* When using client or server certificate rotation, the Kubelet will no longer wait until the initial rotation succeeds or fails before starting static pods.  This makes running self-hosted masters with rotation more predictable. ([#58930](https://github.com/kubernetes/kubernetes/pull/58930), [@smarterclayton](https://github.com/smarterclayton))

### GCP

- Fixed liveness probe in fluentd-gcp cluster addon ([#74522](https://github.com/kubernetes/kubernetes/pull/74522), [@Pluies](https://github.com/Pluies))
- Reduced GCE log rotation check from 1 hour to every 5 minutes.  Rotation policy is unchanged (new day starts, log file size > 100MB). ([#72062](https://github.com/kubernetes/kubernetes/pull/72062), [@jpbetz](https://github.com/jpbetz))

### Network

- 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))

* 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.

* Fixed encryption key and encryption provider rotation ([#58375](https://github.com/kubernetes/kubernetes/pull/58375), [@liggitt](https://github.com/liggitt))

#### TLS Bootstrapping
* [alpha] Rotation of the server TLS certificate on the kubelet. See [TLS bootstrapping - approval controller](https://kubernetes.io/docs/admin/kubelet-tls-bootstrapping/#approval-controller).

    - `rest_client_certificate_expiration_seconds` a gauge reporting the lifetime of the current client certificate. Reports the time of expiry in seconds since January 1, 1970 UTC.

- Fixes an issue affecting log rotation with CRI runtimes where kubelet tries to compress Windows logs before closing file handles ([#112483](https://github.com/kubernetes/kubernetes/pull/112483), [@ibabou](https://github.com/ibabou)) [SIG Node and Windows]

and developer experience. There are numerous bug fixes to lease objects causing memory leaks, and compact operation causing deadlocks and more. A couple of new features are also introduced like the migration to structured logging and build in log rotation. The release comes with a detailed future roadmap to implement a solution to traffic overload. A full and detailed list of changes can be read in the [3.5.0 release announcement](https://etcd.io/blog/2021/announcing-etcd-3.5/).

### Kubernetes...

###  Introduced KMS v2