环境
- kubernetes 1.20.2
- Spring Boot 2.5.0-M1
目标
构建一个 Spring Boot Actuator 镜像，并在 Kubernetes 环境上运行，查看与普通环境上的区别。
Spring Boot Actuator
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.5.0-M1</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<groupId>jiangbo.spring.demo</groupId>
<artifactId>spring-demo</artifactId>
<version>actuator</version>
<name>spring-boot-demo</name>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<id>build-info</id>
<goals>
<goal>build-info</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</pluginRepository>
</pluginRepositories>
</project>
SpringDemoApplication
package jiangbo.spring.docker;
import java.net.InetAddress;
import java.net.UnknownHostException;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.info.BuildProperties;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@RestController
public class SpringDemoApplication {
private final BuildProperties buildProperties;
public SpringDemoApplication(BuildProperties buildProperties) {
this.buildProperties = buildProperties;
}
private static String hostname;
public static void main(String[] args) throws UnknownHostException {
hostname = InetAddress.getLocalHost().getHostName();
SpringApplication.run(SpringDemoApplication.class, args);
}
@GetMapping("/hostname")
public String hello() {
return hostname + " " + buildProperties.getVersion();
}
}
application.yaml
management:
endpoint:
shutdown:
enabled: true
endpoints:
web:
exposure:
include: "*"
Dockerfile
FROM openjdk:8-jre-alpine as builder
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
RUN java -Djarmode=layertools -jar application.jar extract
FROM openjdk:8-jre-alpine
COPY --from=builder dependencies/ ./
COPY --from=builder snapshot-dependencies/ ./
COPY --from=builder spring-boot-loader/ ./
COPY --from=builder application/ ./
ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher"]
构建镜像
打包
PS D:workspacestsspring-demo> mvn clean package
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< jiangbo.spring.demo:spring-demo >-------------------
[INFO] Building spring-boot-demo actuator
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-clean-plugin:3.1.0:clean (default-clean) @ spring-demo ---
[INFO] Deleting D:workspacestsspring-demo arget
[INFO]
[INFO] --- spring-boot-maven-plugin:2.5.0-M1:build-info (build-info) @ spring-demo ---
[INFO]
[INFO] --- maven-resources-plugin:3.2.0:resources (default-resources) @ spring-demo ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Using 'UTF-8' encoding to copy filtered properties files.
[INFO] Copying 1 resource
[INFO] Copying 0 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ spring-demo ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to D:workspacestsspring-demo argetclasses
[INFO]
[INFO] --- maven-resources-plugin:3.2.0:testResources (default-testResources) @ spring-demo ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Using 'UTF-8' encoding to copy filtered properties files.
[INFO] skip non existing resourceDirectory D:workspacestsspring-demosrc est
esources
[INFO]
[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ spring-demo ---
[INFO] Changes detected - recompiling the module!
[INFO]
[INFO] --- maven-surefire-plugin:2.22.2:test (default-test) @ spring-demo ---
[INFO]
[INFO] --- maven-jar-plugin:3.2.0:jar (default-jar) @ spring-demo ---
[INFO] Building jar: D:workspacestsspring-demo argetspring-demo-actuator.jar
[INFO]
[INFO] --- spring-boot-maven-plugin:2.5.0-M1:repackage (repackage) @ spring-demo ---
[INFO] Replacing main artifact with repackaged archive
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7.433 s
[INFO] Finished at: 2021-01-25T21:47:17+08:00
[INFO] ------------------------------------------------------------------------
构建镜像
PS D:workspacestsspring-demo> docker build -t jiangbo920827/spring-demo:actuator .
Sending build context to Docker daemon 19.2MB
Step 1/10 : FROM openjdk:8-jre-alpine as builder
---> f7a292bbb70c
Step 2/10 : ARG JAR_FILE=target/*.jar
---> Using cache
---> 061b93704007
Step 3/10 : COPY ${JAR_FILE} application.jar
---> 20e5f2fa61e3
Step 4/10 : RUN java -Djarmode=layertools -jar application.jar extract
---> Running in e5028a5d2546
Removing intermediate container e5028a5d2546
---> 6cfa89d4fe04
Step 5/10 : FROM openjdk:8-jre-alpine
---> f7a292bbb70c
Step 6/10 : COPY --from=builder dependencies/ ./
---> Using cache
---> 94c069dd1619
Step 7/10 : COPY --from=builder snapshot-dependencies/ ./
---> Using cache
---> 1aba6579c120
Step 8/10 : COPY --from=builder spring-boot-loader/ ./
---> Using cache
---> 1f67b70f1647
Step 9/10 : COPY --from=builder application/ ./
---> 6143bdef4fd0
Step 10/10 : ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher"]
---> Running in 3bee9efaf294
Removing intermediate container 3bee9efaf294
---> 27b1db723cf2
Successfully built 27b1db723cf2
Successfully tagged jiangbo920827/spring-demo:actuator
SECURITY WARNING: You are building a Docker image from Windows against a non-Windows Docker host.
