[root@k8s-master ~]# kubectl get nodes
E0322 10:29:10.166586    8455 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp [::1]:8080: connect: connection refused
E0322 10:29:10.166882    8455 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp [::1]:8080: connect: connection refused
E0322 10:29:10.168298    8455 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp [::1]:8080: connect: connection refused
E0322 10:29:10.170502    8455 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp [::1]:8080: connect: connection refused
E0322 10:29:10.172351    8455 memcache.go:265] couldn't get current server API group list: Get "http://localhost:8080/api?timeout=32s": dial tcp [::1]:8080: connect: connection refused
The connection to the server localhost:8080 was refused - did you specify the right host or port?

单从报错可以看出，kubectl 没有使用到证书与k8s api通信，在初始化集群的时候要想使用kubectl需要，申明证书变量 export KUBECONFIG=/etc/kubernetes/admin.conf ，重启之后 KUBECONFIG 变量失效了。所有需要重新声明，并加入过/etc/profile 全局变量文件。

echo "export KUBECONFIG=/etc/kubernetes/kubelet.conf" >> /etc/profile
source /etc/profile

[root@k8s-master ~]# kubectl get nodes
NAME         STATUS   ROLES           AGE   VERSION
k8s-master   Ready    control-plane   15m   v1.28.2