implementing-policy-as-code-with-open-policy-agent

# Implementing Policy as Code with Open Policy Agent ## When to Use - When enforcing organizational security policies across Kubernetes clusters programmatically - When requiring admission control that blocks non-compliant resources from being created - When implementing policy governance that can be version-controlled, tested, and audited - When standardizing security rules across multiple clusters and environments - When needing a flexible policy engine that extends beyond Kubernetes to APIs and CI/CD **Do not use** for vulnerability scanning (use Trivy/Checkov), for runtime threat detection (use Falco), or for network policy enforcement (use Kubernetes NetworkPolicy or Calico). ## Prerequisites - Kubernetes cluster with admin access for Gatekeeper installation - Helm for Gatekeeper deployment - OPA CLI or conftest for local policy testing - Rego knowledge for policy authoring ## Workflow ### Step 1: Install OPA Gatekeeper ```bash # Install Gatekeeper via Helm helm repo add gatekeeper https://open-policy-agent.github.io/gatekeeper/charts helm install gatekeeper gatekeeper/gatekeeper \ --namespace gatekeeper-system --create-namespace \ --set replicas=3 \ --set audit.replicas=1 \ --set audit.writeToRAMDisk=true ``` ### Step 2: Create Constraint Templates ```yaml # templates/k8s-required-labels.yaml apiVersion: templates.gatekeeper.sh/v1 kind: ConstraintTemplate metadata: name: k8srequiredlabels spec: crd: spec: names: kind: K8sRequiredL...