependencies in your properties, you can turn off the dependencies. To do so, set the
`spring.cloud.zookeeper.dependency.enabled` property to false (it defaults to `true`).
[[spring-cloud-zookeeper-dependencies-setting-up]]
== Setting up Zookeeper Dependencies
Consider the following example of dependency representation:
[source,yml,indent=0]
.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
----
The next few sections go through each part of the dependency one by one. The root property
name is `spring.cloud.zookeeper.dependencies`.
[[spring-cloud-zookeeper-dependencies-setting-up-aliases]]
=== Aliases
Below the root property you have to represent each dependency as an alias.
This is due to the constraints of Spring Cloud LoadBalancer, which requires that the application ID be placed in the URL.
Consequently, you cannot pass any complex path, suchas `/myApp/myRoute/name`).
The alias is the name you use instead of the `serviceId` for `DiscoveryClient`, `Feign`, or
`RestTemplate`.
In the previous examples, the aliases are `newsletter` and `mailing`.
The following example shows Feign usage with a `newsletter` alias:
[source,java,indent=0]
----
@FeignClient("newsletter")
public interface NewsletterService {
@RequestMapping(method = RequestMethod.GET, value = "/newsletter")
String getNewsletters();
}
----
[[path]]
=== Path
The path is represented by the `path` YAML property and is the path under which the dependency is registered under Zookeeper.
As described in the
xref:dependencies.adoc#spring-cloud-zookeeper-dependencies-setting-up-aliases[previous section], Spring Cloud LoadBalancer operates on URLs.
As a result, this path is not compliant with its requirement.
That is why Spring Cloud Zookeeper maps the alias to the proper path.
[[load-balancer-type]]
=== Load Balancer Type
The load balancer type is represented by `loadBalancerType` YAML property.
If you know what kind of load-balancing strategy has to be applied when calling this particular dependency, you can provide it in the YAML file, and it is automatically applied.
You can choose one of the following load balancing strategies:
* STICKY: Once chosen, the instance is always called.
* RANDOM: Picks an instance randomly.
* ROUND_ROBIN: Iterates over instances over and over again.
[[content-type-template-and-version]]
=== `Content-Type` Template and Version
The `Content-Type` template and version are represented by the `contentTypeTemplate` and
`version` YAML properties.
If you version your API in the `Content-Type` header, you do not want to add this header
to each of your requests. Also, if you want to call a new version of the API, you do not
want to roam around your code to bump up the API version. That is why you can provide a
`contentTypeTemplate` with a special `$version` placeholder. That placeholder will be filled by the value of the
`version` YAML property. Consider the following example of a `contentTypeTemplate`:
----
application/vnd.newsletter.$version+json
----
Further consider the following `version`:
----
v1
----
The combination of `contentTypeTemplate` and version results in the creation of a
`Content-Type` header for each request, as follows:
----
application/vnd.newsletter.v1+json
----
[[default-headers]]
=== Default Headers
Default headers are represented by the `headers` map in YAML.
Sometimes, each call to a dependency requires setting up of some default headers. To not
do that in code, you can set them up in the YAML file, as shown in the following example
`headers` section:
[source,yml,indent=0]
----
headers:
Accept:
- text/html
- application/xhtml+xml
Cache-Control:
- no-cache
----
That `headers` section results in adding the `Accept` and `Cache-Control` headers with
appropriate list of values in your HTTP request.
[[required-dependencies]]
=== Required Dependencies
Required dependencies are represented by `required` property in YAML.
If one of your dependencies is required to be up when your application boots, you can set
the `required: true` property in the YAML file.
If your application cannot localize the required dependency during boot time, it throws an
exception, and the Spring Context fails to set up. In other words, your application cannot
start if the required dependency is not registered in Zookeeper.
You can read more about Spring Cloud Zookeeper Presence Checker
xref:dependency-watcher.adoc#spring-cloud-zookeeper-dependency-watcher-presence-checker[later in this document].
[[stubs]]
=== Stubs
You can provide a colon-separated path to the JAR containing stubs of the dependency, as
shown in the following example:
`stubs: org.springframework:myApp:stubs`
where:
* `org.springframework` is the `groupId`.
* `myApp` is the `artifactId`.
* `stubs` is the classifier. (Note that `stubs` is the default value.)
Because `stubs` is the default classifier, the preceding example is equal to the following
example:
`stubs: org.springframework:myApp`
[[spring-cloud-zookeeper-dependencies-configuring]]
== Configuring Spring Cloud Zookeeper Dependencies
You can set the following properties to enable or disable parts of Zookeeper Dependencies functionalities:
* `spring.cloud.zookeeper.dependencies`: If you do not set this property, you cannot use Zookeeper Dependencies.
* `spring.cloud.zookeeper.dependency.loadbalancer.enabled` (enabled by default): Turns on Zookeeper-specific custom load-balancing strategies, including `ZookeeperServiceInstanceListSupplier` and dependency-based load-balanced `RestTemplate` setup.
* `spring.cloud.zookeeper.dependency.headers.enabled` (enabled by default): This property registers a `FeignBlockingLoadBalancerClient` that automatically appends appropriate headers and content types with their versions, as presented in the Dependency configuration.
Without this setting, those two parameters do not work.
* `spring.cloud.zookeeper.dependency.resttemplate.enabled` (enabled by default): When enabled, this property modifies the request headers of a `@LoadBalanced`-annotated
`RestTemplate` such that it passes headers and content type with the version set in dependency configuration.
Without this setting, those two parameters do not work.

