## 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)

### 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`.

- 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 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

    *   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)

## External Dependencies
* The supported etcd server version is 3.1.12, as compared to 3.1.10 in v1.9 ([#60998](https://github.com/kubernetes/kubernetes/pull/60998))
* The validated docker versions are the same as for v1.9: 1.11.2 to 1.13.1 and 17.03.x ([ref](https://github.com/kubernetes/kubernetes/blob/release-1.10/test/e2e_node/system/docker_validator_test.go))

- The resource version option, when passed to a list call, is now consistently interpreted as the minimum allowed resource version.  Previously when listing resources that had the watch cache disabled clients could retrieve a snapshot at that exact resource version.  If the client requests a resource version newer than the current state, a TimeoutError is returned suggesting the client retry in a few seconds....

## **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

- The list of validated docker versions remain unchanged at 1.11.1, 1.12.1, 1.13.1, 17.03, 17.06, 17.09, 18.06 since Kubernetes 1.12. ([#68495](https://github.com/kubernetes/kubernetes/pull/68495))
- The default Go version was updated to 1.11.2. ([#70665](https://github.com/kubernetes/kubernetes/pull/70665))
- The minimum supported Go version was updated to 1.11.2 ([#69386](https://github.com/kubernetes/kubernetes/pull/69386))

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.