([#123611](https://github.com/kubernetes/kubernetes/pull/123611), [@ritazh](https://github.com/ritazh))

its lazily evaluated value.\n  For example, a variable named 'foo' can be accessed as 'variables.foo'.\n- 'authorizer' - A CEL Authorizer. May be used to perform authorization checks for the principal (user or service account) of the request.\n  See https://pkg.go.dev/k8s.io/apiserver/pkg/cel/library#Authz\n- 'authorizer.requestResource' - A CEL ResourceCheck constructed from the 'authorizer' and configured with the\n  request resource.\n\nThe `apiVersion`, `kind`, `metadata.name` and `metadata.generateName`...

### RBAC
* The `attributeRestrictions` field has been removed from the PolicyRule type in the rbac.authorization.k8s.io/v1alpha1 API. The field was not used by the RBAC authorizer. ([#39625](https://github.com/kubernetes/kubernetes/pull/39625), [@deads2k](https://github.com/deads2k))

- In the course of admitting a single request, the ValidatingAdmissionPolicy plugin will perform no more than one authorization check per unique authorizer expression. All evaluations of identical authorizer expressions will produce the same decision. ([#116443](https://github.com/kubernetes/kubernetes/pull/116443), [@benluddy](https://github.com/benluddy)) [SIG API Machinery and Testing]

          "kind": {
            "default": "",
            "description": "Kind of object being referenced. Values defined by this API group are \"User\", \"Group\", and \"ServiceAccount\". If the Authorizer does not recognized the kind value, the Authorizer should report an error.",
            "type": "string"
          },
          "name": {
            "default": "",
            "description": "Name of the object being referenced.",

## Changelog since v1.8.0-beta.1

### Action Required

* New GCE or GKE clusters created with `cluster/kube-up.sh` will not enable the legacy ABAC authorizer by default. If you would like to enable the legacy ABAC authorizer, export ENABLE_LEGACY_ABAC=true before running `cluster/kube-up.sh`. ([#51367](https://github.com/kubernetes/kubernetes/pull/51367), [@cjcullen](https://github.com/cjcullen))

        * Nodes must use client credentials that place them in the `system:nodes` group with a username of `system:node:<nodeName>` in order to be authorized by the node authorizer (the credentials obtained by the kubelet...

* Add support for the webhook authorizer to make a Deny decision that short-circuits the union authorizer and immediately returns Deny.  ([#53273](https://github.com/kubernetes/kubernetes/pull/53273), [@mikedanese](https://github.com/mikedanese))

- Improves performance of the node authorizer ([#87696](https://github.com/kubernetes/kubernetes/pull/87696), [@liggitt](https://github.com/liggitt)) [SIG Auth]

[API Aggregation](https://github.com/kubernetes/enhancements/issues/263) has been upgraded to "stable" in Kubernetes 1.10, so you can use it in production. Webhooks have seen numerous improvements, including alpha [Support for self-hosting authorizer webhooks](https://github.com/kubernetes/enhancements/issues/516).

### Auth