Question

Compass uses chunky_png to render the sprites. It adds a hash to the end of the file to force caches to download the new image sprites. Is there a way to turn this cache busting off?

Answer 1

Unfortunately asset_cache_buster :none option does not disable adding the hash to the end of the filename.

Like I wrote few time ago (in french), Compass has no way to disable the cache hash buster, but I propose a solution.
In your configuration file (eg config.rb) add the following lines:

# Make a copy of sprites with a name that has no uniqueness of the hash.
on_sprite_saved do |filename|
  if File.exists?(filename)
    FileUtils.cp filename, filename.gsub(%r{-s[a-z0-9]{10}\.png$}, '.png')
  end
end

# Replace in stylesheets generated references to sprites
# by their counterparts without the hash uniqueness.
on_stylesheet_saved do |filename|
  if File.exists?(filename)
    css = File.read filename
    File.open(filename, 'w+') do |f|
      f << css.gsub(%r{-s[a-z0-9]{10}\.png}, '.png')
    end
  end
end

Now, uses compass cleanto remove generated files and restarts a compilation with compass compile.
You obtain, for example, a images/icons-scb1e5456d5.png file and a images/icons.png file. In the stylesheets, all references to the sprites now point to the version without hash.

Be sure to keep the file has a hash provided to optimize compile times by Compass.