OPA Gatekeeper Policy Configuration

Describes configuration of policies using Open Policy Agent (OPA) Gatekeeper, a Rego-based policy engine implemented in HPE Ezmeral Runtime Enterprise as an admission controller for Kubernetes clusters.

HPE Ezmeral Runtime Enterprise leverages OPA Gatekeeper as an admission controller to validate and enforce policies on the cluster. OPA Gatekeeper is installed as a mandatory system add-on, which is automatically created for HPE Ezmeral Runtime Enterprise users. For more information about OPA Gatekeeper, see the official OPA Gatekeeper documentation (link opens an external website in a new browser tab or window).

This feature is not available in HPE Ezmeral Runtime Enterprise Essentials.

You can use Centralized Policy Management to define and manage OPA Gatekeeper policies stored in a Git repository, and apply them to clusters managed by HPE Ezmeral Runtime Enterprise. For information, see Centralized Policy Management.

Default OPA Policies for Kubernetes Clusters

HPE Ezmeral Runtime Enterprise automatically configures default policies on Kubernetes clusters. Use the kubectl get constraints command to list all default policies.

NOTE To ensure that KubeDirector applications function as expected, HPE Ezmeral Runtime Enterprise automatically configures some default policies as dry run. HPE Ezmeral Runtime Enterprise does not enforce these policies, but lists workloads which violate them in the Violations tab. For more information on viewing policy violations, see Viewing Policy Violations.

The following default policies are configured as dry run:

psp-non-root-user-and-group
psp-host-network-ports
psp-host-filesystem

Default policies are as follows:

The psp-privileged-container policy ensures that privileged workloads run only in reserved (system) namespaces.
```
k8spspprivilegedcontainer.constraints.gatekeeper.sh/psp-privileged-container
```
The psp-non-root-user-and-group policy ensures pods with nonroot user and group run only in reserved (system) namespaces.
```
k8spspnonrootuserandgroup.constraints.gatekeeper.sh/psp-non-root-user-and-group
```
The psp-host-network-ports policy ensures pods that use host network and host port run only in reserved (system) namespaces.
```
k8spsphostnetworkingports.constraints.gatekeeper.sh/psp-host-network-ports
```
The psp-host-filesystem policy ensures pods that use host file system run only in reserved (system) namespaces.
```
k8spsphostfilesystem.constraints.gatekeeper.sh/psp-host-filesystem
```

Creating OPA Policies

Create OPA Gatekeeper policies with Rego policy language, as described in Rego Policy Language.

For information and tutorials on using OPA Gatekeeper with Kubernetes, see the official OPA Gatekeeper documentation (link opens an external website in a new browser tab or window).

Applying, Modifying, and Deleting OPA Policies

Apply, modify, and delete OPA Gatekeeper policies, including default policies, as follows:

After you have created a policy with Rego, apply the constraint and template objects on a Kubernetes cluster as follows. On the Kubernetes master node enter the commands:
```
kubectl apply -f constraint_template.yaml
```
```
kubectl apply -f constraint.yaml
```
To modify a policy, update the constraint object associated with the policy with the following command:
```
kubectl edit constraint.yaml
```
To delete a policy, use the following command:
```
kubectl delete constraint.yaml
```