Description

This document introduces the best practices in the development of “centreon-plugins”.

As all plugins are written in Perl, “there is more than one way to do it”. But to avoid reinventing the wheel, you should first take a look at the “example” directory, you will get an overview of how to build your own plugin and associated modes.

The lastest version is available on following git repository: http://git.centreon.com/centreon-plugins.git

Quick Start

Directory creation

First of all, you need to create a directory on the git to store the new plugin.

Root directories are organized by section:

  • Application : apps
  • Database : database
  • Hardware : hardware
  • network equipment : network
  • Operating System : os
  • Storage equipment : storage

According to the monitored object, it exists an organization which can use:

  • Type
  • Constructor
  • Model
  • Monitoring Protocol

For example, if you want to add a plugin to monitor Linux by SNMP, you need to create this directory:

$ mkdir -p os/linux/snmp

You also need to create a “mode” directory for futures modes:

$ mkdir os/linux/snmp/mode

Plugin creation

Once the directory is created, create the plugin file inside it:

$ touch plugin.pm

Then, edit plugin.pm to add license terms by copying it from an other plugin. Don’t forget to put your name at the end of it:

# ...
# Authors : <your name> <<your email>>

Next, describe your package name : it matches your plugin directory.

package path::to::plugin;

Declare used libraries (strict and warnings are mandatory). Centreon libraries are described later:

use strict;
use warnings;
use base qw(**centreon_library**);

The plugin need a new constructor to instantiate the object:

sub new {
      my ($class, %options) = @_;
      my $self = $class->SUPER::new(package => __PACKAGE__, %options);
      bless $self, $class;

      ...

      return $self;
}

Plugin version must be declared in the new constructor:

$self->{version} = '0.1';

Several modes can be declared in the new constructor:

%{$self->{modes}} = (
                      'mode1'    => '<plugin_path>::mode::mode1',
                      'mode2'    => '<plugin_path>::mode::mode2',
                      ...
                      );

Then, declare the module:

1;

A description of the plugin is needed to generate the documentation:

__END__

=head1 PLUGIN DESCRIPTION

<Add a plugin description here>.

=cut

Tip

You can copy-paste an other plugin.pm and adapt some lines (package, arguments...).

Tip

The plugin has ”.pm” extension because it’s a Perl module. So don’t forget to add 1; at the end of the file.

Mode creation

Once plugin.pm is created and modes are declared in it, create modes in the mode directory:

cd mode
touch mode1.pm

Then, edit mode1.pm to add license terms by copying it from an other mode. Don’t forget to put your name at the end of it:

# ...
# Authors : <your name> <<your email>>

Next, describe your package name: it matches your mode directory.

package path::to::plugin::mode::mode1;

Declare used libraries (always the same):

use strict;
use warnings;
use base qw(centreon::plugins::mode);

The mode needs a new constructor to instantiate the object:

sub new {
      my ($class, %options) = @_;
      my $self = $class->SUPER::new(package => __PACKAGE__, %options);
      bless $self, $class;

      ...

      return $self;
}

Mode version must be declared in the new constructor:

$self->{version} = '1.0';

Several options can be declared in the new constructor:

$options{options}->add_options(arguments =>
                              {
                                "option1:s" => { name => 'option1' },
                                "option2:s" => { name => 'option2', default => 'value1' },
                                "option3"   => { name => 'option3' },
                              });

Here is the description of arguments used in this example:

  • option1 : String value
  • option2 : String value with default value “value1”
  • option3 : Boolean value

Tip

You can have more informations about options format here: http://perldoc.perl.org/Getopt/Long.html

The mode need a check_options method to validate options:

sub check_options {
  my ($self, %options) = @_;
  $self->SUPER::init(%options);
  ...
}

For example, Warning and Critical thresholds must be validate in check_options method:

if (($self->{perfdata}->threshold_validate(label => 'warning', value => $self->{option_results}->{warning})) == 0) {
     $self->{output}->add_option_msg(short_msg => "Wrong warning threshold '" . $self->{option_results}->{warning} . "'.");
     $self->{output}->option_exit();
  }
if (($self->{perfdata}->threshold_validate(label => 'critical', value => $self->{option_results}->{critical})) == 0) {
     $self->{output}->add_option_msg(short_msg => "Wrong critical threshold '" . $self->{option_results}->{critical} . "'.");
     $self->{output}->option_exit();
}

In this example, help is printed if thresholds do not have a correct format.

