Create a Pull Zone or a Push Zone before you start with the RoR CDN integration.

To set your asset host in Rails, you need to change config.action_controller.asset_host in config/production.rb:

config.action_controller.asset_host = 'example-hexid.kxcdn.com'

there is no need to specify the scheme (http:// or https://) in the config file. It's also possible to work with CNAMEs (e.g. cdn.yourdomain.com). In that case a Zone Alias needs to be created as well.

You can also set this value through an environment variable in order to make running a staging copy of your site easier.

config.action_controller.asset_host = ENV['CDN_HOST']

For this to work, CDN_HOST needs to be set on your server (pointing to your Zone e.g. example-hexid.kxcdn.com).

Once you have configured your server. Content can be delivered from KeyCDN like this:

<%= asset_path('file.png') %>

Instead of returning a path such as /assets/file.png. The URL generated will have the full path to your KeyCDN Zone such as http://example-hexid.kxcdn.com/assets/smile.png.