Niranjan Hasabnis, P-Hidringer, Paul Van Eck, Peng Yu, Qing Zhao, Qingying Chen,
Quanlong, Rajendra Arora, Rholais Lii, rmanyari, Robin Richtsfeld, Russell
Klopfer, Sagi, Sam Sendelbach, Sandeep N Gupta, Sandip Giri, Sarah Edkins, Scott
Tseng, Sdalbsoo, Sergii Khomenko, Seungwoo Choi (Biggie), Seyed Majid Azimi,
Shaoning Zeng, shengfuintel, Siu Kei, Muk, Smit Shilu, soonson, Stefan Schweter,

- Add "reason" field to image_garbage_collected_total metric, so admins can differentiate images that were collected for reason "age" vs "space" ([#123345](https://github.com/kubernetes/kubernetes/pull/123345), [@haircommander](https://github.com/haircommander)) [SIG Node]

* Improves performance of Cinder volume attach/detach operations ([#41785](https://github.com/kubernetes/kubernetes/pull/41785), [@jamiehannaford](https://github.com/jamiehannaford))
* GCE and AWS dynamic provisioners extension: admins can configure zone(s) in which a persistent volume shall be created. ([#38505](https://github.com/kubernetes/kubernetes/pull/38505), [@pospispa](https://github.com/pospispa))

 - `kubeadm`: a separate "super-admin.conf" file is now deployed. The User in `admin.conf` is now bound to a new RBAC Group `kubeadm:cluster-admins` that has `cluster-admin` `ClusterRole` access. The User in `super-admin.conf` is now bound to the `system:masters` built-in super-powers / break-glass Group that can bypass RBAC. Before this change, the default `admin.conf` was bound to `system:masters`...