Feature request : BTRBK + grub-btrfs - Restore the snapshot currently booted - like Timeshift

[matleborgne]

Usecase description

When using grub-btrfs in addition to BTRBK, it is possible to boot on a selected snapshot in grub.

To restore a snapshot, it is then mandatory :

• either to manually select it by name or entry,
• or to select the last one by ID or with btrbk ls / command.

It is not possible to "automatically" select the current snapshot mounted on "/" to restore it.

Current workaround

My workaround is the following :

• when creating the snapshot : doing first a btrbk dryrun to get the snapshot name and logging it in /etc/btrbk/last_snapshot.log ; then doing the btrbk run to actually create the snapshot with his own name "embedded" in it,
• when restoring the snapshot : reading the value from /etc/btrbk/last_snapshot.log as the entry.

This works as intended, because the /etc/btrbk/last_snapshot.log in the snapshot is the one just before the snapshot was actually made (overwritten with each snapshot).

However, this is not a "clean way" to do it, as I have to set "timestamp_format short" to avoid logging a wrong name, and not lauching the full command near to midnight as it could as well logging a wrong name.

Precision : Neither blkid, lsblk, mount or findmnt -like commands seems to be able to know we booted on a btrfs snapshot, which seems strange (but I'm not a btrfs expert). This is why I let down the idea of getting the current booted snapshot name during the restoring phase.

EDIT : I found another workaround using dmesg boot logs, which has to be done from the snapshot itself.

dmesg | grep "Command line"