spring-cloud-kubernetes与k8s的configmap

ClarissaElvis 发布于1年前

本文是《spring-cloud-kubernetes实战系列》的第六篇,主要内容是在kubernetes上部署一个java web应用,该应用使用了spring-cloud-kubernetes框架,可以使用kubernetes的configmap;

系列文章列表

  1. 《spring-cloud-kubernetes官方demo运行实战》
  2. 《你好spring-cloud-kubernetes》
  3. 《spring-cloud-kubernetes背后的三个关键知识点》
  4. 《spring-cloud-kubernetes的服务发现和轮询实战(含熔断)》
  5. 《spring-cloud-kubernetes与SpringCloud Gateway》
  6. 《spring-cloud-kubernetes与k8s的configmap》
  7. 《spring-cloud-kubernetes自动同步k8s的configmap更新》

关于SpringCloud Config

如果您开发过SpringCloud应用,相信您对SpringCloud Config不会陌生,在微服务环境中,业务应用可以从config server获取所需的配置信息,如下图所示:

spring-cloud-kubernetes与k8s的configmap

关于kubernetes的configmap

这是kubernetes提供的基本服务之一,创建一个configmap资源,对应着一份配置文件,可以将该资源通过数据卷的形式映射到Pod上,这样Pod就能用上这个配置文件了,如下图:

spring-cloud-kubernetes与k8s的configmap

spring-cloud-kubernetes带来的礼物

spring-cloud-starter-kubernetes-config是spring-cloud-starter-kubernetes框架下的一个库,作用是将kubernetes的configmap与SpringCloud Config结合起来,通过spring-cloud-starter-kubernetes-config,我们的应用就像在通过SpringCloud Config取得配置信息,只不过这里的配置信息来自kubernetes的configmap,而不是SpringCloud Config server,如下图所示:

spring-cloud-kubernetes与k8s的configmap

理论上的准备工作已经差不多了,接下来通过实战来展示spring-cloud-starter-kubernetes-config的神奇之处;

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,本章的应用在springcloudk8sconfigdemo文件夹下,如下图所示:

spring-cloud-kubernetes与k8s的configmap

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
  7. springboot:2.1.6.RELEASE

准备完毕,可以开始实战啦!

编码

  1. 通过maven创建名为springcloudk8sconfigdemo的springboot工程,pom.xml内容如下,要注意的是新增了依赖spring-cloud-starter-kubernetes-config,这是本次实战的重点:
<?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>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.bolingcavalry</groupId>
    <artifactId>springcloudk8sconfigdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springcloudk8sconfigdemo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-boot.version>2.1.6.RELEASE</spring-boot.version>
        <maven-checkstyle-plugin.failsOnError>false</maven-checkstyle-plugin.failsOnError>
        <maven-checkstyle-plugin.failsOnViolation>false</maven-checkstyle-plugin.failsOnViolation>
        <maven-checkstyle-plugin.includeTestSourceDirectory>false</maven-checkstyle-plugin.includeTestSourceDirectory>
        <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>
        <springcloud.kubernetes.version>1.0.1.RELEASE</springcloud.kubernetes.version>
        <spring-cloud.version>Greenwich.SR2</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-kubernetes-config</artifactId>
            <version>${springcloud.kubernetes.version}</version>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <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>
    </profiles>
</project>
  1. 项目的src\main\resources路径下不要创建application.yml文件,只创建名为bootstrap.yml的文件,内容如下:
spring:
  application:
    name: springcloudk8sconfigdemo
  cloud:
    kubernetes:
      config:
        sources:
          - name: ${spring.application.name}
            namespace: default

可见新增了配置项spring.cloud.kubernetes.config.source.name和spring.cloud.kubernetes.config.source.namespace,用于配置信息来源于kubernetes的哪个namespace下的哪个configmap;

  1. 增加一个配置类DummyConfig.java,注解ConfigurationProperties的prefix="greeting"表示该类用到的配置项都是名为"greeting"的配置项的子内容 :
package com.bolingcavalry.springcloudk8sconfigdemo;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConfigurationProperties(prefix = "greeting")
public class DummyConfig {

    private String message = "This is a dummy message";

    public String getMessage() {
        return this.message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}
  1. 启动类Springcloudk8sconfigdemoApplication.java,简单起见,将用于验证配置项是否生效的web接口也写在了这里面,即hello方法 :
package com.bolingcavalry.springcloudk8sconfigdemo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.text.SimpleDateFormat;
import java.util.Date;

@SpringBootApplication
@RestController
@EnableConfigurationProperties(DummyConfig.class)
public class Springcloudk8sconfigdemoApplication {

    @Autowired
    private DummyConfig dummyConfig;

    @GetMapping("/hello")
    public String hello() {
        return dummyConfig.getMessage()
                + " ["
                + new SimpleDateFormat().format(new Date())
                + "]";
    }

    public static void main(String[] args) {
        SpringApplication.run(Springcloudk8sconfigdemoApplication.class, args);
    }
}

以上就是实战工程的所有代码了,仅仅只是引入了spring-cloud-kubernetes-config的依赖,以及在启动配置文件中指定了configmap的信息,即完成了获取配置文件的所有操作,至于代码中用到配置文件的地方,和使用SpringCloud Config并无差别。

