* kubectl port-forward now allows using resource name (e.g., deployment/www) to select a matching pod, as well as the use of --pod-running-timeout to wait until at least one pod is running. ([#59705](https://github.com/kubernetes/kubernetes/pull/59705), [@phsiao](https://github.com/phsiao))

#### New Deprecations

* As a reminder, etcd2 as a backend is deprecated and support will be removed in Kubernetes 1.13. Please ensure that your clusters are upgraded to etcd3 as soon as possible.

	T2 [10]struct{ f T2 }     // T2 contains T2 as component of a struct
	T3 [10]T4                 // T3 contains T3 as component of a struct in T4
	T4 struct{ f T3 }         // T4 contains T4 as component of array T3 in a struct
)

// valid array types
type (
	T5 [10]*T5                // T5 contains T5 as component of a pointer
	T6 [10]func() T6          // T6 contains T6 as component of a function type

  `hostAliases` fields to mark the fields used as keys in those lists as either defaulted
  or required. ([#124553](https://github.com/kubernetes/kubernetes/pull/124553), [@pmalek](https://github.com/pmalek))

- SourcesReady provides the readiness of kubelet configuration sources such as apiserver update readiness. ([#81344](https://github.com/kubernetes/kubernetes/pull/81344), [@zouyee](https://github.com/zouyee))

Cluster Lifecycle

SIG Cluster Lifecycle has been focusing on improving kubeadm in order to bring it to GA in a future release, as well as developing the [Cluster API](https://github.com/kubernetes/kube-deploy/tree/master/cluster-api). For kubeadm, most new features, such as support for CoreDNS, IPv6 and Dynamic Kubelet Configuration, have gone in as alpha features. We expect to graduate these features to beta and beyond in the next release. The initial Cluster API spec and GCE sample implementation...

* Requests with the query parameter `?watch=` are treated by the API server as a request to watch, but authorization and metrics were not correctly identifying those as watch requests, instead grouping them as list calls. ([#48583](https://github.com/kubernetes/kubernetes/pull/48583), [@smarterclayton](https://github.com/smarterclayton))

### CSI Health Monitoring

The CSI health monitoring feature is being released as a second Alpha in Kubernetes 1.21. This feature enables CSI Drivers to share abnormal volume conditions from the underlying storage systems with Kubernetes so that they can be reported as events on PVCs or Pods. This feature serves as a stepping stone towards programmatic detection and resolution of individual volume health issues by Kubernetes.

  * Caveat: The alpha version no longer supports, and...

- Enable external plugins can be used as subcommands for kubectl create command if subcommand does not exist as builtin only when KUBECTL_ENABLE_CMD_SHADOW environment variable is exported. ([#116293](https://github.com/kubernetes/kubernetes/pull/116293), [@ardaguclu](https://github.com/ardaguclu))