没有Web服务器的Python脚本运行到Docker？

Question

I have been working with Docker previously using services to run a website made with Django.

Now I would like to know how I should create a Docker to just run Python scripts without a web server and any service related with websited.

An example of normal docker which I am used to work is:

version: '2'
services:
  nginx:
    image: nginx:latest
    container_name: nz01
    ports:
      - "8001:8000"
    volumes:
      - ./src:/src
      - ./config/nginx:/etc/nginx/conf.d
    depends_on:
      - web
  web:
    build: .
    container_name: dz01
    depends_on:
      - db
    volumes:
      - ./src:/src
    expose:
      - "8000"
  db:
    image: postgres:latest
    container_name: pz01
    ports:
        - "5433:5432"
    volumes:
      - postgres_database:/var/lib/postgresql/data:Z
volumes:
    postgres_database:
        external: true

How should be the docker-compose.yml file?

Answer 1

Simply remove everything from your Dockerfile that has nothing to do with your script and start with something simple, like

FROM python:3

ADD my_script.py /

CMD [ "python", "./my_script.py" ]

You do not need Docker compose for containerizing a single python script.

The example is taken from this simple tutorial about containerizing Python applications: https://runnable.com/docker/python/dockerize-your-python-application

You can easily overwrite the command specified in the Dockerfile (via CMD ) when starting a container from the image. Just append the desired command to your docker run command, eg:

docker run IMAGE /path/to/script.py

Answer 2

You can easily run Python interactively without even having to build a container:

docker run -it python

If you want to have access to some code you have written within the container, simply change that to:

docker run -it -v /path/to/code:/app: python

Making a Dockerfile is unnecessary for this simple application.

Answer 3

Most Linux distributions come with Python preinstalled. Using Docker here adds significant complexity and I'd pretty strongly advise against Docker just to run a simple script. You can use a virtual environment to isolate a particular Python package's dependencies from the rest of the system.

(There is a pretty consistent stream of SO questions around getting filesystem permissions and user IDs right for scripts that principally want to interact with the host system. Also remember that running docker anything implies root-equivalent permissions. If you don't want Docker's filesystem and user namespace isolation, IMHO it's easier to just not use Docker where it doesn't make sense.)