* Change docker metrics to conform metrics guidelines and using histogram for better aggregation. ([#72323](https://github.com/kubernetes/kubernetes/pull/72323),...

* Introduced `--http2-max-streams-per-connection` command line flag on api-servers and set default to 1000 for aggregated API servers. ([#60054](https://github.com/kubernetes/kubernetes/pull/60054), [@MikeSpreitzer](https://github.com/MikeSpreitzer))

by admission webhooks, custom resource conversion webhooks, and aggregated API servers must now include valid Subject Alternative Names. If you are running Kubernetes 1.22 with `GODEBUG=x509ignoreCN=0` set, check the `apiserver_kube_aggregator_x509_missing_san_total` and `apiserver_webhooks_x509_missing_san_total` metrics for non-zero values to see if the API server is connecting to webhooks or aggregated API servers using certificates that will be considered invalid in Kubernetes 1.23+.

##...

  - Different configuration types can be supplied all in the same file separated by `---`.
- Improved CRI handling
  - crictl is no longer required in docker-only setups.
  - Better detection of installed CRI.
  - Better output for image pull errors.
- Improved air-gapped and offline support
  - kubeadm now handles air-gapped environments by using the local client version as a fallback.

* Portworx Volume Plugin added enabling [Portworx](http://www.portworx.com) to be used as a storage provider for Kubernetes clusters. Portworx pools your servers capacity and turns your servers or cloud instances into converged, highly available compute and storage nodes. ([#39535](https://github.com/kubernetes/kubernetes/pull/39535), [@adityadani](https://github.com/adityadani))

* kube-apiserver now includes all registered API groups in discovery, including registered extension API group/versions for unavailable extension API servers. ([#66932](https://github.com/kubernetes/kubernetes/pull/66932), [@nilebox](https://github.com/nilebox))

## Changelog since v1.16.7

## Changes by Kind

### API Change

- Fixes a regression with clients prior to 1.15 not being able to update podIP in pod status, or podCIDR in node spec, against >= 1.16 API servers ([#88505](https://github.com/kubernetes/kubernetes/pull/88505), [@liggitt](https://github.com/liggitt)) [SIG Apps and Network]

### Other (Bug, Cleanup or Flake)

- API priority and fairness graduated to beta. 1.19 servers with APF turned on should not be run in a multi-server cluster with 1.20+ servers. ([#96527](https://github.com/kubernetes/kubernetes/pull/96527), [@adtac](https://github.com/adtac)) [SIG API Machinery and Testing]

- The getters for the field name and typeDescription of the Reflector struct were renamed. ([#128035](https://github.com/kubernetes/kubernetes/pull/128035), [@alexanderstephan](https://github.com/alexanderstephan)) [SIG API Machinery]

* Fix a bug in server printer that could cause kube-apiserver to panic. ([#79349](https://github.com/kubernetes/kubernetes/pull/79349), [@roycaihw](https://github.com/roycaihw))
* Fix a bug in the IPVS proxier where virtual servers are not cleaned up even though the corresponding Service object was deleted. ([#80942](https://github.com/kubernetes/kubernetes/pull/80942), [@gongguan](https://github.com/gongguan))