A minimal example on how to run a docker container app with GUI on an Xvfb.
git clone git@github.com:goncalo-godwitlabs/xvfbdc.git
cd xvfbdc/
make build
make run
A frame was dumped into mount/shot.xwd. In order to view it run:
xwud -in ./mount/shot.xwd
or convert it to JPEG and open with a common image viewer:
convert mount/shot.xwd shot.jpg
xdg-open shot.jpg