CdnTags

Using a CDN in development is kind of painful when the network is unstable, however in production common libraries should generally be served via a CDN. This gem helps to automatize this process.

This gem has been tested with Rails 3 and 4, and Ruby 1.9, 2.0 and 2.1.

Installation

Add

gem 'cdn_tags'

to your Gemfile and run

bundle install

Configuration

Create config/initializers/cdn_tags.rb and configure your assets. You can generate it by using

rails generate cdn_tags:install

Here is a sample configuration.

CdnTags.configure do |c|
  c.scripts_urls = {
    '/path/to/jquery' => '//code.jquery.com/jquery-2.1.1.min.js',
  }
  c.stylesheets_urls = {
    '/path/to/bootstrap' => '//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css'
  }
end

This will automatically add the files to Rails.application.config.assets.precompile. If you want to disable this behavior, you can set add_to_precompile to false in the configuration.

Configuration items

• scripts_urls (Hash, default: {}): The scripts that should be served from a CDN.
• stylesheets_urls (Hash, default: {}): The stylesheets that should be served from a CDN.
• add_to_precompile (true|false, default: true): Automatically add scripts to Rails.application.config.assets or not.
• raise_on_missing (true|false, default: false): Raise an exception or not if the asset used with CDN helper is not defined in scripts_urls or stylesheets_urls.
• cdn_environments (Array, default: [:production]): The environments in which CDN should be used instead of normal asset.

Usage

Just replace javascript_include_tag and stylesheet_link_tag by javascript_cdn_include_tag and stylesheet_cdn_link_tag.

For example,

<%= javascript_include_tag '/path/to/jquery' %>
<%= stylesheet_link_tag '/path/to/bootstrap' %>

becomes

<%= javascript_cdn_include_tag '/path/to/jquery' %>
<%= stylesheet_cdn_link_tag '/path/to/bootstrap' %>

This will result in the following HTML output.

• In development and test environments:

<script src="/assets/jquery-1.9.1.js?body=1"></script>

• In production environment:

<script src="http://code.jquery.com/jquery-1.9.1.js"></script>