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

Thu Oct 27 18:36:17 UTC 2016

The tests started yesterday can be described like this:

1. I tested the Ubuntu 16.04.1 LTS desktop amd64 iso file.

2. To be completely sure, I created two USB boot drives with the Ubuntu
Startup Disk Creator (not that it would clone differently from mkusb,
but anyway, just in case.

3. I upgraded casper to the new version in xenial-proposed, 1.376.2.

4. I ran both tests in UEFI mode, a live-only session in an Intel NUC

https://www-ssl.intel.com/content/www/us/en/nuc/nuc-kit-nuc6i3syh.html

and a persistent live session in a Lenovo X131e

https://shop.lenovo.com/ISS_Static/ww/wci/products/us/laptop/thinkpad/x-series
/x131e-intel/X131e-Datasheet-Intel.pdf

The persistence was using a casper-rw partition in another drive
(because the cloned drive has the read-only file system ISO 9660.

I checked with 'df -h' how much space was used before and after the test
period.

5. Result

Live-only:

ubuntu at ubuntu:~$ date;df -h .
Wed Oct 26 17:46:20 UTC 2016
Filesystem      Size  Used Avail Use% Mounted on
/cow            1.9G   48M  1.9G   3% /
ubuntu at ubuntu:~$ echo 'this is live-only'
this is live-only
ubuntu at ubuntu:~$ echo 'this is live-only'
this is live-only
ubuntu at ubuntu:~$ date;df -h .
Wed Oct 26 19:38:35 UTC 2016
Filesystem      Size  Used Avail Use% Mounted on
/cow            1.9G   48M  1.9G   3% /
ubuntu at ubuntu:~$ date;df -h .
Thu Oct 27 16:30:19 UTC 2016
Filesystem      Size  Used Avail Use% Mounted on
/cow            1.9G  1.1G  886M  54% /
ubuntu at ubuntu:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            1.9G     0  1.9G   0% /dev
tmpfs           384M  6.4M  378M   2% /run
/dev/sdb        1.5G  1.5G     0 100% /cdrom
/dev/loop0      1.4G  1.4G     0 100% /rofs
/cow            1.9G  1.1G  886M  54% /
tmpfs           1.9G  172K  1.9G   1% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
tmpfs           1.9G  4.0K  1.9G   1% /tmp
tmpfs           384M  124K  384M   1% /run/user/999
/dev/mmcblk0p2  6.0M     0  6.0M   0% /media/ubuntu/Firmware

Persistent live:

ubuntu at ubuntu:~$ date;df -h .
Wed Oct 26 18:39:29 UTC 2016
Filesystem      Size  Used Avail Use% Mounted on
/cow             22G   92M   21G   1% /
ubuntu at ubuntu:~$ date;df -h .
Thu Oct 27 16:29:50 UTC 2016
Filesystem      Size  Used Avail Use% Mounted on
/cow             22G  1.1G   20G   6% /
ubuntu at ubuntu:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            1.9G     0  1.9G   0% /dev
tmpfs           380M  6.2M  374M   2% /run
/dev/sda        1.5G  1.5G     0 100% /cdrom
/dev/loop0      1.4G  1.4G     0 100% /rofs
/cow             22G  1.1G   20G   6% /
tmpfs           1.9G  228K  1.9G   1% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
tmpfs           1.9G  4.0K  1.9G   1% /tmp
tmpfs           380M   92K  380M   1% /run/user/999
/dev/mmcblk0p5   22G  1.1G   20G   6% /media/ubuntu/casper-rw
/dev/mmcblk0p3  6.4G  2.1G  4.0G  34% /media/ubuntu/root

6. Conclusion

In both cases, a big unattended upgrade was performed. The used space
increased

from 48M to 1.1G in the live-only case and
from 92M to 1.1G in the persistent live case.

I attach the terminal dialogues in both cases for more details (in this
comment and the next one).

** Attachment added: "live-only-terminal-dialogue.txt"
   https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1619188/+attachment/4768325/+files/live-only-terminal-dialogue.txt

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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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