你好spring-cloud-kubernetes开源项目

文章作者:欣宸,前阿里工程师

关于spring-cloud-kubernetes

spring-cloud-kubernetes是springcloud官方推出的开源项目,用于将Spring Cloud和Spring Boot应用运行在kubernetes环境,并且提供了通用的接口来调用kubernetes服务,GitHub上官方地址是:https://github.com/spring-cloud/spring-cloud-kubernetes

该项目的提交者之一,就是SpringCloud的作者之一Spencer Gibb:

通过官方demo来了解spring-cloud-kubernetes

spring-cloud-kubernetes项目也提供了丰富的官方demo来帮助开发者了解和学习spring-cloud-kubernetes,您可以参考《spring-cloud-kubernetes官方demo运行实战》快速体验官方demo;

实战spring-cloud-kubernetes

今天实战的内容是开发一个简单的java应用,然后将其部署在kubernetes环境(minikube 1.1.1),该应用通过spring-cloud-kubernetes调用当前kubernetes的服务;

环境信息

本次实战的环境和版本信息如下:

  1. 操作系统:CentOS Linux release 7.6.1810
  2. minikube:1.1.1
  3. Java:1.8.0_191
  4. Maven:3.6.0
  5. fabric8-maven-plugin插件:3.5.37
  6. spring-cloud-kubernetes:1.0.1.RELEASE

上面的linux、minikube、java、maven,请确保已准备好,linux环境下minikube的安装和启动请参考《Linux安装minikube指南 》

准备工作已经OK,开始编码吧。

源码下载

如果您不打算写代码,也可以从GitHub上下载本次实战的源码,地址和链接信息如下表所示:

名称 链接 备注
项目主页 https://github.com/zq2599/blog_demos 该项目在GitHub上的主页
git仓库地址(https) https://github.com/zq2599/blog_demos.git 该项目源码的仓库地址,https协议
git仓库地址(ssh) git@github.com:zq2599/blog_demos.git 该项目源码的仓库地址,ssh协议

这个git项目中有多个文件夹,本章源码在springcloudk8sdiscovery这个文件夹下,如下图红框所示: 在这里插入图片描述

开发应用

1.基于maven创建一个springboot应用,名为springcloudk8sdiscovery;

2.该应用完整的pom.xml内容如下:

<?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">

    <modelVersion>4.0.0</modelVersion>

    <parent>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-parent</artifactId>

        <version>2.1.1.RELEASE</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

    <groupId>com.bolingcavalry</groupId>

    <artifactId>springcloudk8sdiscovery</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>springcloudk8sdiscovery</name>

    <description>Demo project for Spring Boot</description>



    <properties>

        <java.version>1.8</java.version>

        <spring-boot.version>2.1.1.RELEASE</spring-boot.version>

        <maven-compiler-plugin.version>3.5</maven-compiler-plugin.version>

        <maven-deploy-plugin.version>2.8.2</maven-deploy-plugin.version>

        <maven-failsafe-plugin.version>2.18.1</maven-failsafe-plugin.version>

        <maven-surefire-plugin.version>2.21.0</maven-surefire-plugin.version>

        <fabric8.maven.plugin.version>3.5.37</fabric8.maven.plugin.version>

    </properties>



    <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>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-kubernetes-core</artifactId>

            <version>1.0.1.RELEASE</version>

        </dependency>



        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-kubernetes-discovery</artifactId>

            <version>1.0.1.RELEASE</version>

        </dependency>



        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-commons</artifactId>

            <version>2.1.1.RELEASE</version>

        </dependency>



        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter</artifactId>

            <version>2.1.1.RELEASE</version>

        </dependency>



        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

            <version>2.1.1.RELEASE</version>

        </dependency>



        <!--

            We need that(actuator) so that it can be used in readiness probes.

            Readiness checks are needed by arquillian, so that it

            knows when to run the actual test.

