communication between multiple docker compose projects

src:

• https://stackoverflow.com/questions/38088279/communication-between-multiple-docker-compose-projects
• https://docs.docker.com/compose/networking/#use-a-pre-existing-network

version: "3"
services:
  proxy:
    image: hello-world
    ports:
      - "80:80"
    networks:
      - proxynet
 
networks:
  default:
    name: custom_network

version: "3"
services:
  web:
    image: hello-world
    
networks:
  default:
    external:
      name: custom_network