apply

The apply command is used to perform a dry run on one or more policies with a given set of input resources. This can be useful to determine a policy’s effectiveness prior to committing to a cluster. In the case of mutate policies, the apply command can show the mutated resource as an output. The input resources can either be resource manifests (one or multiple) or can be taken from a running Kubernetes cluster. The apply command supports files from URLs both as policies and resources.

Apply to a resource:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml

Apply a policy to all matching resources in a cluster based on the current kubectl context:

kyverno apply /path/to/policy.yaml --cluster

The resources can also be passed from stdin:

kustomize build nginx/overlays/envs/prod/ | kyverno apply /path/to/policy.yaml --resource -

Apply all cluster policies in the current cluster to all matching resources in a cluster based on the current kubectl context:

kubectl get clusterpolicies -o yaml | kyverno apply - --cluster

Apply multiple policies to multiple resources:

kyverno apply /path/to/policy1.yaml /path/to/folderFullOfPolicies --resource /path/to/resource1.yaml --resource /path/to/resource2.yaml --cluster

Apply a policy to a resource with a policy exception:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml --exception /path/to/exception.yaml

Apply multiple policies to multiple resources with exceptions:

kyverno apply /path/to/policy1.yaml /path/to/folderFullOfPolicies --resource /path/to/resource1.yaml --resource /path/to/resource2.yaml --exception /path/to/exception1.yaml --exception /path/to/exception2.yaml

Apply multiple policies to multiple resources where exceptions are evaluated from the provided resources:

kyverno apply /path/to/policy1.yaml /path/to/folderFullOfPolicies --resource /path/to/resource1.yaml --resource /path/to/resource2.yaml --exceptions-with-resources

Apply a mutation policy to a specific resource:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml

applying 1 policy to 1 resource...

mutate policy <policy_name> applied to <resource_name>:
<final mutated resource output>

Save the mutated resource to a file:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml -o newresource.yaml

Save the mutated resource to a directory:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml -o foo/

Run a policy with a mutate existing rule on a group of target resources:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml  --target-resource /path/to/target1.yaml --target-resource /path/to/target2.yaml

Applying 1 policy rule(s) to 1 resource(s)...

mutate policy <policy-name> applied to <trigger-name>:
<trigger-resource>
---
patched targets:

<patched-target1>
---

<patched-target2>
---

pass: 2, fail: 0, warn: 0, error: 0, skip: 0

Run a policy with a mutate existing rule on target resources from a directory:

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml  --target-resources /path/to/targets/

Applying 1 policy rule(s) to 1 resource(s)...

mutate policy <policy-name> applied to <trigger-name>:
<trigger-resource>
---
patched targets:

<patched-targets>

pass: 5, fail: 0, warn: 0, error: 0, skip: 0

Apply a policy containing variables using the --set or -s flag to pass in the values. Variables that begin with {{request.object}} normally do not need to be specified as these will be read from the resource.

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml --set <variable1>=<value1>,<variable2>=<value2>

Use -f or --values-file for applying multiple policies to multiple resources while passing a file containing variables and their values. Variables specified can be of various types include AdmissionReview fields, ConfigMap context data, API call context data, and Global Context Entries.

Use -u or --userinfo for applying policies while passing an optional user_info.yaml file which contains necessary admission request data made during the request.

Note

When passing ConfigMap array data into the values file, the data must be formatted as JSON outlined here.

kyverno apply /path/to/policy1.yaml /path/to/policy2.yaml --resource /path/to/resource1.yaml --resource /path/to/resource2.yaml -f /path/to/value.yaml --userinfo /path/to/user_info.yaml

Format of value.yaml with all possible fields:

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
policies:
  - name: <policy1 name>
    rules:
      - name: <rule1 name>
        values:
          <context variable1 in policy1 rule1>: <value>
          <context variable2 in policy1 rule1>: <value>
      - name: <rule2 name>
        values:
          <context variable1 in policy1 rule2>: <value>
          <context variable2 in policy1 rule2>: <value>
    resources:
      - name: <resource1 name>
        values:
          <variable1 in policy1>: <value>
          <variable2 in policy1>: <value>
      - name: <resource2 name>
        values:
          <variable1 in policy1>: <value>
          <variable2 in policy1>: <value>
namespaceSelector:
  - name: <namespace1 name>
    labels:
      <label key>: <label value>
  - name: <namespace2 name>
    labels:
      <label key>: <label value>

Format of user_info.yaml:

apiVersion: cli.kyverno.io/v1alpha1
kind: UserInfo
metadata:
  name: user-info
clusterRoles:
  - admin
userInfo:
  username: molybdenum@somecorp.com

Example:

Policy manifest (add_network_policy.yaml):

