CentOS系统上Nacos服务启动报错：java.net.UnknownHostException: jmenv.tbsite.net

报错描述：

Caused by: com.alibaba.nacos.api.exception.NacosException: java.net.UnknownHostException: jmenv.tbsite.net
	at com.alibaba.nacos.core.cluster.lookup.AddressServerMemberLookup.run(AddressServerMemberLookup.java:122)
	at com.alibaba.nacos.core.cluster.lookup.AddressServerMemberLookup.start(AddressServerMemberLookup.java:74)
	at com.alibaba.nacos.core.cluster.ServerMemberManager.initAndStartLookup(ServerMemberManager.java:154)
	at com.alibaba.nacos.core.cluster.ServerMemberManager.init(ServerMemberManager.java:143)
	at com.alibaba.nacos.core.cluster.ServerMemberManager.<init>(ServerMemberManager.java:128)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:175)
	... 114 common frames omitted
Caused by: java.net.UnknownHostException: jmenv.tbsite.net
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:607)
	at sun.net.NetworkClient.doConnect(NetworkClient.java:175)
	at sun.net.www.http.HttpClient.openServer(HttpClient.java:463)
	at sun.net.www.http.HttpClient.openServer(HttpClient.java:558)
	at sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
	at sun.net.www.http.HttpClient.New(HttpClient.java:339)
	at sun.net.www.http.HttpClient.New(HttpClient.java:357)
	at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1228)
	at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1162)
	at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1056)
	at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:990)
	at com.alibaba.nacos.common.http.client.request.JdkHttpClientRequest.execute(JdkHttpClientRequest.java:112)
	at com.alibaba.nacos.common.http.client.NacosRestTemplate.execute(NacosRestTemplate.java:482)
	at com.alibaba.nacos.common.http.client.NacosRestTemplate.get(NacosRestTemplate.java:72)
	at com.alibaba.nacos.core.cluster.lookup.AddressServerMemberLookup.syncFromAddressUrl(AddressServerMemberLookup.java:145)
	at com.alibaba.nacos.core.cluster.lookup.AddressServerMemberLookup.run(AddressServerMemberLookup.java:113)
	... 123 common frames omitted

原因分析：

原来是nacos启动模式未设置导致的，在没有使用-n参数去指定 Nacos Server 的名称的情况下，Nacos默认会将自己注册到一个命名空间为"jmenv.tbsite.net"的服务中心中。如果你的服务器无法连接到该服务中心，就会导致启动失败。而通过指定-m standalone参数，启动Nacos单机模式，就可以避免这个问题，因为在单机模式下，Nacos不会去注册到任何服务中心中，而是直接启动自己的服务。

解决

启动时指定参数-m standalone单机模式启动就可以了

sh startup.sh -m standalone