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Concepts

Open Policy Agent in Vim: Write, Test, and Enforce Policies Without Leaving Your Editor

Andrios Robert

• 1 min read

Open Policy Agent (OPA) is the leading open-source engine for enforcing fine-grained, programmable policies across microservices, Kubernetes, APIs, and CI/CD pipelines. When paired with Vim, OPA lets you write, test, and iterate on Rego policies without leaving your editing flow. No switching tabs. No breaking concentration.

Why OPA in Vim

OPA policies are written in Rego, a declarative language built for evaluating structured data like JSON. Rego is powerful but strict, making real-time feedback crucial. With Vim integration, you can:

  • Run opa eval on current buffers
  • Validate policy syntax instantly
  • Autofold and navigate complex Rego blocks with ease
  • Connect to live datasets for rapid policy prototyping

This tight loop speeds up development and catches errors early. It turns policy into code you can shape as quickly as any function or config.

Setting Up OPA in Vim

Install OPA CLI from GitHub or your package manager. Add Vim plugins that support Rego syntax highlighting, such as vim-rego. Configure Vim to map keys for opa eval commands. With a few lines in .vimrc, you can trigger policy evaluation against JSON input from within your editor.

Example workflow:

  1. Write Rego rules in a .rego file.
  2. Open the file in Vim.
  3. Use mapped commands to run OPA against sample input.
  4. Inspect results, fix issues, retest—all inside Vim.

Advanced Uses

Integrate OPA-Vim workflows into your build or deployment scripts. Link policy evaluation to your Makefile or test suite. Tie in Kubernetes manifests, Terraform plans, or API responses. The goal is one keystroke from code to compliance.

Why It Matters

Security, compliance, and access control are now standard parts of software delivery. Embedding OPA in Vim cuts the friction from writing and enforcing these rules. Your policies stay versioned, testable, and ready for automation.

Fast policy loops mean fewer errors in production. It means knowing exactly what rules run in your system and verifying them before they ship.

Write your policies where you write your code. Make OPA part of your Vim muscle memory.

See it live with hoop.dev—connect OPA, edit in Vim, and get instant feedback in minutes.