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: add-networkpolicy
spec:
  background: false
  rules:
    - name: default-deny-ingress
      match:
        any:
          - resources:
              kinds:
                - Namespace
            clusterRoles:
              - cluster-admin
      generate:
        apiVersion: networking.k8s.io/v1
        kind: NetworkPolicy
        name: default-deny-ingress
        namespace: '{{request.object.metadata.name}}'
        synchronize: true
        data:
          spec:
            # select all pods in the namespace
            podSelector: {}
            policyTypes:
              - Ingress

Resource manifest (required_default_network_policy.yaml):

kind: Namespace
apiVersion: v1
metadata:
  name: devtest

Apply a policy to a resource using the --set or -s flag to pass a variable directly:

kyverno apply /path/to/add_network_policy.yaml --resource /path/to/required_default_network_policy.yaml -s request.object.metadata.name=devtest

Apply a policy to a resource using the --values-file or -f flag:

YAML file containing variables (value.yaml):

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
policies:
  - name: add-networkpolicy
    resources:
      - name: devtest
        values:
          request.namespace: devtest

kyverno apply /path/to/add_network_policy.yaml --resource /path/to/required_default_network_policy.yaml -f /path/to/value.yaml

On applying the above policy to the mentioned resources, the following output will be generated:

Applying 1 policy to 1 resource...
(Total number of result count may vary as the policy is mutated by Kyverno. To check the mutated policy please try with log level 5)

pass: 1, fail: 0, warn: 0, error: 0, skip: 0

The summary count is based on the number of rules applied on the number of resources.

Value files also support global values, which can be passed to all resources the policy is being applied to.

Format of value.yaml:

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
policies:
  - name: <policy1 name>
    resources:
      - name: <resource1 name>
        values:
          <variable1 in policy1>: <value>
          <variable2 in policy1>: <value>
      - name: <resource2 name>
        values:
          <variable1 in policy1>: <value>
          <variable2 in policy1>: <value>
  - name: <policy2 name>
    resources:
      - name: <resource1 name>
        values:
          <variable1 in policy2>: <value>
          <variable2 in policy2>: <value>
      - name: <resource2 name>
        values:
          <variable1 in policy2>: <value>
          <variable2 in policy2>: <value>
globalValues:
  <global variable1>: <value>
  <global variable2>: <value>

If a resource-specific value and a global value have the same variable name, the resource value takes precedence over the global value. See the Pod test-global-prod in the following example.

Example:

Policy manifest (add_dev_pod.yaml):

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: cm-globalval-example
spec:
  background: false
  rules:
    - name: validate-mode
      match:
        any:
          - resources:
              kinds:
                - Pod
      validate:
        failureAction: Enforce
        message: "The value {{ request.mode }} for val1 is not equal to 'dev'."
        deny:
          conditions:
            any:
              - key: '{{ request.mode }}'
                operator: NotEquals
                value: dev

Resource manifest (dev_prod_pod.yaml):

apiVersion: v1
kind: Pod
metadata:
  name: test-global-prod
spec:
  containers:
    - name: nginx
      image: nginx:latest
---
apiVersion: v1
kind: Pod
metadata:
  name: test-global-dev
spec:
  containers:
    - name: nginx
      image: nginx:1.12

YAML file containing variables (value.yaml):

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
policies:
  - name: cm-globalval-example
    resources:
      - name: test-global-prod
        values:
          request.mode: prod
globalValues:
  request.mode: dev

kyverno apply /path/to/add_dev_pod.yaml --resource /path/to/dev_prod_pod.yaml -f /path/to/value.yaml

The Pod test-global-dev passes the validation, and test-global-prod fails.

Apply a policy with the Namespace selector:

Use --values-file or -f for passing a file containing Namespace details. Check here to know more about Namespace selectors.

kyverno apply /path/to/policy1.yaml /path/to/policy2.yaml --resource /path/to/resource1.yaml --resource /path/to/resource2.yaml -f /path/to/value.yaml

Format of value.yaml:

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
namespaceSelector:
  - name: <namespace1 name>
    labels:
      <namespace label key>: <namespace label value>
  - name: <namespace2 name>
    labels:
      <namespace label key>: <namespace label value>

Example:

Policy manifest (enforce-pod-name.yaml):

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: enforce-pod-name
spec:
  background: true
  rules:
    - name: validate-name
      match:
        any:
          - resources:
              kinds:
                - Pod
              namespaceSelector:
                matchExpressions:
                  - key: foo.com/managed-state
                    operator: In
                    values:
                      - managed
      validate:
        failureAction: Audit
        message: 'The Pod must end with -nginx'
        pattern:
          metadata:
            name: '*-nginx'

Resource manifest (nginx.yaml):

kind: Pod
apiVersion: v1
metadata:
  name: test-nginx
  namespace: test1
spec:
  containers:
    - name: nginx
      image: nginx:latest

