- 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.

## 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]

- Removed generally available feature gate `CSINodeExpandSecret`. ([#124462](https://github.com/kubernetes/kubernetes/pull/124462), [@carlory](https://github.com/carlory))
- Removed generally available feature gate `ConsistentHTTPGetHandlers`. ([#124463](https://github.com/kubernetes/kubernetes/pull/124463), [@carlory](https://github.com/carlory))

* 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))

* [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))

* [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

- 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]

    * Change chain name to IP-MASQ to be compatible with the pre-injected masquerade rules.
* If `TaintNodesByCondition` is enabled, add `node.kubernetes.io/unschedulable` and `node.kubernetes.io/network-unavailable` automatically to DaemonSet pods. ([#64954](https://github.com/kubernetes/kubernetes/pull/64954), [@k82cn](https://github.com/k82cn))