docker-compose.yml

#version of docker compose
version: "3"

services:
  app:
    build:
      context: .
    ports:
      - "8000:8000"
    #change anything will be updated here in docker image
    volumes:
      - ./app:/app
    command: >
      sh -c "python manage.py wait_for_db &&
             python manage.py migrate &&
             python manage.py runserver 0.0.0.0:8000"
    #server us 0.0.0.0 which is avaible on all IP addresses that run on the
    # docker
    environment:
      - DB_HOST=db # is the name of the service that runs the databse
      - DB_NAME=app # should be the postgre DB which is the app from below
      - DB_USER=postgres # this is the user name
      - DB_PASS=supersecretpassowrd
    # here we add the depends, which can be set in different way
    # here we want the app to depend of the database service
    depends_on:
      - db
    # here we want the databse service to start before the app
    #service and the database service will be available via the network when we
    # use the hostname DB

  db:
    image: postgres:10-alpine
    # environment variables
    environment:
      - POSTGRES_DB=app
      - POSTGRES_PASSWORD=supersecretpassowrd # this password will be overriden
      # by encrypted environment variable by the deployment tool like jenkins
      # or travis, also this should never include any real password because
      # ifsees the code can access it
      # this password will be used for run the server locally