- 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))

- Kubeadm now respects the custom image registry configuration across joins and upgrades. Kubeadm passes the custom registry to the kubelet for a custom pause container. ([#70603](https://github.com/kubernetes/kubernetes/pull/70603), [@chuckha](https://github.com/chuckha))

### Federation

#### kubefed
* Flag cleanup ([#41335](https://github.com/kubernetes/kubernetes/pull/41335), [@irfanurrehman](https://github.com/irfanurrehman))
* Create configmap for the cluster kube-dns when cluster joins and remove when it unjoins ([#39338](https://github.com/kubernetes/kubernetes/pull/39338), [@irfanurrehman](https://github.com/irfanurrehman))