多节点高可用Eureka集群配置与部署

前言

上一节讲的是动态扩容Eureka服务，说实话，一般情况这种操作并不多，一般多用在，由于大量服务节点部署后给Eureka造成压力突然积增，而解决的办法。这节讲的是一次启动或部署，直接就是集群多节点的，多用于服务节点相对稳定的场景。还有笔者这里有实际部署和应用的经验分享给大家，就是，我目前25个服务都注册在一个单节点Eureka上了（无论生产还是测试环境下），测试周期接近一年，我发现Eureka可靠性和可用性还是很高的，没有出现一次注册中心挂了的情况。还有，我一下内容没有花里胡哨的套话和流程图，想必大家最想解决的就是如何快速的解决自己的问题，所以以下基本都是贴出的代码，关键地方我会文字说明。代码还是基于《重新定义》的思想。

正文

首先还是创建一个父module，pom配置如下：

<groupId>cn.springcloud.book</groupId>
	<artifactId>ch3-2</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>pom</packaging>

	<name>ch3-2</name>
	<description>ch3-2</description>

	<modules>
		<module>ch3-2-zuul-gateway</module>
		<module>ch3-2-eureka-server</module>
		<module>ch3-2-eureka-client</module>
	</modules>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.3.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>
		<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
	</properties>

	<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>

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

然后创建EurekaServer服务，分别贴出pom文件和启动类

<groupId>cn.springcloud.book</groupId>
    <artifactId>ch3-2-eureka-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>ch3-2-eureka-server</name>
    <description>ch3-2-eureka-server</description>

    <parent>
        <groupId>cn.springcloud.book</groupId>
        <artifactId>ch3-2</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../pom.xml</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-netflix-eureka-server</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

@SpringBootApplication
@EnableEurekaServer
public class Ch322EurekaServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(Ch322EurekaServerApplication.class, args);
    }
}

 然后下面的内容是多节点配置的重要部分了

我会从上到下依次贴出这个目录的代码

eureka:
  server:
    use-read-only-response-cache: false
    response-cache-auto-expiration-in-seconds: 10
management:
  endpoints:
    web:
      exposure:
        include: '*'

server:
  port: 8761
spring:
  application:
    name: eureka-server
eureka:
  instance:
    hostname: localhost
    preferIpAddress: true
    metadataMap.zone: zone1
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      zone2: http://localhost:8763/eureka/,http://localhost:8764/eureka/
    availability-zones:
      region-east: zone1,zone2
  server:
      waitTimeInMsWhenSyncEmpty: 0
      enableSelfPreservation: false

server:
  port: 8762
spring:
  application:
    name: eureka-server
eureka:
  instance:
    hostname: localhost
    preferIpAddress: true
    metadataMap.zone: zone1
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      zone2: http://localhost:8763/eureka/,http://localhost:8764/eureka/
    availability-zones:
      region-east: zone1,zone2
  server:
      waitTimeInMsWhenSyncEmpty: 0
      enableSelfPreservation: false

server:
  port: 8763
spring:
  application:
    name: eureka-server
eureka:
  instance:
    hostname: localhost
    preferIpAddress: true
    metadataMap.zone: zone2
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      zone2: http://localhost:8763/eureka/,http://localhost:8764/eureka/
    availability-zones:
      region-east: zone1,zone2
  server:
      waitTimeInMsWhenSyncEmpty: 0
      enableSelfPreservation: false

server:
  port: 8764
spring:
  application:
    name: eureka-server
eureka:
  instance:
    hostname: localhost
    preferIpAddress: true
    metadataMap.zone: zone2
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      zone2: http://localhost:8763/eureka/,http://localhost:8764/eureka/
    availability-zones:
      region-east: zone1,zone2
  server:
      waitTimeInMsWhenSyncEmpty: 0
      enableSelfPreservation: false

 这里值得解释的是

上面我配置的是四个节点，分别在一个区域里，用region: region-east 配置，然后这个区域有两个空间分别是zone1和zone2

availability-zones:
  region-east: zone1,zone2
 这个配置代表了

然后8761和8762在zone1空间里，8763和8764在zone2空间里，请大家仔细看我上面的配置，按照配置理解用意。

还有必要解释的是WaitTimeInMsWhenSyncEmpty(*)：

这个设置为0是为了尽快让eureka server启动起来就提供rest api服务。默认是5分钟，也就是如果peer节点注册列表为空，那就等5分钟让其他服务有注册上来了，然后同步过来，再对外提供rest api服务。

UseReadOnlyResponseCache（*）：

目前采用的是二级缓存策略，一个是读写高速缓存过期策略，另一个没有过期只有只读缓存，默认为true，表示只读缓存。

然后进入eureka-server目录下分别执行

mvn spring-boot:run -Dspring.profiles.active=zone1a

mvn spring-boot:run -Dspring.profiles.active=zone1b

mvn spring-boot:run -Dspring.profiles.active=zone2a

mvn spring-boot:run -Dspring.profiles.active=zone1b

切记每次执行下一条命令需要再打开一个Terminal

这里笔者全部启动成功了。其实这时候你们访问http://localhost:8761/ 任意节点都是可以看到的。

但是我为了更好说明问题，这里加入一个eureka-client，并且这个客户端是双节点的，分别在zone1和zone2各一个

下面是client的pom和启动类

<groupId>cn.springcloud.book</groupId>
    <artifactId>ch3-2-eureka-client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>ch3-2-eureka-client</name>
    <description>ch3-2-eureka-client</description>

    <parent>
        <groupId>cn.springcloud.book</groupId>
        <artifactId>ch3-2</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../pom.xml</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-netflix-eureka-client</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

@SpringBootApplication
@EnableDiscoveryClient
public class Ch32EurekaClientApplication {

	public static void main(String[] args) {
		SpringApplication.run(Ch32EurekaClientApplication.class, args);
	}
}

下面我同样分别列出client的配置文件

management:
  endpoints:
    web:
      exposure:
        include: '*'

server:
  port: 8081
spring:
  application:
    name: client
eureka:
  instance:
    metadataMap.zone: zone1
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      zone2: http://localhost:8763/eureka/,http://localhost:8764/eureka/
    availability-zones:
      region-east: zone1,zone2

server:
  port: 8082
spring:
  application:
    name: client
eureka:
  instance:
    metadataMap.zone: zone2
  client:
    register-with-eureka: true
    fetch-registry: true
    region: region-east
    service-url:
      zone1: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      zone2: http://localhost:8763/eureka/,http://localhost:8764/eureka/
    availability-zones:
      region-east: zone1,zone2

 下面分别用命令启动两个节点，操作也是和eurekaServer是一样的，进入到client目录

分别使用mvn spring-boot:run -Dspring.profiles.active=zone1 和mvn spring-boot:run -Dspring.profiles.active=zone2

访问http://localhost:8761/

大家可以四个节点都访问以下，展示的页面和这一个是一样的。

好了，到这里已经讲解完多节点配置和应用了，

下面如果把这两个工程打成jar在服务器上分别启动不同配置文件jar的时候 

用java -Dspring.profiles.active=prod -jar xxx.jar 命令

注：对本文有异议或不明白的地方微信探讨，wx：15524579896