【Spring Cloud Kubernetes】使用k8s原生service实现服务注册和发现

约定不等于承诺〃 2023-10-12 14:02 30阅读 0赞

@TOC

## 背景 ##

现在微服务开发模式应用的越来越广泛，注册中心`Eureka`也逐渐被其它注册中心产品替代，比如阿里出品的`Nacos`。随着云原生相关技术的普及，`k8s`迅猛发展，我们把`K8s`中的`Pod`暴露给外部访问，通过少了`Service`，这也是今天的主角。

有没有发现，其实`Service`已经解决了`Pod`的注册与发现的问题，并且也实现了负载，我们在基于云原生开发微服务的时候，可以利用`Service`的能力，获取后面的`Pod`列表，通过`Ribbon`等客户端负载对`Pod`发起调用，也可以直接利用`Service`的负载能力进行调用。`k8s`内部会使用`ETCD`服务维护这些信息的变化。`Spring`官网也为`k8s`提供了一套原生的支持子项目，那就是`Spring Cloud Kubernetes`。

## 本地开发环境说明 ##

<table> 
 <thead> 
  <tr> 
   <th align="left">开发依赖</th> 
   <th align="left">版本</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">Spring Boot</td> 
   <td align="left">3.1.0</td> 
  </tr> 
  <tr> 
   <td align="left">Spring Cloud</td> 
   <td align="left">2022.0.3</td> 
  </tr> 
  <tr> 
   <td align="left">JDK</td> 
   <td align="left">20</td> 
  </tr> 
 </tbody> 
</table>

## 本地非K8s环境如何进行开发调试 ##

在传统的微服务开发中，会借助Nacos注册中心，现在没有Nacos了，本地通过Fabric8，底层与k8s的API Server进行交互，获取集群内的资源信息

## 主要pom.xml依赖 ##

<dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-bootstrap</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-kubernetes-fabric8-all</artifactId>
            </dependency>
        </dependencies>

## 启动类 ##

*  使用`@EnableDiscoveryClient`开启服务发现注册功能
 *  使用`@EnableFeignClients`启用`@FeignClient`功能

package com.wen3.springcloudk8s.demo;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    @EnableFeignClients
    @EnableDiscoveryClient
    @SpringBootApplication
    public class DemoSpringCloudKubernetesApplication {
        
    
        public static void main(String[] args) {
        
            SpringApplication.run(DemoSpringCloudKubernetesApplication.class, args);
        }
    }

## 写一个Feign的调用 ##

*  如果多个微服务都是部署在集群内，可以通过`service`相互调用
 *  如果是本地调集群内的微服务，可以指定`url`参数，优级级比`name`要高，`url`可以指定为集群内`service`暴露的外部端点

package com.wen3.springcloudk8s.demo.feign;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import java.util.Map;
    
    @FeignClient(name = "springboot-min", url = "${springboot-min.url:}")
    public interface SpringMinFeignClient {
        
    
        @RequestMapping(path = "/hello")
        String hello(@RequestBody(required = false) Map<String,Object> bodyMap);
    }

## 写一个Controller ##

package com.wen3.springcloudk8s.demo.controller;
    
    import com.wen3.springcloudk8s.demo.feign.SpringMinFeignClient;
    import io.fabric8.kubernetes.api.model.ConfigMap;
    import io.fabric8.kubernetes.api.model.ConfigMapList;
    import io.fabric8.kubernetes.client.KubernetesClient;
    import io.fabric8.kubernetes.client.dsl.ApiextensionsAPIGroupDSL;
    import io.fabric8.kubernetes.client.dsl.MixedOperation;
    import jakarta.annotation.Resource;
    import org.springframework.cloud.client.discovery.DiscoveryClient;
    import org.springframework.cloud.kubernetes.commons.KubernetesClientProperties;
    import org.springframework.cloud.kubernetes.fabric8.discovery.KubernetesDiscoveryClient;
    import org.springframework.http.MediaType;
    import org.springframework.web.bind.annotation.*;
    
    import java.util.Enumeration;
    import java.util.List;
    import java.util.Map;
    
    @RequestMapping(path = "/k8s")
    @RestController
    public class K8sController {
        
    
        @Resource
        private DiscoveryClient discoveryClient;
        @Resource
        private SpringMinFeignClient springMinFeignClient;
        @Resource
        private KubernetesClientProperties kubernetesClientProperties;
    
        @GetMapping("/services")
        public List<String> getServices() {
        
            return discoveryClient.getServices();
        }
    
        @RequestMapping(path = "/hello")
        public String hello(@RequestBody(required = false) Map<String,Object> bodyMap) {
        
            return springMinFeignClient.hello(bodyMap);
        }
    }

## bootstrap.yaml ##

debug: true
    logging:
      level:
        root: debug
    
    spring:
      application:
        name: spring-cloud-k8s-demo
      cloud:
        kubernetes:
          client:
            namespace: demo
            master-url: https://k8s-cluster-ip:6443
            trust-certs: true
            oauth-token: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
          discovery:
            enabled: true
            # all-namespaces为true，代表在整个集群范围查找资源，可能没有权限
            all-namespaces: false
            namespaces:
              - cop
          reload:
            enabled: true
            mode: event
    #        mode: polling
    #        period: 5000
          loadbalancer:
            enabled: true
            mode: service
            clusterDomain: cluster.local
            portName: rest
    
    
    springboot-min:
      url: http://10.79.193.64:8880

## k8s部署springboot-min ##

写一个最简单的微服务，提供一个/hello接口，部署到k8s，这一步直接省略。