k8s 集群证书有效期查看及证书替换修改年限（仅限更新后日期保存一年）

集群版本  v1.18.8

检查证书过期时间

for item in `find /etc/kubernetes/pki -maxdepth 2 -name "*.crt"`;do openssl x509 -in $item -text -noout| grep Not;echo ======================$item===============;done

1，生成集群的配置文件及查看

kubeadm config view > /tmp/cluster.yaml

2，备份原有证书

cp -rp /etc/kubernetes /etc/kubernetes.bak

3，备份etcd数据目录

cp -r /var/lib/etcd /var/lib/etcd.bak

4，更新证书

kubeadm alpha certs renew all --config=/tmp/cluster.yaml

5，使其生效，Master上执行重启kube-apiserver,kube-controller,kube-scheduler,etcd这4个容器，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