Namespace manifest (namespace.yaml):

apiVersion: v1
kind: Namespace
metadata:
  name: test1
  labels:
    foo.com/managed-state: managed

YAML file containing variables (value.yaml):

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
namespaceSelector:
  - name: test1
    labels:
      foo.com/managed-state: managed

To test the above policy, use the following command:

kyverno apply /path/to/enforce-pod-name.yaml --resource /path/to/nginx.yaml -f /path/to/value.yaml

Apply a resource to a policy which uses a context variable:

Use --values-file or -f for passing a file containing the context variable.

kyverno apply /path/to/policy1.yaml --resource /path/to/resource1.yaml -f /path/to/value.yaml

policy1.yaml

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: cm-variable-example
  annotations:
    pod-policies.kyverno.io/autogen-controllers: DaemonSet,Deployment,StatefulSet
spec:
  background: false
  rules:
    - name: example-configmap-lookup
      context:
        - name: dictionary
          configMap:
            name: mycmap
            namespace: default
      match:
        any:
          - resources:
              kinds:
                - Pod
      mutate:
        patchStrategicMerge:
          metadata:
            labels:
              my-environment-name: '{{dictionary.data.env}}'

resource1.yaml

apiVersion: v1
kind: Pod
metadata:
  name: nginx-config-test
spec:
  containers:
    - image: nginx:latest
      name: test-nginx

value.yaml

apiVersion: cli.kyverno.io/v1alpha1
kind: Values
metadata:
  name: values
policies:
  - name: cm-variable-example
    rules:
      - name: example-configmap-lookup
        values:
          dictionary.data.env: dev1

You can also inject global context entries using variables. Here’s an example of a Values file that injects a global context entry:

apiVersion: cli.kyverno.io/v1alpha1
kind: Value
metadata:
  name: values
globalValues:
  request.operation: CREATE
policies:
  - name: gctx
    rules:
      - name: main-deployment-exists
        values:
          deploymentCount: 1

In this example, request.operation is set as a global value, and deploymentCount is set for a specific rule in the gctx policy.

Policies that have their failureAction set to Audit can be set to produce a warning instead of a failure using the --audit-warn flag. This will also cause a non-zero exit code if no enforcing policies failed.

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml --audit-warn

Additionally, you can use the --warn-exit-code flag with the apply command to control the exit code when warnings are reported. This is useful in CI/CD systems when used with the --audit-warn flag to treat Audit policies as warnings. When no failures or errors are found, but warnings are encountered, the CLI will exit with the defined exit code.

kyverno apply disallow-latest-tag.yaml --resource=echo-test.yaml --audit-warn --warn-exit-code 3
echo $?
3

You can also use --warn-exit-code in combination with --warn-no-pass flag to make the CLI exit with the warning code if no objects were found that satisfy a policy. This may be useful during the initial development of a policy or if you want to make sure that an object exists in the Kubernetes manifest.

kyverno apply disallow-latest-tag.yaml --resource=empty.yaml --warn-exit-code 3 --warn-no-pass
echo $?
3

Policy Report

Policy reports provide information about policy execution and violations. Use --policy-report with the apply command to generate a policy report for validate policies. mutate and generate policies do not trigger policy reports.

Policy reports can also be generated for a live cluster. While generating a policy report for a live cluster the -r flag, which declares a resource, is assumed to be globally unique. And it doesn’t support naming the resource type (ex., Pod/foo when the cluster contains resources of different types with the same name). To generate a policy report for a live cluster use --cluster with --policy-report.

kyverno apply policy.yaml --cluster --policy-report

Above example applies a policy.yaml to all resources in the cluster.

Below are the combination of inputs that can be used for generating the policy report from the Kyverno CLI.

Policy	Resource	Cluster	Namespace	Interpretation
policy.yaml	-r resource.yaml	false		Apply policy from policy.yaml to the resources specified in resource.yaml
policy.yaml	-r resourceName	true		Apply policy from policy.yaml to the resource with a given name in the cluster
policy.yaml		true		Apply policy from policy.yaml to all the resources in the cluster
policy.yaml	-r resourceName	true	-n=namespaceName	Apply policy from policy.yaml to the resource with a given name in a specific Namespace
policy.yaml		true	-n=namespaceName	Apply policy from policy.yaml to all the resources in a specific Namespace

Example:

