* Cluster federation servers have changed the location in etcd where federated services are stored, so existing federated services must be deleted and recreated. Before upgrading, export all federated services from the federation server and delete the services. After upgrading the cluster, recreate the federated services from the exported data....

   * specified by the given {@code builder}. The returned {@link MapMakerInternalMap} will be
   * optimized to saved memory. Since {@link MapMaker.Dummy} is a singleton, we don't need to store
   * any values at all. Because of this optimization, {@code build.getValueStrength()} must be
   * {@link Strength#STRONG}.
   *

* Use protobufs by default to communicate with apiserver (still store JSONs in etcd) ([#25738](https://github.com/kubernetes/kubernetes/pull/25738), [@wojtek-t](https://github.com/wojtek-t))

- Fixed missing delete events on informer re-lists to ensure all delete events were correctly emitted and using the latest known object state, so that all event handlers and stores always reflect the actual apiserver state as best as possible ([#115620](https://github.com/kubernetes/kubernetes/pull/115620), [@odinuge](https://github.com/odinuge))

ControllerPublishVolume/ControllerUnpublishVolume, and NodePublishVolume/NodeUnpublishVolume operations. Before this change all API calls had to fetch key/value stored in secret and use it to authenticate/authorize these operations. With this change API calls receive key/value as a input parameter so they not need to know where and how credentials were stored and fetched. Main goal was to make these API calls CO (Container Orchestrator) agnostic.  ([#60118](https://github.com/kubernetes/kubernetes/pull/60118),...

- Added a field to store CSI volume expansion secrets ([#77516](https://github.com/kubernetes/kubernetes/pull/77516), [@gnufied](https://github.com/gnufied))

[seccomp-docs]: https://kubernetes.io/docs/tutorials/clusters/seccomp/


### Production images moved to community control

As of Kuberenetes v1.19, Kubernetes container images are stored on a community-controlled storage bucket, 
located at `{asia,eu,us}.gcr.io/k8s-artifacts-prod`. The `k8s.gcr.io` vanity domain has been updated 
to this new bucket. This brings production artifacts under community control.

- The ImagePullIntent and ImagePulledRecord objects used by kubelet to store information about image pulls have been moved to the v1beta1 API version. ([#132579](https://github.com/kubernetes/kubernetes/pull/132579), [@stlaz](https://github.com/stlaz)) [SIG Auth and Node]

* Kubernetes version command line parameter in kubeadm has been updated to drop an unnecessary redirection from ci/latest.txt to ci-cross/latest.txt. Users should know exactly where the builds are stored on Google Cloud storage buckets from now on. For example for 1.9 and 1.10, users can specify ci/latest-1.9 and ci/latest-1.10 as the CI build jobs what build images correctly updates those. The CI jobs for master update the ci-cross/latest location,...

- Kubeadm: add the kubeadm specific, Alpha (disabled by default) feature gate UnversionedKubeletConfigMap. When this feature is enabled kubeadm will start using a new naming format for the ConfigMap where it stores the KubeletConfiguration structure. The old format included the Kubernetes version - "kube-system/kubelet-config-1.22", while the new format does not - "kube-system/kubelet-config". A similar formatting change is done for the related RBAC rules. The...