本文是《spring-cloud-kubernetes实战系列》的第四篇，主要内容是在kubernetes上部署两个应用：Web-Service和Account-Service，通过spring-cloud-kubernetes提供的注册发现能力，实现Web-Service调用Account-Service提供的http服务；
系列文章列表
- 《spring-cloud-kubernetes官方demo运行实战》
- 《你好spring-cloud-kubernetes》
- 《spring-cloud-kubernetes背后的三个关键知识点》
- 《spring-cloud-kubernetes的服务发现和轮询实战(含熔断)》
- 《spring-cloud-kubernetes与SpringCloud Gateway》
- 《spring-cloud-kubernetes与k8s的configmap》
全文概览
本文由以下段落组成：
- 环境信息
- 常见的SpringCloud注册发现服务一览
- 分析kubernetes上如何实现服务注册发现
- 本章实战源码下载链接
- 实战开发Account-Service服务(服务提供方)
- 实战开发Web-Service服务(服务消费方)
- 扩容验证ribbon轮询能力
- 验证熔断能力
环境信息
本次实战的环境和版本信息如下：
- 操作系统：CentOS Linux release 7.6.1810
- minikube：1.1.1
- Java：1.8.0_191
- Maven：3.6.0
- fabric8-maven-plugin插件：3.5.37
- 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 》。
常见的SpringCloud注册发现服务一览
SpringCloud环境最重要的功能是注册发现服务，因此将SpringCloud应用迁移到kubernetes环境时，开发者最关心的问题是在kubernetes上如何将自身服务暴露出去，以及如何调用其他微服务。
先看看普通SpringCloud环境下的注册发现，下图来自spring官方博客，地址是：https://spring.io/blog/2015/0...，
由上图可见，应用Account-Service将自己注册到Eureka，这样Web-Service用"account-service"就能在Eureka找到Account-Service服务的地址，然后顺利发送RestFul请求到Account-Service，用上其提供的服务。
分析kubernetes上如何实现服务注册发现
如果将上面的Web-Service和Account-Service两个应用迁移到kubernetes上之后，注册发现机制变成了啥样呢？
第一种：沿用上图的方式，将Eureka也部署在kubernetes上，这样的架构和不用kubernetes时没有啥区别；
第二种，就是今天要实战的内容，使用spring-cloud-kubernetes框架，该框架可以调用kubernetes的原生能力来为现有SpringCloud应用提供服务，架构如下图所示：
上图表明，Web-Service应用在调用Account-Service应用的服务时，会用okhttp向API Server请求服务列表，API Server收到请求后会去etcd取数据返回给Web-Service应用，这样Web-Service就有了Account-Service的信息，可以向Account-Service的多个Pod轮询发起请求；
上图有个细节请注意：WebService应用并不是直接将请求发送给Account-Service在kubernetes创建的service，而是直接发送到具体的Pod上了，之所以具有这个能力，是因为spring-cloud-kubernetes框架通过service拿到了Account-Service对应的所有Pod信息（endpoint），此逻辑可以参考源码KubernetesServerList.java，如下所示：
public List<Server> getUpdatedListOfServers() {
//用namespace和serviceId做条件，得到该服务对应的所有节点(endpoints)信息
Endpoints endpoints = this.namespace != null
? this.client.endpoints().inNamespace(this.namespace)
.withName(this.serviceId).get()
: this.client.endpoints().withName(this.serviceId).get();
List<Server> result = new ArrayList<Server>();
if (endpoints != null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Found [" + endpoints.getSubsets().size()
+ "] endpoints in namespace [" + this.namespace + "] for name ["
+ this.serviceId + "] and portName [" + this.portName + "]");
}
//遍历所有的endpoint，取出IP地址和端口，构建成Server实例，放入result集合中
for (EndpointSubset subset : endpoints.getSubsets()) {
if (subset.getPorts().size() == 1) {
EndpointPort port = subset.getPorts().get(FIRST);
for (EndpointAddress address : subset.getAddresses()) {
result.add(new Server(address.getIp(), port.getPort()));
}
}
else {
for (EndpointPort port : subset.getPorts()) {
if (Utils.isNullOrEmpty(this.portName)
|| this.portName.endsWith(port.getName())) {
for (EndpointAddress address : subset.getAddresses()) {
result.add(new Server(address.getIp(), port.getPort()));
}
}
}
}
}
}
else {
LOG.warn("Did not find any endpoints in ribbon in namespace ["
+ this.namespace + "] for name [" + this.serviceId
+ "] and portName [" + this.portName + "]");
}
return result;
}理论分析已经完成，接下来就开始实战吧
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/blo... | 该项目在GitHub上的主页 |
| git仓库地址(https) | https://github.com/zq2599/blo... | 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Account-Service源码在spring-cloud-k8s-account-service文件夹下，Web-Service源码在spring-cloud-k8s-web-service文件夹下，如下图红框所示：
下面是详细的编码过程；
开发和部署Account-Service服务
Account-Service服务是个很普通的springboot应用，和spring-cloud-kubernetes没有任何关系：
- 通过maven创建一个springboot应用，artifactId是<font color="blue">account-service</font>，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>account-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>account-service</name>
<description>Demo project for Spring Cloud service provider run in kubernetes</description>
<properties>
<java.version>1.8</java.version>
