- 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))

  - NetworkPolicy resources will no longer be served from `extensions/v1beta1` in v1.16. Migrate use to the `networking.k8s.io/v1` API, available since v1.8. Existing persisted data can be retrieved via the `networking.k8s.io/v1` API.

* kube-apiserver: requests to endpoints handled by unavailable extension API servers (as indicated by an `Available` condition of `false` in the registered APIService) now return `503` errors instead of `404` errors. ([#58070](https://github.com/kubernetes/kubernetes/pull/58070), [@weekface](https://github.com/weekface))

* [stable] Expose storage usage metrics

  * The available capacity of a given Persistent Volume (PV) is available by calling the Kubernetes metrics API.

* [stable] Volume plugin metrics

## Changes by Kind

### API Change

- Make STS available replicas optional again, ([#109241](https://github.com/kubernetes/kubernetes/pull/109241), [@ravisantoshgudimetla](https://github.com/ravisantoshgudimetla)) [SIG API Machinery and Apps]

- Fix bug that would let the Horizontal Pod Autoscaler scale down despite at least one metric being unavailable/invalid ([#99514](https://github.com/kubernetes/kubernetes/pull/99514), [@mikkeloscar](https://github.com/mikkeloscar)) [SIG Apps and Autoscaling]

* [alpha] Make locally attached (non-network attached) storage available as a persistent volume source. For more information, see [Storage Volumes - local](https://kubernetes.io/docs/concepts/storage/volumes/#local).

#### Volume Plugins

- Kubeadm: improved retries when updating node information, in case `kube-apiserver` is temporarily unavailable ([#114176](https://github.com/kubernetes/kubernetes/pull/114176), [@QuantumEnergyE](https://github.com/QuantumEnergyE))

- Fixed error "dbus: connection closed by user" after dbus daemon restarts. ([#110496](https://github.com/kubernetes/kubernetes/pull/110496), [@kolyshkin](https://github.com/kolyshkin))
- Fixed image pull failure when `IMDS` is unavailable in kubelet startup. ([#110523](https://github.com/kubernetes/kubernetes/pull/110523), [@andyzhangx](https://github.com/andyzhangx))

    - [Dockershim deprecation](#dockershim-deprecation)
    - [External credential provider for client-go](#external-credential-provider-for-client-go)
    - [CronJob controller v2 is available through feature gate](#cronjob-controller-v2-is-available-through-feature-gate)
    - [PID Limits graduates to General Availability](#pid-limits-graduates-to-general-availability)