* Removed Alpha feature `MountContainers` ([#84365](https://github.com/kubernetes/kubernetes/pull/84365), [@codenrhoden](https://github.com/codenrhoden))

## Changelog since v1.18.4

## Changes by Kind

### API Change

- Fixed: log timestamps now include trailing zeros to maintain a fixed width ([#91207](https://github.com/kubernetes/kubernetes/pull/91207), [@iamchuckss](https://github.com/iamchuckss)) [SIG Apps and Node]

### Bug or Regression

 - [kube-log-runner](https://github.com/kubernetes/kubernetes/tree/master/staging/src/k8s.io/component-base/logs/kube-log-runner) is included in release tar balls. It can be used to replace the deprecated `--log-file` parameter. ([#106123](https://github.com/kubernetes/kubernetes/pull/106123), [@pohly](https://github.com/pohly)) [SIG API Machinery, Architecture,...

* The kube-apiserver [basic audit log](https://kubernetes.io/docs/admin/audit/) can be enabled in GCE by exporting the environment variable `ENABLE_APISERVER_BASIC_AUDIT=true` before running `cluster/kube-up.sh`. This will log to `/var/log/kube-apiserver-audit.log` and use the same `logrotate` settings as `/var/log/kube-apiserver.log`. ([#41211](https://github.com/kubernetes/kubernetes/pull/41211), [@enisoc](https://github.com/enisoc))...

- If `kube-proxy` mode  is userspace do not enable `EndpointSlices`. ([#100913](https://github.com/kubernetes/kubernetes/pull/100913), [@JornShen](https://github.com/JornShen))

    - [Security Improvements for CSI Drivers (Alpha)](#security-improvements-for-csi-drivers-alpha)
    - [Introducing Graceful Node Shutdown (Alpha)](#introducing-graceful-node-shutdown-alpha)
    - [Runtime log sanitation](#runtime-log-sanitation)
    - [Pod resource metrics](#pod-resource-metrics)
    - [Introducing <code>RootCAConfigMap</code>](#introducing-rootcaconfigmap)

- Kube-apiserver: `--audit-log-version` and `--audit-webhook-version` now only support the default value of `audit.k8s.io/v1`. The v1alpha1 and v1beta1 audit log versions, deprecated since 1.13, have been removed. ([#108092](https://github.com/kubernetes/kubernetes/pull/108092), [@carlory](https://github.com/carlory))

* `framework.ExpectNoError` no longer logs the error and instead relies on using the new `log.Fail` as Gomega fail handler. ([#80253](https://github.com/kubernetes/kubernetes/pull/80253), [@pohly](https://github.com/pohly))
* Audit events now log the existence and patch of mutating webhooks.  ([#77824](https://github.com/kubernetes/kubernetes/pull/77824), [@roycaihw](https://github.com/roycaihw))

* The kube-apiserver [basic audit log](https://kubernetes.io/docs/admin/audit/) can be enabled in GCE by exporting the environment variable `ENABLE_APISERVER_BASIC_AUDIT=true` before running `cluster/kube-up.sh`. This will log to `/var/log/kube-apiserver-audit.log` and use the same `logrotate` settings as `/var/log/kube-apiserver.log`. ([#41211](https://github.com/kubernetes/kubernetes/pull/41211), [@enisoc](https://github.com/enisoc))...

### Other (Cleanup or Flake)

- A v2-level info log will be added, which will output the details of the pod being preempted, including victim and preemptor ([#117214](https://github.com/kubernetes/kubernetes/pull/117214), [@HirazawaUi](https://github.com/HirazawaUi)) [SIG Scheduling]