streaming requests on a different host interface than what the apiserver makes requests on (only the case if not using the built-in dockershim & setting the kubelet flag `--redirect-container-streaming=true`), then these requests will be broken. In that case, the feature can be temporarily disabled until the node configuration is corrected. We suggest setting `--redirect-container-streaming=false` on the kubelet to avoid issues.([#72552](https://github.com/kubernetes/kubernetes/pull/72552), [@tallc...

* The Kubelet's deprecated `--allow-privileged` flag now defaults to true. This enables users to stop setting `--allow-privileged` in order to transition to `PodSecurityPolicy`. Previously, users had to continue setting `--allow-privileged`, because the default was false. ([#63442](https://github.com/kubernetes/kubernetes/pull/63442), [@mtaufen](https://github.com/mtaufen))

   ([#122724](https://github.com/kubernetes/kubernetes/pull/122724), [@nayihz](https://github.com/nayihz))
- In the Pod API, setting the alpha `procMount` field to `Unmasked` in a container now required setting `spec.hostUsers=false` as well.
   ([#123520](https://github.com/kubernetes/kubernetes/pull/123520), [@haircommander](https://github.com/haircommander))

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

By default, the `fsgroup` setting, if specified, recursively updates permissions for every file in a volume on every mount. This can make mount, and pod startup, very slow if the volume has many files. 

* When the `PodShareProcessNamespace` alpha feature is enabled, setting `pod.Spec.ShareProcessNamespace` to `true` will cause a single process namespace to be shared between all containers in a pod. ([#58716](https://github.com/kubernetes/kubernetes/pull/58716), [@verb](https://github.com/verb))

* Introduce a new flag `--keepalive` for kubectl proxy to allow setting keep-alive period for long-running request. ([#63793](https://github.com/kubernetes/kubernetes/pull/63793), [@hzxuzhonghu](https://github.com/hzxuzhonghu))

   consuming metrics via an aggregated version of the resource metrics API.

   - In version 1.8, enable this behavior by setting the
     `--horizontal-pod-autoscaler-use-rest-clients` flag to `true`.

   - In version 1.9, this behavior will be enabled by default, and must be explicitly
     disabled by setting the `--horizontal-pod-autoscaler-use-rest-clients` flag to `false`.

### Cluster Lifecycle

  updated. ([#120492](https://github.com/kubernetes/kubernetes/pull/120492), [@cezarygerard](https://github.com/cezarygerard))

- Avoid caching the Azure VMSS instances whose network profile is nil ([#100948](https://github.com/kubernetes/kubernetes/pull/100948), [@feiskyer](https://github.com/feiskyer)) [SIG Cloud Provider]
- Azure: avoid setting cached Sku when updating VMSS and VMSS instances ([#102005](https://github.com/kubernetes/kubernetes/pull/102005), [@feiskyer](https://github.com/feiskyer)) [SIG Cloud Provider]

deprecated, and will be removed in a future release. The default behavior (proxy streaming requests through the kubelet) will be the only supported option. If you are setting `--redirect-container-streaming=true`, then you must migrate off this configuration. The flag will no longer be able to be enabled starting in v1.20. If you are not setting the flag, no action is necessary. ([#88290](https://github.com/kubernetes/kubernetes/pull/88290), [@tallclair](https://github.com/tallclair)) [SIG API Machinery...