Policy Exceptions

Create an exception to an existing policy using a PolicyException.

Although Kyverno policies contain multiple methods to provide fine-grained control as to which resources they act upon in the form of match/exclude blocks, preconditions at multiple hierarchies, anchors, and more, all these mechanisms have in common that the resources which they are intended to exclude must occur in the same rule definition. This may be limiting in situations where policies may not be directly editable, or doing so imposes an operational burden.

For example, in organizations where multiple teams must interact with the same cluster, a team responsible for policy authoring and administration may not be the same team responsible for submission of resources. In these cases, it can be advantageous to decouple the policy definition from certain exclusions. Additionally, there are often times where an organization or team must allow certain exceptions which would violate otherwise valid rules but on a one-time basis if the risks are known and acceptable.

Imagine a validate policy exists in Enforce mode which mandates all Pods must not mount host namespaces. A separate team has a legitimate need to run a specific tool in this cluster for a limited time which violates this policy. Normally, the policy would block such a “bad” Pod if the policy was not previously altered in such a way to allow said Pod to run. Rather than making adjustments to the policy, an exception may be granted. Both of these examples are use cases for a PolicyException resource described below.

A PolicyException is a Namespaced Custom Resource which allows a resource(s) to be allowed past a given policy and rule combination. It can be used to exempt any resource from any Kyverno rule type although it is primarily intended for use with validate rules. A PolicyException encapsulates the familiar match/exclude statements used in Policy and ClusterPolicy resources but adds an exceptions{} object to select the policy and rule name(s) used to form the exception. A conditions{} block (optional) uses common expressions similar to those found in preconditions and deny rules to query the contents of the selected resources in order to refine the selection process. The logical flow of how a PolicyException works in tandem with a validate policy is depicted below.

An example set of resources is shown below.

A ClusterPolicy exists containing a single validate rule in Enforce mode which requires all Pods must not use any host namespaces via the fields hostPID, hostIPC, or hostNetwork. If any of these fields are defined, they must be set to a value of false.

1apiVersion: kyverno.io/v2beta1 2kind: ClusterPolicy 3metadata: 4 name: disallow-host-namespaces 5spec: 6 background: false 7 rules: 8 - name: host-namespaces 9 match: 10 any: 11 - resources: 12 kinds: 13 - Pod 14 validate: 15 failureAction: Enforce 16 message: >- 17 Sharing the host namespaces is disallowed. The fields spec.hostNetwork, 18 spec.hostIPC, and spec.hostPID must be unset or set to `false`. 19 pattern: 20 spec: 21 =(hostPID): "false" 22 =(hostIPC): "false" 23 =(hostNetwork): "false"
yaml

A cluster administrator wishes to grant an exception to a Pod or Deployment named important-tool which will be created in the delta Namespace. A PolicyException resource is created which specifies the policy name and rule name which should be bypassed as well as the resource kind, Namespace, and name which may bypass it.

1apiVersion: kyverno.io/v2 2kind: PolicyException 3metadata: 4 name: delta-exception 5 namespace: delta 6spec: 7 exceptions: 8 - policyName: disallow-host-namespaces 9 ruleNames: 10 - host-namespaces 11 - autogen-host-namespaces 12 match: 13 any: 14 - resources: 15 kinds: 16 - Pod 17 - Deployment 18 namespaces: 19 - delta 20 names: 21 - important-tool* 22 conditions: 23 any: 24 - key: "{{ request.object.metadata.labels.app || '' }}" 25 operator: Equals 26 value: busybox
yaml

A Deployment matching the characteristics defined in the PolicyException, shown below, will be allowed creation even though it technically violates the rule’s definition.

1apiVersion: apps/v1 2kind: Deployment 3metadata: 4 name: important-tool 5 namespace: delta 6 labels: 7 app: busybox 8spec: 9 replicas: 1 10 selector: 11 matchLabels: 12 app: busybox 13 template: 14 metadata: 15 labels: 16 app: busybox 17 spec: 18 hostIPC: true 19 containers: 20 - image: busybox:1.35 21 name: busybox 22 command: ["sleep", "1d"]
yaml

PolicyExceptions are always Namespaced yet may provide an exception for a cluster-scoped resource as well. There is no correlation between the Namespace in which the PolicyException exists and the Namespace where resources may be excepted.

