簡介
eureka是Netflix開源的一個服務註冊與發現的組件,和其他Netflix的服務組件被整合爲Spring Cloud Netflix模塊。
和Consul,Zookeeper類似,eureka是一個用於服務註冊和發現的組件。
## eureka的基本架構
eureka主要包括下邊三種角色:
Register Service:服務註冊中心,是一個eureka server,提供服務註冊和發現的功能
Provider Service:服務提供者,是一個eureka client,提供服務
Consumer Service:服務消費者,也是eureka client,是去消費服務的
首先要有一個服務註冊中心eureka server,服務提供者要向服務註冊中心提供自己的服務名,ip地址,端口信息,通過REST API形式提交給服務註冊中心,同事服務消費者獲取一份服務註冊的列表,獲取服務信息,然後就可以通過http遠程調度來消費服務。
## 創建Eureka Server
先用maven創建父子工程的方式創建,在創建完maven工程後在主maven的pom文件下引入eureka-client和eureka-server
pom:
<?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.yt</groupId>
<artifactId>cloud_test</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.0.RELEASE</version>
<relativePath/>
</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>Greenwich.SR3</spring-cloud.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
<version>2.1.3.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
<version>2.1.3.RELEASE</version>
</dependency>
</dependencies>
</dependencyManagement>
</project>
然後創建子module工程,添加上pom
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.yt</groupId>
<artifactId>cloud_test</artifactId>
<version>1.0-SNAPSHOT</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>eureka-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>eureka-server</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<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>
</project>
接下來打開module的配置文件,改爲yml格式文件添加配置,通過server.port設置端口爲8761,eureka.instance.prefer-ip-addres爲true提交ip信息,默認情況下eureka會向自己註冊
,所以配置eureka.client.fetch-registry爲false防止註冊自己
server:
port: 8761
eureka:
instance:
prefer-ip-address: true
hostname: localhost
client:
register-with-eureka: false
fetch-registry: false
serviceUrl:
defaultZone:
http://${eureka.instance.hostname}:${server.port}/eureka/
在工程的啓動類上添加@EnableEurekaServer註解,啓動eureka server服務的功能然後啓動服務,打開http://localhost:8761/頁面看到如下就成功啓動了
添加eureka client
建一個新的module起名叫 eureka client
添加pom依賴,作爲client必要的是spring-cloud-starter-netflix-eureka-client這個依賴和spring-boot-starter-web這個依賴。
後一個包是因爲爲了單獨試一下client這個功能時候我一開始沒添加只加了client的依賴,但服務起來後直接關閉了,我想可能是因爲雖然一開始他確實是註冊到了註冊中心,但是隨着註冊完成,主線程結束,jvm也就一起退出了,容器close時會觸發DiscoveryClient的shutdown方法,便會註銷已註冊的節點。
然後加上一個web依賴是爲了tomcat、在啓動時候會創建一個webservie,開啓了一個用戶線程(非守護線程),這樣主線程退出後JVM也不會退出。也就不會觸發註銷節點的動作。
pom:
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.yt</groupId>
<artifactId>cloud_test</artifactId>
<version>1.0-SNAPSHOT</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>eureka-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>eureka-client</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.6.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>2.1.0.RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
配置他的yml
eureka:
client:
service-url:
defaultZone: http://localhost:8761/eureka/
server:
port: 8763
spring:
application:
name: eureka-client
然後在啓動類上加上@EnableEurekaClient開啓eurekaclient的功能。啓動服務,這時刷新註冊頁面,client已經被註冊了