初学者Docker docker-compose

Question

I'm going through this tutorial and I've successfully got the stack up and running.

What's bugging me is that when I change my code (in the web service) on my host, it does automatically make the changes when I reload the page in the browser. I don't understand why it's doing that. Here's my docker-compose.yml file:

web:
  restart: always
  build: ./web
  expose:
    - "8000"
  links:
    - postgres:postgres
    - redis:redis
  volumes:
    - ./web:/usr/src/app
    - ./web/static:/usr/src/app/static
  env_file: .env
  environment:
    DEBUG: 'true'
  command: /usr/local/bin/gunicorn docker_django.wsgi:application -w 2 -b :8000

nginx:
  restart: always
  build: ./nginx/
  ports:
    - "80:80"
  volumes:
    - /www/static
  volumes_from:
    - web
  links:
    - web:web

postgres:
  restart: always
  image: postgres:latest
  ports:
    - "5432:5432"
  volumes:
    - pgdata:/var/lib/postgresql/data/

redis:
  restart: always
  image: redis:latest
  ports:
    - "6379:6379"
  volumes:
    - redisdata:/data

---

I didn't think that this was gunicorn doing the reloading because I believe gunicorn needs the --reload flag to actually do hot reloading.

Answer 1

This line means that you are mapping locations on your host to locations within your web container.

  volumes:
    - ./web:/usr/src/app
    - ./web/static:/usr/src/app/static

Therefore any time you change you change code in the .web directory, it is updated within the container. If you don't want that to happen then you need to copy those directories when you build your container by specifying that in Dockerfile for that container.