How to renew Kubernetes Certificates 

Error:

 kubelet: E0616 01:31:44.436142    1913 bootstrap.go:265] part of the existing bootstrap client certificate in /etc/kubernetes/kubelet.conf is expired: 2023-06-07 15:06:28 +0000 UTC

Solution:

1. Check Kubernetes Certificate expirateion.

#kubeadm certs check-expiration

Manual certificate renewal

You can renew your certificates manually at any time with the kubeadm certs renew command.

This command performs the renewal using CA (or front-proxy-CA) certificate and key stored in /etc/kubernetes/pki.

#kubeadm certs renew all

You must restart the kube-apiserver, kube-controller-manager, kube-scheduler and etcd, so that they can use the new certificates.