Something like this:

  location ~ ^/([a-z0-9_-]+)/  {
    proxy_pass http://internal-$1:8000;
  }

We pickup the service name from the URL and use it to select where to proxy_pass to. So /service1 would route to the docker container named internal-service1 . We can reach it via the name only as long as Nginx is also running in Docker and on the same network.