require 'dotenv/tasks' namespace :heroku do desc 'Generate the Heroku gems manifest from gem dependencies' task gems: :dotenv do RAILS_ENV = 'production'.freeze 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