Create gitlab backups in docker swarm

Hi there,
when running Gitlab CE from Omnibus on Ubuntu, I was used to create my backups via the rake-bundle - triggered by a cronjob in Ubuntu

When running the Gitlab CE within a docker container, there is no cron which can be configured.

There are some ways I think about - but no one of that seems to be exactly brilliant:

  • Running the cronjob on the hosts with docker exec - crazy way in docker swarm. You do not even know which host is running the container. Doing cronjobs on the host for running in container seems to be a bad solution. Do not want to do that.
  • Cron within the container: seems not to be there. So I would have to switch to another container image with has cron inside and build my own docker image. Possible, but is this really neccessary?
  • Doing SSH into the Gitlab Container from another container which has cron inside. seems to be the best way for me - although I have to define a ssh key for that

Are there other ways I have missed so far?