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[[spring-cloud-zookeeper-dependency-watcher]]
= Spring Cloud Zookeeper Dependency Watcher
The Dependency Watcher mechanism lets you register listeners to your dependencies. The
functionality is, in fact, an implementation of the `Observator` pattern. When a
dependency changes, its state (to either UP or DOWN), some custom logic can be applied.
[[activating]]
== Activating
Spring Cloud Zookeeper Dependencies functionality needs to be enabled for you to use the
Dependency Watcher mechanism.
// TODO: How can the reader do that?
[[registering-a-listener]]
== Registering a Listener
To register a listener, you must implement an interface called
`org.springframework.cloud.zookeeper.discovery.watcher.DependencyWatcherListener` and
register it as a bean. The interface gives you one method:
[source,java,indent=0]
----
void stateChanged(String dependencyName, DependencyState newState);
----
If you want to register a listener for a particular dependency, the `dependencyName` would
be the discriminator for your concrete implementation. `newState` provides you with
information about whether your dependency has changed to `CONNECTED` or `DISCONNECTED`.
[[spring-cloud-zookeeper-dependency-watcher-presence-checker]]
== Using the Presence Checker
Bound with the Dependency Watcher is the functionality called Presence Checker. It lets
you provide custom behavior when your application boots, to react according 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 is not in Zookeeper, when your application
boots, it throws an exception and shuts down.
. If the dependency is not `required`, the
`org.springframework.cloud.zookeeper.discovery.watcher.presence.LogMissingDependencyChecker`
logs that the dependency is missing at the `WARN` level.
Because the `DefaultDependencyPresenceOnStartupVerifier` is registered only when there is
no bean of type `DependencyPresenceOnStartupVerifier`, this functionality can be
overridden.

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[[spring-cloud-zookeeper-discovery]]
= 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 difficult to do and can be
brittle. https://curator.apache.org[Curator](A Java library for Zookeeper) provides Service
Discovery through a https://curator.apache.org/curator-x-discovery/[Service Discovery
Extension]. Spring Cloud Zookeeper uses this extension for service registration and
discovery.
[[activating]]
== Activating
Including a dependency on
`org.springframework.cloud:spring-cloud-starter-zookeeper-discovery` enables
autoconfiguration that sets up Spring Cloud Zookeeper Discovery.
NOTE: For web functionality, you still need to include
`org.springframework.boot:spring-boot-starter-web`.
CAUTION: When working with version 3.4 of Zookeeper you need to change
the way you include the dependency as described xref:install.adoc[here].
[[registering-with-zookeeper]]
== Registering with Zookeeper
When a client registers with Zookeeper, it provides metadata (such as host and port, ID,
and name) about itself.
The following example shows a Zookeeper client:
[source,java,indent=0]
----
@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);
}
}
----
NOTE: The preceding example is a normal Spring Boot application.
If Zookeeper is located somewhere other than `localhost:2181`, the configuration must
provide the location of the server, as shown in the following example:
[source,yml,indent=0]
.application.yml
----
spring:
cloud:
zookeeper:
connect-string: localhost:2181
----
CAUTION: If you use xref:config.adoc[Spring Cloud Zookeeper Config], the
values shown in the preceding example need to be 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`" (that is, it registers itself) and a "`client`" (that is, 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]]
== Using the DiscoveryClient
Spring Cloud has support for
https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/[OpenFeign]
(a REST client builder), `RestTemplate` and `WebClient` via https://docs.spring.io/spring-cloud-commons/reference/spring-cloud-commons/loadbalancer.html#spring-cloud-loadbalancer-integrations[Spring Cloud Loadbalancer], using 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, as shown in
the following example:
[source,java,indent=0]
----
@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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include::intro.adoc[]

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[[spring-cloud-zookeeper-install]]
= Working with Zookeeper
See the https://zookeeper.apache.org/doc/current/zookeeperStarted.html[installation
documentation] for instructions on how to install Zookeeper.
// TODO: describe Testcontainers and zk

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@@ -1,5 +1,5 @@
include::_attributes.adoc[]
[[spring-cloud-gateway-intro]]
= Introduction
This project provides Zookeeper integrations for Spring Boot applications through
autoconfiguration and binding to the Spring Environment and other Spring programming model

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[[spring-cloud-zookeeper-other-componentes]]
= Using Spring Cloud Zookeeper with Spring Cloud Components
:page-section-summary-toc: 1
Feign, Spring Cloud Gateway and Spring Cloud LoadBalancer all work with Spring Cloud Zookeeper.
[[spring-cloud-loadbalancer-with-zookeeper]]
== Spring Cloud LoadBalancer with Zookeeper
Spring Cloud Zookeeper provides an implementation of Spring Cloud LoadBalancer `ServiceInstanceListSupplier`.
When you use the `spring-cloud-starter-zookeeper-discovery`, Spring Cloud LoadBalancer is autoconfigured to use the
`ZookeeperServiceInstanceListSupplier` by default.
TIP: If you were previously using the StickyRule in Zookeeper, its replacement in the current stack
is the `SameInstancePreferenceServiceInstanceListSupplier` in SC LoadBalancer. You can read on how to set it up in the https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#spring-cloud-loadbalancer[Spring Cloud Commons documentation].

