According to the systemd documentation[1], if /etc/machine-id is empty
it will be populated with a unique value, but not in a way which
triggers an actual first boot event (running units with
ConditionFirstBoot=yes set)
This change writes "uninitialized" to /etc/machine-id to ensure that
systemd-firstboot.service actually runs, and other units can use
first-boot-complete.target as a dependency to trigger on first boot.
Since /var/lib/dbus/machine-id is sometimes a symlink to
/etc/machine-id, it is truncated before writing to /etc/machine-id.
On older versions of systemd before first boot semantics were
formalised, any non-uuid value will trigger a new machine-id to be
generated, so "uninitialized" also works.
[1] https://www.freedesktop.org/software/systemd/man/machine-id.html#First%20Boot%20Semantics
Change-Id: I77c35e51a3da2e8a6b5a2c80d033a159b303c9af
This reverts I2701260d54cf6bc79f1ac765b512d99d799e8c43,
Idf2a471453c5490d927979fb97aa916418172153 and part of
Iecf7f7e4c992bb23437b6461cdd04cdca96aafa6 which added special flags to
update kernels via grubby.
These changes actually ended up reverting the behaviour on Fedora 35,
which is what led me to investigate what was going on more fully.
All distros still support setting GRUB_DEVICE in /etc/default/grub;
even the BLS based ones (i.e. everything !centos7).
The implementation *is* confusing -- in earlier distros each BLS entry
would refer to the variable $kernelopts; which grub2-mkconfig would
write into /boot/grub2/grubenv. After commit [1] this was reverted,
and the kernel options are directly written into the BLS entry.
But the real problem is this bit from [2]
get_sorted_bls()
{
if ! [ -d "${blsdir}" ] || ! [ -e /etc/machine-id ]; then
return
fi
...
files=($(for bls in ${blsdir}/${machine_id}-*.conf; do
...
}
i.e., to avoid overwriting BLS entries for other OS-boots (?),
grub2-mkconfig will only update those BLS entries that match the
current machine-id.
The problem for DIB is that we are clearing the machine-id early in
finalise.d/01-clear-machine-id, but then running the bootloader update
later in finalise.d/50-bootloader.
The result is that the bootloader entry generated when we installed
the kernel (which guessed at the root= device, etc.) is *not* updated.
Even more annoyingly, the gate doesn't pick this up -- because the
gate tests run on a DIB image that was booted with
"root=LABEL=cloudimg-rootfs" the kernel initially installed with
"install-kernel" (that we never updated) is actually correct. But
this fails when built on a production host.
Thus we don't need any of the explicit grubby updates; these are
reverted here. This moves the machine-id clearing to after the
bootloader setup, which allows grub2-mkconfig to setup the BLS entries
correctly.
[1] 4a742183a3
[2] https://src.fedoraproject.org/rpms/grub2/blob/rawhide/f/0062-Add-BLS-support-to-grub-mkconfig.patch
Depends-On: https://review.opendev.org/c/zuul/nodepool/+/818705
Change-Id: Ia0e49980eb50eae29a5377d24ef0b31e4d78d346
2021-11-25 14:26:23 +11:00
Renamed from diskimage_builder/elements/sysprep/finalise.d/01-clear-machine-id (Browse further)
