title: Rails 4: get an image full url generated by Sprockets in production environment (inside rake task)
body: <p>Trying to get the image full URL inside a view rendered by a mailer.</p>
  
  <p>Is there a proper way in Rails 3+ to get the full url generated by Sprockets?</p>
  
  <p>I know of the request object hack, but since the mailer is invoked <strong>inside a rake task</strong>,
  the request data is not available, obviously.</p>
  
  <p>I'm running Rails 4 beta1 (edge)</p>