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@@ -1,8 +1,12 @@
[[quick-start]]
= Quick Start
This quick start walks through using Spring Cloud Zookeeper for Service Discovery and Distributed Configuration.
First, run Zookeeper on your machine. Then you can access it and use it as a Service Registry and Configuration source with Spring Cloud Zookeeper.
=== Discovery Client Usage
[[discovery-client-usage]]
== Discovery Client Usage
To use these features in an application, you can build it as a Spring Boot application that depends on `spring-cloud-zookeeper-core` and `spring-cloud-zookeeper-discovery`.
The most convenient way to add the dependency is with a Spring Boot starter: `org.springframework.cloud:spring-cloud-starter-zookeeper-discovery`.
@@ -80,7 +84,7 @@ dependencyManagement {
----
WARNING: Depending on the version you are using, you might need to adjust Apache Zookeeper version used in your project.
You can read more about it in the <<spring-cloud-zookeeper-install,Install Zookeeper section>>.
You can read more about it in the xref:install.adoc[Install Zookeeper section].
Now you can create a standard Spring Boot application, such as the following HTTP server:
@@ -127,7 +131,8 @@ public String serviceUrl() {
}
----
=== Distributed Configuration Usage
[[distributed-configuration-usage]]
== Distributed Configuration Usage
To use these features in an application, you can build it as a Spring Boot application that depends on `spring-cloud-zookeeper-core` and `spring-cloud-zookeeper-config`.
The most convenient way to add the dependency is with a Spring Boot starter: `org.springframework.cloud:spring-cloud-starter-zookeeper-config`.
@@ -205,7 +210,7 @@ dependencyManagement {
----
WARNING: Depending on the version you are using, you might need to adjust Apache Zookeeper version used in your project.
You can read more about it in the <<spring-cloud-zookeeper-install,Install Zookeeper section>>.
You can read more about it in the xref:install.adoc[Install Zookeeper section].
Now you can create a standard Spring Boot application, such as the following HTTP server:
@@ -229,4 +234,4 @@ public class Application {
The application retrieves configuration data from Zookeeper.
WARNING: If you use Spring Cloud Zookeeper Config, you need to set the `spring.config.import` property in order to bind to Zookeeper.
You can read more about it in the <<config-data-import,Spring Boot Config Data Import section>>.
You can read more about it in the xref:config.adoc#config-data-import[Spring Boot Config Data Import section].

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[[spring-cloud-zookeeper-service-registry]]
= Spring Cloud Zookeeper and Service Registry
Spring Cloud Zookeeper implements the `ServiceRegistry` interface, letting developers
register arbitrary services in a programmatic way.
The `ServiceInstanceRegistration` class offers a `builder()` method to create a
`Registration` object that can be used by the `ServiceRegistry`, as shown in the following
example:
[source,java,indent=0]
----
@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]]
== Instance Status
Netflix Eureka supports having instances that are `OUT_OF_SERVICE` registered with the server.
These instances are not returned as active service instances.
This is useful for behaviors such as blue/green deployments.
(Note that 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 Spring Cloud LoadBalancer `ZookeeperServiceInstanceListSupplier`.
The `ZookeeperServiceInstanceListSupplier` filters out all non-null instance statuses that do not equal `UP`.
If the instance status field is empty, it is considered to be `UP` for backwards compatibility.
To change the status of an instance, make a `POST` with `OUT_OF_SERVICE` to the `ServiceRegistry`
instance status actuator endpoint, as shown in the following example:
[source,sh,indent=0]
----
$ http POST http://localhost:8081/service-registry status=OUT_OF_SERVICE
----
NOTE: The preceding example uses the `http` command from https://httpie.org.

0
docs/src/main/asciidoc/_configprops.adoc → docs/modules/ROOT/partials/_configprops.adoc
View File

