for the kubelet in the dropin, a structured configuration file for the kubelet is used, and is expected to be present in `/var/lib/kubelet/config.yaml`. For runtime-detected, instance-specific configuration values, a environment file with dynamically-generated flags at `kubeadm init` or `kubeadm join` run time is used. Finally, if you want to override something specific for the kubelet that can't be done via the kubeadm Configuration file (which is preferred), you might add flags to the `KUBELET_EXTRA_ARGS`...

### Other notable changes

* Kubernetes json deserializer is now case-sensitive to restore compatibility with pre-1.8 servers. ([#65157](https://github.com/kubernetes/kubernetes/pull/65157), [@caesarxuchao](https://github.com/caesarxuchao))
    * If your config files contains fields with wrong case, the config files will be now invalid.

- kube-proxy: a configuration file specified via `--config` is now loaded with strict deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. ([#82927](https://github.com/kubernetes/kubernetes/pull/82927),...

 
#### Configuration file changes:

#### kube-apiserver:

* Pre-existing log files are now opened with O_APPEND, instead of O_TRUNC. This helps prevent losing logs when components crash-loop, and also enables external log rotation utilities to truncate log files in-place without components extending log files to their pre-truncation sizes on subsequent writes. ([#74837](https://github.com/kubernetes/kubernetes/pull/74837), [@mtaufen](https:...

   * -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
   * the csiImageVersion/Registry flags were renamed to storage.csi.imageVersion/Registry

*   Relative paths in the Kubelet's local config files (`--init-config-dir`) will now be resolved relative to the location of the containing files. ([#55648](https://github.com/kubernetes/kubernetes/pull/55648),[ @mtaufen](https://github.com/mtaufen))

- 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 prevented unexpected behavior. ([#128062](https://github.com/kubernetes/kubernetes/pull/128062), [@aramase](https:...

- Kube-apiserver: the `--encryption-provider-config` file is now loaded with strict deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. When `--encryption-provider-config-automatic-reload` is used, new encryption config files that contain typos after the kube-apiserver is running are treated as...

all` or just `kubeadm init` will now generate the new `super-admin.conf` file. The cluster admin can then decide to keep the file present on a node host or move it to a safe location. `kubadm certs renew` will renew the certificate in `super-admin.conf` to one year if the file exists; if it does not exist a "MISSING" note will be printed. `kubeadm upgrade apply` for this release will migrate this particular node to the two file setup. Subsequent kubeadm releases will continue to optionally renew the...