The dynamic kubelet config feature graduated to beta, so it is enabled by default, simplifying management of the node object itself.  Kubelets that are configured to work with the CRI may take advantage of the log rotation feature, which is graduating to beta this release.

- Reduced GCE log rotation check from 1 hour to every 5 minutes.  Rotation policy is unchanged (new day starts, log file size > 100MB). ([#76352](https://github.com/kubernetes/kubernetes/pull/76352), [@jpbetz](https://github.com/jpbetz))

- Kubeadm: remove the deprecated sub-phase of 'init kubelet-finilize' called `experimental-cert-rotation`, and use 'enable-client-cert-rotation' instead. ([#126913](https://github.com/kubernetes/kubernetes/pull/126913), [@pacoxu](https://github.com/pacoxu)) [SIG Cluster Lifecycle]

)

var (
	// AWS errors for invalid SSE-C requests.
	errEncryptedObject                = errors.New("The object was stored using a form of SSE")
	errInvalidSSEParameters           = errors.New("The SSE-C key for key-rotation is not correct") // special access denied
	errKMSNotConfigured               = errors.New("KMS not configured for a server side encrypted objects")
	errKMSKeyNotFound                 = errors.New("Unknown KMS key ID")

	// - the object is encrypted using SSE-S3 and the SSE-S3 header is present
	// - the object storage class is not changing
	// then execute a key rotation.
	if cpSrcDstSame && (sseCopyC && sseC) && !chStorageClass {
		oldKey, err = ParseSSECopyCustomerRequest(r.Header, srcInfo.UserDefined)
		if err != nil {
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)

* Kubelets using TLS bootstrapping (`--bootstrap-kubeconfig`) or certificate rotation (`--rotate-certificates`) store certificates in the directory specified by `--cert-dir`. The default location (`/var/run/kubernetes`) is automatically erased on reboot on some platforms, which can prevent the kubelet from authenticating to the API server after a reboot. Specifying a non-transient location, such as `--cert-dir=/var/lib/kubelet/pki`, is recommended.

 
## Changes by Kind

### Deprecation

- 'kubeadm: marked the sub-phase of ''init kubelet-finilize'' called ''experimental-cert-rotation''
  as deprecated and print a warning if it is used directly; it will be removed in
  a future release. Add a replacement sub-phase ''enable-client-cert-rotation''.' ([#124419](https://github.com/kubernetes/kubernetes/pull/124419), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

* Fix the bug where StartedAt time is not reported for exited containers. ([#45977](https://github.com/kubernetes/kubernetes/pull/45977), [@yujuhong](https://github.com/yujuhong))
* Enable basic auth username rotation for GCI ([#44590](https://github.com/kubernetes/kubernetes/pull/44590), [@ihmccreery](https://github.com/ihmccreery))

* Actually fix local-cluster-up on 1.5 branch ([#40501](https://github.com/kubernetes/kubernetes/pull/40501), [@lavalamp](https://github.com/lavalamp))
* Prevent hotloops on error conditions, which could fill up the disk faster than log rotation can free space. ([#40497](https://github.com/kubernetes/kubernetes/pull/40497), [@lavalamp](https://github.com/lavalamp))

- Changed core_pattern on COS nodes to be an absolute path. ([#86329](https://github.com/kubernetes/kubernetes/pull/86329), [@mml](https://github.com/mml)) [SIG Cluster Lifecycle and Node]
- Client-go certificate manager rotation gained the ability to preserve optional intermediate chains accompanying issued certificates ([#88744](https://github.com/kubernetes/kubernetes/pull/88744), [@jackkleeman](https://github.com/jackkleeman)) [SIG API Machinery and Auth]