36
docs/pom.xml
View File

@@ -1,25 +1,30 @@
<?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"
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://maven.apache.org/POM/4.0.0"
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>
<parent>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-zookeeper</artifactId>
<version>4.1.0-SNAPSHOT</version>
<relativePath>..</relativePath>
</parent>
<artifactId>spring-cloud-zookeeper-docs</artifactId>
<packaging>jar</packaging>
<name>Spring Cloud Zookeeper Docs</name>
<description>Spring Cloud Docs</description>
<description>Spring Cloud Zookeeper Docs</description>
<properties>
<docs.main>spring-cloud-zookeeper</docs.main>
<main.basedir>${basedir}/..</main.basedir>
<configprops.inclusionPattern>spring.cloud.zookeeper.*|
</configprops.inclusionPattern>
<upload-docs-zip.phase>deploy</upload-docs-zip.phase>
<configprops.inclusionPattern>spring.cloud.zookeeper.*</configprops.inclusionPattern>
<!-- Don't upload docs jar to central / repo.spring.io -->
<maven-deploy-plugin-default.phase>none</maven-deploy-plugin-default.phase>
<!-- Observability -->
<micrometer-docs-generator.version>1.0.2</micrometer-docs-generator.version>
<micrometer-docs-generator.inputPath>${maven.multiModuleProjectDirectory}/</micrometer-docs-generator.inputPath>
<micrometer-docs-generator.inclusionPattern>.*</micrometer-docs-generator.inclusionPattern>
<micrometer-docs-generator.outputPath>${maven.multiModuleProjectDirectory}/docs/modules/ROOT/partials/</micrometer-docs-generator.outputPath>
</properties>
<dependencies>
<dependency>
@@ -34,26 +39,35 @@
<profile>
<id>docs</id>
<build>
<resources>
<resource>
<directory>src/main/antora/resources/antora-resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>pl.project13.maven</groupId>
<artifactId>git-commit-id-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-resources-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.asciidoctor</groupId>
<artifactId>asciidoctor-maven-plugin</artifactId>
<groupId>io.spring.maven.antora</groupId>
<artifactId>antora-component-version-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>io.spring.maven.antora</groupId>
<artifactId>antora-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
</plugin>
<plugin>

20
docs/src/main/antora/resources/antora-resources/antora.yml Normal file
View File

@@ -0,0 +1,20 @@
version: @antora-component.version@
prerelease: @antora-component.prerelease@
asciidoc:
attributes:
attribute-missing: 'warn'
chomp: 'all'
project-root: @maven.multiModuleProjectDirectory@
github-repo: @docs.main@
github-raw: https://raw.githubusercontent.com/spring-cloud/@docs.main@/@github-tag@
github-code: https://github.com/spring-cloud/@docs.main@/tree/@github-tag@
github-issues: https://github.com/spring-cloud/@docs.main@/issues/
github-wiki: https://github.com/spring-cloud/@docs.main@/wiki
spring-cloud-version: @project.version@
github-tag: @github-tag@
version-type: @version-type@
docs-url: https://docs.spring.io/@docs.main@/docs/@project.version@
raw-docs-url: https://raw.githubusercontent.com/spring-cloud/@docs.main@/@github-tag@
project-version: @project.version@
project-name: @docs.main@

27
docs/src/main/asciidoc/README.adoc
View File

@@ -1,28 +1,29 @@
image::https://travis-ci.org/spring-cloud/spring-cloud-zookeeper.svg?branch=master[Build Status, link=https://travis-ci.org/spring-cloud/spring-cloud-zookeeper]
image::https://github.com/spring-cloud/spring-cloud-zookeeper/workflows/Build/badge.svg?style=svg["Actions Status", link="https://github.com/spring-cloud/spring-cloud-zookeeper/actions"]
include::intro.adoc[]
include::_attributes.adoc[]
== Quick Start
[[quick-start]]
= Quick Start
include::quickstart.adoc[]
== Zookeeper overview
[[zookeeper-overview]]
= Zookeeper overview
ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.
See the
https://zookeeper.apache.org[Zookeeper site] for more information.
Spring Cloud Zookeeper also builds on the https://curator.apache.org[Apache Curator] project, which started life at Netflix.
== Spring Cloud Zookeeper Features
[[spring-cloud-zookeeper-features]]
= Spring Cloud Zookeeper Features
Spring Cloud Zookeeper includes the following features:
* Spring Cloud `DiscoveryClient` implementation (supports Spring Cloud LoadBalancer)
* Zookeeper-based `PropertySource` loaded during the 'bootstrap' phase
== Running the Sample
[[running-the-sample]]
= Running the Sample
. https://zookeeper.apache.org/doc/current/zookeeperStarted.html#sc_Download[Install
zookeeper] (On a mac with homebrew, use `brew install zookeeper`).
@@ -37,10 +38,12 @@ Doing so brings in the required Spring Cloud Maven repositories and Build.
. Run `java -jar spring-cloud-zookeeper-sample/target/spring-cloud-zookeeper-sample-1.2.0.BUILD-SNAPSHOT.jar --server.port=8081`
. Visit http://localhost:8080 again to verify that `{"serviceId":"testZookeeperApp","host":"<yourhost>","port":8081}` eventually shows up in the results in a round-robin fashion. (It may take a minute or so.)
== Building
[[building]]
= Building
include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/building.adoc[]
include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/docs/modules/ROOT/partials/building.adoc[]
== Contributing
[[contributing]]
= Contributing
include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/contributing.adoc[]
include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/docs/modules/ROOT/partials/contributing.adoc[]

1
docs/src/main/asciidoc/index.adoc
View File

@@ -1 +0,0 @@
include::spring-cloud-zookeeper.adoc[]

