Using mod_auth_mellon behind reverse proxy

Issue

• We’d like to use mod_auth_mellon behind a reverse proxy, but mod_auth_mellon doesn’t respond(redirect) with a valid frontend URL. mod_auth_mellon exposes its own internal URL.

For example, if we run mod_auth_mellon (http://internal.example.com:8888) behind AWS ALB (https://frontend-url.example.com), AWS ALB passes their frontend URL via X-Forwarded-* HTTP header, but mod_auth_mellon doesn’t respect it, and redirects based on his URL (http://internal.example.com:8888).