Exceptions against a ClusterPolicy and those against a (Namespaced) Policy can be disambiguated by specifying the value of the exceptions[].policyName field in the format <namespace>/<policy-name>.

1exceptions: 2- policyName: team-a/disallow-host-namespaces 3 ruleNames: 4 - host-namespaces
yaml

PolicyExceptions also support background scanning, enabled by default. An exception which either explicitly defines spec.background=true or does not define the field at all, will influence Policy Reports when the exception is processed, allowing report results to change from a Fail to a Skip result. When background scans are enabled, PolicyExceptions forbid matching on the same types of fields as those forbidden by validate rules including Roles, ClusterRoles, and user information.

Wildcards ("*") are supported in the value of the ruleNames[] field allowing exception from any/all rules in the policy without having to name them explicitly.

Since PolicyExceptions are just another Custom Resource, their use can and should be controlled by a number of different mechanisms to ensure their creation in a cluster is authorized including:

PolicyExceptions may be subjected to Kyverno validate policies which can be used to provide additional guardrails around how they may be crafted. For example, it is considered a best practice to only allow very narrow exceptions to a much broader rule. Given the case shown earlier, only a Pod or Deployment with the name important-tool would be allowed by the exception, not any Pod or Deployment. Kyverno policy can help ensure, both in the cluster and in a CI/CD process via the CLI, that PolicyExceptions conform to your design standards. Below is an example of a sample policy to illustrate how a Kyverno validate rule ensure that a specific name must be used when creating an exception. For other samples, see the policy library.

1apiVersion: kyverno.io/v2beta1 2kind: ClusterPolicy 3metadata: 4 name: policy-for-exceptions 5spec: 6 background: false 7 rules: 8 - name: require-match-name 9 match: 10 any: 11 - resources: 12 kinds: 13 - PolicyException 14 validate: 15 failureAction: Enforce 16 message: >- 17 An exception must explicitly specify a name for a resource match. 18 pattern: 19 spec: 20 match: 21 =(any): 22 - resources: 23 names: "?*" 24 =(all): 25 - resources: 26 names: "?*"
yaml

Pod Security Exemptions

Kyverno policies can be used to apply Pod Security Standards profiles and controls via the validate.podSecurity subrule. However, there are cases where certain Pods need to be exempted from these policies. For example, a Pod may need to run as root or require privileged access. In such cases, a PolicyException can be used to define an exemption for the Pod through the podSecurity{} block. It can be used to define controls that are exempted from the policy.

Given the following policy that enforces the latest version of the Pod Security Standards restricted profile in a single rule across the entire cluster.

1apiVersion: kyverno.io/v1 2kind: ClusterPolicy 3metadata: 4 name: psa 5spec: 6 background: true 7 rules: 8 - name: restricted 9 match: 10 any: 11 - resources: 12 kinds: 13 - Pod 14 validate: 15 failureAction: Enforce 16 podSecurity: 17 level: restricted 18 version: latest
yaml

In this use case, all Pods in the delta Namespace need to run as a root. A PolicyException can be used to exempt all Pods whose Namespace is delta from the policy by excluding the runAsNonRoot control.

1apiVersion: kyverno.io/v2 2kind: PolicyException 3metadata: 4 name: pod-security-exception 5 namespace: policy-exception-ns 6spec: 7 exceptions: 8 - policyName: psa 9 ruleNames: 10 - restricted 11 match: 12 any: 13 - resources: 14 namespaces: 15 - delta 16 podSecurity: 17 - controlName: "Running as Non-root"
yaml

The following Pod satisfies all controls in the restricted profile except the Running as Non-root control but it matches the exception. Hence, it will be successfully created.

1apiVersion: v1 2kind: Pod 3metadata: 4 name: nginx-pod 5 namespace: delta 6spec: 7 containers: 8 - name: nginx 9 image: nginx 10 args: 11 - sleep 12 - 1d 13 securityContext: 14 seccompProfile: 15 type: RuntimeDefault 16 runAsNonRoot: false 17 allowPrivilegeEscalation: false 18 capabilities: 19 drop: 20 - ALL
yaml

PolicyExceptions podSecurity{} block has the same functionality as the validate.podSecurity.exclude block in the policy itself. They can be used to exempt controls that can only be defined in the container level fields.

