A primer on Bundler basics

Ruby’s Bundler performs all sorts of magic for your apps’ dependencies. All sorts of magic I don’t fully understand but after reviewing some open source projects this week I gained some new insight on some of the knobs that Bundler makes available to you. Below is a summary of some of the more commmon Gemfile configs and associated Bundler commands you’ll see in the wild.

Here’s an example Gemfile we’ll use to illustrate our points:

source "https://rubygems.org"

ruby "1.9.3"

gem 'pry', require: false
gem 'pony'
gem 'airbrake'

group :test do
  gem 'minitest', require: false
  gem 'rack-test', require: false

#####A couple things to note:

  1. pry is set to require: false
  2. there are gems in the test group (also require: false)

#####Your command options:

  1. Run just bundle –> You’ll install all the gems in your Gemfile regardless of environment or require declarations. Using our example, running bundle will install all 5 gems onto our machine.

  2. Run bundle --without test –> You’ll make available to your application all the gems in the Gemfile not in the test group. In our case, you’ll end up with three active gems.

  3. Including the following in your app

  require 'bundler'

will make available to your app only those gems without a false flag. In our case, we’ll end up with two gems (pony and airbrake).

Using a mixture of these commands you can minimize the installation of unncessary external dependencies and make your app smaller. Happy bundling!