namespace :heroku do desc "Generate the Heroku gems manifest from gem dependencies" task :gems do RAILS_ENV='production' Rake::Task[:environment].invoke list = Rails.configuration.gems.collect do |g| command, *options = g.send(:install_command) options.join(" ") + "\n" end File.open(File.join(RAILS_ROOT, '.gems'), 'w') do |f| f.write(list) end end end