搭建高可用的Eureka注册中心

一、搭建高可用的Eureka的作用

　　当服务器因种种原因导致Eureka注册中心(后面简称Eureka)服务当机(服务器跪了，异常关闭停止服务)。这样就会影响到整个业务的流程，因为你把所有的业务都注册到了Eureka中，当Eureka所依赖的docker(容器)当机了，这就会影响到所有在Eureka中注册的服务全部error。因为Eureka的请求流程在上一篇中说过，当A服务向B服务发送一个请求的时候，他是不会直接请求B服务，首先A服务先会到Eureka，Eureka拿到A服务请求的api，Eureka会通过这个api会去找在Eureka中注册的所有服务(这个过程叫做服务发现)，找到服务之后，Eureka会返回给A一个服务列表(因为B服务可能会做负载均衡，就是会向Eureka注册两个B服务，这个过程叫做服务消费)，当A服务拿到Eureka返回来的服务列表，根据自身的一些机制比如feign，ribbon等(这个后面都会讲到)进行处理。

二、第一个Eureka搭建

pom.xml文件的配置

 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">

 4     <modelVersion>4.0.0</modelVersion>

 5

 6     <groupId>cn.ds</groupId>

 7     <artifactId>eureka-server-001</artifactId>

 8     <version>0.0.1-SNAPSHOT</version>

 9     <packaging>jar</packaging>

10

11     <name>eureka-server-001</name>

12     <description>Eureka服务-001</description>

13

14     <parent>

15         <groupId>org.springframework.boot</groupId>

16         <artifactId>spring-boot-starter-parent</artifactId>

17         <version>2.0.3.RELEASE</version>

18         <relativePath/> <!-- lookup parent from repository -->

19     </parent>

20

21     <properties>

22         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

23         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

24         <java.version>1.8</java.version>

25         <spring-cloud.version>Finchley.RELEASE</spring-cloud.version>

26     </properties>

27

28     <dependencies>

29         <dependency>

30             <groupId>org.springframework.boot</groupId>

31             <artifactId>spring-boot-starter-web</artifactId>

32         </dependency>

33         <!-- 引入Eureka服务 -->

34         <dependency>

35             <groupId>org.springframework.cloud</groupId>

36             <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>

37         </dependency>

38         <dependency>

39             <groupId>org.springframework.boot</groupId>

40             <artifactId>spring-boot-devtools</artifactId>

41             <scope>runtime</scope>

42         </dependency>

43         <dependency>

44             <groupId>org.springframework.boot</groupId>

45             <artifactId>spring-boot-starter-test</artifactId>

46             <scope>test</scope>

47         </dependency>

48     </dependencies>

49

50     <dependencyManagement>

51         <dependencies>

52             <dependency>

53                 <groupId>org.springframework.cloud</groupId>

54                 <artifactId>spring-cloud-dependencies</artifactId>

55                 <version>${spring-cloud.version}</version>

56                 <type>pom</type>

57                 <scope>import</scope>

58             </dependency>

59         </dependencies>

60     </dependencyManagement>

61

62     <build>

63         <plugins>

64             <plugin>

65                 <groupId>org.springframework.boot</groupId>

66                 <artifactId>spring-boot-maven-plugin</artifactId>

67             </plugin>

68         </plugins>

69     </build>

70

71

72 </project>

application.properties配置：这里需要注意的是，IP地址不能写localhost或者127.0.0.1，后面会说到这个IP地址该怎么配置

 1 #    Eureka注册中心配置

 2     #    server-port：项目端口号

 3     #    spring-application-name：项目注册到Eureka显示的调用名称，类似于域名

 4     #    eureka.client.register-with-erueka：是否将自己注册到Eureka，默认为true

 5     #    eureka.client.fetch-registry：是否向Eureka获取注册信息，默认为true

 6     #    spring.jmx.default-domain：区分spring-boot项目

 7     #    eureka.instance.hostname：作为eureka-server-001服务配置中心

 8     #    eureka.client.service-url.defaultZone：双节点注册

 9 server.port = 8080

10 spring.application.name = eureka-server

11 eureka.client.register-with-eureka = true

12 eureka.client.fetch-registry = true

13 spring.jmx.default-domain = erueka-server-001

14 eureka.instance.hostname = eureka-server-001

15 eureka.client.service-url.defaultZone = http://eureka-server-001:8080/eureka/,http://eureka-server-002:8081/eureka/

springboot启动类配置

 1 package cn.yuzhenzi;

