解密Spring Cloud微服务调用：如何轻松获取请求目标方的IP和端口

公众号「架构成长指南」，专注于生产实践、云原生、分布式系统、大数据技术分享。

目的

Spring Cloud 线上微服务实例都是2个起步，如果出问题后，在没有ELK等日志分析平台，如何确定调用到了目标服务的那个实例，以此来排查问题

效果

可以看到服务有几个实例是上线，并且最终调用了那个实例

考虑到Spring Cloud在版本升级中使用了两种负载均衡实现，Robin和LoadBalancer，下面我们提供两种实现方案

Robin实现方案

1. 技术栈

Spring Cloud: Hoxton.SR6
Spring Boot: 2.3.1.RELEASE
Spring-Cloud-Openfeign: 2.2.3.RELEASE

2. 继承RoundRobinRule，并重写`choose`方法

/*** 因为调用目标机器的时候，如果目标机器本身假死或者调用目标不通无法数据返回，那么feign无法打印目标机器。这种场景下我们需要在调用失败（目标机器没有返回）的时候也能把目标机器的ip打印出来，这种场景需要我们切入feign选择机器的逻辑，注入我们自己的调度策略（默认是roundrobin），在里面打印选择的机器即可。
*/
@Slf4j
public class FeignRule extends RoundRobinRule {@Overridepublic Server choose(Object key) {Server server = super.choose(key);if (Objects.isNull(server)) {log.info("server is null");return null;}log.info("feign rule ---> serverName:{}, choose key:{}, final server ip:{}", server.getMetaInfo().getAppName(), key, server.getHostPort());return server;}@Overridepublic Server choose(ILoadBalancer lb, Object key) {Server chooseServer = super.choose(lb, key);List<Server> reachableServers = lb.getReachableServers();List<Server> allServers = lb.getAllServers();int upCount = reachableServers.size();int serverCount = allServers.size();log.info("serverName:{} upCount:{}, serverCount:{}", Objects.nonNull(chooseServer) ? chooseServer.getMetaInfo().getAppName() : "", upCount, serverCount);for (Server server : allServers) {if (server instanceof DiscoveryEnabledServer) {DiscoveryEnabledServer dServer = (DiscoveryEnabledServer) server;InstanceInfo instanceInfo = dServer.getInstanceInfo();if (instanceInfo != null) {InstanceInfo.InstanceStatus status = instanceInfo.getStatus();if (status != null) {log.info("serverName:{} server:{}, status:{}", server.getMetaInfo().getAppName(), server.getHostPort(), status);}}}}return chooseServer;}
}

3.修改RibbonClients配置

import org.springframework.cloud.netflix.ribbon.RibbonClients;
import org.springframework.context.annotation.Configuration;
/*** @description:feign 配置*/
@Configuration
@RibbonClients(defaultConfiguration = {FeignRule.class})
public class FeignConfig {
}

LoadBalancer实现方案

1. 技术栈

Spring Cloud: 2021.0.4
Spring Boot: 2.7.17
Spring-Cloud-Openfeign: 3.1.4

2. 继承ReactorServiceInstanceLoadBalancer，并实现相关方法

@Slf4j
public class CustomRoundRobinLoadBalancer implements ReactorServiceInstanceLoadBalancer {final AtomicInteger position;final String serviceId;ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;public CustomRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId) {this(serviceInstanceListSupplierProvider, serviceId, (new Random()).nextInt(1000));}public CustomRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId, int seedPosition) {this.serviceId = serviceId;this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;this.position = new AtomicInteger(seedPosition);}public Mono<Response<ServiceInstance>> choose(Request request) {ServiceInstanceListSupplier supplier = this.serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);return supplier.get(request).next().map((serviceInstances) -> {return this.processInstanceResponse(supplier, serviceInstances);});}private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier, List<ServiceInstance> serviceInstances) {Response<ServiceInstance> serviceInstanceResponse = this.getInstanceResponse(serviceInstances);if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {((SelectedInstanceCallback)supplier).selectedServiceInstance((ServiceInstance)serviceInstanceResponse.getServer());}return serviceInstanceResponse;}private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {if (instances.isEmpty()) {if (log.isWarnEnabled()) {log.warn("No servers available for service: " + this.serviceId);}return new EmptyResponse();} else {int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;ServiceInstance instance = instances.get(pos % instances.size());log.info("serverName:{} upCount:{}",instance.getServiceId(),instances.size());log.info("feign rule ---> serverName:{}, final server ip:{}:{}", instance.getServiceId(), instance.getHost(),instance.getPort());return new DefaultResponse(instance);}}
}

2.修改LoadBalancerClients配置

@Configuration
@LoadBalancerClients(defaultConfiguration = CustomLoadBalancerConfiguration.class)
public class CustomLoadBalancerConfig {
}@Configuration
class CustomLoadBalancerConfiguration {/*** 参考默认实现* @see org.springframework.cloud.loadbalancer.annotation.LoadBalancerClientConfiguration#reactorServiceInstanceLoadBalancer* @return*/@Beanpublic ReactorLoadBalancer<ServiceInstance> reactorServiceInstanceLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);return new CustomRoundRobinLoadBalancer(loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);}
}