背景

想学习使用最新稳定版本的 nacos，即 2.4.3 版本。
docker 部署的 nacos server，使用的单机模式。
新建一个 Spring Cloud 项目启用 Nacos 的服务发现功能。

核心报错信息

nacos服务部署完之后，新建一个Spring Cloud 项目注册到 nacos，项目启动报错：

2024-11-15T16:58:51.307+08:00 ERROR 64955 --- [empty-pom-demo] [remote.worker.1] c.a.n.c.remote.client.grpc.GrpcClient    : Server check fail, please check server 127.0.0.1 ,port 9848 is available , error ={}

java.util.concurrent.ExecutionException: com.alibaba.nacos.shaded.io.grpc.StatusRuntimeException: UNAVAILABLE: io exception
	at com.alibaba.nacos.shaded.com.google.common.util.concurrent.AbstractFuture.getDoneValue(AbstractFuture.java:592) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:467) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.common.remote.client.grpc.GrpcClient.serverCheck(GrpcClient.java:243) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.common.remote.client.grpc.GrpcClient.connectToServer(GrpcClient.java:367) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.common.remote.client.RpcClient.reconnect(RpcClient.java:502) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.common.remote.client.RpcClient.lambda$start$1(RpcClient.java:329) ~[nacos-client-2.3.2.jar:na]
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539) ~[na:na]
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na]
	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) ~[na:na]
	at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
Caused by: com.alibaba.nacos.shaded.io.grpc.StatusRuntimeException: UNAVAILABLE: io exception
	at com.alibaba.nacos.shaded.io.grpc.Status.asRuntimeException(Status.java:537) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.stub.ClientCalls$UnaryStreamToFuture.onClose(ClientCalls.java:548) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.DelayedClientCall$DelayedListener$3.run(DelayedClientCall.java:489) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.DelayedClientCall$DelayedListener.delayOrExecute(DelayedClientCall.java:453) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.DelayedClientCall$DelayedListener.onClose(DelayedClientCall.java:486) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:567) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.ClientCallImpl.access$300(ClientCallImpl.java:71) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInternal(ClientCallImpl.java:735) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:716) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133) ~[nacos-client-2.3.2.jar:na]
	... 3 common frames omitted
Caused by: com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: /127.0.0.1:9848
Caused by: java.net.ConnectException: Connection refused
	at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
	at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[na:na]
	at java.base/sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:946) ~[na:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:337) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:334) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:776) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[nacos-client-2.3.2.jar:na]
	at com.alibaba.nacos.shaded.io.grpc.netty.shaded.io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[nacos-client-2.3.2.jar:na]
	at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]

原因

docker 部署 nacos 没有开放9848和9849端口号。

官网描述

Nacos2.X版本新增了gRPC的通信方式，因此需要增加2个端口。新增端口是在配置的主端口(server.port，默认8848)基础上，进行一定偏移量自动生成，具体端口内容及偏移量请参考如下：

端口 与主端口的偏移量 描述
9848 1000 客户端gRPC请求服务端端口，用于客户端向服务端发起连接和请求
9849 1001 服务端gRPC请求服务端端口，用于服务间同步等
7848 -1000 Jraft请求服务端端口，用于处理服务端间的Raft相关请求
使用VIP/nginx请求时，需要配置成TCP转发，不能配置http2转发，否则连接会被nginx断开。

解决

重新部署nacos，使用以下命令，部署的是单机模式：

docker run -d --name nacos -e  MODE=standalone -p 8848:8848 -p 9848:9848 -p 9849:9849 nacos/nacos-server:v2.4.3