Spring cloud搭建Eureka高可用注册中心

注册中心在微服务中是必不可少的一部分，主要用来实现服务自治的功能，本文则主要记载使用Netflix提供的Eureka作为注册中心，来实现服务自治的功能。

实际上Eureka的集群搭建方法很简单：每一台Eureka只需要在配置中指定另外多个Eureke的地址，就可以实现一个集群的搭建了

例如：

两节点

　　-- 节点1注册到节点2

　　--节点2注册到节点1

三节点

　　--节点1注册到节点2,3

　　--节点2注册到节点1,3

　　--节点3注册到节点1,2

我做的是两个Eureka节点构建注册中心，然后一个producer和一个customer分别进行提供服务和请求服务：见图

节点1：

先新建一个Maven项目，添加依赖(基于jdk11,如果不是jdk11,可以不添加)

pom.xml主要代码

 <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>1.5.4.RELEASE</version>
         <relativePath/>
     </parent>

     <properties>
         <java.version>11</java.version>
     </properties>

     <!-- 依赖 -->
     <dependencies>
         <!-- Eureka -->
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-eureka-server</artifactId>
         </dependency>

         <!--java 11 缺少的模块 javax.xml.bind-->
         <dependency>
             <groupId>javax.xml.bind</groupId>
             <artifactId>jaxb-api</artifactId>
             <version>2.3.0</version>
         </dependency>
         <dependency>
             <groupId>com.sun.xml.bind</groupId>
             <artifactId>jaxb-impl</artifactId>
             <version>2.3.0</version>
         </dependency>
         <dependency>
             <groupId>org.glassfish.jaxb</groupId>
             <artifactId>jaxb-runtime</artifactId>
             <version>2.3.0</version>
         </dependency>
         <dependency>
             <groupId>javax.activation</groupId>
             <artifactId>activation</artifactId>
             <version>1.1.1</version>
         </dependency>

         <!-- 添加 Spring-Security 不需要则不添加-->
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-security</artifactId>
         </dependency>
     </dependencies>

     <!-- Spring Cloud -->
     <dependencyManagement>
         <dependencies>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-dependencies</artifactId>
                 <version>Dalston.SR4</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
         </dependencies>
     </dependencyManagement>

application.yml

---
server:
  ###启动端口
  port:
spring:
  ###启动的配置文件名
  profiles: eureka1
  ###应用名
  application:
    name: master
eureka:
  instance:
    hostname: eureka1
  client:
    ###不向注册中心注册自己
    register-with-eureka: false
    ###不需要检索服务
    fetch-registry: false
    serviceUrl:
      defaultZone: http://127.0.0.1:8762/eureka/
  server:
    ###关闭自我保护模式
    enable-self-preservation: false
    ###清理的间隔为5s
    eviction-interval-timer-in-ms:
security:
  basic:
    ###暂时关闭安全认证
    enabled: false

---
server:
  ###启动端口
  port:
spring:
  ###启动的配置文件名
  profiles: eureka2
  application:
    ###应用名
    name: slaveone
eureka:
  instance:
    hostname: eureka2
  client:
    ###不向注册中心注册自己
    register-with-eureka: false
    ###不需要检索服务
    fetch-registry: false
    serviceUrl:
      defaultZone: http://127.0.0.1:8761/eureka/
  server:
    ###关闭自我保护模式
    enable-self-preservation: false
    ###清理的间隔为5s
    eviction-interval-timer-in-ms:
security:
  basic:
    ###暂时关闭安全认证
    enabled: false

启动类：EurekaServerApplication.class

 @EnableEurekaServer
 @SpringBootApplication
 public class EurekaServerApplication {

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

启动参数 IDEA设置    --spring.profiles.active=eureka1

点击这个：

同理另外一个节点的启动类，application.yml和pom.xml文件与节点1相同

启动参数改为--spring.profiles.active=eureka2

此时，浏览器输入 http://127.0.0.1:8761/发现如下：

至此注册中心已经搭建完成

producer服务注册：

主要的pom.xml文件

     <properties>
         <java.version>11</java.version>
     </properties>

     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>1.5.4.RELEASE</version>
         <relativePath/>
     </parent>

