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Adjusting configuration and adding documentation

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This commit is contained in:
Nicola Ferraro
2016-10-11 16:02:18 +02:00
committed by Ioannis Canellos
parent 41bb31fd4c
commit 3d766effa6
12 changed files with 246 additions and 53 deletions
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29
example/src/main/java/io/app/MyBean.java
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@@ -1,29 +0,0 @@
package io.app;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
/**
*
*/
@Component
@ConfigurationProperties(prefix = "bean")
public class MyBean {
private String message;
@Scheduled(fixedDelay = 5000)
public void hello() {
System.out.println("The message is: " + message);
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}

9
example/src/main/resources/application.properties
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@@ -1,9 +0,0 @@
spring.application.name=example
#spring.cloud.kubernetes.reload.strategy=refresh
#spring.cloud.kubernetes.reload.mode=polling
#spring.cloud.kubernetes.reload.period=2000
#spring.cloud.kubernetes.reload.monitoring-config-maps=false
#spring.cloud.kubernetes.reload.monitoring-secrets=true
#spring.cloud.kubernetes.reload.enabled=true

4
pom.xml
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@@ -80,6 +80,7 @@
<kubernetes-client.version>1.4.14</kubernetes-client.version>
<mockwebserver.version>0.0.4</mockwebserver.version>
<lombok.version>1.16.8</lombok.version>
<hibernate-validator.version>5.2.4.Final</hibernate-validator.version>
<servlet-api.version>2.5</servlet-api.version>
<spock-spring.version>1.0-groovy-2.3</spock-spring.version>
<spring-boot.version>1.4.1.RELEASE</spring-boot.version>
@@ -90,6 +91,7 @@
<!-- Maven Plugin Versions -->
<maven-compiler-plugin.version>3.5</maven-compiler-plugin.version>
<maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
<fabric8.maven.plugin.version>3.1.69</fabric8.maven.plugin.version>
<gmavenplus-plugin.version>1.2</gmavenplus-plugin.version>
<sundrio-plugin.vesion>0.3.4</sundrio-plugin.vesion>
</properties>
@@ -106,7 +108,7 @@
<module>spring-cloud-starter-kubernetes-netflix</module>
<module>spring-cloud-starter-kubernetes-zipkin</module>
<module>spring-cloud-starter-kubernetes-all</module>
<module>example</module>
<module>spring-cloud-kubernetes-examples</module>
</modules>
<dependencyManagement>

