*   Webhook admission now takes a config file that describes how to authenticate to webhook servers ([#54414](https://github.com/kubernetes/kubernetes/pull/54414),[ @deads2k](https://github.com/deads2k))

* 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:

## Other notable changes

### API Machinery

- Added port configuration to Admission webhook configuration service reference.
- Added port configuration to AuditSink webhook configuration service reference.
- Added port configuration to CRD Conversion webhook configuration service reference.

        * At Request audit level or higher, an annotation with key "patch.webhook.admission.k8s.io/round_{round idx}_index_{order idx}" get logged with the JSON payload logging the patch sent by a webhook for given request.

- Error messages returned in authentication webhook status responses are now correctly included in the apiserver log ([#73595](https://github.com/kubernetes/kubernetes/pull/73595), [@liggitt](https://github.com/liggitt))

- Kube-apiserver can now specify `--authentication-token-webhook-version=v1` or `--authorization-webhook-version=v1` to use `v1` TokenReview and SubjectAccessReview API objects when communicating with authentication and authorization webhooks. ([#84768](https://github.com/kubernetes/kubernetes/pull/84768), [@liggitt](https://github.com/liggitt))...

    * can be overridden by explicitly specifying the scope values as
    * comma-separated string in the "users[*].config.scopes" field in the
    * KUBECONFIG file.
* kube-apiserver is changed to use SSH tunnels for webhook iff the webhook is not directly routable from apiserver's network environment. ([#58644](https://github.com/kubernetes/kubernetes/pull/58644), [@yguo0905](https://github.com/yguo0905))

* Fix public IP not found issues for VMSS nodes ([#80703](https://github.com/kubernetes/kubernetes/pull/80703), [@feiskyer](https://github.com/feiskyer))
* Resolves a bug that prevented sending a multi-version custom resource to an admission webhook. ([#79495](https://github.com/kubernetes/kubernetes/pull/79495), [@liggitt](https://github.com/liggitt))

- `apiserver_admission_webhook_admission_duration_seconds` buckets have been expanded, 25s is now the largest bucket size to match the webhook default timeout. ([#115802](https://github.com/kubernetes/kubernetes/pull/115802), [@logicalhan](https://github.com/logicalhan)) [SIG API Machinery and Instrumentation]

- Added support for CEL expressions to `v1alpha1 AuthorizationConfiguration` webhook `matchConditions`. ([#121223](https://github.com/kubernetes/kubernetes/pull/121223), [@ritazh](https://github.com/ritazh))