All files and directories added to build context will have '-rwxr-xr-x' permissions.
It is recommended to double check and reset permissions for sensitive files and directories.
推送到远程仓库
PS D:workspacestsspring-demo> docker push jiangbo920827/spring-demo:actuator
The push refers to repository [docker.io/jiangbo920827/spring-demo]
da6a673c5c81: Pushed
b06e2e5a3a34: Mounted from jiangbo920827/spring-docker
7d97b13df67a: Mounted from jiangbo920827/spring-docker
edd61588d126: Mounted from jiangbo920827/spring-docker
9b9b7f3d56a0: Mounted from jiangbo920827/spring-docker
f1b5933fe4b5: Mounted from library/openjdk
actuator: digest: sha256:fef2dd74c274e783e4cf2f270da15cadbc0766c8a0d24dad31dd0258e2eb4722 size: 1576
创建 Pod
pod.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-demo
spec:
containers:
- name: pod-demo
image: jiangbo920827/spring-demo:actuator
ports:
- containerPort: 8080
创建
[root@master pod]# kubectl apply -f pod.yaml
pod/pod-demo created
查看
[root@master pod]# kubectl get -f pod.yaml -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-demo 1/1 Running 0 5m12s 10.244.1.16 node1 <none> <none>
比较
同时在本地和 Kubernetes 环境上访问 http://localhost:8080/actuator/health 。
本地访问
{
"status": "UP"
}
Kubernetes 访问
URL 根据 Pod 的实际 IP 填写。
{
"status": "UP",
"groups": [
"liveness",
"readiness"
]
}
总结
介绍了创建 Spring Boot Actuator 的镜像，并以 Pod 的方式启动。
比较了本地和 Kubernetes 的环境暴露健康端点的不通。
附录
Spring Boot 判断 Kubernetes 环境
Spring Boot 判断 Kubernetes 环境的源码如下：
/**
* Kubernetes platform.
*/
KUBERNETES {
private static final String KUBERNETES_SERVICE_HOST = "KUBERNETES_SERVICE_HOST";
private static final String KUBERNETES_SERVICE_PORT = "KUBERNETES_SERVICE_PORT";
private static final String SERVICE_HOST_SUFFIX = "_SERVICE_HOST";
private static final String SERVICE_PORT_SUFFIX = "_SERVICE_PORT";
@Override
public boolean isDetected(Environment environment) {
if (environment instanceof ConfigurableEnvironment) {
return isAutoDetected((ConfigurableEnvironment) environment);
}
return false;
}
private boolean isAutoDetected(ConfigurableEnvironment environment) {
PropertySource<?> environmentPropertySource = environment.getPropertySources()
.get(StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME);
if (environmentPropertySource != null) {
if (environmentPropertySource.containsProperty(KUBERNETES_SERVICE_HOST)
&& environmentPropertySource.containsProperty(KUBERNETES_SERVICE_PORT)) {
return true;
}
if (environmentPropertySource instanceof EnumerablePropertySource) {
return isAutoDetected((EnumerablePropertySource<?>) environmentPropertySource);
}
}
return false;
}
private boolean isAutoDetected(EnumerablePropertySource<?> environmentPropertySource) {
for (String propertyName : environmentPropertySource.getPropertyNames()) {
if (propertyName.endsWith(SERVICE_HOST_SUFFIX)) {
String serviceName = propertyName.substring(0,
propertyName.length() - SERVICE_HOST_SUFFIX.length());
if (environmentPropertySource.getProperty(serviceName + SERVICE_PORT_SUFFIX) != null) {
return true;
}
}
}
return false;
}
};
判断 Kubernetes 环境
if (CloudPlatform.getActive(environment) == CloudPlatform.KUBERNETES) {
return ConditionOutcome.match(message.because("running on Kubernetes"));
}