#!/usr/bin/perl
#
# Copyright (C) 2008 Rackspace US, Inc. <http://www.rackspace.com>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2 dated June,
# 1991.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, see http://www.gnu.org/licenses/gpl.txt
#
#
# This plugin is based off of the Connection Usage
# section of the MySQL Connection Health Page
#
# http://dev.mysql.com/doc/administrator/en/mysql-administrator-health-connection-health.html
#
# To enable, link mysql_connections to this file. E.g.
#
#    ln -s /usr/share/node/node/plugins/mysql_connections /etc/munin/plugins/mysql_connections
#
# Revision 1.0  2007/08/03
# Created by Justin Shepherd <galstrom21@gmail.com>
#
# Parameters:
#
#   config
#   autoconf
#
# Configuration variables
#
#   mysqlopts     - Options to pass to mysql
#   mysqladmin    - Override location of mysqladmin
#   warning	  - Override default warning limit
#   critical	  - Override default critical limit
#
#%# family=auto
#%# capabilities=autoconf

use strict;

# Define the mysqladmin paths, and commands
my $MYSQLADMIN = $ENV{mysqladmin} || "mysqladmin";
my $TEST_COMMAND    = "$MYSQLADMIN $ENV{mysqlopts} extended-status";
my $MYSQL_VARIABLES = "$MYSQLADMIN $ENV{mysqlopts} extended-status variables";
my $warning = $ENV{warning} || "80";
my $critical = $ENV{critical} || "90";

# Pull in any arguments
my $arg = shift();

# Check to see how the script was called
if ($arg eq 'config') {
    print_graph_information();
    exit();
} elsif ($arg eq 'autoconf') {
    if (test_service()) { print "yes\n"; }
    else { print "no\n"; }
    exit;
} else {
	# Define the values that are returned to munin
	my ($available, $current, $upper_limit) = (0,0,0);

	# Gather the values from mysqladmin
	$current = poll_variables($MYSQL_VARIABLES,"Threads_connected");
	$upper_limit = poll_variables($MYSQL_VARIABLES,"max_connections");
	$available = $upper_limit - $current;

	# Return the values to Munin
	print "current.value $current\n";
	print "available.value $available\n";
}


sub poll_variables {
	my $command = shift;
	my $expression = shift;
	my $ret = 0;
	open(SERVICE, "$command |")
		or die("Could not execute '$command': $!");
	while (<SERVICE>) {
            my ($field, $value) = (m/(\w+).*?(\d+(?:\.\d+)?)/);
	    next unless ($field);
	    if ($field eq $expression ) {
		$ret = "$value";
	    }
	}
	close(SERVICE);
	return $ret;
}


sub print_graph_information {
print <<EOM;
graph_title MySQL Connections
graph_args --base 1000 --lower-limit 0
graph_vlabel Connections
graph_info The number of current connections with respect to the max_connections setting.
graph_category db
graph_order current available
graph_total Total
current.label In Use
current.draw AREA
current.info The number of current threads connected
current.warning $warning
current.critical $critical
available.label Available
available.draw STACK
available.info The current value of the "max_connections" variable
EOM
}


sub test_service {
    my $return = 1;
    system ("$MYSQLADMIN --version >/dev/null 2>/dev/null");
    if ($? == 0)
    {
		system ("$TEST_COMMAND >/dev/null 2>/dev/null");
		if ($? == 0)
		{
		    print "yes\n";
		    $return = 0;
		}
		else
		{
	   		print "no (could not connect to mysql)\n";
		}
    }
    else
    {
		print "no (mysqladmin not found)\n";
    }
    exit $return;
}