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<body class="book toc2 toc-left">
<div id="header">
<h1>Spring Cloud Kubernetes</h1>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_why_do_you_need_spring_cloud_kubernetes">Why do you need Spring Cloud Kubernetes?</a></li>
<li><a href="#_starters">Starters</a></li>
<li><a href="#_discoveryclient_for_kubernetes">DiscoveryClient for Kubernetes</a></li>
<li><a href="#_kubernetes_native_service_discovery">Kubernetes native service discovery</a></li>
<li><a href="#_kubernetes_propertysource_implementations">Kubernetes PropertySource implementations</a>
<ul class="sectlevel2">
<li><a href="#configmap-propertysource">Using a <code>ConfigMap</code> <code>PropertySource</code></a></li>
<li><a href="#_secrets_propertysource">Secrets PropertySource</a></li>
<li><a href="#_propertysource_reload"><code>PropertySource</code> Reload</a></li>
</ul>
</li>
<li><a href="#_ribbon_discovery_in_kubernetes">Ribbon Discovery in Kubernetes</a></li>
<li><a href="#_kubernetes_ecosystem_awareness">Kubernetes Ecosystem Awareness</a>
<ul class="sectlevel2">
<li><a href="#_kubernetes_profile_autoconfiguration">Kubernetes Profile Autoconfiguration</a></li>
<li><a href="#_istio_awareness">Istio Awareness</a></li>
</ul>
</li>
<li><a href="#_pod_health_indicator">Pod Health Indicator</a></li>
<li><a href="#_leader_election">Leader Election</a></li>
<li><a href="#_security_configurations_inside_kubernetes">Security Configurations Inside Kubernetes</a>
<ul class="sectlevel2">
<li><a href="#_namespace">Namespace</a></li>
<li><a href="#_service_account">Service Account</a></li>
</ul>
</li>
<li><a href="#_service_registry_implementation">Service Registry Implementation</a></li>
<li><a href="#_examples">Examples</a></li>
<li><a href="#_other_resources">Other Resources</a></li>
<li><a href="#_building">Building</a>
<ul class="sectlevel2">
<li><a href="#_basic_compile_and_test">Basic Compile and Test</a></li>
<li><a href="#_documentation">Documentation</a></li>
<li><a href="#_working_with_the_code">Working with the code</a></li>
</ul>
</li>
<li><a href="#_contributing">Contributing</a>
<ul class="sectlevel2">
<li><a href="#_sign_the_contributor_license_agreement">Sign the Contributor License Agreement</a></li>
<li><a href="#_code_of_conduct">Code of Conduct</a></li>
<li><a href="#_code_conventions_and_housekeeping">Code Conventions and Housekeeping</a></li>
<li><a href="#_checkstyle">Checkstyle</a></li>
<li><a href="#_ide_setup">IDE setup</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p>This reference guide covers how to use Spring Cloud Kubernetes.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_why_do_you_need_spring_cloud_kubernetes"><a class="link" href="#_why_do_you_need_spring_cloud_kubernetes">Why do you need Spring Cloud Kubernetes?</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Spring Cloud Kubernetes provide Spring Cloud common interface implementations that consume Kubernetes native services.
The main objective of the projects provided in this repository is to facilitate the integration of Spring Cloud and Spring Boot applications running inside Kubernetes.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_starters"><a class="link" href="#_starters">Starters</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Starters are convenient dependency descriptors you can include in your
application. Include a starter to get the dependencies and Spring Boot
auto-configuration for a feature set.</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Starter</th>
<th class="tableblock halign-left valign-top">Features</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><div class="content"><div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-kubernetes&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div></div></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#_discoveryclient_for_kubernetes">Discovery Client</a> implementation that
resolves service names to Kubernetes Services.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><div class="content"><div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-kubernetes-config&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div></div></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Load application properties from Kubernetes
<a href="#ConfigMap PropertySource">ConfigMaps</a> and <a href="#_secrets_propertysource">Secrets</a>.
<a href="#PropertySource Reload">Reload</a> application properties when a ConfigMap or
Secret changes.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><div class="content"><div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-kubernetes-ribbon&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div></div></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><a href="#Ribbon discovery in Kubernetes">Ribbon</a> client-side load balancer with
server list obtained from Kubernetes Endpoints.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><div class="content"><div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-kubernetes-all&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div></div></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">All Spring Cloud Kubernetes features.</p></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="sect1">
<h2 id="_discoveryclient_for_kubernetes"><a class="link" href="#_discoveryclient_for_kubernetes">DiscoveryClient for Kubernetes</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>This project provides an implementation of <a href="https://github.com/spring-cloud/spring-cloud-commons/blob/master/spring-cloud-commons/src/main/java/org/springframework/cloud/client/discovery/DiscoveryClient.java">Discovery Client</a>
for <a href="https://kubernetes.io">Kubernetes</a>.
This client lets you query Kubernetes endpoints (see <a href="https://kubernetes.io/docs/user-guide/services/">services</a>) by name.
A service is typically exposed by the Kubernetes API server as a collection of endpoints that represent <code>http</code> and <code>https</code> addresses and that a client can
access from a Spring Boot application running as a pod. This discovery feature is also used by the Spring Cloud Kubernetes Ribbon project
to fetch the list of the endpoints defined for an application to be load balanced.</p>
</div>
<div class="paragraph">
<p>This is something that you get for free by adding the following dependency inside your project:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-kubernetes&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>To enable loading of the <code>DiscoveryClient</code>, add <code>@EnableDiscoveryClient</code> to the according configuration or application class, as the following example shows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@SpringBootApplication
@EnableDiscoveryClient
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>Then you can inject the client in your code simply by autowiring it, as the following example shows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired
private DiscoveryClient discoveryClient;</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>If, for any reason, you need to disable the <code>DiscoveryClient</code>, you can set the following property in <code>application.properties</code>:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>spring.cloud.kubernetes.discovery.enabled=false</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>Some Spring Cloud components use the <code>DiscoveryClient</code> in order to obtain information about the local service instance. For
this to work, you need to align the Kubernetes service name with the <code>spring.application.name</code> property.</p>
</div>
<div class="paragraph">
<p>Spring Cloud Kubernetes can also watch the Kubernetes service catalog for changes and update the
<code>DiscoveryClient</code> implementation accordingly. In order to enable this functionality you need to add
<code>@EnableScheduling</code> on a configuration class in your application.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_kubernetes_native_service_discovery"><a class="link" href="#_kubernetes_native_service_discovery">Kubernetes native service discovery</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Kubernetes itself is capable of (server side) service discovery (see: <a href="https://kubernetes.io/docs/concepts/services-networking/service/#discovering-services" class="bare">https://kubernetes.io/docs/concepts/services-networking/service/#discovering-services</a>).