解决权限问题

我这里的是minikube,在部署了应用之后,默认的serviceaccount是没有权限访问K8S的API Server资源的,执行以下命令可以提升权限:

kubectl create clusterrolebinding permissive-binding \
  --clusterrole=cluster-admin \
  --user=admin \
  --user=kubelet \
  --group=system:serviceaccounts

注意:以上办法只能用于开发和测试环境,不要用在生产环境,生产环境应参考Kubernetes的RBAC授权相关设置来处理,步骤如下:

  1. 创建role:
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: default
  name: pod-reader
rules:
  - apiGroups: [""]
    resources: ["pods","configmaps"]
    verbs: ["get", "watch", "list"]
  1. 创建ServiceAccount:
apiVersion: v1
kind: ServiceAccount
metadata:
  name: config-reader
  namespace: default
  1. 绑定Role和ServiceAccount:
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: pod-reader
  namespace: default
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: pod-reader
subjects:
  - kind: ServiceAccount
    name: config-reader
    namespace: default
  1. 在deployment中指定上面的ServiceAccount;

验证

接下来我们在kubernetes环境创建configmap,再将springcloudk8sconfigdemo在kubernetes部署和启动,通过springcloudk8sconfigdemo提供的http接口验证应用是否已经从configmap中取得指定的配置;

  1. 在kubernetes环境新建名为springcloudk8sconfigdemo.yml的文件,内容如下:
kind: ConfigMap
apiVersion: v1
metadata:
  name: springcloudk8sconfigdemo
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
  1. 在springcloudk8sconfigdemo.yml文件所在目录执行以下命令,即可在kubernetes创建名为的configmap的资源:
kubectl apply -f springcloudk8sconfigdemo.yml
  1. 在springcloudk8sconfigdemo项目的pom.xml文件所在目录,执行以下命令,即可编译构建部署全部完成:
mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes

操作成功后的控制台信息如下:

[INFO] Installing /usr/local/work/k8s/springcloudk8sconfigdemo/target/classes/META-INF/fabric8/kubernetes.json to /root/.m2/repository/com/bolingcavalry/springcloudk8sconfigdemo/0.0.1-SNAPSHOT/springcloudk8sconfigdemo-0.0.1-SNAPSHOT-kubernetes.json
[INFO] 
[INFO] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ springcloudk8sconfigdemo <<<
[INFO] 
[INFO] 
[INFO] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ springcloudk8sconfigdemo ---
[INFO] F8: Using Kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/k8s/springcloudk8sconfigdemo/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-springcloudk8sconfigdemo.json
[INFO] Using namespace: default
[INFO] Updating Deployment from kubernetes.yml
[INFO] Updated Deployment: target/fabric8/applyJson/default/deployment-springcloudk8sconfigdemo.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:  13.538 s
[INFO] Finished at: 2019-07-14T17:06:25+08:00
[INFO] ------------------------------------------------------------------------
  1. 如果您的环境也是minikube,可以执行以下命令查看服务地址:
minikube service springcloudk8sconfigdemo --url

得到服务地址是:http://192.168.121.133:31646

  1. 浏览器访问地址:http://192.168.121.133:31646/hello ,得到响应如下图,可见已经从configmap取得了配置文件,并且加载成功:

    spring-cloud-kubernetes与k8s的configmap

    修改profile

    前面的实战没有指定springboot工程的profile,接下来指定profile为development,看能否加载到配置文件中指定的配置,如下图红框所示:

    spring-cloud-kubernetes与k8s的configmap
  2. 修改项目的src\main\resources路径下的bootstrap.yml文件,增加配置项spring.profiles.active,修改后的完整内容如下:
spring:
  application:
    name: springcloudk8sconfigdemo
  profiles:
    active: development
  cloud:
    kubernetes:
      config:
        sources:
          - name: ${spring.application.name}
            namespace: default
  1. 在springcloudk8sconfigdemo项目的pom.xml文件所在目录,执行以下命令,即可编译构建部署全部完成:
mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes
  1. 如果您的环境也是minikube,可以执行以下命令查看服务地址:
minikube service springcloudk8sconfigdemo --url

得到服务地址是:http://192.168.121.133:30659

  1. 浏览器访问地址:http://192.168.121.133:30659/hello ,得到响应如下图,可见已经从configmap取得了指定profile的配置文件,并且加载成功:

    spring-cloud-kubernetes与k8s的configmap

    至此,spring-cloud-kubernetes与k8s的configmap的实战就完成了,我们可以发现借助spring-cloud-kubernetes-config的神奇能力,曾经使用SpringCloud Config来配置的应用几乎不用修改代码,仅仅调整了配置和依赖,就能顺利迁移到kubernetes之上,直接使用原生的配置服务,并且SpringCloud Config Server也可以不用在kubernetes上部署了,再次感受到SpringCloud设计的前瞻性。

一点遗憾

虽然我们的应用已经成功从configmap取得配置信息,但遗憾的是,configmap的配置信息被修改后,这些修改是无法实时同步到我们的应用的,只能重启应用来重现获取配置,为了解决这个问题,请参考本系列的下一篇 《spring-cloud-kubernetes自动同步k8s的configmap更新》

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spring-cloud-kubernetes与k8s的configmap

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