possibility of dry-run requests overwhelming admission webhooks that rely on side effects and a reconciliation mechanism, a new field is being added to `admissionregistration.k8s.io/v1beta1.ValidatingWebhookConfiguration` and `admissionregistration.k8s.io/v1beta1.MutatingWebhookConfiguration` so that webhooks can explicitly register as having dry-run support. If a dry-run request is made on a resource that triggers a non dry-run supporting webhook, the request will be completely rejected, with "400:...

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---
apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingWebhookConfiguration
metadata:
  creationTimestamp: null
  name: metallb-webhook-configuration
webhooks:
- admissionReviewVersions:
  - v1
  clientConfig:
    service:
      name: webhook-service
      namespace: metallb-system
      path: /validate-metallb-io-v1beta2-bgppeer
  failurePolicy: Fail

* Add mechanism for Admission Webhooks to specify which version of AdmissionReview they support ([#74998](https://github.com/kubernetes/kubernetes/pull/74998), [@mbohlool](https://github.com/mbohlool))
    * Add mechanism for CRD Conversion Webhooks to specify which version of ConversionReview they support

#tokenreview-v1-authentication-k8s-io) for the new tokens for improved scoping. Under audit logging, the new alpha-level "dynamic audit configuration" adds support for [dynamically registering webhooks to receive a stream of audit events](https://kubernetes.io/docs/tasks/debug/debug-cluster/audit/#webhook-backend). Finally, we've enhanced secrets protection by graduating [etcd encryption](https://kubernetes.io/docs/tasks/administer-cluster/encrypt-data/) out of experimental.

### SIG...

Kubernetes 1.19 / go 1.15. Serving certificates used by admission webhooks, custom resource conversion webhooks, and aggregated API servers must now include valid Subject Alternative Names. If you are running Kubernetes 1.22 with `GODEBUG=x509ignoreCN=0` set, check the `apiserver_kube_aggregator_x509_missing_san_total` and `apiserver_webhooks_x509_missing_san_total` metrics for non-zero values to see if the API server is connecting to webhooks or aggregated API servers using certificates that will be considered...

			return nil, fmt.Errorf("unable to initialize the queue store of Webhook `%s`: %w", id, err)
		}
	}

	target := &WebhookTarget{
		id:         event.TargetID{ID: id, Name: "webhook"},
		args:       args,
		loggerOnce: loggerOnce,
		transport:  transport,
		store:      queueStore,
		cancel:     cancel,
		cancelCh:   ctx.Done(),
	}

	// Calculate the webhook addr with the port number format

	}

	return nil
}

// NewWebhookTarget - creates new Webhook target.
func NewWebhookTarget(ctx context.Context, id string, args WebhookArgs, loggerOnce logger.LogOnce, transport *http.Transport) (*WebhookTarget, error) {
	ctx, cancel := context.WithCancel(ctx)

	target := &WebhookTarget{
		id:         event.TargetID{ID: id, Name: "webhook"},
		args:       args,
		loggerOnce: loggerOnce,
		transport:  transport,

- Kube-apiserver: Authorization webhooks now report the following metrics:
  - apiserver_authorization_webhook_evaluations_total
  - apiserver_authorization_webhook_duration_seconds

- Fixed an issue where the API server did not send impersonated UID to authentication webhooks. ([#116681](https://github.com/kubernetes/kubernetes/pull/116681), [@stlaz](https://github.com/stlaz)) [SIG API Machinery and Auth]