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[ChristianEhrhardt <1644530@xxxxxxxxxxxxxxxxxx>]

> Anything else needed on src:systemd side of things?

Hi xnox,
Well, in a perfect world and with a time machine to help you could look what in zesty's systemd fixed it to work reliably even with the suboptimal service file.
But then you have more important tasks all around you and it is fixed where it was broken. Until then I think "opinion" is more appropriate than "incomplete" - yet at whatever state it is ok to just let it hang around for now.

If similar issues come up for other services we might reconsider.

** Changed in: systemd (Ubuntu)
       Status: Incomplete => Opinion

** Changed in: systemd (Ubuntu Xenial)
       Status: Incomplete => Opinion

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https://bugs.launchpad.net/bugs/1644530

Title:
  keepalived fails to restart cleanly due to the wrong systemd settings

Status in keepalived package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Opinion
Status in keepalived source package in Xenial:
  Fix Released
Status in systemd source package in Xenial:
  Opinion
Status in keepalived package in Debian:
  New

Bug description:
  [Impact]

   * Restarts of keepalived can leave stale processes with the old
  configuration around.

   * The systemd detection of the MainPID is suboptimal, and combined
  with not waiting on signals being handled it can fail on second
  restart killing the (still) remaining process of the first start.

   * Upstream has a PIDFile statement, this has proven to avoid the
  issue in the MainPID guessing code of systemd.

  [Test Case]

   * Set up keepalived, the more complex the config is the "bigger" is the reace window, below in the description is a trivial sample config that works well.
   
   * As a test run the loop restarting the service head-to-head while staying under the max-restart limit
  $ for j in $(seq 1 20); do sleep 11s; time for i in $(seq 1 5); do sudo systemctl restart keepalived; sudo systemctl status keepalived | egrep 'Main.*exited'; done; done

   Expectation: no output other than timing
   Without fix: sometimes MainPIDs do no more exist, in these cases the child processes are the "old" ones from last execution with the old config.

  [Regression Potential]

   * Low because
     * A PIDFile statement is recommended by systemd for type=forking services anyway.
     * Upstream keepalived has this statement in their service file
     * By the kind of change, it should have no functional impact to other parts of the service other than for the PID detection of the job by Systemd.

   * Yet regression potential is never zero. There might be the unlikely
  case, which were considered working before due to a new config not
  properly being picked up. After the fix they will behave correctly and
  might show up as false-positives then if e.g. config was bad.

  [Other Info]
   
   * Usually a fix has to be in at least the latest Development release before SRUing it. But as I outlined below in later Releases than Xenial systemd seems to have improved making this change not-required. We haven't identified the bits for this (there is a bug task here), and they might as well be very complex. I think it is correct to fix Xenial in this regard with the simple change to the service file for now.

   * To eventually match I created a Debian bug task to ask them for the
  inclusion of the PIDFile so it can slowly tickle back down to newer
  Ubuntu Releases - also there more often people run backports where the
  issue might occur on older systemd versions (just as it does for us on
  Xenial)

  ---

  Because "PIDFile=" directive is missing in the systemd unit file,
  keepalived sometimes fails to kill all old processes. The old
  processes remain with old settings and cause unexpected behaviors. The
  detail of this bug is described in this ticket in upstream:
  https://github.com/acassen/keepalived/issues/443.

  The official systemd unit file is available since version 1.2.24 by
  this commit:

  https://github.com/acassen/keepalived/commit/635ab69afb44cd8573663e62f292c6bb84b44f15

  This includes "PIDFile" directive correctly:

  PIDFile=/var/run/keepalived.pid

  We should go the same way.

  I am using Ubuntu 16.04.1, kernel 4.4.0-45-generic.

