plugin-pg__database_blks: pg__database_blks

#!/usr/bin/perl -w
# Plugin for monitor postgres database reads.
#
# 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_database__blks \
#         /etc/munin/plugins/pg_database_<databasename>_blks
#       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 $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 "no Unable to access Database $dbname on host $dbhost as user $dbuser.\nError returned was: ". $DBI::errstr;
            exit 1;
        }

        #is Collects block-level statistics on database activity on?
        my $sql = "show stats_block_level;";
        my $sth = $dbh->prepare($sql);
        $sth->execute();
        my ($stats_block_level) = $sth->fetchrow();     
        if ( $stats_block_level eq "off" ) {
           print "no Collects block-level statistics on database activity is off (stats_block_level=off)\n";
           exit 1;
        }
        
        # all is OK
        print "yes\n";
        exit 0;
        
    }

    if ($ARGV[0] eq "config") {
        print "graph_title PostgreSQL data reads from $dbname\n";
        print "graph_args --base 1000\n";
        print "graph_vlabel Blocks read per \${graph_period}\n";
        print "graph_category Postgresql\n";
        print "graph_info Shows number of blocks read from disk and from memory\n";
        print "blks_read.label Read from disk\n";
        print "blks_read.info Read from disk\n";
        print "blks_read.type DERIVE\n";
        print "blks_read.min 0\n";
        print "blks_read.draw AREA\n";
        print "blks_hit.label Cached in memory\n";
        print "blks_hit.info Cached in memory\n";
        print "blks_hit.type DERIVE\n";
        print "blks_hit.min 0\n";
        print "blks_hit.draw STACK\n";
        exit 0;
    }
}


my $sql = "select blks_read,blks_hit from pg_stat_database where datname='$dbname';";
my $sth = $dbh->prepare($sql);
$sth->execute();
my ($blks_read,$blks_hit) = $sth->fetchrow();
print "blks_read.value $blks_read\n";
print "blks_hit.value $blks_hit\n";