2
docs/src/main/asciidoc/sagan-boot.adoc
View File

@@ -1,2 +0,0 @@
include::_attributes.adoc[]

39
docs/src/main/asciidoc/sagan-index.adoc
View File

@@ -1,39 +0,0 @@
include::_attributes.adoc[]
Spring Cloud Zookeeper provides http://zookeeper.apache.org/[Apache 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. The patterns provided include Service Discovery and Distributed Configuration.
## Features
* Service Discovery: instances can be registered with Zookeeper and clients can discover the instances using Spring-managed beans
* Supports Spring Cloud LoadBalancer - client-side load-balancing solution
* Supports Spring Cloud OpenFeign
* Distributed Configuration: using Zookeeper as a data store
## Quick Start
As long as Spring Cloud Zookeeper, http://curator.apache.org/[Apache Curator] and the Zookeeper Java Client are on the
classpath any Spring Boot application with `@EnableDiscoveryClient` will try to contact a Zookeeper
agent on `localhost:2181` (the default value of
`zookeeper.connectString`).
```java
@Configuration
@EnableAutoConfiguration
@EnableDiscoveryClient
@RestController
public class Application {
@RequestMapping("/")
public String home() {
return "Hello World";
}
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
```
A local Zookeeper server must be running. See the http://zookeeper.apache.org/[Zookeeper documentation] on how to run a Zookeeper server.