Then comes the run method, where you perform measurement, check thresholds, display output and format performance datas. This is an example to check a SNMP value:

sub run {
  my ($self, %options) = @_;
  $self->{snmp} = $options{snmp};
  $self->{hostname} = $self->{snmp}->get_hostname();

  my $result = $self->{snmp}->get_leef(oids => [$self->{option_results}->{oid}], nothing_quit => 1);
  my $value = $result->{$self->{option_results}->{oid}};

  my $exit = $self->{perfdata}->threshold_check(value => $value,
                             threshold => [ { label => 'critical', 'exit_litteral' => 'critical' }, { label => 'warning', exit_litteral => 'warning' } ]);
  $self->{output}->output_add(severity => $exit,
                              short_msg => sprintf("SNMP Value is %s.", $value));

  $self->{output}->perfdata_add(label => 'value', unit => undef,
                                value => $value,
                                warning => $self->{perfdata}->get_perfdata_for_output(label => 'warning'),
                                critical => $self->{perfdata}->get_perfdata_for_output(label => 'critical'),
                                min => undef, max => undef);

  $self->{output}->display();
  $self->{output}->exit();
}

In this example, we check a SNMP OID that we compare to warning and critical thresholds. There are the methods which we use:

  • get_leef : get a SNMP value from an OID
  • threshold_check : compare SNMP value to warning and critical thresholds
  • output_add : add output
  • perfdata_add : add perfdata to output
  • display : display output
  • exit : exit

Then, declare the module:

1;

A description of the mode and its arguments is needed to generate the documentation:

__END__

=head1 PLUGIN DESCRIPTION

<Add a plugin description here>.

=cut

Commit and push

Before committing the plugin, you need to create an enhancement ticket on the centreon-plugins forge : http://forge.centreon.com/projects/centreon-plugins

Once plugin and modes are developed, you can commit (commit messages in english) and push your work:

git add path/to/plugin
git commit -m "Add new plugin for XXXX refs #<ticked_id>"
git push

Libraries reference

This chapter describes Centreon libraries which you can use in your development.

Output

This library allows you to build output of your plugin.

output_add

Description

Add string to output (print it with display method). If status is different than ‘ok’, output associated with ‘ok’ status is not printed.

Parameters

Parameter Type Default Description
severity String OK Status of the output.
separator String - Separator between status and output string.
short_msg String   Short output (first line).
long_msg String   Long output (used with –verbose option).

Example

This is an example of how to manage output:

$self->{output}->output_add(severity  => 'OK',
                            short_msg => 'All is ok');
$self->{output}->output_add(severity  => 'Critical',
                            short_msg => 'There is a critical problem');
$self->{output}->output_add(long_msg  => 'Port 1 is disconnected');

$self->{output}->display();

Output displays :

CRITICAL - There is a critical problem
Port 1 is disconnected

perfdata_add

Description

Add performance data to output (print it with display method). Performance data are displayed after ‘|’.

Parameters

Parameter Type Default Description
label String   Label of the performance data.
value Int   Value of the performance data.
unit String   Unit of the performance data.
warning String   Warning threshold.
critical String   Critical threshold.
min Int   Minimum value of the performance data.
max Int   Maximum value of the performance data.

Example

This is an example of how to add performance data:

$self->{output}->output_add(severity  => 'OK',
                            short_msg => 'Memory is ok');
$self->{output}->perfdata_add(label    => 'memory_used',
                              value    => 30000000,
                              unit     => 'B',
                              warning  => '80000000',
                              critical => '90000000',
                              min      => 0,
                              max      => 100000000);

$self->{output}->display();

Output displays:

OK - Memory is ok | 'memory_used'=30000000B;80000000;90000000;0;100000000

Perfdata

This library allows you to manage performance data.

get_perfdata_for_output

Description

Manage thresholds of performance data for output.

Parameters

Parameter Type Default Description
label String   Threshold label.
total Int   Percent threshold to transform in global.
cast_int Int (0 or 1)   Cast absolute to int.
op String   Operator to apply to start/end value (uses with ‘value’).
value Int   Value to apply with ‘op’ option.

