SpringCloud微服务实战-Eureka高可用

ゝ一纸荒年。 2022-02-28 01:48 311阅读 0赞

## 一、 Eureka Server： ##

### 1、项目结构：（pom.xml 附文章末尾） ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70][]

** Eureka 主配置类：EurekaApplication **

package com.lucifer.eureka;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
    
    @SpringBootApplication
    @EnableEurekaServer
    public class EurekaApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(EurekaApplication.class, args);
        }
    
    }

** ps:**

**Eureka Server的主配置类需要添加 @EnableEurekaServer注解；**

** Eureka 配置文件：application.yml**

#服务名称
    spring:
      application:
        name: eureka
    
    #eureka配置
    eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/
        register-with-eureka: false #是否向服务注册中心注册自己，默认是true，改成false，则在服务实例中看不到该服务
      server:
        enable-self-preservation: false  #自我保护模式，生产环境必须打开，开发环境可关闭
    #服务端口
    server:
     port: 8761

## 二、 Eureka Client： ##

### 1、项目结构：（pom.xml 附文章末尾） ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 1][]

**Eureka 配置文件：EurekaApplication .yml**

#eureka配置
    eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/
      #instance:
       # hostname: clientname
    
    #服务名
    spring:
      application:
        name: client

** ps:**

**Eureka Client****的主配置类需要添加 @EnableDiscoveryClient注解；**

package com.lucifer.client;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    
    @SpringBootApplication
    @EnableDiscoveryClient
    public class ClientApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(ClientApplication.class, args);
        }
    
    }

以上就是简单的Eureka Server和Client，实现了简单的注册和发现功能，但是想要实现高可用的话，就看以下部分；

本文就介绍3台Eureka Server：

![20190324000735862.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 2][]

**将EurekaApplication复制两份，为做区分，并命名为EurekaApplication（1），EurekaApplication（2），EurekaApplication（3），添加VM参数，分别-Dserver.port=8761，-Dserver.port=8762，-Dserver.port=8763；**

### **ps:** ###

**相当于有三台Eureka Server-------------------------------------->**

**Eureka Server 1（8761）：需要往Eureka Server 2（8762）、Eureka Server 3（8763）上注册**

**Eureka Server 2（8762）：需要往Eureka Server 1（8762）、Eureka Server 3（8763）上注册**

**Eureka Server 3（8763）：需要往Eureka Server 1（8762）、Eureka Server 2（8763）上注册**

**将Eureka Client的配置文件部分需要修改的内容做如下修改，将Client注册到三台Eureka Server中；其它部分不做修改；**

#eureka配置
    eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/,http://localhost:8763/eureka/

**Eureka Server 需要修改的部分：**

** 修改配置文件：(其它地方不变)**

**EurekaApplication(1) :**

#eureka配置
    eureka:
      client:
        service-url:
          defaultZone: http://localhost:8762/eureka/,http://localhost:8763/eureka/
    #服务端口
    #server:
     #port: 8761

修改完毕后，启动**EurekaApplication(1)服务：**

![20190324002635427.png][]

查看[http://localhost:8761/][http_localhost_8761]，可以看到client已经注册进来了；

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 3][]

**EurekaApplication(2) :**

切换到**EurekaApplication(2)** ，然后直接修改application.yml中，改成如图所示即可，启动**urekaApplication(2)；**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 4][]

查看[http://localhost:8762/][http_localhost_8761]，可以看到client已经注册进来了；

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 5][]

**EurekaApplication(3) :**

切换到**EurekaApplication(3)** ，然后直接修改application.yml中，改成如图所示即可，启动**urekaApplication(3)；**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 6][]

查看[http://localhost:8763/][http_localhost_8761]，可以看到client已经注册进来了；

![20190324003323560.png][]

### **注：** ###

此时关闭**EurekaApplication服务，**假设**EurekaApplication(1) 挂掉了，**[http://localhost:8761/][http_localhost_8761]这个地址现在无法访问了；

![20190324004330956.png][]

但是并不影响服务的注册和发现，因为另外两台**Eureka Server**依然启动着： [http://localhost:8762/][http_localhost_8762]，[http://localhost:8763/][http_localhost_8763]；

因此建议，**Eureka Server最少两台以上。**

**Eureka Server 的pmo.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">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.3.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>com.lucifer</groupId>
        <artifactId>eureka</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>eureka</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
            <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

**Eureka Client的pmo.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">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.3.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>com.lucifer</groupId>
        <artifactId>client</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>client</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
            <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
        </dependencies>
    
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

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[20190324000735862.png]: /images/20220228/87c10ce2ca404a1387299e716f6be26d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 2]: /images/20220228/597dbfb687154e178594794b13656af9.png
[20190324002635427.png]: /images/20220228/77f3985dcdd242459ee823d0ff9a6845.png
[http_localhost_8761]: http://localhost:8761/
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[20190324003323560.png]: /images/20220228/597c67d468d3463188ceda7d15387494.png
[20190324004330956.png]: /images/20220228/9e020eb1c2014f05bb6a69063ba33def.png
[http_localhost_8762]: http://localhost:8762/
[http_localhost_8763]: http://localhost:8763/