For example, the following PolicyException exempts the containers running either the nginx or redis image from following the Capabilities control.

1apiVersion: kyverno.io/v2 2kind: PolicyException 3metadata: 4 name: pod-security-exception 5 namespace: policy-exception-ns 6spec: 7 exceptions: 8 - policyName: psa 9 ruleNames: 10 - restricted 11 match: 12 any: 13 - resources: 14 namespaces: 15 - delta 16 podSecurity: 17 - controlName: Capabilities 18 images: 19 - nginx* 20 - redis*
yaml

There might be a case where it is required to have specific values for the controls in the PodSecurity profile. In such cases, the podSecurity.restrictedField field can be used to define these values for the controls that are exempted from the policy.

For example, service meshes like Istio and Linkerd employ an initContainer that requires some privileges which are very often problematic in security-conscious clusters. Minimally, these initContainers must add two Linux capabilities which allow them to make modifications to the networking stack: NET_ADMIN and NET_RAW. These initContainers may go even further by running as a root user, something which is a big no-no in the world of containers.

In this case, the podSecurity.restrictedField can be used to enforce the entire baseline profile of the Pod Security Standards but only exclude Istio’s and Linkerd’s images from specifically the initContainers list.

The following PolicyException grants an exemption to the initContainers that use Istio or Linkerd images, allowing them to bypass the Capabilities control. This is achieved by permitting the values of NET_ADMIN and NET_RAW in the securityContext.capabilities.add field.

1apiVersion: kyverno.io/v2 2kind: PolicyException 3metadata: 4 name: pod-security-exception 5 namespace: policy-exception-ns 6spec: 7 exceptions: 8 - policyName: psa 9 ruleNames: 10 - baseline 11 match: 12 any: 13 - resources: 14 kinds: 15 - Pod 16 podSecurity: 17 - controlName: Capabilities 18 images: 19 - "*/istio/proxyv2*" 20 - "*/linkerd/proxy-init*" 21 restrictedField: spec.initContainers[*].securityContext.capabilities.add 22 values: 23 - NET_ADMIN 24 - NET_RAW
yaml

The following Pod meets all requirements outlined in the baseline profile, except the Capabilities control in the initContainer. However, it matches the exception that permits the configuration of spec.initContainers[*].securityContext.capabilities.add to include NET_ADMIN and NET_RAW. Hence, it will be successfully created.

1apiVersion: v1 2kind: Pod 3metadata: 4 name: istio-pod 5spec: 6 initContainers: 7 - name: istio-init 8 image: docker.io/istio/proxyv2:1.20.2 9 args: 10 - istio-iptables 11 - -p 12 - "15001" 13 - -z 14 - "15006" 15 - -u 16 - "1337" 17 - -m 18 - REDIRECT 19 - -i 20 - '*' 21 - -x 22 - "" 23 - -b 24 - '*' 25 - -d 26 - 15090,15021,15020 27 - --log_output_level=default:info 28 securityContext: 29 allowPrivilegeEscalation: false 30 capabilities: 31 add: 32 - NET_ADMIN 33 - NET_RAW 34 drop: 35 - ALL 36 privileged: false 37 readOnlyRootFilesystem: false 38 runAsGroup: 0 39 runAsNonRoot: false 40 runAsUser: 0 41 containers: 42 - name: busybox 43 image: busybox:1.35 44 args: 45 - sleep 46 - infinity
yaml

The following Pod meets all requirements outlined in the baseline profile, except the Capabilities control in the initContainer and it matches the exception but it sets the spec.initContainers[*].securityContext.capabilities.add to SYS_ADMIN which isn’t an allowed value. Hence, it will be rejected.

1apiVersion: v1 2kind: Pod 3metadata: 4 name: istio-pod 5spec: 6 initContainers: 7 - name: istio-init 8 image: docker.io/istio/proxyv2:1.20.2 9 args: 10 - istio-iptables 11 - -p 12 - "15001" 13 - -z 14 - "15006" 15 - -u 16 - "1337" 17 - -m 18 - REDIRECT 19 - -i 20 - '*' 21 - -x 22 - "" 23 - -b 24 - '*' 25 - -d 26 - 15090,15021,15020 27 - --log_output_level=default:info 28 securityContext: 29 allowPrivilegeEscalation: false 30 capabilities: 31 add: 32 - NET_ADMIN 33 - NET_RAW 34 - SYS_ADMIN 35 drop: 36 - ALL 37 privileged: false 38 readOnlyRootFilesystem: false 39 runAsGroup: 0 40 runAsNonRoot: false 41 runAsUser: 0 42 containers: 43 - name: busybox 44 image: busybox:1.35 45 args: 46 - sleep 47 - infinity
yaml

