- To address the possibility of dry-run requests overwhelming admission webhooks...

HorizontalPodAutoscaler added a `spec.behavior` field that allows scale behavior to be configured. Behaviors are specified separately for scaling up and down. In each direction a stabilization window can be specified as well as a list of policies and how to select amongst them. Policies can limit the absolute number of pods added or removed, or the percentage of pods added or removed. ([#74525](https://github.com/kubernetes/kubernetes/pull/74525), [@gliush](https://github.com/gliush)) [SIG API Machinery, Apps,...

automatically provision a PersistentVolume to bind to an unfulfilled
PersistentVolumeClaim.
  * Run multiple schedulers in parallel, e.g. one or more custom schedulers
alongside the default Kubernetes scheduler, using pod annotations to select
among the schedulers for each pod. Documentation is [here](http://kubernetes.io/docs/admin/multiple-schedulers.md), design doc is [here](docs/proposals/multiple-schedulers.md).

* If the cluster node count exceeds the GCE TargetPool maximum (currently 1000), ([#25178](https://github.com/kubernetes/kubernetes/pull/25178), [@zmerlynn](https://github.com/zmerlynn))
    * randomly select which nodes are members of Kubernetes External Load Balancers.

   ([#109525](https://github.com/kubernetes/kubernetes/pull/109525), [@jonyhy96](https://github.com/jonyhy96))

### 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.'

* "kubectl wait" command now supports the "--all" flag to select all resources in the namespace of the specified resource types. ([#70599](https://github.com/kubernetes/kubernetes/pull/70599), [@caesarxuchao](https://github.com/caesarxuchao))

- `kubectl exec` now allows using the resource name to select a matching pod and `--pod-running-timeout` flag to wait till at least one pod is running. ([#73664](https://github.com/kubernetes/kubernetes/pull/73664), [@prksu](https://github.com/prksu))

* kubectl port-forward now allows using resource name (e.g., deployment/www) to select a matching pod, as well as the use of --pod-running-timeout to wait until at least one pod is running. ([#59705](https://github.com/kubernetes/kubernetes/pull/59705), [@phsiao](https://github.com/phsiao))

*   The RBAC bootstrapping policy now allows authenticated users to create selfsubjectrulesreviews. ([#56095](https://github.com/kubernetes/kubernetes/pull/56095),[ @ericchiang](https://github.com/ericchiang))
*   RBAC ClusterRoles can now select other roles to aggregate. ([#54005](https://github.com/kubernetes/kubernetes/pull/54005),[ @deads2k](https://github.com/deads2k))

   * the default config file is "e2e.yaml/toml/json/..." and the test starts when no such config is found (as before) but if -viper-config is used, the config file must exist
   * -viper-config can be used to select a file with full path, with or without file suffix
   * the csiImageVersion/Registry flags were renamed to storage.csi.imageVersion/Registry