A Heroku app deploy rake file that automates asset syncing to S3 via the asset_sync gem by doing the asset compilation locally with the correct ENV vars for asset_sync.

deploy.rake

module RailsApplication
  module Deploy
    class << self
      def run(*cmd)
        system(*cmd)
        raise "Command #{cmd.inspect} failed!" unless $?.success?
      end

      def deploy(app, branch = "master")
        branch ||= "master" #in case it was passed as nil

        puts "-----> Compiling Assets..."
        heroku_env_vars = heroku_app_env_vars(app)
        heroku_env_vars.each {|k, v| ENV[k] = v unless ENV[k].present?}
        run "git checkout #{branch}"
        Rake::Task["assets:precompile"].execute
        run "git add public/assets"
        run "git commit -m'deploy compiled assets'"
        run "git push origin #{branch}"

        puts "-----> Pushing..."
        #run "git push git@github.com:RailsApplication/#{app}.git HEAD:master -f"
        run "git push --force git@heroku.com:#{app}.git #{branch}:master"

        puts "-----> Migrating..."
        run "heroku run rake db:migrate --app #{app}"

        puts "-----> Seeding..."
        run "heroku run rake db:seed --app #{app}"

        puts "-----> Restarting..."
        run "heroku restart --app #{app}"
      end

      def heroku_app_env_vars(app)
        heroku_env_vars_output = `heroku config -a #{app}`
        heroku_env_vars_output_split = heroku_env_vars_output.split("\n")
        heroku_env_var_lines = heroku_env_vars_output_split[1, heroku_env_vars_output_split.size]
        heroku_env_vars = heroku_env_var_lines.inject({}) do |output, line|
          match_data = line.match('([^:]+):(.*)')
          output.merge match_data[1].strip => match_data[2].strip
        end
      end
    end
  end
end

desc "Deploy heroku app from branch (or master by default)"
task :deploy, [:app, :branch] => [:environment] do |t, args|
  RailsApplication::Deploy.deploy(args[:app], args[:branch])
end