什么是Ribbon
Ribbon is a client side load balancer which gives you a lot of control over the behaviour of HTTP and TCP clients.
上述是官方文档对Ribbon的解释，意思是Ribbon是一个客户端负载均衡器，它可以有效的控制HTTP和TCP客户端的访问。上述一段话有个很关键的词“客户端负载均衡器”，我们常用的负载均衡模式就是nginx反向代理模式,这种模式我们是不知道服务究竟请求的是那台机器的。这种负载均衡模式是服务端负载均衡。
而客户端负载均衡就是在发起请求是有明确的目标，请求精确指向集群中的某台机器。
</br> Ribbon的负载均衡默认是依靠Eureka来实现的，Ribbon通过Eureka客户端定期拉取注册服务，通过客户端的轮训、随机等算法来实现负载均衡。
快速开始
这个案例依赖Eureka-Server,请准备好server服务。Eureka相关查看Spring-Cloud系列(一) Eureka
添加依赖
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.13.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>Dalston.SR5</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-eureka</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>
看上面的依赖有些同学可能会奇怪,为什么没有引入Ribbon依赖，只引入了Eureka客户端。下面我们来看一下Eureka客户端的依赖关系图就明白了。
Eureka客户端依赖
从上图中我们明显可以看出来,Eureka客户端的依赖是包含Ribbon依赖的。所以我们不需要添加依赖。
代码
初始化bean
/**
* @LoadBalanced Ribbon整合注解，Rebbon本身依赖在EurekClient中存在。所以不需要继续引入
* Ribbon是客户端负载均衡实现之一,具有轮训，随机等等多种算法。
* @return
*/
@Bean
@LoadBalanced
public RestTemplate restTemplate(){
return new RestTemplate();
}
使用方式
@RestController
public class RibbonControlller {
@Autowired
private RestTemplate restTemplate;
@GetMapping("/url")
public String postUser() {
return this.restTemplate.getForObject("http://eureka-client-one/url", String.class);
}
}
application配置
server:
</br> port: 8082
</br>spring:
</br> application:
</br> name: ribbon-one
</br>eureka:
</br> instance:
</br> prefer-ip-address: true
</br> instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}
</br> client:
</br> serviceUrl:
</br> defaultZone: http://user:Pass123456@localhost:8761/eureka
启动效果
启动效果
自定义RibbonClient
代码自定义
定义配置
@Configuration
public class RibbonConfiguration {
@Autowired
private IClientConfig config;
@Bean
public IRule ribbonRule(IClientConfig config){
return new RandomRule();
}
}
The FooConfiguration has to be @Configuration but take care that it is not in a @ComponentScan for the main application context, otherwise it will be shared by all the @RibbonClients. If you use @ComponentScan (or @SpringBootApplication) you need to take steps to avoid it being included (for instance put it in a separate, non-overlapping package, or specify the packages to scan explicitly in the @ComponentScan).
注意Configuration类不能和主类平级，也不能在主类的子包下,否则该配置会覆盖本项目下所有的Ribben配置
代码配置
配置注入
@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name = "eureka-client-one",configuration = RibbonConfiguration.class)
public class RibbonApplication {
public static void main(String[] args) {
SpringApplication.run(RibbonApplication.class, args);
}
}
使用方式
@Autowired
private LoadBalancerClient loadBalancerClient;
@GetMapping("/test")
public String test() {
ServiceInstance instance = this.loadBalancerClient.choose("eureka-client-one");
return instance.toString();
}
可被重写的其他配置
上面的代码配置我们改变了IRule配置，更多例子参考官方文档。以下配置可以通过代码修改：
- IClientConfig ribbonClientConfig: DefaultClientConfigImpl
- IRule ribbonRule: ZoneAvoidanceRule
- IPing ribbonPing: NoOpPing
- ServerList<Server> ribbonServerList: ConfigurationBasedServerList
- ServerListFilter<Server> ribbonServerListFilter: ZonePreferenceServerListFilter
- ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
- ServerListUpdater ribbonServerListUpdater: PollingServerListUpdater
配置文件自定义
配置文件
users:#即需要调用的应用名
</br> ribbon:
</br> NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule
使用方式
@Autowired
private LoadBalancerClient loadBalancerClient;
@GetMapping("/test")
public String test() {
ServiceInstance instance = this.loadBalancerClient.choose("eureka-client-one");
return instance.toString();
}
注意！
</br>Ribbon的配置优先级顺序是 yml>javaConfig>default
其他配置选项
上面的配置文件我们改变IRule配置，更多例子参考官方文档。以下配置可以通过配置文件修改
- NFLoadBalancerClassName: should implement ILoadBalancer
- NFLoadBalancerRuleClassName: should implement IRule
- NFLoadBalancerPingClassName: should implement IPing
- NIWSServerListClassName: should implement ServerList
- NIWSServerListFilterClassName should implement ServerListFilter
Ribbon的其他配置
Ribbon禁用Eureka
ribbon:
</br> eureka:
</br> enabled: false
</br>users:#即需要调用的应用名
</br> ribbon:
</br> listOfServers: localhost:8080,localhost:8081 #服务IP List
延迟加载Ribbon
ribbon:
</br> eager-load:
</br> enabled: true
</br> clients: client1, client2, client3
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