617
docs/src/main/asciidoc/spring-cloud-zookeeper.adoc
View File

@@ -1,617 +0,0 @@
= Spring Cloud Zookeeper
include::intro.adoc[]
include::_attributes.adoc[]
== Quick Start
include::quickstart.adoc[]
[[spring-cloud-zookeeper-install]]
== Install Zookeeper
See the https://zookeeper.apache.org/doc/current/zookeeperStarted.html[installation
documentation] for instructions on how to install Zookeeper.
Spring Cloud Zookeeper uses Apache Curator behind the scenes.
While Zookeeper 3.5.x is still considered "beta" by the Zookeeper development team,
the reality is that it is used in production by many users.
However, Zookeeper 3.4.x is also used in production.
Prior to Apache Curator 4.0, both versions of Zookeeper were supported via two versions of Apache Curator.
Starting with Curator 4.0 both versions of Zookeeper are supported via the same Curator libraries.
In case you are integrating with version 3.4 you need to change the Zookeeper dependency
that comes shipped with `curator`, and thus `spring-cloud-zookeeper`.
To do so simply exclude that dependency and add the 3.4.x version like shown below.
.maven
[source,xml,indent=0]
----
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zookeeper-all</artifactId>
<exclusions>
<exclusion>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.12</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
----
.gradle
[source,groovy,indent=0]
----
compile('org.springframework.cloud:spring-cloud-starter-zookeeper-all') {
exclude group: 'org.apache.zookeeper', module: 'zookeeper'
}
compile('org.apache.zookeeper:zookeeper:3.4.12') {
exclude group: 'org.slf4j', module: 'slf4j-log4j12'
}
----
[[spring-cloud-zookeeper-discovery]]
== 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 difficult to do and can be
brittle. https://curator.apache.org[Curator](A Java library for Zookeeper) provides Service
Discovery through a https://curator.apache.org/curator-x-discovery/[Service Discovery
Extension]. Spring Cloud Zookeeper uses this extension for service registration and
discovery.
=== Activating
Including a dependency on
`org.springframework.cloud:spring-cloud-starter-zookeeper-discovery` enables
autoconfiguration that sets up Spring Cloud Zookeeper Discovery.
NOTE: For web functionality, you still need to include
`org.springframework.boot:spring-boot-starter-web`.
CAUTION: When working with version 3.4 of Zookeeper you need to change
the way you include the dependency as described <<spring-cloud-zookeeper-install,here>>.
=== Registering with Zookeeper
When a client registers with Zookeeper, it provides metadata (such as host and port, ID,
and name) about itself.
The following example shows a Zookeeper client:
[source,java,indent=0]
----
@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);
}
}
----
NOTE: The preceding example is a normal Spring Boot application.
If Zookeeper is located somewhere other than `localhost:2181`, the configuration must
provide the location of the server, as shown in the following example:
[source,yml,indent=0]
.application.yml
----
spring:
cloud:
zookeeper:
connect-string: localhost:2181
----
CAUTION: If you use <<spring-cloud-zookeeper-config,Spring Cloud Zookeeper Config>>, the
values shown in the preceding example need to be 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`" (that is, it registers itself) and a "`client`" (that is, 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
https://github.com/spring-cloud/spring-cloud-netflix/blob/master/docs/src/main/asciidoc/spring-cloud-netflix.adoc#spring-cloud-feign[Feign]
(a REST client builder),
https://github.com/spring-cloud/spring-cloud-netflix/blob/master/docs/src/main/ascii[Spring
`RestTemplate`] and
https://cloud.spring.io/spring-cloud-commons/reference/html/#loadbalanced-webclient[Spring WebFlux], using 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, as shown in
the following example:
[source,java,indent=0]
----
@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;
}
----
[[spring-cloud-zookeeper-other-componentes]]
== Using Spring Cloud Zookeeper with Spring Cloud Components
Feign, Spring Cloud Gateway and Spring Cloud LoadBalancer all work with Spring Cloud Zookeeper.
=== Spring Cloud LoadBalancer with Zookeeper
Spring Cloud Zookeeper provides an implementation of Spring Cloud LoadBalancer `ServiceInstanceListSupplier`.
When you use the `spring-cloud-starter-zookeeper-discovery`, Spring Cloud LoadBalancer is autoconfigured to use the
`ZookeeperServiceInstanceListSupplier` by default.
TIP: If you were previously using the StickyRule in Zookeeper, its replacement in the current stack
is the `SameInstancePreferenceServiceInstanceListSupplier` in SC LoadBalancer. You can read on how to set it up in the https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#spring-cloud-loadbalancer[Spring Cloud Commons documentation].
[[spring-cloud-zookeeper-service-registry]]
== Spring Cloud Zookeeper and Service Registry
Spring Cloud Zookeeper implements the `ServiceRegistry` interface, letting developers
register arbitrary services in a programmatic way.
The `ServiceInstanceRegistration` class offers a `builder()` method to create a
`Registration` object that can be used by the `ServiceRegistry`, as shown in the following
example:
[source,java,indent=0]
----
@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 that are `OUT_OF_SERVICE` registered with the server.
These instances are not returned as active service instances.
This is useful for behaviors such as blue/green deployments.
(Note that 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 Spring Cloud LoadBalancer `ZookeeperServiceInstanceListSupplier`.
The `ZookeeperServiceInstanceListSupplier` filters out all non-null instance statuses that do not equal `UP`.
If the instance status field is empty, it is considered to be `UP` for backwards compatibility.
To change the status of an instance, make a `POST` with `OUT_OF_SERVICE` to the `ServiceRegistry`
instance status actuator endpoint, as shown in the following example:
[source,sh,indent=0]
----
$ http POST http://localhost:8081/service-registry status=OUT_OF_SERVICE
----
NOTE: The preceding example uses the `http` command from https://httpie.org.
[[spring-cloud-zookeeper-dependencies]]
== Zookeeper Dependencies
The following topics cover how to work with Spring Cloud Zookeeper dependencies:
* <<spring-cloud-zookeeper-dependencies-using>>
* <<spring-cloud-zookeeper-dependencies-activating>>
* <<spring-cloud-zookeeper-dependencies-setting-up>>
* <<spring-cloud-zookeeper-dependencies-configuring>>
[[spring-cloud-zookeeper-dependencies-using]]
=== 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 through
https://github.com/spring-cloud/spring-cloud-netflix/blob/master/docs/src/main/asciidoc/spring-cloud-netflix.adoc#spring-cloud-feign[Feign]
(a REST client builder),
