k8s 1.18.8版本kubeconfig过期，重新更新证书，

查看证书到期时间

kubeadm alpha certs check-expiration

重置证书有效期一年

kubeadm alpha certs renew all

重启相关容器使证书生效

docker ps |grep -E 'k8s_kube-apiserver|k8s_kube-controller-manager|k8s_kube-scheduler|k8s_etcd_etcd' | awk -F ' ' '{print $1}' |xargs docker restart

替换原先kubeconfig

cp /etc/kubernetes/admin.conf /root/.kube/config