Manual asset pipeline for Sinatra

assets.rake

namespace :assets do

...
  def get_relative_path(file_path, base_path)
      (Set.new(file_path.split(File::SEPARATOR)) - Set.new(base_path.split(File::SEPARATOR))).
          to_a.join(File::SEPARATOR)
  end
...

  desc 'compile assets'
  task :compile do

    require 'sprockets-image_compressor'
    require 'sass'
    require 'closure-compiler'
    require 'set'

    ::RideSpark::BaseWebApplication.apps.each do |app|
      sprockets = app.settings.sprockets
      sprockets.css_compressor = :sass
      sprockets.js_compressor = :closure
      Sprockets::ImageCompressor::Integration.setup sprockets

      sprockets.paths.each do |path|
        Dir.glob(File.join(path, '**/*')) do |asset_path|

          asset = get_relative_path(asset_path, path)
          app_dir = get_relative_path(asset_path, APPS_HOME).split(File::SEPARATOR).first
          asset_dir = File.file?(asset_path) ? '' : asset
          dst_path = File.join(APPS_HOME, 'assets', 'public', app_dir, asset_dir )
          dst_file = File.join(dst_path, asset)

          FileUtils.mkdir_p(dst_path) unless Dir.exist?(dst_path)
          File.write(dst_file, sprockets[asset].to_s) if asset_dir.empty?
          $logger.info "Copied #{asset} to #{dst_path}"
        end
      end
    end
  end

  desc 'clean assets'
  task :clean do
    Dir.chdir File.join(APPS_HOME, 'assets', 'public')
    Dir.entries('.').each do |e|
      if !%w(. ..).include?(e) && File.directory?(e)
        FileUtils.rm_rf(e)
        $logger.info "Recursively deleted #{e}"
      end
    end
  end

end

base_app.rb

class BaseWebApplication < BaseApplication

    use Rack::UserLocale
    I18n::Backend::Simple.send(:include, I18n::Backend::Fallbacks)
    I18n.default_locale = CONFIG['site']['lang']

    def self.apps
      ObjectSpace.each_object(Class).select {|klazz| klazz < self}
    end

    def self.inherited(subklass)
      super

      subklass.instance_eval do

        app_dirname = caller[3].split('/')[0..-2].join('/')
        translations_dir = File.join(app_dirname, 'locales')

        if File.directory?(translations_dir)
          I18n.load_path += Dir[File.join(translations_dir, '*.yml')]
          I18n.backend.load_translations
        end

        set :static_cache_control, [:public, :max_age => 604800]  # one week

        set :haml, ugly:true unless %w(development test).include?ENV['RACK_ENV']

        set :views, File.join(app_dirname, 'views')
        set :public_folder => File.join(app_dirname, 'public')

        set :sprockets, Sprockets::Environment.new(app_dirname){|env| env.logger = $logger}

        %w(assets vendor).each do |dir|
          %w(css js img ico).each do |type|
            path = File.join(dir, type)
            settings.sprockets.append_path(path) if File.directory?(File.join(app_dirname, path))
          end
        end

        get '/assets/*' do
          file = params[:splat].first

          if %w(development test).include?ENV['RACK_ENV']
            asset = settings.sprockets[file]
            asset ? [200, {'Content-Type'=>asset.content_type}, asset.to_s] : 404
          else
            send_file File.join(APPS_HOME, 'assets', 'public', File.basename(app_dirname), file)
          end
        end


      end
    end