[Bug 1158686] Re: When restarting avahi-daemon cups does not reconnect to it - workaround

[Dmitrijs Ledkovs]

Looks correct sequence of events to me, this is avahi-daemon restart:
1       2013-03-22 10:22:12.696810      stopping JOB='avahi-daemon' INSTANCE='' RESULT='ok'
2       2013-03-22 10:22:12.704692      stopping JOB='cups-browsed' INSTANCE='' RESULT='ok'
3       2013-03-22 10:22:12.705150      starting JOB='cups-browsed' INSTANCE=''
4       2013-03-22 10:22:12.705537      started JOB='cups-browsed' INSTANCE=''
5       2013-03-22 10:22:12.705920      starting JOB='avahi-daemon' INSTANCE=''
6       2013-03-22 10:22:12.706322      stopping JOB='cups-browsed' INSTANCE='' RESULT='ok'
7       2013-03-22 10:22:12.706703      starting JOB='cups-browsed' INSTANCE=''
8       2013-03-22 10:22:12.712707      started JOB='cups-browsed' INSTANCE=''
9       2013-03-22 10:22:12.720260      starting JOB='avahi-cups-reload' INSTANCE=''
10      2013-03-22 10:22:12.720981      started JOB='avahi-cups-reload' INSTANCE=''
11      2013-03-22 10:22:12.721324      stopping JOB='avahi-cups-reload' INSTANCE='' RESULT='ok'
12      2013-03-22 10:22:12.721686      stopped JOB='avahi-cups-reload' INSTANCE='' RESULT='ok'
13      2013-03-22 10:22:12.721892      started JOB='avahi-daemon' INSTANCE=''

And this is stop avahi and start avahi:
1       2013-03-22 10:22:12.696810      stopping JOB='avahi-daemon' INSTANCE='' RESULT='ok'
2       2013-03-22 10:22:12.704692      stopping JOB='cups-browsed' INSTANCE='' RESULT='ok'
3       2013-03-22 10:22:12.705150      starting JOB='cups-browsed' INSTANCE=''
4       2013-03-22 10:22:12.705537      started JOB='cups-browsed' INSTANCE=''
5       2013-03-22 10:22:12.705920      starting JOB='avahi-daemon' INSTANCE=''
6       2013-03-22 10:22:12.706322      stopping JOB='cups-browsed' INSTANCE='' RESULT='ok'
7       2013-03-22 10:22:12.706703      starting JOB='cups-browsed' INSTANCE=''
8       2013-03-22 10:22:12.712707      started JOB='cups-browsed' INSTANCE=''
9       2013-03-22 10:22:12.720260      starting JOB='avahi-cups-reload' INSTANCE=''
10      2013-03-22 10:22:12.720981      started JOB='avahi-cups-reload' INSTANCE=''
11      2013-03-22 10:22:12.721324      stopping JOB='avahi-cups-reload' INSTANCE='' RESULT='ok'
12      2013-03-22 10:22:12.721686      stopped JOB='avahi-cups-reload' INSTANCE='' RESULT='ok'
13      2013-03-22 10:22:12.721892      started JOB='avahi-daemon' INSTANCE=''

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https://bugs.launchpad.net/bugs/1158686

Title:
  When restarting avahi-daemon cups does not reconnect to it -
  workaround

Status in “avahi” package in Ubuntu:
  New

Bug description:
  I use CUPS with shared printers and the shared printers are Bonjour-
  broadcasted by Avahi. This works well when avahi-daemon is started
  before cups and both keep running. But if I restart (stop and start
  gain) avahi-daemon while CUPS is running, CUPS does not reconnect to
  avahi-daemon again and so stops broadcasting. What I expect is that
  CUPS reconnects after the restart of avahi-daemon. This can easily
  happen if for example the avahi-daemon package gets updated, avahi-
  daemon crashes, or the admin changes the configuration of avahi-
  daemon.

  I am using Ubuntu Raring (13.04) with CUPS 1.6.2.

  The real fix would need to be done in CUPS and therefore I did the
  following upstream bug report:

  https://www.cups.org/str.php?L4300

  For the time being until CUPS gets fixed I suggest the following
  workaround:

  If one adds the following lines to the end of the /etc/init/avahi-
  daemon.conf file

  ----------
  post-start script
      if lpstat -h localhost -r 2>/dev/null | grep -qv not; then
          killall -HUP cupsd
      fi
  end script
  ----------

  the CUPS daemon gets kicked after starting avahi-daemon and so
  reconnects. The "if" only comes true if "lpstat" is present and the
  answer of "lpstat -h localhost -r" does not contain "not", meaning
  that the CUPS daemon is running.

  This works at least for restarting the avahi-daemon by "stop avahi-
  daemon; ...; start avahi-daemon" (what happens when updating avahi-
  daemon) or by the "respawn" (what happens when avahi-daemon crashes).

  It does not work with "restart avahi-daemon". Any addition to my
  suggested workaround to make this work is welcome.

  Can this workaround be applied to Raring? Thanks.

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