PolicyExceptions with CEL Expressions

Since Kyverno 1.14.0, PolicyExceptions, introduced in the new group policies.kyverno.io, support CEL expressions to selectively skip policy enforcement for policy types like ValidatingPolicy and ImageValidatingPolicy in both admission and background modes.

  • A CEL expression under matchConditions dynamically matches target resources (e.g., by name, namespace, or labels).
  • The policyRefs field specifies the policy name and policy kind being excluded from enforcement.
  • If the match condition evaluates to true, the referenced rule is skipped and logged accordingly in PolicyReports.

Using PolicyException with ValidatingPolicy in Admission Mode

The following ValidatingPolicy enforce that all Deployment resources must include the label env=prod. If this condition is not met, the policy denies the request.

1apiVersion: policies.kyverno.io/v1alpha1 2kind: ValidatingPolicy 3metadata: 4 name: require-prod-label 5spec: 6 validationActions: 7 - Deny 8 matchConstraints: 9 resourceRules: 10 - apiGroups: ["apps"] 11 apiVersions: ["v1"] 12 resources: ["deployments"] 13 operations: ["CREATE", "UPDATE"] 14 validations: 15 - expression: >- 16 has(object.metadata.labels) && object.metadata.labels.env == 'prod' 17 messageExpression: "'Deployment must have label env=prod.'"
yaml

To exclude a specific Deployment from the above policy enforcement, a PolicyException can be defined. This example uses a CEL expression to match the Deployment named skipped-deployment, allowing it to bypass the validation.

1apiVersion: policies.kyverno.io/v1alpha1 2kind: PolicyException 3metadata: 4 name: exclude-skipped-deployment 5 namespace: default 6spec: 7 policyRefs: 8 - name: require-prod-label 9 kind: ValidatingPolicy 10 matchConditions: 11 - name: skip-by-name 12 expression: "object.metadata.name == 'skipped-deployment'"
yaml

When the exception is triggered during a live admission request, Kyverno logs the decision in a PolicyReport. Below is an example showing the policy rule was skipped due to the matching PolicyException.

1apiVersion: wgpolicyk8s.io/v1alpha2 2kind: PolicyReport 3metadata: 4 namespace: default 5 labels: 6 app.kubernetes.io/managed-by: kyverno 7 ownerReferences: 8 - apiVersion: apps/v1 9 kind: Deployment 10 name: skipped-deployment 11results: 12 - policy: vpol-report-background-sample 13 rule: exception 14 result: skip 15 message: "rule is skipped due to policy exception: default/exclude-skipped-deployment" 16 properties: 17 exceptions: exclude-skipped-deployment 18 process: admission review 19 source: KyvernoValidatingPolicy 20 scored: true 21scope: 22 apiVersion: apps/v1 23 kind: Deployment 24 name: skipped-deployment 25 namespace: default 26summary: 27 pass: 0 28 fail: 0 29 warn: 0 30 error: 0 31 skip: 1
yaml

Interpreting PolicyReport Results from PolicyException

  • result: skip — indicates the rule was not applied.
  • process: admission review — confirms the evaluation occurred during a live admission request.
  • exceptions: exclude-skipped-deployment — references the applied PolicyException.

Just like in admission mode, PolicyException also functions in background mode and supports other policy type ImageValidatingPolicy.

Using PolicyException with ImageValidatingPolicy in Background Mode

In this example, a Pod named skipped-pod meets the match criteria of the policy. It is located in the default namespace, includes the label prod: true, and references an unsigned image from ghcr.io. as result,this image should fail the background policy evaluation due to missing or invalid attestations and signatures.

