• https://kubernetes.io/docs/reference/setup-tools/kubeadm/

kubeadm bootstraps a cluster (init, join) and handles some of its lifecycle (upgrade, certs, reset). Building a cluster from scratch is covered in Creating Kubernetes clusters. This section covers what comes after.

Guides¶

• Reset a kubeadm cluster or node: what kubeadm reset does and doesn't clean up, the full teardown order, and re-joining.
• Change node IP addresses: re-addressing a control-plane node, including certificates.

Quick reference¶

sudo kubeadm token create --print-join-command   # new worker join command
sudo kubeadm token list
sudo kubeadm certs check-expiration              # control-plane cert expiry (1 year by default)
sudo kubeadm certs renew all                     # then restart the control-plane static pods
sudo kubeadm upgrade plan
kubectl -n kube-system get cm kubeadm-config -o yaml   # the ClusterConfiguration in use

Control-plane certificates are renewed automatically by kubeadm upgrade. A cluster that is never upgraded hits certificate expiry after one year, at which point kubectl starts failing with x509 errors.