*   The API group/version for the kube-proxy configuration has changed from `componentconfig/v1alpha1` to `kubeproxy.config.k8s.io/v1alpha1`. If you are using a config file for kube-proxy instead of the command line flags, you must change its apiVersion to `kubeproxy.config.k8s.io/v1alpha1`. ([#53645](https://github.com/kubernetes/kubernetes/pull/53645), [@xiangpengzhao](https://github.com/xiangpengzhao))

- '`kube-apiserver`: adds `--authentication-config` flag for reading `AuthenticationConfiguration`
  files. `--authentication-config` flag is mutually exclusive with the existing `--oidc-*`
  flags.' ([#119142](https://github.com/kubernetes/kubernetes/pull/119142), [@aramase](https://github.com/aramase))
- '`kube-scheduler` component config (`KubeSchedulerConfiguration`) `kubescheduler.config.k8s.io/v1beta3`

- Kubeadm: Allow manually upgraded component configs to be supplied in a YAML file via the --config option during upgrade plan & apply. The old behavior of --config in which kubeadm configuration and component configs that overwrite...

  * No longer updates the last-applied-configuration annotation when --save-config is unspecified or false. ([#41924](https://github.com/kubernetes/kubernetes/pull/41924), [@ymqytw](https://github.com/ymqytw))
  * Fixes issue that caused apply to revert changes made by edit

#### Bug fixes

* Change default clusterCIDRs from /16 to /14 in GCE configs allowing 1000 Node clusters by default. ([#25350](https://github.com/kubernetes/kubernetes/pull/25350), [@gmarek](https://github.com/gmarek))

    * Added --config-map and --config-map-namespace command line options.
    * If --config-map is set, kube-dns will load dynamic configuration from the config map
      referenced by --config-map-namespace, --config-map. The config-map supports
      the following properties: "federations".
    * --federations flag is now deprecated. Prefer to set federations via the config-map.

- Kubeadm:  'kubeadm alpha kubelet config download' has been removed, please use 'kubeadm upgrade node phase kubelet-config' instead ([#87944](https://github.com/kubernetes/kubernetes/pull/87944), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]

   * -viper-config can be used to set also the options defined by command line flags
   * the default config file is "e2e.yaml/toml/json/..." and the test starts when no such config is found (as before) but if -viper-config is used, the config file must exist
   * -viper-config can be used to select a file with full path, with or without file suffix

- kubeadm: Default component configs are now printable via kubeadm config print-default ([#66074](https://github.com/kubernetes/kubernetes/pull/66074), [@rosti](https://github.com/rosti)) Courtesy of SIG Cluster Lifecycle

- Add flag --lease-max-object-size and metric etcd_lease_object_counts for kube-apiserver to config and observe max objects attached to a single etcd lease. ([#97480](https://github.com/kubernetes/kubernetes/pull/97480), [@lingsamuel](https://github.com/lingsamuel)) [SIG API Machinery, Instrumentation and Scalability]