Run Cron jobs inside Docker container

Dockerfile.cron

FROM python:3.8.12-slim-buster

RUN apt update && apt install -y cron vim
RUN mkdir /code

ARG DB_HOST
ARG DB_NAME
ARG DB_USER
ARG DB_PASS
ARG CRON_SCHEDULE
ENV DB_HOST=${DB_HOST}
ENV DB_NAME=${DB_NAME}
ENV DB_USER=${DB_USER}
ENV DB_PASS=${DB_PASS}
ENV CRON_SCHEDULE=${CRON_SCHEDULE:-"* * * * *"}

COPY ./app /code/app
COPY index.py /code/

WORKDIR /code
RUN touch .myenv
RUN echo "export DB_HOST=${DB_HOST_REMOTE}" >> .myenv
RUN echo "export DB_PASS=\"${DB_PASS_REMOTE}\"" >> .myenv
RUN echo "export DB_USER=${DB_USER_REMOTE}" >> .myenv
RUN echo "export DB_NAME=${DB_NAME_REMOTE}" >> .myenv
RUN echo "source /code/.myenv" > load.sh && chmod +x load.sh

RUN echo "python /code/index.py >> /code/cron.log 2>&1 &" > script.sh

RUN chmod +x script.sh
RUN touch cron.log && chmod 664 cron.log
RUN crontab -l | { cat; echo "PATH=/bin/:/usr/bin:/usr/local/bin:$PATH\n\n\
${CRON_SCHEDULE} BASH_ENV=/code/load.sh bash /code/script.sh\n\
"; } | crontab -

CMD /etc/init.d/cron start && echo "Listening log..." && tail -f /code/cron.log