Example

This is an example of how to manage performance data for output:

my $format_warning_perfdata  = $self->{perfdata}->get_perfdata_for_output(label => 'warning', total => 1000000000, cast_int => 1);
my $format_critical_perfdata = $self->{perfdata}->get_perfdata_for_output(label => 'critical', total => 1000000000, cast_int => 1);

$self->{output}->perfdata_add(label    => 'memory_used',
                              value    => 30000000,
                              unit     => 'B',
                              warning  => $format_warning_perfdata,
                              critical => $format_critical_perfdata,
                              min      => 0,
                              max      => 1000000000);

Tip

In this example, instead of print warning and critical thresholds in ‘percent’, the function calculates and prints these in ‘bytes’.

threshold_validate

Description

Validate and affect threshold to a label.

Parameters

Parameter Type Default Description
label String   Threshold label.
value String   Threshold value.

Example

This example checks if warning threshold is correct:

if (($self->{perfdata}->threshold_validate(label => 'warning', value => $self->{option_results}->{warning})) == 0) {
  $self->{output}->add_option_msg(short_msg => "Wrong warning threshold '" . $self->{option_results}->{warning} . "'.");
  $self->{output}->option_exit();
}

Tip

You can see the correct threshold format here: https://nagios-plugins.org/doc/guidelines.html#THRESHOLDFORMAT

threshold_check

Description

Check performance data value with threshold to determine status.

Parameters

Parameter Type Default Description
value Int   Performance data value to compare.
threshold String array   Threshold label to compare and exit status if reached.

Example

This example checks if performance data reached thresholds:

$self->{perfdata}->threshold_validate(label => 'warning', value => 80);
$self->{perfdata}->threshold_validate(label => 'critical', value => 90);
my $prct_used = 85;

my $exit = $self->{perfdata}->threshold_check(value => $prct_used, threshold => [ { label => 'critical', 'exit_litteral' => 'critical' }, { label => 'warning', exit_litteral => 'warning' } ]);

$self->{output}->output_add(severity  => $exit,
                            short_msg => sprint("Used memory is %i%%", $prct_used));
$self->{output}->display();

Output displays:

WARNING - Used memory is 85% |

change_bytes

Description

Convert bytes to human readable unit. Return value and unit.

Parameters

Parameter Type Default Description
value Int   Performance data value to convert.
network   1024 Unit to divide (1000 if defined).

Example

This example change bytes to human readable unit:

my ($value, $unit) = $self->{perfdata}->change_bytes(value => 100000);

print $value.' '.$unit."\n";

Output displays:

100 KB

Snmp

This library allows you to use SNMP protocol in your plugin. To use it, add the following line at the beginning of your plugin.pm:

use base qw(centreon::plugins::script_snmp);

get_leef

Description

Return hash table table of SNMP values for multiple OIDs (do not work with SNMP table).

Parameters

Parameter Type Default Description
oids String array   Array of OIDs to check (Can be set by ‘load’ method).
dont_quit Int (0 or 1) 0 Don’t quit even if an snmp error occured.
nothing_quit Int (0 or 1) 0 Quit if no value is returned.

Example

This is an example of how to get 2 SNMP values:

my $oid_hrSystemUptime = '.1.3.6.1.2.1.25.1.1.0';
my $oid_sysUpTime = '.1.3.6.1.2.1.1.3.0';

my $result = $self->{snmp}->get_leef(oids => [ $oid_hrSystemUptime, $oid_sysUpTime ], nothing_quit => 1);

print $result->{$oid_hrSystemUptime}."\n";
print $result->{$oid_sysUpTime}."\n";

load

Description

Load a range of OIDs to use with get_leef method.

Parameters

Parameter Type Default Description
oids String array   Array of OIDs to check.
instances Int array   Array of OID instances to check.
instance_regexp String   Regular expression to get instances from instances option.
begin Int   Instance to begin
end Int   Instance to end

Example

This is an example of how to get 4 instances of a SNMP table by using load method:

my $oid_dskPath = '.1.3.6.1.4.1.2021.9.1.2';

$self->{snmp}->load(oids => [$oid_dskPercentNode], instances => [1,2,3,4]);

my $result = $self->{snmp}->get_leef(nothing_quit => 1);

use Data::Dumper;
print Dumper($result);

