- Kubeadm: updated the supported etcd version to v3.5.23 for supported control plane versions v1.31, v1.32, and v1.33. ([#134692](https://github.com/kubernetes/kubernetes/pull/134692), [@joshjms](https://github.com/joshjms)) [SIG Cluster Lifecycle and Etcd]

## External Dependencies

* Default etcd server version is v3.2.18 compared with v3.1.12 in v1.10 ([#61198](https://github.com/kubernetes/kubernetes/pull/61198))
* Rescheduler is v0.4.0, compared with v0.3.1 in v1.10 ([#65454](https://github.com/kubernetes/kubernetes/pull/65454))
* The validated docker versions are the same as for v1.10: 1.11.2 to 1.13.1 and 17.03.x (ref)

## External Dependency Version Information

Continuous integration builds have used the following versions of external dependencies, however, this is not a strong recommendation and users should consult an appropriate installation or upgrade guide before deciding what versions of etcd, docker or rkt to use.

* Docker versions 1.10.3, 1.11.2, 1.12.6 have been validated
  * Docker version 1.12.6 known issues

  - `spec.version` is removed in v1; use `spec.versions` instead
  - `spec.validation` is removed in v1; use `spec.versions[*].schema` instead
  - `spec.subresources` is removed in v1; use `spec.versions[*].subresources` instead
  - `spec.additionalPrinterColumns` is removed in v1; use `spec.versions[*].additionalPrinterColumns` instead

- `kubeadm`: will now allow deploying a kubelet that is 3 versions older than the version of `kubeadm` (N-3). This aligns with the recent change made by SIG Architecture that extends the support skew between the control plane and kubelets. Tolerate this new kubelet skew for the commands `init`, `join` and `upgrade`. Note that if the `kubeadm` user applies a control plane version that is older than the `kubeadm` version (N-1 maximum) then the skew between the kubelet and control plane would...

For stable features, the `kubectl` tool follows the Kubernetes [version skew policy](https://kubernetes.io/releases/version-skew-policy/);
however, kubectl v1.21 and older do not support the new API for ephemeral containers.

  when the kernel version was 4.15 or higher. With the kernel 4.15 the sysctl became namespaced.
  Pod Security admission allowed these sysctl in v1.32+ versions of the baseline and restricted policies. ([#127489](https://github.com/kubernetes/kubernetes/pull/127489), [@pacoxu](https://github.com/pacoxu)) [SIG Auth, Network and Node]

    *   You can manually set `--cloud-provider=auto-detect`, but be aware that this behavior will be removed completely in a future version.
    *   Best practice for version 1.9 and future versions is to explicitly set a cloud-provider. See [the documentation](https://kubernetes.io/docs/getting-started-guides/scratch/#cloud-providers)

### Autoscaling

 - Consuming metrics directly from Heapster is deprecated in favor of
   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`.

    - [Am I vulnerable?](#am-i-vulnerable)
      - [Affected Versions](#affected-versions)
    - [How do I mitigate this vulnerability?](#how-do-i-mitigate-this-vulnerability)
      - [Fixed Versions](#fixed-versions)
    - [Detection](#detection)
      - [Additional Details](#additional-details)
      - [Acknowledgements](#acknowledgements)