Eureka集群

Eureka集群搭建

高可用集群配置

当注册中心扛不住高并发的时候，这时候 要用集群来扛；

普通操作

我们再新建两个module  microservice-eureka-server-2002  microservice-eureka-server-2003

1、pom.xml 把依赖加下；

<?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.</modelVersion>
    <parent>
        <groupId>com.jt</groupId>
        <artifactId>microservice</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>microservice-eureka-server-</artifactId>

    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--  修改后立即生效，热部署  -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2、2002  2003的主启动类EurekaServerApplication_2002，EurekaServerApplication_2003复制修改下；

package com.jt.microserviceeurekaserver2002;

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

@EnableEurekaServer
@SpringBootApplication
public class MicroserviceEurekaServer2002Application {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceEurekaServer2002Application.class, args);
    }

}

3、前面单机的时候 eureka注册中心实例名称 是localhost，现在是集群，不能三个实例都是localhost，这里复杂的办法是搞三个虚拟机，麻烦，这里有简单办法，直接配置本机hosts，来实现本机域名映射；

找到 C:\Windows\System32\drivers\etc  打开hosts，加配置

127.0.0.1  eureka2001.jt.com
127.0.0.1  eureka2002.jt.com
127.0.0.1  eureka2003.jt.com

修改三个项目的application.yml文件，主要是修改 hostname和defaultZone，

2001修改：

server:
  port:
  context-path: /

eureka:
  instance:
    hostname: eureka2001.jt.com
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka2002.jt.com:2002/eureka/,http://eureka2003.jt.com:2003/eureka/ # 集群

2002

server:
  port:
  context-path: /

eureka:
  instance:
    hostname: eureka2002.jt.com
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka2001.jt.com:2001/eureka/,http://eureka2003.jt.com:2003/eureka/

2003

server:
  port:
  context-path: /

eureka:
  instance:
    hostname: eureka2003.jt.com
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka2001.jt.com:2001/eureka/,http://eureka2002.jt.com:2002/eureka/

骚操作

上面eureka服务搭建，除了yml文件不一样，其他文件都一样，那么我们有什么办法能够将多个eureka服务集合到一个工程中去呢？

创建一个microservice-eureka-server（三合一）子工程

Pom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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.</modelVersion>
    <parent>
        <groupId>com.jt</groupId>
        <artifactId>microservice</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>microservice-eureka-server</artifactId>

    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--  修改后立即生效，热部署  -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Yml文件

---
server:
  port:
  context-path: /
eureka:
  instance:
    hostname: eureka2001.jt.com
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka2002.jt.com:2002/eureka/,http://eureka2003.jt.com:2003/eureka/
spring:
  profiles: eureka2001
---
server:
  port:
  context-path: /
eureka:
  instance:
    hostname: eureka2002.jt.com
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka2001.jt.com:2001/eureka/,http://eureka2003.jt.com:2003/eureka/
spring:
  profiles: eureka2002
---
server:
  port:
  context-path: /
eureka:
  instance:
    hostname: eureka2003.jt.com
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka2001.jt.com:2001/eureka/,http://eureka2002.jt.com:2002/eureka/
spring:
  profiles: eureka2003

启动类MicroserviceEurekaServerApplication.java

package com.jt.microserviceeurekaserver;

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

@EnableEurekaServer
@SpringBootApplication
public class MicroserviceEurekaServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceEurekaServerApplication.class, args);
    }

}

跑起来的效果跟普通操作的效果是一致的；

Eureka自我保护机制

开发环境，我们经常会遇到这个红色的警告；

当我们长时间为访问服务以及变更服务实例名称的时候，就会出现这个红色警告；

默认情况，如果服务注册中心再一段时间内没有接收到某个微服务实例的心跳，服务注册中心会注销该实例（默认90秒）。

由于正式环境，经常会有网络故障，网络延迟问题发生，服务和注册中心无法正常通信，此时服务是正常的，不应该注销该服务，Eureka这时候，就通过“自我保护模式”来解决问题，当短时间和服务失去通信时，保留服务信息，当恢复网络和通信时候，退出“自我保护模式”；

通过“自我保护模式”，使Eureka集群更加的健壮和稳定；