springboot微服务连接nacos超时
问题现象
java应用启动失败，查看日志，发现是连接Nacos超时，获取不到配置，导致dubbo注册失败，错误日志如下：
2025-05-01 14:50:08.973 ERROR [TW-172.29.245.61-9063-3] [com.alibaba.nacos.common.utils.LoggerUtils.printIfErrorEnabled:102] c.a.nacos.common.remote.client.grpc.GrpcClient - Server check fail, please check server 172.29.242.158 ,port 9848 is available , error ={}
java.util.concurrent.TimeoutException: Waited 3000 milliseconds (plus 147164 nanoseconds delay) for com.alibaba.nacos.shaded.io.grpc.stub.ClientCalls$GrpcFuture@5fcf7541[status=PENDING, info=[GrpcFuture{clientCall=PendingCall{realCall=ClientCallImpl{method=MethodDescriptor{fullMethodName=Request/request, type=UNARY, idempotent=false, safe=false, sampledToLocalTracing=true, requestMarshaller=com.alibaba.nacos.shaded.io.grpc.protobuf.lite.ProtoLiteUtils$MessageMarshaller@720ff3a9, responseMarshaller=com.alibaba.nacos.shaded.io.grpc.protobuf.lite.ProtoLiteUtils$MessageMarshaller@7f335908, schemaDescriptor=com.alibaba.nacos.api.grpc.auto.RequestGrpc$RequestMethodDescriptorSupplier@1b679ea8}}}}]]at com.alibaba.nacos.shaded.com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:508)at com.alibaba.nacos.common.remote.client.grpc.GrpcClient.serverCheck(GrpcClient.java:218)at com.alibaba.nacos.common.remote.client.grpc.GrpcClient.connectToServer(GrpcClient.java:329)at com.alibaba.nacos.common.remote.client.RpcClient.start(RpcClient.java:363)at com.alibaba.nacos.client.config.impl.ClientWorker$ConfigRpcTransportClient.ensureRpcClient(ClientWorker.java:891)at com.alibaba.nacos.client.config.impl.ClientWorker$ConfigRpcTransportClient.getOneRunningClient(ClientWorker.java:1038)at com.alibaba.nacos.client.config.impl.ClientWorker$ConfigRpcTransportClient.queryConfig(ClientWorker.java:946)at com.alibaba.nacos.client.config.impl.ClientWorker.getServerConfig(ClientWorker.java:403)at com.alibaba.nacos.client.config.NacosConfigService.getConfigInner(NacosConfigService.java:184)
--at com.tongweb.web.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1642)at com.tongweb.web.util.net.SocketProcessorBase.run(SocketProcessorBase.java:33)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)at com.tongweb.web.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:47)at java.lang.Thread.run(Thread.java:748)排查思路
1.网络问题
因为连接超时，第一反应就是网络或者端口不通，通过telnet命令排查，发现正常
telnet 172.29.242.145 8848 # 测试Http端口
telnet 172.29.242.145 9848 # 测试gRPC端口2.域名解析
已排除网络和端口，那么可能是连接真的超时了，超时时间是3s。
（1）解析本机ip
（2）发请求到nacos服务端
（3）服务端返回数据
通过hostname -i命令本机ip，发现大概4~5秒才返回，明显有问题，使用hostname查看主机名称，然后通过cat /etc/hosts命令查看host，发现主机名称没有配置host；加上host，重启服务，能正常注册，问题解决。
hostname -i # 查看主机ip
hostname # 查看主机名称
cat /etc/hosts # 查看host文件