Consider the following policy and resources:

policy.yaml

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: require-pod-requests-limits
spec:
  rules:
    - name: validate-resources
      match:
        any:
          - resources:
              kinds:
                - Pod
      validate:
        failureAction: Audit
        message: 'CPU and memory resource requests and limits are required'
        pattern:
          spec:
            containers:
              - resources:
                  requests:
                    memory: '?*'
                    cpu: '?*'
                  limits:
                    memory: '?*'

resource1.yaml

apiVersion: v1
kind: Pod
metadata:
  name: nginx1
  labels:
    env: test
spec:
  containers:
    - name: nginx
      image: nginx
      imagePullPolicy: IfNotPresent
      resources:
        requests:
          memory: '64Mi'
          cpu: '250m'
        limits:
          memory: '128Mi'
          cpu: '500m'

resource2.yaml

apiVersion: v1
kind: Pod
metadata:
  name: nginx2
  labels:
    env: test
spec:
  containers:
    - name: nginx
      image: nginx
      imagePullPolicy: IfNotPresent

Case 1: Apply a policy manifest to multiple resource manifests

kyverno apply policy.yaml -r resource1.yaml -r resource2.yaml --policy-report

Case 2: Apply a policy manifest to multiple resources in the cluster

Create the resources by first applying manifests resource1.yaml and resource2.yaml.

kyverno apply policy.yaml -r nginx1 -r nginx2 --cluster --policy-report

Case 3: Apply a policy manifest to all resources in the cluster

kyverno apply policy.yaml --cluster --policy-report

Given the contents of policy.yaml shown earlier, this will produce a report validating against all Pods in the cluster.

Case 4: Apply a policy manifest to multiple resources by name within a specific Namespace

kyverno apply policy.yaml -r nginx1 -r nginx2 --cluster --policy-report -n default

Case 5: Apply a policy manifest to all resources within the default Namespace

kyverno apply policy.yaml --cluster --policy-report -n default

Given the contents of policy.yaml shown earlier, this will produce a report validating all Pods within the default Namespace.

On applying policy.yaml to the mentioned resources, the following report will be generated:

apiVersion: wgpolicyk8s.io/v1alpha1
kind: ClusterPolicyReport
metadata:
  name: clusterpolicyreport
results:
  - message: Validation rule 'validate-resources' succeeded.
    policy: require-pod-requests-limits
    resources:
      - apiVersion: v1
        kind: Pod
        name: nginx1
        namespace: default
    rule: validate-resources
    scored: true
    status: pass
  - message: 'Validation error: CPU and memory resource requests and limits are required; Validation rule validate-resources failed at path /spec/containers/0/resources/limits/'
    policy: require-pod-requests-limits
    resources:
      - apiVersion: v1
        kind: Pod
        name: nginx2
        namespace: default
    rule: validate-resources
    scored: true
    status: fail
summary:
  error: 0
  fail: 1
  pass: 1
  skip: 0
  warn: 0

Applying Policy Exceptions

Policy Exceptions can be applied alongside policies by using the -e or --exceptions flag to pass the Policy Exception manifest.

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml --exception /path/to/exception.yaml

Example:

Applying a policy to a resource with a policy exception.

Policy manifest (policy.yaml):

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: max-containers
spec:
  background: false
  rules:
    - name: max-two-containers
      match:
        any:
          - resources:
              kinds:
                - Pod
      validate:
        failureAction: Enforce
        message: 'A maximum of 2 containers are allowed inside a Pod.'
        deny:
          conditions:
            any:
              - key: '{{request.object.spec.containers[] | length(@)}}'
                operator: GreaterThan
                value: 2

Policy Exception manifest (exception.yaml):

apiVersion: kyverno.io/v2
kind: PolicyException
metadata:
  name: container-exception
spec:
  exceptions:
    - policyName: max-containers
      ruleNames:
        - max-two-containers
        - autogen-max-two-containers
  match:
    any:
      - resources:
          kinds:
            - Pod
            - Deployment
  conditions:
    any:
      - key: "{{ request.object.metadata.labels.color || '' }}"
        operator: Equals
        value: blue

Resource manifest (resource.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.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: three-containers-deployment
  labels:
    app: my-app
    color: blue
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
        color: blue
    spec:
      containers:
        - name: nginx-container
          image: nginx:latest
          ports:
            - containerPort: 80
        - name: redis-container
          image: redis:latest
          ports:
            - containerPort: 6379
        - name: busybox-container
          image: busybox:latest
          command:
            [
              '/bin/sh',
              '-c',
              "while true; do echo 'Hello from BusyBox'; sleep 10; done",
            ]

Apply the above policy to the resource with the exception

kyverno apply /path/to/policy.yaml --resource /path/to/resource.yaml --exception /path/to/exception.yaml

The following output will be generated:

Applying 3 policy rule(s) to 1 resource(s) with 1 exception(s)...

pass: 0, fail: 0, warn: 0, error: 0, skip: 1

Kubernetes Native Policies

The kyverno apply command can be used to apply native Kubernetes policies and their corresponding bindings to resources, allowing you to test them locally without a cluster.

