The days when a single piece of software, relied on by millions, was created by a single developer off in an ivory tower are long gone. Even Git, universally believed to be the brainchild of Linus Torvalds alone, was created with the help of a number of contributors and is now being maintained by a team of dozens.
No matter if you’re working on an open source project with the whole world as your oyster, or if you’re “blooming” in a walled garden of proprietary commercial software—you’re still working on a team. And even with a well-organized system of pull requests and code reviews, maintaining the code quality across a large codebase with dozens of contributors is not an easy task.
Hook me up
Hooks—a method of firing off custom scripts when certain important actions (commit, push, etc.) occur—are baked right into Git, so if you are comfortable with Bash and the internals of the world’s most popular version control system—you don’t need any external tools per se: just edit ./.git/hooks/pre-commit and put in some well-formed script that will, for instance, lint your files before you commit them.
However, when you’re working on a project, you’re most interested in writing that project’s code—not the code that checks it. In the world of modern web development, tooling is everything, and a myriad of tools exist for a single reason: reducing overhead and complexity. Git hooks are no exception: in the JavaScript community, the weapon of choice is Husky with Webpack, Babel, and create-react-app relying on this Node-based tool; in the Rails-centric, backend world, however, things are mostly ruled by Overcommit which comes as a Ruby gem.
Both tools are excellent in their own right, but in a mixed team of frontend and backend developers—like Evil Martians—you’ll often end up having two separate setups for Ruby and JavaScript with the frontenders and backenders linting their commits in their preferred way.
With Lefthook, you don’t need to think twice—it’s a single Go binary that has wrappers both for JavaScript and for Ruby. It can also be used as a standalone tool for any other environment.
For most common use cases, Lefthook requires zero setup.
The Go language makes Lefthook lightning-fast and provides support for concurrently executed scripts out of the box. The fact that the executable is a single machine code binary also removes the need to mind external dependencies (Husky + lint-staged add roughly fifteen hundred dependencies to your node_modules). It also removes the headache of reinstalling dependencies each time your development environment is updated (try running a globally installed Ruby gem with another version of Ruby).
With Lefthook mentioned either in package.json or Gemfile, and a lefthook.yml configured in the project’s root (see examples below), the tool will be installed and used against your code automatically on the next git pull, yarn install/ bundle install and git add/git commit—with zero overhead for new contributors.
