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  1. VCL
  2. VCL-1027

External SSH service under systemd fails to restart if several restarts are rapidly attempted



    • Type: Improvement
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 2.5
    • Component/s: None
    • Labels:


      I have seen this occur on server requests when multiple users are added in a short amount of time. The ext_sshd service is restarted every time a user is added. There is some threshold in systemd that prevents this, causing the service to stop and not restart without waiting for a few seconds.

      This is the error:

      [root@bn17-97 ~]# service ext_sshd restart
      Redirecting to /bin/systemctl restart  ext_sshd.service
      [root@bn17-97 ~]# service ext_sshd restart
      Redirecting to /bin/systemctl restart  ext_sshd.service
      [root@bn17-97 ~]# service ext_sshd restart
      Redirecting to /bin/systemctl restart  ext_sshd.service
      [root@bn17-97 ~]# service ext_sshd restart
      Redirecting to /bin/systemctl restart  ext_sshd.service
      [root@bn17-97 ~]# service ext_sshd restart
      Redirecting to /bin/systemctl restart  ext_sshd.service
      Job for ext_sshd.service failed because start of the service was attempted too often. See "systemctl status ext_sshd.service" and "journalctl -xe" for details.
      To force a start use "systemctl reset-failed ext_sshd.service" followed by "systemctl start ext_sshd.service" again.

      When this occurs, users can't connect to the reservation. There is currently no code that detects or corrects this.

      Options could be added to the systemd service file created in systemd.pm::add_ext_sshd_service.

      From the systemd.service man page:

      StartLimitInterval=, StartLimitBurst=
      Configure service start rate limiting. By default, services which are started more than 5 times within 10 seconds are not permitted to start any more times until the 10 second interval ends. With these two options, this rate limiting may
      be modified. Use StartLimitInterval= to configure the checking interval (defaults to DefaultStartLimitInterval= in manager configuration file, set to 0 to disable any kind of rate limiting). Use StartLimitBurst= to configure how many
      starts per interval are allowed (defaults to DefaultStartLimitBurst= in manager configuration file). These configuration options are particularly useful in conjunction with Restart=; however, they apply to all kinds of starts (including
      manual), not just those triggered by the Restart= logic. Note that units which are configured for Restart= and which reach the start limit are not attempted to be restarted anymore; however, they may still be restarted manually at a later
      point, from which point on, the restart logic is again activated. Note that systemctl reset-failed will cause the restart rate counter for a service to be flushed, which is useful if the administrator wants to manually start a service and
      the start limit interferes with that.

      Configure the action to take if the rate limit configured with StartLimitInterval= and StartLimitBurst= is hit. Takes one of none, reboot, reboot-force, reboot-immediate, poweroff, poweroff-force or poweroff-immediate. If none is set,
      hitting the rate limit will trigger no action besides that the start will not be permitted. reboot causes a reboot following the normal shutdown procedure (i.e. equivalent to systemctl reboot). reboot-force causes a forced reboot which
      will terminate all processes forcibly but should cause no dirty file systems on reboot (i.e. equivalent to systemctl reboot -f) and reboot-immediate causes immediate execution of the reboot(2) system call, which might result in data loss.
      Similar, poweroff, poweroff-force, poweroff-immediate have the effect of powering down the system with similar semantics. Defaults to none.


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              • Assignee:
                arkurth Andrew Kurth
                arkurth Andrew Kurth
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