This article assumes that you installed Discourse via the Official Simple 30 Minute Basic Install on GitHub https://github.com/discourse/discourse/blob/master/docs/INSTALL.md If you want to run other websites on the same machine as Discourse, you need to set up an extra NGINX or HAProxy proxy in front of the Docker container. This guide assumes you already have Discourse working - if you don’t, it may be hard to tell whether or not the configuration is working.
This is a companion discussion topic for the original entry at https://henrywithu.com/run-multi-sites-on-the-same-server-as-discourse/