- Kubeadm: remove the automatic detection and matching of cgroup drivers for Docker. For new clusters if you have not configured the cgroup driver explicitly you might get a failure in the `kubelet` on driver mismatch (kubeadm clusters should be using the `systemd` driver). Also remove the `IsDockerSystemdCheck` preflight check (warning) that checks if the Docker cgroup driver is set to `systemd`. Ideally such detection / coordination should be on the side of CRI...

* Add support for SourceIP preservation in Azure LBs ([#36557](https://github.com/kubernetes/kubernetes/pull/36557), [@brendandburns](https://github.com/brendandburns))
* Fix fetching pids running in a cgroup, which caused problems with OOM score adjustments & setting the /system cgroup ("misc" in the summary API). ([#36551](https://github.com/kubernetes/kubernetes/pull/36551), [@timstclair](https://github.com/timstclair))

## Highlights

* Authorization:
  * **Alpha** RBAC authorization API group
* Federation
  * federation api group is now **beta**
  * Services from all federated clusters are now registered in Cloud DNS (AWS and GCP).
* Stateful Apps:
  * **alpha** PetSets manage stateful apps

  - Ignore the new `topology.gke.io/zone` label when comparing groups
  - Add missing stable labels to template nodes
  
  ### HuaweiCloud
  - Add auto scaling group support
  - Implement node group by AS
  - Implement getting desired instance number of node group
  - Implement increasing node group size
  - Implement TemplateNodeInfo
  - Implement caching instances
  
  ### IONOS

- Fixed a bug where the kubelet ephemerally failed with `failed to initialize top level QOS containers: root container [kubepods] doesn't exist`, due to the cpuset cgroup being deleted on cgroup v2 with systemd cgroup manager.
   ([#125923](https://github.com/kubernetes/kubernetes/pull/125923), [@haircommander](https://github.com/haircommander)) [SIG Node and Testing]

- If using cgroups v2, then the cgroup aware OOM killer will be enabled for container cgroups via  `memory.oom.group` .  This causes processes within the cgroup to be treated as a unit and killed simultaneously in the event of an OOM kill on any process in the cgroup. ([#117793](https://github.com/kubernetes/kubernetes/pull/117793), [@tzneal](https://github.com/tzneal)) [SIG Apps, Node and...

* kubeadm now detects the Docker cgroup driver and starts the kubelet with the matching driver. This eliminates a common error experienced by new users in when the Docker cgroup driver is not the same as the one set for the kubelet due to different Linux distributions setting different cgroup drivers for Docker, making it hard to start the kubelet properly.

Kubelet flag `--enforce-node-allocatable` with a default value of `pods` is added which will make kubelet create a top level cgroup for all pods to enforce Node Allocatable. Optionally, `system-reserved` & `kube-reserved` values can also be specified separated by comma to enforce node allocatable on cgroups specified via `--system-reserved-cgroup` & `--kube-reserved-cgroup` respectively. Note the default value of the latter flags are "". ([#41234](https://github.com/kubernetes/kubernetes/pull/41234),...

        * Whether all containers should be non-root
        * Supplemental Groups
        * FSGroup - a special supplemental group
        * SELinux options
     * If a pod defines an FSGroup, that Pod’s system (emptyDir, secret, configMap,
etc) volumes and block-device volumes will be owned by the FSGroup, and each
container in the pod will run with the FSGroup as a supplemental group

```

* Fix fetching pids running in a cgroup, which caused problems with OOM score adjustments & setting the /system cgroup ("misc" in the summary API). ([#36614](https://github.com/kubernetes/kubernetes/pull/36614), [@timstclair](https://github.com/timstclair))