I have this Dockerfile (where I am using miniconda just because I would like to schedule some python scripts, but it's a debian:jessie docker image):
FROM continuumio/miniconda:4.2.12
RUN mkdir -p /workspace
WORKDIR /workspace
ADD volume .
RUN apt-get update
RUN apt-get install -y cron
ENTRYPOINT ["/bin/sh", "/workspace/conf/entrypoint.sh"]
The script entrypoint.sh that keeps the container alive is this one:
#!/usr/bin/env bash
echo ">>> Configuring cron"
service cron start
touch /var/log/cron.log
mv /workspace/conf/root /var/spool/cron/crontabs/root
chmod +x /var/spool/cron/crontabs/root
crontab /var/spool/cron/crontabs/root
echo ">>> Done!"
tail -f /var/log/cron.log
From the docker documentation about supervisor (https://docs.docker.com/engine/admin/using_supervisord/) it looks like that could be an option as well as the bash script option (as in my example), that's why I decided to go for the bash script and to ignore supervisor.
And the content of the cron details /workspace/conf/root is this:
* * * * * root echo "Hello world: $(date +%H:%M:%S)" >> /var/log/cron.log 2>&1
(with at the bottom as an empty line \n)
I can not find a way to see that Hello world: $(date +%H:%M:%S) each minute appended to /var/log/cron.log, but to me all the cron/crontab settings are correct.
When I check the logs of the container I can see:
>>> Configuring cron
[ ok ] Starting periodic command scheduler: cron.
>>> Done!
Also, when logging into the running container I can see the cron daemon running:
root@2330ced4daa9:/workspace# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 4336 1580 ? Ss+ 13:06 0:00 /bin/sh /workspace/conf/entrypoint.sh
root 14 0.0 0.0 27592 2096 ? Ss 13:06 0:00 /usr/sbin/cron
root 36 0.0 0.0 5956 740 ? S+ 13:06 0:00 tail -f /var/log/cron.log
root 108 0.5 0.1 21948 3692 ? Ss 13:14 0:00 bash
root 114 0.0 0.1 19188 2416 ? R+ 13:14 0:00 ps aux
What am I doing wrong?
