About

This is a simple watchdog application designed to periodically check the presence of some daemons and start them if necessary. It has proven very useful for monitoring complex C programs (e.g., SER, rtpproxy) that may terminate unexpectedly due to code bugs.

Usage

The usage is straightforward - sipwd should be started periodically (for example, every minute by cron(8)) for each program to be monitored. All necessary arguments are passed via the command line. The synopsis is as follows:

sipwd <runfile> <binfile> <pidfile> <command> [<force_restart_file>]

• <runfile>: Name of the file indicating that the service has been started. If it doesn't exist, the watchdog exits.
• <binfile>: Name of the binary for the service to be checked. For interpreted languages like Python or Perl, this should be the interpreter's name.
• <pidfile>: Name of the file containing one or more PIDs for the service. The watchdog verifies that all PIDs match the running processes.
• <command>: Command to start the service if it's not running.
• <force_restart_file>: Optional. Used to forcibly restart the monitored application if it starts working improperly.

For example, to monitor the rtpproxy service:

sipwd /var/run/rtpproxy.runs /usr/local/bin/rtpproxy \
/var/run/rtpproxy.pid "/usr/local/etc/rc.d/rtpproxy.sh start"

The watchdog uses the siplog library for logging. The SIPLOG_BEND and SIPLOG_LOGFILE_FILE environment variables can be set to modify its behavior.

Integration

1. Install sipwd.

2. Ensure procfs is mounted and enabled in /etc/fstab.

3. Modify the startup scripts of services to be monitored to create/remove <runfile> on start/stop. Example:

   case "$1" in
   start)
     /usr/local/bin/rtpproxy -l 1.2.3.4 -p /var/run/rtpproxy.pid
     touch /var/run/rtpproxy.runs
     ;;
   stop)
     rm -f /var/run/rtpproxy.runs
     /bin/kill -TERM `/bin/cat /var/run/rtpproxy.pid 2>/dev/null` 2>/dev/null
     ;;
   esac

4. Add the appropriate crontab(5) entry. If the machine has multiple services to be monitored, it's practical to create a shell script and put multiple invocations of sipwd into it, then invoke that script from cron(8).