Running a failure script

Purpose:

You can create a failure script that is executed when AxoSyslog terminates abnormally, that is, when it exits with a non-zero exit code. For example, you can use this script to send an automatic email notification.

Prerequisites:

The failure script must be the following file: /opt/syslog-ng/sbin/syslog-ng-failure, and must be executable.

To create a sample failure script, complete the following steps.

Steps:

1. Create a file named /opt/syslog-ng/sbin/syslog-ng-failure with the following content:

       #!/usr/bin/env bash
       cat >>/tmp/test.txt <<EOF
       $(date)
       Name............$1
       Chroot dir......$2
       Pid file dir....$3
       Pid file........$4
       Cwd.............$5
       Caps............$6
       Reason..........$7
       Argbuf..........$8
       Restarting......$9
   
       EOF
   

2. Make the file executable: chmod +x /opt/syslog-ng/sbin/syslog-ng-failure

3. Run the following command in the /opt/syslog-ng/sbin directory: ./syslog-ng --process-mode=safe-background; sleep 0.5; ps aux | grep './syslog-ng' | grep -v grep | awk '{print $2}' | xargs kill -KILL; sleep 0.5; cat /tmp/test.txt

   The command starts AxoSyslog in safe-background mode (which is needed to use the failure script) and then kills it. You should see that the relevant information is written into the /tmp/test.txt file, for example:

       Thu May 18 12:08:58 UTC 2017
       Name............syslog-ng
       Chroot dir......NULL
       Pid file dir....NULL
       Pid file........NULL
       Cwd.............NULL
       Caps............NULL
       Reason..........signalled
       Argbuf..........9
       Restarting......not-restarting
   

4. You should also see messages similar to the following in system syslog. The exact message depends on the signal (or the reason why AxoSyslog stopped):

       May 18 13:56:09 myhost supervise/syslog-ng[10820]: Daemon exited gracefully, not restarting; exitcode='0'
       May 18 13:57:01 myhost supervise/syslog-ng[10996]: Daemon exited due to a deadlock/signal/failure, restarting; exitcode='131'
       May 18 13:57:37 myhost supervise/syslog-ng[11480]: Daemon was killed, not restarting; exitcode='9'
   

   The failure script should run on every non-zero exit event.