What does GitHub Codeowners do?

Amaresh Pelleti

As a Git enthusiast and developer who’s worked with numerous teams, I’ve discovered that the CODEOWNERS file is one of GitHub’s most underrated features. Let me break down what it is and why you should be using it in your projects.

What is CODEOWNERS?

Think of CODEOWNERS as your repository’s bouncer – it automatically assigns reviewers to pull requests based on which files are being changed. Pretty neat, right? I remember when our team first implemented it; it eliminated the constant “Who should review this?” questions in our Slack channels.

Why Should You Care?

Before we dive into the technical details, here’s why CODEOWNERS matters:

  • No more confusion about who should review what
  • Automatic reviewer assignment
  • Better code ownership accountability
  • Faster code review process
  • Improved security for critical code

Setting Up CODEOWNERS

Creating a CODEOWNERS file is straightforward. Here’s how I do it:

  1. Create a new file named CODEOWNERS in either:
  • The root directory
  • The .github/ directory
  • The docs/ directory
  1. Use the following syntax to specify owners:
# Example of CODEOWNERS file
# Syntax: file-pattern owner1 owner2

# Default owners for everything
* @global-owner1 @global-owner2

# Frontend team owns all JS files
*.js @frontend-team

# Backend team owns all Python files
*.py @backend-team

Real-World Examples

Let me share some practical examples I’ve used in my projects:

Example 1: Simple Team Structure

# Documentation
/docs/* @technical-writers

# Frontend
/src/components/* @frontend-team
/src/styles/* @design-team

# Backend
/server/* @backend-team

Example 2: Multiple Owners

# Security-sensitive files need both security and backend team review
/security/* @security-team @backend-team

# Config files need DevOps and tech lead review
*.config.js @devops-team @tech-lead

Pro Tips from My Experience

  1. Start Simple: Begin with basic patterns and expand as needed. I learned this the hard way after initially creating overly complex rules.
  2. Use Team Handles: Instead of individual usernames, use team handles like @frontend-team. This makes maintenance much easier when team members change.
  3. Document Patterns: Add comments explaining complex patterns. Your future self will thank you!
# Matches all files in src/lambda and its subdirectories
/src/lambda/** @serverless-team

# Matches package.json in the root and all subdirectories
package.json @dependency-reviewers

Common Gotchas

Through trial and error, I’ve discovered these important points:

  1. Order Matters: The last matching pattern takes precedence. Always put more specific patterns after general ones.
  2. Case Sensitivity: File patterns are case-sensitive on case-sensitive file systems.
  3. Path Format: Always use forward slashes (/) even on Windows.

Best Practices

Based on my experience managing multiple repositories, here are my recommended best practices:

  1. Review Regularly: Update your CODEOWNERS file as team structures change.
  2. Don’t Over-Assign: Avoid assigning too many owners to a single pattern.
  3. Use Wildcards Wisely: Be careful with patterns like * – they can accidentally match more files than intended.

Conclusion

CODEOWNERS is like having a smart assistant that knows exactly who should review what code. It’s transformed how my teams handle code reviews, making the process more efficient and less prone to confusion.

Remember, the goal isn’t to create a complex web of ownership but to establish clear, maintainable patterns that help your team work better together.

Have you implemented CODEOWNERS in your projects? I’d love to hear about your experiences in the comments below!