- Implemented API for streaming for the `etcd` store implementation.

  * [alpha] CRI now supports specifying the GID of the container at both LinuxSandboxSecurityContext and LinuxContainerSecurityContext in addition to specifying the UID. Support is implemented for dockershim. [@krmayankk]

- Added reconstruction of SELinux mount context after kubelet restart. Feature `SELinuxMountReadWriteOncePod` is now fully implemented and kubelet does not lose its cache of SELinux contexts after kubelet process restart. ([#113596](https://github.com/kubernetes/kubernetes/pull/113596), [@jsafrane](https://github.com/jsafrane))

- Implemented alpha support for a drop-in kubelet configuration directory. ([#119390](https://github.com/kubernetes/kubernetes/pull/119390), [@sohankunkerkar](https://github.com/sohankunkerkar))

- Kubeadm: implemented structured output of 'kubeadm config images list' command in JSON, YAML, Go template and JsonPath formats ([#86810](https://github.com/kubernetes/kubernetes/pull/86810), [@bart0sh](https://github.com/bart0sh)) [SIG Cluster Lifecycle]

- Graduated the container resource metrics feature on `HPA` to beta. ([#116046](https://github.com/kubernetes/kubernetes/pull/116046), [@sanposhiho](https://github.com/sanposhiho))
- Implemented API streaming for the `watch-cache`
  

debugging, similar to how `kubectl exec` runs a process in an existing container. Also like `kubectl exec`, no resources are reserved for ephemeral containers and they are not restarted when they exit. Note that container namespace targeting is not yet implemented, so [process namespace sharing](https://kubernetes.io/docs/tasks/configure-pod-container/share-process-namespace/) must be enabled to view process from other containers in the pod. ([#59484](https://github.com/kubernetes/kubernetes/pull/59484),...

### IPv4/IPv6 run

## Changelog since v1.18.0

## What’s New (Major Themes)

### Deprecation warnings

SIG API Machinery implemented [warnings when using deprecated APIs](https://kubernetes.io/docs/reference/using-api/deprecation-policy/#rest-resources-aka-api-objects)

    legacy_request_state_context_var.reset(contextvar_token)
```

...before this change it would raise an error when resetting the context variable, because the `contextvars` context was different, because of the way it was implemented.

**Note**: You probably don't need `contextvars`, and you should probably avoid using them. But they are powerful and useful in some advanced scenarios, for example, migrating from code that used Flask's `g` semi-global variable.