on a node host or move it to a safe location. `kubadm certs renew` will renew the certificate in `super-admin.conf` to one year if the file exists; if it does not exist a "MISSING" note will be printed. `kubeadm upgrade apply` for this release will migrate this particular node to the two file setup. Subsequent kubeadm releases will continue to optionally renew the certificate in `super-admin.conf` if the file exists on disk and if renew on upgrade is not disabled. `kubeadm join --control-plane` will...

  - Some kubeadm commands are now allowed to work in a completely offline mode.
- Certificate handling improvements:
  - Renew certs as part of upgrade.
  - New `kubeadm alpha phase certs renew` command for renewing certificates.
  - Certificates created with kubeadm now have improved uniqueness of Distinguished Name fields.
- HA improvements:

- `kubeadm alpha certs renew --csr-only` now reads the current certificates as the authoritative source for certificates attributes (same as kubeadm alpha certs renew). ([#77780](https://github.com/kubernetes/kubernetes/pull/77780), [@fabriziopandini](https://github.com/fabriziopandini))

- Kubelet now exports a `server_expiration_renew_failure` and `client_expiration_renew_failure` metric counter if the certificate rotations cannot be performed. ([#84614](https://github.com/kubernetes/kubernetes/pull/84614), [@rphillips](https://github.com/rphillips)) [SIG API Machinery, Auth, CLI, Cloud Provider,...

- Enable cAdvisor ProcessMetrics collecting. ([#79002](https://github.com/kubernetes/kubernetes/pull/79002), [@jiayingz](https://github.com/jiayingz))
- kubelet: change `node-lease-renew-interval` to 0.25 of lease-renew-duration ([#80429](https://github.com/kubernetes/kubernetes/pull/80429), [@gaorong](https://github.com/gaorong))

- Added option to create CSRs instead of certificates for kubeadm init phase certs and kubeadm alpha certs renew ([#70809](https://github.com/kubernetes/kubernetes/pull/70809), [@liztio](https://github.com/liztio))

- Remove the deprecated flags `--csr-only` and `--csr-dir` from `kubeadm certs renew`. Please use `kubeadm certs generate-csr` instead. ([#104796](https://github.com/kubernetes/kubernetes/pull/104796), [@RA489](https://github.com/RA489))

- The commands `kubeadm certs renew` and `kubeadm certs check-expiration` now honor the `cert-dir` flag on a running Kubernetes cluster. ([#110709](https://github.com/kubernetes/kubernetes/pull/110709), [@chendave](https://github.com/chendave))

- Kube-apiserver now maintains a Lease object to identify itself: 
  - The feature is under feature gate `APIServerIdentity`. 
  - Two flags are added to kube-apiserver: `identity-lease-duration-seconds`, `identity-lease-renew-interval-seconds` ([#95533](https://github.com/kubernetes/kubernetes/pull/95533), [@roycaihw](https://github.com/roycaihw)) [SIG API Machinery]

* Fix error in `kubeadm join --discovery-file` when using discovery files with embedded credentials ([#80675](https://github.com/kubernetes/kubernetes/pull/80675), [@fabriziopandini](https://github.com/fabriziopandini))
* make node lease renew interval more heuristic based on node-status-update-frequency in kubelet ([#80173](https://github.com/kubernetes/kubernetes/pull/80173), [@gaorong](https://github.com/gaorong))