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  1. ZABBIX BUGS AND ISSUES
  2. ZBX-19709

kill(1) in systemd service files produces confusing error messages in log if the service failed to start

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Details

    • Problem report
    • Status: Closed
    • Trivial
    • Resolution: Fixed
    • 5.4.2
    • 5.4.6rc1, 6.0.0alpha4, 6.0 (plan)
    • Packages (C)
    • None
    • Debian GNU/Linux version 9 (Stretch), with systemd(1) as init system.
    • Team B
    • Sprint 78 (Jul 2021), Sprint 79 (Aug 2021), Sprint 80 (Sep 2021)
    • 0.5

    Description

      Currently the systemd service configuration files installed by Zabbix Debian packages contain the following line:

      ExecStop=/bin/kill -SIGTERM $MAINPID
      

      It works fine in most cases; but if the specified service has failed to start, for example, failed to bind(2) to its listing port, systemd(1) will invoke the ExecStop command line with $MAINPID expanded to empty, before trying to restart the service; the caused kill(1) to produce a long usage message in log, becasue no PID is specified; take service zabbix-agent for example, the log would be like:

      Jul 15 12:56:23 x systemd[1]: Starting Zabbix Agent...
      Jul 15 12:56:23 x systemd[1]: zabbix-agent.service: Supervising process 69594 which is not our child. We'll most likely not notice when it exits.
      Jul 15 12:56:23 x systemd[1]: Started Zabbix Agent.
      Jul 15 12:56:23 x systemd[1]: zabbix-agent.service: Main process exited, code=exited, status=1/FAILURE
      Jul 15 12:56:23 x kill[69598]: Usage:
      Jul 15 12:56:23 x kill[69598]:  kill [options] <pid> [...]
      Jul 15 12:56:23 x kill[69598]: Options:
      Jul 15 12:56:23 x kill[69598]:  <pid> [...]            send signal to every <pid> listed
      Jul 15 12:56:23 x kill[69598]:  -<signal>, -s, --signal <signal>
      Jul 15 12:56:23 x kill[69598]:                         specify the <signal> to be sent
      Jul 15 12:56:23 x kill[69598]:  -l, --list=[<signal>]  list all signal names, or convert one to a name
      Jul 15 12:56:23 x kill[69598]:  -L, --table            list all signal names in a nice table
      Jul 15 12:56:23 x kill[69598]:  -h, --help     display this help and exit
      Jul 15 12:56:23 x kill[69598]:  -V, --version  output version information and exit
      Jul 15 12:56:23 x kill[69598]: For more details see kill(1).
      Jul 15 12:56:23 x systemd[1]: zabbix-agent.service: Control process exited, code=exited status=1
      Jul 15 12:56:23 x systemd[1]: zabbix-agent.service: Unit entered failed state.
      Jul 15 12:56:23 x systemd[1]: zabbix-agent.service: Failed with result 'exit-code'.
      

      These log messages will repeating every time the service process failed.
       
      I suggest changing the ExecStop command line as followings, to avoid produce such confusing messages in log:

      ExecStop=/bin/sh -c '[ -n "$1" ] && kill -s TERM "$1"' -- "$MAINPID"
      

      In addition, the kill(1) command usage has changed silently for POSIX compliance; specifically, according to this page:

      Values of signal_name shall be recognized in a case-independent fashion, without the SIG prefix.
      

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            yurii Jurijs Klopovskis
            Low-power WHR
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              Created:
              Updated:
              Resolved: