MooseX::Daemonize and init.d

It only took me two weeks in the Iron Man competition to fail. That may actually be some kind of record. The last few weeks at $work have been pretty busy and I haven’t had the time or energy to work on blog posts. However, with YAPC::NA only a few days away and my excitement growing I decided to write up a quick post with a bit of fun I had messing with daemons.

In the past I’ve written my daemons as simple scripts. They worked reasonably well but after a couple years and even more rewrites I decided to see what CPAN had to offer. In particular I thought I’d take a look at a more moosey implementation. Turns out it’s super easy and includes all the things I needed to run it as a system service.

package MyDaemon;
use Moose;
use Try::Tiny;
use namespace::autoclean;

with qw(MooseX::Daemonize);

after start => sub {
	my $self = shift;
	return unless $self->is_daemon();
	
	while (1) {
			try {
				# Your daemon code here
			}
		}
		
		sleep(3600);
	}
};

That’s it. The MooseX::Daemonize code handles pretty much everything you’d expect a daemon to do. Next, I wanted it to be integrated as a system service. For that I had to make it runnable using MooseX::Runnable.

package MyDaemon;
use Moose;
use Try::Tiny;
use namespace::autoclean;

with qw(MooseX::Daemonize MooseX::Runnable);

sub run {
	my $self = shift;
	
	$self->start();
	
	exit(0);
}

after start => sub {
	my $self = shift;
	return unless $self->is_daemon();
	
	while (1) {
			try {
				# Your daemon code here
			}
		}
		
		sleep(3600);
	}
};

Ok, simple enough. Now the module can be run as an application using the mx-run command. On to the final step, the init.d script.

PIDFILE=/var/run/mydaemon.pid
COMMAND="mx-run -I/path/to/MyDaemon.pm"

# Source function library
. /etc/rc.d/init.d/functions


start() {
        echo -n "Starting My Daemon: "
        if [ -f $PIDFILE ]; then
                PID=`cat $PIDFILE`
                echo my daemon already running: $PID
                exit 2;
	fi

        daemon $COMMAND
	echo
}

stop() {
        echo -n "Stopping My Daemon: "

        killproc mydaemon
	echo
}

case "$1" in
  start)
	start
        ;;
  stop)
	stop
        ;;
  restart)
        stop
	start
        ;;
  status)
        status mydaemon
        ;;
  *)
        echo "Usage: {start|stop|restart|status}"
        exit 1
esac

exit 0

Now I can do service mydaemon start/stop/status/restart and the system manages the daemon for me. A simple chkconfig and it’s running at startup. Very nice.

Please be aware that I’m running CentOS 5.4 so your mileage may vary in regards to the init.d script.