无法在docker-compose文件中为argparse传递参数

Question

I'm new to docker environment, I have a sample script which i accept cmd line args through argparse and print it. Python code below:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('-ol', '--old_file', type=str, help='path of a old file')

args = parser.parse_args()

print("Hello : " + str(args.old_file))

here is my dockerfile:

FROM python:3

COPY arguments_sample.py /arguments_sample.py

ARG ol

RUN echo $ol

ENTRYPOINT ["python", "arguments_sample.py"]

and finally my docker-compose.yml:

 version: '3'

services:
    python-service:
        build: ./docker_stage
        environment:
        - OL='Hello'
        volumes:
        - ./sample_api:/usr/src/app_sample

usually i can run the python script as below:

python arguments_sample.py -ol Henry

and it would print it as Hello : Henry

when i use docker-compose up it was printing Hello : None

It may be wrong syntax which i'm not able to figure it out. Kindly help me!

Answer 1

I don't know much about Python but I can see that you have a couple things wrong in the yml.

1. I don't think you need the - in front of the env var like you have there.
2. You don't have the proper indentation for your env var. It looks like it's the same indentation as "environment". Bump it in.
3. Those may be irrelevant because I don't think ARG and environment variables are synonymous. So the OL declaration you're making in the yml doesn't apply to the ARG declaration in the Dockerfile or your usage of it in the Python. So your problem might lie there but again I don't know much about Python, just Docker.