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

@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

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>
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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);
    }
}
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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);
}
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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);
    }
}
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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
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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。