[Bug 1958668] Autopkgtest regression report (ubuntu-release-upgrader/1:22.04.12)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted ubuntu-release-upgrader (1:22.04.12) for jammy have finished running.
The following regressions have been reported in tests triggered by the package:

ubuntu-release-upgrader/1:22.04.12 (ppc64el, s390x)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/jammy/update_excuses.html#ubuntu-release-upgrader

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/1958668

Title:
  Do not propose to reboot on WSL

Status in ubuntu-release-upgrader package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader source package in Jammy:
  Fix Committed

Bug description:
  [Impact]

  - On WSL, at the end of a do-release-upgrade, the upgrader proposes to
  reboot the machine. On WSL it is not possible to reboot due to the
  lack of systemd, thus this causes an error message to appear, and the
  reboot to not happen.

  - The fix solves this by:
      1. Not atemptiong to reboot
      2. Asking the user to close the WSL instance
  - Furthermore, if the Ubuntu WSL launcher is recent enough:
      3. ubuntu-release-upgrade will signal the Ubuntu WSL launcher to shutdown WSL right after closing

  [Test Plan]

  - Open ubuntu WSL
  - Run do-release-upgrade -p
  - Old behaviour: Error message:
   "System has not been booted with systemd as init system (PID 1). Can't operate."

  - New behaviour:
      1. You'll be asked to close all other instances of Ubuntu WSL.

      2. File /proc/sys/fs/binfmt_misc/WSLInterop will be created with contents
                   "action: reboot"

      3. You'll be asked to close the current instance of Ubuntu WSL.

      4. If you have the store verion of Ubuntu WSL nothing else will happen.
         If you have the latest version from the repository, Ubuntu WSL will
         shutdown right after. You can validate it via:
            A. Not complying in step 1, and seeing the other instances shut down.
            B. Place some file in /tmp/ and see how it has been removed.

  [Where problems could occur]

  - Any change whatsoever in program behaviour on Ubuntu Desktop is undesired,
    especially if it prevents Ubuntu Desktop from rebooting.

  - If the Ubuntu WSL instance that we upgarde from was started without the launcher (e.g via VS code, or with "wsl -d Ubuntu2204LTS"), the shutdown will not happen immediately, but rather be posponed until whichever comes first:
     - All instances are closed for around 10 seconds
     - A Ubuntu WSL instance started with the launcher is closed.
  This could be a bit annoying for the user but it's not fatal.

  [Other Info]

  - The launcher involvement is needed because WSL doesn't shut down
  when all instances of a distro are closed. Rather, it waits for around
  ten seconds. The launcher is in charge of forcing this shutdown. The
  reboot is automatic when opening a new instance.

  - Step 1 in the "Test Plan > New behaviour" part is purely for user-experience, it is unnecessary otherwise. When Ubuntu WSL shuts down, all open instances will show an error message and stop working. We ask users to close other instances:
   - To hide the expected error message from them, so as not to worry them.
   - To ensure no unsaved work is open in one of the open instances, hence avoiding
     data loss.

  - A sufficiently new version of the launcher is needed for the forced shutdown to
    occur. It is currently only with the Github version, but it'll be part of store
    versions from the next release onwards.

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