Eugene's image was my starting point, I made modificaitons to it to incorporate s6-overlay, as well as using the latest Alpine Linux and Xpra build, in order to make it a suitable base image for easily running GUI apps on a headless server, similar to Jocelyn's image, but more useful to my purposes.
Automatically starts an Xpra server, which allows you to access an application (or applications, or a whole desktop) with a web browser or over SSH (similar to X Forwarding).
Check .env file for default Xpra and user options. Using this image as a base, create a startup script for your application and copy it to /etc/services.d/app/run to have it automatically start, and restart if closed/crashed.
Example:
# Pull base image.
FROM [image id]
# Install xterm.
RUN add-pkg xterm
# Copy the start script.
COPY start /etc/services/app/run
I hacked this image together, I'm by no means an expert. It works for my purposes, but you very well may encounter issues.