Using native kubernetes service discovery ensures compatibility with additional tooling, such as Istio (<a href="https://istio.io" class="bare">https://istio.io</a>), a service mesh that is capable of load balancing, ribbon, circuit breaker, failover, and much more.</p>
</div>
<div class="paragraph">
<p>The caller service then need only refer to names resolvable in a particular Kubernetes cluster. A simple implementation might use a spring <code>RestTemplate</code> that refers to a fully qualified domain name (FQDN), such as <code><a href="https://{service-name}.{namespace}.svc.{cluster}.local:{service-port}" class="bare">https://{service-name}.{namespace}.svc.{cluster}.local:{service-port}</a></code>.</p>
</div>
<div class="paragraph">
<p>Additionally, you can use Hystrix for:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Circuit breaker implementation on the caller side, by annotating the spring boot application class with <code>@EnableCircuitBreaker</code></p>
</li>
<li>
<p>Fallback functionality, by annotating the respective method with <code>@HystrixCommand(fallbackMethod=</code></p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_kubernetes_propertysource_implementations"><a class="link" href="#_kubernetes_propertysource_implementations">Kubernetes PropertySource implementations</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>The most common approach to configuring your Spring Boot application is to create an <code>application.properties</code> or <code>application.yaml</code> or
an <code>application-profile.properties</code> or <code>application-profile.yaml</code> file that contains key-value pairs that provide customization values to your
application or Spring Boot starters. You can override these properties by specifying system properties or environment
variables.</p>
</div>
<div class="sect2">
<h3 id="configmap-propertysource"><a class="link" href="#configmap-propertysource">Using a <code>ConfigMap</code> <code>PropertySource</code></a></h3>
<div class="paragraph">
<p>Kubernetes provides a resource named <a href="https://kubernetes.io/docs/user-guide/configmap/"><code>ConfigMap</code></a> to externalize the
parameters to pass to your application in the form of key-value pairs or embedded <code>application.properties</code> or <code>application.yaml</code> files.
The <a href="./spring-cloud-kubernetes-config">Spring Cloud Kubernetes Config</a> project makes Kubernetes <code>ConfigMap</code> instances available
during application bootstrapping and triggers hot reloading of beans or Spring context when changes are detected on
observed <code>ConfigMap</code> instances.</p>
</div>
<div class="paragraph">
<p>The default behavior is to create a <code>ConfigMapPropertySource</code> based on a Kubernetes <code>ConfigMap</code> that has a <code>metadata.name</code> value of either the name of
your Spring application (as defined by its <code>spring.application.name</code> property) or a custom name defined within the
<code>bootstrap.properties</code> file under the following key: <code>spring.cloud.kubernetes.config.name</code>.</p>
</div>
<div class="paragraph">
<p>However, more advanced configuration is possible where you can use multiple <code>ConfigMap</code> instances.
The <code>spring.cloud.kubernetes.config.sources</code> list makes this possible.
For example, you could define the following <code>ConfigMap</code> instances:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring:
application:
name: cloud-k8s-app
cloud:
kubernetes:
config:
name: default-name
namespace: default-namespace
sources:
# Spring Cloud Kubernetes looks up a ConfigMap named c1 in namespace default-namespace
- name: c1
# Spring Cloud Kubernetes looks up a ConfigMap named default-name in whatever namespace n2
- namespace: n2
# Spring Cloud Kubernetes looks up a ConfigMap named c3 in namespace n3
- namespace: n3
name: c3</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>In the preceding example, if <code>spring.cloud.kubernetes.config.namespace</code> had not been set,
the <code>ConfigMap</code> named <code>c1</code> would be looked up in the namespace that the application runs.</p>
</div>
<div class="paragraph">
<p>Any matching <code>ConfigMap</code> that is found is processed as follows:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Apply individual configuration properties.</p>
</li>
<li>
<p>Apply as <code>yaml</code> the content of any property named <code>application.yaml</code>.</p>
</li>
<li>
<p>Apply as a properties file the content of any property named <code>application.properties</code>.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>The single exception to the aforementioned flow is when the <code>ConfigMap</code> contains a <strong>single</strong> key that indicates
the file is a YAML or properties file. In that case, the name of the key does NOT have to be <code>application.yaml</code> or
<code>application.properties</code> (it can be anything) and the value of the property is treated correctly.
This features facilitates the use case where the <code>ConfigMap</code> was created by using something like the following:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>kubectl create configmap game-config --from-file=/path/to/app-config.yaml</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>Assume that we have a Spring Boot application named <code>demo</code> that uses the following properties to read its thread pool
configuration.</p>
</div>
<div class="ulist">
<ul>
<li>
<p><code>pool.size.core</code></p>
</li>
<li>
<p><code>pool.size.maximum</code></p>
</li>
</ul>
</div>
<div class="paragraph">
<p>This can be externalized to config map in <code>yaml</code> format as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo
data:
pool.size.core: 1
pool.size.max: 16</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>Individual properties work fine for most cases. However, sometimes, embedded <code>yaml</code> is more convenient. In this case, we
use a single property named <code>application.yaml</code> to embed our <code>yaml</code>, as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo
data:
application.yaml: |-
pool:
size:
core: 1
max:16</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>The following example also works:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo
data:
custom-name.yaml: |-
pool:
size:
core: 1
max:16</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>You can also configure Spring Boot applications differently depending on active profiles that are merged together
when the <code>ConfigMap</code> is read. You can provide different property values for different profiles by using an
<code>application.properties</code> or <code>application.yaml</code> property, specifying profile-specific values, each in their own document
(indicated by the <code>---</code> sequence), as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo
data:
application.yml: |-
greeting:
message: Say Hello to the World
farewell:
message: Say Goodbye
---
spring:
profiles: development
greeting:
message: Say Hello to the Developers
farewell:
message: Say Goodbye to the Developers
---
spring:
profiles: production
greeting:
message: Say Hello to the Ops</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>In the preceding case, the configuration loaded into your Spring Application with the <code>development</code> profile is as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml"> greeting:
message: Say Hello to the Developers
farewell:
message: Say Goodbye to the Developers</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>However, if the <code>production</code> profile is active, the configuration becomes:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml"> greeting:
message: Say Hello to the Ops
farewell:
message: Say Goodbye</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>If both profiles are active, the property that appears last within the <code>ConfigMap</code> overwrites any preceding values.</p>
</div>
<div class="paragraph">
<p>Another option is to create a different config map per profile and spring boot will automatically fetch it based
on active profiles</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo
data:
application.yml: |-
greeting:
message: Say Hello to the World
farewell:
message: Say Goodbye</code></pre>
</div>
</div>
</div>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo-development
data:
application.yml: |-
spring:
profiles: development
greeting:
message: Say Hello to the Developers
farewell:
message: Say Goodbye to the Developers</code></pre>
</div>
</div>
</div>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: ConfigMap
apiVersion: v1
metadata:
name: demo-production
data:
application.yml: |-
spring:
profiles: production
greeting:
message: Say Hello to the Ops
farewell:
message: Say Goodbye</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>To tell Spring Boot which <code>profile</code> should be enabled at bootstrap, you can pass <code>SPRING_PROFILES_ACTIVE</code> environment variable.
To do so, you can launch your Spring Boot application with an environment variable that you can define it in the PodSpec at the container specification.
Deployment resource file, as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment-name
labels:
app: deployment-name
spec:
replicas: 1
selector:
matchLabels:
app: deployment-name
template:
metadata:
labels:
app: deployment-name
spec:
containers:
- name: container-name
image: your-image
env:
- name: SPRING_PROFILES_ACTIVE
value: "development"</code></pre>
</div>
</div>
</div>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
You should check the security configuration section. To access config maps from inside a pod you need to have the correct
Kubernetes service accounts, roles and role bindings.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Another option for using <code>ConfigMap</code> instances is to mount them into the Pod by running the Spring Cloud Kubernetes application
and having Spring Cloud Kubernetes read them from the file system.
