#!/usr/bin/perl -w
# Plugin for monitor postgres connections.
#
# Licenced under GPL v2.
#
# Usage:
#
#       Symlink into /etc/munin/plugins/ and add the monitored
#       database to the filename. e.g.:
#
#       ln -s /usr/share/munin/plugins/pg__locks \
#         /etc/munin/plugins/pg_<databasename>_locks
#       This should, however, be given through autoconf and suggest.
#
#       If required, give username, password and/or Postgresql server
#       host through environment variables.
#
#       You must also activate Postgresql statistics. See
#	http://www.postgresql.org/docs/8.1/interactive/monitoring-locks.html
#       for how to enable this. Specifically, the following lines must
#       exist in your postgresql.conf:
#
#           stats_start_collector = true
#           stats_block_level = true
#
#
# Parameters:
#
#       config   (required)
#
# Config variables:
#
#       dbhost     - Which database server to use. Defaults to
#                    'localhost'.
#       dbname     - Which database to use. Defaults to template1
#       dbuser     - A Postgresql user account with read permission to
#                    the given database. Defaults to
#                    'postgres'. Anyway, Munin must be told which user
#                    this plugin should be run as.
#       dbpass     - The corresponding password, if
#                    applicable. Default to undef. Remember that
#                    pg_hba.conf must be configured accordingly.
#
# Magic markers
#%# family=auto
#%# capabilities=autoconf

use strict;
use DBI;

my $dbhost = $ENV{'dbhost'} || '127.0.0.1';
my $dbname = $ENV{'dbname'} || 'template1';
my $dbuser = $ENV{'dbuser'} || 'postgres';
my $dbport = $ENV{'dbport'} || '5432';
my $dbpass = $ENV{'dbpass'} || '';

# Check for DBD::Pg
if (! eval "require DBD::Pg;") {
     exit 1;
}

my $dsn = "DBI:Pg:dbname=$dbname;host=$dbhost;port=$dbport";
#print "$dsn\n";
my $dbh = DBI->connect ($dsn, $dbuser,
			$dbpass,
			{RaiseError =>1}) || die "";



if (exists $ARGV[0]) {
    if ($ARGV[0] eq 'autoconf') {
	# Check for DBD::Pg
	if (! eval "require DBD::Pg;") {
	     print "no (DBD::Pg not found)";
	     exit 1;
	}
        if ($dbh) {
            print "yes\n";
            exit 0;
        } else {
            print "no Unable to access Database $dbname on host $dbhost as user $dbuser.\nError returned was: ". $DBI::errstr;
            exit 1;
	}
    }

    if ($ARGV[0] eq "config") {
	print "graph_title PostgresSQL locks\n";
	print "graph_args --base 1000\n";
	print "graph_vlabel Locks\n";
	print "graph_category Postgresql\n";
	print "graph_info Shows Postgresql locks\n";
	print "locks.label Locks\n";
	print "locks.info Locks (more info here, please... :)\n";
	print "locks.type GAUGE\n";
	print "locks.warning 5\n";
	print "locks.critical 10\n";
	print "exlocks.label Exclusive locks\n";
	print "exlocks.info Exclusive locks (here too, please... :)\n";
	print "exlocks.type GAUGE\n";
	print "exlocks.warning 5\n";
	print "exlocks.critical 10\n";
	exit 0;
    }
}

my $sql="SELECT mode,COUNT(mode) FROM pg_locks GROUP BY mode ORDER BY mode;";
my $sth = $dbh->prepare ($sql);
$sth->execute ();
my $locks = 0;
my $exlocks = 0;
while (my ($mode, $count) = $sth->fetchrow ()) {
    if ($mode =~ /exclusive/i) {
        $exlocks = $exlocks + $count;
    }
    $locks = $locks+$count;
}
print "locks.value $locks\n";
print "exlocks.value $exlocks\n";