- `Kubelet` no longer creates certain legacy iptables rules by default.

* Kubernetes now supports up to 5,000 nodes via etcd v3, which is enabled by default.
* [Role-based access control (RBAC)](https://kubernetes.io//docs/admin/authorization/rbac) has graduated to beta, and defines secure default roles for control plane, node, and controller components.
* The [`kubeadm` cluster bootstrap tool](https://kubernetes.io/docs/getting-started-guides/kubeadm/) has graduated to beta. Some highlights:

- The RuntimeClass API has been added. This feature is in alpha, and the RuntimeClass feature gate must be enabled in order to use it. The RuntimeClass API resource defines different classes of runtimes that may be used to run containers in the cluster. Pods can select a RuntimeClass to use via the RuntimeClassName field. ([#67737](https://github.com/kubernetes/kubernetes/pull/67737), [@tallclair](https://github.com/tallclair))...

* CRI now defines mounting behavior. If the host path doesn't exist, the runtime should return an error. If the host path is a symlink, the runtime should follow the symlink and mount the real destination to the container. ([#61460](https://github.com/kubernetes/k...

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<!--
  Description: This xml file defines the valid mime types used by Tika.
  The mime type data within this file is based on information from various
  sources like Apache Nutch, Apache HTTP Server, the file(1) command, etc.

  Notes:

- When scaling down a ReplicaSet, delete doubled up replicas first, where a "doubled up replica" is defined as one that is on the same node as an active replica belonging to a related ReplicaSet.  ReplicaSets are considered "related" if they have a common controller (typically a Deployment). ([#80004](https://github.com/kubernetes/kubernetes/pull/80004),...

- Added support for in-place vertical scaling of Pods with sidecars (containers defined within `initContainers` where the `restartPolicy` is set to `Always`). ([#128367](https://github.com/kubernetes/kubernetes/pull/128367), [@vivzbansal](https://github.com/vivzbansal)) [SIG API Machinery, Apps, CLI, Node, Scheduling and Testing]

    Potential impacts:

controller manager binary. Additionally we added [aws-k8s-tester](https://github.com/kubernetes/test-infra/issues/9814), deployer interface for kubetest, to the test-infra repository. This plugin allowed us to integrate Prow to the 3 subprojects defined above in order to provide CI signal for all 3 features. The CI signal is visible [here](https://testgrid.k8s.io/) under SIG-AWS.

For detailed release notes on the three alpha features from SIG AWS, please refer to the following Changelogs:...

- Improved scheduler performance when no scoring plugins were defined.
   ([#122058](https://github.com/kubernetes/kubernetes/pull/122058), [@aleksandra-malinowska](https://github.com/aleksandra-malinowska))
- Improved scheduler performance when no scoring plugins were defined.