如何配置Spring负载均衡策略以使用当前流量最少的实例？

Question

我在 Spring 微服务项目中使用 Spring Cloud 负载均衡器作为客户端负载均衡器。我知道默认情况下 Spring 负载均衡器使用循环策略。但对于我的用例来说，

Least connections

策略是最适合的。处理最少连接数的实例将请求路由到它。在深入研究文档后，我发现

@LoadBalancerClient

注释可以让您了解路由算法。 所以，我这样做了：

@Configuration
@LoadBalancerClient(configuration = BalancerConfig.class)
public class RestConfig {
    @Bean
    @LoadBalanced
    RestTemplate restClient(RestTemplateBuilder builder) {
        return builder.build();
    }
}  

对于 BalancerConfig.java 类，我有：

@Configuration
public class BalancerConfig {
    @Bean
    ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,
            LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
         // currently selects an instance randomly of a given service.
        // but I want to switch it to use the instance that is currently having least 
       // traffic
        return new RandomLoadBalancer(loadBalancerClientFactory
                .getLazyProvider(name, ServiceInstanceListSupplier.class),
                name);
    }
}

请告诉我 Spring 应用程序网关是否可以实现？

Answer 1

如果您希望所有客户端都使用自定义策略，您只需要定义一个ReactorLoadBalancer bean，如下所示

@Bean
ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,
                                                        LoadBalancerClientFactory loadBalancerClientFactory) {
    String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
    return new RandomLoadBalancer(loadBalancerClientFactory
            .getLazyProvider(name, ServiceInstanceListSupplier.class),
            name);
}

但是如果你想为每个客户定制不同的策略，你需要这样做

public class RestConfig {
    @Bean
    ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,
                                                            LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
        return new RandomLoadBalancer(loadBalancerClientFactory
                .getLazyProvider(name, ServiceInstanceListSupplier.class),
                name);
    }
}

配置两条路由

spring.cloud.gateway.routes[0].id=web
spring.cloud.gateway.routes[0].uri=lb://web
spring.cloud.gateway.routes[0].predicates[0]=Path=/web/**
spring.cloud.gateway.routes[1].id=reactive-web
spring.cloud.gateway.routes[1].uri=lb://reactive-web
spring.cloud.gateway.routes[1].predicates[0]=Path=/reactive/**

运行 GateWay 应用程序

@LoadBalancerClient(value = "reactive-web",configuration = RestConfig .class)
@SpringBootApplication
public class GateWayApplication {

    public static void main(String[] args) {
        SpringApplication.run(GateWayApplication.class, args);
    }

}

这样第一条路由使用了RoundRobinLoadBalancer，第二条路由使用了RandomLoadBalancer。