Docker Console App Taking Many Arguments

Possible usage:

Use cases:

• app is a console app
• app needs some input (input data could be put inside mapped in dir. E.g. /home/<username>/app_in)
• app generates some output (output data could be saved inside mapped out dir. E.g. /home/<username>/app_out)
• app needs to run a few times with different commands
• some operations needed before app starts

Entrypoint script:

#!/bin/sh
# Activate venv
source /arg/venv/bin/activate
# some commands could be put here
# they will be executed before commands given with docker run command and before test_app.py as well
for var in "$@"
do
    eval "$var"
done

Sample app Dockerfile:

# Python Debian image as a base
FROM python:3.8-slim-buster
# Package manager update and new packages installation
RUN apt-get update && apt-get upgrade -y
RUN apt-get install -y <some_packages>
# Copy application to container
COPY test_app.py /app/test_app.py
COPY requirements.txt /app/requirements.txt
# Change dir, dirs creation, venv install and packages install
WORKDIR /app
RUN mkdir /app/in /app/out
RUN pip install virtualenv
RUN virtualenv --python /usr/local/bin/python3.8 venv
RUN /bin/sh venv/bin/activate && pip install -r requirements.txt
# Env variables set if needed
ENV PYTHONPATH /app/venv/lib/python3.8/site-packages:/app
# Copying entrypoint script and change permissions and set as entrypoint
COPY entrypoint.sh /app/entrypoint.sh
RUN ["chmod", "+x", "/app/entrypoint.sh"]
ENTRYPOINT ["/app/entrypoint.sh"]

Docker image build

Dockerfile’s name is app.Dockerfile and is located in the same dir with entrypoint.sh, test_app.py and requirements.txt

docker build -t docker_repo/app_name . -f app.Dockerfile

Sample usage command

Below command will:

• start your contenerized app in interactive mode
• map in and out dirs as volumes (possible data exchange with container and host)
• run test_app.py
• copy everything to out dir
• stays in container because of /bin/bash at the end

  docker run -it -v "/home/<username>/app_in:/app/in" -v "/home/<username>/app_out:/app/out" docker_repo/app_name "python test_app.py" "cp -a . /app/out" "/bin/bash"