For future searchers: you can use NGINX in front of the discourse instance, you can set the X-Real-IP to a fixed IP 127.0.0.1:
location / {
proxy_pass http://unix:/var/discourse/shared/standalone/nginx.http.sock:;
proxy_set_header Host $http_host;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-Proto https;
proxy_set_header X-Real-IP 127.0.0.1;
}
Do not leave it out because you will get errors and the app will fail to start:
Completed 500 Internal Server Error in 149ms (Views: 11.1ms | ActiveRecord: 0.0ms | Allocations: 70970)
PG::InvalidTextRepresentation (ERROR: invalid input syntax for type inet: "unix:"
LINE 7: client_ip = 'unix:',
^
)