Inside Docker container - crond running but no cronjobs executed

english
#1

I have built a container from a Dockerfile, based on an Archlinux base image. Using a "RUN" command I have installed "cronie", since Arch does not come with any form of cron. Now, after the container is built, I run it and attach to it. I start manually the cron daemon, verify that it is indeed running with "ps -aux" and make the required cronjobs with "crontab -e". The thing is, no cronjobs are run...

Any ideas?

#2

You can use the package fcron, and run the cron process in foreground mode:

fcron -f
#3

To troubleshoot Cron it may be handy to run syslog in Docker container.
As described here Cron may refuse to interpret its hard-linked configuration files which is a typical situation on Docker's layered overlay(fs) file system. If Cron logs something like NUMBER OF HARD LINKS > 1 (/etc/crontab) to syslog it may help to use the following command in container's entry script:

touch /etc/crontab /etc/cron.*/*
#4

@AbhishekAnandAmralkar There is no “cron.log” file in Arch Linux. I tried “journalctl -u cronie” but it returns “No journal files were found”. Still, the daemon is running, and the jobs configures inside crontab.

#5

I mention that this is taking place inside a Docker container. No systemd is running.

#6

check cron.log file and paste error here?

#7

Will try to do later today.