1. K8s集群证书续签（kubeadm）步骤：
    2. # 查看证书有效期
    3. kubeadm certs check-expiration
    4. # 备份旧证书
    5. cp -r /etc/kubernetes/pki /etc/kubernetes/pki.old
    6. # 续签证书
    7. kubeadm certs renew all
    8. # 更新kubectl配置
    9. cp -f /etc/kubernetes/admin.conf $HOME/.kube/config
    10. # 重启相关服务，使用新的证书
    11. docker ps | egrep "etcd|kube-apiserver|kube-controller-manager|kube-scheduler" |awk '!/pause/{print $1}' |xargs -i docker restart {}