Rails asset pipeline - image_path helper only working in development

Question

I have a problem with asset preocompilation in Rails (3.2.7).

I am including an favicon like this:

Answer 1

You must tell Rails which assets are to be precompiled. You do this in config/application.rb or config/environments/production.rb with the config.assets.precompile config key.

Rails starts with a default list of assets to precompile, including ["application.js", "application.css"], but if you want your own assets to be precompiled too, you have to add them to the list.

For example:

# config/application.rb
module MyApp
  class Application < Rails::Application
    # other config ...

    config.assets.precompile += ["screen.css", "*.png"]
  end
end

Answer 2

Ok, after a couple of tries I figured out, how to fix this. Nevertheless it´s a little bit strange and does not satisfy me completely. It only worked for me, when I set digest to true and provide the path to the manifest:

config.assets.compile = false
config.assets.digest = true
config.assets.manifest = Rails.root.join("public/assets")

It would be interesting to know, what´s behind this "logic".