You'll find something like this in config/environments/production.rb
:
# Precompile additional assets (application.js, application.css, and all
# non-JS/CSS are already added)
# config.assets.precompile += %w( search.js )
You should add any assets you want to be able to link to individually, or additional manifest files, to the config.assets.precompile
array.
For example, you could make a maintenance.js
manifest file containing:
//= require foo
//= require bar
Add it to config.assets.precompile
:
config.assets.precompile += %w( maintenance.js )
And then on your maintenance page:
<%= javascript_link_tag 'maintenance' %>
See the precompiling assets section in the asset pipeline guide for more information.