Eureka编程

在一些场景下，我们需要监听eureka服务中心的一些状态，譬如某个微服务挂掉了，我们希望能监听到，并给管理员发送邮件通知或钉钉告警。

一、Eureka的监听事件，可以用来监控、告警
EurekaInstanceRegisteredEvent 服务注册事件
EurekaInstanceRenewedEvent 服务续约事件，续约即心跳
EurekaRegistryAvailableEvent Eureka注册中心启动事件
EurekaServerStartedEvent Eureka Server启动事件
EurekaInstanceCanceledEvent 服务下线事件

package com.mimaxueyuan.cloud.eureka.event;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.netflix.eureka.server.event.EurekaInstanceCanceledEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaInstanceRegisteredEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaInstanceRenewedEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaRegistryAvailableEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaServerStartedEvent;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

import com.netflix.appinfo.InstanceInfo;

@Component
public class KevinEventLinstener {

    private Logger logger = LoggerFactory.getLogger(KevinEventLinstener.class);

    @EventListener
    public void listen(EurekaInstanceRegisteredEvent event) {
        InstanceInfo instanceInfo = event.getInstanceInfo();
        String ip = instanceInfo.getIPAddr();
        String id = instanceInfo.getInstanceId();
        logger.info(">>>>>>>>" + id + "已经注册到Eureka,IP=" + ip);
    }

    @EventListener
    public void listen(EurekaInstanceRenewedEvent event) {
        InstanceInfo instanceInfo = event.getInstanceInfo();
        String id = instanceInfo.getInstanceId();
        logger.info(">>>>>>>>"+id+"续约事件触发...");
    }

    @EventListener
    public void listen(EurekaRegistryAvailableEvent event) {
        logger.info(">>>>>>>>注册中心启动事件触发...");
    }

    @EventListener
    public void listen(EurekaServerStartedEvent event) {
        logger.info(">>>>>>>>EurekaServer启动事件触发...");
    }
    
    @EventListener
    public void listen(EurekaInstanceCanceledEvent  event) {
        String id = event.getServerId();
        logger.info(">>>>>>>>"+id+"从Eureka下线...");
    }

}

二、注解@DiscoveryClient与@EurekaDiscoveryClient

package com.mimaxueyuan.producer.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class EurekaController {

    // 以下两个客户端类,用哪个都可以,DiscoveryClient抽象程度更高,是一个接口,EurekaDiscoveryClient只是他的抽象类
    @Autowired
    private DiscoveryClient discoveryClient;

    // eureka使用展示
    @GetMapping("/eureka/test")
    public String eureka() {
        System.out.println("eureka使用展示:/eureka/get---start");

        // ----------------- 以下的代码使用DiscoveryClient-------------------
        // 查询所有注册到Eureka上的服务:
        System.out.println("[discoveryClient]-查询所有注册到Eureka上的服务:");
        for (String string : discoveryClient.getServices()) {
            System.out.println(string);
        }

        // 查询某一个provider的所有Service实例
        System.out.println("[discoveryClient]-查询某一个provider的所有Service实例");
        List<ServiceInstance> instances = discoveryClient.getInstances("mima-cloud-producer");
        for (ServiceInstance instance : instances) {
            System.out.println("host:" + instance.getHost() + ",port:" + instance.getPort() + ",serviceId=" + instance.getServiceId() + ",uri=" + instance.getUri());
            System.out.println("metadata=" + instance.getMetadata());
        }

        // TODO 已经不推荐使用
        ServiceInstance localServiceInstance = discoveryClient.getLocalServiceInstance();
         
        return "eureka's demo, please to see console output";
    }

}