#!/usr/bin/perl -w
# productname: loadwatch
# productrelease: V0.1
#
# copyright 2005 by kapper.net
# reach kapper.net at http://kapper.net/ or via postal mail to:
# kapper & partner communications keg, kapper.net gmbh
#  loeblichgasse 6, A-1090 Vienna, Austria
# development-team: mm@kapper.net, hk@kapper.net
#
# 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; either version 2 of the License, or (at your option)
# any later version.
#
# 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, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
# http://www.gnu.org/licenses/gpl.txt

# ----------------------------------------------------
# project started: 15.02.2005
# ----------------------------------------------------
# synopsis:
# script checks the /proc/loadavg for the systemload and if that is critical
# sends an email to notify its master and writes to syslog that the problem
# arose.
#
# requirements: Mail::Sendmail perl-class (available from http://alma.ch/perl/mail.html or CPAN)
#               local sendmail/postfix/whatever mailserver to deliver the sent email if required
#		alternatively you can edit Sendmail.pm to have your smtp-server globally set
#
# currently hardcoded: loadavg of >5 for 15 minutes and >8 for 5 minutes and >10 for 1 minute is
#                      classified as critical load
#
# usage: loadwatch <params>
# 
# possible parameters
# -------------------
# 
#         --check-load | -c
#           reads output of "/proc/loadavg"
#           if there is a problem write to syslog and optional send email
#           --sendto <emailaddress> | -s
#             this is an optional parameter, if used, it requires an email address,
#             to which a possible problem-report is sent.
#
#
#
# History:
# --------
# 15.02.2005	hk	adopt from httpdcheck perl-code
#


use strict;
use Fcntl;				# for file io
use Mail::Sendmail;			# for sendmail class
use Sys::Syslog;			# for notification of syslog-services


my $LAVG = "/proc/loadavg";		# file that contains loadavg interface
# if needed please change the above systemcall and filepath/-name.
# possible params
my $PARAM_CHECK = "--check-load";
my $PARAM_SEND  = "--sendto";
my $PARAM_CHECK_SHORT = "-c";
my $PARAM_SEND_SHORT  = "-s";
# constants
my $PDEFAULT =  0b0000;
my $callparam = $PDEFAULT;	# don't ask ;-)
my $READ   = 0b1000;
my $CHECK  = 0b0100;
my $SEND   = 0b0010;
my $EQUAL  = 123443;	# here it means "loadavg is ok"
my $NOTEQUAL = 394342;	# here it means do a problem-report and restart
#my $FROM    = "";	# set to get a specific from-address
my $SUBJECT = "load average critcal: " . `hostname`;

# --------------------------------------------
# compares the submitted strings on the loadavg
# above specified constants for EQUAL and NOTEQUAL get returned.
# parameters are oneminute fiveminutes fifteenminutes
sub compare
{
	my $mone = $_[0];
	my $mfive = $_[1];
	my $mfifteen = $_[2];
	my $rc = $NOTEQUAL; 
	my ($one, $five, $fifteen);
	# - - - - - - - -

	open(LOAD,$LAVG) ||
		return $NOTEQUAL; # meaning: "4564 Cannot read load average: $!"
	my $line = <LOAD>;
	$line =~ /^(\d+\.\d+)\s*(\d+\.\d+)\s*(\d+\.\d+)/o;
	close LOAD;

	$one = $1;
	$five = $2;
	$fifteen = $3;

	if ($one >= $mone)
	{
		$rc = $NOTEQUAL;
	}
	elsif ($five >= $mfive)
	{
		$rc = $NOTEQUAL;
	}
	elsif ($fifteen >= $mfifteen)
	{
		$rc = $NOTEQUAL;
	}
	else
	{
		$rc = $EQUAL; 	# all tests are fine it seems
	}

	return ($rc);
}	
# --------------------------------------------------------------------------
# give the user some hints on how to use...
sub usage
{
	my $usageinfo = "";
	
