regal

Regal

Regal is a linter, debugger and language server for Rego, making your Rego magnificent, and you the ruler of rules!

With its extensive set of linter rules, documentation and editor integrations, Regal is the perfect companion for policy development, whether you're an experienced Rego developer or just starting out.

regal

adj : of notable excellence or magnificence : splendid

- Merriam Webster

Goals

• Deliver an outstanding policy development experience by providing the best possible tools for that purpose
• Identify common mistakes, bugs and inefficiencies in Rego policies, and suggest better approaches
• Provide advice on best practices, coding style, and tooling
• Allow users, teams and organizations to enforce custom rules on their policy code

What People Say About Regal

I really like that at each release of Regal I learn something new! Of all the linters I'm exposed to, Regal is probably the most instructive one.

— Leonardo Taccari, NetBSD

Reviewing the Regal rules documentation. Pure gold.

— Dima Korolev, Miro

Such an awesome project!

— Shawn McGuire, Atlassian

I am really impressed with Regal. It has helped me write more expressive and deterministic Rego.

— Jimmy Ray, Boeing

See the adopters file for more Regal users.

Getting Started

Download Regal

# macOS
brew install regal

# linux x86
curl -L -o regal https://github.com/open-policy-agent/regal/releases/latest/download/regal_Linux_x86_64
chmod 755 ./regal

# windows
Invoke-WebRequest -Uri "https://github.com/open-policy-agent/regal/releases/latest/download/regal_Windows_x86_64.exe" -OutFile "regal.exe"

curl -L -o regal "https://github.com/open-policy-agent/regal/releases/latest/download/regal_Darwin_arm64"

curl -L -o regal "https://github.com/open-policy-agent/regal/releases/latest/download/regal_Darwin_x86_64"

curl -L -o regal "https://github.com/open-policy-agent/regal/releases/latest/download/regal_Linux_arm64"
chmod 755 ./regal

docker pull ghcr.io/open-policy-agent/regal:latest

Try it out!

First, author some Rego!

package authz

default allow = false

allow if {
    isEmployee
    "developer" in input.user.roles
}

isEmployee if regex.match("@acmecorp\\.com$", input.user.email)

Next, run regal lint pointed at one or more files or directories to have them linted.

regal lint policy/

Rule:         	non-raw-regex-pattern
Description:  	Use raw strings for regex patterns
Category:     	idiomatic
Location:     	policy/authz.rego:12:27
Text:         	isEmployee if regex.match("@acmecorp\\.com$", input.user.email)
Documentation:	https://www.openpolicyagent.org/projects/regal/rules/idiomatic/non-raw-regex-pattern

Rule:         	use-assignment-operator
Description:  	Prefer := over = for assignment
Category:     	style
Location:     	policy/authz.rego:5:1
Text:         	default allow = false
Documentation:	https://www.openpolicyagent.org/projects/regal/rules/style/use-assignment-operator

Rule:         	prefer-snake-case
Description:  	Prefer snake_case for names
Category:     	style
Location:     	policy/authz.rego:12:1
Text:         	isEmployee if regex.match("@acmecorp\\.com$", input.user.email)
Documentation:	https://www.openpolicyagent.org/projects/regal/rules/style/prefer-snake-case

1 file linted. 3 violations found.

Note If you're running Regal on an existing policy library, you may want to disable the style category initially, as it will likely generate a lot of violations. You can do this by passing the --disable-category style flag to regal lint.

Using Regal in Your Editor

Linting from the command line is a great way to get started with Regal, and even for some experienced developers the preferred way to work with the linter. However, not only is Regal a linter, but a full-fledged development companion for Rego development!

Integrating Regal in your favorite editor means you'll get immediate feedback from the linter as you work on your policies. More than that, it'll unlock a whole new set of features that leverage Regal's language server, like context-aware completion suggestions, informative tooltips on hover, or go-to-definition.

Elevate your policy development experience with Regal in VS Code, Neovim, Zed, Helix and more on our Editor Support page!

To learn more about the features provided by the Regal language server, see the Language Server page.

Using Regal in Your Build Pipeline

To ensure Regal's rules are enforced consistently in your project or organization, we've made it easy to run Regal as part of your builds. See the docs on Using Regal in your build pipeline to learn more about how to set up Regal to lint your policies on every commit or pull request.

Next Steps

Now that you're up and running with Regal, take a look around some of our documentation to get a feel for the different features and capabilities of Regal.

• Rules
  • Bugs: Common mistakes, potential bugs and inefficiencies in Rego policies.
  • Idiomatic: Suggestions for more idiomatic constructs.
  • Imports: Best practices for imports.
  • Performance: Rules for improving performance of policies.
  • Style: Rego Style Guide rules.
  • Testing: Rules for testing and development.
  • Custom: Custom rules where enforcement can be adjusted to match your preferences.
• Configuration: Dig into some of the different configuration options available.
• Editor Support: Get Regal integrated into your editor of choice.
  • Language Server: Learn more about Regal's advanced editor capabilities.
  • DAP: Live debug your Rego policies with Regal's DAP support.
• Fixing Issues: See Regal can help you fix issues in your Rego policies automatically.
• CI/CD: Run Regal as part of your automated checks.
• Custom Rules: Learn how to write your own rules for Regal.
• Adopters: See who else is using Regal.

Learn More

Documentation

Please see Regal's Documentation Site for the canonical documentation of Regal.

Contributing contains information about how to hack on Regal itself.

Talks

• OPA Maintainer Track, featuring Regal, KubeCon London, 2025
• Regal the Rego Linter, CNCF London meetup, June 2023

Blogs and Articles

• Guarding the Guardrails - Introducing Regal the Rego Linter by Anders Eknert (@anderseknert)
• Scaling Open Source Community by Getting Closer to Users by Charlie Egan (@charlieegan3)
• Renovating Rego by Anders Eknert (@anderseknert)
• Linting Rego with... Rego! by Anders Eknert (@anderseknert)
• Regal: Rego(OPA)用リンタの導入手順 by Jun Fujita (@erueru-tech)
• Regal を使って Rego を Lint する by Shibata Takao (@shibata.takao)

Status

Regal is currently in beta. End-users should not expect any drastic changes, but any API may change without notice. If you want to embed Regal in another project or product, please reach out!

Roadmap

The current Roadmap items are all related to the preparation for Regal 1.0:

• Go API: Refactor the Location object in Violation (#1554)
• Rego API: Provide a stable and well-documented Rego API (#1555)
• Go API: Audit and reduce the public Go API surface (#1556)
• Custom Rules: Tighten up Authoring experience (#1559)
• docs: Improve automated documentation generation (#1557)
• docs: Break down README into smaller units (#1558)
• lsp: Support a JetBrains LSP client (#1560)

If there's something you'd like to have added to the roadmap, either open an issue, or reach out in the community Slack!