Provide a way to hide / remove the system address book globally

[mbiebl]

Describe the solution you'd like

The latest version v27 introduces the system address book or more specifically exposes it to every user as a separate address book named "accounts".
This addressbook is also synced to client devices, like iOS, via CardDAV, which is something I don't want.

I'm missing a global switch to not expose this system address book for all users.

Ref #19575

[mbiebl]

To further elaborate on that point: I don't need this system address book on end devices and under iOS it has an undesired side effect: As the system address book is read-only, iOS no longer offers to use the Nextcloud CardDAV Account as default account for storing new contacts.

[ChristophWurst]

As the system address book is read-only, iOS no longer offers to use the Nextcloud CardDAV Account as default account for storing new contacts.

Do you not have any other writable address books?

[ChristophWurst]

https://docs.nextcloud.com/server/27/admin_manual/release_notes/upgrade_to_27.html#exposed-system-address-book doesn't disable the address book but the contents.

[mbiebl]

As the system address book is read-only, iOS no longer offers to use the Nextcloud CardDAV Account as default account for storing new contacts.

Do you not have any other writable address books?

I do have another, writable address book.
E.g. for my own user, I currently have
https://XXXX/remote.php/dav/addressbooks/users/michael/default/ (rw)
https://XXXX/remote.php/dav/addressbooks/users/michael/z-server-generated--system/ (ro)

[mbiebl]

https://docs.nextcloud.com/server/27/admin_manual/release_notes/upgrade_to_27.html#exposed-system-address-book doesn't disable the address book but the contents.

How do I apply/restrict those enumeration settings?
Will the read-only, system address book be gone completely or just empty?
Does this break auto-completion when using sharing?

[mbiebl]

What I'm basically asking here is a way to not expose the system address book via CardDAV.

[ChristophWurst]

I do have another, writable address book.
E.g. for my own user, I currently have
https://XXXX/remote.php/dav/addressbooks/users/michael/default/ (rw)
https://XXXX/remote.php/dav/addressbooks/users/michael/z-server-generated--system/ (ro)

And iOS won't allow you to use default as AB for storing new contacts?

The system AB uses sharing enumeration settings as privacy control. If you turn off enumeration the AB will only show the user's own contact. Autocompletion will be limited to what's allowed for the enumeration.

Hiding the full AB from the user's address book home is currently not supported.

[mbiebl]

And iOS won't allow you to use default as AB for storing new contacts?

Correct.
You can only select full CardDAV accounts, not individual address books.
And the existence of a (single) ro address book makes iOS disregard that particular CardDAV account

[ChristophWurst]

Ouch. Do you know if that also happened before the system AB when someone shared an AB read-only with you?