Ubuntu
livecd-rootfs package

Please ship empty /etc/fstab in LXD images

Bug #1877078 reported by Balint Reczey
12
This bug affects 2 people
Affects Status Importance Assigned to Milestone
livecd-rootfs (Ubuntu)
Fix Released
Undecided
Unassigned
systemd (Ubuntu)
Invalid
Undecided
Unassigned

Bug Description

Systemd boots degraded because of the invalid content of /etc/fstab:

$ lxc shell gg-test
root@gg-test:~# systemctl is-system-running
degraded
root@gg-test:~# systemctl list-units --failed
  UNIT LOAD ACTIVE SUB DESCRIPTION
● systemd-remount-fs.service loaded failed failed Remount Root and Kernel File Systems

LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB = The low-level unit activation state, values depend on unit type.

1 loaded units listed.
root@gg-test:~# cat /etc/fstab
LABEL=cloudimg-rootfs / ext4 defaults 0 0
root@gg-test:~# echo "" > /etc/fstab
root@gg-test:~# reboot

Session terminated, killing shell... ...killed.
rbalint@yogi:~$ lxc shell gg-test
root@gg-test:~# systemctl is-system-running
running
root@gg-test:~# systemctl list-units --failed
  UNIT LOAD ACTIVE SUB DESCRIPTION
0 loaded units listed.

Not shipping is also fixing the issue, but some programs (such as systemd autopkgtes) reads fstab and a missing fstab should be special-cased, thus that would cause more breakages.

Related branches

~rbalint/livecd-rootfs:empty-fstab-in-lxd
Dimitri John Ledkov (community): Approve
Ubuntu Core Development Team: Pending requested
Diff: 89 lines (+20/-10)
6 files modified
live-build/auto/config (+1/-0)
live-build/functions (+11/-0)
live-build/squashfs-exclude-files (+1/-0)
live-build/ubuntu-cpc/hooks.d/base/root-squashfs.binary (+5/-4)
live-build/ubuntu-server/hooks/030-root-squashfs.binary (+1/-3)
live-build/ubuntu-server/hooks/032-installer-squashfs.binary (+1/-3)
Francis Ginther (fginther)
tags: added: id-596e17fac6e5ac8ded74a8ee
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package livecd-rootfs - 2.668

---------------
livecd-rootfs (2.668) groovy; urgency=medium

  [ Łukasz 'sil2100' Zemczak ]
  * Enable overrides of UC20 grade dangerous channels - as this is possible.
    (LP: #1879350)

  [ Patrick Wu ]
  * live-build/ubuntu/hooks/040-hyperv-desktop-images.binary: fix issues
    with Hyper-V xrdp support.

  [ Balint Reczey ]
  * Remove fstab from squashfs images (LP: #1877078)

 -- Dimitri John Ledkov <email address hidden> Tue, 23 Jun 2020 15:05:11 +0100

Changed in livecd-rootfs (Ubuntu):
status: New → Fix Released
Revision history for this message
Balint Reczey (rbalint) wrote :

This change got reverted in livecd-rootfs and now breaks systemd autopkgtest.

livecd-rootfs (2.683) groovy; urgency=medium

  * Revert the removal of fstab from squashfs images, which has had knock-on
    effects and breaks MAAS (ref bug #1890803)

 -- Steve Langasek <email address hidden> Wed, 12 Aug 2020 11:31:12 -0700

IMO LXD images should not contain invalid fstab and MAAS should be fixed.

Changed in livecd-rootfs (Ubuntu):
status: Fix Released → Triaged
tags: added: update-excuse
Changed in systemd (Ubuntu):
status: New → Triaged
Revision history for this message
Balint Reczey (rbalint) wrote :

@vorlon What is your plan regarding this fix? The revert may have helped MAAS, but broke all LXD instances. IMO if MAAS relied on having a broken fstab then MAAS should be fixed and not LXD images should be broken, so I'd prefer having this fix in again. Maybe with /etc/fstab as an empty file which is not particularly beautiful, but not invalid at least.

Revision history for this message
Steve Langasek (vorlon) wrote : Re: [Bug 1877078] Re: Please ship empty /etc/fstab in LXD images

On Tue, Aug 25, 2020 at 02:20:50PM -0000, Balint Reczey wrote:
> @vorlon What is your plan regarding this fix? The revert may have helped
> MAAS, but broke all LXD instances. IMO if MAAS relied on having a broken
> fstab then MAAS should be fixed and not LXD images should be broken, so
> I'd prefer having this fix in again. Maybe with /etc/fstab as an empty
> file which is not particularly beautiful, but not invalid at least.

MAAS images were broken because cloud-init could not handle the new
behavior. This is not the MAAS team's responsibility to fix, the Server
Team has been working on it with Dimitri; and having our MAAS images broken
was an unacceptable regression that was blocking kernel testing.

See the other linked bug, LP: #1890803, for details. If the
cloud-initramfs-tools change has landed, then the livecd-rootfs revert can
be reverted again.

Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package livecd-rootfs - 2.686

---------------
livecd-rootfs (2.686) groovy; urgency=medium

  [ Dan Streetman ]
  * use python3-launchpadlib directly instead of python3-software-properties

  [ Steve Langasek ]
  * Restore the removal of fstab from squashfs images, now that cloud-init
    has been fixed (LP: #1877078; ref bug #1890803)

 -- Steve Langasek <email address hidden> Thu, 27 Aug 2020 08:53:31 -0700

Changed in livecd-rootfs (Ubuntu):
status: Triaged → Fix Released
Balint Reczey (rbalint)
Changed in systemd (Ubuntu):
status: Triaged → Invalid
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