1、简介

https://github.com/Netflix/eureka/wiki

Eureka是Netflix开发的服务发现框架，本身是一个基于REST的服务。SpringCloud将它集成在其子项目spring-cloud-netflix中，以实现SpringCloud的服务注册和发现功能。 Eureka包含两个组件：Eureka Server和Eureka Client。

2、server 相关配置

2.1 pom.xml 文件

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.     <modelVersion>4.0.0</modelVersion>
  5.     <parent>
  6.         <groupId>org.springframework.boot</groupId>
  7.         <artifactId>spring-boot-starter-parent</artifactId>
  8.         <version>2.3.5.RELEASE</version>
  9.         <relativePath/> <!-- lookup parent from repository -->
  10.     </parent>
  11.     <groupId>com.morrow</groupId>
  12.     <artifactId>springcloud-eureka-6101</artifactId>
  13.     <version>0.0.1-SNAPSHOT</version>
  14.     <name>springcloud-eureka-6101</name>
  15.     <description>springcloud-eureka-6101 project for Spring Boot</description>
  16.     <properties>
  17.         <java.version>11</java.version>
  18.         <spring-cloud.version>Hoxton.SR6</spring-cloud.version>
  19.     </properties>
  20.     <dependencies>
  22.         <dependency>
  23.             <groupId>org.springframework.boot</groupId>
  24.             <artifactId>spring-boot-starter-web</artifactId>
  25.         </dependency>
  27.        <!--引入 eureka server-->
  28.         <dependency>
  29.             <groupId>org.springframework.cloud</groupId>
  30.             <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
  31.         </dependency>
  34.     </dependencies>
  36.     <!--全局管理springcloud版本,并不会引入具体依赖-->
  37.     <dependencyManagement>
  38.         <dependencies>
  39.             <dependency>
  40.                 <groupId>org.springframework.cloud</groupId>
  41.                 <artifactId>spring-cloud-dependencies</artifactId>
  42.                 <version>${spring-cloud.version}</version>
  43.                 <type>pom</type>
  44.                 <scope>import</scope>
  45.             </dependency>
  46.         </dependencies>
  47.     </dependencyManagement>
  49.     <build>
  50.         <plugins>
  51.             <plugin>
  52.                 <groupId>org.springframework.boot</groupId>
  53.                 <artifactId>spring-boot-maven-plugin</artifactId>
  54.             </plugin>
  55.         </plugins>
  56.     </build>
  58. </project>

2.2 yaml文件配置

  1. server:
  2.   port: 6101
  5. eureka:
  6.   client:
  7.     service-url:
  8.       defaultZone: http://localhost:6101/eureka  #指定服务注册中心的地址
  9.     fetch-registry: false                        #关闭作为客户端时从eureka server获取服务信息
  10.     register-with-eureka: false                  #不再将自己同时作为客户端进行注册
  12. spring:
  13.   application:
  14.     name: eureka-server

2.3 开启@EnableEurekaServer注解

  1. @SpringBootApplication
  2. @EnableEurekaServer
  3. public class SpringcloudEureka6101Application {
  5.     public static void main(String[] args) {
  6.         SpringApplication.run(SpringcloudEureka6101Application.class, args);
  7.     }
  9. }

2.4 访问地址

http://localhost:6101/

3、client 相关配置

3.1 pom.xml 文件

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.     <modelVersion>4.0.0</modelVersion>
  5.     <parent>
  6.         <groupId>org.springframework.boot</groupId>
  7.         <artifactId>spring-boot-starter-parent</artifactId>
  8.         <version>2.3.5.RELEASE</version>
  9.         <relativePath/> <!-- lookup parent from repository -->
  10.     </parent>
  11.     <groupId>com.morrow</groupId>
  12.     <artifactId>springcloud-eureka-client-6102</artifactId>
  13.     <version>0.0.1-SNAPSHOT</version>
  14.     <name>springcloud-eureka-client-6102</name>
  15.     <description>springcloud-eureka-client-6102 project for Spring Boot</description>
  16.     <properties>
  17.         <java.version>11</java.version>
  18.         <spring-cloud.version>Hoxton.SR6</spring-cloud.version>
  19.     </properties>
  20.     <dependencies>
  21.         <dependency>
  22.             <groupId>org.springframework.boot</groupId>
  23.             <artifactId>spring-boot-starter-web</artifactId>
  24.         </dependency>
  26.         <dependency>
  27.             <groupId>org.springframework.boot</groupId>
  28.             <artifactId>spring-boot-starter-test</artifactId>
  29.             <scope>test</scope>
  30.         </dependency>
  32.         <!--引入 eureka server-->
  33.         <dependency>
  34.             <groupId>org.springframework.cloud</groupId>
  35.             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
  36.         </dependency>
  39.     </dependencies>
  42.     <!--全局管理springcloud版本,并不会引入具体依赖-->
  43.     <dependencyManagement>
  44.         <dependencies>
  45.             <dependency>
  46.                 <groupId>org.springframework.cloud</groupId>
  47.                 <artifactId>spring-cloud-dependencies</artifactId>
  48.                 <version>${spring-cloud.version}</version>
  49.                 <type>pom</type>
  50.                 <scope>import</scope>
  51.             </dependency>
  52.         </dependencies>
  53.     </dependencyManagement>
  55.     <build>
  56.         <plugins>
  57.             <plugin>
  58.                 <groupId>org.springframework.boot</groupId>
  59.                 <artifactId>spring-boot-maven-plugin</artifactId>
  60.             </plugin>
  61.         </plugins>
  62.     </build>
  64. </project>

3.2 yaml文件配置

  1. server:
  2.   port: 6102
  5. eureka:
  6.   client:
  7.     service-url:
  8.       defaultZone: http://localhost:6101/eureka  #指定服务注册中心的地址
  10. spring:
  11.   application:
  12.     name: eureka-client

3.3 开启@EnableEurekaServer注解

  2. @SpringBootApplication
  3. @EnableEurekaClient
  4. public class SpringcloudEurekaClient6102Application {
  6.     public static void main(String[] args) {
  7.         SpringApplication.run(SpringcloudEurekaClient6102Application.class, args);
  8.     }
  10. }

image.png

自我保护机制

  • 官网地址: https://github.com/Netflix/eureka/wiki/Server-Self-Preservation-Mode
  • 默认情况下，如果Eureka Server在一定时间内（默认90秒）没有接收到某个微服务实例的心跳，Eureka Server将会移除该实例。但是当网络分区故障发生时，微服务与Eureka Server之间无法正常通信，而微服务本身是正常运行的，此时不应该移除这个微服务，所以引入了自我保护机制。Eureka Server在运行期间会去统计心跳失败比例在 15 分钟之内是否低于 85%，如果低于 85%，Eureka Server 会将这些实例保护起来，让这些实例不会过期。这种设计的哲学原理就是”宁可信其有不可信其无!”。自我保护模式正是一种针对网络异常波动的安全保护措施，使用自我保护模式能使Eureka集群更加的健壮、稳定的运行。

官方并不建议在生产情况下关闭

4、Eureka 停止更新

image.png

5、示例代码

springcloud-eureka-server-6101 springcloud-eureka-client-6102