[Bug 1619188] Re: Unattended upgrades can break persistent live media

[sudodus]

Even if it works for you with a live seesion, it does not work for me
with a persistent live session using a casper-rw partition. starting
from the Ubuntu 16.04.1 LTS iso file. I don't think mkusb has anything
at all to to with this functionality because it does not touch the
mechanism (unless you tell it to do it, and then it will prevent
unattended upgrades).

mkusb has a work-around feature, and I think all other tools and manual
methods, that create persistent live drives will need some work-around
to avoid this problem. For example, if you create a cloned system with
the Ubuntu Startup Disk Creator, the cloned result will be exactly like
cloning with mkusb. It is possible in such cases to create persistence
by using a casper-rw partition (or file) in another drive. I will test
tonight, if such a system is also vulnerable to this bug.

I plan to start the test from the Ubuntu 16.04.1 LTS desktop amd64 iso
file. I intend to upgrade casper, but no other program package unless
you advice what must also be upgraded for your fix to work.

But don't tell me that I must try with the current daily iso file,
because then I would have to test for a very long period of time for
something to happen. In that case (if you know things have changed to
the better, but don't know which program packages are involved) maybe I
should zsync today's daily iso file and keep it for some weeks before I
start it and let it run for at least 24 hours.

The important thing here is to get something working for the next point
release, 16.04.2 LTS, so I think it should be tested thoroughly.

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https://bugs.launchpad.net/bugs/1619188

Title:
  Unattended upgrades can break persistent live media

Status in casper package in Ubuntu:
  Fix Released
Status in casper source package in Xenial:
  Fix Committed
Status in casper source package in Yakkety:
  Fix Released

Bug description:
  Test Case
  ---------
  1) Boot an Ubuntu 16.04 Live CD
  2) Choose Try Ubuntu
  3) head -n5 /etc/apt/apt.conf.d/50unattended-upgrades
  4) Observe -security is enabled in line 3.  (// is a comment)
  5) Run /usr/lib/apt/apt.systemd.daily
  6) Observe your Live environment run out of space! (I received a pop-up re lack of free space and /var/log/unattended-upgrades/unattended-upgrades-dpkg.log contained an error installing a package due to disk full.)

  With the version of the package in -proposed step 4 will reveal the
  -security pocket being disabled and step 6 won't fill your live
  environment.

  Regression Potential
  --------------------
  Persistent live users will not receive updates from -security, but that seems less bad than destroying people's live environment by filling up their disk.

  Original Bug Description
  ------------------------
  Looking at the persistent live Ubuntu 16.04 LTS system - the Software & Updates screen / Update - I notice, that Automatic updates is set to 'Download and install automatically'. This is bad in a persistent live system.

  After leaving the persistent live Ubuntu 16.04 LTS system running
  overnight, I found that it had performed an automatic upgrade:

  df revealed that the content in casper-rw had increased to 1.6 GiB.

  It was a surprise that the persistent live system started an automatic
  upgrade. This is not caused by the installer (mkusb), because the
  files controlling those actions are not touched. Instead it is caused
  by a change of the default action, when there are security updates.
  And the survey indicates that this default setting is different
  between the flavours and versions of Ubuntu. Lubuntu keeps the setting
  'Display immediately', while the other tested flavours change it from
  14.04 LTS to 16.04 LTS.

  Until this is resolved, it is a good idea to disable unattended-
  upgrades manually, but above all, to take regular backups, when you
  use a persistent live system.

  The survey is described in this link to the Ubuntu Forums:

  https://ubuntuforums.org/showthread.php?t=2335669&p=13538805#post13538805

  and it contains some screenshots illustrating the settings manager for
  automatic updates for different versions and flavours of Ubuntu.

  -o-

  There are various scripts in the casper package that change things to
  be more appropriate for the live environment. I suggest to change the
  default for security updates to 'Display immediately', when the system
  is running live and persistent live.

  See also this link to Ask Ubuntu, the first report about this problem:

  https://askubuntu.com/questions/817750/unattended-upgrades-broke-
  persistent-live-media/817820#

  -o-

  Addendum: Things should continue to work if you leave a live Ubuntu
  iso running for a day or two. Unattended upgrades cause problems for
  all live systems, 'live-only' and 'persistent live'.

  ProblemType: BugDistroRelease: Ubuntu 16.04
  Package: casper 1.376
  ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
  Uname: Linux 4.4.0-31-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.1
  Architecture: amd64
  CasperVersion: 1.376
  CurrentDesktop: Unity
  Date: Thu Sep  1 08:32:08 2016
  LiveMediaBuild: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bashSourcePackage: casper
  UpgradeStatus: No upgrade log present (probably fresh install)

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