k8s-operator,cmd/k8s-operator: define ProxyGroupPolicy CRD (#18614)

This commit adds a new custom resource definition to the kubernetes
operator named `ProxyGroupPolicy`. This resource is namespace scoped
and is used as an allow list for which `ProxyGroup` resources can be
used within its namespace.

The `spec` contains two fields, `ingress` and `egress`. These should
contain the names of `ProxyGroup` resources to denote which can be
used as values in the `tailscale.com/proxy-group` annotation within
`Service` and `Ingress` resources.

The intention is for these policies to be merged within a namespace and
produce a `ValidatingAdmissionPolicy` and `ValidatingAdmissionPolicyBinding`
for both ingress and egress that prevents users from using names of
`ProxyGroup` resources in those annotations.

Closes: https://github.com/tailscale/corp/issues/36829

Signed-off-by: David Bond <davidsbond93@gmail.com>

k8s-operator/api.md

@@ -16,6 +16,8 @@
 - [ProxyClassList](#proxyclasslist)
 - [ProxyGroup](#proxygroup)
 - [ProxyGroupList](#proxygrouplist)
+- [ProxyGroupPolicy](#proxygrouppolicy)
+- [ProxyGroupPolicyList](#proxygrouppolicylist)
 - [Recorder](#recorder)
 - [RecorderList](#recorderlist)
 - [Tailnet](#tailnet)
@@ -725,6 +727,81 @@ _Appears in:_
 | `items` _[ProxyGroup](#proxygroup) array_ |  |  |  |
 
 
+#### ProxyGroupPolicy
+
+
+
+
+
+
+
+_Appears in:_
+- [ProxyGroupPolicyList](#proxygrouppolicylist)
+
+| Field | Description | Default | Validation |
+| --- | --- | --- | --- |
+| `apiVersion` _string_ | `tailscale.com/v1alpha1` | | |
+| `kind` _string_ | `ProxyGroupPolicy` | | |
+| `kind` _string_ | Kind is a string value representing the REST resource this object represents.<br />Servers may infer this from the endpoint the client submits requests to.<br />Cannot be updated.<br />In CamelCase.<br />More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds |  |  |
+| `apiVersion` _string_ | APIVersion defines the versioned schema of this representation of an object.<br />Servers should convert recognized schemas to the latest internal value, and<br />may reject unrecognized values.<br />More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources |  |  |
+| `metadata` _[ObjectMeta](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.3/#objectmeta-v1-meta)_ | Refer to Kubernetes API documentation for fields of `metadata`. |  |  |
+| `spec` _[ProxyGroupPolicySpec](#proxygrouppolicyspec)_ | Spec describes the desired state of the ProxyGroupPolicy.<br />More info:<br />https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status |  |  |
+| `status` _[ProxyGroupPolicyStatus](#proxygrouppolicystatus)_ | Status describes the status of the ProxyGroupPolicy. This is set<br />and managed by the Tailscale operator. |  |  |
+
+
+#### ProxyGroupPolicyList
+
+
+
+
+
+
+
+
+
+| Field | Description | Default | Validation |
+| --- | --- | --- | --- |
+| `apiVersion` _string_ | `tailscale.com/v1alpha1` | | |
+| `kind` _string_ | `ProxyGroupPolicyList` | | |
+| `kind` _string_ | Kind is a string value representing the REST resource this object represents.<br />Servers may infer this from the endpoint the client submits requests to.<br />Cannot be updated.<br />In CamelCase.<br />More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds |  |  |
+| `apiVersion` _string_ | APIVersion defines the versioned schema of this representation of an object.<br />Servers should convert recognized schemas to the latest internal value, and<br />may reject unrecognized values.<br />More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources |  |  |
+| `metadata` _[ListMeta](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.3/#listmeta-v1-meta)_ | Refer to Kubernetes API documentation for fields of `metadata`. |  |  |
+| `items` _[ProxyGroupPolicy](#proxygrouppolicy) array_ |  |  |  |
+
+
+#### ProxyGroupPolicySpec
+
+
+
+
+
+
+
+_Appears in:_
+- [ProxyGroupPolicy](#proxygrouppolicy)
+
+| Field | Description | Default | Validation |
+| --- | --- | --- | --- |
+| `ingress` _string array_ | Names of ProxyGroup resources that can be used by Ingress resources within this namespace. An empty list<br />denotes that no ingress via ProxyGroups is allowed within this namespace. |  |  |
+| `egress` _string array_ | Names of ProxyGroup resources that can be used by Service resources within this namespace. An empty list<br />denotes that no egress via ProxyGroups is allowed within this namespace. |  |  |
+
+
+#### ProxyGroupPolicyStatus
+
+
+
+
+
+
+
+_Appears in:_
+- [ProxyGroupPolicy](#proxygrouppolicy)
+
+| Field | Description | Default | Validation |
+| --- | --- | --- | --- |
+| `conditions` _[Condition](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.3/#condition-v1-meta) array_ |  |  |  |
+
+
 #### ProxyGroupSpec