If distribution is Debian/Ubuntu

gistfile1.php

<?php
// Simple socket server
// See http://php.net/manual/en/function.stream-socket-server.php
$port = $argv[1];
$mysql_port = $argv[2];
$mysql = "/usr/bin/mysql";
$query = "SHOW SLAVE STATUS";
function set_weight($lag){
	# Write your own rules here
	if ($lag == 'NULL'){
		return "down";
	}
	else if ($lag < 10){
		return "up 100%";
	}
	else if ($lag -->= 10 && $lag < 60){
		return "up 50%";
	}
	else
		return "up 5%";
}
set_time_limit(0);
$socket = stream_socket_server("tcp://0.0.0.0:$port", $errno, $errstr);
if (!$socket) {
	echo "$errstr ($errno)
n";
} else {
	while ($conn = stream_socket_accept($socket,9999999999999)) {
		$cmd = "$mysql -h127.0.0.1 --defaults-file=/etc/mysql/debian.cnf -Ee \"$query\" | grep Seconds_Behind_Master | cut -d ':' -f2 | tr -d ' '";
		exec("$cmd",$lag);
		$weight = set_weight($lag[0]);
		unset($lag);
		fputs ($conn, $weight);
		fclose ($conn);
	}
	fclose($socket);
}
?>