Using NGINX to reverse proxy hundreds of ports

[Reinis Rozitis]

> I get that the NGINX listen statement works on an individual port basis, so the equivalent of what's below in NGINX would at the very least require 300 listen statements.

You can listen on a port range (see below).



> FYI I've tried referencing my own declared variables from within the upstream as well as referencing $server_port but of course these don't appear to be in scope.

Depends if you want nginx to perform any active healthchecks and what kind of backends those are.

If it is http and you just need to redirect traffic instead of defining upstreams a configuration with (way) less lines could be:

    server {
        listen 10.1.0.1:2000-2299;
        location / { proxy_pass http://127.0.0.1:$server_port; }
    }


A fallback to another proxy could be configured via error_page (502). 
Something like:

error_page 502 @fallback;
location @fallback { proxy_pass http://10.1.0.2:$server_port; }

But I don't think there is a way (at least in the base vanilla) nginx to configure upstreams in a dynamic way with port ranges as in upstream {} doesn't support variables for the server definitions.

rr