* Bump GCE ContainerVM to container-vm-v20170201 to address CVE-2016-9962. ([#40828](https://github.com/kubernetes/kubernetes/pull/40828), [@zmerlynn](https://github.com/zmerlynn))
* Adding vmdk file extension for vmDiskPath in vsphere DeleteVolume ([#40538](https://github.com/kubernetes/kubernetes/pull/40538), [@divyenpatel](https://github.com/divyenpatel))

### Container Images

All container images are available as manifest lists and support the described
architectures. It is also possible to pull a specific architecture directly by
adding the "-$ARCH" suffix  to the container image name.
name | architectures
---- | -------------

### ConfigMap
* Volumes and environment variables populated from ConfigMap and Secret objects can now tolerate the named source object or specific keys being missing, by adding `optional: true` to the volume or environment variable source specifications. ([#39981](https://github.com/kubernetes/kubernetes/pull/39981), [@fraenkel](https://github.com/fraenkel))

    - kubeadm: implemented CRI detection for Windows worker nodes ([#78053](https://github.com/kubernetes/kubernetes/pull/78053), [@ksubrmnn](https://github.com/ksubrmnn))
- Worked toward support for Windows Server version 1903, including adding Windows support for preserving the destination IP as the VIP when loadbalancing with DSR. ([#74825](https://github.com/kubernetes/kubernetes/pull/74825), [@ksubrmnn](https://github.com/ksubrmnn))

  * **alpha**: NVIDIA GPU support ([#24836](https://github.com/kubernetes/kubernetes/pull/24836), [@therc](https://github.com/therc))
  * Adding loadBalancer services and nodeports services to quota system

## Known Issues and Important Steps before Upgrading

- `kube-apiserver` added:

### Container Images

All container images are available as manifest lists and support the described
architectures. It is also possible to pull a specific architecture directly by
adding the "-$ARCH" suffix  to the container image name.

name | architectures
---- | -------------

	* Mechanism of adding `federation domain maps` to kube-dns deployment via `--federations` flag is superseded by adding/updating `federations` key in `kube-system/kube-dns` configmap. If user is using kubefed tool to join cluster federation, adding federation domain maps to kube-dns is already taken care by `kubefed join` and does not need further action.

kube-apiserver (instead of --etcd-config):
     * --etcd-certfile, --etcd-keyfile (if using client cert auth)
     * --etcd-cafile (if not using system roots)
  * As part of preparation in 1.2 for adding support for protocol buffers (and the
direct YAML support in the API available today), the Content-Type and Accept
headers are now properly handled as per the HTTP spec.  As a consequence, if

Updated Plugin Mechanism for kubectl is Graduating to Stable ([#579](https://github.com/kubernetes/enhancements/issues/579))

- Extends functionality to kubectl to support extensions adding new commands as well as overriding specific subcommands (at any depth).
- Documentation fixes