1apiVersion: v1 2kind: Pod 3metadata: 4 name: skipped-pod 5 namespace: default 6 labels: 7 prod: "true" 8spec: 9 containers: 10 - name: nginx 11 image: 'ghcr.io/kyverno/test-verify-image:unsigned'
yaml

The ImageValidatingPolicy shown below is configured to run only during background scans, not during admission. It targets Pod resources have the label prod: true. When such a resource is encountered, the policy performs three layers of validation: it verifies the image signature using a provided notary certificate, checks for the presence of an SBOM attestation of type CycloneDX, and confirms that the payload format matches the expected structure.

1apiVersion: policies.kyverno.io/v1alpha1 2kind: ImageValidatingPolicy 3metadata: 4 name: ivpol-sample 5spec: 6 webhookConfiguration: 7 timeoutSeconds: 20 8 failurePolicy: Ignore 9 evaluation: 10 admission: 11 enabled: false 12 background: 13 enabled: true 14 validationActions: 15 - Audit 16 matchConstraints: 17 resourceRules: 18 - apiGroups: [""] 19 apiVersions: ["v1"] 20 operations: ["CREATE"] 21 resources: ["pods"] 22 matchConditions: 23 - name: "check-prod-label" 24 expression: >- 25 has(object.metadata.labels) && has(object.metadata.labels.prod) && object.metadata.labels.prod == 'true' 26 matchImageReferences: 27 - glob: ghcr.io/* 28 attestors: 29 - name: notary 30 notary: 31 certs: 32 value: |- 33 -----BEGIN CERTIFICATE----- 34 MIIDTTCCAjWgAwIBAgIJAPI+zAzn4s0xMA0GCSqGSIb3DQEBCwUAMEwxCzAJB 35 ... 36 -----END CERTIFICATE----- 37 attestations: 38 - name: sbom 39 referrer: 40 type: sbom/cyclone-dx 41 validations: 42 - expression: >- 43 images.containers.map(image, verifyImageSignatures(image, [attestors.notary])).all(e, e > 0) 44 message: failed to verify image with notary cert 45 - expression: >- 46 images.containers.map(image, verifyAttestationSignatures(image, attestations.sbom, [attestors.notary])).all(e, e > 0) 47 message: failed to verify attestation with notary cert 48 - expression: >- 49 images.containers.map(image, extractPayload(image, attestations.sbom).bomFormat == 'CycloneDX').all(e, e) 50 message: sbom is not a cyclone dx sbom
yaml

This PolicyException is defined to exempt this pod from enforcement. The exception uses a CEL expression—object.metadata.name == 'skipped-pod'to identify the specific resource. It links to the ImageValidatingPolicy named ivpol-sample, and when the background controller processes the pod, it detects that the exception applies. As a result, none of the image validation rules are executed for this resource.

1apiVersion: policies.kyverno.io/v1alpha1 2kind: PolicyException 3metadata: 4 name: check-name 5spec: 6 policyRefs: 7 - name: ivpol-sample 8 kind: ImageValidatingPolicy 9 matchConditions: 10 - name: "check-name" 11 expression: "object.metadata.name == 'skipped-pod'"
yaml

Kyverno background controller evaluates the pod. It detects that the resource matches the PolicyException and Kyverno logs the decision in a PolicyReport

1apiVersion: wgpolicyk8s.io/v1alpha2 2kind: PolicyReport 3metadata: 4 namespace: default 5 labels: 6 app.kubernetes.io/managed-by: kyverno 7 ownerReferences: 8 - apiVersion: v1 9 kind: Pod 10 name: skipped-pod 11results: 12 - policy: ivpol-sample 13 rule: exception 14 result: skip 15 message: "rule is skipped due to policy exception: " 16 properties: 17 exceptions: check-name 18 process: background scan 19 source: KyvernoImageValidatingPolicy 20 scored: true 21scope: 22 apiVersion: v1 23 kind: Pod 24 name: skipped-pod 25 namespace: default 26summary: 27 pass: 0 28 fail: 0 29 warn: 0 30 error: 0 31 skip: 1
yaml

Interpreting PolicyReport Results from PolicyException

  • result: skip — indicates the rule was not applied.
  • process: background scan — confirms the evaluation occurred during a background policy check.
  • exceptions: check-name — references the applied PolicyException.

This enables fine-grained, declarative exemptions without modifying the core policy logic, keeping your security posture strong while allowing flexibility for exceptional cases.


Last modified April 29, 2025 at 2:41 PM PST: add docs for policyException (cherry-pick #1540) (#1544) (3bdfdf7)