= Docker Python build file =
 * Run python script in docker envelope {{{
$ docker run -it --rm --name my-running-script -v "$PWD":/usr/src/myapp -w /usr/src/myapp python:3 python script.py
}}}

 * Run python3 script in docker and chown files back to original user {{{
$ docker run --rm --name az_script-20helper-split-pem.py \
        -v "$path_dir":/app -w /app \
        -v /tmp:/tmp \
        --env certName=$certName \
        --env USER_ID=$(id -u ${USER}) \
        --env GROUP_ID=$(id -g ${USER}) \
        python:3.7-alpine \
            sh -c 'python -m pip install pem ; python az_script-20helper-split-pem.py /tmp/$certName-in.pem /tmp/$certName-split ; chown --changes --silent ${USER_ID}:${GROUP_ID} /tmp/$certName-split* '

}}}

 * Python docker build file
   1. create dir myapp, in it add src/myapp.py and requirements.txt
{{{
FROM python:3.7-alpine as base
FROM base as builder
RUN mkdir /install
WORKDIR /install
COPY requirements.txt /requirements.txt
RUN pip install --install-option="--prefix=/install" -r /requirements.txt
FROM base
COPY --from=builder /install /usr/local
COPY src /app
WORKDIR /app
CMD ["python" . "myapp.py"]
}}}
 * Build with $ docker build -t myapp .
 * Run with $ docker run --rm myapp