and \"IfNeeded\".\n\nNever: the webhook will not be called more than once in a single admission evaluation.\n\nIfNeeded: the webhook will be called at least one additional time as part of the admission evaluation if the object being admitted is modified by other admission plugins after the initial webhook call. Webhooks that specify this option *must* be idempotent, able to process objects they previously admitted. Note: * the number of additional invocations is not guaranteed to be exactly one....

*   The admission webhook configurations API, part of the admissionregistration API, is now at v1beta1. Delete any existing webhook configurations before you upgrade, and update your configuration files...

### Beta

							Default:     "",
							Type:        []string{"string"},
							Format:      "",
						},
					},
					"webhook": {
						SchemaProps: spec.SchemaProps{

							Storage: false,
						},
					},
					Conversion: &apiextensions.CustomResourceConversion{
						Strategy: apiextensions.ConversionStrategyType("Webhook"),
						WebhookClientConfig: &apiextensions.WebhookClientConfig{
							URL: strPtr("https://example.com/webhook"),
							Service: &apiextensions.ServiceReference{
								Name:      "n",
								Namespace: "ns",
							},
						},
					},

- **Admission webhooks:** Admission webhooks are in widespread use as a Kubernetes extensibility mechanism and have been available in beta since the 1.9 release. The 1.16 release marks the graduation of admission webhooks to general availability (GA).

* The webhook admission plugin now works even if the API server and the nodes are in two separate networks,for example, in GKE.
The webhook admission plugin now lets the webhook author use the DNS name of the service as the CommonName when generating the server cert for the webhook.
Action required:

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:...

  - When registering with a 1.17+ API server, a CustomResourceDefinition conversion webhook can now request that only `v1` ConversionReview requests be sent to them. Previously, conversion webhooks were required to support receiving `v1beta1` ConversionReview requests as well for...

those `$ref` fields. ([#58438](https://github.com/kubernetes/kubernetes/pull/58438), [@carlory](https://github.com/carlory))

* Webhooks now do not skip cluster-scoped resources. Before upgrading your Kubernetes clusters, double check whether you have configured webhooks for cluster-scoped objects (e.g., nodes, persistentVolume), as these webhooks will start to take effect. Delete/modify the configs if that's not desirable. ([#58185](https://github.com/kubernetes/kubernetes/pull/58185),...