Docker Compose Networks

Docker Compose allows multiple containers to join a network and be reachable by other containers on that network.

By default all containers join a network named <project_name>_default under the service’s name

Example:

services:
  web:
    build: .
    ports:
      - "8000:8000"
  db:
    image: postgres
    ports:
      - "8001:5432"

On such network the code web container cna access the database on url postgres://db:5432 (container port) and the host machine could connect using postgres://<docker_ip>:8001 (host port)