[Bug 1836475] Re: [SRU] update-notifier-common weekly cron job runs at the same time for all computers across the globe

[Robie Basak]

Here are some regression scenarios:

Someone has taken control of all scheduled tasks on a load-critical
server by either disabling cron, adjusting the cron.weekly job, or
adjusting this particular weekly job in cron. Switching to a systemd
timer and enabling it by default would disrupt such a user.

Someone doesn't want the outbound traffic (eg. on privacy grounds) and
has disabled the job via cron. Again, this might have happened at
various points in cron's configuration.

> I'm keen to try and avoid handling any more complex (arbitrary)
customisations

I agree! I think I prefer adding a random sleep for the SRU for this
reason, even if the appropriate fix for the development release that
landed in Groovy was to switch to a systemd timer. However a long random
sleep in cron.weekly will hold up other cron.weekly jobs, so given that
/usr/lib/ubuntu-release-upgrader/release-upgrade-motd already gates with
a timestamp, perhaps backgrounding a shorter random delay would be
preferable if that would be acceptable to Canonical IS?

I would want to refer to other SRU team members before making a
decision. If somebody is opposed to the random delay method, a systemd
timer can still work, but in that case breaking the above use cases
should be deliberate and documented.

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https://bugs.launchpad.net/bugs/1836475

Title:
  [SRU] update-notifier-common weekly cron job runs at the same time for
  all computers across the globe

Status in update-notifier package in Ubuntu:
  Fix Released
Status in update-notifier source package in Focal:
  Triaged
Status in update-notifier source package in Groovy:
  Fix Released

Bug description:
  [Impact]

  * The fix spreads access to changelogs.ubuntu.com over a full week (it was decided this was preferable to the 24h originally requested)
  * This results in reduced load on Canonical's infrastructure, of benefit to all users

  [Test Case]

  On Focal desktop and server installations:

  * sudo add-apt-repository ppa:waveform/update-notifier
  * sudo apt update
  * sudo apt install update-notifier-common
  * Ensure that /etc/cron.daily/update-notifier-common and /etc/cron.weekly/update-notifier-common have been removed
  * Ensure systemctl status update-notifier-motd.timer shows a valid timer
  * Ensure systemctl status update-notifier-download.timer shows a valid timer

  [Regression Potential]

  Low; the patch is already in active use in Groovy.

  [Original Description]

  Hi,

  /etc/cron.weekly/update-notifier-common is run at the same time on all
  machines across the globe. It's putting unnecessary stress on
  Canonical's infrastructure (changelogs.ubuntu.com, specifically).
  Could we please have this job spread out over 24h ?

  And could we please SRU this change ?

  Thanks

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