本文实战 Eureka Server 集群。
- 集群工程的配置
- docker-compose 编排示例（实际生产环境中，肯定要放在不同的物理机上）
一、Eureka Server 工程
工程代码很简单，工程代码主要包含：
1、pom.xml 文件
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.8.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.shanhy</groupId>
<artifactId>shanhy-eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>shanhy-eureka</name>
<description>Eureka project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.SR3</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<finalName>${project.name}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2、启动主Java类
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class ShanhyEurekaApplication {
public static void main(String[] args) {
SpringApplication.run(ShanhyEurekaApplication.class, args);
}
}
3、配置文件 application.yml
spring:
application:
name: shanhy-eureka
---
spring:
profiles: eureka-server1
server:
port: 8761
eureka:
server:
enable-self-preservation: false # 开发环境关掉保护机制,快速发现已经挂掉的服务，生产环境需要设置为true提升服务稳定性
instance:
hostname: eureka-server1
prefer-ip-address: true
instance-id: ${spring.application.name}:${spring.cloud.client.ip-address}:${spring.application.instance_id:${server.port}}
client:
serviceUrl:
defaultZone: http://eureka-server2:8762/eureka/,http://eureka-server3:8763/eureka/
register-with-eureka: true
---
spring:
profiles: eureka-server2
server:
port: 8762
eureka:
server:
enable-self-preservation: false # 开发环境关掉保护机制,快速发现已经挂掉的服务，生产环境需要设置为true提升服务稳定性
instance:
hostname: eureka-server2
prefer-ip-address: true
instance-id: ${spring.application.name}:${spring.cloud.client.ip-address}:${spring.application.instance_id:${server.port}}
client:
serviceUrl:
defaultZone: http://eureka-server1:8761/eureka/,http://eureka-server3:8763/eureka/
register-with-eureka: true
---
spring:
profiles: eureka-server3
server:
port: 8763
eureka:
server:
enable-self-preservation: false # 开发环境关掉保护机制,快速发现已经挂掉的服务，生产环境需要设置为true提升服务稳定性
instance:
hostname: eureka-server3
prefer-ip-address: true
instance-id: ${spring.application.name}:${spring.cloud.client.ip-address}:${spring.application.instance_id:${server.port}}
client:
serviceUrl:
defaultZone: http://eureka-server1:8761/eureka/,http://eureka-server2:8762/eureka/
register-with-eureka: true
4、打包和启动
先使用 mvn package 打包
然后配置本地 host 用于测试
127.0.0.1 eureka-server1
127.0.0.1 eureka-server2
127.0.0.1 eureka-server3
最后指定不同 profile 启动3个集群节点
java -jar shanhy-eureka.jar --spring.profiles.active=eureka-server1
java -jar shanhy-eureka.jar --spring.profiles.active=eureka-server2
java -jar shanhy-eureka.jar --spring.profiles.active=eureka-server3
在没有全部都启动完成之前，控制台会报错的，意思是还有集群节点服务链接不上。
完全启动后，浏览器分别访问 http://localhost:8761、http://localhost:8762、http://localhost:8763 可以查看集群状态。
5、docker-compose 编排示例
前提是你的工程已经使用 dockerfile 构建完成（这个本文不演示）
假设我们构建的镜像名为 xzxiaoshan/eureka-server:latest
然后创建 docker-compose.yml 内容如下：
version: "3"
services:
eureka-server1:
image: xzxiaoshan/eureka-server:latest
container_name: eureka-server1
hostname: eureka-server1
networks:
- eureka-net
ports:
- "8761:8761"
environment:
- spring.profiles.active=eureka-server1
eureka-server2:
image: xzxiaoshan/eureka-server:latest
hostname: eureka-server2
container_name: eureka-server2
networks:
- eureka-net
ports:
- "8762:8762"
environment:
- spring.profiles.active=eureka-server2
eureka-server3:
image: xzxiaoshan/eureka-server:latest
hostname: eureka-server3
container_name: eureka-server3
networks:
- eureka-net
ports:
- "8763:8763"
environment:
- spring.profiles.active=eureka-server3
networks:
eureka-net:
driver: bridge
这个 docker-compose 文件意在示范使用docker 启动eureka服务，实际上这是一个假集群，因为在实际生产中，集群肯定落实在不同的物理机上。不同的物理机之间的docker访问，你可能需要参考一下文章 《Docker 跨主机网络通讯 flannel+etcd》 。
如果你用了 flannel+etcd 方案，建议所有服务都使用 docker run 来启动，因为docker-compose 会强制给你管理网络，会出现一些问题。
3个eureka 服务实例的启动脚本示例：
docker run -itd --name eureka-server1 -p 8761:8761 -e spring.profiles.active=eureka-server1 -e eureka.client.serviceUrl.defaultZone=http://192.168.1.164:8762/eureka/,http://192.168.1.164:8763/eureka/ 192.168.1.163:81/gukesoft/shanhy-eureka:latest
docker run -itd --name eureka-server2 -p 8762:8762 -e spring.profiles.active=eureka-server2 -e eureka.client.serviceUrl.defaultZone=http://192.168.1.164:8761/eureka/,http://192.168.1.164:8763/eureka/ 192.168.1.163:81/gukesoft/shanhy-eureka:latest
docker run -itd --name eureka-server3 -p 8763:8763 -e spring.profiles.active=eureka-server3 -e eureka.client.serviceUrl.defaultZone=http://192.168.1.164:8761/eureka/,http://192.168.1.164:8762/eureka/ 192.168.1.163:81/gukesoft/shanhy-eureka:latest
PS：如果你上了K8S和ServiceMesh，Eureka 可能你就不需要了。
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