一、前言

1、什么是Eureka?

Eureka是Netflix开源的服务注册与发现框架,Eureka由两个组件组成:Eureka服务器和Eureka客户端。

Eureka Server提供服务注册服务,各个节点启动后,会在Eureka Server中进行注册,这样EurekaServer中的服务注册表中将会存储所有可用服务节点的信息,服务节点的信息可以在界面中直观的看到。

Eureka客户端是一个Java客户端,用来简化与服务器的交互、作为轮询负载均衡器,并提供服务的故障切换支持。

2、Eureka概览

Eureka服务注册与发现

行为 ken.io 的说明
1. Registry 服务启动时,Eureka客户端会将Service(ServiceName、IP、Port)注册到Eureka Server
2. Query 应用通过Eureka客户端调用注册在Eureka Server的服务时,会通过ServiceName查询到服务实例列表
3. Call 根据拿到的服务实例信息,通过负载均衡或其他策略访问指定服务实例
3、本篇环境信息
框架 版本
Spring Boot 2.0.0.RELEASE
Spring Cloud Finchley.BUILD-SNAPSHOT
JDK 1.8.x

二、搭建Eureka Server

  • 创建一个Spring Boot工程

使用maven-archtype-quickstart模板创建项目

IDEA Maven QuickStart 创建项目

说明
GroupId io.ken.springcloud.eurekaserver
ArtifactId eurekaserver
  • 在pom.xml加入相关依赖
<?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>

    <groupId>io.ken.springcloud.eurekaserver</groupId>
    <artifactId>eurekaserver</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>eurekaserver</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
    </parent>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.BUILD-SNAPSHOT</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>

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

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <repositories>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/libs-snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>

    <build>
        <finalName>eurekaserver</finalName>
    </build>

</project>
  • 配置启动类

修改\src\main\java\io\ken\springcloud\eurekaserver\App.java
基于Spring Boot创建启动类,添加上 ==@EnableEurekaServer== 注解

package io.ken.springcloud.eurekaserver;

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


@EnableEurekaServer
@SpringBootApplication
public class App {

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}
  • 配置Eureka Server

在\src\main下创建文件夹resources文件夹并设置为Resources Root

在resources文件夹下创建application.yml文件并配置Eureka Server

server:
  port: 8800

spring:
  application:
    name: EurekaServer

eureka:
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://localhost:${server.port}/eureka/

Eureka默认会以客户端来注册自己,所以registerWithEureka、fetchRegistry要配置为false。

  • 启动Eureka Server

启动项目后,访问:http://localhost:8800/ ,可以看到下面的页面,其中还没有发现任何服务。

Eureka Server Portal

三、搭建服务并注册(Eureka Client)

  • 创建一个Spring Boot工程

使用maven-archtype-quickstart模板创建项目

IDEA Maven QuickStart 创建项目

说明
GroupId io.ken.springcloud.helloservice
ArtifactId helloservice
  • 在pom.xml加入相关依赖
<?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>

    <groupId>io.ken.springcloud.helloservice</groupId>
    <artifactId>helloservice</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>helloservice</name>
    <url>http://ken.io</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
    </parent>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.BUILD-SNAPSHOT</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <repositories>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/libs-snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>

    <build>
        <finalName>helloservice</finalName>
    </build>

</project>
  • 配置启动类

修改\src\main\java\io\ken\springcloud\eurekaserver\App.java
基于Spring Boot创建启动类,添加上 ==@EnableDiscoveryClient== 注解

package io.ken.springcloud.helloservice;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@SpringBootApplication
public class App {

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}
  • 创建服务示例

在\src\main\java\io\ken\springcloud\helloservice创建package:controller
然后创建HelloController.java

package io.ken.springcloud.helloservice.controller;

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

@RestController
public class HelloController {

    @Autowired
    DiscoveryClient discoveryClient;

    @RequestMapping("/")
    public Object index() {
        return "hello service";
    }

    @RequestMapping("/info")
    public Object info() {
        return discoveryClient.getServices();
    }
}
  • 配置Eureka Client

在\src\main下创建文件夹resources文件夹并设置为Resources Root

在resources文件夹下创建application.yml文件并配置Eureka Client

server:
  port: 8601

spring:
  application:
    name: helloservice

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8800/eureka/
  • 启动HelloService

项目成功启动后,访问 http://localhost:8601 ,或者 http://localhost:8601/info
查看是否正常启动

访问 http://localhost:8800 ,会发现服务已注册

eureka instance registered

搞定!

四、备注

  • 本篇示例代码

https://github.com/ken-io/springcloud-course/tree/master/chapter-01