Docker setup & cron

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#1

Hello

I’m running my nextclud instance via docker (compose file adopted from here). There is already a container running /cron.sh, which starts a busybox with cron, which starts cron.php every 5 minutes.

Now my question is: how to do i add additional tasks? (i.e. ./occ fulltextsearch:index)

I do not want to rebuild the nextcloud image just for adding a cron task. And i do not want to use the host for managing tasks in the container (host systemd oder host cron)

any way to manage this?

Greetings
Dakky

#2

What’s your host system?

#3

the host is running ubutu LTS

#4

Maybe you should. They have a Dockerfile for doing this, and with docker-compose, the process is basically automatic.

#5

i just run them as cron jobs on the host. put them in small skript /usr/local/bin/nextcloud_optimize.sh and put this roots crontab.

any reason for this?

did you try to copy the cron.sh to your host, add your tasks and run the container like this:

  cron:
    image: nextcloud:apache
    restart: always
    volumes:
      - nextcloud:/var/www/html
      - /path/to/your/cron.sh:/crons.sh:ro
    entrypoint: /cron.sh
    depends_on:
      - db
      - redis
Verifying where to add cron jobs docker-compose + cron
#6

Hey guys,

as far as i can tell the crontab entry is done here. So as you can see, inside the container the file /var/spool/cron/crontabs/www-data is used and it usually contains one line like */5 * * * * php -f /var/www/html/cron.php for executing the cron.php every 5 minutes. If you want to do any additional cron tasks you could mount a custom crontab file and add any desired lines. A snippet of the corresponding docker-compose file could look like this:

cron:
    image: nextcloud:apache
    restart: always
    volumes:
      - nextcloud:/var/www/html
      - ./mycronfile:/var/spool/cron/crontabs/www-data
    entrypoint: /cron.sh
    depends_on:
      - db
      - redis

while the content of mycronfile could be something like

*/5 * * * * php -f /var/www/html/cron.php
0   0 * * 0 php -f /var/www/html/occ fulltextsearch:index

which will additionally index your NC instance once a week on sunday night at 0:00.

Verifying where to add cron jobs docker-compose + cron
Verifying where to add cron jobs docker-compose + cron
#7

Hello,

could you please show an example on how to add a task to this script?
I could not find any examples on how to use this cron.sh. It seems to be a normal bash script but then how do you add a task e.g. for preview generator (occ preview:pre-generate)? I do not understand the “exec busybox crond” line already in that file, why do you need exec?
Thanks in advance!

#8

use this script as cronjob. do not try to enable cron inside the contaier. inside any container.

so you just add docker exec --user www-data nextcloud php occ preview:pre-generate assuming that your container name is nextcloud and www-data the web server user.

just saying.

this is a way to enable crond inside a container.

exec executes everything you use as the first argument. e.g. a shell skript has no +x bit. exec that-skript is your friend. and busybox crond just starts the cron daemon inside the container.

nevertheless after i wrote the comment above i found this article in german https://www.projekt-rootserver.de/cron-events-in-docker-containern-zum-laufen-bringen/2019/09/ it says: don’t do it with busybox. not a good idea. the authors advice: use the host cron + docker exec

1 Like
#9

Thanks @Reiner_Nippes. I will then use system cron. I use this docker-compose config to run my nextcloud and since there is a docker service for cron I thought I should use that but then that’s not recommended.

#10

I just migrated my nextcloud to a docker setup on a NAS as host system. First I used the second container solution but now switched to your proposal of using a script in the host’s cron service.

Yet I have two questions that maybe you or s.o. else have answers to:

  1. Do these commands
docker exec --user www-data nextcloud php occ files:scan --all
docker exec --user www-data nextcloud php occ files:scan-app-data
docker exec --user www-data nextcloud php occ preview:pre-generate
exit 0

represent all relevant jobs which are usually done by cron.php?

  1. Does this solution have any advantage against for example calling cron.php as a webjob like e.g. https://zeitfresser.net/nextcloud-cronjob-ueber-synology-erstellen/ (de) proposes?

Oh, and a bonus question if I may:

  1. It is a tiny setup for max 5 users mainly using the cloud during daytime. So I’d like to let my NAS sleep during nighttime. A 24/7 every-15-minutes cronjob would prevent this, right? Is there any risk if I pause the cronjob during night hours ?
#11

yesterday I was fixing my cron job, cos my deployment is running in docker-compose statement, so yes, as you said, I created a cronjob into the host to call a simple:

docker exec -t -u www-data nextcloud-app php -f /var/www/html/cron.php

in fact, from my beginner understanding from all about containers, It should be better run it on this mode. We should leaves each container running its own service. :grinning: