According to this answer (which might be outdated) it appears like running Discourse on a non-standard port is not the prettiest way:
But anyway, why not.
Thanks a lot for your answer and for bringing up Caddy, I never heard of it. Anyone interested, DO wrote a howto:
Edit : in addition, it seems like Ubuntu 16.04 users have to enable systemd-networkd service first.
sudo systemctl enable systemd-networkd
sudo systemctl start systemd-networkd
In this case @pfaffman, should I disable ssl and letsencrypt in app.yml?