	$usageinfo .= "---------------------------------------------------------\n";
	$usageinfo .= "usage: $0 <params>\n\n";
	$usageinfo .= "possible parameters\n";
	$usageinfo .= "-------------------\n";	
	$usageinfo .= "\t--check-load | -c\n";
	$usageinfo .= "\t  checks for a decent loadavg and escalates if necessary\n";
	$usageinfo .= "\t  if there is a problem it reports to STDOUT\n";
	$usageinfo .= "\t  --sendto <emailaddress> | -s <email>\n";
	$usageinfo .= "\t    this is optional - if used - it requires an email address,\n";
	$usageinfo .= "\t    a possible problem is mailed to the given address.\n";
	$usageinfo .= "Have fun and may your server never overload ;)\n";
	$usageinfo .= "copyright 2005 by http://kapper.net/\n\n";
	$usageinfo .= "---------------------------------------------------------\n";

	die "$usageinfo";
}
# ----------------------------------------
# main

{
	my $param = shift @ARGV;	# shift gets the next parameter and cuts it off ARGV
	my $infotxt = "";
	my $program = "loadwatch";
	my ($mailadr,$cmdreply,$rc,$rc1);
	my %mail;	# sendmail needs this


	while (defined $param)		# as long as there are parameters
	{
		if (($param eq $PARAM_CHECK) || ($param eq $PARAM_CHECK_SHORT))
		{
			$callparam |= $CHECK;
		}
		elsif (($param eq $PARAM_SEND) || ($param eq $PARAM_SEND_SHORT))
		{
			$callparam |= $SEND;
			$mailadr = shift @ARGV;				# next parameter needs to be an email address
			if (!($mailadr))
			{
				$callparam = $PDEFAULT; 		# default value ... means error and needs to show usage
			}
			else
			{
				if (!($mailadr =~m/.+\@.+\..+/))
				{
					$callparam = $PDEFAULT;		# default value ... means error and needs to show usage
				}
			}
		}
		else  						# no params
		{
			$callparam = $PDEFAULT; # default value ... means error and needs to show usage
		}		
		
		$param = shift @ARGV;	# get next parameter
	}	
		
	if ($callparam == ($SEND))         { $callparam = $PDEFAULT;}  # no sendonly option
	
	&usage if ($callparam == $PDEFAULT);

	if (($callparam & $CHECK) == $CHECK)
	{
		$rc = compare(10,8,5);	# loadavg for 1, 5, 15 minutes max
# test		$rc = compare(1,1,1);	# loadavg for 1, 5, 15 minutes max

		openlog($program, 'cons,pid', 'user');
		syslog('info', 'load-checking.');
		closelog();

		if ($rc == $NOTEQUAL)
		{
			open(LOAD,$LAVG) ||
				print STDERR "ERROR: Cannot read load average: $!";
			my $line = <LOAD>;
			close LOAD;

			openlog($program, 'cons,pid', 'user');
			syslog('info', 'load-avg is high: '. $line);
			closelog();

			$infotxt  = "----------------------------------------\n";
			$infotxt .= "Attention! server-load is high! \n";
			$infotxt .= "----------------------------------------\n";
			$infotxt .= "current load average status:\n";
			$infotxt .= "----------------------------------------\n";
			$infotxt .= "$line";
			$infotxt .= "----------------------------------------\n";
			$infotxt .= "please check your server.\n";
			$infotxt .= "load-status-check is sponsored by http://kapper.net/\n";
		}
		
		if (($callparam & $SEND) == $SEND)
		{
			if ($infotxt ne "")
			{
				# set mail parameters for sending
				%mail = ( To   =>    $mailadr,
				          From =>    $mailadr,
				          Subject => $SUBJECT,
				          Message => $infotxt
				         );#
				sendmail(%mail) or die   $Mail::Sendmail::error;
				#print "OK. Log says:\n", $Mail::Sendmail::log;
			}
		}
		else
		{
			if ($infotxt)		# if param = --check without email
			{
				print STDOUT "\n$infotxt\n";	
			}
		}			
	}
	

} # end main