- Pod process namespace sharing is now Generally Available. The `PodShareProcessNamespace` feature gate is now deprecated and will be removed in Kubernetes 1.19. ([#84356](https://github.com/kubernetes/kubernetes/pull/84356), [@verb](https://github.com/verb))
- Fix handling tombstones in pod-disruption-budged controller. ([#83951](https://github.com/kubernetes/kubernetes/pull/83951), [@zouyee](https://github.com/zouyee))

- `kubectl alpha debug` now supports debugging nodes by creating a debugging container running in the node's host namespaces. ([#92310](https://github.com/kubernetes/kubernetes/pull/92310), [@verb](https://github.com/verb)) [SIG CLI]

- Ephemeral containers graduated to beta and are now available by default. ([#105405](https://github.com/kubernetes/kubernetes/pull/105405), [@verb](https://github.com/verb))

* Adds a metric apiserver_request_error_total to kube-apiserver. This metric tallies the number of request_errors encountered by verb, group, version, resource, subresource, scope, component, and code. ([#84780](https://github.com/kubernetes/kubernetes/pull/84780), [@RainbowMango](https://github.com/RainbowMango))

### Feature

- Added KMS `v2alpha1` API. ([#110201](https://github.com/kubernetes/kubernetes/pull/110201), [@aramase](https://github.com/aramase))

  If the API server does not support or allow streaming, then `client-go` falls back to fetching the collection using the **list** API verb. ([#127388](https://github.com/kubernetes/kubernetes/pull/127388), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery and Testing]

- Registered metric `apiserver_request_body_size_bytes` to track the size distribution of requests by `resource` and `verb`. ([#120474](https://github.com/kubernetes/kubernetes/pull/120474), [@YaoC](https://github.com/YaoC)) [SIG API Machinery and Instrumentation]

- Pod spread constraints have been added in alpha. You can use these constraints to control how Pods are spread across the cluster among failure-domains. ([#77327](https://github.com/kubernetes/kubernetes/pull/77327), [#77760](...

### Feature

- A new client side metric `rest_client_request_retries_total` has been added that tracks the number of retries sent to the server, partitioned by status code, verb and host ([#108396](https://github.com/kubernetes/kubernetes/pull/108396), [@tkashem](https://github.com/tkashem))

    * `kubectl delete node/<nodeName>`
    * or grant self-deletion permission explicitly:
        * `kubectl create clusterrole self-deleting-nodes --verb=delete --resource=nodes`
        * `kubectl create clusterrolebinding self-deleting-nodes --clusterrole=self-deleting-nodes --group=system:nodes`