Bundler for Ruby

Introduction

A really easy way to take the headache out of keeping your gems at the right version (especially when source controlling your projects) is to use a package manager. Today’s post is about Bundler which helps maintain your environment for Ruby development.

Let’s go!

Install bundler.

$ gem install bundler

You’re now installed and ready to start bundling. The first job that you need to do is to write a metafile containing all of the gems that your application requires and where bundler should fetch those gems from. This metafile is called your Gemfile. A Gemfile will take the following format.

source "http://rubygems.org"
gem "nokogiri"              
gem "premailer"             
gem "tlsmail"

The source tells bundler what site to download the gems from. The most common ones that I’ve seen are as follows.

source :rubygems
source "http://rubygems.org"
source :rubyforge
source "http://gems.rubyforge.org"
source :gemcutter
source "http://gemcutter.org"

You can see each of the sources here with a symbolic shortcut that you can use also. The gem tells bundler that you have a dependency. You can also constrain the version of your dependencies on these lines by using version information after the gem. Now that you’ve created your Gemfile, you can install all of the gems and their dependencies simple by changing directories to where your Gemfile resides and typing the following at the prompt.

$ bundle install

Now you have all of your dependencies installed for your application. Doing this will generate a Gemfile.lock file in your directory also. Make sure that you source control both your Gemfile and Gemfile.lock.

That’s it.