Overcommit

A gem to install and manage a configurable (but opinionated) set of Git hooks. Originally written for use at Causes.

In addition to supporting global hooks, it also allows teams to define plugins specific to a repository (installed in the .githooks directory).

Installation

The overcommit is installed as a binary via rubygems:

gem install overcommit

You can then run the overcommit command to install hooks into repositories:

mkdir important-project
cd important-project
git init
overcommit .

overcommit also accepts a handful of arguments, which can be enumerated by running overcommit --help.

Repo-specific hooks

Out of the box, overcommit comes with a set of hooks that enforce a variety of styles and lints. However, some hooks only make sense in the context of a given repository.

At Causes, for example, we have a repository for managing our Chef cookbooks. Inside this repository, we have a few additional lints we run before commits are pushed:

>> tree .githooks
.githooks
└── pre_commit
    ├── berksfile_source.rb
    ├── cookbook_version.rb
    └── food_critic.rb

food_critic.rb contains a subclass of HookSpecificCheck that runs Foodcritic against the cookbooks about to be committed (if any).

The meat of it looks like this:

module Overcommit::GitHook
  class FoodCritic < HookSpecificCheck
    include HookRegistroy
    COOKBOOKS = 'cookbooks'
    @@options = { :tags => %w[~readme ~fc001] }

    def run_check
      begin
        require 'foodcritic'
      rescue LoadError
        return :stop, 'run `bundle install` to install the foodcritic gem'
      end

      changed_cookbooks = modified_files.map do |file|
        file.split('/')[0..1].join('/') if file.start_with? COOKBOOKS
      end.compact.uniq

      linter = ::FoodCritic::Linter.new
      review = linter.check(changed_cookbooks, @@options)
      return (review.warnings.any? ? :bad : :good), review
    end
  end
end