Docker: Help needed: how to add a cron task?

[MaxenceG2M]

Hi here!

I want to add a cron task but I don't understand how to do...
For information, I want to use the Preview Generator application. (I have a lot of issues with Gallery, but it's another subject.)

Someone can help me?
Thanks !

[pierreozoux]

Check the example folder

[MaxenceG2M]

Thank @pierreozoux

Yeah I did it. Actually, I use the docker-compose example with maria-cron-redis).
So I have a cron container - the entrypoint is cron.sh:

#!/bin/sh
set -eu

exec busybox crond -f -l 0 -L /dev/stdout

This entrypoint use busybox that I don't know much. If I correctly understand, it's a way to have a tiny cron.
But I don't figure out how to add a task: there's no crontab or something...

In the example folder, there is a Dockerfile example with a supervisord.conf file who run the same cron.sh...

So, I'm a little lost and don't know how to start...

[SnowMB]

The crontab was already written when the dockerfile was build. It is already part of the image. If you want to append another cronjob, try making a derived dockerfile something like this (not tested):

FROM nextcloud:apache
RUN echo '*/10 * * * * ./occ preview:pre-generate' >> /var/spool/cron/crontabs/www-data

[J0WI]

I would recommend to add */10 * * * * docker exec -u www-data <my-nextcloud> <my-cmd> or an equivalent systemd timer on your host.

[MaxenceG2M]

Thanks @J0WI! That what I did and it's OK.
I think I don't understand correctly the cron container usage.

Thanks for your help!