plugin-pg__connections: pg__connections

#!/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__connections \
#         /etc/munin/plugins/pg_<databasename>_connections
#       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/7.4/interactive/monitoring-stats.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 $dbuserx = $ENV{'dbuserx'} || '';
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") {
        my $sql_max = "SHOW max_connections;";
        my $sth_max = $dbh->prepare($sql_max);
        $sth_max->execute();
        my ($max_connections) = $sth_max->fetchrow();
        my $warning = int ($max_connections * 0.7);
        my $critical = int ($max_connections * 0.8);
        print "graph_title PostgresSQL active connections\n";
        print "graph_args -l 0 --base 1000\n";
        print "graph_vlabel Connections\n";
        print "graph_category Postgresql\n";
        print "graph_info Shows active Postgresql connections from $dbname\n";
        

        my $sql = "select datname, count(*) from pg_stat_activity group by datname";
        my $sth = $dbh->prepare($sql);
        $sth->execute();
        my $setarea = "yes";
        while ( my ($datname,$curr_conn) = $sth->fetchrow_array ) {
                print "$datname.label $datname active connections\n";
                print "$datname.info $datname active connections\n";
                print "$datname.type GAUGE\n";
                if ($setarea eq "yes") {
                        print "$datname.draw AREA\n";
                        $setarea="";
                } else {
                        print "$datname.draw STACK\n";
                }
        }

        print "max_connections.label Max. connections\n";
        print "max_connections.info Max. connections\n";
        print "max_connections.type GAUGE\n";

        print "warning $warning\n";
        print "critical $critical\n";
        exit 0;
    }
}


# select datname, count(*) from pg_stat_activity group by datname
my $sql_max = "SHOW max_connections;";
my $sth_max = $dbh->prepare($sql_max);
$sth_max->execute();
my ($max_connections) = $sth_max->fetchrow();

#my $sql = "SELECT COUNT (*) FROM pg_stat_activity;";
my $sql = "select datname, count(*) from pg_stat_activity group by datname";
my $sth = $dbh->prepare($sql);
$sth->execute();
while ( my ($datname,$curr_conn) = $sth->fetchrow_array ) {
        print "$datname.value $curr_conn\n";
}
print "max_connections.value $max_connections\n";