* Fixed the webhook admission plugin so that webhook author could use the DNS name of the service as the CommonName when generating the server cert for the webhook.
    * Action required:

    * Fixed the webhook admission plugin so that webhook author could use the DNS name of the service as the CommonName when generating the server cert for the webhook.
    * Action required:

pull/57902), [@kawych](https://github.com/kawych))

* On cluster provision or upgrade, kubeadm now generates certs and secures all connections to the etcd static-pod with mTLS. This includes the etcd serving cert, the etcd peer cert, and the apiserver etcd client cert. Flags and hostMounts are added to the etcd and apiserver static-pods to load these certs. For connections to etcd, https is now used in favor of http. ([#57415](https://github.com/kubernetes/kubernetes/pull/57415), [@s...

* genericapiserver: cut off certificates api dependency ([#39947](https://github.com/kubernetes/kubernetes/pull/39947), [@sttts](https://github.com/sttts))
* genericapiserver: extract CA cert from server cert and SNI cert chains ([#39022](https://github.com/kubernetes/kubernetes/pull/39022), [@sttts](https://github.com/sttts))

certificates directory as `kubelet-client.key` and `kubelet-client.crt`.  Subsequent certificates created by cert rotation were created in a combined PEM file that was atomically rotated as `kubelet-client-DATE.pem` in that directory, which meant clients relying on the `node.kubeconfig` generated by bootstrapping would never use a rotated cert.  The initial bootstrap certificate is now generated into the cert directory as a PEM file and symlinked to `kubelet-client-current.pem` so that the generated kubeconfig...

- The CSR signing cert/key pairs will be reloaded from disk like the kube-apiserver cert/key pairs ([#86816](https://github.com/kubernetes/kubernetes/pull/86816), [@deads2k](https://github.com/deads2k)) [SIG API Machinery, Apps and Auth]

- kube-controller-manager currently needs a writable `--cert-dir` (default is `/var/run/kubernetes`) for generating self-signed certificates, when no `--tls-cert-file` or `--tls-private-key-file` are provided.

* kubeadm: add back `--cert-dir` option for `kubeadm init phase certs sa` ([#73239](https://github.com/kubernetes/kubernetes/pull/73239), [@mattkelly](https://github.com/mattkelly))

- The kube-controller-manager managed signers can now have distinct signing certificates and keys.  See the help about `--cluster-signing-[signer-name]-{cert,key}-file`.  `--cluster-signing-{cert,key}-file` is still the default. ([#90822](https://github.com/kubernetes/kubernetes/pull/90822), [@deads2k](https://github.com/deads2k)) [SIG API Machinery, Apps and Auth]

- kubeadm still generates RSA keys when deploying a node, but also accepts ECDSA
keys if they already exist in the directory specified in the `--cert-dir` option. ([#76390](https://github.com/kubernetes/kubernetes/pull/76390), [@rojkov](https://github.com/rojkov))