* `federation/deploy/deploy.sh` was an interim solution introduced in Kubernetes v1.4 to simplify the federation control plane deployment experience. Now that we have `kubefed`, we are deprecating `deploy.sh` scripts. ([#38902](https://github.com/kubernetes/kubernetes/pull/38902), [@madhusudancs](https://github.com/madhusudancs))

- kubeadm: promoted feature gate `EtcdLearnerMode` to GA. Learner mode in etcd deployed by kubeadm is now locked to enabled by default. ([#126374](https://github.com/kubernetes/kubernetes/pull/126374), [@pacoxu](https://github.com/pacoxu)) [SIG Cluster Lifecycle]

* The metrics APIs, `custom-metrics.metrics.k8s.io` and `metrics`, were moved from `v1alpha1` to `v1beta1`, and renamed to `custom.metrics.k8s.io` and `metrics.k8s.io`, respectively. If you have deployed a custom metrics adapter, ensure that it supports the new API version. If you have deployed Heapster in aggregated API server mode, upgrade Heapster to support the latest API version.

## Changelog since v1.20.0

## What's New (Major Themes)

### Deprecation of PodSecurityPolicy

Note that snapshot support will require Kubernetes distributors to bundle the Snapshot controller, Snapshot CRDs, and validation webhook. In addition, a CSI driver supporting the snapshot functionality must also be deployed on the cluster.

### Non-recursive Volume Ownership (FSGroup) graduates to Beta

### API Change

- 'ACTION REQUIRED: The Dynamic Resource Allocation (DRA) driver's DaemonSet
  must be deployed with a service account that enables writing ResourceSlice
  and reading ResourceClaim objects.'
   ([#125163](https://github.com/kubernetes/kubernetes/pull/125163), [@pohly](https://github.com/pohly)) [SIG Auth, Node and Testing]

* Updated admission controller settings for Juju deployed Kubernetes clusters ([#61427](https://github.com/kubernetes/kubernetes/pull/61427), [@hyperbolic2346](https://github.com/hyperbolic2346))

  - With the release of the CSI 1.0 API, support for CSI drivers using 0.3 and older releases of the CSI API is deprecated, and is planned to be removed in Kubernetes v1.15. CSI drivers should be updated to support the CSI 1.0 API, and deployed in the new kubelet plugin registration directory (`{kubelet_root_dir}/plugins_registry/`) once all nodes in the cluster are at 1.13 or higher ([#71020](https://github.com/kubernetes/kubernetes/pull/71020) and [#71314](https://github.com/kubernet...

 - `kubeadm`: a separate "super-admin.conf" file is now deployed. The User in `admin.conf` is now bound to a new RBAC Group `kubeadm:cluster-admins` that has `cluster-admin` `ClusterRole` access. The User in `super-admin.conf` is now bound to the `system:masters` built-in super-powers / break-glass Group that...

- Eliminated work when creating Services or understanding port purposes, especially for external resources deployed via Helm charts. ([#133018](https://github.com/kubernetes/kubernetes/pull/133018), [@rushmash91](https://github.com/rushmash91))