微服務學習——EuerkaServer搭建
阿新 • • 發佈：2018-11-07
現在微服務架構越來越普及，目前接觸到主要有dubbo和springcloud
在springcloud中使用euerkaserver作為服務的註冊和發現的中心
簡單搭建EuerkaServer
1 在eclipse新建一個maven專案，在pom.xml檔案中新增相關依賴
<!-- 新增eureka-server --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka-server</artifactId> </dependency> <!-- 新增springboot --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency>
<parent>
<!-- Your own application should inherit from spring-boot-starter-parent -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.4.RELEASE</version>
</parent>
完整的pom.xml
<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> <!-- Your own application should inherit from spring-boot-starter-parent --> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.4.RELEASE</version> </parent> <artifactId>EuerkaServer</artifactId> <groupId>com.wxf.SpringCloud</groupId> <name>Spring Boot Actuator Sample</name> <description>Spring Boot Actuator Sample</description> <version>0.0.1-SNAPSHOT</version> <url>http://projects.spring.io/spring-boot/</url> <organization> <name>Pivotal Software, Inc.</name> <url>http://www.spring.io</url> </organization> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <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</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-security</artifactId> </dependency> --> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>Dalston.SR1</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>
2 新增啟動類
在啟動類加入註解@EnableEurekaServer
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@EnableEurekaServer
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
3 修改application.properties內容
spring.application.name=com.wxf.SpringCloud.EuerkaServer.actuator.Application
server.port=1111
#強制不註冊到註冊伺服器
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
#註冊中心地址
eureka.client.serviceUrl.defaultZone=http://localhost:${server.port}/eureka/
#驅逐下線的服務，間隔,5秒，預設是60，建議開發和測試環境配置
#org.springframework.cloud.netflix.eureka.server.EurekaServerConfigBean.evictionIntervalTimerInMs
eureka.server.evictionIntervalTimerInMs=5000
4 登陸管理頁面
搭建生產者
pom.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>
<artifactId>SpringCloud.Client</artifactId>
<groupId>com.wxf.SpringCloud</groupId>
<name>Spring Boot Actuator Sample</name>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.4.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<!--埠監控依賴包-->
<!-- <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>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR1</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>
啟動類
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@EnableEurekaClient
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
application.properties
spring.application.name=Application-Provider
server.port=8181
#註冊中心地址
eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka/
management.endpoints.enabled-by-default=false
接下來我們進入euerka管理頁面
搭建消費者
pom.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>
<artifactId>SpringCloud.Client</artifactId>
<groupId>com.wxf.SpringCloud</groupId>
<name>Spring Boot Actuator Sample</name>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.4.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<!-- <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>
<!--服務呼叫-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR1</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>
啟動類
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;
@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
控制層
controller
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class controller {
@Autowired
Service serviceAFeignClient;
@RequestMapping(value = "/*",method = RequestMethod.GET)
@ResponseBody
public String getHello(){
String hi = serviceAFeignClient.hi();
if (hi.isEmpty()){
hi="遠端呼叫失敗";
}
else {
hi="收到遠端資訊"+hi;
}
return hi;
}
}
service
import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
@Component
@FeignClient(value = "Application-Provider") //這裡的name對應呼叫服務的spring.applicatoin.name
public interface Service {
@RequestMapping(value = "/hi")
String hi();
}
執行後在euerka註冊中心中可以到到服務
訪問消費者，成功呼叫了提供者暴露的介面
上述內容已經完成了簡單的服務註冊、發現與呼叫。
注意事項：
註解：
- @EnableEurekaServer
啟動服務註冊中心 - @EnableDiscoveryClient
註冊服務至註冊中心（不單是euerka） - @EnableEurekaClient
註冊服務至註冊中心（只能是euerka） - @EnableFeignClients
需要在啟動項上加上才可以呼叫FeignClient - @FeignClient(value = “Application-Provider”)
呼叫外部服務介面
依賴包：
<!-- euerka註冊中心-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<!-- 外部服務呼叫-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
疑問
服務是如何註冊和發現的？
點選這裡
Euerka Server
- 註冊：各個微服務啟動時，會通過Eureka Client向Eureka Server進行註冊自己的資訊（例如服務資訊和網路資訊），Eureka Server會儲存該服務的資訊。
- 呼叫：服務消費者在呼叫服務時，本地Eureka Client沒有的情況下，會到Eureka Server拉取資訊。
- 維護：
Cancel 服務下線–Eureka客戶端在程式關閉時向Eureka伺服器傳送取消請求
Eviction 服務剔除–當Eureka客戶端連續90秒沒有向Eureka伺服器傳送服務續約，即心跳，Eureka伺服器會將該服務例項從服務註冊列表刪除，即服務剔除。
renew 服務續約–Eureka Client會每隔30秒傳送一次心跳來續約。 通過續約來告知Eureka Server該Eureka客戶仍然存在，沒有出現問題。
服務資訊如何同步？
為保證服務的高可用，一般會部署多個EuerkaServer，防止其中某個註冊中心出現宕機影響服務的呼叫。
每個Eureka Server同時也是Eureka Client，多個Eureka Server之間通過P2P複製的方式完成服務登錄檔的同步。同步時，被同步資訊不會同步出去。也就是說有3個Eureka Server，Server1有新的服務資訊時，同步到Server2後，Server2和Server3同步時，Server2不會把從Server1那裡同步到的資訊同步給Server3，只能由Server1自己同步給Server3。