  Package: keepalived
  Version: 1.2.19-1

  =======================================================================

  How to reproduce:

  I used the two instances of Ubuntu 16.04.2 on DigitalOcean:

  Configurations
  --------------

  MASTER server's /etc/keepalived/keepalived.conf:

    vrrp_script chk_nothing {
       script "/bin/true"
       interval 2
    }

    vrrp_instance G1 {
      interface eth1
      state BACKUP
      priority 100

      virtual_router_id 123
      unicast_src_ip <primal IP>
      unicast_peer {
        <secondal IP>
      }
      track_script {
        chk_nothing
      }
    }

  BACKUP server's /etc/keepalived/keepalived.conf:

    vrrp_script chk_nothing {
       script "/bin/true"
       interval 2
    }

    vrrp_instance G1 {
      interface eth1
      state MASTER
      priority 200

      virtual_router_id 123
      unicast_src_ip <secondal IP>
      unicast_peer {
        <primal IP>
      }
      track_script {
        chk_nothing
      }
    }

  Loop based probing for the Error to exist:
  ------------------------------------------
  After the setup above start keepalived on both servers:
      $ sudo systemctl start keepalived.service
  Then run the following loop
      $ for j in $(seq 1 20); do sleep 11s; time for i in $(seq 1 5); do sudo systemctl restart keepalived; sudo systemctl status keepalived | egrep 'Main.*exited'; done; done

  Expected: no error, only time reports
  Error case: Showing Main PID exited, details below

  Step by Step Procedures
  -----------------------

  1) Start keepalived on both servers

    $ sudo systemctl start keepalived.service

  2) Restart keepalived on either one

    $ sudo systemctl restart keepalived.service

  3) Check status and PID

    $ systemctl status -n0 keepalived.service

  Result
  ------

  0) Before restart

  Main PID is 3402 and the subprocesses' PIDs are 3403-3406. So far so
  good.

    root@ubuntu-2gb-sgp1-01:~# systemctl status -n0 keepalived
    ● keepalived.service - Keepalive Daemon (LVS and VRRP)
       Loaded: loaded (/lib/systemd/system/keepalived.service; enabled; vendor preset: enabled)
       Active: active (running) since Sat 2017-03-04 01:37:12 UTC; 14min ago
      Process: 3402 ExecStart=/usr/sbin/keepalived $DAEMON_ARGS (code=exited, status=0/SUCCESS)
     Main PID: 3403 (keepalived)
        Tasks: 3
       Memory: 1.7M
          CPU: 1.900s
       CGroup: /system.slice/keepalived.service
               ├─3403 /usr/sbin/keepalived
               ├─3405 /usr/sbin/keepalived
               └─3406 /usr/sbin/keepalived

  1) First restart

  Now Main PID is 3403, which was one of the previous subprocesses and
  is actually exited. Something is wrong. Yet, the previous processes
  are all exited; we are not likely to see no weird behaviors here.

    root@ubuntu-2gb-sgp1-01:~# systemctl restart keepalived
    root@ubuntu-2gb-sgp1-01:~# systemctl status -n0 keepalived
    ● keepalived.service - Keepalive Daemon (LVS and VRRP)
       Loaded: loaded (/lib/systemd/system/keepalived.service; enabled; vendor preset: enabled)
       Active: active (running) since Sat 2017-03-04 01:51:45 UTC; 1s ago
      Process: 4782 ExecStart=/usr/sbin/keepalived $DAEMON_ARGS (code=exited, status=0/SUCCESS)
     Main PID: 3403 (code=exited, status=0/SUCCESS)
        Tasks: 3
       Memory: 1.7M
          CPU: 11ms
       CGroup: /system.slice/keepalived.service
               ├─4783 /usr/sbin/keepalived
               ├─4784 /usr/sbin/keepalived
               └─4785 /usr/sbin/keepalived

  2) Second restart

  Now Main PID is 4783 and subprocesses' PIDs are 4783-4785. This is
  problematic as 4783 is the old process, which should have exited
  before new processes arose. Therefore, keepalived remains in old
  settings while users believe it uses the new setting.

    root@ubuntu-2gb-sgp1-01:~# systemctl restart keepalived
    root@ubuntu-2gb-sgp1-01:~# systemctl status -n0 keepalived
    ● keepalived.service - Keepalive Daemon (LVS and VRRP)
       Loaded: loaded (/lib/systemd/system/keepalived.service; enabled; vendor preset: enabled)
       Active: active (running) since Sat 2017-03-04 01:51:49 UTC; 1s ago
      Process: 4796 ExecStart=/usr/sbin/keepalived $DAEMON_ARGS (code=exited, status=0/SUCCESS)
     Main PID: 4783 (keepalived)
        Tasks: 3
       Memory: 1.7M
          CPU: 6ms
       CGroup: /system.slice/keepalived.service
               ├─4783 /usr/sbin/keepalived
               ├─4784 /usr/sbin/keepalived
               └─4785 /usr/sbin/keepalived

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