equality-based selector in 1.1).
  * Running against a secured etcd requires these flags to be passed to
kube-apiserver (instead of --etcd-config):
     * --etcd-certfile, --etcd-keyfile (if using client cert auth)
     * --etcd-cafile (if not using system roots)
  * As part of preparation in 1.2 for adding support for protocol buffers (and the

- Update etcd client side to v3.4.4 ([#89169](https://github.com/kubernetes/kubernetes/pull/89169), [@jingyih](https://github.com/jingyih)) [SIG API Machinery and Cloud Provider]
- Update etcd client side to v3.4.7 ([#89822](https://github.com/kubernetes/kubernetes/pull/89822), [@jingyih](https://github.com/jingyih)) [SIG API Machinery and Cloud Provider]

- Kubeadm: during execution of the "check expiration" command, treat the etcd CA as external if there is a missing etcd CA key file (etcd/ca.key) and perform the proper validation on certificates signed by the etcd CA. Additionally, make sure that the CA for all entries in the output table is included - for both certificates on disk and in kubeconfig files. ([#106923](https://github.com/kube...

* When performing a GET then PUT, the kube-apiserver must write the canonical representation of the object to etcd if the current value does not match. That allows external agents to migrate content in etcd from one API version to another, across different storage types, or across varying encryption levels. This fixes a bug introduced in 1.5 where we unintentionally stopped writing the newest data. ([#483...

- 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))

- Fix an error when using external etcd but storing etcd certificates in the same folder with the same name used by kubeadm for local etcd certificates; for an older version of kubeadm, the workaround is to avoid file name used by kubeadm for local etcd. ([#80867](https://github.com/kubernetes/kubernetes/pull/80867), [@fabriziopandini](https://github.com/fabriziopandini))

* etcd3: watcher logging error ([#32831](https://github.com/kubernetes/kubernetes/pull/32831), [@hongchaodeng](https://github.com/hongchaodeng))
* etcd: watcher centralize error handling ([#32907](https://github.com/kubernetes/kubernetes/pull/32907), [@hongchaodeng](https://github.com/hongchaodeng))
* etcd: stop watcher when watch channel is closed ([#33003](https://github.com/kubernetes/kubernetes/pull/33003), [@hongchaodeng](https://github.com/hongchaodeng))

* etcd version 2.2.1
  * etcd version 3.0.14 [has also been validated](https://k8s-gubernator.appspot.com/builds/kubernetes-jenkins/logs/ci-kubernetes-e2e-gce-etcd3/) but does require [specific configuration steps](https://coreos.com/blog/migrating-applications-etcd-v3.html)

## Changelog since v1.5.0-beta.3

### Other notable changes

- Kubeadm: when adding new control plane nodes with "kubeamd join", ensure that the etcd member addition is performed only if a given member URL does not already exist in the list of members. Similarly, on "kubeadm reset" only remove an etcd member if its ID exists. ([#127620](https://github.com/...

* Use protobufs by default to communicate with apiserver (still store JSONs in etcd) ([#25738](https://github.com/kubernetes/kubernetes/pull/25738), [@wojtek-t](https://github.com/wojtek-t))