[Bug 1010873] Re: Ubuntu ec2 server instance with update-notifier-common doesn't show the existing updates

[Scott Moser]

Somewhat related is bug 1010505.
In short, there is a cost in CPU time for that message, and it is non-trivial.

I have not looked exactly how the update-motd message is generated, but
CPU usage needs to be accounted for.

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https://bugs.launchpad.net/bugs/1010873

Title:
  Ubuntu ec2 server instance with update-notifier-common doesn't show
  the existing updates

Status in “byobu” package in Ubuntu:
  New
Status in “update-notifier” package in Ubuntu:
  New

Bug description:
  I'm running an Ubuntu EC2 instance: ami-e7e8d393

  When I ssh login my account, there's a welcome message containing "x
  packages can be updated. y updates are security updates." expression
  where x and y are a non-negative integers.

  I have a feeling that the mentioned expression has something to do
  with update-notifier-common package.

  There are two problems with the behaivour of the expression:

  1- Sometimes, the expression doesn't even show up. Without using some other tools, we don't know if there's an update or not.
  2- Sometimes, the expression says that "0 packages can be updated. 0 updates are security updates.", but in fact there are updates, in some cases some of them are security updates.

  For the 1st type: It seems that the system does not print anything if
  an upgrade was applied and time for the next check is not reached.

  On https://bugs.launchpad.net/ubuntu/+source/update-
  notifier/+bug/356152/comments/4 Michael Vogt states that "update-
  notiifer just checks when the last apt/dpkg action was performed and
  calcualtes the 7 days based on that". We don't have update-notifier
  package but we have update-notifier-common. Anyway, similar to what
  Vogt said, here might be such a scenario in action:

  * The system/code having something to do with update-notifier-common, whatever it is, calls for checking again at a fixed time daily (observations give me the impression that the period is no longer than daily)
  * If there are updates in between two consecutive checks
  a) It doesn't print anything at all if the last check was triggered by an actual upgrade
  b) It shows 0 and 0 if the available updates came after the last 0 and 0 situation

  Reagarding the 2nd type: Its clearly a bug. There are updates, what's
  more there are (may be) security updates and welcome mesage says "0
  updates, 0 security updates.

  Regarding the 1st type: Even if it doesn't say anything whether there
  are updates or not, even with no such expression at all, in my opinion
  this is still a bug. This notyfying expression is not added to the
  distro by the user, its among the defaults and seems not to be
  documented well (if documented at all, somewhere) and seems that for
  server version there's not a setting for it around so s/he has no idea
  on when and why its printed or not. User either thinks that everything
  is fine (there's no notification at all so no "update" warning). Or
  s/he thinks that there's something broken because the expression is
  not there anymore.

  Even after figuring out how things work (if what figured out is
  valid); user can benefit from the expression if the values are greater
  than 0, but when it says 0 and 0; it doesn't tell much (unless you are
  keeping a record and unless you are hundred percent positive that the
  0 and 0 situation is older than the check period).

  This is not the expected behaviour for an update notifier on a server.

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