Caddy dockerized, built FROM the "scratch" base
Listens on port 2015 and uses /html for its content directory. The Caddyfile is in /Caddyfile.
Here's an example to get Caddy listening on port 80:
docker run --name caddy -d -v /home/user/html:/html:ro -p 80:2015 mcoddington/caddy
Docker Pull Command