#!/usr/bin/perl -w

use strict;
use Getopt::Long;
use DBI;

my $options = { 'master' => 'master.host', 'slave' => 'slave.host', 'crit' => 100000, 'warn' => 10000 , 'dbuser' => 'root', 'dbpass' => 'bla', "masterport" => "", 'slaveport' => ''};
GetOptions($options, "master=s", "slave=s", "dbuser=s", "dbpass=s", "crit=i", "warn=i", "help");
my $max_binlog;

if (defined $options->{'help'}) {
	print <<FOO;
$0: check replication between mysql databases

 check_replication.pl [ --master <host> ] [ --slave <host> ]
 [ --crit <positions> ] [ --warn <positions> ] [ --dbuser <user> ]
 [ --dbpass <pass> ]

  --master <host>    - MySQL instance running as a master server
  --slave <host>     - MySQL instance running as a slave server
  --masterport <port>      - port number MySQL master is listening on
  --slaveport <port>      - port number MySQL slave is listening on
  --crit <positions> - Number of binlog positions for critical state
  --warn <positions> - Number of binlog positions for warning state
  --dbuser <user>    - Username with File and Process privs to check status
  --dbpass <pass>    - Password for above user
  --help             - This help page

The user that is testing must be the same on all instances, eg:
  GRANT File, Process on *.* TO repl_test\@192.168.0.% IDENTIFIED BY <pass>

Note: Any mysqldump tables (for backups) may lock large tables for a long
time. If you dump from your slave for this, then your master will gallop
away from your slave, and the difference will become large. The trick is to
set crit above this differnce and warn below.

(c) 2004 Fotango. James Bromberger <jbromberger\@fotango.com>.
(c) 2006 Some changes by Robert Klikics <robert\@klikics.de>.
(c) 2012 Small changes by Maxime Augier <max\@xolus.net>.

FOO
exit;
}

sub get_status {
	my $host = shift;
    my $port = shift;
	my $role = shift;
    require Carp;
    Carp::cluck "host" if !defined $host;
    Carp::cluck "port" if !defined $port;
    Carp::cluck "dbuser" if !defined $options->{'dbuser'};
    Carp::cluck "dbpass" if !defined $options->{'dbpass'};
	my $dbh = DBI->connect("DBI:mysql:host=$host;port=$port", $options->{'dbuser'}, $options->{'dbpass'});
	if (not $dbh) {
		print "UNKNOWN: cannot connect to $host";
		exit 3;
	}

	if (lc ($role) eq 'master') {
		my $sql1 = "show variables like 'max_binlog_size'";
		my $sth1 = $dbh->prepare($sql1);
		my $res1 = $sth1->execute;
		my $ref1 = $sth1->fetchrow_hashref;
		$max_binlog = $ref1->{'Value'};
	}
	my $sql = sprintf "SHOW %s STATUS", $role;
	my $sth = $dbh->prepare($sql);
	my $res = $sth->execute;
	if (not $res) {
		die "No results";
	}
	my $ref = $sth->fetchrow_hashref;
	$sth->finish;
	#print "$host:\n";
	#print join (', ', map { sprintf " %s: %s", $_, $ref->{$_} } keys %{$ref}) . "\n";
	$dbh->disconnect;
	return $ref;
}

sub compare_status {
	my ($a, $b) = @_;
	my ($master, $slave);
	if (defined($a->{'File'})) {
		$master = $a;
		$slave = $b;
	} elsif (defined($b->{'File'})) {
		$master = $b;
		$slave = $a;
	}
	$master->{'File_No'} = $1 if ($master->{'File'} =~ /(\d+)$/);
	$slave->{'File_No'} = $1 if ($slave->{'Relay_Master_Log_File'} =~ /(\d+)$/);


	my $diff = ($master->{'File_No'} - $slave->{'File_No'}) * $max_binlog;
	#printf "Master: %d Slave: %d\n", $master->{'Position'}, $slave->{'Exec_Master_Log_Pos'};
	$diff+= $master->{'Position'} - $slave->{'Exec_master_log_pos'};
	my $state = sprintf "Master: %d/%d  Slave: %d/%d  Diff: %d/%d\n", $master->{'File_No'}, $master->{'Position'}, $slave->{'File_No'}, $slave->{'Exec_master_log_pos'}, ($diff/$max_binlog), ($diff % $max_binlog);
	if ($diff >= $options->{'crit'}) {
		print "CRITICAL: $state";
		exit 2;
	} elsif ($diff >= $options->{'warn'}) {
		print "WARN: $state";
		exit 1;
	}
	print "OK: $state";
	exit 0;
}

compare_status(get_status($options->{'slave'}, $options->{'slaveport'}, 'slave'), get_status($options->{'master'}, $options->{'masterport'}, 'master'));