Support application-specific backups/restores

[Michael Terry]

From https://answers.edge.launchpad.net/deja-dup/+question/57484 by Maximilian Blömer:

"Also it would be great to manage the backup of applications configurations and data like firefox bookmarks, evolution emails, tomboy notices or simply the picture-, music-, whatever-folder in a way other people can easy add backup and restore settings for single applications. So there can be similar to the include-list a list of applications (their settings and data) you want to backup without need to know where those email or bookmark-files are stored. Of course the user easily can "restore only emails" or "restore only bookmars" from a backup."

This would become difficult to manage ourselves. It might dovetail with bug 306983. That is, maybe we could allow third-party applications to drop a file somewhere that specifies which files would be useful to backup that they own.

Ideally, however, the user wouldn't need to bother. I feel like the naive user would accept the default "backup the entire home directory" approach and only exclude what they don't want. Which would pull in any and all application data.

So if the user backs up their whole home directory, we don't really need this feature. But if the user doesn't back it all up, and wants to backup only certain applications, they may miss lots of good stuff that they didn't know they wanted. I suspect it's better to default to including everything.

But even including everything by default, I suppose it would be useful to allow the user to exclude applications from the backup. So this would still be useful.

[mb (maxbloemer)]

even when you alsways backup your entire home directory, you maybe only want to restore the applicastion data from a single applications without wanting to know where those files are stored.

[Michael Terry (mterry)]

Good point.

[Huygens (huygens-25)]

I think that this is not a Déjà Dup problem, this is global. Perhaps, at the level of Ubuntu should be defined a sort of Backup Service (a daemon that does not do backup itself, but application register to it). Then, application could implement the API of this Backup Service and tell what application data should be backup or not. Then, a backup application should also implement this API and request the Backup Service what application data shall be backup.
The user would have to select in the backup application if he wants to save application data and which specific folders does he wants to backup.

[Michael Terry (mterry)]

I’m moving all the suggestions for more advanced include/exclude support to a single ticket on Gitlab

https://gitlab.gnome.org/World/deja-dup/-/issues/112