Installing custom modules into docker container

问题:

I have several services running in their own Docker containers. In my project I also have a lib folder containing some small modules that all the services need.

What is the best way to include these modules into the Docker containers? Obviously third party modules I just use RUN pip install -r requirements.txt, is there a similar way I can include my own modules?

回答1:

I would suggest using data containers. You can achieve a similar approach the rails guys are doing when caching bundler gems between image builds and multiple containers:

In your docker-compose.yml (I assume you are using docker compose) file you can add a data container that can be mounted into your other containers:

version: '2'
services:
  web:
    build: .
    volumes:
      - .:/app
      - bundle:/bundle

volumes:
  bundle: {}

By default, the container is created when it does not exist.

I'm not familiar with pip, but I think it could work in a similar way as with bundler: You set the pip installation path to your data container and get a persisted layer where pip will put all it's modules. When another container needs the same modules, just mount the data container.

Maybe you have to work out some issues, but I think the main idea could work in your case.

回答2:

I ended up managing it out by mounting the lib folder into the container using docker-compose, like so:

version: '2'
services:
  frontend_web:
    build: .
    volumes:
      - ../../lib:/app/lib

I then just had to add /app/lib to the container's PYTHONPATH and I could import any module from that folder.