ActionDispatch::GzStatic is a derivative of ActionDispatch::Static, that has been modified to serve the .gz files that are created by the Rails asset precompiler.

If you are using Rails to serve static assets in production, and you are using the asset precompiler, then it is probably a good idea to use this gem. If you running on Heroku's Cedar stack, this includes you.

ActionDispatch::GzStatic is a better solution that using Rack::Deflater on your static assets, because this has the undesirable side effect of recompressing assets that are already compressed, such as images.

Add this line to your application's Gemfile:

gem 'action_dispatch-gz_static'

Add this to application.rb:

# The railtie initializer will look for ActionDispatch::Static, and swap it
# with ActionDispatch::GzStatic
config.serve_static_assets = true

# This isn't required, but is generally a good idea.
config.static_cache_control = "public, max-age=#{1.month.to_i}"