Configuration Policy

The ConfigurationPolicy defines Kubernetes manifests to compare with objects that currently exist on the cluster. The Configuration policy controller is provided by Open Cluster Management and runs on managed clusters.

Prerequisites

You must meet the following prerequisites to install the configuration policy controller:

• Ensure kubectl and kustomize are installed.

• Ensure Golang is installed, if you are planning to install from the source.

• Ensure the open-cluster-management policy framework is installed. See Policy Framework for more information.

Installing the configuration policy controller

Deploy via Clusteradm CLI

Ensure clusteradm CLI is installed and is newer than v0.3.0. Download and extract the clusteradm binary. For more details see the clusteradm GitHub page.

1. Deploy the configuration policy controller to the managed clusters (this command is the same for a self-managed hub):

   # Deploy the configuration policy controller
   clusteradm addon enable addon --names config-policy-controller --clusters <cluster_name> --context ${CTX_HUB_CLUSTER}
   

2. Ensure the pod is running on the managed cluster with the following command:

   $ kubectl get pods -n open-cluster-management-agent-addon
   NAME                                               READY   STATUS    RESTARTS   AGE
   config-policy-controller-7f8fb64d8c-pmfx4          1/1     Running   0          44s
   

Sample configuration policy

After a successful deployment, test the policy framework and configuration policy controller with a sample policy.

For more information on how to use a ConfigurationPolicy, read the Policy API concept section.

1. Run the following command to create a policy on the hub that uses Placement:

   # Configure kubectl to point to the hub cluster
   kubectl config use-context ${CTX_HUB_CLUSTER}
   
   # Apply the example policy and placement
   kubectl apply -n default -f https://raw.githubusercontent.com/open-cluster-management-io/policy-collection/main/community/CM-Configuration-Management/policy-pod-placement.yaml
   

2. Update the Placement to distribute the policy to the managed cluster with the following command (this clusterSelector will deploy the policy to all managed clusters):

   kubectl patch -n default placement.cluster.open-cluster-management.io/placement-policy-pod --type=merge -p "{\"spec\":{\"predicates\":[{\"requiredClusterSelector\":{\"labelSelector\":{\"matchExpressions\":[]}}}]}}"
   

3. Make sure the default namespace has a ManagedClusterSetBinding for a ManagedClusterSet with at least one managed cluster resource in the ManagedClusterSet. See Bind ManagedClusterSet to a namespace for more information on this.

4. To confirm that the managed cluster is selected by the Placement, run the following command:

   $ kubectl get -n default placementdecision.cluster.open-cluster-management.io/placement-policy-pod-decision-1 -o yaml
   ...
   status:
     decisions:
     - clusterName: <managed cluster name>
       reason: ""
   ...
   

5. Enforce the policy to make the configuration policy automatically correct any misconfigurations on the managed cluster:

   $ kubectl patch -n default policy.policy.open-cluster-management.io/policy-pod --type=merge -p "{\"spec\":{\"remediationAction\": \"enforce\"}}"
   policy.policy.open-cluster-management.io/policy-pod patched
   

6. After a few seconds, your policy is propagated to the managed cluster. To confirm, run the following command:

   $ kubectl config use-context ${CTX_MANAGED_CLUSTER}
   $ kubectl get policy -A
   NAMESPACE   NAME                 REMEDIATION ACTION   COMPLIANCE STATE   AGE
   cluster1    default.policy-pod   enforce              Compliant          4m32s
   

7. The missing pod is created by the policy on the managed cluster. To confirm, run the following command on the managed cluster:

   $ kubectl get pod -n default
   NAME               READY   STATUS    RESTARTS   AGE
   sample-nginx-pod   1/1     Running   0          23s