- Kubeadm now propagates proxy environment variables to kube-proxy ([#84559](https://github.com/kubernetes/kubernetes/pull/84559), [@yastij](https://github.com/yastij))
- Update the latest validated version of Docker to 19.03 ([#84476](https://github.com/kubernetes/kubernetes/pull/84476), [@neolit123](https://github.com/neolit123))

    You can disable CRI explicitly (`--enable-cri=false`) as a
    temporary workaround.
      * The standard `bridge` plugin have been validated to interoperate with
         the new CRI + CNI code path.
      * If you are using plugins other than `bridge`, make sure you have
        updated custom plugins to the latest version that is compatible.

    * 4. Max 20 bit for range (min network bits `<v6>/108` or <v4>/12)
    * kube-controller-manager: convert service CIDR to list `--service-cluster-ip-range=<CIDR>,<CIDR>` and make sure `IPv6DualStack` feature flag is turned on. The flag is validated as above.
    * + to use:

Continuous integration builds use Docker versions 1.11.2, 1.12.6, 1.13.1,
and 17.03.2. These versions were validated on Kubernetes 1.8. However,
consult an appropriate installation or upgrade guide before deciding what
versions of Docker to use.

- Docker 1.13.1 and 17.03.2

    - Shared PID namespace, live-restore, and overlay2 were validated.

    - **Known issues**

### SIG Storage

Google Cloud required that workloads (e.g. Deployments, DaemonSets, etc.) which used `PersistentDisk` volumes were using them in read-only mode.  This validation provided very little value at relatively host implementation cost, and will no longer be validated.  If this is a problem for a specific use-case, please set the `SkipReadOnlyValidationGCE` gate to false to re-enable the validation, and file a Kubernetes bug with details. ([#121083](https://github.com/kubernetes/kubernetes/pull/121083), [@tho...

* **Other objects**: no changes unless you explicitly request orphaning.

## Action Required Before Upgrading

- If you are using Kubernetes to manage `docker` containers, please be aware Kubernetes has been validated to work with docker 1.9.1, docker 1.11.2 (#23397), and docker 1.12.0 (#28698)

* Docker versions 1.10.3, 1.11.2, 1.12.6 have been validated

    * Docker version 1.12.6 known issues

        * overlay2 driver not fully supported

        * live-restore not fully supported

        * no shared pid namespace support

- Validated APIVersion fields of the `HorizontalPodAutoscaler` to ensure that API objects were created and functioned properly. ([#132537](https://github.com/kubernetes/kubernetes/pull/132537), [@lalitc375](https://github.com/lalitc375)) [SIG Etcd and Testing]...

[CRD Validation Expression Language](https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/2876-crd-validation-expression-language/README.mdv) is promoted to beta, which makes it possible to declare how custom resources are validated using the [Common Expression Language (CEL)](https://github.com/google/cel-spec). Please see the [validation rules](https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#validation-rules) guide.