Kubernetes allows users to define and deploy resources using code, but lacks inherent mechanisms to validate these configurations for errors or security issues. Open Policy Agent (OPA) provides a solution by enabling the definition and enforcement of policies through code, using a language called Rego, to ensure that Kubernetes resource definitions meet specific criteria. OPA can be deployed in Kubernetes using either sidecar containers or the Gatekeeper add-on, with Gatekeeper offering a more seamless integration by using custom resource definitions. This allows for scalable policy evaluations and centralized policy management, enhancing security and compliance. OPA policies, once set up, automatically validate resource configurations during deployment to prevent violations, such as missing memory limits or unapproved container registries. Moreover, the integration of OPA with tools like groundcover enhances Kubernetes observability and troubleshooting capabilities, providing comprehensive assurance for resource configuration and performance monitoring.