 2

 3 import org.springframework.boot.SpringApplication;

 4 import org.springframework.boot.autoconfigure.SpringBootApplication;

 5 import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

 6

 7 /**

 8  * @author    玉眞子

 9  * @name    springboot启动类

10  * */

11 @SpringBootApplication

12 @EnableEurekaServer            //启动注册中心

13 public class Application {

14

15     public static void main(String[] args) {

16         SpringApplication.run(Application.class, args);

17     }

18 }

三、第二个Eureka搭建

pom.xml文件的配置

 <?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>cn.ds</groupId>

     <artifactId>eureka-server-002</artifactId>

     <version>0.0.1-SNAPSHOT</version>

     <packaging>jar</packaging>

     <name>eureka-server-002</name>

     <description>Eureka服务-002</description>

     <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>

     <dependencies>

         <dependency>

             <groupId>org.springframework.boot</groupId>

             <artifactId>spring-boot-starter-web</artifactId>

         </dependency>

         <!-- 引入Eureka服务 -->

         <dependency>

             <groupId>org.springframework.cloud</groupId>

             <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>

         </dependency>

         <dependency>

             <groupId>org.springframework.boot</groupId>

             <artifactId>spring-boot-devtools</artifactId>

             <scope>runtime</scope>

         </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>

application.properties文件的配置：这里需要注意的是，IP地址不能写localhost或者127.0.0.1，后面会说到这个IP地址该怎么配置

 #    Eureka注册中心配置

     #    server-port：项目端口号

     #    spring-application-name：项目注册到Eureka显示的调用名称，类似于域名

     #    eureka.client.register-with-erueka：是否将自己注册到Eureka，默认为true

     #    eureka.client.fetch-registry：是否向Eureka获取注册信息，默认为true

     #    spring.jmx.default-domain：区分spring-boot项目

     #    eureka.instance.hostname：作为eureka-server-001服务配置中心

     #    eureka.client.service-url.defaultZone：双节点注册

 server.port = 8081

 spring.application.name = eureka-server

 eureka.client.register-with-eureka = true

 eureka.client.fetch-registry = true

 spring.jmx.default-domain = eureka-server-002

 eureka.instance.hostname = eureka-server-002

 eureka.client.service-url.defaultZone = http://eureka-server-002:8081/eureka/,http://eureka-server-001:8080/eureka/

springboot启动类的配置

 package cn.yuzhenzi;

 import org.springframework.boot.SpringApplication;

 import org.springframework.boot.autoconfigure.SpringBootApplication;

 import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

 /**

  * @author    玉眞子

  * @name    springboot启动类

  * */

 @SpringBootApplication

 @EnableEurekaServer                //启动注册中心

 public class Application {

     public static void main(String[] args) {

         SpringApplication.run(Application.class, args);

     }

 }

四、IP配置以及注意事项

IP配置

windows配置：/windows/system32/drivers/etc/hosts
Linux配置：/etc/hosts

如图所示：

 1 # Copyright (c) 1993-2009 Microsoft Corp.

 2 #

 3 # This is a sample HOSTS file used by Microsoft TCP/IP for Windows.

 4 #

 5 # This file contains the mappings of IP addresses to host names. Each

 6 # entry should be kept on an individual line. The IP address should

 7 # be placed in the first column followed by the corresponding host name.

 8 # The IP address and the host name should be separated by at least one

 9 # space.

10 #

11 # Additionally, comments (such as these) may be inserted on individual

12 # lines or following the machine name denoted by a '#' symbol.

13 #

14 # For example:

15 #

16 #      102.54.94.97     rhino.acme.com          # source server

17 #       38.25.63.10     x.acme.com              # x client host

18

19 # localhost name resolution is handled within DNS itself.

20 #    127.0.0.1       localhost

21 #    ::1             localhost

22 127.0.0.1    eureka-server-001

23 127.0.0.1    eureka-server-002

注意事项：当项目启动时会报错，这是正常现象，因为eureka-server-001要注册到eureka-server-002上面，但是eureka-server-002项目还没有启动起来，所以会报错

五、测试分别访问http://localhost:8080/eureka/和http://localhost:8081/eureka/