[Bug 1481737] Re: HAProxy init script does not work correctly with nbproc configuration option

[Louis Bouchard]

** Patch removed: "lp1494141_fix_stop_failure.debdiff"
   https://bugs.launchpad.net/ubuntu/+source/haproxy/+bug/1481737/+attachment/4473139/+files/lp1494141_fix_stop_failure.debdiff

** Patch added: "lp1481737_stop_multipid.debdiff"
   https://bugs.launchpad.net/ubuntu/+source/haproxy/+bug/1481737/+attachment/4492590/+files/lp1481737_stop_multipid.debdiff

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https://bugs.launchpad.net/bugs/1481737

Title:
  HAProxy init script does not work correctly with nbproc configuration
  option

Status in haproxy package in Ubuntu:
  Invalid
Status in haproxy source package in Trusty:
  In Progress

Bug description:
  [SRU justification]
  The sysVinit script does not completely stop processes when nbproc > 1

  [Impact]
  Stopping haproxy without this fix leaves all but one process running

  [Fix]
  Use temporary pidfile in a loop containing one single PID as the --pid option is not available for start-stop-daemon.

  [Test Case]
  Set nbproc > 4 in /etc/haproxy/haproxy.cfg
  resart haproxy & verify that there is more than one haproxy process
  Run :
  $ ps aux | grep haproxy | grep -v grep | wc -l
  4
  $ service haproxy stop
  $ ps aux | grep haproxy | grep -v grep | wc -l

  Without the patch, the result of the last command will be 3. With the
  fix, it will be 0

  [Regression]
  The regression risk is in the use of a temporary file instead of the start-stop-daemon option.

  It has been tested with TMPDIR="/tmp/My Dir" to check for spaces in
  directory names.

  [Original description of the problem]
  In case you have more than one process enabled in the haproxy config, the init script fails to stop all of those processes.
  So to clarify you need to have this in your haproxy.cfg:

  """
  ...
  global
          maxconn         32000
          ulimit-n        65536
          user            haproxy
          group           haproxy
          nbproc          2

  ...
  """

  the problem is more visible if you set the nbproc to higher number.

  service haproxy stop --> will only stop on of the haproxy processes.

  The problem is so that start-stop-daemon can't handle pid files with multiple lines. Only stopping the first one. HAProxy does write all the pids started by itself into the pid file, so the problem is not in HAProxy, but in the start-stop-daemon or more likely in the init scrip of haproxy.
  One solution or workaround is to remove pidfile option of start-stop-daemon in the init script, than it wil work as killall and will stop the haproxy processes properly.

  To proof you can try this sequence:

  service haproxy start #if its not running
  ps ax | grep haproxy | grep -v grep | wc -l #this should report 2
  service haproxy restart
  ps ax | grep haproxy | grep -v grep | wc -l #this will report 3

  The workaround as a diff:
  root at ubi1:/opt# diff /etc/init.d/haproxy /etc/init.d/haproxy.orig
  62c62
  <               --retry 5 --exec $HAPROXY || ret=$?
  ---
  >               --retry 5 --pidfile $PIDFILE --exec $HAPROXY || ret=$?

  extra infos:
  root at ubi1:/opt# lsb_release -rd
  Description:    Ubuntu 14.04.3 LTS
  Release:        14.04

  root at ubi1:/opt# apt-cache policy haproxy
  haproxy:
    Installed: 1.4.24-2ubuntu0.2
    Candidate: 1.4.24-2ubuntu0.2
    Version table:
       1.5.3-1~ubuntu14.04.1 0
          100 http://us.archive.ubuntu.com/ubuntu/ trusty-backports/main amd64 Packages
   *** 1.4.24-2ubuntu0.2 0
          500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       1.4.24-2 0
          500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

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