Supervisor is a process manager. Seems pretty popular with the Docker kids.
To add your own programs, just put their .conf files in /etc/supervisor.d/.
sshd is listening on port 22. The password's in src/setup.sh and is quite
obvious.
I'd initially intended to use wsh, but I ran into #3385.
crond and rsyslog are both provided in this image. I'd not intended to run
these, but I've decided to let each container manage its own backups and other
automated tasks. As a result, /var/log needs to be minded. It's not flagged
as a volume in Dockerfile, which leaves it up to the user to map a volume with
-v if the contents are meaningful; otherwise they'll be removed when the
container is culled.