With heroku-buildpack-apt, this buildpack enables running
xvfb-run program
on Heroku. To use it, ensure that heroku-buildpack-apt comes earlier than this in the buildpacks list, and include
xvfb
in your Aptfile.
Some inspiration (for dealing with Xvfb's compiled-in XKB_BIN_DIRECTORY, which leads to it complaining that it can't find /usr/bin/xkbcomp) comes from fxtentacle's answer to http://stackoverflow.com/a/34219781/1162903.
This might only work on Heroku's cedar-14 platform. Issues reported on heroku-16: