[SRU] minimize number of manually installed packages

[Julian Andres Klode]

[Impact]
Releases prior to cosmic mark almost all packages manually installed, meaning that obsolete packages are not autoremoved when they should. We fixed this in cosmic, in trunk r1695, by including a new script that marks as automatically installed all dependencies of manually-installed metapackages.

[Test case]
Run a build and check in the log that some packages are visited by the script in more than one iterations.

[Regression potential]
First of all, this does not change existing installations; only new ones. The change can cause packages to be autoremoved that were not autoremoved before after performing a package management operation, or dependency change in packages.

The change is essentially safe: Since we only mark dependencies of packages in the section "metapackages", and since those receive special treatment by apt:

1. removal due to dependencies/conflicts: the manual bit transfers from the meta to its deps
2. explicit removal (apt remove meta): meta and its dependencies are removed

It is not possible to accidentally uninstall the entire metapackage with its dependencies.

[Julian Andres Klode (juliank)]

This is blocked by bug 1801629

[Amr Ibrahim (amribrahim1987)]

Could this be related to bug #1806204?

[Timo Aaltonen (tjaalton)]

Hello Julian, or anyone else affected,

Accepted livecd-rootfs into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/livecd-rootfs/2.525.20 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 and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. 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.

[Julian Andres Klode (juliank)]

I looked at today's xubuntu daily image:

(1) Packages were being visited by the auto marker
(2) The built image has a lot of automatically marked packages, as we want
(3) Crucially, cryptsetup and lvm2 are still manual, so we avoid the regression from 1801629

-> Verified.

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for livecd-rootfs has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package livecd-rootfs - 2.525.20

---------------
livecd-rootfs (2.525.20) bionic; urgency=medium

  [ Steve Langasek ]
  * Drop /etc/update-motd.d/51-cloudguest from cloud images; this is not
    consistent with current Ubuntu Advantage product language. Any future
    customizations to update-motd for cloud images should be done via a
    package instead.

  [ Julian Andres Klode ]
  * Minimize the number of manually installed packages in images by marking
    dependencies of metapackages as automatically installed. (LP: #1800610);
    but do not mark direct dependencies of ubiquity as auto installed. This
    caused cryptsetup to remain auto on the installed system in bionic (see
    LP #1801629)

 -- Steve Langasek <email address hidden> Thu, 14 Mar 2019 11:04:49 -0700

[Adam Conrad (adconrad)]

I initially marked this Won't Fix for xenial, as there will be no more desktop or server images produced for xenial, but if this also has benefit on cloud images, we might want to look into it for that.