Using jwilder/nginx-proxy with multiple compose files

docker-compose.advanced.yml

version: '3'

services:
  nginx-proxy:
    image: nginx:alpine
    container_name: proxy-nginx
    environment:
      - DEFAULT_HOST=hello.local
    ports:
      - 80:80
      - 443:443
    volumes:
      - conf:/etc/nginx/conf.d:ro
      - vhost:/etc/nginx/vhost.d:ro
      - html:/usr/share/nginx/html:ro
      - certs:/etc/nginx/certs:ro
      
  dockergen:
    image: jwilder/docker-gen
    container_name: proxy-dockergen
    command: -notify-sighup proxy-nginx -wait 5s:30s -watch /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro
      - ./templates:/etc/docker-gen/templates:rw # curl -o templates/nginx.tmpl https://raw.githubusercontent.com/jwilder/nginx-proxy/master/nginx.tmpl
      - conf:/etc/nginx/conf.d
      - vhost:/etc/nginx/vhost.d:ro
      - html:/usr/share/nginx/html
      - certs:/etc/nginx/certs:ro
    environment:
      - DEFAULT_HOST=hello.local

  letsencrypt:
    image: jrcs/letsencrypt-nginx-proxy-companion
    container_name: proxy-letsencrypt
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
      - ./templates:/etc/docker-gen/templates:ro
      - conf:/etc/nginx/conf.d
      - vhost:/etc/nginx/vhost.d
      - html:/usr/share/nginx/html
      - certs:/etc/nginx/certs
    environment:
      - DEFAULT_EMAIL=letencrypt@your.personal.tld
      - NGINX_PROXY_CONTAINER=proxy-nginx
      - NGINX_DOCKER_GEN_CONTAINER=proxy-dockergen

  hello:
    image: nginx:alpine
    environment:
      - VIRTUAL_HOST=hello.local
    volumes:
      - ./index.html:/usr/share/nginx/html/index.html

networks:
  default:
    external:
      name: nginx-proxy

volumes:
  conf:
  certs:
  vhost:
  html:

docker-compose.app.yml

version: '3'

services:
  thing:
    image: jwilder/whoami
    environment:
      - VIRTUAL_PORT=8000
      - VIRTUAL_HOST=whoami.local

# in order for the proxy to see this service, it needs to be on the same network
networks:
  default:
    external:
      name: nginx-proxy

docker-compose.yml

version: '3'

networks:
  default:
    external:
      name: nginx-proxy

services:
  nginx-proxy:
    image: jwilder/nginx-proxy
    environment:
      - DEFAULT_HOST=hello.local
    ports:
      - 80:80
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro

  hello:
    image: nginx:alpine
    environment:
      - VIRTUAL_HOST=hello.local
    volumes:
      - ./index.html:/usr/share/nginx/html/index.html

shell.txt

$ curl -H "Host: whoami.local" localhost