Rake task to generate heroku .gems file from gems listed in environment.rb

heroku.rake

namespace :heroku do

  desc "Update .gems with a list of the required gems"
  task :gems => 'gems:base' do
    gem_lines = []
    gem_array = Rails.configuration.gems.reject{|g| g.frozen? && !g.framework_gem?}.map do |gem|
      line = gem.name
      line += " --source #{gem.source}" if gem.source
      line += " --version '#{gem.requirement.to_s}'" if gem.requirement
      gem_lines << line
    end

    if (RAILS_GEM_VERSION rescue false)
      gem_lines << "rails --version #{RAILS_GEM_VERSION}"
    else
      gem_lines << 'rails'
    end
    
    config_path = File.join(Dir.pwd, '.gems')
    file = File.open( config_path, 'w' )
    file.write(gem_lines.join("\n"))
    file.close
        
    puts ".gems has been updated with your application's gem dependencies."
  end

end