rake deploy and rake cache_assets for Heroku (storing JS minimized and gzipped on Amazon S3)

.gitignore

# Add this
public/javascripts/all.js

application.haml

# On production, don't using caching, instead load all.js from S3

- if Rails.env.production?
  = javascript_include_tag 'http://my-bucket-name.s3.amazonaws.com/public/javascripts/all.js'
- else
  = javascript_include_tag :defaults, 'jquery.min', 'other-libs', :cache => true

cache_assets.rake

desc "cache assets"
task :cache_assets => :environment do
  BUCKET = 'my-bucket-name'
  PATHS = ['public/javascripts/all.js']

  s3_yml = "#{Rails.root}/config/s3.yml"
  s3_config = YAML.load_file(s3_yml)
  
  puts "-----> caching assets..."
  PATHS.each do |path|
    FileUtils.rm(path) if File.exist?(path)
  end

  ActionController::Base.perform_caching = true

  session = ActionDispatch::Integration::Session.new(Rails.application)
  session.get('/')
  session.follow_redirect!

  AWS::S3::Base.establish_connection!(
    :access_key_id => s3_config['production']['access_key_id'],
    :secret_access_key => s3_config['production']['secret_access_key']
  )
  
  PATHS.each do |f|
    next if File.directory?(f)

    key = f.gsub(/\.\/public/, '')
    puts " -> %s" % key

    puts "   -> uglify..."
    ugly_file = Uglifier.new.compile(File.read(f))

    puts "   -> gzip..."
    gzip_file = StringIO.open('', 'w')
    gz = Zlib::GzipWriter.new(gzip_file)
    gz.write(ugly_file)
    gz.close

    puts "   -> upload to S3..."
    AWS::S3::S3Object.store(
      key, gzip_file.string, BUCKET,
      :access => :public_read, 'Cache-Control' => 'max-age=315360000', 'Content-Encoding' => 'gzip'
    )
  end

  puts "-----> done"
end

deploy.rake

desc "cache assets, push to github, deploy to heroku"
task :deploy => :environment do
  puts "-----> running rake cache_assets"
  system("rake cache_assets") ? true : fail

  puts "-----> pushing to github"
  system("git push origin master") ? true : fail

  puts "-----> deploying to heroku"
  system("git push heroku master") ? true : fail

  puts "-----> done"
end

Gemfile

# Add this to your gemfile
group :development do
  gem 'therubyracer'
  gem 'uglifier'
  gem 'aws-s3', :require => 'aws/s3'
end

# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# Don't forget to exclude groups for HEROKU because 'therubyracer' does not work on Heroku.
#
# heroku config:add BUNDLE_WITHOUT="development:test"
# More infos about this: http://devcenter.heroku.com/articles/bundler
# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!