spring cloud eureka

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2023-12-01

eureka 用以服务发现、服务注册，比较流行的有consul

简介

eureka为netflix开源软件，分为三个部分：

eureka服务:用以提供服务注册、发现，已一个war的形式提供 http://search.maven.org/ 或者编译源码，将war拷贝进tomcat即可提供服务
eureka-server: 相对client端的服务端，为客户端提供服务，通常情况下为一个集群
eureka-client:客户端，通过向eureka服务发现注册的可用的eureka-server，向后端发送请求

spring cloud eureka

spring cloud eureka 分为两部分

@EnableEurekaClient: 该注解表明应用既作为eureka实例又为eureka client 可以发现注册的服务
@EnableEurekaServer: 该注解表明应用为eureka服务，有可以联合多个服务作为集群，对外提供服务注册以及发现功能

client 端

pom.xml

<?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">
    <parent>
        <artifactId>springcloud</artifactId>
        <groupId>com.lkl.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>eureka</artifactId>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-netflix</artifactId>
                <version>1.0.7.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <!--表示为web工程-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--暴露各种指标-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

    </dependencies>
</project>

启动应用 Application.java

package com.lkl.springcloud.eureka;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by liaokailin on 16/4/30.
 */
@SpringBootApplication
@EnableEurekaClient
@RestController
@EnableAutoConfiguration
public class Application {
    @RequestMapping("/")
    public String home() {
        return "Hello world";
    }

    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }
}

创建配置application.properties

server.port=9090
spring.application.name=eureka.client
#eureka.client.serviceUrl.defaultZone=http://120.76.145.187:8080/eureka-server-1.4.6/v2/
eureka.client.serviceUrl.defaultZone=http://localhost:7070/eureka/
eureka.instance.appname=eureka.client.01
#eureka.client.registerWithEureka=true
#eureka.client.fetchRegistry=true

eureka.client.serviceUrl.defaultZone 配置eureka服务地址

server

pom.xml

<?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">
    <parent>
        <artifactId>springcloud</artifactId>
        <groupId>com.lkl.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>eureka-server</artifactId>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-netflix</artifactId>
                <version>1.0.7.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <!--表示为web工程-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--暴露各种指标-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>


    </dependencies>

</project>

启动应用Application.java

package com.lkl.springcloud.eureka;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

/**
 * Created by liaokailin on 16/4/30.
 */
@EnableEurekaServer
@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }

}

配置application.yml

server:
  port: 7070
spring:
  application:
    name: server-01
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:7070/eureka/
  instance:
    metadataMap:
      instanceId: ${spring.application.name}:${spring.application.instance_id:${random.value}}

spring.application.name表示应用名称，集群名称需要一致 defaultZone表示向自身注册，例子中有三个server节点构成集群，其余两个两个节点也向该端口注册 instanceId 表示eureka instance 标识，需要唯一，如果不配置，多个节点最终只会有一个生效

同样的配置第二个节点,第三个节点

启动所有服务端应用访问 http://localhost:7070 可以查看eureka注册服务信息

访问 http://localhost:7070/eureka/apps 可以查看metadata

服务发现

在客户端创建Component

DiscoveryService.java

package com.lkl.springcloud.eureka;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * Created by liaokailin on 16/4/30.
 */
@Component
@RestController
public class DiscoveryService {

    @Autowired
    private DiscoveryClient discoveryClient;

    @RequestMapping("/discovery")
    public String doDiscoveryService(){
        StringBuilder buf = new StringBuilder();
        List<String> serviceIds = discoveryClient.getServices();
        if(!CollectionUtils.isEmpty(serviceIds)){
            for(String s : serviceIds){
                System.out.println("serviceId:" + s);
                List<ServiceInstance> serviceInstances =  discoveryClient.getInstances(s);
                if(!CollectionUtils.isEmpty(serviceInstances)){
                    for(ServiceInstance si:serviceInstances){
                        buf.append("["+si.getServiceId() +" host=" +si.getHost()+" port="+si.getPort()+" uri="+si.getUri()+"]");
                    }
                }else{
                    buf.append("no service.");
                }
            }
        }


        return buf.toString();
    }

}

访问 http://localhost:9090/discovery 实现服务发现。