* Add automatic etcd 3.2->3.1 and 3.1->3.0 minor version rollback support to gcr.io/google_container/etcd images. For HA clusters, all members must be stopped before performing a rollback. ([#59298](https://github.com/kubernetes/kubernetes/pull/59298), [@jpbetz](https://github.com/jpbetz))

* fixes a memory leak in the kube-controller-manager observed when large numbers of pods with tolerations are created/deleted ([#65339](https://github.com/kubernetes/kubernetes/pull/65339), [@liggitt](https://github.com/liggitt))

- Kubeadm: fix a bug where "kubeadm join" would not properly handle missing names for existing etcd members. ([#97372](https://github.com/kubernetes/kubernetes/pull/97372), [@ihgann](https://github.com/ihgann)) [SIG Cluster Lifecycle]

- Moved fluentd-elasticsearch addon images to community controlled location ([#73819](https://github.com/kubernetes/kubernetes/pull/73819), [@coffeepac](https://github.com/coffeepac))
- Removed local etcd members from the etcd cluster when `kubeadm reset` ([#74112](https://github.com/kubernetes/kubernetes/pull/74112), [@pytimer](https://github.com/pytimer))

- If `kubeadm reset` finds no etcd member ID for the peer it removes during the `remove-etcd-member` phase, it continues immediately to other phases, instead of retrying the phase for up to 3 minutes before continuing. ([#118192](https://github.com/kubernetes/kubernetes/pull/118192), [@dlipovetsky](https://github.com/dlipovetsky))...

- Kubeadm: add the flag "--experimental-initial-corrupt-check" to etcd static Pod manifests to ensure etcd member data consistency ([#109076](https://github.com/kubernetes/kubernetes/pull/109076), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

## Dependencies

### Added
_Nothing has changed._

- Kubeadm: add the flag "--experimental-initial-corrupt-check" to etcd static Pod manifests to ensure etcd member data consistency ([#109075](https://github.com/kubernetes/kubernetes/pull/109075), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

## Dependencies

### Added
_Nothing has changed._

## Changelog since v1.15.0

### Other notable changes

* kubeadm: implement support for concurrent add/remove of stacked etcd members ([#79677](https://github.com/kubernetes/kubernetes/pull/79677), [@neolit123](https://github.com/neolit123))

- `kubeadm`: promoted feature gate `EtcdLearnerMode` to `beta`. Learner mode for
  joining `etcd` members is now enabled by default. ([#120228](https://github.com/kubernetes/kubernetes/pull/120228), [@pacoxu](https://github.com/pacoxu))

### SIG-ibmcloud

As a newly created SIG, the SIG-ibmcloud has mainly focused on SIG set up, sharing IBM Clouds ongoing Kubernetes work like scalability tests, Kubernetes upgrade strategy etc. with the SIG members and start working on processes to move cloud provider code to a public GitHub repo.

### SIG-instrumentation

No feature work, but a large refactoring of metrics-server as well as a number of bug fixes.