I used this show notes from Jupiter Broadcasting. That’s how I was able to install it on my Ubuntu 15.10. Though I must say that if you are running Apache or ngnix and you want to install Docker with Discourse, the Docker part will always for some reason, start up first so your Apache or ngnix will most likely collide with Docker and you will have to stop Docker’s services before you can startup Apache or ngnix.
You’ll have to go into the Discourse folder and do ./launcher stop app and then sudo /etc/init.d/... start if you want to relaunch Apache or ngnix.
http://www.jupiterbroadcasting.com/93751/how-not-to-install-discourse-las-404/