ValidatingAdmissionPolicy

With the apply command, Kubernetes ValidatingAdmissionPolicies can be applied to resources as follows:

Policy manifest (check-deployment-replicas.yaml):

apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicy
metadata:
  name: check-deployments-replicas
spec:
  failurePolicy: Fail
  matchConstraints:
    resourceRules:
      - apiGroups: ['apps']
        apiVersions: ['v1']
        operations: ['CREATE', 'UPDATE']
        resources: ['deployments']
  validations:
    - expression: 'object.spec.replicas <= 3'
      message: 'Replicas must be less than or equal 3'

Resource manifest (deployment.yaml):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-pass
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx-pass
  template:
    metadata:
      labels:
        app: nginx-pass
    spec:
      containers:
        - name: nginx-server
          image: nginx

Apply the ValidatingAdmissionPolicy to the resource:

kyverno apply /path/to/check-deployment-replicas.yaml --resource /path/to/deployment.yaml

The following output will be generated:

Applying 1 policy rule(s) to 1 resource(s)...

pass: 1, fail: 0, warn: 0, error: 0, skip: 0

The below example applies a ValidatingAdmissionPolicyBinding along with the policy to all resources in the cluster.

Policy manifest (check-deployment-replicas.yaml):

apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicy
metadata:
  name: 'check-deployment-replicas'
spec:
  matchConstraints:
    resourceRules:
      - apiGroups:
          - apps
        apiVersions:
          - v1
        operations:
          - CREATE
          - UPDATE
        resources:
          - deployments
  validations:
    - expression: object.spec.replicas <= 5
---
apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicyBinding
metadata:
  name: 'check-deployment-replicas-binding'
spec:
  policyName: 'check-deployment-replicas'
  validationActions: [Deny]
  matchResources:
    namespaceSelector:
      matchLabels:
        environment: staging

The above policy verifies that the number of deployment replicas is not greater than 5 and is limited to a namespace labeled environment: staging.

Create a Namespace with the label environment: staging:

kubectl create ns staging
kubectl label ns staging environment=staging

Create two Deployments, one of them in the staging namespace, which violates the policy.

kubectl create deployment nginx-1 --image=nginx --replicas=6 -n staging
kubectl create deployment nginx-2 --image=nginx --replicas=6

Get all Deployments from the cluster:

kubectl get deployments -A

NAMESPACE            NAME                     READY   UP-TO-DATE   AVAILABLE   AGE
default              nginx-2                  6/6     6            6           7m26s
kube-system          coredns                  2/2     2            2           13m
local-path-storage   local-path-provisioner   1/1     1            1           13m
staging              nginx-1                  6/6     6            6           7m44s

Apply the ValidatingAdmissionPolicy with its binding to all resources in the cluster:

kyverno apply /path/to/check-deployment-replicas.yaml --cluster --policy-report

The following output will be generated:

Applying 1 policy rule(s) to 4 resource(s)...
----------------------------------------------------------------------
POLICY REPORT:
----------------------------------------------------------------------
apiVersion: wgpolicyk8s.io/v1alpha2
kind: ClusterPolicyReport
metadata:
  creationTimestamp: null
  name: merged
results:
- message: 'failed expression: object.spec.replicas <= 5'
  policy: check-deployment-replicas
  resources:
  - apiVersion: apps/v1
    kind: Deployment
    name: nginx-1
    namespace: staging
    uid: a95d1594-44a7-4c8a-9225-04ac34cb9494
  result: fail
  scored: true
  source: kyverno
  timestamp:
    nanos: 0
    seconds: 1707394871
summary:
  error: 0
  fail: 1
  pass: 0
  skip: 0
  warn: 0

As expected, the policy is only applied to nginx-1 as it matches both the policy definition and its binding.

MutatingAdmissionPolicy

Similarly, you can test a MutatingAdmissionPolicy to preview the changes it would make to a resource. The CLI will output the final, mutated resource.

Example 1: Basic Mutation

For instance, you can test a MutatingAdmissionPolicy that adds a label to a ConfigMap.

Policy manifest (add-label-to-configmap.yaml):

apiVersion: admissionregistration.k8s.io/v1alpha1
kind: MutatingAdmissionPolicy
metadata:
  name: 'add-label-to-configmap'
spec:
  matchConstraints:
    resourceRules:
      - apiGroups: ['']
        apiVersions: ['v1']
        operations: ['CREATE']
        resources: ['configmaps']
  failurePolicy: Fail
  reinvocationPolicy: Never
  mutations:
    - patchType: 'ApplyConfiguration'
      applyConfiguration:
        expression: >
          object.metadata.?labels["lfx-mentorship"].hasValue() ?
              Object{} :
              Object{ metadata: Object.metadata{ labels: {"lfx-mentorship": "kyverno"}}}

