二、eureka注册中心集群

Spring Cloud 2.x系列之 eureka注册中心集群
1、 Eureka作为spring cloud的服务发现与注册中心，在整个的微服务体系中，处于核心位置。单机模式下的eureka服务，显然不能满足高可用的实际生产环境，这就要求配置一个能够应对各种突发情况，具有较强容灾能力的eureka服务。Eureka通过“伙伴机制”实现高可用。每一台Eureka都需要在配置中指定另外两个Eureka的地址伙伴，Eureka启动时会向自己的伙伴节点获取当前已经存在的注册表，这样在向Eureka集群中新加机器时就不需要担心注册表的不完整。
2、 新建三个maven项目，分别为sc-eureka-cluster-server-node1，sc-eureka-cluster-server-node2，sc-eureka-cluster-server-node3。项目结构如下：

备注：pom.xml和EurekaServerApplication.java的内容给单机模式是一模一样的，请参考上篇文章。
3、 主要看下bootstap.yml或者application.yml文件的改动
sc-eureka-cluster-server-node1

spring:
  application:
    name: sc-eureka-cluster-server-node1
    
server:
  port: 5001
  
eureka:
  instance:
    hostname: sc-eureka-cluster-server-node1
    lease-renewal-interval-in-seconds: 30
    lease-expiration-duration-in-seconds: 30
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://sc-eureka-cluster-server-node2:5002/eureka/,http://sc-eureka-cluster-server-node3:5003/eureka/

sc-eureka-cluster-server-node2

spring:
  application:
    name: sc-eureka-cluster-server-node2
    
server:
  port: 5002
  
eureka:
  instance:
    hostname: sc-eureka-cluster-server-node2
    lease-renewal-interval-in-seconds: 30
    lease-expiration-duration-in-seconds: 30
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://sc-eureka-cluster-server-node1:5001/eureka/,http://sc-eureka-cluster-server-node3:5003/eureka/

sc-eureka-cluster-server-node3

spring:
  application:
    name: sc-eureka-cluster-server-node3
    
server:
  port: 5003
  
eureka:
  instance:
    hostname: sc-eureka-cluster-server-node3
    lease-renewal-interval-in-seconds: 30
    lease-expiration-duration-in-seconds: 30
    prefer-ip-address: true
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://sc-eureka-cluster-server-node1:5001/eureka/,http://sc-eureka-cluster-server-node2:5001/eureka/

4、 配置host文件C:\Windows\System32\drivers\etc\hosts

127.0.0.1 sc-eureka-cluster-server-node1
127.0.0.1 sc-eureka-cluster-server-node2
127.0.0.1 sc-eureka-cluster-server-node3

5、 分别启动EurekaServerApplication.java
sc-eureka-cluster-server-node1的日志：

sc-eureka-cluster-server-node2的日志：

sc-eureka-cluster-server-node3的日志

如果出现上面圈住的日志说明启动成功

6、 在浏览器分别访问
http://sc-eureka-cluster-server-node1:5001/

http://sc-eureka-cluster-server-node2:5002/

http://sc-eureka-cluster-server-node3:5002/

下面列出几个重要的配置项类：

org.springframework.boot.autoconfigure.web.ServerProperties
org.springframework.cloud.netflix.eureka.EurekaInstanceConfigBean
com.netflix.eureka.EurekaServerConfig
com.netflix.eureka.DefaultEurekaServerConfig
org.springframework.cloud.netflix.eureka.server.EurekaServerConfigBean
com.netflix.discovery.EurekaClientConfig
com.netflix.discovery.DefaultEurekaClientConfig
org.springframework.cloud.netflix.eureka.EurekaClientConfigBean

源码：

https://gitee.com/hjj520/spring-cloud-2.x

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