SpringCloud教程第7篇:高可用的分布式配置中心

上一篇文章讲述了一个服务如何从配置中心读取文件,配置中心如何从远程git读取配置文件,当服务实例很多时,都从配置中心读取文件,这时可以考虑将配置中心做成一个微服务,将其集群化,从而达到高可用,架构图如下:

Azure (3).png

一、准备工作

继续使用上一篇文章的工程,创建一个eureka-server工程,用作服务注册中心。

在其pom.xml文件引入Eureka的起步依赖spring-cloud-starter-eureka-server,代码如下:

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<?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>

<groupId>com.forezp</groupId>
<artifactId>eureka-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>eureka-server</name>
<description>Demo project for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<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-web</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>Dalston.RC1</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>

<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>


</project>

在配置文件application.yml上,指定服务端口为8889,加上作为服务注册中心的基本配置,代码如下:

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server:
port: 8889

eureka:
instance:
hostname: localhost
client:
registerWithEureka: false
fetchRegistry: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

入口类:

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@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {

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

二、改造config-server

在其pom.xml文件加上EurekaClient的起步依赖spring-cloud-starter-eureka,代码如下:

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<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-config-server</artifactId>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>

<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
</dependencies>

配置文件application.yml,指定服务注册地址为http://localhost:8889/eureka/,其他配置同上一篇文章,完整的配置如下:

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spring.application.name=config-server
server.port=8888

spring.cloud.config.server.git.uri=https://github.com/forezp/SpringcloudConfig/
spring.cloud.config.server.git.searchPaths=respo
spring.cloud.config.label=master
spring.cloud.config.server.git.username= your username
spring.cloud.config.server.git.password= your password
eureka.client.serviceUrl.defaultZone=http://localhost:8889/eureka/

最后需要在程序的启动类Application加上@EnableEureka的注解。

三、改造config-client

将其注册微到服务注册中心,作为Eureka客户端,需要pom文件加上起步依赖spring-cloud-starter-eureka,代码如下:

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<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>

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

<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>

配置文件bootstrap.properties,注意是bootstrap。加上服务注册地址为http://localhost:8889/eureka/

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spring.application.name=config-client
spring.cloud.config.label=master
spring.cloud.config.profile=dev
#spring.cloud.config.uri= http://localhost:8888/

eureka.client.serviceUrl.defaultZone=http://localhost:8889/eureka/
spring.cloud.config.discovery.enabled=true
spring.cloud.config.discovery.serviceId=config-server
server.port=8881


  • spring.cloud.config.discovery.enabled 是从配置中心读取文件。
  • spring.cloud.config.discovery.serviceId 配置中心的servieId,即服务名。

这时发现,在读取配置文件不再写ip地址,而是服务名,这时如果配置服务部署多份,通过负载均衡,从而高可用。

依次启动eureka-servr,config-server,config-client
访问网址:http://localhost:8889/

Paste_Image.png

访问http://localhost:8881/hi,浏览器显示:

foo version 3

本文源码下载:
https://github.com/forezp/SpringCloudLearning/tree/master/chapter7

四、参考资料

spring_cloud_config

请我吃🍗