This behavior is controlled by the <code>spring.cloud.kubernetes.config.paths</code> property. You can use it in
addition to or instead of the mechanism described earlier.
You can specify multiple (exact) file paths in <code>spring.cloud.kubernetes.config.paths</code> by using the <code>,</code> delimiter.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
You have to provide the full exact path to each property file, because directories are not being recursively parsed.
</td>
</tr>
</table>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 1. Properties:</caption>
<colgroup>
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Name</th>
<th class="tableblock halign-left valign-top">Type</th>
<th class="tableblock halign-left valign-top">Default</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.config.enabled</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>true</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Enable ConfigMaps <code>PropertySource</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.config.name</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>String</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${spring.application.name}</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the name of <code>ConfigMap</code> to look up</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.config.namespace</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>String</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Client namespace</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the Kubernetes namespace where to lookup</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.config.paths</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>List</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>null</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the paths where <code>ConfigMap</code> instances are mounted</p></td>
</tr>
</tbody>
<tfoot>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.config.enableApi</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>true</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Enable or disable consuming <code>ConfigMap</code> instances through APIs</p></td>
</tr>
</tfoot>
</table>
</div>
<div class="sect2">
<h3 id="_secrets_propertysource"><a class="link" href="#_secrets_propertysource">Secrets PropertySource</a></h3>
<div class="paragraph">
<p>Kubernetes has the notion of <a href="https://kubernetes.io/docs/concepts/configuration/secret/">Secrets</a> for storing
sensitive data such as passwords, OAuth tokens, and so on. This project provides integration with <code>Secrets</code> to make secrets
accessible by Spring Boot applications. You can explicitly enable or disable This feature by setting the <code>spring.cloud.kubernetes.secrets.enabled</code> property.</p>
</div>
<div class="paragraph">
<p>When enabled, the <code>SecretsPropertySource</code> looks up Kubernetes for <code>Secrets</code> from the following sources:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Reading recursively from secrets mounts</p>
</li>
<li>
<p>Named after the application (as defined by <code>spring.application.name</code>)</p>
</li>
<li>
<p>Matching some labels</p>
</li>
</ol>
</div>
<div class="paragraph">
<p>Note that, by default, consuming Secrets through the API (points 2 and 3 above) <strong>is not enabled</strong> for security reasons.
Further, we recommend that containers share secrets through mounted volumes.
If you enable consuming Secrets through the API, we recommend that you limit access to Secrets by using an
[authorization policy, such as RBAC](<a href="https://kubernetes.io/docs/concepts/configuration/secret/#best-practices" class="bare">https://kubernetes.io/docs/concepts/configuration/secret/#best-practices</a>).</p>
</div>
<div class="paragraph">
<p>If the secrets are found, their data is made available to the application.</p>
</div>
<div class="paragraph">
<p>Assume that we have a spring boot application named <code>demo</code> that uses properties to read its database
configuration. We can create a Kubernetes secret by using the following command:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>oc create secret generic db-secret --from-literal=username=user --from-literal=password=p455w0rd</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>The preceding command would create the following secret (which you can see by using <code>oc get secrets db-secret -o yaml</code>):</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">apiVersion: v1
data:
password: cDQ1NXcwcmQ=
username: dXNlcg==
kind: Secret
metadata:
creationTimestamp: 2017-07-04T09:15:57Z
name: db-secret
namespace: default
resourceVersion: "357496"
selfLink: /api/v1/namespaces/default/secrets/db-secret
uid: 63c89263-6099-11e7-b3da-76d6186905a8
type: Opaque</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>Note that the data contains Base64-encoded versions of the literal provided by the <code>create</code> command.</p>
</div>
<div class="paragraph">
<p>Your application can then use this secret&#8201;&#8212;&#8201;for example, by exporting the secret&#8217;s value as environment variables:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">apiVersion: v1
kind: Deployment
metadata:
name: ${project.artifactId}
spec:
template:
spec:
containers:
- env:
- name: DB_USERNAME
valueFrom:
secretKeyRef:
name: db-secret
key: username
- name: DB_PASSWORD
valueFrom:
secretKeyRef:
name: db-secret
key: password</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>You can select the Secrets to consume in a number of ways:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>By listing the directories where secrets are mapped:</p>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-bash hljs" data-lang="bash">-Dspring.cloud.kubernetes.secrets.paths=/etc/secrets/db-secret,etc/secrets/postgresql</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>If you have all the secrets mapped to a common root, you can set them like:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-bash hljs" data-lang="bash">-Dspring.cloud.kubernetes.secrets.paths=/etc/secrets</code></pre>
</div>
</div>
</div>
</div>
</li>
<li>
<p>By setting a named secret:</p>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-bash hljs" data-lang="bash">-Dspring.cloud.kubernetes.secrets.name=db-secret</code></pre>
</div>
</div>
</div>
</div>
</li>
<li>
<p>By defining a list of labels:</p>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-bash hljs" data-lang="bash">-Dspring.cloud.kubernetes.secrets.labels.broker=activemq
-Dspring.cloud.kubernetes.secrets.labels.db=postgresql</code></pre>
</div>
</div>
</div>
</div>
</li>
</ol>
</div>
<div class="paragraph">
<p>As the case with <code>ConfigMap</code>, more advanced configuration is also possible where you can use multiple <code>Secret</code>
instances. The <code>spring.cloud.kubernetes.secrets.sources</code> list makes this possible.
For example, you could define the following <code>Secret</code> instances:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring:
application:
name: cloud-k8s-app
cloud:
kubernetes:
secrets:
name: default-name
namespace: default-namespace
sources:
# Spring Cloud Kubernetes looks up a Secret named s1 in namespace default-namespace
- name: s1
# Spring Cloud Kubernetes looks up a Secret named default-name in whatever namespace n2
- namespace: n2
# Spring Cloud Kubernetes looks up a Secret named s3 in namespace n3
- namespace: n3
name: s3</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>In the preceding example, if <code>spring.cloud.kubernetes.secrets.namespace</code> had not been set,
the <code>Secret</code> named <code>s1</code> would be looked up in the namespace that the application runs.</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 2. Properties:</caption>
<colgroup>
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Name</th>
<th class="tableblock halign-left valign-top">Type</th>
<th class="tableblock halign-left valign-top">Default</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.secrets.enabled</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>true</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Enable Secrets <code>PropertySource</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.secrets.name</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>String</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>${spring.application.name}</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the name of the secret to look up</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.secrets.namespace</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>String</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Client namespace</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the Kubernetes namespace where to look up</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.secrets.labels</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Map</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>null</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the labels used to lookup secrets</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.secrets.paths</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>List</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>null</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Sets the paths where secrets are mounted (example 1)</p></td>
</tr>
</tbody>
<tfoot>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.secrets.enableApi</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>false</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Enables or disables consuming secrets through APIs (examples 2 and 3)</p></td>
</tr>
</tfoot>
</table>
<div class="paragraph">
<p>Notes:
* The <code>spring.cloud.kubernetes.secrets.labels</code> property behaves as defined by
<a href="https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-Configuration-Binding#map-based-binding">Map-based binding</a>.