<spring-boot.version>2.1.1.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.version>2.1.1.RELEASE</springcloud.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<type>pom</type>
<scope>import</scope>
<version>${spring-boot.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<version>${springcloud.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>${springcloud.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${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>
</profiles>
</project>由上面的pom.xml内容可见，account-service应用是个简单的web应用，和SpringCloud、spring-cloud-kubernetes都没有任何关系，和其他springboot唯一的不同就是用到了fabric8-maven-plugin插件，可以方便的将应用部署到kubernetes环境；
- application.yml内容如下，依旧很简单：
spring:
application:
name: account-service
server:
port: 8080- 对外提供服务的是AccountController ，方法getName返回了当前容器的hostname，方法health用于响应kubernetes的两个探针，方法ribbonPing用于响应使用了ribbon服务的调用方，它们会调用这个接口来确定当前服务是否正常：
@RestController
public class AccountController {
private static final Logger LOG = LoggerFactory.getLogger(AccountController.class);
private final String hostName = System.getenv("HOSTNAME");
/**
* 探针检查响应类
* @return
*/
@RequestMapping("/health")
public String health() {
return "OK";
}
@RequestMapping("/")
public String ribbonPing(){
LOG.info("ribbonPing of {}", hostName);
return hostName;
}
/**
* 返回hostname
* @return 当前应用所在容器的hostname.
*/
@RequestMapping("/name")
public String getName() {
return this.hostName
+ ", "
+ new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
}
}- 将上述工程的源码放在minikube机器上，确保maven设置正常，然后在pom.xml文件所在目录执行以下命令，即可编译构建工程并部署到kubernetes上：
mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes执行成功后控制台输出如下：
...
[INFO] Installing /usr/local/work/k8s/ribbon/spring-cloud-k8s-account-service/target/classes/META-INF/fabric8/kubernetes.json to /root/.m2/repository/com/bolingcavalry/account-service/0.0.1-SNAPSHOT/account-service-0.0.1-SNAPSHOT-kubernetes.json
[INFO]
[INFO] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ account-service <<<
[INFO]
[INFO]
[INFO] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ account-service ---
[INFO] F8: Using Kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/k8s/ribbon/spring-cloud-k8s-account-service/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-account-service.json
[INFO] Using namespace: default
[INFO] Updating Deployment from kubernetes.yml
[INFO] Updated Deployment: target/fabric8/applyJson/default/deployment-account-service.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: 11.941 s
[INFO] Finished at: 2019-06-16T19:00:51+08:00
[INFO] ------------------------------------------------------------------------- 检查kubernetes上的部署和服务是否正常：
[root@minikube spring-cloud-k8s-account-service]# kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
account-service 1/1 1 1 69m
[root@minikube spring-cloud-k8s-account-service]# kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
account-service NodePort 10.105.157.201 <none> 8080:32596/TCP 69m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8d- minikube的service命令可以得到指定服务的访问地址：
[root@minikube spring-cloud-k8s-account-service]# minikube service account-service --url
http://192.168.121.133:32596可见account-service的服务可以通过这个url访问：http://192.168.121.133:32596
- 用浏览器访问地址：http://192.168.121.133:32596/name ，如下图所示，可以正常访问account-service提供的服务：
现在account-service服务已经就绪，接下来是开发和部署web-service应用。
开发和部署Web-Service服务
Web-Service服务是个springboot应用，用到了spring-cloud-kubernetes提供的注册发现能力，以轮询的方式访问指定服务的全部pod：
- 通过maven创建一个springboot应用，artifactId是<font color="blue">web-service</font>，pom.xml内容如下，要重点关注的是<font color="blue">spring-cloud-starter-kubernetes-ribbon</font>的依赖：
<?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>web-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>web-service</name>
<description>Demo project for Spring Cloud service consumer run in kubernetes</description>
<properties>
<java.version>1.8</java.version>
<spring-boot.version>2.1.1.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>
<springcloud.version>2.1.1.RELEASE</springcloud.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<type>pom</type>
