[Bug 1928040] Please test proposed package

[Łukasz Zemczak]

Hello Matthew, or anyone else affected,

Accepted grub2-signed into xenial-proposed. The package will build now
and be available at
https://launchpad.net/ubuntu/+source/grub2-signed/1.167~16.04.2 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
xenial to verification-done-xenial. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-xenial. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

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https://bugs.launchpad.net/bugs/1928040

Title:
  GCE instances drop to a grub prompt when GRUB_DISTRIBUTOR=Debian is
  set

Status in grub2-signed package in Ubuntu:
  Invalid
Status in grub2-signed source package in Xenial:
  Fix Committed

Bug description:
  [Impact]

  GCE cloud instances started with images released prior to 2020-11-11
  will fail to reboot when the newest grub2 2.02~beta2-36ubuntu3.32
  packages are installed from -updates.

  Upon reboot, the instance drops down to a grub prompt, and ceases to
  boot any further.

  The output displayed is:

  BdsDxe: loading Boot0003 "debian" from HD(15,GPT,<UUID>,0x2800,0x35000)/\EFI\debian\shimx64.efi
  BdsDxe: starting Boot0003 "debian" from HD(15,GPT,<UUID>,0x2800,0x35000)/\EFI\debian\shimx64.efi

  UEFI: Attempting to start image.
  Description: debian
  FilePath: HD(15,GPT,36903981-58D9-4718-A4EC-3D3E6CF6AF42,0x2800,0x35000)/\EFI\debian\shimx64.efi
  OptionNumber: 3.

  GNU GRUB version 2.04
  grub>

  Now, on GCE cloud images prior to 2020-11-11, /etc/default/grub.d/50
  -cloudimg-settings.cfg contained this line:

  GRUB_DISTRIBUTOR=Debian

  In images after 2020-11-11, this line was REMOVED from
  /etc/default/grub.d/50-cloudimg-settings.cfg and instead, images fell
  back to the below line in /etc/default/grub

  GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`

  The above line always returns "Ubuntu".

  The new grub2 version 2.02~beta2-36ubuntu3.32 now places the EFI
  executables in the /EFI/Ubuntu directory, while the grub config points
  to /EFI/Debian, and the grub config cannot be found, and hence we drop
  to a grub shell.

  [Testcase]

  You can start an instance up on Google Cloud with an affected image
  with the below command:

  gcloud compute instances create test-xenial-1
  --image=ubuntu-1604-xenial-v20200429 --image-project=ubuntu-os-cloud

  From there:

  $ sudo apt update
  $ sudo apt install grub-common grub-efi-amd64 grub-efi-amd64-bin grub-efi-amd64-signed grub-pc-bin grub2-common
  $ sudo reboot

  The instance will not come back up, and you will see a grub shell in
  the logs on GCP.

  You can also reproduce in KVM. Simply add:

  GRUB_DISTRIBUTOR=Debian

  to a file in /etc/default/grub.d/50-cloudimg-settings.cfg then:

  $ sudo update-grub
  $ sudo reboot

  Test packages are available in the following ppa:

  https://launchpad.net/~mruffell/+archive/ubuntu/lp1928040-test

  If you install these test packages, you should be able to upgrade grub
  and reboot without issue.

  [Where problems could occur]

  We will be changing the grub configuration for every Google cloud
  instance started with an image produced before 2020-11-11, and there
  is risk that we could make a change which prevents instances from
  booting. We should proceed with caution and make sure to test older
  and newer images.

  The fix will be targeted to the /etc/default/grub.d/50-cloudimg-
  settings.cfg file only, so only cloud instances would get the change,
  and only if the grub versions match particular versions.

  [Other info]

  A workaround is to remove the below line from /etc/default/grub.d/50
  -cloudimg-settings.cfg before installing the new grub packages.

  GRUB_DISTRIBUTOR=Debian

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