- `kubectl run` has removed the previously deprecated generators, along...

#### Multicluster

Various controllers read from multiple clusters.

This is rooted in the Multicluster Secret controller, which reads `kubeconfig` files (stored as `Secrets`), and creating Kubernetes clients for each. The controller allows registering handlers which can process Add/Update/Delete of clusters.

This has two implementations:

* You can now use `kubeadm token` specifying `--kubeconfig`.  In this case, kubeadm searches the current user home path and the environment variable KUBECONFIG for existing files. If provided, the `--kubeconfig` flag will be honored instead. ([#62850](https://github.com/kubernetes/kubernetes/pull/62850), [@neolit123](https://github.com/neolit123))

- Kubeadm: add the "--cluster-name" flag to the "kubeadm alpha kubeconfig user" to allow configuring the cluster name in the generated kubeconfig file ([#93992](https://github.com/kubernetes/kubernetes/pull/93992), [@prabhu43](https://github.com/prabhu43)) [SIG Cluster Lifecycle]

* New federation deployment mechanism now allows non-GCP clusters. ([#34620](https://github.com/kubernetes/kubernetes/pull/34620), [@madhusudancs](https://github.com/madhusudancs))
  * Writes the federation kubeconfig to the local kubeconfig file.
* Update the series and the README to reflect the change. ([#30374](https://github.com/kubernetes/kubernetes/pull/30374), [@mbruzek](https://github.com/mbruzek))

* kubeadm: fix a bug where standard kubeconfig paths were searched even if the user provided /etc/kubernetes/admin.conf explicitly for commands that accept --kubeconfig, like kubeadm token. ([#71874](https://github.com/kubernetes/kubernetes/pull/71874), [@neolit123](https://github.com/neolit123))
    * kubeadm: use the default kubeconfig (/etc/kubernetes/admin.conf) for "kubeadm reset" and "kubeadm upgrade" commands.

running in. ([#44862](https://github.com/kubernetes/kubernetes/pull/44862), [@liggitt](https://github.com/liggitt))

    * Kubectl commands run inside a pod using a kubeconfig file now use the namespace specified in the kubeconfig file, instead of using the pod namespace. If no kubeconfig file is used, or the kubeconfig does not specify a namespace, the pod namespace is still used as a fallback. ([#44570](https://github.com/kubernetes/kubernetes/pull/44570), [@liggitt](https://github.com/liggitt))...

  - `--port`
  - `--address`
  The insecure port flags `--port` may only be set to 0 now.
  
  In addtion, please be careful that:
  - controller-manager MUST start with `--authorization-kubeconfig` and `--authentication-kubeconfig` correctly set to get authentication/authorization working.
  - liveness/readiness probes to controller-manager MUST use HTTPS now, and the default port has been changed to 10257.

- Kubeadm: relax the validation of kubeconfig server URLs. Allow the user to define custom kubeconfig server URLs without erroring out during validation of existing kubeconfig files (e.g. when using external CA mode). ([#94816](https://github.com/kubernetes/kubernetes/pull/94816), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

* Bump minimum API version for docker to 1.21 ([#27208](https://github.com/kubernetes/kubernetes/pull/27208), [@yujuhong](https://github.com/yujuhong))
* Adding lock files for kubeconfig updating ([#28034](https://github.com/kubernetes/kubernetes/pull/28034), [@krousey](https://github.com/krousey))