* Bug fixes

  * Fixes issue with Flexvolume, introduced in 1.6.0, where drivers without an attacher would fail (node indefinitely waiting for attach). A driver API addition is introduced: drivers that don't implement attach should return attach: false on init. ([#47503](https://github.com/kubernetes/kubernetes/pull/47503), [@chakri-nelluri](https://github.com/chakri-nelluri))

    * ACTION REQUIRED: the alpha CRDs are no longer used and drivers will need to be updated to use the beta APIs.
    * The support for `_` in the CSI driver name will be dropped as the CSI Spec does not allow that. 

### Other notable changes

  passed a file which contains RBAC roles, rolebindings, clusterroles, or
  clusterrolebindings, this command computes covers and adds the missing rules.
  The logic required to properly apply RBAC permissions is more complicated
  than a JSON merge because you have to compute logical covers operations between
  rule sets. This means that we cannot use `kubectl apply` to update RBAC roles

- Metric names for CSI and flexvolume drivers will include the driver name as well as the CSI plugin name. ([#96474](https://github.com/kubernetes/kubernetes/pull/96474), [@mattcary](https://github.com/mattcary)) [SIG Instrumentation and Storage]

### Action Required

* ACTION REQUIRED: Removes defaulting of CSI file system type to ext4. All the production drivers listed under https://kubernetes-csi.github.io/docs/drivers.html were inspected and should not be impacted after this change. If you are using a driver not in that list, please test the drivers on an updated test cluster first. ``` ([#65499](https://github.com/kubernetes/kubernetes/pull/65499), [@krunaljain](https://github.com/krunaljain))

- NFS Drivers are now enabled to collect metrics, StatFS metrics provider is used to collect the metrics. (@brahmaroutu) ([#75805](https://github.com/kubernetes/kubernetes/pull/75805), [@brahmaroutu](https://github.com/brahmaroutu))

* Flex volume plugin is updated to support attach/detach interfaces. It broke backward compatibility. Please update your drivers and implement the new callouts.  ([#41804](https://github.com/kubernetes/kubernetes/pull/41804), [@chakri-nelluri](https://github.com/chakri-nelluri))

## Notable Features

### Feature

- 'Added selector validation to `HorizontalPodAutoscaler`: when multiple HPAs
  select the same set of Pods, scaling now will be disabled for those HPAs with
  the reason `AmbiguousSelector`. This change also covers a case when multiple HPAs
  point to the same deployment.'
   ([#112011](https://github.com/kubernetes/kubernetes/pull/112011), [@pbeschetnov](https://github.com/pbeschetnov))

  // +optional
  optional StorageOSVolumeSource storageos = 27;

  // csi (Container Storage Interface) represents ephemeral storage that is handled by certain external CSI drivers (Beta feature).
  // +optional
  optional CSIVolumeSource csi = 28;

  // ephemeral represents a volume that is handled by a cluster storage driver.