Overcommit

overcommit is a tool to manage and configure Git hooks.

In addition to supporting a wide variety of hooks that can be used across multiple repositories, you can also define hooks specific to a repository (but unlike regular Git hooks, are stored with that repository).

Read more about Overcommit on our engineering blog.

• Requirements
  • Dependencies
• Installation
  • Automatically Install Overcommit Hooks
• Usage
• Configuration
• Built-In Hooks
• Repo-Specific Hooks
• Contributing
• Changelog
• License

Requirements

• Ruby 1.8.7+ is supported

Dependencies

Some of the hooks have third-party dependencies. For example, to lint your SCSS files, you're going to need our scss-lint gem.

Depending on the hooks you enable/disable for your repository, you'll need to ensure your development environment already has those dependencies installed. Most hooks will display a warning if a required executable isn't available.

Installation

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 --install

Automatically Install Overcommit Hooks

If you want to use overcommit for all repositories you create/clone going forward, add the following to automatically run in your shell environment:

export GIT_TEMPLATE_DIR=`overcommit --template-dir`

The GIT_TEMPLATE_DIR provides a directory for Git to use as a template for automatically populating the .git directory. If you have your own template directory, you might just want to copy the contents of overcommit --template-dir to that directory.

Usage

Once you've installed the hooks via overcommit --install, they will automatically run when the appropriate hook is triggered.

The overcommit executable supports the following command-line flags:

Command Line Flag	Description
-i/--install	Install Overcommit hooks in a repository
-u/--uninstall	Remove Overcommit hooks from a repository
-t/--template-dir	Print location of template directory
-h/--help	Show command-line flag documentation
-v/--version	Show version

Skipping Hooks

Sometimes a hook will report an error that for one reason or another you'll want to ignore. To prevent these errors from blocking your commit, you can include the name of the relevant hook in the SKIP environment variable, e.g.

SKIP=rubocop git commit

Use this feature sparingly, as there is no point to having the hook in the first place if you're just going to ignore it. If you want to ensure a hook is never skipped, set the required option to true in its configuration.

Configuration

Overcommit provides a flexible configuration system that allows you to tailor the built-in hooks to suit your workflow. All configuration specific to a repository is stored in .overcommit.yml in the top-level directory of the repository.

When writing your own configuration, it will automatically extend the default configuration, so you only need to specify your configuration with respect to the default.

Within a configuration file, the following high-level concepts exist:

• Plugin Directory: allows you to specify the directory where your own Git hook plugins are stored (if you have project-specific hooks)

• Hook type configuration (PreCommit, CommitMsg, etc.): these categories each contain a list of hooks that are available for the respective hook type. One special hook is the ALL hook, which allows you to define configuration that applies to all hooks of the given type.

• Hook configuration: Within each hook category, an individual hook can be configured with the following properties:

  • required: if true, this hook cannot be skipped
  • quiet: if true, this hook does not display anything unless it fails
  • description: text displayed when the hook is running
  • requires_files: whether this hook should run only if files have been modified
  • include: Glob patterns of files that apply to this hook (it will run only if a file matching the pattern has been modified--note that the concept of "modified" varies for different types of hooks)
  • exclude: Glob patterns of files that are ignored by this hook

  On top of the above built-in configuration options, each hook can support individual configuration. As an example, the AuthorEmail hook allows you to customize the regex used to check emails via the pattern option, which is useful if you want to enforce developers to use a company email address for their commits.

Built-In Hooks

Currently, Overcommit supports commit-msg, pre-commit, and post-checkout hooks, but it can easily be expanded to support others.

You can see the full list of hooks by checking out the hooks directory, and view their default configuration.

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 number of ad hoc Ruby checks that we run against our code to catch common errors. For example, since we use RSpec, we want to make sure all spec files contain the line require 'spec_helper'.

Inside our repository, we can add the following file to .git-hooks/pre_commit in order to automatically check our spec files:

module Overcommit::Hook::PreCommit
  class EnsureSpecHelper < Base
    errors = []

    applicable_files.each do |file|
      if File.open(file, 'r').read !~ /^require 'spec_helper'/
        errors << "#{file}: missing `require 'spec_helper'`"
      end
    end

    return :bad, errors.join("\n") if errors.any?

    :good
  end
end

The corresponding configuration for this hook would look like:

PreCommit:
  EnsureSpecHelper:
    description: 'Checking for missing inclusion of spec_helper'
    include: '**/*_spec.rb'

Contributing

We love getting feedback with or without pull requests. If you do add a new feature, please add tests so that we can avoid breaking it in the future.

Speaking of tests, we use rspec, which can be run like so:

bundle exec rspec

Changelog

If you're interested in seeing the changes and bug fixes between each version of overcommit, read the Overcommit Changelog.

License

This project is released under the MIT license.