The rules had changed, but no one told the system.

Open Policy Agent (OPA) is the control plane for policy enforcement. In Site Reliability Engineering (SRE), OPA becomes the single source of truth for decisions. Instead of scattering logic across services, you centralize it. Your infrastructure, deployments, and pipelines check policy once, in one place, every time.

OPA runs as a lightweight agent or sidecar, evaluating policies written in Rego. Rego is built for structured data like JSON, making it simple to define access controls, compliance checks, and operational safeguards. You can integrate it with Kubernetes Admission Controllers, CI/CD workflows, API gateways, or custom microservices. The policy stays abstracted from application code, allowing engineers to update rules without redeploying the system.

For SRE teams, this means enforcing operational standards at scale. Whether it’s controlling who can trigger a production deploy, blocking unsafe configuration changes, or validating infrastructure manifests before they hit production, OPA executes these checks with millisecond latency. It integrates via REST API or SDKs in multiple languages, and can run embedded or as a remote service.

OPA and SRE share the same objective: reliability through control. With policy-as-code, you track every change in version control, unit test your rules, and roll out updates with the same rigor as application code. Automated enforcement removes human error from high-risk actions, improving uptime and incident response.

This approach works across environments—local dev, staging, cloud, hybrid. It is vendor-neutral, open source, and proven in production at scale. For teams that want consistent governance without slowing delivery, it’s the missing link between engineering speed and operational safety.

Ready to see OPA in action as part of a modern SRE workflow? Try it live with hoop.dev and deploy your first policy in minutes.