升级了nacos客户端的版本之后，启动服务发现注册不上。错误如下：
[ main] c.a.c.n.registry.NacosServiceRegistry : nacos registry, service-provider register failed...
com.alibaba.nacos.api.exception.NacosException: Client not connected, current status:STARTING
at com.alibaba.nacos.common.remote.client.RpcClient.request(RpcClient.java:639) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.nacos.common.remote.client.RpcClient.request(RpcClient.java:619) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.nacos.client.naming.remote.gprc.NamingGrpcClientProxy.requestToServer(NamingGrpcClientProxy.java:356) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.nacos.client.naming.remote.gprc.NamingGrpcClientProxy.doRegisterService(NamingGrpcClientProxy.java:209) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.nacos.client.naming.remote.gprc.NamingGrpcClientProxy.registerService(NamingGrpcClientProxy.java:123) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.nacos.client.naming.remote.NamingClientProxyDelegate.registerService(NamingClientProxyDelegate.java:98) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.nacos.client.naming.NacosNamingService.registerInstance(NacosNamingService.java:152) ~[nacos-client-2.2.0.jar:na]
at com.alibaba.cloud.nacos.registry.NacosServiceRegistry.register(NacosServiceRegistry.java:75) ~[spring-cloud-starter-alibaba-nacos-discovery-2021.0.5.0.jar:2021.0.5.0]
at org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.register(AbstractAutoServiceRegistration.java:232) [spring-cloud-commons-3.1.5.jar:3.1.5]
at com.alibaba.cloud.nacos.registry.NacosAutoServiceRegistration.register(NacosAutoServiceRegistration.java:78) [spring-cloud-starter-alibaba-nacos-discovery-2021.0.5.0.jar:2021.0.5.0]
at org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.start(AbstractAutoServiceRegistration.java:133) [spring-cloud-commons-3.1.5.jar:3.1.5]
at org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.bind(AbstractAutoServiceRegistration.java:98) [spring-cloud-commons-3.1.5.jar:3.1.5]
at org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.onApplicationEvent(AbstractAutoServiceRegistration.java:86) [spring-cloud-commons-3.1.5.jar:3.1.5]
at org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.onApplicationEvent(AbstractAutoServiceRegistration.java:47) [spring-cloud-commons-3.1.5.jar:3.1.5]
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:421) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:378) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.boot.web.servlet.context.WebServerStartStopLifecycle.start(WebServerStartStopLifecycle.java:46) [spring-boot-2.6.13.jar:2.6.13]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) [spring-context-5.3.23.jar:5.3.23]
at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_402]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) [spring-context-5.3.23.jar:5.3.23]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.13.jar:2.6.13]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:745) ~[spring-boot-2.6.13.jar:2.6.13]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:420) ~[spring-boot-2.6.13.jar:2.6.13]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) ~[spring-boot-2.6.13.jar:2.6.13]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1317) ~[spring-boot-2.6.13.jar:2.6.13]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[spring-boot-2.6.13.jar:2.6.13]
at com.aliware.sae.ProviderApplication.main(ProviderApplication.java:15) ~[classes/:na]
调查了半天，原来是跟grpc有关。1.x版本的nacos客户端，只要连接上nacos服务器的8848接口就可以了。但是客户端升级到2.2之后，它还要去连接服务器的另外2个端口。这2个端口是在主端口（一般是8848）上做了一定的偏移自动生成的。参考文章在此。
所以，在docker里面运行nacos的时候，仅仅做8848端口的映射就不够了，还要把9848和9849给打开。对应到命令行上，要多加几个参数了：
docker run --name nacos -d \
-p 8848:8848 \
-p 9848:9848 \
-p 9849:9849 \
打开这几个端口之后，nacos的2.x客户端就能正常连接上2.x的nacos服务端了😊
