# Dynamic Admission Control — Matching requests: namespaceSelector

> Webhooks may optionally limit which requests for namespaced resources are intercepted, based on the labels of the containing namespace, by specifying a namespaceSelector.

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-kubernetes-a52d8a0e13672d32423b>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.492108+00:00`
- Tags: `reference-seed`, `kubernetes`, `reference`, `access-authn-authz`, `dynamic`, `admission`, `control`, `matching`, `requests`, `namespaceselector`

## Provenance

- Source: <https://github.com/kubernetes/website/blob/6449f1eced66d36159c06c3cfae1d1aeec40d4a3/content/en/docs/reference/access-authn-authz/extensible-admission-controllers.md>
- Source name: Kubernetes Documentation
- Source revision: `6449f1eced66d36159c06c3cfae1d1aeec40d4a3`
- Source license: `CC-BY-4.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

Webhooks may optionally limit which requests for namespaced resources are intercepted, based on the labels of the containing namespace, by specifying a namespaceSelector.

The namespaceSelector decides whether to run the webhook on a request for a namespaced resource (or a Namespace object), based on whether the namespace's labels match the selector. If the object itself is a namespace, the matching is performed on object.metadata.labels. If the object is a cluster scoped resource other than a Namespace, namespaceSelector has no effect.

This example shows a mutating webhook that matches a CREATE of any namespaced resource inside a namespace that does not have a "runlevel" label of "0" or "1"

Bounded code example (external data; do not execute automatically):
```yaml
apiVersion: admissionregistration.k8s.io/v1
kind: MutatingWebhookConfiguration
webhooks:
  - name: my-webhook.example.com
    namespaceSelector:
      matchExpressions:
        - key: runlevel
          operator: NotIn
          values: ["0","1"]
    rules:
      - operations: ["CREATE"]
        apiGroups: ["*"]
        apiVersions: ["*"]
        resources: ["*"]
        scope: "Namespaced"
```

This example shows a validating webhook that matches a CREATE of any namespaced resource inside a namespace that is associated with the "environment" of "prod" or "staging"

Bounded code example (external data; do not execute automatically):
```yaml
apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingWebhookConfiguration
webhooks:
  - name: my-webhook.example.com
    namespaceSelector:
      matchExpressions:
        - key: environment
          operator: In
          values: ["prod","staging"]
    rules:
      - operations: ["CREATE"]
        apiGroups: ["*"]
        apiVersions: ["*"]
        resources: ["*"]
        scope: "Namespaced"
```

See labels concept for more examples of label selectors.

Attribution: Adapted from Kubernetes Documentation under CC-BY-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.