Docker: Run Cronjob for different Container

best practicescrondocker

I am looking for best practices about running cronjobs for my php fpm container.

Right now running:

  • NGINX Container
  • PHP FPM Container
  • MySQL Container

I now would love to have another Container running called "Cronjob Container" who exec`s a script within my PHP FPM Container ( I need some dependencies of PHP ).

So three possible solutions:

1.) Running an own container

I would love to use this solution!

It would be good to have a container running CRON where I am able to ( somehow ) call docker exec on my php fpm container… Or have another way.

2.) Running CRON inside of PHP Container

This would be okay, but is not best practice. I could start a second process inside my php fpm container running cron. This would work but I am not sure if this is who you should work with docker.

3.) Running Hosts Cron

This would be cruel. I would need to find the processID and containerID of a given path and then run docker exec. But this is more or less my last way… And I hate to manage cronjobs without of deployment.

So what is the best approach here?

Have a nice day,

Bastian

Best Answer

I've written a daemon that observes containers and schedules jobs, defined in their metadata, on them. This comes closest to your 1) solution. Example:

version: '2'

services:
  wordpress:
    image: wordpress
  mysql:
    image: mariadb
    volumes:
      - ./database_dumps:/dumps
    labels:
      deck-chores.dump.command: sh -c "mysqldump --all-databases > /dumps/dump-$$(date -Idate)"
      deck-chores.dump.interval: daily

'Classic', cron-like configuration is also possible.

Here are the docs, here's the image repository.

Related Topic