Jonathan's blog

I’ve now written several Nagios plugins and submitted them all to MonitoringExchange.

Here’s a quick summary:

• check_temper for monitoring the temperature with a TEMPer USB thermometer
• check_kernel for checking that the currently running kernel on an RPM-based system is the most recent installed kernel (not necessarily the latest available kernel in the repository)
• check_aql_balance for monitoring the number of SMS text message credits on your AQL account^[1]
• check_k8temp for monitoring the temperature of an AMD K8 (e.g. Athlon or Sempron) CPU

Further to yesterday’s post about setting up SMS alerts from Nagios, I decided I wanted to monitor how many SMS credits I have left in my account.

AQL provide a way of finding out via an HTTP request, so I set about writing a perl module to check and return the result to Nagios.

N.B. I’ve now published this module on Monitoring Exchange. Please download the plugin from there, as I will keep that copy up to date if there are changes in the future (and the copy on this page is likely to go out of date).

check_aql_balance

#! /usr/bin/perl -w
# Usage: check_aql_balance [username] [password] [warning] [critical]
# Example: check_raid fred bloggs 100 50
#         WARNING Balance 23 credits

use strict;
use LWP::Simple;
use lib "/usr/local/nagios/libexec";
use utils qw(%ERRORS);

my $username = $ARGV[0];
my $password = $ARGV[1];
my $warningval;
my $criticalval;
$warningval = $ARGV[2] or $warningval = 20;
$criticalval = $ARGV[3] or $criticalval = 10;
$warningval =~ s/[^0-9]//gi;
$criticalval =~ s/[^0-9]//gi;

if (!defined $username || !defined $password) {
    print "UNKNOWN, Unable to retrieve account balance\n";
    exit $ERRORS{'UNKNOWN'};
}

my $url = "http://gw1.aql.com/sms/postmsg.php?username=$username&password=$password&cmd=credit";
my $content = get $url;

if (!defined $content) {
    print "UNKNOWN, Unable to retrieve account balance\n";
    exit $ERRORS{'UNKNOWN'};
} elsif ($content =~ m/AUTHERROR/i) {
    print "UNKNOWN, Unable to retrieve account balance\n";
    exit $ERRORS{'UNKNOWN'};
}

$content =~ s/[^0-9]//gi;
if ($content >=0) {
    if ($content < $criticalval) {
        # critical
        print "CRITICAL, Balance $content credits\n";
        exit $ERRORS{'CRITICAL'};
    } elsif ($content < $warningval) {
        # warning
        print "WARNING, Balance $content credits\n";
        exit $ERRORS{'WARNING'};
    } else {
        # ok
        print "OK, Balance $content credits\n";
        exit $ERRORS{'OK'};
    }
} else {
    # invalid number
    print "UNKNOWN ,Unable to retrieve account balance\n";
    exit $ERRORS{'UNKNOWN'};
}

The only required arguments are the AQL username and password, but you can optionally specify the limits that trigger Warning or Critical status. If you omit these, the script defaults to values of 20 and 10.

In your commands.cfg, add a block like this to define the command. Again, you can omit the last 2 parameters if you are happy with the defaults..

define command{
    command_name    check_aql_balance
    command_line    $USER1$/check_aql_balance $ARG1$ $ARG2$ $ARG3$ $ARG4$
}

And finally, in the localhost.cfg (or any other config file for hosts/services) you can add the service like this.

define service{
    use                             local-service
    host_name                       localhost
    service_description             AQL account balance
    check_command                   check_aql_balance!fred!bloggs!20!10
    notifications_enabled           1
}

Simples!