Resource manifest (configmap.yaml):

apiVersion: v1
kind: ConfigMap
metadata:
  name: game-demo
  labels:
    app: game
data:
  player_initial_lives: '3'

Now, apply the MutatingAdmissionPolicy to the ConfigMap resource:

kyverno apply /path/to/add-label-to-configmap.yaml --resource /path/to/configmap.yaml

The output will show the mutated ConfigMap with the added label:

Applying 1 policy rule(s) to 1 resource(s)...

policy add-label-to-configmap applied to default/ConfigMap/game-demo:
apiVersion: v1
data:
  player_initial_lives: "3"
kind: ConfigMap
metadata:
  labels:
    app: game
    lfx-mentorship: kyverno
  name: game-demo
  namespace: default
---

Mutation has been applied successfully.
pass: 1, fail: 0, warn: 0, error: 0, skip: 0

The output displays the ConfigMap with the new lfx-mentorship: kyverno label, confirming the mutation was applied correctly.

Example 2: Mutation with a Binding and Namespace Selector

You can also test policies that include a MutatingAdmissionPolicyBinding to control where the policy is applied. This example makes use of a namespace selector to apply the policy only to ConfigMaps in a specific namespace.

To do this, you must provide a values.yaml file to simulate the labels of the Namespaces your resources belong to.

Policy manifest (add-label-to-configmap.yaml):

This file defines a policy to add a label and a binding that restricts it to Namespaces labeled environment: staging or environment: production.

apiVersion: admissionregistration.k8s.io/v1alpha1
kind: MutatingAdmissionPolicy
metadata:
  name: 'add-label-to-configmap'
spec:
  matchConstraints:
    resourceRules:
      - apiGroups: ['']
        apiVersions: ['v1']
        operations: ['CREATE']
        resources: ['configmaps']
  failurePolicy: Fail
  reinvocationPolicy: Never
  mutations:
    - patchType: 'ApplyConfiguration'
      applyConfiguration:
        expression: >
          object.metadata.?labels["lfx-mentorship"].hasValue() ?
              Object{} :
              Object{ metadata: Object.metadata{ labels: {"lfx-mentorship": "kyverno"}}}
---
apiVersion: admissionregistration.k8s.io/v1alpha1
kind: MutatingAdmissionPolicyBinding
metadata:
  name: 'add-label-to-configmap-binding'
spec:
  policyName: 'add-label-to-configmap'
  matchResources:
    namespaceSelector:
      matchExpressions:
        - key: environment
          operator: In
          values:
            - staging
            - production

Resource manifest (configmaps.yaml):

This file contains three ConfigMap resources in different Namespaces. Only the ones in staging and production should be mutated.

apiVersion: v1
kind: ConfigMap
metadata:
  name: matched-cm-1
  namespace: staging
  labels:
    color: red
data:
  player_initial_lives: '3'
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: matched-cm-2
  namespace: production
  labels:
    color: red
data:
  player_initial_lives: '3'
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: unmatched-cm
  namespace: testing
  labels:
    color: blue
data:
  player_initial_lives: '3'

Values file (values.yaml):

This file provides the necessary context. It tells the Kyverno CLI what labels are associated with the staging, production, and testing Namespaces so it can correctly evaluate the namespaceSelector in the binding.

apiVersion: cli.kyverno.io/v1alpha1
kind: Value
metadata:
  name: values
namespaceSelector:
  - labels:
      environment: staging
    name: staging
  - labels:
      environment: production
    name: production
  - labels:
      environment: testing
    name: testing

Now, apply the MutatingAdmissionPolicy and its binding to the ConfigMaps:

kyverno apply /path/to/add-label-to-configmap.yaml --resource /path/to/configmaps.yaml -f /path/to/values.yaml

The output will show the mutated ConfigMaps in the staging and production Namespaces, while the one in the testing Namespace remains unchanged:

Applying 1 policy rule(s) to 3 resource(s)...

policy add-label-to-configmap applied to staging/ConfigMap/matched-cm-1:
apiVersion: v1
data:
  player_initial_lives: "3"
kind: ConfigMap
metadata:
  labels:
    color: red
    lfx-mentorship: kyverno
  name: matched-cm-1
  namespace: staging
---

Mutation has been applied successfully.
policy add-label-to-configmap applied to production/ConfigMap/matched-cm-2:
apiVersion: v1
data:
  player_initial_lives: "3"
kind: ConfigMap
metadata:
  labels:
    color: red
    lfx-mentorship: kyverno
  name: matched-cm-2
  namespace: production
---

Mutation has been applied successfully.
pass: 2, fail: 0, warn: 0, error: 0, skip: 0

Applying ValidatingPolicies

In this example, we will apply a ValidatingPolicy against two Deployment manifests: one that complies with the policy and one that violates it.

