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Concepts

Self-Hosting Open Policy Agent: A Complete Guide

Andrios Robert

• 2 min read

The container is running, the port is open, and OPA is ready to parse every decision your system needs. Self-hosting Open Policy Agent is not complicated, but it demands precision. Done right, it gives you complete control over policy enforcement without relying on external services.

What is Open Policy Agent (OPA)?

OPA is a general-purpose policy engine. It decouples policy from application logic, letting you define rules in Rego and evaluate them at runtime. You can enforce access control, configuration validation, resource restrictions, or any decision that needs consistency and auditability.

Why Self-Host OPA?

Self-hosting ensures your policy decisions stay inside your infrastructure. You avoid third-party costs and latency. You can integrate OPA directly with Kubernetes, microservices, API gateways, or bare-metal applications. Control is absolute—deployment patterns, scaling methods, and security boundaries stay in your hands.

Core Steps for OPA Self-Hosted Deployment

  1. Select Deployment Target
    You can run OPA on a VM, in Docker containers, or as a sidecar in Kubernetes. Choose based on workload isolation and scaling requirements.
  2. Define Your Policies
    Create .rego files that hold your rules. Structure them by API endpoint, resource type, or service domain.
  3. Integrate with Your Application
    Applications send JSON input to OPA’s API and receive decision output. Use local caching if performance is critical.
  4. Secure and Monitor
    Restrict OPA’s API with TLS. Monitor metrics via Prometheus integration. Keep policy files in version control for audits.

Run OPA as a Service
For a persistent container:

docker run -p 8181:8181 \
--name opa \
-v $(pwd):/policies \
openpolicyagent/opa:latest \
run --server /policies

This exposes OPA’s REST API on port 8181 for policy queries.

Download and Install OPA
For Docker:

docker pull openpolicyagent/opa:latest

Or install a binary from GitHub releases for bare-metal.

Best Practices

  • Keep policies modular and reusable.
  • Automate deployment with CI/CD so policies publish alongside code.
  • Test policy changes in staging before pushing to production.
  • Document rules so new team members understand decision paths.

Scaling OPA

Horizontal scaling works by running multiple OPA instances behind a load balancer. In Kubernetes, deploy OPA as a DaemonSet or sidecar container per pod. For high throughput, store policies in distributed storage and mount them into each OPA instance.

Self-hosted Open Policy Agent gives you predictable performance, data locality, and total autonomy over policy enforcement. The setup is clear, but the benefits run deep.

Spin up OPA inside your system and watch decisions happen instantly. Try it with hoop.dev—see it live in minutes and control your policies your way.