<scope>import</scope>
<version>${spring-boot.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-kubernetes-core</artifactId>
<version>${springcloud.kubernetes.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-kubernetes-discovery</artifactId>
<version>${springcloud.kubernetes.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-kubernetes-ribbon</artifactId>
<version>${springcloud.kubernetes.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-commons</artifactId>
<version>${springcloud.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<version>${springcloud.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>${springcloud.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
<version>${springcloud.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
<version>${springcloud.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${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>
</profiles>
</project>- application.yml的内容如下，增加了熔断的配置：
spring:
application:
name: web-service
server:
port: 8080
backend:
ribbon:
eureka:
enabled: false
client:
enabled: true
ServerListRefreshInterval: 5000
hystrix.command.BackendCall.execution.isolation.thread.timeoutInMilliseconds: 5000
hystrix.threadpool.BackendCallThread.coreSize: 5- 创建一个ribbon的配置类RibbonConfiguration：
package com.bolingcavalry.webservice;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AvailabilityFilteringRule;
import com.netflix.loadbalancer.IPing;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.PingUrl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
/**
* @Description: ribbon配置类
* @author: willzhao E-mail: zq2599@gmail.com
* @date: 2019/6/16 11:52
*/
public class RibbonConfiguration {
@Autowired
IClientConfig ribbonClientConfig;
/**
* 检查服务是否可用的实例，
* 此地址返回的响应的返回码如果是200表示服务可用
* @param config
* @return
*/
@Bean
public IPing ribbonPing(IClientConfig config){
return new PingUrl();
}
/**
* 轮询规则
* @param config
* @return
*/
@Bean
public IRule ribbonRule(IClientConfig config){
return new AvailabilityFilteringRule();
}
}- 应用启动类如下，注意增加了服务发现、熔断、ribbon的配置，还定义了restTemplte实例，注意@LoadBalanced注解：
package com.bolingcavalry.webservice;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
@EnableDiscoveryClient
@EnableCircuitBreaker
@RibbonClient(name="account-service", configuration = RibbonConfiguration.class)
public class WebServiceApplication {
public static void main(String[] args) {
SpringApplication.run(WebServiceApplication.class, args);
}
@LoadBalanced
@Bean
RestTemplate restTemplate(){
return new RestTemplate();
}
}- 远程调用account-service的http接口的逻辑被放进服务类AccountService中，注意URL中用的是服务名<font color="blue">account-service</font>：
package com.bolingcavalry.webservice;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* @Description: 这里面封装了远程调用account-service提供服务的逻辑
* @author: willzhao E-mail: zq2599@gmail.com
* @date: 2019/6/16 12:21
*/
@Service
public class AccountService {
@Autowired
private RestTemplate restTemplate;
@HystrixCommand(fallbackMethod = "getFallbackName" ,commandProperties = {
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000") })
public String getDataFromSpringCloudK8SProvider(){
return this.restTemplate.getForObject("http://account-service/name", String.class);
}
/**
* 熔断时调用的方法
* @return
*/
private String getFallbackName() {
return "Fallback"
+ ", "
+ new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
}
}- 最后是响应web请求的WebServiceController类，这里面调用了AccountService的服务，这样我们从web发起请求后，web-service就会远程调用account-service的服务：
package com.bolingcavalry.webservice;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
/**
* @Description: 测试用的controller，会远程调用account-service的服务
* @author: willzhao E-mail: zq2599@gmail.com
* @date: 2019/6/16 11:46
*/
@RestController
public class WebServiceController {
@Autowired
private AccountService accountService;
/**
* 探针检查响应类
* @return
*/
@RequestMapping("/health")
public String health() {
return "OK";
}
/**
* 远程调用account-service提供的服务
* @return 多次远程调返回的所有结果.