        -->

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

            <version>2.1.1.RELEASE</version>

        </dependency>



        <dependency>

            <groupId>com.alibaba</groupId>

            <artifactId>fastjson</artifactId>

            <version>1.2.28</version>

        </dependency>

    </dependencies>





    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

                <version>${spring-boot.version}</version>

                <executions>

                    <execution>

                        <goals>

                            <goal>repackage</goal>

                        </goals>

                    </execution>

                </executions>

            </plugin>



            <plugin>

                <!--skip deploy -->

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-deploy-plugin</artifactId>

                <version>${maven-deploy-plugin.version}</version>

                <configuration>

                    <skip>true</skip>

                </configuration>

            </plugin>

            <plugin>

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-surefire-plugin</artifactId>

                <version>${maven-surefire-plugin.version}</version>

                <configuration>

                    <skipTests>true</skipTests>

                    <!-- Workaround for https://issues.apache.org/jira/browse/SUREFIRE-1588 -->

                    <useSystemClassLoader>false</useSystemClassLoader>

                </configuration>

            </plugin>

            <plugin>

                <groupId>io.fabric8</groupId>

                <artifactId>fabric8-maven-plugin</artifactId>

                <version>${fabric8.maven.plugin.version}</version>

                <executions>

                    <execution>

                        <id>fmp</id>

                        <goals>

                            <goal>resource</goal>

                        </goals>

                    </execution>

                </executions>

            </plugin>

        </plugins>

    </build>



    <profiles>

        <profile>

            <id>kubernetes</id>

            <build>

                <plugins>

                    <plugin>

                        <groupId>io.fabric8</groupId>

                        <artifactId>fabric8-maven-plugin</artifactId>

                        <version>${fabric8.maven.plugin.version}</version>

                        <executions>

                            <execution>

                                <id>fmp</id>

                                <goals>

                                    <goal>resource</goal>

                                    <goal>build</goal>

                                </goals>

                            </execution>

                        </executions>

                        <configuration>

                            <enricher>

                                <config>

                                    <fmp-service>

                                        <type>NodePort</type>

                                    </fmp-service>

                                </config>

                            </enricher>

                        </configuration>

                    </plugin>

                </plugins>

            </build>

        </profile>

        <profile>

            <id>release</id>

            <build>

                <plugins>

                    <plugin>

                        <groupId>io.fabric8</groupId>

                        <artifactId>fabric8-maven-plugin</artifactId>

                        <version>${fabric8.maven.plugin.version}</version>

                        <executions>

                            <execution>

                                <id>fmp</id>

                                <goals>

                                    <goal>resource</goal>

                                    <goal>helm</goal>

                                </goals>

                            </execution>

                        </executions>

                    </plugin>

                </plugins>

            </build>

        </profile>



        <profile>

            <id>integration</id>

            <build>

                <plugins>

                    <plugin>

                        <groupId>io.fabric8</groupId>

                        <artifactId>fabric8-maven-plugin</artifactId>

                        <version>${fabric8.maven.plugin.version}</version>

                        <executions>

                            <execution>

                                <id>fmp</id>

                                <goals>

                                    <goal>resource</goal>

                                    <goal>build</goal>

                                </goals>

                            </execution>

                        </executions>

                    </plugin>

                    <plugin>

                        <groupId>org.apache.maven.plugins</groupId>

                        <artifactId>maven-failsafe-plugin</artifactId>

                        <version>${maven-failsafe-plugin.version}</version>

                        <executions>

                            <execution>

                                <id>run-integration-tests</id>

                                <phase>integration-test</phase>

                                <goals>

                                    <goal>integration-test</goal>

                                    <goal>verify</goal>

                                </goals>

                            </execution>

                        </executions>

                        <configuration>

                            <skipTests>false</skipTests>

                            <skipITs>false</skipITs>

                        </configuration>

                    </plugin>

                </plugins>

            </build>

        </profile>

    </profiles>

</project>

上述pom.xml文件有几处需要关注: a. 直接依赖了spring-cloud-kubernetes的以下两个库,后面才能使用spring-cloud-kubernetes的服务:

org.springframework.cloud:spring-cloud-kubernetes-core:1.0.1.RELEASE

org.springframework.cloud:spring-cloud-kubernetes-discovery:1.0.1.RELEASE

b. 使用插件fabric8-maven-plugin来构建镜像并部署到minikube环境:

