- For `kubeadm`: remove the ClusterStatus API 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...

- kubeadm: Improved resiliency when it comes to updating the `kubeadm-config` configmap upon new control plane joins or resets. This allows for safe multiple control plane joins and/or resets. ([#76821](https://github.com/kubernetes/kubernetes/pull/76821), [@ereslibre](https://github.com/ereslibre))

* Add density (batch pods creation latency and resource) and resource performance tests to `test-e2e-node' ([#29764](https://github.com/kubernetes/kubernetes/pull/29764), [@coufon](https://github.com/coufon))
* Allow Secret & ConfigMap keys to contain caps, dots, and underscores ([#25458](https://github.com/kubernetes/kubernetes/pull/25458), [@errm](https://github.com/errm))

feature gate to Beta and enabled the feature by default. This implies that 1) for new clusters kubeadm will start using the `kube-system/kubelet-config` naming scheme for the kubelet ConfigMap and RBAC rules, instead of the legacy `kubelet-config-x.yy` naming. 2) during upgrade, kubeadm will only write the new scheme ConfigMap and RBAC objects. To disable the feature you can pass `UnversionedKubeletConfigMap: false` in the kubeadm config for new clusters. For upgrade on existing clusters you can also override...

- [kubectl] Improved the describe output for projected volume sources to clearly indicate whether Secret and ConfigMap entries are optional. ([#129457](https://github.com/kubernetes/kubernetes/pull/129457), [@gshaibi](https://github.com/gshaibi)) [SIG CLI]

* kubelet: resolved hang/timeout issues when running large numbers of pods with unique configmap/secret references ([#74755](https://github.com/kubernetes/kubernetes/pull/74755), [@liggitt](https://github.com/liggitt))

- Kubeadm: do not upload kubelet patch configuration into `kube-system/kubelet-config` ConfigMap ([#123108](https://github.com/kubernetes/kubernetes/pull/123108), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]

- kubeadm: implement retry logic for certain ConfigMap failures when joining nodes ([#78915](https://github.com/kubernetes/kubernetes/pull/78915), [@ereslibre](https://github.com/ereslibre))

- Kubeadm: do not upload kubelet patch configuration into `kube-system/kubelet-config` ConfigMap ([#123107](https://github.com/kubernetes/kubernetes/pull/123107), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]

- Fixed file permission issues that happened during update of Secret/ConfigMap/projected volume when fsGroup is used. The problem caused a race condition where application gets intermittent permission denied error when reading files that were just updated, before the correct permissions were applied. ([#114728](https://git...