Running pgadmin in custom path.

Let me explain my setup. I have AWS Load balancer, where I have path mapping to '/pg' which points ecs pgadmin container. 

When I try to connect mydomain.com/pg , it's reaching container, but pgadmin says, no such folder /pg exists. No such url found. 

Pgadmin looking for location /pg and failed to load site.

Also, I'm passing SERVER HOST URL as /pg as param in ecs container. It fails constructs URL. 

AWS support says Load balancer forwards path as it is to pgadmin and container should take care of it.

How can I host pgadmin in /pg ? I use public docker image, should I build custom docker file with any change?

Need your help.

Thank you 

Dhilip Kumar