* The <code>spring.cloud.kubernetes.secrets.paths</code> property behaves as defined by
<a href="https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-Configuration-Binding#collection-based-binding">Collection-based binding</a>.
* Access to secrets through the API may be restricted for security reasons. The preferred way is to mount secrets to the Pod.</p>
</div>
<div class="paragraph">
<p>You can find an example of an application that uses secrets (though it has not been updated to use the new <code>spring-cloud-kubernetes</code> project) at
<a href="https://github.com/fabric8-quickstarts/spring-boot-camel-config">spring-boot-camel-config</a></p>
</div>
</div>
<div class="sect2">
<h3 id="_propertysource_reload"><a class="link" href="#_propertysource_reload"><code>PropertySource</code> Reload</a></h3>
<div class="paragraph">
<p>Some applications may need to detect changes on external property sources and update their internal status to reflect the new configuration.
The reload feature of Spring Cloud Kubernetes is able to trigger an application reload when a related <code>ConfigMap</code> or
<code>Secret</code> changes.</p>
</div>
<div class="paragraph">
<p>By default, this feature is disabled. You can enable it by using the <code>spring.cloud.kubernetes.reload.enabled=true</code> configuration property (for example, in the <code>application.properties</code> file).</p>
</div>
<div class="paragraph">
<p>The following levels of reload are supported (by setting the <code>spring.cloud.kubernetes.reload.strategy</code> property):
* <code>refresh</code> (default): Only configuration beans annotated with <code>@ConfigurationProperties</code> or <code>@RefreshScope</code> are reloaded.
This reload level leverages the refresh feature of Spring Cloud Context.
* <code>restart_context</code>: the whole Spring <code>ApplicationContext</code> is gracefully restarted. Beans are recreated with the new configuration.
* <code>shutdown</code>: the Spring <code>ApplicationContext</code> is shut down to activate a restart of the container.
When you use this level, make sure that the lifecycle of all non-daemon threads is bound to the <code>ApplicationContext</code>
and that a replication controller or replica set is configured to restart the pod.</p>
</div>
<div class="paragraph">
<p>Assuming that the reload feature is enabled with default settings (<code>refresh</code> mode), the following bean is refreshed when the config map changes:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre>@Configuration
@ConfigurationProperties(prefix = "bean")
public class MyConfig {
private String message = "a message that can be changed live";
// getter and setters
}</pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>To see that changes effectively happen, you can create another bean that prints the message periodically, as follows</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Component
public class MyBean {
@Autowired
private MyConfig config;
@Scheduled(fixedDelay = 5000)
public void hello() {
System.out.println("The message is: " + config.getMessage());
}
}</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>You can change the message printed by the application by using a <code>ConfigMap</code>, as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">apiVersion: v1
kind: ConfigMap
metadata:
name: reload-example
data:
application.properties: |-
bean.message=Hello World!</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>Any change to the property named <code>bean.message</code> in the <code>ConfigMap</code> associated with the pod is reflected in the
output. More generally speaking, changes associated to properties prefixed with the value defined by the <code>prefix</code>
field of the <code>@ConfigurationProperties</code> annotation are detected and reflected in the application.
<a href="#configmap-propertysource">Associating a <code>ConfigMap</code> with a pod</a> is explained earlier in this chapter.</p>
</div>
<div class="paragraph">
<p>The full example is available in <a href="https://github.com/fabric8io/spring-cloud-kubernetes/tree/master/spring-cloud-kubernetes-examples/kubernetes-reload-example"><code>spring-cloud-kubernetes-reload-example</code></a>.</p>
</div>
<div class="paragraph">
<p>The reload feature supports two operating modes:
* Event (default): Watches for changes in config maps or secrets by using the Kubernetes API (web socket).
Any event produces a re-check on the configuration and, in case of changes, a reload.
The <code>view</code> role on the service account is required in order to listen for config map changes. A higher level role (such as <code>edit</code>) is required for secrets
(by default, secrets are not monitored).
* Polling: Periodically re-creates the configuration from config maps and secrets to see if it has changed.
You can configure the polling period by using the <code>spring.cloud.kubernetes.reload.period</code> property and defaults to 15 seconds.
It requires the same role as the monitored property source.
This means, for example, that using polling on file-mounted secret sources does not require particular privileges.</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 3. Properties:</caption>
<colgroup>
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Name</th>
<th class="tableblock halign-left valign-top">Type</th>
<th class="tableblock halign-left valign-top">Default</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.reload.enabled</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>false</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Enables monitoring of property sources and configuration reload</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.reload.monitoring-config-maps</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>true</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Allow monitoring changes in config maps</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.reload.monitoring-secrets</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Boolean</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>false</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Allow monitoring changes in secrets</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.reload.strategy</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Enum</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>refresh</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">The strategy to use when firing a reload (<code>refresh</code>, <code>restart_context</code>, or <code>shutdown</code>)</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.reload.mode</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Enum</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>event</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Specifies how to listen for changes in property sources (<code>event</code> or <code>polling</code>)</p></td>
</tr>
</tbody>
<tfoot>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>spring.cloud.kubernetes.reload.period</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>Duration</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>15s</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">The period for verifying changes when using the <code>polling</code> strategy</p></td>
</tr>
</tfoot>
</table>
<div class="paragraph">
<p>Notes:
* You should not use properties under <code>spring.cloud.kubernetes.reload</code> in config maps or secrets. Changing such properties at runtime may lead to unexpected results.
* Deleting a property or the whole config map does not restore the original state of the beans when you use the <code>refresh</code> level.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_ribbon_discovery_in_kubernetes"><a class="link" href="#_ribbon_discovery_in_kubernetes">Ribbon Discovery in Kubernetes</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Spring Cloud client applications that call a microservice should be interested on relying on a client load-balancing
feature in order to automatically discover at which endpoint(s) it can reach a given service. This mechanism has been
implemented within the <a href="https://github.com/spring-cloud/spring-cloud-kubernetes/tree/master/spring-cloud-kubernetes-ribbon">spring-cloud-kubernetes-ribbon</a> project, where a
Kubernetes client populates a <a href="https://github.com/Netflix/ribbon">Ribbon</a> <code>ServerList</code> that contains information
about such endpoints.</p>
</div>
<div class="paragraph">
<p>The implementation is part of the following starter that you can use by adding its dependency to your pom file:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-kubernetes-ribbon&lt;/artifactId&gt;
&lt;version&gt;${latest.version}&lt;/version&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>When the list of the endpoints is populated, the Kubernetes client searches the registered endpoints that live in
the current namespace or project by matching the service name defined in the Ribbon Client annotation, as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@RibbonClient(name = "name-service")</code></pre>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>You can configure Ribbon&#8217;s behavior by providing properties in your <code>application.properties</code> (through your application&#8217;s
dedicated <code>ConfigMap</code>) by using the following format: <code>&lt;name of your service&gt;.ribbon.&lt;Ribbon configuration key&gt;</code>, where:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><code>&lt;name of your service&gt;</code> corresponds to the service name you access over Ribbon, as configured by using the
<code>@RibbonClient</code> annotation (such as <code>name-service</code> in the preceding example).</p>
</li>
<li>
<p><code>&lt;Ribbon configuration key&gt;</code> is one of the Ribbon configuration keys defined by
<a href="https://github.com/Netflix/ribbon/blob/master/ribbon-core/src/main/java/com/netflix/client/config/CommonClientConfigKey.java">Ribbon&#8217;s <code>CommonClientConfigKey</code> class</a>.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>Additionally, the <code>spring-cloud-kubernetes-ribbon</code> project defines two additional configuration keys to further
control how Ribbon interacts with Kubernetes. In particular, if an endpoint defines multiple ports, the default
behavior is to use the first one found. To select more specifically which port to use in a multi-port service, you can use
the <code>PortName</code> key. If you want to specify in which Kubernetes namespace the target service should be looked up, you can use
the <code>KubernetesNamespace</code> key, remembering in both instances to prefix these keys with your service name and
<code>ribbon</code> prefix, as specified earlier.</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 4. Spring Cloud Kubernetes Ribbon Configuration</caption>
<colgroup>
<col style="width: 33.3333%;">
<col style="width: 33.3333%;">
<col style="width: 33.3334%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Property Key</th>
<th class="tableblock halign-left valign-top">Type</th>
<th class="tableblock halign-left valign-top">Default Value</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">spring.cloud.kubernetes.ribbon.enabled</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">boolean</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">true</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">spring.cloud.kubernetes.ribbon.mode</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>KubernetesRibbonMode</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">POD</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">spring.cloud.kubernetes.ribbon.cluster-domain</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">cluster.local</p></td>
</tr>
</tbody>
</table>
<div class="ulist">
<ul>
<li>
<p><code>spring.cloud.kubernetes.ribbon.mode</code> supports <code>POD</code> and <code>SERVICE</code> modes.</p>
<div class="ulist">
<ul>
<li>
<p>The POD mode is to achieve load balancing by obtaining the Pod IP address of Kubernetes and using Ribbon.
