python script that generates csv within docker

Question

I have a python script that generates a csv as an output. I'm running the script in a docker container. The docker container terminates immediately when the script finishes so i can't copy the file. What would be the best way to get the csv from the container?

Answer 1

You could launch the container with a mounted volume, and then the file will be there, on your filesystem, when the container exits:

$ docker run -v $PWD/output:/usr/my/workspace mycontainer mycmd

Where mycmd outputs the CSV file to /usr/my/workspace . Your file will be in the output/ folder, on your host filesystem.

Answer 2

If you have a script in a routine interpreted language, and its key activity involves reading or writing local files, the best way to run it is not in Docker at all.

You can use ordinary Python packaging tools to declare your script's dependencies (a setup.py or requirements.txt file). While you need to do a little bit of set up to be able to run the script, it's extremely routine:

python3 -m venv venv
. venv/bin/activate
pip install -r requirements.txt
./the_script.py

Compared to a Docker-based solution, this isn't really any more complex than a typical docker run invocation; unlike Docker, most Linux and MacOS systems have Python preinstalled; and you don't need to be root or have root-equivalent permission to run the script. You also don't need to worry about the mechanics of sharing file content with the running container or the inevitable filesystem permission issues that come out of it.