05-SpringCloud 之 Eureka

什么是 Eureka

Eureka 即：服务发现框架，提供服务注册与发现功能，分为 Eureka Server 和 Eureka Client

Eureka Server：作为服务端，提供服务注册与订阅功能
Eureka Client：作为客户端，Provider 可以到 Eureka Server 中注册自己提供的服务，Consumer 可以从 Eureka Server 中订阅自己所需要的服务

Eureka Server 配置

新建 Module：spring-cloud-eureka-server-7001

编写 pom 引入依赖

pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>spring-cloud-netflix</artifactId>
        <groupId>com.kaishen</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>spring-cloud-eureka-server-7001</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <!-- 引入该模块所需依赖 -->
    <dependencies>
        <!-- Eureka Server -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
    </dependencies>
</project>

编写 application.yml

application.yml

server:
  port: 7001

# Eureka 配置
eureka:
  instance:
    hostname: eureka7001.com # 服务实例名
  client:
    register-with-eureka: false # 是否向注册中心注册
    fetch-registry: false # 自己就是注册中心
    service-url:
      defaultZone: http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/ # 此为集群配置，用逗号分隔，可只配一个，作为当个注册中心使用

编写启动类，开启注解

EurekaServerApplication7001

package com.kaishen;

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

/**
 * Eureka 服务启动类
 * @author : toby
 * Create in 17:46 2022/5/8
 */
@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication7001 {

    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApplication7001.class, args);
    }
}

Eureka Server 集群配置

主机设置，可以在 C:\Windows\System32\drivers\etc\hosts 中模拟不同主机，实现伪集群
同 Eureka Server 配置，创建 spring-cloud-eureka-server-7002/spring-cloud-eureka-server-7003
修改各自的 application.yml，将 eureka.client.service-url.defaultZone 属性配置为集群即可
启动集群，访问任意节点可以看到以下界面，即集群配置完成

Eureka Client 配置

新建 Module：spring-cloud-provider-dept-8001

编写 pom 引入依赖

pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>spring-cloud-netflix</artifactId>
        <groupId>com.kaishen</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>spring-cloud-provider-dept-8001</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <!-- 引入该模块所需依赖 -->
    <dependencies>
        <!-- api -->
        <dependency>
            <groupId>com.kaishen</groupId>
            <artifactId>spring-cloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <!-- junit -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- log4j -->
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
        </dependency>

        <!-- logback -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
        </dependency>

        <!-- lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!-- SpringBoot Web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- SpringBoot 监控 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <!-- DataSource -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>

        <!-- MySQL -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <!-- MyBatis -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>

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

编写 application.yml

application.yml

server:
  port: 8001

# Spring 配置
spring:
  application:
    name: spring-cloud-provider-dept
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource # 数据源
    driver-class-name: org.gjt.mm.mysql.Driver # 驱动
    url: jdbc:mysql://localhost:3306/db01?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
    username: root
    password: 123456

# MyBatis 配置
mybatis:
  mapper-locations: classpath:mybatis/mappings/*.xml
  type-aliases-package: com.kaishen.pojo

# 监控信息配置
info:
  app.name: kaishen-spring-cloud-dept8001

# Eureka 配置
eureka:
  client:
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/
  instance:
    instance-id: spring-cloud-provider-dept8001 # 服务描述信息
    prefer-ip-address: true # 显示 ip 地


####### Consumer 配置如下 #######
server:
  port: 80

# Eureka 配置
eureka:
  client:
    register-with-eureka: false # Consumer 无需注册
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

编写启动类，开启注解：

DeptProviderApplication8001

package com.kaishen;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;

/**
 * 部门服务启动类
 * @author : toby
 * Create in 18:50 2022/5/8
 */
@SpringBootApplication
@EnableEurekaClient
public class DeptProviderApplication8001 {

    public static void main(String[] args) {
        SpringApplication.run(DeptProviderApplication8001.class, args);
    }
}

启动服务后，可在 Eureka Server 界面看到如下信息，即已完成服务注册
之后便可继续完善微服务业务功能，新建 dao、mapper、service、controller 等

Eureka 自我保护机制

默认情况下，EurekaServer 在一定时间内 (默认 90s) 没有接收到微服务的心跳，EurekaServer 将会移除该微服务的实例
自我保护机制：如果在 15 分钟内超过 85% 的节点都没有了正常心跳，那么 Eureka 就会认为客户端与注册中心发生了网络故障，EurekaServer 将自动进入自我保护状态，此时会出现以下几种情况
- EurekaServer 不再从注册列表中移除因长时间没有收到心跳的服务
- EurekaServer 仍然能够接收新的服务注册与查询请求，但不会被同步到其他节点上 (即：保证当前节点仍然可用)
- 当网络稳定后，当前实例上新的注册信息会被同步到其他节点
关闭自我保护机制(不推荐)：eureka.server.enable-self-preservation = false

posted @ 2022-05-28 09:28 kaishen 阅读(26) 评论(0) 收藏举报

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