77
readme.md
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@@ -11,6 +11,7 @@
- [PropertySource](#kubernetes-propertysource)
- [ConfigMap PropertySource](#configmap-propertysource)
- [Secrets PropertySource](#secrets-propertysource)
- [PropertySource Reload](#propertysource-reload)
- [Pod Health Indicator](#pod-health-indicator)
- [Transparency](#transparency) *(its transparent wether the code runs in or outside of Kubernetes)*
- [Kubernetes Profile Autoconfiguration](#kubernetes-profile-autoconfiguration)
@@ -199,13 +200,13 @@ You can select the Secrets to consume in a number of ways:
#### PropertySource Reload
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 its related ConfigMap or Secret change.
The reload feature of Spring Cloud Kubernetes is able to trigger an application reload when a related ConfigMap or Secret change.
This feature is disabled by default and can be enabled using the configuration property `spring.cloud.kubernetes.reload.enabled=true`
(eg. in the *application.properties* file).
The following levels of reload are supported (property `spring.cloud.kubernetes.reload.strategy`):
- **refresh (default)**: only spring beans annotated with `@ConfigurationProperties` or `@RefreshScope` are reloaded.
- **refresh (default)**: only configuration beans annotated with `@ConfigurationProperties` or `@RefreshScope` are reloaded.
This reload level leverages the refresh feature of Spring Cloud Context.
- **restart_context**: the whole Spring _ApplicationContext_ is gracefully restarted. Beans are recreated with the new configuration.
- **shutdown**: the Spring _ApplicationContext_ is shut down to activate a restart of the container.
@@ -214,8 +215,78 @@ This reload level leverages the refresh feature of Spring Cloud Context.
Example:
Assuming that the reload feature is enabled with default settings, the following bean will be refreshed
Assuming that the reload feature is enabled with default settings (*refresh* mode), the following bean will be refreshed when the config map changes:
```java
@Configuration
@ConfigurationProperties(prefix = "bean")
public class MyConfig {
private String message = "a message that can be changed live";
// getter and setters
}
```
A way to see that changes effectively happen is creating another bean that prints the message periodically.
```java
@Component
public class MyBean {
@Autowired
private MyConfig config;
@Scheduled(fixedDelay = 5000)
public void hello() {
System.out.println("The message is: " + config.getMessage());
}
}
```
The message printed by the application can be changed using a config map like the following one:
```yml
apiVersion: v1
kind: ConfigMap
metadata:
name: reload-example
data:
application.properties: |-
bean.message=Hello World!
```
Any change to the property named `bean.message` in the Config Map associated to the pod will be reflected in the output of the program
(more details [here](#configmap-propertysource) about how to associate a Config Map to a pod).
The full example is available in [spring-cloud-kubernetes-reload-example](spring-cloud-kubernetes-examples/spring-cloud-kubernetes-reload-example).
The reload feature supports two operating modes:
- **event (default)**: watches for changes in config maps or secrets using the Kubernetes API (web socket).
Any event will produce a re-check on the configuration and a reload in case of changes.
The `view` role on the service account is required in order to listen for config map changes. A higher level role (eg. `edit`) is required for secrets
(secrets are not monitored by default).
- **polling**: re-creates the configuration periodically from config maps and secrets to see if it has changed.
The polling period can be configured using the property `spring.cloud.kubernetes.reload.period` 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.
Properties:
| Name | Type | Default | Description
| --- | --- | --- | ---
| spring.cloud.kubernetes.reload.enabled | Boolean | false | Enables monitoring of property sources and configuration reload
| spring.cloud.kubernetes.reload.monitoring-config-maps | Boolean | true | Allow monitoring changes in config maps
| spring.cloud.kubernetes.reload.monitoring-secrets | Boolean | false | Allow monitoring changes in secrets
| spring.cloud.kubernetes.reload.strategy | Enum | refresh | The strategy to use when firing a reload (*refresh*, *restart_context*, *shutdown*)
| spring.cloud.kubernetes.reload.mode | Enum | event | Specifies how to listen for changes in property sources (*event*, *polling*)
| spring.cloud.kubernetes.reload.period | Long | 15000 | The period in milliseconds for verifying changes when using the *polling* strategy
Notes:
- Properties under *spring.cloud.kubernetes.reload.** should not be used 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 using the *refresh* level.
### Pod Health Indicator

8
spring-cloud-kubernetes-examples/kubernetes-reload-example/config-map.yml Normal file
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@@ -0,0 +1,8 @@
apiVersion: v1
kind: ConfigMap
metadata:
name: reload-example
data:
application.properties: |-
bean.message=Hello World!
another.property=value

43
example/pom.xml → spring-cloud-kubernetes-examples/kubernetes-reload-example/pom.xml
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@@ -3,14 +3,28 @@
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>spring-cloud-kubernetes-project</artifactId>
<artifactId>spring-cloud-kubernetes-examples</artifactId>
<groupId>io.fabric8</groupId>
<version>0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>example</artifactId>
<artifactId>kubernetes-reload-example</artifactId>
<name>Fabric8 :: Spring Cloud Kubernetes :: Examples :: Reload</name>
<description>Example demostrating how to use the configuration reload feature.</description>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<type>pom</type>
<scope>import</scope>
<version>${spring-boot.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
@@ -19,20 +33,29 @@
<version>${project.version}</version>
</dependency>
<!--<dependency>-->
<!--<groupId>org.springframework.cloud</groupId>-->
<!--<artifactId>spring-cloud-config-client</artifactId>-->
<!--</dependency>-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<version>1.4.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.2.4.Final</version>
<version>${hibernate-validator.version}</version>
</dependency>
</dependencies>
@@ -42,7 +65,7 @@
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>3.1.69</version>
<version>${fabric8.maven.plugin.version}</version>
<executions>
<execution>
<goals>

