Perl Script to Monitor MySQL Replication and Send Email on Failure

monitor_mysql.pl

#!/usr/bin/perl

use DBI;
use Email::MIME;
use Log::Log4perl qw(get_logger :levels);
use Data::Dumper;

use strict;

# For backgrounding
my $pid = fork();
#my $pid = 0;

if (!defined $pid)
{
	die "Cannot fork:$!\n";
}
elsif ($pid == 0)
{
	do_monitor();
}
else
{
	print "Forked. Running in background.\n";
}

sub do_monitor()
{
	# logging
	my $logger = get_logger('mysql');
	$logger->level($INFO);

	my $layout = Log::Log4perl::Layout::PatternLayout->new("%d %p> %m%n");

	my $fileAppender = Log::Log4perl::Appender->new(
		"Log::Dispatch::File",
		filename => "/tmp/monitor_mysql.log",
		mode => "append");
	$fileAppender->layout($layout);

	#my $screenAppender = Log::Log4perl::Appender->new("Log::Dispatch::Screen", newline => 1);
	#$screenAppender->layout($layout);

	$logger->add_appender($fileAppender);
	#$logger->add_appender($screenAppender);

	# MySQL
	my $dsn = "DBI:mysql:database=mysql:$ARGV[0];mysql_read_default_group=client";
	my $dbh = DBI->connect($dsn);
	if (!$dbh)
	{
	        die $DBI::errstr;
	}

	my $sentNotification = 0;

	while(1)
	{
        	my $sth = $dbh->prepare("SHOW SLAVE STATUS") or die $DBI::errstr;
        	$sth->execute or die $DBI::errstr;
        	my $r = $sth->fetchrow_hashref();
        	$sth->finish;

        	if ($$r{'Slave_SQL_Running'} eq "No" || $$r{'Slave_IO_Running'} eq "No")
        	{
			$logger->error("Slave replication broken: ");
			$logger->info(Dumper($r));

			sendEmail($sentNotification);
			$sentNotification = 1;
		}
		else
		{
			# OK or possibly Recovered
			$logger->info("Slave replication OK");
			$sentNotification = 0;
		}

	        sleep 60;
	}
}

sub sendEmail
{
	my $sentNotif = shift;

	if ($sentNotif == 0)
	{
		my $message = Email::MIME->create(
			header_str => [
				From => '[email protected]',
				To => '[email protected]',
				Subject => 'MySQL-Master-DB Replication Failure'
			],
			attributes => { encoding => 'quoted-printable', charset => 'ISO-8859-1' },
			body_str => "Slave is not running.");

		use Email::Sender::Simple qw(sendmail);
		sendmail($message);
	}
}