How to run a cron job inside a docker container?

Question

I am trying to run a cronjob inside a docker container that invokes a shell script.

Yesterday I have been searching all over the web and stack overflow, but I could

Answer 1

When running on some trimmed down images that restrict root access, I had to add my user to the sudoers and run as sudo cron

FROM node:8.6.0
RUN apt-get update && apt-get install -y cron sudo

COPY crontab /etc/cron.d/my-cron
RUN chmod 0644 /etc/cron.d/my-cron
RUN touch /var/log/cron.log

# Allow node user to start cron daemon with sudo
RUN echo 'node ALL=NOPASSWD: /usr/sbin/cron' >>/etc/sudoers

ENTRYPOINT sudo cron && tail -f /var/log/cron.log

Maybe that helps someone