- JWT authenticator config set via the --authentication-config flag is now dynamically reloaded as the file changes on disk. ([#123525](https://github.com/kubernetes/kubernetes/pull/123525), [@enj](https://github.com/enj)) [SIG API Machinery, Auth and Testing]

- `kubeadm`: added a new "kubeadm config validate" command that can be used to
  validate any input config file. Use the `--config` flag to pass a config file
  to it. See the command `--help` screen for more information. As a result of adding
  this new command, enhance the validation capabilities of the existing "kubeadm

* kubeadm: remove deprecated kubeadm config print-defaults command ([#71467](https://github.com/kuberne...

- kubelet: the `--image-credential-provider-config` file was loaded with strict deserialization, which failed if the config file contained duplicate or unknown fields. This protected against accidentally running with malformed config files, unindented files, or typos in field names, and it...

* kube-apiserver: The `AdmissionConfiguration` type accepted by `--admission-control-config-file` has been promoted to `apiserver.config.k8s.io/v1` with no schema changes. ([#85098](https...

*   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:  '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-config Before:

```
apiVersion: v1
kind: ConfigMap
metadata:
  name: kubeadm-config
data:
  MasterConfiguration: |
    kubeProxy:
      config:
        featureGates: "SupportIPVSProxyMode=true"
```