Wiring up Rack/Sprockets

config.rb

require 'sprockets'
require 'sprockets-sass'
require 'compass'

require File.join(File.dirname(__FILE__), 'static_compiler')

Encoding.default_external = "UTF-8"

Sass::Engine::DEFAULT_OPTIONS[:load_paths].tap do |paths|
  paths.push *Compass.sass_engine_options[:load_paths]
end

$sprockets_environment = Sprockets::Environment.new
$sprockets_environment.append_path 'javascripts'
$sprockets_environment.append_path 'stylesheets'
$sprockets_environment.append_path 'images'
$sprockets_environment.append_path 'spec/javascripts'
$sprockets_environment.append_path 'vendor/jasmine-1.1.0'
$sprockets_environment.append_path 'vendor/sinon-1.2.0'

config.ru

require 'rubygems'
require 'bundler/setup'

require File.join(File.dirname(__FILE__), 'lib', 'sprockets', 'rack')

run SprocketsApp

Gemfile

source :rubygems

gem 'rake'
gem 'rack'

gem 'sprockets',      '~> 2.0'
gem 'sprockets-sass', '0.3.0'
gem 'compass',        '~> 0.12.alpha'
gem 'coffee-script'
gem 'tilt',                           :git => 'git://github.com/rtomayko/tilt.git'
gem 'ejs'
gem 'eco'

rack.rb

require 'rack'

require File.join(File.dirname(__FILE__), 'config')

SprocketsApp = Rack::Builder.new do

  # This is a workaround since I can't get Sprockets to serve subdirectories properly
  map '/assets/admin' do
    run Rack::Directory.new('images/admin')
  end

  map '/assets/fonts' do
    run Rack::Directory.new('images/fonts')
  end


  map '/assets' do
    run $sprockets_environment
  end

  map '/spec' do
    run Rack::Directory.new('spec/javascripts')
  end

  map "/images" do
    run Rack::Directory.new('images')
  end

  map "/" do
    run Rack::Directory.new('www')
  end

end

static_compiler.rb

require 'sprockets'
require 'fileutils'

module Sprockets
  class StaticCompiler
    attr_accessor :env, :target, :digest

    def initialize(env, target, options = {})
      @env = env
      @target = target
      @digest = options.key?(:digest) ? options.delete(:digest) : true
    end

    def precompile(paths)
      manifest = {}
      env.each_logical_path do |logical_path|
        next unless precompile_path?(logical_path, paths)
        if asset = env.find_asset(logical_path)
          manifest[logical_path] = compile(asset)
        end
      end
      manifest
    end

    def compile(asset)
      asset_path = digest_asset(asset)
      filename = File.join(target, asset_path)
      FileUtils.mkdir_p File.dirname(filename)
      asset.write_to(filename)
      asset.write_to("#{filename}.gz") if filename.to_s =~ /\.(css|js)$/
      asset_path
    end

    def precompile_path?(logical_path, paths)
      paths.each do |path|
        if path.is_a?(Regexp)
          return true if path.match(logical_path)
        elsif path.is_a?(Proc)
          return true if path.call(logical_path)
        else
          return true if File.fnmatch(path.to_s, logical_path)
        end
      end
      false
    end

    def digest_asset(asset)
      digest ? asset.digest_path : asset.logical_path
    end
  end
end