- `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

## 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)

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.

- `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...

- The go version defined in `.go-version` is now fetched when invoking test, build, and code generation targets if the current go version does not match it. Set $FORCE_HOST_GO=y while testing or building to skip this behavior, or set $GO_VERSION to override the selected go version. ([#115498](https://github.com/kubernetes/kubernetes/pull/115498), [@liggitt](https://github.com/liggitt)) [SIG Release...

Roughly **all the docs** have been rewritten to use `Annotated` as the main way to declare **parameters** and **dependencies**. All the **examples** in the docs now include a version with `Annotated` and a version without it, for each of the specific Python versions (when there are small differences/improvements in more recent versions). There were around 23K new lines added between docs, examples, and tests. 🚀

The key updated docs are:

* Python Types Intro:

- The go version defined in `.go-version` is now fetched when invoking test, build, and code generation targets if the current go version does not match it. Set $FORCE_HOST_GO=y while testing or building to skip this behavior, or set $GO_VERSION to override the selected go version. ([#115497](https://github.com/kubernetes/kubernetes/pull/115497), [@liggitt](https://github.com/liggitt)) [SIG Release...

    *   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)

- `kubectl api-resources` now prints the API version (as 'API group/version', same as output of `kubectl api-versions`). The column APIGROUP is now APIVERSION ([#95253](https://github.com/kubernetes/kubernetes/pull/95253), [@sallyom](https://github.com/sallyom)) [SIG CLI]

### 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`.