k8s证书过期问题处理(Unable to connect to the server: x509: certificate has expired or is not yet valid)
问题：k8s证书过期
[root@nb001 ~]# kubectl get pod -A
Unable to connect to the server: x509: certificate has expired or is not yet valid: current time 2025-05-14T15:52:59+08:00 is after 2025-05-14T02:23:24Z
解决方案
更新证书
执行步骤汇总
# 备份 kubernetes配置
cp -r /etc/kubernetes /etc/kubernetes_bak
# 检测证书是否过期
kubeadm certs check-expiration
# 更新证书
kubeadm certs renew all
步骤执行详情
root@master:~# date
2025年 05月 14日 星期三 15:55:44 CST
root@master:~# cp -r /etc/kubernetes /etc/kubernetes_bak
root@master:/etc# kubeadm certs check-expiration
[check-expiration] Reading configuration from the cluster...
[check-expiration] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[check-expiration] Error reading configuration from the Cluster. Falling back to default configuration
CERTIFICATE EXPIRES RESIDUAL TIME CERTIFICATE AUTHORITY EXTERNALLY MANAGED
admin.conf May 14, 2025 02:23 UTC <invalid> ca no
apiserver May 14, 2025 02:23 UTC <invalid> ca no
apiserver-etcd-client May 14, 2025 02:23 UTC <invalid> etcd-ca no
apiserver-kubelet-client May 14, 2025 02:23 UTC <invalid> ca no
controller-manager.conf May 14, 2025 02:23 UTC <invalid> ca no
etcd-healthcheck-client May 14, 2025 02:23 UTC <invalid> etcd-ca no
etcd-peer May 14, 2025 02:23 UTC <invalid> etcd-ca no
etcd-server May 14, 2025 02:23 UTC <invalid> etcd-ca no
front-proxy-client May 14, 2025 02:23 UTC <invalid> front-proxy-ca no
scheduler.conf May 14, 2025 02:23 UTC <invalid> ca no
CERTIFICATE AUTHORITY EXPIRES RESIDUAL TIME EXTERNALLY MANAGED
ca May 12, 2034 02:23 UTC 8y no
etcd-ca May 12, 2034 02:23 UTC 8y no
front-proxy-ca May 12, 2034 02:23 UTC 8y no
如上，发现很多证书都是<invalid>的状态，接着更新证书：
root@master:/etc# kubeadm certs renew all
[renew] Reading configuration from the cluster...
[renew] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[renew] Error reading configuration from the Cluster. Falling back to default configuration
certificate embedded in the kubeconfig file for the admin to use and for kubeadm itself renewed
certificate for serving the Kubernetes API renewed
certificate the apiserver uses to access etcd renewed
certificate for the API server to connect to kubelet renewed
certificate embedded in the kubeconfig file for the controller manager to use renewed
certificate for liveness probes to healthcheck etcd renewed
certificate for etcd nodes to communicate with each other renewed
certificate for serving etcd renewed
certificate for the front proxy client renewed
certificate embedded in the kubeconfig file for the scheduler manager to use renewed
Done renewing certificates. You must restart the kube-apiserver, kube-controller-manager, kube-scheduler and etcd, so that they can use the new certificates.
更新证书后，再执行kubeadm certs check-expiration命令发现到期时间已经延迟365天
root@master:/etc# kubeadm certs check-expiration
[check-expiration] Reading configuration from the cluster...
[check-expiration] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
W0514 16:07:02.140012 22462 utils.go:69] The recommended value for "resolvConf" in "KubeletConfiguration" is: /run/systemd/resolve/resolv.conf; the provided value is: /run/systemd/resolve/resolv.conf
CERTIFICATE EXPIRES RESIDUAL TIME CERTIFICATE AUTHORITY EXTERNALLY MANAGED
admin.conf May 14, 2026 08:06 UTC 364d ca no
apiserver May 14, 2026 08:06 UTC 364d ca no
apiserver-etcd-client May 14, 2026 08:06 UTC 364d etcd-ca no
apiserver-kubelet-client May 14, 2026 08:06 UTC 364d ca no
controller-manager.conf May 14, 2026 08:06 UTC 364d ca no
etcd-healthcheck-client May 14, 2026 08:06 UTC 364d etcd-ca no
etcd-peer May 14, 2026 08:06 UTC 364d etcd-ca no
etcd-server May 14, 2026 08:06 UTC 364d etcd-ca no
front-proxy-client May 14, 2026 08:06 UTC 364d front-proxy-ca no
scheduler.conf May 14, 2026 08:06 UTC 364d ca no
CERTIFICATE AUTHORITY EXPIRES RESIDUAL TIME EXTERNALLY MANAGED
ca May 12, 2034 02:23 UTC 8y no
etcd-ca May 12, 2034 02:23 UTC 8y no
front-proxy-ca May 12, 2034 02:23 UTC 8y no
新的问题①及解决方案 error: You must be logged in to the server (Unauthorized)
更新完证书后，再执行kubectl get pod -A命令报错
root@master:~# kubectl get pod -A
error: You must be logged in to the server (Unauthorized)
备份配置文件 cp -rp $HOME/.kube/config $HOME/.kube/config.bak ，并生成新的配置文件sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
执行kubectl get pod -A查看解决结果
root@master:~# kubectl get pod -A
error: You must be logged in to the server (Unauthorized)
root@master:~# cp -rp $HOME/.kube/config $HOME/.kube/config.bak
root@master:~#
root@master:~# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
cp：是否覆盖'/root/.kube/config'？ y
root@master:~#
root@master:~# kubectl get pod -A
NAMESPACE NAME READY STATUS RESTARTS AGE
default keycloak-deployment-54bf744955-v9chg 1/1 Running 0 331d
新的问题②及解决方案
上述问题解决后，执行kubectl apply、kubectl create命令可以正常执行，但无法实际操作资源
换句话说：就是执行了，但没生效
举例： 比如你更新service-user.yaml调整了镜像版本，想重新部署下user服务。执行kubectl apply -f service-user.yaml ，但实际pod还是上次部署的pod，并没有重新部署。其余不生效的情况类似。
解决方案：
- 重启kubelet
systemctl restart kubelet
- 重启kube-apiserver、kube-controller-manage、kube-scheduler
# 如果是docker作为容器的话，可执行如下命令。其余容器方法类似
docker ps |grep kube-apiserver|grep -v pause|awk '{print $1}'|xargs -i docker restart {}
docker ps |grep kube-controller-manage|grep -v pause|awk '{print $1}'|xargs -i docker restart {}
docker ps |grep kube-scheduler|grep -v pause|awk '{print $1}'|xargs -i docker restart {}
- 重新部署user服务即可
至此，由于k8s证书过期引起的问题得到彻底解决。
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