So, while this is not exactly a typical "self-hosting" question as many users might not be using domains, I would be curious if anyone else has any experience with this.
I have NGinx Proxy Manager installed on a vps and a few docker instances that host various services (wordpress, a gitlab, etc etc) that I have bound to specific ports (wordpress to port 80, gitlab to port 3000, to give made up arbitrary examples.)
I also have a domain and a few subdomains registered as Type A resource records that look like:
[www.]somedomain[.com]
[gitlab.]somedomain[.com]
The essence of the question: When I go to NGinx Proxy Manager and register a "Proxy Host" for the gitlab subdomain, like:
Domain: gitlab.somedomain.com
Scheme: http
Forward Hostname: <IP ADDRESS HERE>
Forward Port: 3000 (AKA the port gitlab is hosted on)
This works, but it comes with the drawback that the port number is then exposed in the url bar like so:
gitlab.somedomain.com:3000
So is there some way to fix this on the NGINX proxy manager side of things? Or is this a case where I'm doing this completely wrong and someone with web-dev experience can help me see the light. While it's not a huge hindrance to my use-case, it would still be nice to understand how this is supposed to work so that I can host more services myself that require domain names without having to shell out for isolated IPs. So if I hosted a lemmy or kbin, for example, I could actually configure it to use my subdomains correctly.
As an update, I think this was a side effect of how Wordpress / Gitlab was set up, where it was expecting it to be IP:PORT, which would force a redirect to the port specifically. Using the subdomain as the setting for web url seemed to resolve my problem. Thanks for the replies from everyone as all of the advice here is still really useful!