- 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))

Vig, Sebastian Raschka, Sebastian Weiss, Sergey Kolesnikov, Sergii Khomenko,
Shahid, Shivam Kotwalia, Stuart Berg, Sumit Gouthaman, superzerg, Sven Mayer,
tetris, Ti Zhou, Tiago Freitas Pereira, Tian Jin, Tomoaki Oiki, Vaibhav Sood,
vfdev, Vivek Rane, Vladimir Moskva, wangqr, Weber Xie, Will Frey, Yan Facai
(颜发才), yanivbl6, Yaroslav Bulatov, Yixing Lao, Yong Tang, youkaichao, Yuan
(Terry) Tang, Yue Zhang, Yuxin Wu, Ziming Dong, ZxYuan, 黄璞