https://github.com/spring-cloud/spring-cloud-netflix/blob/master/docs/src/main/ascii[Spring
`RestTemplate`] and
https://cloud.spring.io/spring-cloud-commons/reference/html/#loadbalanced-webclient[Spring WebFlux].
You can also use the Zookeeper Dependency Watchers functionality to control and monitor
the state of your dependencies.
[[spring-cloud-zookeeper-dependencies-activating]]
=== Activating Zookeeper Dependencies
Including a dependency on
`org.springframework.cloud:spring-cloud-starter-zookeeper-discovery` enables
autoconfiguration that sets up Spring Cloud Zookeeper Dependencies. Even if you provide
the dependencies in your properties, you can turn off the dependencies. To do so, set the
`spring.cloud.zookeeper.dependency.enabled` property to false (it defaults to `true`).
[[spring-cloud-zookeeper-dependencies-setting-up]]
=== Setting up Zookeeper Dependencies
Consider the following example of dependency representation:
[source,yml,indent=0]
.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
----
The next few sections go through each part of the dependency one by one. The root property
name is `spring.cloud.zookeeper.dependencies`.
[[spring-cloud-zookeeper-dependencies-setting-up-aliases]]
==== Aliases
Below the root property you have to represent each dependency as an alias.
This is due to the constraints of Spring Cloud LoadBalancer, which requires that the application ID be placed in the URL.
Consequently, you cannot pass any complex path, suchas `/myApp/myRoute/name`).
The alias is the name you use instead of the `serviceId` for `DiscoveryClient`, `Feign`, or
`RestTemplate`.
In the previous examples, the aliases are `newsletter` and `mailing`.
The following example shows Feign usage with a `newsletter` alias:
[source,java,indent=0]
----
@FeignClient("newsletter")
public interface NewsletterService {
@RequestMapping(method = RequestMethod.GET, value = "/newsletter")
String getNewsletters();
}
----
==== Path
The path is represented by the `path` YAML property and is the path under which the dependency is registered under Zookeeper.
As described in the
<<spring-cloud-zookeeper-dependencies-setting-up-aliases,previous section>>, Spring Cloud LoadBalancer operates on URLs.
As a result, this path is not compliant with its requirement.
That is why Spring Cloud Zookeeper maps the alias to the proper path.
==== Load Balancer Type
The load balancer type is represented by `loadBalancerType` YAML property.
If you know what kind of load-balancing strategy has to be applied when calling this particular dependency, you can provide it in the YAML file, and it is automatically applied.
You can choose one of the following load balancing strategies:
* STICKY: Once chosen, the instance is always called.
* RANDOM: Picks an instance randomly.
* ROUND_ROBIN: Iterates over instances over and over again.
==== `Content-Type` Template and Version
The `Content-Type` template and version are represented by the `contentTypeTemplate` and
`version` YAML properties.
If you version your API in the `Content-Type` header, you do not want to add this header
to each of your requests. Also, if you want to call a new version of the API, you do not
want to roam around your code to bump up the API version. That is why you can provide a
`contentTypeTemplate` with a special `$version` placeholder. That placeholder will be filled by the value of the
`version` YAML property. Consider the following example of a `contentTypeTemplate`:
----
application/vnd.newsletter.$version+json
----
Further consider the following `version`:
----
v1
----
The combination of `contentTypeTemplate` and version results in the creation of a
`Content-Type` header for each request, as follows:
----
application/vnd.newsletter.v1+json
----
==== Default Headers
Default headers are represented by the `headers` map in YAML.
Sometimes, each call to a dependency requires setting up of some default headers. To not
do that in code, you can set them up in the YAML file, as shown in the following example
`headers` section:
[source,yml,indent=0]
----
headers:
Accept:
- text/html
- application/xhtml+xml
Cache-Control:
- no-cache
----
That `headers` section results in adding the `Accept` and `Cache-Control` headers with
appropriate list of values in your HTTP request.
==== Required Dependencies
Required dependencies are represented by `required` property in YAML.
If one of your dependencies is required to be up when your application boots, you can set
the `required: true` property in the YAML file.
If your application cannot localize the required dependency during boot time, it throws an
exception, and the Spring Context fails to set up. In other words, your application cannot
start if the required dependency is not registered in Zookeeper.
You can read more about Spring Cloud Zookeeper Presence Checker
<<spring-cloud-zookeeper-dependency-watcher-presence-checker,later in this document>>.
==== Stubs
You can provide a colon-separated path to the JAR containing stubs of the dependency, as
shown in the following example:
`stubs: org.springframework:myApp:stubs`
where:
* `org.springframework` is the `groupId`.
* `myApp` is the `artifactId`.
* `stubs` is the classifier. (Note that `stubs` is the default value.)
Because `stubs` is the default classifier, the preceding example is equal to the following
example:
`stubs: org.springframework:myApp`
[[spring-cloud-zookeeper-dependencies-configuring]]
=== Configuring Spring Cloud Zookeeper Dependencies
You can set the following properties to enable or disable parts of Zookeeper Dependencies functionalities:
* `spring.cloud.zookeeper.dependencies`: If you do not set this property, you cannot use Zookeeper Dependencies.
* `spring.cloud.zookeeper.dependency.loadbalancer.enabled` (enabled by default): Turns on Zookeeper-specific custom load-balancing strategies, including `ZookeeperServiceInstanceListSupplier` and dependency-based load-balanced `RestTemplate` setup.
* `spring.cloud.zookeeper.dependency.headers.enabled` (enabled by default): This property registers a `FeignBlockingLoadBalancerClient` that automatically appends appropriate headers and content types with their versions, as presented in the Dependency configuration.
Without this setting, those two parameters do not work.
* `spring.cloud.zookeeper.dependency.resttemplate.enabled` (enabled by default): When enabled, this property modifies the request headers of a `@LoadBalanced`-annotated
`RestTemplate` such that it passes headers and content type with the version set in dependency configuration.
Without this setting, those two parameters do not work.
[[spring-cloud-zookeeper-dependency-watcher]]
== Spring Cloud Zookeeper Dependency Watcher
The Dependency Watcher mechanism lets you register listeners to your dependencies. The
functionality is, in fact, an implementation of the `Observator` pattern. When a
