[Bug 1747499] Re: 98-reboot-required and Interaction with livepatch

[Brian Murray]

Hello Andreas, or anyone else affected,

Accepted update-notifier into focal-proposed. The package will build now
and be available at https://launchpad.net/ubuntu/+source/update-
notifier/3.192.30.11 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-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. 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.

** Changed in: update-notifier (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-focal

** Changed in: unattended-upgrades (Ubuntu Focal)
       Status: In Progress => Fix Committed

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https://bugs.launchpad.net/bugs/1747499

Title:
  98-reboot-required and Interaction with livepatch

Status in unattended-upgrades package in Ubuntu:
  Fix Released
Status in update-notifier package in Ubuntu:
  Fix Released
Status in unattended-upgrades source package in Focal:
  Fix Committed
Status in update-notifier source package in Focal:
  Fix Committed

Bug description:
  
  [Impact]

   * If a system is using canonical livepatch, has it enabled, and
  patches are applied, it could be confusing for a user to receive a
  "system restart required" messages in the MOTD when logging in.

   * Livepatch is available on LTS releases. Thus, the users can be
  confused following a kernel update on 20.04.

   * The upload prevents update-notifier and unattended-ugprades hooks from adding "system restart"-related messages to motd when Livepatch is enabled.
  Livepatch, when enabled, already contributes to the motd message so there is no need to have duplicate (and sometimes contradictory) information.

  [Test Plan]

   * how to reproduce the bug:

     1. Install and boot a 20.04 server VM
     2. Make sure it runs a generic kernel (or another flavour that supports Livepatch)
     3. Enable Livepatch using the following command:
         $ ua attach <token>    # replace <token> by an actual contract token
     4. Upgrade the kernel (if you are already running the latest available kernel update, you can install a different flavour)
     5. Upon logging in again, the motd will show ***System restart required***.

   * other testing appropriate to perform before landing this update:

    * Making sure that the patch has no impact when livepatch is not enabled.
    * The motd should show ***System restart required*** after upgrading the kernel if livepatch is not enabled.

  [Where problems could occur]

   * The change updates a hook script in /etc/kernel/postinst.d/.
  Scripts in this directory are executing when upgrading / installing a
  kernel. If somehow the script is broken, it can prevent dpkg for
  succeeding when upgrading / installing the kernel.

   * If the implementation is wrong, we might end up "losing" the
  ***System restart required*** message when livepatch is disabled

  [Original bug description]

  If a system is using canonical livepatch, has it enabled, and patches
  are applied, it could be confusing for a user to receive a "system
  restart required" messages in the MOTD when logging in.

  That message, when present, is printed by 98-reboot-required which
  essentially just cats /var/run/reboot-required to stdout. That file is
  placed by packages that require a reboot so that they are properly
  used in their updated versions. Examples that come to mind are libc
  and the kernel.

  There is a secondary file that can be created which says which
  packages requested the reboot. That would be /var/run/reboot-
  required.pkgs

  Ideally that script should not print out the reboot required message
  if a) livepatch is installed and enabled; b) the only trigger for the
  reboot is a kernel update.

  For (a), one can use the command "ubuntu-advantage is-livepatch-
  enabled" and check $?. That is in the ubuntu-advantage-tools package.

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