Discussion of the Benefits and Drawbacks of the Git Pre-Commit Hook

Summary

The Git pre-commit hook is a commonly used tool for automated quality assurance in the contribution process to software projects. It is run by default when a user creates a commit and prevents the commit from being created if it fails, i.e. exits with a non-zero exit code. Setting up a pre-commit hook is as simple as putting a script named pre-commit into the .git/hooks folder. The pre-commit hook can be a powerful tool, since it is the last chance to prevent sensitive information from being tracked by version control, which can be difficult to clean up if it is noticed too late. This text does not concern itself with the pre-receive hook or other Git hooks, for which different benefits and drawbacks might be true. It is only focused on the pre-commit hook, since it is the most widely used hook and the one I was recently confronted with. Using the Pre-Commit HookSince the hooks folder is not part of Git’s version control, setting up the pre-commit hook is not trivial to do for new contributors to a project and requires some tools to set up easily. There are various tools for this - Pre-Commit is a standalone tool, Prek is a work-in-progress Rust re-engineering of Pre-Commit, and Husky requires Node.js and npm and supports other Git hooks as well. Pre-Commit includes dependency management of hooks, which are written and packaged for it. Common quality assurance tools like Gitleaks, ESLint or Nixfmt include a manifest with a configuration for Pre-Commit, which makes them installable with it. Husky relies on users using npm to install it and any other dependencies, and its hooks are predominantly written in JavaScript/TypeScript. It is more of an ecosystem-internal solution than a tool for software projects in general. Without external tools, a common and simple way to set up hooks and to track the hooks in Git’s version control is to create symlinks from the hooks folder to the repository with something like ln -s $(pwd)/scripts/pre-commit .git/hooks/pre-commit. The s...