I did an upgrade on two droplets on DO for a client. I had a bit of an issue with Docker that I had to reinstall on one droplet (I didn’t do the install and I had trouble with Docker on this droplet before that) but other than that, it went well on both. No trouble with the database or anything else. If you do a backup or even better a snapshot, you don’t have to worry.
The duration was about 15 minutes. The forum is still running the first minutes, but not for the rest.
If I remember correctly, you may have to do a
cd /var/discourse
./launcher restart app
After the upgrade, but I’m not sure.