Docker configuration to use existing nginx

[helghast79]

In a linux server (debian) with several running websites how can we adapt the nginx config in docker to use the already running nginx instance. In my specific case nginx is configured to proxy requests from my-site.com/miqa to localhost:8000. I can also set a subdomain like miqa.my-site.com the same way. which configs should I change in order to run miqa in this kind of environment?