- Kubeadm: added the experimental (alpha) feature gate `EtcdLearnerMode` that allows etcd members to be joined as learner and only then promoted as voting members ([#113318](https://github.com/kubernetes/kubernetes/pull/113318), [@pacoxu](https://github.com/pacoxu))

[Setup topics]: https://kubernetes.io/docs/setup/pick-right-solution/
[SIGs]: https://github.com/kubernetes/community/blob/master/sig-list.md


## Major Themes

Kubernetes is developed by community members whose work is organized into
[Special Interest Groups][]. For the 1.8 release, each SIG provides the
themes that guided their work.

- 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. ([#117724](https://github.com/kubernetes/kubernetes/pull/117724), [@dlipovetsky](https://github.com/dlipovetsky))...

- `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))

- 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. ([#117916](https://github.com/kubernetes/kubernetes/pull/117916), [@dlipovetsky](https://github.com/dlipovetsky))...