Do not use a machine-id value of uninitialized

[Cornelicorn]

Describe the bug
systemd supports writing uninitialized to /etc/machine-id, which can be used for systemd-firstboot instead of removing /etc/machine-id. Dracut does not check the contents of this file to populate MACHINE_ID, so the value unitialized is used

Distribution used
Debian bookworm (12)

Dracut version
059

Init system
systemd

To Reproduce

echo "uninitialized" > /etc/machine-id
dracut -f

Expected behavior
Dracut behaves as if there was no machine-id set, i.e. setting MACHINE_ID="Default".

Additional context

[aafeijoo-suse]

See #1873 (comment)

[Cornelicorn]

See #1873 (comment)

This issue is about /etc/machine-id on the host system, not /etc/machine-id inside the initrd.

[LaszloGombos]

@Cornelicorn

Expected behavior
Dracut behaves as if there was no machine-id set, i.e. setting MACHINE_ID="Default".

From your POV would it be appropriate to make $initdir/etc/machine-id and empty file instead setting MACHINE_ID="Default".

[Cornelicorn]

I think the reproducer would have been clearer with dracut --uefi -f, my bad.

In [dracut.sh[(https://github.com/dracutdevs/dracut/blob/master/dracut.sh#L1086#L1094), MACHINE_ID is set to the value of /etc/machine-id if ESPDIR/Default is not a directory.
My suggestion would be to only do this if the value is not uninitialized, e.g.

if [[ -d /efi/Default ]] || [[ -d /boot/Default ]] || [[ -d /boot/efi/Default ]]; then
    MACHINE_ID="Default"
elif [[ -f /etc/machine-id ]]; then
    read -r MACHINE_ID < /etc/machine-id
    if [[ "$MACHINE_ID" == uninitialized ]]; then
        MACHINE_ID="Default"
    fi
else
    MACHINE_ID="Default"
fi

Even better would be a regex check that's it's actually an UUID, the value uninitialized or empty and in the latter two cases use MACHINE_ID="Default".

[Cornelicorn]

As far as I can tell, the value of MACHINE_ID never ends up in the initrd itself, only in the filename.

[aafeijoo-suse]

Thanks for your further explanation, now the issue is clear.