* Skip multi-zone e2e tests unless provider is GCE, GKE or AWS ([#27871](https://github.com/kubernetes/kubernetes/pull/27871), [@lukaszo](https://github.com/lukaszo))
* Making DHCP_OPTION_SET_ID creation optional ([#27278](https://github.com/kubernetes/kubernetes/pull/27278), [@activars](https://github.com/activars))

### SIG Auth

Work this cycle focused on graduating existing functions, and on making security functions more understandable for users.

- Filter published OpenAPI schema by making nullable, required fields non-required in order to avoid kubectl to wrongly reject null values. ([#85722](https://github.com/kubernetes/kubernetes/pull/85722), [@sttts](https://github.com/sttts))

    final Stopwatch stopwatch = Stopwatch.createUnstarted();

    public LoadingValueReference() {
      this(LocalCache.<K, V>unset());
    }

    /*
     * TODO(cpovirk): Consider making this implementation closer to the mainline implementation.
     * (The difference was introduced as part of Java-8-specific changes in cl/132882204, but we

	response, err = s.client.Do(request)
	c.Assert(err, nil)
	// assert the status code of the response.
	c.Assert(response.StatusCode, http.StatusOK)

	// constructing http request to delete the bucket.
	// making an attempt to delete an non-empty bucket.
	// expected to fail.
	request, err = newTestSignedRequest(http.MethodDelete, getDeleteBucketURL(s.endPoint, bucketName),
		0, nil, s.accessKey, s.secretKey, s.signer)

- Renames the timeout field for the DelegatingAuthenticationOptions to TokenRequestTimeout and set the timeout only for the token review client. Previously the timeout was also applied to watches making them reconnecting every 10 seconds. ([#101103](https://github.com/kubernetes/kubernetes/pull/101103), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery, Auth and Cloud Provider]

  startup/readiness/liveness probe capabilities. Lifecycle handlers configured
  with `scheme: HTTPS` that encounter errors indicating the endpoint is actually
  using HTTP fall back to making the request over HTTP for compatibility with
  previous releases. When this happens, a `LifecycleHTTPFallback` event is recorded
  in the namespace of the pod and a `kubelet_lifecycle_handler_http_fallbacks_total`

- Fixed a bug which the scheduler didn't correctly tell plugins Node deletion.

- Kubeadm: remove the `--port` flag from the manifest for the `kube-controller-manager` since the flag has...

With CSI the Kubernetes volume layer becomes truly extensible, allowing third party storage developers to write drivers making their storage systems available in Kubernetes without having to touch the core code.

CSI was first introduction as alpha in Kubernetes v1.9 and moved to beta in Kubernetes v1.10.