POD mode uses the load balancing of the Ribbon Does not support Kubernetes load balancing, The traffic policy of <code>Istio</code> is not supported.</p>
</li>
<li>
<p>the <code>SERVICE</code> mode is directly based on the <code>service name</code> of the Ribbon. Get
The Kubernetes service is concatenated into <code>service-name.{namespace}.svc.{cluster.domain}:{port}</code> such as: <code>demo1.default.svc.cluster.local:8080</code>.
the <code>SERVICE</code> mode uses load balancing of the Kubernetes service to support Istio&#8217;s traffic policy.</p>
</li>
</ul>
</div>
</li>
<li>
<p><code>spring.cloud.kubernetes.ribbon.cluster-domain</code> Set the custom Kubernetes cluster domain suffix. The default value is: 'cluster.local'</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>The following examples use this module for ribbon discovery:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="./spring-cloud-kubernetes-examples/kubernetes-circuitbreaker-ribbon-example">Spring Cloud Circuitbreaker and Ribbon</a></p>
</li>
<li>
<p><a href="https://github.com/fabric8-quickstarts/spring-boot-ribbon">fabric8-quickstarts - Spring Boot - Ribbon</a></p>
</li>
<li>
<p><a href="https://github.com/fabric8io/kubeflix/tree/master/examples/loanbroker/bank">Kubeflix - LoanBroker - Bank</a></p>
</li>
</ul>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
You can disable the Ribbon discovery client by setting the <code>spring.cloud.kubernetes.ribbon.enabled=false</code> key within the application properties file.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_kubernetes_ecosystem_awareness"><a class="link" href="#_kubernetes_ecosystem_awareness">Kubernetes Ecosystem Awareness</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>All of the features described earlier in this guide work equally well, regardless of whether your application is running inside
Kubernetes. This is really helpful for development and troubleshooting.
From a development point of view, this lets you start your Spring Boot application and debug one
of the modules that is part of this project. You need not deploy it in Kubernetes,
as the code of the project relies on the
<a href="https://github.com/fabric8io/kubernetes-client">Fabric8 Kubernetes Java client</a>, which is a fluent DSL that can
communicate by using <code>http</code> protocol to the REST API of the Kubernetes Server.</p>
</div>
<div class="sect2">
<h3 id="_kubernetes_profile_autoconfiguration"><a class="link" href="#_kubernetes_profile_autoconfiguration">Kubernetes Profile Autoconfiguration</a></h3>
<div class="paragraph">
<p>When the application runs as a pod inside Kubernetes, a Spring profile named <code>kubernetes</code> automatically gets activated.
This lets you customize the configuration, to define beans that are applied when the Spring Boot application is deployed
within the Kubernetes platform (for example, different development and production configuration).</p>
</div>
</div>
<div class="sect2">
<h3 id="_istio_awareness"><a class="link" href="#_istio_awareness">Istio Awareness</a></h3>
<div class="paragraph">
<p>When you include the <code>spring-cloud-kubernetes-istio</code> module in the application classpath, a new profile is added to the application,
provided the application is running inside a Kubernetes Cluster with <a href="https://istio.io">Istio</a> installed. You can then use
spring <code>@Profile("istio")</code> annotations in your Beans and <code>@Configuration</code> classes.</p>
</div>
<div class="paragraph">
<p>The Istio awareness module uses <code>me.snowdrop:istio-client</code> to interact with Istio APIs, letting us discover traffic rules, circuit breakers, and so on,
making it easy for our Spring Boot applications to consume this data to dynamically configure themselves according to the environment.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_pod_health_indicator"><a class="link" href="#_pod_health_indicator">Pod Health Indicator</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Spring Boot uses <a href="https://github.com/spring-projects/spring-boot/blob/master/spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/HealthEndpoint.java"><code>HealthIndicator</code></a> to expose info about the health of an application.
That makes it really useful for exposing health-related information to the user and makes it a good fit for use as <a href="https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-probes/">readiness probes</a>.</p>
</div>
<div class="paragraph">
<p>The Kubernetes health indicator (which is part of the core module) exposes the following info:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Pod name, IP address, namespace, service account, node name, and its IP address</p>
</li>
<li>
<p>A flag that indicates whether the Spring Boot application is internal or external to Kubernetes</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_leader_election"><a class="link" href="#_leader_election">Leader Election</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>&lt;TBD&gt;</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_security_configurations_inside_kubernetes"><a class="link" href="#_security_configurations_inside_kubernetes">Security Configurations Inside Kubernetes</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_namespace"><a class="link" href="#_namespace">Namespace</a></h3>
<div class="paragraph">
<p>Most of the components provided in this project need to know the namespace. For Kubernetes (1.3+), the namespace is made available to the pod as part of the service account secret and is automatically detected by the client.
For earlier versions, it needs to be specified as an environment variable to the pod. A quick way to do this is as follows:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code> env:
- name: "KUBERNETES_NAMESPACE"
valueFrom:
fieldRef:
fieldPath: "metadata.namespace"</code></pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_service_account"><a class="link" href="#_service_account">Service Account</a></h3>
<div class="paragraph">
<p>For distributions of Kubernetes that support more fine-grained role-based access within the cluster, you need to make sure a pod that runs with <code>spring-cloud-kubernetes</code> has access to the Kubernetes API.
