This is a first try at creating a docker-based build environment for GIMP.
The file has grown alongside building babl, GEGL, libmypaint and GIMP on a RHEL host running Docker. The main purpose of this image will be to serve as a base for building packages like Flatpak, AppImage and others, and serving them from download.gimp.org
it is not optimized at all, pulls in some extra packages, misses some optional dependencies, builds as root, ...