Well today the issue was that I wanted to do a fresh install as I had some weird 2.4.0-betaXYZ which wouldn’t update on it’s own. I did a test on another VM with a clean install and restoring the backup to 2.7.12 which worked perfectly (also split the data container into redis and postgres).
Now the main server was still running an old Ubuntu and old Docker, so I wanted to
- take a backup
- shutdown Discourse
- do OS upgrade shenanigans without worrying about Discourse including several reboots
- Do a fresh installation
- Restore the backup
I just wanted to keep the containers off and do not delete them right away, as I wasn’t sure anymore if I needed anything from them which I might had forgotten during my test. And I just thought, hey, unless-stopped is to me the perfect restart policy as it makes sure the containers come up after reboot automatically just unless you manually stop them. Usually exactly what I want, so i thought why not trying to make that permanent.
It’s not a big deal if it’s not possible. 
Will just do the docker update (or if I keep forgetting it too often do the docker update via cron every 5 min 
)