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 ...

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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

1. /**
2. * 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。
3. */
4. @Slf4j
5. public class FeignRule extends RoundRobinRule {
7.     @Override
8.     public Server choose(Object key) {
9.         Server server = super.choose(key);
10.         if (Objects.isNull(server)) {
11.             log.info("server is null");
12.             return null;
13.         }
14.         log.info("feign rule ---> serverName:{}, choose key:{}, final server ip:{}", server.getMetaInfo().getAppName(), key, server.getHostPort());
15.         return server;
16.     }
18.     @Override
19.     public Server choose(ILoadBalancer lb, Object key) {
20.         Server chooseServer = super.choose(lb, key);
22.         List<Server> reachableServers = lb.getReachableServers();
23.         List<Server> allServers = lb.getAllServers();
24.         int upCount = reachableServers.size();
25.         int serverCount = allServers.size();
26.         log.info("serverName:{} upCount:{}, serverCount:{}", Objects.nonNull(chooseServer) ? chooseServer.getMetaInfo().getAppName() : "", upCount, serverCount);
27.         for (Server server : allServers) {
28.             if (server instanceof DiscoveryEnabledServer) {
29.                 DiscoveryEnabledServer dServer = (DiscoveryEnabledServer) server;
30.                 InstanceInfo instanceInfo = dServer.getInstanceInfo();
31.                 if (instanceInfo != null) {
32.                     InstanceInfo.InstanceStatus status = instanceInfo.getStatus();
33.                     if (status != null) {
34.                         log.info("serverName:{} server:{}, status:{}", server.getMetaInfo().getAppName(), server.getHostPort(), status);
35.                     }
36.                 }
37.             }
38.         }
40.         return chooseServer;
41.     }
42. }

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3.修改RibbonClients配置

1. import org.springframework.cloud.netflix.ribbon.RibbonClients;
2. import org.springframework.context.annotation.Configuration;
3. /**
4. * @description:feign 配置
5. */
6. @Configuration
7. @RibbonClients(defaultConfiguration = {FeignRule.class})
8. public class FeignConfig {
9. }

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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

1. @Slf4j
2. public class CustomRoundRobinLoadBalancer implements ReactorServiceInstanceLoadBalancer {
3.     final AtomicInteger position;
4.     final String serviceId;
5.     ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;
7.     public CustomRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId) {
8.         this(serviceInstanceListSupplierProvider, serviceId, (new Random()).nextInt(1000));
9.     }
11.     public CustomRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId, int seedPosition) {
12.         this.serviceId = serviceId;
13.         this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;
14.         this.position = new AtomicInteger(seedPosition);
15.     }
17.     public Mono<Response<ServiceInstance>> choose(Request request) {
18.         ServiceInstanceListSupplier supplier = this.serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);
19.         return supplier.get(request).next().map((serviceInstances) -> {
20.             return this.processInstanceResponse(supplier, serviceInstances);
21.         });
22.     }
24.     private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier, List<ServiceInstance> serviceInstances) {
25.         Response<ServiceInstance> serviceInstanceResponse = this.getInstanceResponse(serviceInstances);
26.         if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {
27.             ((SelectedInstanceCallback)supplier).selectedServiceInstance((ServiceInstance)serviceInstanceResponse.getServer());
28.         }
30.         return serviceInstanceResponse;
31.     }
33.     private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {
34.         if (instances.isEmpty()) {
35.             if (log.isWarnEnabled()) {
36.                 log.warn("No servers available for service: " + this.serviceId);
37.             }
39.             return new EmptyResponse();
40.         } else {
42.             int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;
43.             ServiceInstance instance = instances.get(pos % instances.size());
44.             log.info("serverName:{} upCount:{}",instance.getServiceId(),instances.size());
45.             log.info("feign rule ---> serverName:{}, final server ip:{}:{}", instance.getServiceId(), instance.getHost(),instance.getPort());
46.             return new DefaultResponse(instance);
47.         }
48.     }
49. }

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2.修改LoadBalancerClients配置

1. @Configuration
2. @LoadBalancerClients(defaultConfiguration = CustomLoadBalancerConfiguration.class)
3. public class CustomLoadBalancerConfig {
4. }
6. @Configuration
7. class CustomLoadBalancerConfiguration {
8.     /**
9.      * 参考默认实现
10.      * @see org.springframework.cloud.loadbalancer.annotation.LoadBalancerClientConfiguration#reactorServiceInstanceLoadBalancer
11.      * @return
12.      */
13.     @Bean
14.     public ReactorLoadBalancer<ServiceInstance> reactorServiceInstanceLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {
15.         String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
16.         return new CustomRoundRobinLoadBalancer(loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);
17.     }
18. }

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以上两部完成大功告成！
源码下载：
https://github.com/dongweizhao/spring-cloud-example/tree/SR6-OpenFeign
https://github.com/dongweizhao/spring-cloud-example/tree/EurekaOpenFeign

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