Spring Cloud使用ribbon实现负载均衡
Ribbon是什么？
Ribbon是Netflix发布的开源项目，主要功能是提供客户端的软件负载均衡算法，将Netflix的中间层服务连接在一起。Ribbon客户端组件提供一系列完善的配置项如连接超时，重试等。也可以使用Ribbon实现自定义的负载均衡算法。
Spring Cloud使用Ribbon实现负载均衡
Ribbon默认使用轮询来实现负载均衡，也就是如果我们将同一个服务部署在A和B机器上，那么第一次请求将到A，第二次请求将到B
1.创建Eureka Server
创建一个Spring Boot工程eureka-server
注意Spring Boot与Spring Cloud版本必须对应，否则会报错。
[查看版本信息]https://spring.io/projects/spring-cloud
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>4.0.0modelVersion>
<parent>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-parentartifactId>
<version>2.1.5.RELEASEversion>
<relativePath/>
parent>
<groupId>com.dfyanggroupId>
<artifactId>eureka-serverartifactId>
<version>0.0.1-SNAPSHOTversion>
<name>eureka-servername>
<description>Demo project for Spring Bootdescription>
<properties>
<java.version>1.8java.version>
properties>
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starterartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-netflix-eureka-serverartifactId>
dependency>
dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-dependenciesartifactId>
<version>Greenwich.RELEASEversion>
<type>pomtype>
<scope>importscope>
dependency>
dependencies>
dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-maven-pluginartifactId>
plugin>
plugins>
build>
project>
application.yml
server:
port: 8761
spring:
application:
name: eureka-server
eureka:
client:
# 是否将自己注册到Eureka Server，由于当前应用为Eureka Service，故为false
register-with-eureka: false
# 是否从Eureka Server获取注册信息，由于是单点，所以为false
fetch-registry: false
# 与Eureka Server交互的地址，默认是http://localhost:8761/eureka
service-url:
default-zone: http://localhost:8761/eureka/
在启动类上加上@EnableEurekaServer注解，表明是一个Eureka Server
package com.dfyang;
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);
}
}
启动项目，访问localhost:8761
2.创建第一个服务提供者service-producer
创建一个Spring Boot工程service-producer
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>4.0.0modelVersion>
<parent>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-parentartifactId>
<version>2.1.5.RELEASEversion>
<relativePath/>
parent>
<groupId>com.dfyanggroupId>
<artifactId>service-producerartifactId>
<version>0.0.1-SNAPSHOTversion>
<name>service-producername>
<description>Demo project for Spring Bootdescription>
<properties>
<java.version>1.8java.version>
properties>
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starterartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
dependency>
dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-dependenciesartifactId>
<version>Greenwich.RELEASEversion>
<type>pomtype>
<scope>importscope>
dependency>
dependencies>
dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-maven-pluginartifactId>
plugin>
plugins>
build>
project>
application.yml
server:
port: 8080
spring:
application:
name: service-producer
eureka:
client:
service-url:
default-zone: http://localhost:8761/eureka/
启动类上加上@EnableEurekaClient，表明是一个Eureka Client。
每个服务提供者也能作为服务消费者消费服务
package com.dfyang;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@SpringBootApplication
@EnableEurekaClient
public class ServiceProducerApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceProducerApplication.class, args);
}
}
编写接口
package com.dfyang.serviceProducer.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class ProducerController {
@RequestMapping("/service")
public String service() {
return "服务A";
}
}
启动服务，输入localhost:8761
3.创建第二个服务提供者service-producer1
创建另一个一个Spring Boot工程service-producer1
要修改的只有两个地方，端口号和接口(为了展示区别)
application.yml
server:
port: 8081
spring:
application:
name: service-producer
eureka:
client:
service-url:
default-zone: http://localhost:8761/eureka/
编写接口
package com.dfyang.serviceProducer.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class ProducerController {
@RequestMapping("/service")
public String service() {
return "服务B";
}
}
启动服务，输入localhost:8761
4.创建服务消费者service-consumer(eureka client)
创建一个Spring Boot工程service-consumer
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>4.0.0modelVersion>
<parent>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-parentartifactId>
<version>2.1.5.RELEASEversion>
<relativePath/>
parent>
<groupId>com.dfyanggroupId>
<artifactId>service-consumerartifactId>
<version>0.0.1-SNAPSHOTversion>
<name>service-consumername>
<description>Demo project for Spring Bootdescription>
<properties>
<java.version>1.8java.version>
properties>
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starterartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
dependency>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-netflix-ribbonartifactId>
dependency>
dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-dependenciesartifactId>
<version>Greenwich.RELEASEversion>
<type>pomtype>
<scope>importscope>
dependency>
dependencies>
dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-maven-pluginartifactId>
plugin>
plugins>
build>
project>
application.yml
server:
port: 8082
spring:
application:
name: service-consumer
eureka:
client:
service-url:
default-zone: http://localhost:8761/eureka/
在启动类似加上@EnableDiscoveryClient（该注解与@EnableEurekaClient均表明是一个Eureka客户端，但@EnableEurekaClient只能在Eureka使用）
package com.dfyang;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
@EnableDiscoveryClient
public class ServiceConsumerApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceConsumerApplication.class, args);
}
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
消费者获取服务
package com.dfyang.serviceConsumer.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class ConsumerController {
@Autowired
private RestTemplate restTemplate;
@GetMapping("/consume")
public String consume() {
return restTemplate.getForObject("http://service-producer/service", String.class);
}
}
输入localhost:8761
输入http://localhost:8082/consume
我们会看到服务A与服务B在交替执行
使用Ribbon的其他负载均衡策略
随机
只需修改消费端程序入口
package com.dfyang;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
@EnableDiscoveryClient
public class ServiceConsumerApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceConsumerApplication.class, args);
}
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
@Bean
public IRule ribbonRule() {
return new RandomRule();
}
}
- BestAvailableRule
选择一个最小的并发请求的server - AvailabilityFilteringRule
过滤掉那些因为一直连接失败的被标记为circuit tripped的后端server，并过滤掉那些高并发的的后端server - WeightedResponseTimeRule
根据相应时间分配一个weight，相应时间越长，weight越小，被选中的可能性越低。 - RetryRule
对选定的负载均衡策略机上重试机制。 - RoundRobinRule
轮询调度 - RandomRule
随机选择一个server - ZoneAvoidanceRule
复合判断server所在区域的性能和server的可用性选择server