Eureka + Ribbon實現微服務的服務發現和負載均衡
阿新 • • 發佈：2018-12-20
目錄
3：搭建Eureka Provider (服務提供者，即Eureka Client)
1:原理結構圖
2:搭建Eureka Server服務註冊中心
建立工程，引入Eureka，建立好的工程pom檔案如下：
<?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.eureka</groupId> <artifactId>EurekaServer</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>EurekaServer</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.1.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>Greenwich.M3</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-server</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>${spring-cloud.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> <repositories> <repository> <id>spring-milestones</id> <name>Spring Milestones</name> <url>https://repo.spring.io/milestone</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> </project>
在啟動類上加上 @EnableEurekaServer註解，啟動註冊服務中心，啟動類程式碼如下：
import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; @SpringBootApplication @EnableEurekaServer public class EurekaServerApplication { public static void main(String[] args) { SpringApplication.run(EurekaServerApplication.class, args); } }
配置application.yml檔案
server: port: 8081 #服務註冊中心埠號 eureka: instance: hostname: 127.0.0.1 #服務註冊中心IP地址 client: registerWithEureka: false #是否向服務註冊中心註冊自己 fetchRegistry: false #是否檢索服務 serviceUrl: #服務註冊中心的配置內容，指定服務註冊中心的位置 defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
打成jar包，執行該工程後，在瀏覽器上輸入http://127.0.0.1:8081，看到如下介面，目前該頁面暫無註冊的服務提供者和消費者
3：搭建Eureka Provider (服務提供者，即Eureka Client)
建立工程，引入eureka 和spring boot web，其pom檔案如下:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.eureka</groupId>
<artifactId>EurekaProvider</artifactId>
<version>0.0.1</version>
<packaging>jar</packaging>
<name>EurekaProvider</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.M3</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${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>
<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>
建立一個RestController訪問方法:
@Value("${server.port}")
private String port;
@GetMapping("/home")
public String homePage() {
return "Welcome to home page"+" : " + port;
}在啟動類上加上 @EnableEurekaClient註解，申明是Eureka客戶端
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@SpringBootApplication
@EnableEurekaClient
public class EurekaProviderApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaProviderApplication.class, args);
}
}配置application.yml檔案
eureka:
client:
serviceUrl: #註冊中心的註冊地址
defaultZone: http://127.0.0.1:8081/eureka/
server:
port: 8082 #服務埠號
spring:
application:
name: service-provider #服務名稱--呼叫的時候根據名稱來呼叫該服務的方法
打成jar，執行兩個例項
java -jar EurekaProvider-0.0.1.jar //配置檔案中設定成8082埠
java -jar EurekaProvider-0.0.1.jar --server.port=8083
成功執行後，Eureka服務註冊中心會註冊兩個provider例項，如下介面：
4：搭建 Eurka-Consumer
主要目的是用來消費服務，同時提供負載均衡的功能。引入Eurka,web後的pom檔案如下：
<?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.eureka</groupId>
<artifactId>EurekaConsumer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>EurekaConsumer</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.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>Greenwich.M3</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</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>${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>
<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>
在啟動類中往spring boot容器中新增RestTemplate物件和IRule物件(用於負載均衡)，後期會對常用的負載均衡策略方法做個總結。
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
@SpringBootApplication
@EnableEurekaClient
public class EurekaConsumerApplication {
@LoadBalanced
@Bean
public RestTemplate rest() {
return new RestTemplate();
}
@Bean
public IRule ribbonRule() {
return new RandomRule(); //隨機負載均衡策略,如未向容器中注入，預設是輪詢方式
}
public static void main(String[] args) {
SpringApplication.run(EurekaConsumerApplication.class, args);
}
}注意：在往容器中注入RestTemplate物件時，需要加上@LoadBalanced註解，否則不能正常訪問Eurka中的服務。其原理可以參考https://blog.csdn.net/jin5203344/article/details/80496078
新增Controller，提供給外部訪問的介面以及訪問provider提供的介面
@RestController
public class goHomePage {
@Autowired
private RestTemplate restTemplate;
@GetMapping("/home")
public String getHome() {
String data = restTemplate.getForObject("http://service-provider/home", String.class);
return data;
}
}配置application. yml
eureka:
client:
serviceUrl: #註冊中心的註冊地址
defaultZone: http://127.0.0.1:8081/eureka/
server:
port: 8093 #服務埠號
spring:
application:
name: service-consumer #服務名稱--呼叫的時候根據名稱來呼叫該服務的方法執行Consumer專案，在Eureka 註冊中心的管理頁面上可以看到其註冊資訊
目前為止，已經完成 Eureka的註冊中心，服務提供者，消費者。在瀏覽器中輸入http://127.0.0.1:8093/home 即可訪問到服務提供者提供的資料，如下截圖：
Eureka在開發除錯時會涉及到多個服務提供者，不適合點對點的調測，故後續會記錄點對點的直連方式，結構如下：