First, we define a ValidatingPolicy that ensures any Deployment has no more than two replicas.

Policy manifest (check-deployment-replicas.yaml):

apiVersion: policies.kyverno.io/v1alpha1
kind: ValidatingPolicy
metadata:
  name: check-deployment-replicas
spec:
  matchConstraints:
    resourceRules:
      - apiGroups: ['apps']
        apiVersions: ['v1']
        operations: ['CREATE', 'UPDATE']
        resources: ['deployments']
  validations:
    - expression: 'object.spec.replicas <= 2'
      message: 'Deployment replicas must be less than or equal to 2'

Next, we have two Deployment manifests. The good-deployment is compliant with 2 replicas, while the bad-deployment is non-compliant with 3 replicas.

Resource manifest (deployments.yaml):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: good-deployment
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:latest
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: bad-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:latest

Now, we use the kyverno apply command to test the policy against both resources.

kyverno apply /path/to/check-deployment-replicas.yaml --resource /path/to/deployments.yaml --policy-report

The following output will be generated:

apiVersion: openreports.io/v1alpha1
kind: ClusterReport
metadata:
  creationTimestamp: null
  name: merged
results:
- message: Deployment replicas must be less than or equal 2
  policy: check-deployment-replicas
  properties:
    process: background scan
  resources:
  - apiVersion: apps/v1
    kind: Deployment
    name: bad-deployment
    namespace: default
  result: fail
  scored: true
  source: KyvernoValidatingPolicy
  timestamp:
    nanos: 0
    seconds: 1752755472
- message: success
  policy: check-deployment-replicas
  properties:
    process: background scan
  resources:
  - apiVersion: apps/v1
    kind: Deployment
    name: good-deployment
    namespace: default
  result: pass
  scored: true
  source: KyvernoValidatingPolicy
  timestamp:
    nanos: 0
    seconds: 1752755472
source: ""
summary:
  error: 0
  fail: 1
  pass: 1
  skip: 0
  warn: 0

In addition to testing local YAML files, you can use the kyverno apply command to validate policies against resources that are already running in a Kubernetes cluster. Instead of specifying resource files with the --resource flag, you can use the --cluster flag.

For example, to test the check-deployment-replicas policy against all Deployment resources in your currently active cluster, you would run:

kyverno apply /path/to/check-deployment-replicas.yaml --cluster --policy-report

Many advanced policies need to look up the state of other resources in the cluster using Kyverno’s custom CEL functions like resource.Get(). When testing such policies locally with the kyverno apply command, the CLI cannot connect to the cluster to retrieve the required resources so you have to provide these resources as input via the --context-path flag.

This flag allows you to specify the resources that the policy will reference. The CLI will then use these resources to evaluate the policy.

This example demonstrates how to test a policy that validates an incoming Pod by checking its name against a value stored in a ConfigMap.

First, we define a ValidatingPolicy that uses resource.Get() to fetch a ConfigMap named policy-cm. The policy then validates that the incoming Pod’s name matches the name key in the ConfigMap’s data.

Policy manifest (check-pod-name-from-configmap.yaml):

apiVersion: policies.kyverno.io/v1alpha1
kind: ValidatingPolicy
metadata:
  name: check-pod-name-from-configmap
spec:
  matchConstraints:
    resourceRules:
      - apiGroups: ['']
        apiVersions: ['v1']
        operations: ['CREATE', 'UPDATE']
        resources: ['pods']
  variables:
    # This variable uses a Kyverno CEL function to get a ConfigMap from the cluster.
    - name: cm
      expression: >-
        resource.Get("v1", "configmaps", object.metadata.namespace, "policy-cm")
  validations:
    # This rule validates that the Pod's name matches the 'name' key in the ConfigMap's data.
    - expression: >-
        object.metadata.name == variables.cm.data.name

Next, we define two Pod manifests: good-pod, which should pass the validation, and bad-pod, which should fail.

Resource manifest (pods.yaml):

apiVersion: v1
kind: Pod
metadata:
  name: good-pod
spec:
  containers:
    - name: nginx
      image: nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: bad-pod
spec:
  containers:
    - name: nginx
      image: nginx

Because the CLI cannot connect to a cluster to fetch the policy-cm ConfigMap, we must provide it in a context file. This file contains a mock ConfigMap that resource.Get() will use during local evaluation.