     <!-- 依赖 -->
     <dependencies>
         <!-- Eureka -->
         <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-eureka</artifactId>
         </dependency>
         <!--java 11 缺少的模块 javax.xml.bind-->
         <dependency>
             <groupId>javax.xml.bind</groupId>
             <artifactId>jaxb-api</artifactId>
             <version>2.3.0</version>
         </dependency>
         <dependency>
             <groupId>com.sun.xml.bind</groupId>
             <artifactId>jaxb-impl</artifactId>
             <version>2.3.0</version>
         </dependency>
         <dependency>
             <groupId>org.glassfish.jaxb</groupId>
             <artifactId>jaxb-runtime</artifactId>
             <version>2.3.0</version>
         </dependency>
         <dependency>
             <groupId>javax.activation</groupId>
             <artifactId>activation</artifactId>
             <version>1.1.1</version>
         </dependency>

         <!-- Actuator 健康检查 -->
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-actuator</artifactId>
         </dependency>
     </dependencies>

     <!-- Spring Cloud -->
     <dependencyManagement>
         <dependencies>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-dependencies</artifactId>
                 <version>Dalston.SR4</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
         </dependencies>
     </dependencyManagement>

application.properties文件：

spring.application.name=producer
server.port=8081
eureka.client.service-url.defaultZone=http://127.0.0.1:8761/eureka/,http://127.0.0.1:8762/eureka/

### 配置健康检查的信息
eureka.client.healthcheck.enabled=true
### 默认30s
eureka.instance.lease-renewal-interval-in-seconds=5
### 默认90秒
eureka.instance.lease-expiration-duration-in-seconds=5

 @RestController
 @RequestMapping("/home")
 public class HomeController {

     @GetMapping("/hello")
     public String hello(){
         return "hello";
     }
 }

基本的control类和启动类

 @SpringBootApplication
 @EnableDiscoveryClient
 public class ProduceServiceApplication {
     public static void main(String[] args){
         SpringApplication.run(ProduceServiceApplication.class, args);
     }
 }

启动之后再看Eureka注册中心：两个节点应该都有

访问   http:127.0.0.1:8081/home/hello  发现正常返回字符串

此时

搭建customer请求服务

pom.xml 和application.properties文件

<properties>
        <java.version>11</java.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
        <relativePath/>
    </parent>

    <!-- 依赖 -->
    <dependencies>
        <!-- Eureka -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <!--java 11 缺少的模块 javax.xml.bind-->
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jaxb</groupId>
            <artifactId>jaxb-runtime</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>javax.activation</groupId>
            <artifactId>activation</artifactId>
            <version>1.1.1</version>
        </dependency>

        <!-- Actuator 健康检查 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

    <!-- Spring Cloud -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR4</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

spring.application.name=customer
server.port=
eureka.client.service-url.defaultZone=http://127.0.0.1:8761/eureka/,http://127.0.0.1:8762/eureka/

### 配置健康检查的信息
eureka.client.healthcheck.enabled=true
### 默认30s
eureka.instance.lease-renewal-interval-in-seconds=
### 默认90秒
eureka.instance.lease-expiration-duration-in-seconds=

获取RestTemplate的类：

 @Configuration
 public class BeanConfiguration {

     @Bean
     @LoadBalanced
     public RestTemplate getRestTemplate(){
         return new RestTemplate();
     }
 }

control类

 @RestController
 @RequestMapping("/customer/")
 public class CustomerServiceController {

     @Autowired
     private RestTemplate restTemplate;

     @GetMapping("/callHello")
     public String callHello(){
         return restTemplate.getForObject("http://producer/home/hello", String.class);
     }
 }

启动类：

 @SpringBootApplication
 @EnableDiscoveryClient
 public class CustomerMainApplication {
     public static void main(String[] args){
         SpringApplication.run(CustomerMainApplication.class, args);
     }
 }

首先，正常情况下访问   http://localhost:8082/customer/callHello

然后停掉节点1，继续访问看是否成功：

请求正常

重新启动节点1，查看节点2的日志：

节点2在丢失节点1之后会不断重试

直到找到节点1，高可用重新生成

如果有什么错误或者纰漏，恳请指正，谢谢