- Kubectl: The deprecated `kubectl alpha debug` command is removed. Use `kubectl debug` instead. ([#98111](https://github.com/kubernetes/kubernetes/pull/98111), [@pandaamanda](https://github.com/pandaamanda)) [SIG CLI]

        * Switch to basing our image of Elasticsearch in fluentd-elasticsearch addon off the official one
        * Switch to the official image of Kibana in fluentd-elasticsearch addon
        * Use StatefulSet for Elasticsearch instead of ReplicationController, with persistent volume claims

### Network

*   Added a new --etcd-upgrade keyword to kubeadm upgrade apply. When this keyword is specified, etcd's static pod gets upgraded to the etcd version officially recommended for a target kubernetes release. ([#55010](https://github.com/kubernetes/kubernetes/pull/55010),[ @sbezverk](https://github.com/sbezverk))

* kubectl built for darwin from darwin now enables cgo to use the system-native C libraries for DNS resolution. Cross-compiled kubectl (e.g. from an official kubernetes release) still uses the go-native netgo DNS implementation.  ([#64219](https://github.com/kubernetes/kubernetes/pull/64219), [@ixdy](https://github.com/ixdy))

- `kubeadm init` and `kubeadm init phase` now have a `--image-repository` flag, improving support for environments with limited access to official kubernetes repository.
- The DynamicKubeletConfig and SelfHosting functionality was moved outside of `kubeadm init` and feature gates and is now exposed under `kubeadm alpha`.

- The `NetworkPolicyLegacy` test suite (deprecated in `v1.21`) has now officially been removed in favor of the new table driven e2e tests. ([#118915](https://github.com/kubernetes/kubernetes/pull/118915), [@astoycos](https://github.com/astoycos))

* duplicate kube-apiserver to federated-apiserver ([#23509](https://github.com/kubernetes/kubernetes/pull/23509), [@jianhuiz](https://github.com/jianhuiz))
* Kubelet: Start using the official docker engine-api ([#23506](https://github.com/kubernetes/kubernetes/pull/23506), [@Random-Liu](https://github.com/Random-Liu))

### Action required

  * Docker v1.9.1 is officially recommended. Docker v1.8.3 and Docker v1.10 are
supported. If you are using an older release of Docker, please upgrade. Known
issues with Docker 1.9.1 can be found below.

- Added network stats for Windows nodes and pods. ([#70121](https://github.com/kubernetes/kubernetes/pull/70121), [@feiskyer](https://github.com/feiskyer))