54
spring-cloud-kubernetes-examples/kubernetes-reload-example/readme.md Normal file
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@@ -0,0 +1,54 @@
## Kubernetes Reload Example
This example demonstrate how to use the reload feature to change the configuration of a spring-boot application at runtime.
The application consists of a timed bean that periodically prints a message to the console.
The message can be changed using a config map.
### Running the example
When using Openshift, you must assign the `view` role to the *default* service account in the current project:
```
oc policy add-role-to-user view --serviceaccount=default
```
You can deploy the application using the fabric8 maven plugin:
```
mvn clean install fabric8:deploy
```
### Changing the configuration
Create a yaml file with the following contents:
```yml
apiVersion: v1
kind: ConfigMap
metadata:
name: reload-example
data:
application.properties: |-
bean.message=Hello World!
another.property=value
```
A sample config map is provided with this example in the *config-map.yml* file.
To deploy the config map, just run the following command:
```
oc create -f config-map.yml
```
As soon as the config map is deployed, the output of the application changes accordingly.
The config map can be now edited with the following command:
```
oc edit configmap reload-example
```
Changes are applied immediately when using the *event* reload mode.
The name of the config map (*"reload-example"*) matches the name of the application as declared in the *application.properties* file.

4
example/src/main/java/io/app/App.java → spring-cloud-kubernetes-examples/kubernetes-reload-example/src/main/java/io/fabric8/spring/cloud/kubernetes/examples/App.java
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@@ -1,12 +1,14 @@
package io.app;
package io.fabric8.spring.cloud.kubernetes.examples;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
/**
*
*/
@SpringBootApplication
@EnableScheduling
public class App {
public static void main(String[] args) {

19
spring-cloud-kubernetes-examples/kubernetes-reload-example/src/main/java/io/fabric8/spring/cloud/kubernetes/examples/MyBean.java Normal file
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@@ -0,0 +1,19 @@
package io.fabric8.spring.cloud.kubernetes.examples;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
@Component
public class MyBean {
@Autowired
private MyConfig config;
@Scheduled(fixedDelay = 5000)
public void hello() {
System.out.println("The message is: " + config.getMessage());
}
}

20
spring-cloud-kubernetes-examples/kubernetes-reload-example/src/main/java/io/fabric8/spring/cloud/kubernetes/examples/MyConfig.java Normal file
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@@ -0,0 +1,20 @@
package io.fabric8.spring.cloud.kubernetes.examples;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConfigurationProperties(prefix = "bean")
public class MyConfig {
private String message = "a message that can be changed live";
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}

9
spring-cloud-kubernetes-examples/kubernetes-reload-example/src/main/resources/application.properties Normal file
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@@ -0,0 +1,9 @@
spring.application.name=reload-example
spring.cloud.kubernetes.reload.enabled=true
#spring.cloud.kubernetes.reload.strategy=restart_context
#spring.cloud.kubernetes.reload.mode=polling
#spring.cloud.kubernetes.reload.period=5000
#spring.cloud.kubernetes.reload.monitoring-config-maps=false
#spring.cloud.kubernetes.reload.monitoring-secrets=true

23
spring-cloud-kubernetes-examples/pom.xml Normal file
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@@ -0,0 +1,23 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>spring-cloud-kubernetes-project</artifactId>
<groupId>io.fabric8</groupId>
<version>0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>spring-cloud-kubernetes-examples</artifactId>
<packaging>pom</packaging>
<name>Fabric8 :: Spring Cloud Kubernetes :: Examples</name>
<description>Examples showing how to use features of Spring Cloud Kubernetes.</description>
<modules>
<module>kubernetes-reload-example</module>
</modules>
</project>