However, when I run sudo gitlab-ctl start several of the services fail to start. some seem to quit and restart, as I’ve restarted several times and the list seems to be different every time.
You should really be using the Gitlab Backup and Restore procedures outlined in the Gitlab docs. Using rsync is hit-and-miss at best due to the fact, the UID/GID of your accounts under Mint20 will be different for Gitlab under Mint21. You can check/verify that by looking at /etc/passwd on both machines, as well as /etc/group.
If you had a backup, you would restore the backup as per the Gitlab restore procedures which would more or less be:
Install Gitlab on Mint 21.
Copy /etc/gitlab/gitlab.rb and /etc/gitlab/gitlab-secrets.json from Mint20 to Mint21.
Run gitlab-ctl reconfigure
Follow Gitlab restore docs to restore backup which will exist under /var/opt/gitlab/backups on Mint 20 - copy that to /var/opt/gitlab/backups on Mint21, and use restore procedures.
I tried that, it didn’t work either. That procedure seems to be written from the perspective that I am migrating between 2 machines. I’m not. When I’m booted into mint21, mint20 is obviously not running, so there is no need to stop, modify settings, reconfigure, etc on mint20. Mint21 was stopped. I can’t see why copying the files won’t work unless I missed something.
Those instructions also entirely left out the restore step. It talks about copying the files over and running reconfigure, then - nothing else.
I see your point about the account uid/gid. I’ll have to check that, although they seemed to be the same.
Except that you are. Just because Mint20 and Mint21 are on the same machine, they are still two different operating systems that are not running at the same time - which you already mentioned. Dual-booting on the same machine doesn’t change the fact that it is two separate Linux installations. The fact you need to run it under Mint21, means it is no different than a machine migration, or using backup/restore as per the docs.
The instructions for restore are in the docs: Restore GitLab | GitLab which was two options lower on the menu from the original link that I gave you. And in particular other than the config copying, this direct to the particular section: Restore GitLab | GitLab
If the UID/GID are the same, then there is no reason why it shouldn’t work. Either way, you still have to install the gitlab-ce or gitlab-ee package - whichever version you were using under Mint20, and it must be the exact same version for it to run under Mint21 and be able to restore it.
The procedures for backup/restore do work, because I’ve used them countless times already myself as have many others.
In theory, assuming UID/GID are the same, and files are copied with rsync correctly, there should be no reason that it doesn’t work. You do need gitlab-ce or gitlab-ee installed first, before doing the rsync since there are systemd scripts as well. Just copying directories is not enough. People have done it and it has worked, however it never worked for me and I’ve never tried since, because the backup/restore always works and is far easier than messing around with rsync, etc. But each have their own preferences on what they like best
