- Added support for projected volume in describe function  ([#70158](https://github.com/kubernetes/kubernetes/pull/70158), [@WanLinghao](https://github.com/WanLinghao))
- kubeadm now automatically creates a new stacked etcd member when joining a new control plane node (does not applies to external etcd) ([#69486](https://github.com/kubernetes/kubernetes/pull/69486), [@fabriziopandini](https://github.com/fabriziopandini))

from v1beta3 and its management in the kube-system/kubeadm-config ConfigMap. This method of keeping track of what API endpoints exists in the cluster was replaced (in a prior release) by a method to annotate the etcd Pods that `kubeadm` creates in "stacked etcd" clusters. The following CLI sub-phases are deprecated and are now a NO-OP: for `kubeadm join`: "control-plane-join/update-status", for `kubeadm reset`: "update-cluster-status". Unless you are using these phases explicitly, you should not be...

- [IPv4/IPv6 dual-stack](https://kubernetes.io/docs/concepts/services-networking/dual-stack) enables the allocation of both IPv4 and IPv6 addresses to Pods and Services.

- Kube-proxy: on dual-stack mode, if it is not able to get the IP Family of an endpoint, logs it with level InfoV(4) instead of Warning, avoiding flooding the logs for endpoints without addresses ([#88934](https://github.com/kubernetes/kubernetes/pull/88934), [@aojea](https://github.com/aojea)) [SIG Network]

- Users might specify the `kubectl.kubernetes.io/default-container` annotation in a Pod to...

## Changelog since v1.15.0

### Other notable changes

* kubeadm: implement support for concurrent add/remove of stacked etcd members ([#79677](https://github.com/kubernetes/kubernetes/pull/79677), [@neolit123](https://github.com/neolit123))

### IPv4/IPv6 run

IPv4/IPv6 dual-stack has been reimplemented for 1.20 to support dual-stack Services, based on user and community feedback. If your cluster has dual-stack enabled, you can create Services which can use IPv4, IPv6, or both, and you can change this setting for existing Services. Details are available in updated [IPv4/IPv6 dual-stack docs](https://docs.k8s.io/concepts/services-networking/dual-stack/), which cover the nuanced array of options.

  // to SingleStack. Services can be "SingleStack" (a single IP family),
  // "PreferDualStack" (two IP families on dual-stack configured clusters or
  // a single IP family on single-stack clusters), or "RequireDualStack"
  // (two IP families on dual-stack configured clusters, otherwise fail). The
  // ipFamilies and clusterIPs fields depend on the value of this field. This

* **[alpha]** New Bootstrap Token authentication and management method. Works well with kubeadm. kubeadm now supports managing tokens, including time based expiration, after...

The external cloud provider was established and reached feature parity with in-tree, and we expect to stabilize it and have it as preferred deployment model by 1.13. We are also getting started on externalizing the vSphere volume functionalities in a CSI plugin to fully reproduce the current in-tree storage functionality.