Backups and users
-> Say I have a mattermost app with 100 users that authenticate using cloudron credentials.
-> Say I create a backup
-> Say I use this backup to migrate that app to another cloudron.
How are users mapped on the new cloudron? What is the unique key, that x, that says, user x on cloudron has access to user x on mattermost?
that authenticate using cloudron credentials.
This is afaik not possible as you would need Mattermost Enterprise to use external user sources like ldap.
In my experience, Cloudron treats user names as unique and cannot be changed. However, the information about the actual users is only contained in the box backup and is not part of the individual application backup.
So if you restore a backup from cloudron-a to cloudron-b, all users with the same name will still have access, and others that don't exist on cloudron-b would be orphaned or deleted by the software running in the application (but this depends heavily on how the actual software handles these scenarios).
Cloudron treats user names as unique
Yes, we used to uuid and then went and changed all the apps to use username so that migration from one Cloudron to another (or anywhere else) is easier. As long as the username exists on the other cloudron, user should be able to login.