When k8s executes kubectl get nodes on the master node, it prompts:
root@k8s-master01 .kube]# kubectl --kubeconfig=/root/.kube/config get nodes
Unable to connect to the server: x509: certificate has expired or is not yet valid: current time 2022-11-24T16:57:15+08:00 is after 2022-09-16T09:13:17Z
Certificate update command:
kubeadm certs renew all
[root@k8s-master01 ~]# 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'
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.
Verify command:
kubeadm certs check-expiration
[root@k8s-master01 ~]# 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'
CERTIFICATE EXPIRES RESIDUAL TIME CERTIFICATE AUTHORITY EXTERNALLY MANAGED
admin.conf Jul 27, 2023 09:25 UTC 245d ca no
apiserver Jul 27, 2023 09:25 UTC 245d ca no
apiserver-etcd-client Jul 27, 2023 09:25 UTC 245d etcd-ca no
apiserver-kubelet-client Jul 27, 2023 09:25 UTC 245d ca no
controller-manager.conf Jul 27, 2023 09:25 UTC 245d ca no
etcd-healthcheck-client Jul 27, 2023 09:25 UTC 245d etcd-ca no
etcd-peer Jul 27, 2023 09:25 UTC 245d etcd-ca no
etcd-server Jul 27, 2023 09:25 UTC 245d etcd-ca no
front-proxy-client Jul 27, 2023 09:25 UTC 245d front-proxy-ca no
scheduler.conf Jul 27, 2023 09:25 UTC 245d ca no
Find the admin.conf location
[root@k8s-master01 .kube]# find / -name admin.conf
/etc/kubernetes/admin.conf
[root@k8s-master01 .kube]# kubectl --kubeconfig=/etc/kubernetes/admin.conf get nodes\
NAME STATUS ROLES AGE VERSION
k8s-master01 Ready master 433d v1.19.4
k8s-node01 Ready <none> 433d v1.19.4
k8s-node02 Ready <none> 433d v1.19.4
k8s-node03 Ready <none> 433d v1.19.4
Copy admin.conf to /root/.kube/config and execute kubectl get nodes command to verify
[root@k8s-master01 .kube]# cp /etc/kubernetes/admin.conf /root/.kube/config
cp: overwrite '/root/.kube/config'? yes
[root@k8s-master01 .kube]#
[root@k8s-master01 .kube]#
[root@k8s-master01 .kube]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master01 Ready master 433d v1.19.4
k8s-node01 Ready <none> 433d v1.19.4
k8s-node02 Ready <none> 433d v1.19.4
k8s-node03 Ready <none> 433d v1.19.4
