needrestart causes kernel upgrade messages in motd

[Robie Basak]

[Impact]
needrestart shouldn't be writing to /run/reboot-required for kernel updates, that should be reserved to update-manager

[Test plan]

We can use the mockuname thing from the autopkgtests to simulate a kernel
version mismatch:

# in a fresh VM
pull-lp-source needrestart noble
cd needrestart-3.6
gcc -shared -fPIC -ldl debian/tests/mockuname.c -o mockuname.so
LD_PRELOAD=$PWD/mockuname.so apt install hello
# needrestart should complain that the system should be restarted
test ! -x /run/reboot-required || echo test failed

[Where problems could occur]

That particular patch seems on the safer side, nothing in the code relies on this file being written to.

[Original report]

On Noble, I see this in my motd:

*** System restart required ***
Pending kernel upgrade!
Running kernel version:
  6.8.0-22-generic
Diagnostics:
  The currently running kernel version is not the expected kernel version 6.8.0-31-generic.

I found this code in needrestart:

/usr/sbin/needrestart: 'The currently running kernel version is {kversion} which is not the expected kernel version {eversion}.',

I'm told that it is incorrect for needrestart to be injecting this into motd. Steve points out that needrestart isn't installed on desktop and the behaviour shouldn't be different here, thinks that this shouldn't be injected into motd, and asked for a bug report for this.

needrestart 3.6-7ubuntu4

[Robie Basak (racb)]

Steve asked for this to be Critical and assigned to Simon.

[Steve Langasek (vorlon)]

Simon, I don't know if this is a regression in noble, but for sure it shouldn't be needrestart telling us about kernel updates - we already have update-notifier for this which, crucially, is livepatch aware.

[Simon Chopin (schopin)]

This is a new feature that I implemented based on what I had understood were the requirements: integrating needrestart with /run/reboot-required. Apparently, MOTD picks up whatever we write in that file.

Shall I walk that part back and not write to that file in the case of kernel updates? I suppose needrestart could also go through update-notifier and mimick the kernel postinst code somehow?

[Launchpad Janitor (janitor)]

This bug was fixed in the package needrestart - 3.6-8ubuntu3

---------------
needrestart (3.6-8ubuntu3) oracular; urgency=medium

  * d/p/ubuntu-mode.patch: Don't touch /run/reboot-required on kernel updates
    (LP: #2065863)
  * Ubuntu mode: disable it if restart mode has been explicitly set
    (LP: #2068543)
  * Add some inline documentation for the Ubuntu mode (LP: #2068573)
  * Don't restart the google-guest-agent service (LP: #2063442)
  * Don't restart the GH runner provisioner (LP: #2067800)
  * tests: guard against looping when failing.

 -- Simon Chopin <email address hidden> Fri, 14 Jun 2024 11:57:11 +0200