OPA Gatekeeper for Kubernetes is a customizable admission webhook for Kubernetes that enforces policies executed by the Open Policy Agent (OPA). We're using this extension of the Kubernetes platform to add a security layer to clusters, providing automated governance mechanisms that ensure applications are compliant with defined policies. Our teams like it because of its customization capability; using CustomResourceDefinitions (CRD) allows us to define ConstraintTemplates and Constraints which make defining rules and the objects (e.g., deployments, jobs, cron jobs) and namespaces under evaluation an easy task.