For any service accounts you assign to a deployment or pod, you need to make sure they have the correct roles.</p>
</div>
<div class="paragraph">
<p>Depending on the requirements, you&#8217;ll need <code>get</code>, <code>list</code> and <code>watch</code> permission on the following resources:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 5. Kubernetes Resource Permissions</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Dependency</th>
<th class="tableblock halign-left valign-top">Resources</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">spring-cloud-starter-kubernetes</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">pods, services, endpoints</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">spring-cloud-starter-kubernetes-config</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">configmaps, secrets</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">spring-cloud-starter-kubernetes-ribbon</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">pods, services, endpoints</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>For development purposes, you can add <code>cluster-reader</code> permissions to your <code>default</code> service account. On a production system you&#8217;ll likely want to provide more granular permissions.</p>
</div>
<div class="paragraph">
<p>The following Role and RoleBinding are an example for namespaced permissions for the <code>default</code> account:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
namespace: YOUR-NAME-SPACE
name: namespace-reader
rules:
- apiGroups: ["", "extensions", "apps"]
resources: ["configmaps", "pods", "services", "endpoints", "secrets"]
verbs: ["get", "list", "watch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: namespace-reader-binding
namespace: YOUR-NAME-SPACE
subjects:
- kind: ServiceAccount
name: default
apiGroup: ""
roleRef:
kind: Role
name: namespace-reader
apiGroup: ""</code></pre>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_service_registry_implementation"><a class="link" href="#_service_registry_implementation">Service Registry Implementation</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>In Kubernetes service registration is controlled by the platform, the application itself does not control
registration as it may do in other platforms. For this reason using <code>spring.cloud.service-registry.auto-registration.enabled</code>
or setting <code>@EnableDiscoveryClient(autoRegister=false)</code> will have no effect in Spring Cloud Kubernetes.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_examples"><a class="link" href="#_examples">Examples</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Spring Cloud Kubernetes tries to make it transparent for your applications to consume Kubernetes Native Services by
following the Spring Cloud interfaces.</p>
</div>
<div class="paragraph">
<p>In your applications, you need to add the <code>spring-cloud-kubernetes-discovery</code> dependency to your classpath and remove any other dependency that contains a <code>DiscoveryClient</code> implementation (that is, a Eureka discovery client).
The same applies for <code>PropertySourceLocator</code>, where you need to add to the classpath the <code>spring-cloud-kubernetes-config</code> and remove any other dependency that contains a <code>PropertySourceLocator</code> implementation (that is, a configuration server client).</p>
</div>
<div class="paragraph">
<p>The following projects highlight the usage of these dependencies and demonstrate how you can use these libraries from any Spring Boot application:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://github.com/spring-cloud/spring-cloud-kubernetes/tree/master/spring-cloud-kubernetes-examples">Spring Cloud Kubernetes Examples</a>: the ones located inside this repository.</p>
</li>
<li>
<p>Spring Cloud Kubernetes Full Example: Minions and Boss</p>
<div class="ulist">
<ul>
<li>
<p><a href="https://github.com/salaboy/spring-cloud-k8s-minion">Minion</a></p>
</li>
<li>
<p><a href="https://github.com/salaboy/spring-cloud-k8s-boss">Boss</a></p>
</li>
</ul>
</div>
</li>
<li>
<p>Spring Cloud Kubernetes Full Example: <a href="https://github.com/salaboy/s1p_docs">SpringOne Platform Tickets Service</a></p>
</li>
<li>
<p><a href="https://github.com/salaboy/s1p_gateway">Spring Cloud Gateway with Spring Cloud Kubernetes Discovery and Config</a></p>
</li>
<li>
<p><a href="https://github.com/salaboy/showcase-admin-tool">Spring Boot Admin with Spring Cloud Kubernetes Discovery and Config</a></p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_other_resources"><a class="link" href="#_other_resources">Other Resources</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>This section lists other resources, such as presentations (slides) and videos about Spring Cloud Kubernetes.</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://salaboy.com/2018/09/27/the-s1p-experience/">S1P Spring Cloud on PKS</a></p>
</li>
<li>
<p><a href="https://salaboy.com/2018/07/18/ljc-july-18-spring-cloud-docker-k8s/">Spring Cloud, Docker, Kubernetes &#8594; London Java Community July 2018</a></p>
</li>
</ul>
</div>
<div class="paragraph">
<p>Please feel free to submit other resources through pull requests to <a href="https://github.com/spring-cloud/spring-cloud-kubernetes">this repository</a>.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_building"><a class="link" href="#_building">Building</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_basic_compile_and_test"><a class="link" href="#_basic_compile_and_test">Basic Compile and Test</a></h3>
<div class="paragraph">
<p>To build the source you will need to install JDK 1.7.</p>
</div>
<div class="paragraph">
<p>Spring Cloud uses Maven for most build-related activities, and you
should be able to get off the ground quite quickly by cloning the
project you are interested in and typing</p>
</div>
<div class="listingblock">
<div class="content">
<pre>$ ./mvnw install</pre>
</div>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
You can also install Maven (&gt;=3.3.3) yourself and run the <code>mvn</code> command
in place of <code>./mvnw</code> in the examples below. If you do that you also
might need to add <code>-P spring</code> if your local Maven settings do not
contain repository declarations for spring pre-release artifacts.
</td>
</tr>
</table>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Be aware that you might need to increase the amount of memory
available to Maven by setting a <code>MAVEN_OPTS</code> environment variable with
a value like <code>-Xmx512m -XX:MaxPermSize=128m</code>. We try to cover this in
the <code>.mvn</code> configuration, so if you find you have to do it to make a
build succeed, please raise a ticket to get the settings added to
source control.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>For hints on how to build the project look in <code>.travis.yml</code> if there
is one. There should be a "script" and maybe "install" command. Also
look at the "services" section to see if any services need to be
running locally (e.g. mongo or rabbit). Ignore the git-related bits
that you might find in "before_install" since they&#8217;re related to setting git
credentials and you already have those.</p>
</div>
<div class="paragraph">
<p>The projects that require middleware generally include a
<code>docker-compose.yml</code>, so consider using
<a href="https://docs.docker.com/compose/">Docker Compose</a> to run the middeware servers
in Docker containers. See the README in the
<a href="https://github.com/spring-cloud-samples/scripts">scripts demo
repository</a> for specific instructions about the common cases of mongo,
rabbit and redis.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
If all else fails, build with the command from <code>.travis.yml</code> (usually
<code>./mvnw install</code>).
</td>
</tr>
</table>
</div>
</div>
<div class="sect2">
<h3 id="_documentation"><a class="link" href="#_documentation">Documentation</a></h3>
<div class="paragraph">
<p>The spring-cloud-build module has a "docs" profile, and if you switch
that on it will try to build asciidoc sources from
<code>src/main/asciidoc</code>. As part of that process it will look for a
<code>README.adoc</code> and process it by loading all the includes, but not
parsing or rendering it, just copying it to <code>${main.basedir}</code>
(defaults to <code>${basedir}</code>, 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.</p>
</div>
</div>
<div class="sect2">
<h3 id="_working_with_the_code"><a class="link" href="#_working_with_the_code">Working with the code</a></h3>
<div class="paragraph">
<p>If you don&#8217;t have an IDE preference we would recommend that you use
<a href="https://www.springsource.com/developer/sts">Spring Tools Suite</a> or
<a href="https://eclipse.org">Eclipse</a> when working with the code. We use the
<a href="https://eclipse.org/m2e/">m2eclipse</a> 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.</p>
</div>
<div class="sect3">
<h4 id="_importing_into_eclipse_with_m2eclipse"><a class="link" href="#_importing_into_eclipse_with_m2eclipse">Importing into eclipse with m2eclipse</a></h4>
<div class="paragraph">
<p>We recommend the <a href="https://eclipse.org/m2e/">m2eclipse</a> eclipse plugin when working with
eclipse. If you don&#8217;t already have m2eclipse installed it is available from the "eclipse
marketplace".</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Older versions of m2e do not support Maven 3.3, so once the
projects are imported into Eclipse you will also need to tell
m2eclipse to use the right profile for the projects. If you
see many different errors related to the POMs in the projects, check
that you have an up to date installation. If you can&#8217;t upgrade m2e,
add the "spring" profile to your <code>settings.xml</code>. Alternatively you can
copy the repository settings from the "spring" profile of the parent
pom into your <code>settings.xml</code>.
