Managing Dependencies with Yarn PnP: To Commit or Not to Commit the `.yarn` Folder?

When adopting Yarn Plug'n'Play (PnP) for your project, you'll soon encounter a decision point: should you commit the .yarn folder to your Git repository? This folder is central to Yarn's approach to handling dependencies, potentially including the Yarn release itself, some configuration files, and a cache of your project's dependencies. Let's break down the considerations to help you make an informed decision.

Reproducibility

Committing the .yarn folder, specifically the releases and plugins subdirectories, ensures that all developers and your CI/CD pipeline use the exact same Yarn version with identical configurations. This level of consistency is crucial for avoiding the infamous "works on my machine" problem.

Zero-installs

Yarn's Zero-Installs feature aims to eliminate the need for running yarn install when cloning a repository. By committing the .yarn/cache folder, project setup times for new developers and CI/CD pipelines can be significantly reduced. However, this convenience comes at the cost of increasing your repository's size.

Project Size and Clutter

The primary downside of including the .yarn folder in your repository, especially the cache, is the potential for bloating your project's size. This might not be suitable for every team, especially if keeping the repository lean is a priority.

Security Considerations

Committing your dependencies directly to your repository allows for easier auditing and security checks, giving you more control over the third-party code you're utilizing. Nonetheless, this approach requires diligence in updating these dependencies to mitigate vulnerabilities.

Best Practices

• Consistency: Always commit the .yarn/releases and .yarn/plugins directories to ensure Yarn behaves consistently across environments.
• Decision Making: Base your decision to commit the .yarn/cache directory on your project's specific needs and team preferences.
• Exclusions: If opting not to commit the .yarn/cache folder, ensure it's listed in your .gitignore file to prevent accidental commits.
• Configuration: Keep your .yarnrc.yml file in the repository to maintain consistent Yarn behavior for all users.

In summary, the choice to commit the .yarn folder to your Git repository hinges on balancing reproducibility and convenience against the drawbacks of increased repository size. While it's generally advisable to include at least parts of the .yarn folder for consistent Yarn performance, the final decision should reflect your team's specific needs and priorities.