Features for this release were tracked via the use of the [kubernetes/features](https://github.com/kubernetes/features) issues repo.  Each Feature issue is owned by a Special Interest Group from the [kubernetes/community](https://github.com/kubernetes/community/blob/master/sig-list.md).

### Autoscaling
* **[alpha]** The Horizontal Pod Autoscaler now supports drawing metrics through the API server aggregator.

### Dockershim deprecation

Docker as an underlying runtime is being deprecated. Docker-produced images will continue to work in your cluster with all runtimes, as they always have.
The Kubernetes community [has written a blog post about this in detail](https://blog.k8s.io/2020/12/02/dont-panic-kubernetes-and-docker/) with [a dedicated FAQ page for it](https://blog.k8s.io/2020/12/02/dockershim-faq/).

- New conformance tests added for API Aggregation. ([#63947](https://github.com/kubernetes/kubernetes/pull/63947), [@jennybuckley](https://github.com/jennybuckley))
- Moved fluentd-elasticsearch addon images to community controlled location ([#73819](https://github.com/kubernetes/kubernetes/pull/73819), [@coffeepac](https://github.com/coffeepac))

#### Extensibility

- The community has been asking for continuing support of extensibility, so this cycle features more work around CRDs and API Machinery. Most of the enhancements in this cycle were from SIG API Machinery and related areas.

### OpenStack

SIG-OpenStack updated the OpenStack provider to use newer APIs, consolidated community code into one repository, engaged with the Cloud Provider Working Group to have a consistent plan for moving provider code into individual repositories, improved testing of provider code, and strengthened ties with the OpenStack developer community.

### API-machinery

  <mime-type type="application/marc">
    <!-- todo add marc xml <marc:collection> -->
    <glob pattern="*.mrc"/>
    <magic priority="50">
      <!-- built from, e.g. https://www.loc.gov/marc/community/cileader.html -->
      <match value="[0-9]{5,5}" type="regex" offset="0">
        <match value="45" type="string" offset="20">
          <!-- bibliographic -->

- Docker runtime support using dockershim in the kubelet is now completely removed in 1.24. The kubelet used to have a module called dockershim, which implements CRI support for Docker, and it has seen maintenance issues in the Kubernetes community. From 1.24 onwards, please move to a container runtime that is a full-fledged implementation of CRI (v1alpha1 or v1 compliant) as they become available. ([#97252](https://github.com/kubernetes/kubernetes/pull/97252), [@dims](https://github.com/dims))...

### SIG Windows development tools

## What's New (Major Themes)

### Deprecation of FlexVolume

FlexVolume is deprecated. Out-of-tree CSI driver is the recommended way to write volume drivers in Kubernetes.
See [this doc](https://github.com/kubernetes/community/blob/master/sig-storage/volume-plugin-faq.md#kubernetes-volume-plugin-faq-for-storage-vendors) for more information.
Maintainers of FlexVolume drivers should implement a CSI driver and move users of FlexVolume to CSI.