*/
@RequestMapping("/account")
public String account() {
StringBuilder sbud = new StringBuilder();
for(int i=0;i<10;i++){
sbud.append(accountService.getDataFromSpringCloudK8SProvider())
.append("<br>");
}
return sbud.toString();
}
}- 将上述工程的源码放在minikube机器上，确保maven设置正常，然后在pom.xml文件所在目录执行以下命令，即可编译构建工程并部署到kubernetes上：
mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes执行成功后控制台输出如下：
...
[INFO] Installing /usr/local/work/k8s/ribbon/spring-cloud-k8s-web-service/target/classes/META-INF/fabric8/kubernetes.json to /root/.m2/repository/com/bolingcavalry/web-service/0.0.1-SNAPSHOT/web-service-0.0.1-SNAPSHOT-kubernetes.json
[INFO]
[INFO] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ web-service <<<
[INFO]
[INFO]
[INFO] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ web-service ---
[INFO] F8: Using Kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/k8s/ribbon/spring-cloud-k8s-web-service/target/classes/META-INF/fabric8/kubernetes.yml
[INFO] Using namespace: default
[INFO] Creating a Service from kubernetes.yml namespace default name web-service
[INFO] Created Service: target/fabric8/applyJson/default/service-web-service.json
[INFO] Using namespace: default
[INFO] Creating a Deployment from kubernetes.yml namespace default name web-service
[INFO] Created Deployment: target/fabric8/applyJson/default/deployment-web-service.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: 12.792 s
[INFO] Finished at: 2019-06-16T19:24:21+08:00
[INFO] ------------------------------------------------------------------------- 检查kubernetes上的部署和服务是否正常：
[root@minikube spring-cloud-k8s-web-service]# kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
account-service 1/1 1 1 109m
web-service 1/1 1 1 18m
[root@minikube spring-cloud-k8s-web-service]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
account-service NodePort 10.105.157.201 <none> 8080:32596/TCP 109m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8d
web-service NodePort 10.99.211.179 <none> 8080:30519/TCP 18m- minikube的service命令可以得到指定服务的访问地址：
[root@minikube spring-cloud-k8s-web-service]# minikube service web-service --url
http://192.168.121.133:30519可见web-service的服务可以通过这个url访问：http://192.168.121.133:30519
- 用浏览器访问地址：http://192.168.121.133:30519/account ，如下图所示，页面上展示的内容都是web-service调用了account-service的接口返回的，证明kubernetes上的注册发现能力正常：
扩容验证ribbon轮询能力
虽然web-service可以正常调用account-service的服务，但始终访问的是一个pod，接下来我们就对account-service的pod进行扩容，将数量调整为2个，看看web-service是否可以轮询调用每个account-service的pod：
- 执行以下命令即可将pod数量调整为2个：
kubectl scale --replicas=2 deployment account-service- 检查account-service的pod，发现已经有两个了(account-service-5554576647-m29xr和account-service-5554576647-zwwml)：
[root@minikube spring-cloud-k8s-web-service]# kubectl get pods
NAME READY STATUS RESTARTS AGE
account-service-5554576647-m29xr 1/1 Running 0 53m
account-service-5554576647-zwwml 1/1 Running 0 20s
web-service-6d775855c7-7lkvr 1/1 Running 0 29m- 用浏览器访问地址：http://192.168.121.133:30519/account ，如下图所示，account-sercice返回的hostname已经变成了两种，和前面查到的pod的name一致，可见web-service的确是通过ribbon轮询访问了多个account-service的pod：
验证熔断能力
接下来验证web-service配置的熔断服务是否可以生效：
- 执行以下命令将account-service的deployment删除：
kubectl delete deployment account-service- 再浏览器访问地址：http://192.168.121.133:30519/account ，如下图所示，页面上的"Fallback"是配置的熔断方法返回的内容，可见熔断配置已经生效：
- 再回到web-service的pom.xml所在位置执行以下命令，这样会重新构建部署一次web-service服务：
mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes- 再浏览器访问地址：http://192.168.121.133:30519/account ，如下图所示，服务成功恢复：
至此，spring-cloud-kubernetes的服务发现和轮询实战(含熔断)就全部完成了，利用API Server提供的信息，spring-cloud-kubernetes将原生的kubernetes服务带给了SpringCloud应用，帮助传统微服务更好的融合在kubernetes环境中，如果您也在考虑将应用迁移到kubernetes上，希望本文能给您一些参考。
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