This is a Heroku buildpack of XVFB and xvfb-run(http://www.x.org/archive/current/doc/man/man1/Xvfb.1.xhtml).
Example usage:
$ heroku create --stack cedar --buildpack http://github.com/douglasjsellers/heroku-xvfb-buildpack
# or if your app is already created:
$ heroku config:add BUILDPACK_URL=http://github.com/douglasjsellers/heroku-xvfb-buildpack
$ git push heroku master
If you're using heroku-buildpack-multi to include other buildpacks, you should set environment variable by your own to include following paths.
PATH="/usr/local/bin:/usr/bin:/bin:/app/vendor/xvfb/bin"
LD_LIBRARY_PATH="/usr/local/lib:/usr/lib:/lib:/app/vendor/xvfb/lib"