@ A Former User
I just wanted to note that the regex isn't necessary. I just installed and my working config is as follows:
location /forum/ {
proxy_pass http://172.17.2.3:4567;
proxy_redirect off;
proxy_set_header Host $http_host;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-NginX-Proxy true;
# Socket.IO Support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
}