</td>
</tr>
</table>
</div>
</div>
<div class="sect3">
<h4 id="_importing_into_eclipse_without_m2eclipse"><a class="link" href="#_importing_into_eclipse_without_m2eclipse">Importing into eclipse without m2eclipse</a></h4>
<div class="paragraph">
<p>If you prefer not to use m2eclipse you can generate eclipse project metadata using the
following command:</p>
</div>
<div class="listingblock">
<div class="content">
<pre>$ ./mvnw eclipse:eclipse</pre>
</div>
</div>
<div class="paragraph">
<p>The generated eclipse projects can be imported by selecting <code>import existing projects</code>
from the <code>file</code> menu.</p>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_contributing"><a class="link" href="#_contributing">Contributing</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>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
to contribute even something trivial please do not hesitate, but
follow the guidelines below.</p>
</div>
<div class="sect2">
<h3 id="_sign_the_contributor_license_agreement"><a class="link" href="#_sign_the_contributor_license_agreement">Sign the Contributor License Agreement</a></h3>
<div class="paragraph">
<p>Before we accept a non-trivial patch or pull request we will need you to sign the
<a href="https://cla.pivotal.io/sign/spring">Contributor License Agreement</a>.
Signing the contributor&#8217;s agreement does not grant anyone commit rights to the main
repository, but it does mean that we can accept your contributions, and you will get an
author credit if we do. Active contributors might be asked to join the core team, and
given the ability to merge pull requests.</p>
</div>
</div>
<div class="sect2">
<h3 id="_code_of_conduct"><a class="link" href="#_code_of_conduct">Code of Conduct</a></h3>
<div class="paragraph">
<p>This project adheres to the Contributor Covenant <a href="https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc">code of
conduct</a>. By participating, you are expected to uphold this code. Please report
unacceptable behavior to <a href="mailto:spring-code-of-conduct@pivotal.io">spring-code-of-conduct@pivotal.io</a>.</p>
</div>
</div>
<div class="sect2">
<h3 id="_code_conventions_and_housekeeping"><a class="link" href="#_code_conventions_and_housekeeping">Code Conventions and Housekeeping</a></h3>
<div class="paragraph">
<p>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.</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Use the Spring Framework code format conventions. If you use Eclipse
you can import formatter settings using the
<code>eclipse-code-formatter.xml</code> file from the
<a href="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml">Spring
Cloud Build</a> project. If using IntelliJ, you can use the
<a href="https://plugins.jetbrains.com/plugin/6546">Eclipse Code Formatter
Plugin</a> to import the same file.</p>
</li>
<li>
<p>Make sure all new <code>.java</code> files to have a simple Javadoc class comment with at least an
<code>@author</code> tag identifying you, and preferably at least a paragraph on what the class is
for.</p>
</li>
<li>
<p>Add the ASF license header comment to all new <code>.java</code> files (copy from existing files
in the project)</p>
</li>
<li>
<p>Add yourself as an <code>@author</code> to the .java files that you modify substantially (more
than cosmetic changes).</p>
</li>
<li>
<p>Add some Javadocs and, if you change the namespace, some XSD doc elements.</p>
</li>
<li>
<p>A few unit tests would help a lot as well&#8201;&#8212;&#8201;someone has to do it.</p>
</li>
<li>
<p>If no-one else is using your branch, please rebase it against the current master (or
other target branch in the main project).</p>
</li>
<li>
<p>When writing a commit message please follow <a href="https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html">these conventions</a>,
if you are fixing an existing issue please add <code>Fixes gh-XXXX</code> at the end of the commit
message (where XXXX is the issue number).</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="_checkstyle"><a class="link" href="#_checkstyle">Checkstyle</a></h3>
<div class="paragraph">
<p>Spring Cloud Build comes with a set of checkstyle rules. You can find them in the <code>spring-cloud-build-tools</code> module. The most notable files under the module are:</p>
</div>
<div class="listingblock">
<div class="title">spring-cloud-build-tools/</div>
<div class="content">
<pre>└── src
   ├── checkstyle
   │   └── checkstyle-suppressions.xml <i class="conum" data-value="3"></i><b>(3)</b>
   └── main
   └── resources
   ├── checkstyle-header.txt <i class="conum" data-value="2"></i><b>(2)</b>
   └── checkstyle.xml <i class="conum" data-value="1"></i><b>(1)</b></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>Default Checkstyle rules</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>File header setup</td>
</tr>
<tr>
<td><i class="conum" data-value="3"></i><b>3</b></td>
<td>Default suppression rules</td>
</tr>
</table>
</div>
<div class="sect3">
<h4 id="_checkstyle_configuration"><a class="link" href="#_checkstyle_configuration">Checkstyle configuration</a></h4>
<div class="paragraph">
<p>Checkstyle rules are <strong>disabled by default</strong>. To add checkstyle to your project just define the following properties and plugins.</p>
</div>
<div class="listingblock">
<div class="title">pom.xml</div>
<div class="content">
<pre>&lt;properties&gt;
&lt;maven-checkstyle-plugin.failsOnError&gt;true&lt;/maven-checkstyle-plugin.failsOnError&gt; <i class="conum" data-value="1"></i><b>(1)</b>
&lt;maven-checkstyle-plugin.failsOnViolation&gt;true
&lt;/maven-checkstyle-plugin.failsOnViolation&gt; <i class="conum" data-value="2"></i><b>(2)</b>
&lt;maven-checkstyle-plugin.includeTestSourceDirectory&gt;true
&lt;/maven-checkstyle-plugin.includeTestSourceDirectory&gt; <i class="conum" data-value="3"></i><b>(3)</b>
&lt;/properties&gt;
&lt;build&gt;
&lt;plugins&gt;
&lt;plugin&gt; <i class="conum" data-value="4"></i><b>(4)</b>
&lt;groupId&gt;io.spring.javaformat&lt;/groupId&gt;
&lt;artifactId&gt;spring-javaformat-maven-plugin&lt;/artifactId&gt;
&lt;/plugin&gt;
&lt;plugin&gt; <i class="conum" data-value="5"></i><b>(5)</b>
&lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
&lt;artifactId&gt;maven-checkstyle-plugin&lt;/artifactId&gt;
&lt;/plugin&gt;
&lt;/plugins&gt;
&lt;reporting&gt;
&lt;plugins&gt;
&lt;plugin&gt; <i class="conum" data-value="5"></i><b>(5)</b>
&lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
&lt;artifactId&gt;maven-checkstyle-plugin&lt;/artifactId&gt;
&lt;/plugin&gt;
&lt;/plugins&gt;
&lt;/reporting&gt;
&lt;/build&gt;</pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>Fails the build upon Checkstyle errors</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Fails the build upon Checkstyle violations</td>
</tr>
<tr>
<td><i class="conum" data-value="3"></i><b>3</b></td>
<td>Checkstyle analyzes also the test sources</td>
</tr>
<tr>
<td><i class="conum" data-value="4"></i><b>4</b></td>
<td>Add the Spring Java Format plugin that will reformat your code to pass most of the Checkstyle formatting rules</td>
