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Managing Bower Web Packages with


Bower describes itself as a ‘change manager for the web’. An easy way to understand Bower is that it is a tool for fetching various libraries and their dependenceis and includng them into your project.

For example if you needed to pull in jQuery into your project then you can run:

bower install jquery

So Bower has introduced a simple and managable way to bring in libriaries and their dependancies into your JavaScript projects. It certainly beats trying installing things manualy!


Bundler is a tool that has been around longer than Bower and essentially does the same thing as Bower but for Ruby Gems. A common way developers are introuduced to Bundler is via Rails since Rails uses Bundler by default. Developers simply add their applications Gem dependenices to the applications Gemfile and run bundle install on the command line.

Combining Bower and Bundler with

Rails Assets is a great way to manage all your external assets in Rails. Note this is not a substitute for the Asset Pipeline! Rails Assets describes itself as the frictionless proxy between Bundler and Bower. It does this by automatically converting the packaged components (from Bower) into Ruby Gems that are easily droppable into the Rails asset pipeline and stay up to date.

Rails Asset Pipeline

The Asset Pipeline was introduced in Rails 3.1 and is a fantasitic addition to the stack. If we add a JavaScript file to our app/assets/javascripts directory and we already have require-tree then this file will be automaticaly sent to the browser (via a call to javascript_include_tag in the layout file). The Asset Pipeline also takes care of the Production obfuscation and minification requiremetns as well as producing single .js and .css files amongst other things.

The problem that solves

One option for adding ‘web packages’ (that is things like JavaScript libraries, CSS libraries and so on) to our Rails application was to go hunting for the libary file itself and drop that into ‘lib/assets/..’ (or other) so that it is pulled into the asset pipline. The problem here was finding ways to keep these files up to date and handle dependencies correctly.

An alternative was to go hunting for a gem that is built with the intension of wraping the web package in a Rails Engine that can be installed and therefore included automatically in the asset pipleine. The problem here is that the versioning becomes quite confusing (one version for the Gem and one for the web package) and if you want to include a later version of the framework then you would probably have to fork the Gem yourself.

The future is here with !

Enter - which allows developers to simply add the web package to their Gemfile and install via bundle install command. Very familiar, easy to setup and no hassel. Developers no longer any need to maintain separate Gems for intsalling web packages like jQuery or Bootstrap or Angular JS - just use from now on!

Getting started with

To get started using the ‘frictionless proxy’ just do the following:

Add as a new gem source. For example the top of your Gemfile might look like this:

source ''
source ''

# Gems listed here ...

Add any Bower related web packags as you would any new Gem using the syntax gem 'rails-assets-BOWER_PACKAGE_NAME'. For example the following is an example Gemfile that includes Bootstrap, AngularJS and Leaflet librarries via Bower!

source ''
source ''

gem 'rails-assets-bootstrap'
gem 'rails-assets-angular'
gem 'rails-assets-leaflet'

Now you can require the BOWER-PACKAGE-NAME in your asset pipline as follows. This is how we can include Bootstrap, Angular JS and Leaflet JavaScript files in the asset pipleine:

//= require_self
//= require bootstrap
//= require angular
//= require leaflet
//= require_tree .
//= require_tree shared

Here is an example of including CSS dependencies into your Rails Application:

  *= require_self
  *= require bootstrap
  *= require leaflet
  *= require_tree .
  *= require_tree shared

Please checkout the Rails Assets website for further details about getting started.

I hope you get a chance to try out in your Rails projects and you will never go back to the old way again!