Context file (context.yaml):

apiVersion: cli.kyverno.io/v1alpha1
kind: Context
metadata:
  name: context
spec:
  # The resources defined here will be available to functions like resource.Get()
  resources:
    - apiVersion: v1
      kind: ConfigMap
      metadata:
        namespace: default
        name: policy-cm
      data:
        # According to this, the valid pod name is 'good-pod'.
        name: good-pod

Now, we can run the kyverno apply command, providing the policy, the resources, and the context file. We also use the -p (or --policy-report) flag to generate a ClusterReport detailing the results.

kyverno apply /path/to/policy.yaml --resource /path/to/pods.yaml --context-file /path/to/context.yaml -p

The following output will be generated:

apiVersion: openreports.io/v1alpha1
kind: ClusterReport
metadata:
  creationTimestamp: null
  name: merged
results:
  - message: success
    policy: check-pod-name-from-configmap
    properties:
      process: background scan
    resources:
      - apiVersion: v1
        kind: Pod
        name: good-pod
        namespace: default
    result: pass
    scored: true
    source: KyvernoValidatingPolicy
    timestamp:
      nanos: 0
      seconds: 1752756617
  - policy: check-pod-name-from-configmap
    properties:
      process: background scan
    resources:
      - apiVersion: v1
        kind: Pod
        name: bad-pod
        namespace: default
    result: fail
    scored: true
    source: KyvernoValidatingPolicy
    timestamp:
      nanos: 0
      seconds: 1752756617
source: ''
summary:
  error: 0
  fail: 1
  pass: 1
  skip: 0
  warn: 0

• The good-pod resource resulted in a pass because its name matches the value in the ConfigMap provided by the context file.

• The bad-pod resource resulted in a fail because its name does not match, and the report includes the validation error message from the policy.

When using the --cluster flag, the CLI connects to your active Kubernetes cluster, so a local context file is not needed. The resource.Get() function will fetch the live ConfigMap directly from the cluster so you have to ensure the ConfigMap and the Pod resources exist in your cluster before running the command.

kyverno apply /path/to/check-pod-name-from-configmap.yaml --cluster --policy-report

In case of applying a ValidatingPolicy with a PolicyException, you can use the --exception flag to specify the exception manifest. The CLI will then apply the policy and the exception together.

In this example, we will test a policy that disallows hostPath volumes, but we will use a PolicyException to create an exemption for a specific Pod.

Policy manifest (disallow-host-path.yaml):

apiVersion: policies.kyverno.io/v1alpha1
kind: ValidatingPolicy
metadata:
  name: disallow-host-path
spec:
  matchConstraints:
    resourceRules:
      - apiGroups: ['']
        apiVersions: ['v1']
        operations: ['CREATE', 'UPDATE']
        resources: ['pods']
  validations:
    - expression: '!has(object.spec.volumes) || object.spec.volumes.all(volume, !has(volume.hostPath))'
      message: 'HostPath volumes are forbidden. The field spec.volumes[*].hostPath must be unset.'

Next, we define a Pod that clearly violates this policy by mounting a hostPath volume. Without an exception, this Pod would be blocked.

Resource manifest (pod-with-hostpath.yaml):

apiVersion: v1
kind: Pod
metadata:
  name: pod-with-hostpath
spec:
  containers:
    - name: nginx
      image: nginx
  volumes:
    - name: udev
      hostPath:
        path: /etc/udev

Now, we create a PolicyException to exempt our specific Pod from this policy. The exception matches the Pod by name and references the disallow-host-path policy.

Policy Exception manifest (exception.yaml):

apiVersion: policies.kyverno.io/v1alpha1
kind: PolicyException
metadata:
  name: exempt-hostpath-pod
spec:
  policyRefs:
    - name: disallow-host-path
      kind: ValidatingPolicy
  matchConditions:
    - name: 'skip-pod-by-name'
      expression: "object.metadata.name == 'pod-with-hostpath'"

Now, we use the kyverno apply command, providing the policy, the resource, and the exception using the --exception flag. We will also use -p to generate a detailed report.

kyverno apply policy.yaml --resource resource.yaml --exception exception.yaml -p

The following output will be generated:

apiVersion: openreports.io/v1alpha1
kind: ClusterReport
metadata:
  creationTimestamp: null
  name: merged
results:
  - message: 'rule is skipped due to policy exception: exempt-hostpath-pod'
    policy: disallow-host-path
    properties:
      exceptions: exempt-hostpath-pod
      process: background scan
    resources:
      - apiVersion: v1
        kind: Pod
        name: pod-with-hostpath
        namespace: default
    result: skip
    rule: exception
    scored: true
    source: KyvernoValidatingPolicy
    timestamp:
      nanos: 0
      seconds: 1752759828
source: ''
summary:
  error: 0
  fail: 0
  pass: 0
  skip: 1
  warn: 0

The output confirms that the PolicyException worked as intended:

• result: skip: The policy rule was not enforced on the resource.

• properties.exceptions: exempt-hostpath-pod: The report explicitly names the PolicyException responsible for the skip.

• summary.skip: 1: The final count reflects that one rule was skipped.