<plugin>

  <groupId>io.fabric8</groupId>

  <artifactId>fabric8-maven-plugin</artifactId>

  <version>${fabric8.maven.plugin.version}</version>

  <executions>

    <execution>

      <id>fmp</id>

      <goals>

        <goal>resource</goal>

      </goals>

    </execution>

  </executions>

</plugin>

c. 为fabric8-maven-plugin插件准备了三个profile,本次实战主要用到kubernetes这个:

<profile> 

  <id>kubernetes</id>  

  <build> 

    <plugins> 

      <plugin> 

        <groupId>io.fabric8</groupId>  

        <artifactId>fabric8-maven-plugin</artifactId>  

        <version>${fabric8.maven.plugin.version}</version>  

        <executions> 

          <execution> 

            <id>fmp</id>  

            <goals>

              <goal>resource</goal>  

              <goal>build</goal> 

            </goals> 

          </execution> 

        </executions>  

        <configuration> 

          <enricher> 

            <config> 

              <fmp-service>

                <!--部署到kubernetes后,会创建一个类型为NodePort的service--> 

                <type>NodePort</type> 

              </fmp-service> 

            </config> 

          </enricher> 

        </configuration> 

      </plugin> 

    </plugins> 

  </build> 

</profile>

以上就是pom.xml的内容了,主要是添加spring-cloud-kubernetes的依赖,以及使用fabric8来构建和部署;

3.在application.properties文件中设置应用名称:

spring.application.name=springcloudk8sdiscovery

4.创建应用启动类Springcloudk8sdiscoveryApplication,可见这是个很普通的springboot启动类:

package com.bolingcavalry.springcloudk8sdiscovery;



import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.client.discovery.EnableDiscoveryClient;



@SpringBootApplication

@EnableDiscoveryClient

public class Springcloudk8sdiscoveryApplication {



    public static void main(String[] args) {

        SpringApplication.run(Springcloudk8sdiscoveryApplication.class, args);

    }

}

5.创建controller类,对外提供http服务,部署完成后通过这些http服务来验证功能:

@RestController

public class DiscoveryController {



    @Autowired

    private DiscoveryClient discoveryClient;



    /**

     * 探针检查响应类

     * @return

     */

    @RequestMapping("/health")

    public String health() {

        return "health";

    }



    /**

     * 返回远程调用的结果

     * @return

     */

    @RequestMapping("/getservicedetail")

    public String getservicedetail(

            @RequestParam(value = "servicename", defaultValue = "") String servicename) {

        return "Service [" + servicename + "]'s instance list : " + JSON.toJSONString(discoveryClient.getInstances(servicename));

    }



    /**

     * 返回发现的所有服务

     * @return

     */

    @RequestMapping("/services")

    public String services() {

        return this.discoveryClient.getServices().toString()

                + ", "

                + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());

    }

}

上述代码有几点需要注意: a. health方法用于响应kubernetes的探针检查; b. getservicedetail方法接收名为servicename的参数,然后去服务列表中检查对应的服务对象并返回; c. services方法返回的是所有服务的名称;

以上就是所有代码了,功能是通过autowire得到DiscoveryClient实例,再调用该实例的API取得服务信息。

接下来我们将应用构建并部署到minikube环境;

编译构建

1.请确保当前电脑上java、maven、minikube都是正常的;

2.在pom.xml文件所在目录执行以下命令,即可编译构建部署一次性完成:

mvn clean package fabric8:deploy -Pkubernetes

构建成功后,控制台输出信息如下:

...

