Question: use of cron

[bkraul]

Hopefully this is a simple question. How does one properly implement cron jobs using the webdevops images? I am specifically using the webdevops/php-apache:alpine image.

I know the ENV var (SERVICE_CRON_OPTS) allows for cron options but I do not see how to properly set up the jobs in the documentation.

I am currently mounting the /etc/cron.d folder to a persisted volume, but I suspect this is not the best way to go about it...

Thank you for your help!

[htuscher]

The SERVICE_CRON_OPTS are actually just the arguments passed to the crond when it's starting (https://linux.die.net/man/8/crond).

The current solution is to either mount the cron.d folder or build a custom image with the crontab file copied into the image.

[bkraul]

Works for me! Thank you.

[bkraul]

Ok so maybe not so fast 😢 . I mounted the /etc/cron.d folder to my host's persisted storage and placed a file there called myfile with the following content:

* * * * * application echo "Cron is running" > /etc/cron.d/log.txt 2>&1 

The file is marked as chmod +x and is owner by root:root (Note the empty line at end, as I have read it matters).

supervisorctl says the crond service is running. This is on webdevops/php-apache:alpine.

However, the job does not seem to be running (no log.txt file being created/updated and no docker stdout either). What am I missing?

[bkraul]

I see a /opt/docker/bin/service.d/cron.d//10-init.sh that runs on starting the container. It looks for files on /opt/docker/etc/cron, and it copies them to /etc/cron.d after making some changes to them (adding an empty line at end and setting permissions to 644). I am a little confused as to what's going on.

[bkraul]

OK so, interestingly enough. I changed my image to webdevops/php-apache (which I assume is the debian/ubuntu variant), and my cron job runs like so:

I am mounting /opt/docker/etc/cron to my persisted storage, I am putting my file there, now as 20-myjob with the same content. The file ends up being copied to /etc/cron.d per my previous post.

I can see the job running on stdout.

Which begs the question, why does the job not run on the alpine tag?

[bkraul]

UPDATE: Went back to mounting /etc/cron.d after seeing that 10-init.sh keeps adding a blank line to the files every time the container starts. Job still runs fine on debian/ubuntu variant, but not on alpine.

[bkraul]

Any update on why cron.d jobs don't seem to be working on the alpine variant?

[htuscher]

Sorry, won't have time before christmas to look into it

[bkraul]

No worries. Have a merry Christmas!

[bkraul]

Hey man, just touching base with you on this. It would be awesome if cron would work as expected on the alpine tag, as the image is much leaner.

[bemeyert]

Same problem here. Jobs created via crontab -e work just fine. But stuff in /etc/cron.d/ is not running.

[bemeyert]

BTW: Starting the image with SERVICE_CRON_OPTS="-c /etc/cron.d/" doesn't help either.

[bemeyert]

Any news on this? Currently I work around this issue with:

crontab -l | cat - <( cat "$CRON_FILE" ) | crontab -