setup for prawn, prawnto on heroku

I'm trying to use prawn, prawnto for generating pdfs in a rails开发者_StackOverflow application hosted on heroku.

But I'm struggling on the setup.

Is it possible to use prawn, prawnto on heroku?

Is there a guide explaining what I should do?

Now I've found a solution.

first of all I created a .gems file in the root directory with

prawn
prawn-layout

so heroku installs the gems by itself.

prawnto is a plugin and could be installed with

script/plugin install git://github.com/thorny-sun/prawnto.git

in the vendor/plugin directory.

Now, its working fine. My fault was, that I thought the .gems file is just for choosing from the preinstalled gems.