[INFO] 

[INFO] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ springcloudk8sdiscovery <<<

[INFO] 

[INFO] 

[INFO] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ springcloudk8sdiscovery ---

[INFO] F8: Using Kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/demo/springcloudk8sdiscovery/target/classes/META-INF/fabric8/kubernetes.yml 

[INFO] Using namespace: default

[INFO] Updating a Service from kubernetes.yml

[INFO] Updated Service: target/fabric8/applyJson/default/service-springcloudk8sdiscovery.json

[INFO] Using namespace: default

[INFO] Updating Deployment from kubernetes.yml

[INFO] Updated Deployment: target/fabric8/applyJson/default/deployment-springcloudk8sdiscovery.json

[INFO] F8: HINT: Use the command `kubectl get pods -w` to watch your pods start up

[INFO] ------------------------------------------------------------------------

[INFO] BUILD SUCCESS

[INFO] ------------------------------------------------------------------------

[INFO] Total time:  11.207 s

[INFO] Finished at: 2019-06-09T18:50:09+08:00

[INFO] ————————————————————————

3.用kubectl命令查看部署和服务,都处于正常状态:

[root@minikube springcloudk8sdiscovery]# kubectl get deployments

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE

springcloudk8sdiscovery   1/1     1            1           75m

[root@minikube springcloudk8sdiscovery]# kubectl get svc

NAME                      TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE

kubernetes                ClusterIP   10.96.0.1       <none>        443/TCP          33h

springcloudk8sdiscovery   NodePort    10.102.167.79   <none>        8080:31583/TCP   75m

4.执行命令minikube service springcloudk8sdiscovery –url,得到的是可以从外部访问的服务地址:http://192.168.121.133:31583 ,其中192.168.121.133是宿主机IP地址;

5.在浏览器上访问地址http://192.168.121.133:31583/services ,如下图,返回的”所有服务”其实是kubernetes中的所有service: 在这里插入图片描述

6.为了验证当前namespace下的所有服务都能被发现,我们再创建个服务实施,执行以下命令,会创建名为my-tomcat的部署和服务:

kubectl run my-tomcat --image=tomcat:7.0.94-jre7-alpine --replicas=2 --port=8080 \

&& kubectl expose deployment my-tomcat --port=8080 --target-port=8080 --external-ip=192.168.50.7 --type=LoadBalancer

7.由于下载镜像需要一定时间,所以需要稍作等待;

  1. 再去访问地址http://192.168.121.133:31583/services ,如下图,my-tomcat赫然在列: 在这里插入图片描述

8.访问地址http://192.168.121.133:31583/getservicedetail?servicename=my-tomcat ,会得到名为my-tomcat的服务信息,该信息格式化后的内容如下所示:

[

    {

        "host": "172.17.0.4",

        "instanceId": "91201db9-8aa6-11e9-a5b5-000c29fd2001",

        "metadata": {

            "run": "my-tomcat"

        },

        "port": 8080,

        "scheme": "http://",

        "secure": false,

        "serviceId": "my-tomcat",

        "uri": "http://172.17.0.4:8080"

    },

    {

        "host": "172.17.0.5",

        "instanceId": "91223cda-8aa6-11e9-a5b5-000c29fd2001",

        "metadata": {

            "$ref": "$[0].metadata"

        },

        "port": 8080,

        "scheme": "http://",

        "secure": false,

        "serviceId": "my-tomcat",

        "uri": "http://172.17.0.5:8080"

    }

]

可见spring-cloud-kubernetes的DiscoveryClient服务将kubernetes中的”service”资源与SpringCloud中的服务对应起来了,有了这个DiscoveryClient,我们在kubernetes环境就不需要eureka来做注册发现了,而是直接使用kubernetes的服务机制,此时不得不感慨SpringCloud的对DiscoveryClient的设计是如此的精妙。

至此,spring-cloud-kubernetes的初体验就结束了,通过简单的编码我们的程序在kubernetes环境可以取得service资源的信息,随着学习的深入,我们会用到更多的spring-cloud-kubernetes能力,感谢spring-cloud-kubernetes的设计者,让我们的SpringCloud应用畅游在在kubernetes世界。

疑惑待解

您可能会有些疑惑:上面的代码都是和SpringCloud相关的,和spring-cloud-kubernetes没什么关系呀,为什么程序运行起来后就能取得kubernetes环境中的服务信息呢? 此问题如果不弄清楚,后面的学习很难展开,因为我们都不知道自己的代码与kubernetes环境有什么关系,和kubernetes有没有交互?

本文只是初步了解spring-cloud-kubernetes,并不适合深入讨论,这些问题还是留待下一章吧。

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