dependency changes, its state (to either UP or DOWN), some custom logic can be applied.
=== Activating
Spring Cloud Zookeeper Dependencies functionality needs to be enabled for you to use the
Dependency Watcher mechanism.
// TODO: How can the reader do that?
=== Registering a Listener
To register a listener, you must implement an interface called
`org.springframework.cloud.zookeeper.discovery.watcher.DependencyWatcherListener` and
register it as a bean. The interface gives you one method:
[source,java,indent=0]
----
void stateChanged(String dependencyName, DependencyState newState);
----
If you want to register a listener for a particular dependency, the `dependencyName` would
be the discriminator for your concrete implementation. `newState` provides you with
information about whether your dependency has changed to `CONNECTED` or `DISCONNECTED`.
[[spring-cloud-zookeeper-dependency-watcher-presence-checker]]
=== Using the Presence Checker
Bound with the Dependency Watcher is the functionality called Presence Checker. It lets
you provide custom behavior when your application boots, to react according 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 is not in Zookeeper, when your application
boots, it throws an exception and shuts down.
. If the dependency is not `required`, the
`org.springframework.cloud.zookeeper.discovery.watcher.presence.LogMissingDependencyChecker`
logs that the dependency is missing at the `WARN` level.
Because the `DefaultDependencyPresenceOnStartupVerifier` is registered only when there is
no bean of type `DependencyPresenceOnStartupVerifier`, this functionality can be
overridden.
[[spring-cloud-zookeeper-config]]
== Distributed Configuration with Zookeeper
Zookeeper provides a
https://zookeeper.apache.org/doc/current/zookeeperOver.html#sc_dataModelNameSpace[hierarchical namespace]
that lets clients store arbitrary data, such as configuration data. Spring Cloud Zookeeper
Config is an alternative to the
https://github.com/spring-cloud/spring-cloud-config[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, to mimic the Spring Cloud Config order of resolving properties. For example, an
application with a name of `testApp` and with the `dev` profile has the following property
sources created for it:
* `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` namespace apply to all applications that use
zookeeper for configuration. Properties in the `config/testApp` namespace are available
only to the instances of the service named `testApp`.
Configuration is currently read on startup of the application. Sending a HTTP `POST`
request to `/refresh` causes the configuration to be reloaded. Watching the configuration
namespace (which Zookeeper supports) is not currently implemented.
=== Activating
Including a dependency on
`org.springframework.cloud:spring-cloud-starter-zookeeper-config` enables
autoconfiguration that sets up Spring Cloud Zookeeper Config.
CAUTION: When working with version 3.4 of Zookeeper you need to change
the way you include the dependency as described <<spring-cloud-zookeeper-install,here>>.
[[config-data-import]]
=== Spring Boot Config Data Import
Spring Boot 2.4 introduced a new way to import configuration data via the `spring.config.import` property. This is now the default way to get configuration from Zookeeper.
To optionally connect to Zookeeper for configuration set the following in application.properties:
.application.properties
[source,properties]
----
spring.config.import=optional:zookeeper:
----
This will connect to Zookeeper at the default location of "localhost:2181". Removing the `optional:` prefix will cause Zookeeper Config to fail if it is unable to connect to Zookeeper. To change the connection properties of Zookeeper Config either set `spring.cloud.zookeeper.connect-string` or add the connect string to the `spring.config.import` statement such as, `spring.config.import=optional:zookeeper:myhost:2818`. The location in the import property has precedence over the `connect-string` property.
Zookeeper Config will try to load values from four automatic contexts based on `spring.cloud.zookeeper.config.name` (which defaults to the value of the `spring.application.name` property) and `spring.cloud.zookeeper.config.default-context` (which defaults to `application`). If you want to specify the contexts rather than using the computed ones, you can add that information to the `spring.config.import` statement.
.application.properties
[source,properties]
----
spring.config.import=optional:zookeeper:myhost:2181/contextone;/context/two
----
This will optionally load configuration only from `/contextone` and `/context/two`.
NOTE: A `bootstrap` file (properties or yaml) is *not* needed for the Spring Boot Config Data method of import via `spring.config.import`.
=== Customizing
Zookeeper Config may be customized by setting the following properties:
[source,yml,indent=0]
----
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.
CAUTION: If you have set `spring.cloud.bootstrap.enabled=true` or `spring.config.use-legacy-processing=true`, or included `spring-cloud-starter-bootstrap`, then the above values will need to be placed in `bootstrap.yml` instead of `application.yml`.
=== Access Control Lists (ACLs)
You can add authentication information for Zookeeper ACLs by calling the `addAuthInfo`
method of a `CuratorFramework` bean. One way to accomplish this is to provide your own
`CuratorFramework` bean, as shown in the following example:
[source,java,indent=0]
----
@BoostrapConfiguration
public class CustomCuratorFrameworkConfig {
@Bean
public CuratorFramework curatorFramework() {
CuratorFramework curator = new CuratorFramework();
curator.addAuthInfo("digest", "user:password".getBytes());
return curator;
}
}
----
Consult
https://github.com/spring-cloud/spring-cloud-zookeeper/blob/master/spring-cloud-zookeeper-core/src/main/java/org/springframework/cloud/zookeeper/ZookeeperAutoConfiguration.java[the ZookeeperAutoConfiguration class]
to see how the `CuratorFramework` bean's default configuration.
Alternatively, you can add your credentials from a class that depends on the existing
`CuratorFramework` bean, as shown in the following example:
[source,java,indent=0]
----
@BoostrapConfiguration
public class DefaultCuratorFrameworkConfig {
public ZookeeperConfig(CuratorFramework curator) {
curator.addAuthInfo("digest", "user:password".getBytes());
}
}
----
The creation of this bean 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 that you set as the
value of the `org.springframework.cloud.bootstrap.BootstrapConfiguration` property in the
`resources/META-INF/spring.factories` file, as shown in the following example:
.resources/META-INF/spring.factories
----
org.springframework.cloud.bootstrap.BootstrapConfiguration=\
my.project.CustomCuratorFrameworkConfig,\
my.project.DefaultCuratorFrameworkConfig
----