</tr>
<tr>
<td><i class="conum" data-value="5"></i><b>5</b></td>
<td>Add checkstyle plugin to your build and reporting phases</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If you need to suppress some rules (e.g. line length needs to be longer), then it&#8217;s enough for you to define a file under <code>${project.root}/src/checkstyle/checkstyle-suppressions.xml</code> with your suppressions. Example:</p>
</div>
<div class="listingblock">
<div class="title">projectRoot/src/checkstyle/checkstyle-suppresions.xml</div>
<div class="content">
<pre>&lt;?xml version="1.0"?&gt;
&lt;!DOCTYPE suppressions PUBLIC
"-//Puppy Crawl//DTD Suppressions 1.1//EN"
"https://www.puppycrawl.com/dtds/suppressions_1_1.dtd"&gt;
&lt;suppressions&gt;
&lt;suppress files=".*ConfigServerApplication\.java" checks="HideUtilityClassConstructor"/&gt;
&lt;suppress files=".*ConfigClientWatch\.java" checks="LineLengthCheck"/&gt;
&lt;/suppressions&gt;</pre>
</div>
</div>
<div class="paragraph">
<p>It&#8217;s advisable to copy the <code>${spring-cloud-build.rootFolder}/.editorconfig</code> and <code>${spring-cloud-build.rootFolder}/.springformat</code> to your project. That way, some default formatting rules will be applied. You can do so by running this script:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-bash hljs" data-lang="bash">$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/.editorconfig -o .editorconfig
$ touch .springformat</code></pre>
</div>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_ide_setup"><a class="link" href="#_ide_setup">IDE setup</a></h3>
<div class="sect3">
<h4 id="_intellij_idea"><a class="link" href="#_intellij_idea">Intellij IDEA</a></h4>
<div class="paragraph">
<p>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 <a href="https://github.com/spring-cloud/spring-cloud-build/tree/master/spring-cloud-build-tools">Spring Cloud Build</a> project.</p>
</div>
<div class="listingblock">
<div class="title">spring-cloud-build-tools/</div>
<div class="content">
<pre>└── src
   ├── checkstyle
   │   └── checkstyle-suppressions.xml <i class="conum" data-value="3"></i><b>(3)</b>
   └── main
   └── resources
   ├── checkstyle-header.txt <i class="conum" data-value="2"></i><b>(2)</b>
   ├── checkstyle.xml <i class="conum" data-value="1"></i><b>(1)</b>
   └── intellij
      ├── Intellij_Project_Defaults.xml <i class="conum" data-value="4"></i><b>(4)</b>
      └── Intellij_Spring_Boot_Java_Conventions.xml <i class="conum" data-value="5"></i><b>(5)</b></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>Default Checkstyle rules</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>File header setup</td>
</tr>
<tr>
<td><i class="conum" data-value="3"></i><b>3</b></td>
<td>Default suppression rules</td>
</tr>
<tr>
<td><i class="conum" data-value="4"></i><b>4</b></td>
<td>Project defaults for Intellij that apply most of Checkstyle rules</td>
</tr>
<tr>
<td><i class="conum" data-value="5"></i><b>5</b></td>
<td>Project style conventions for Intellij that apply most of Checkstyle rules</td>
</tr>
</table>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/images/intellij-code-style.png" alt="Code style">
</div>
<div class="title">Figure 1. Code style</div>
</div>
<div class="paragraph">
<p>Go to <code>File</code> &#8594; <code>Settings</code> &#8594; <code>Editor</code> &#8594; <code>Code style</code>. There click on the icon next to the <code>Scheme</code> section. There, click on the <code>Import Scheme</code> value and pick the <code>Intellij IDEA code style XML</code> option. Import the <code>spring-cloud-build-tools/src/main/resources/intellij/Intellij_Spring_Boot_Java_Conventions.xml</code> file.</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/images/intellij-inspections.png" alt="Code style">
</div>
<div class="title">Figure 2. Inspection profiles</div>
</div>
<div class="paragraph">
<p>Go to <code>File</code> &#8594; <code>Settings</code> &#8594; <code>Editor</code> &#8594; <code>Inspections</code>. There click on the icon next to the <code>Profile</code> section. There, click on the <code>Import Profile</code> and import the <code>spring-cloud-build-tools/src/main/resources/intellij/Intellij_Project_Defaults.xml</code> file.</p>
</div>
<div class="paragraph">
<div class="title">Checkstyle</div>
<p>To have Intellij work with Checkstyle, you have to install the <code>Checkstyle</code> plugin. It&#8217;s advisable to also install the <code>Assertions2Assertj</code> to automatically convert the JUnit assertions</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/images/intellij-checkstyle.png" alt="Checkstyle">
</div>
</div>
<div class="paragraph">
<p>Go to <code>File</code> &#8594; <code>Settings</code> &#8594; <code>Other settings</code> &#8594; <code>Checkstyle</code>. There click on the <code>+</code> icon in the <code>Configuration file</code> section. There, you&#8217;ll have to define where the checkstyle rules should be picked from. In the image above, we&#8217;ve picked the rules from the cloned Spring Cloud Build repository. However, you can point to the Spring Cloud Build&#8217;s GitHub repository (e.g. for the <code>checkstyle.xml</code> : <code><a href="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle.xml" class="bare">https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle.xml</a></code>). We need to provide the following variables:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><code>checkstyle.header.file</code> - please point it to the Spring Cloud Build&#8217;s, <code>spring-cloud-build-tools/src/main/resources/checkstyle/checkstyle-header.txt</code> file either in your cloned repo or via the <code><a href="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle-header.txt" class="bare">https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle-header.txt</a></code> URL.</p>
</li>
<li>
<p><code>checkstyle.suppressions.file</code> - default suppressions. Please point it to the Spring Cloud Build&#8217;s, <code>spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml</code> file either in your cloned repo or via the <code><a href="https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml" class="bare">https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml</a></code> URL.</p>
</li>
<li>
<p><code>checkstyle.additional.suppressions.file</code> - this variable corresponds to suppressions in your local project. E.g. you&#8217;re working on <code>spring-cloud-contract</code>. Then point to the <code>project-root/src/checkstyle/checkstyle-suppressions.xml</code> folder. Example for <code>spring-cloud-contract</code> would be: <code>/home/username/spring-cloud-contract/src/checkstyle/checkstyle-suppressions.xml</code>.</p>
</li>
</ul>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Remember to set the <code>Scan Scope</code> to <code>All sources</code> since we apply checkstyle rules for production and test sources.
</td>
</tr>
</table>
</div>
</div>
</div>
</div>
</div>
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