This is an example of how to get multiple instances dynamically (memory modules of Dell hardware) by using load method:

my $oid_memoryDeviceStatus = '.1.3.6.1.4.1.674.10892.1.1100.50.1.5';
my $oid_memoryDeviceLocationName = '.1.3.6.1.4.1.674.10892.1.1100.50.1.8';
my $oid_memoryDeviceSize = '.1.3.6.1.4.1.674.10892.1.1100.50.1.14';
my $oid_memoryDeviceFailureModes = '.1.3.6.1.4.1.674.10892.1.1100.50.1.20';

my $result = $self->{snmp}->get_table(oid => $oid_memoryDeviceStatus);
$self->{snmp}->load(oids => [$oid_memoryDeviceLocationName, $oid_memoryDeviceSize, $oid_memoryDeviceFailureModes],
                    instances => [keys %$result],
                    instance_regexp => '(\d+\.\d+)$');

my $result2 = $self->{snmp}->get_leef();

use Data::Dumper;
print Dumper($result2);

get_table

Description

Return hash table of SNMP values for SNMP table.

Parameters

Parameter Type Default Description
oid String   OID of the snmp table to check.
start Int   First OID to check.
end Int   Last OID to check.
dont_quit Int (0 or 1) 0 Don’t quit even if an SNMP error occured.
nothing_quit Int (0 or 1) 0 Quit if no value is returned.
return_type Int (0 or 1) 0 Return a hash table with one level instead of multiple.

Example

This is an example of how to get a SNMP table:

my $oid_rcDeviceError            = '.1.3.6.1.4.1.15004.4.2.1';
my $oid_rcDeviceErrWatchdogReset = '.1.3.6.1.4.1.15004.4.2.1.2.0';

my $results = $self->{snmp}->get_table(oid => $oid_rcDeviceError, start => $oid_rcDeviceErrWatchdogReset);

use Data::Dumper;
print Dumper($results);

get_multiple_table

Description

Return hash table of SNMP values for multiple SNMP tables.

Parameters

Parameter Type Default Description
oids Hash table   Hash table of OIDs to check (Can be set by ‘load’ method). Keys can be: “oid”, “start”, “end”.
dont_quit Int (0 or 1) 0 Don’t quit even if an SNMP error occured.
nothing_quit Int (0 or 1) 0 Quit if no value is returned.
return_type Int (0 or 1) 0 Return a hash table with one level instead of multiple.

Example

This is an example of how to get 2 SNMP tables:

my $oid_sysDescr        = ".1.3.6.1.2.1.1.1";
my $aix_swap_pool       = ".1.3.6.1.4.1.2.6.191.2.4.2.1";

my $results = $self->{snmp}->get_multiple_table(oids => [
                                                      { oid => $aix_swap_pool, start => 1 },
                                                      { oid => $oid_sysDescr },
                                                ]);

use Data::Dumper;
print Dumper($results);

get_hostname

Description

Get hostname parameter (useful to get hostname in mode).

Parameters

None.

Example

This is an example of how to get hostname parameter:

my $hostname = $self->{snmp}->get_hostname();

get_port

Description

Get port parameter (useful to get port in mode).

Parameters

None.

Example

This is an example of how to get port parameter:

my $port = $self->{snmp}->get_port();

oid_lex_sort

Description

Return sorted OIDs.

Parameters

Parameter Type Default Description
- String array   Array of OIDs to sort.

Example

This example prints sorted OIDs:

foreach my $oid ($self->{snmp}->oid_lex_sort(keys %{$self->{results}->{$my_oid}})) {
  print $oid;
}

Misc

This library provides a set of miscellaneous methods. To use it, you can directly use the path of the method:

centreon::plugins::misc::<my_method>;

trim

Description

Strip whitespace from the beginning and end of a string.

Parameters

Parameter Type Default Description
- String   String to strip.

Example

This is an example of how to use trim method:

my $word = '  Hello world !  ';
my $trim_word =  centreon::plugins::misc::trim($word);

print $word."\n";
print $trim_word."\n";

Output displays :

Hello world !

change_seconds

Description

Convert seconds to human readable text.

Parameters

Parameter Type Default Description
- Int   Number of seconds to convert.

Example

This is an example of how to use change_seconds method:

my $seconds = 3750;
my $human_readable_time =  centreon::plugins::misc::change_seconds($seconds);

print 'Human readable time : '.$human_readable_time."\n";

Output displays:

Human readable time : 1h 2m 30s

backtick

Description

Execute system command.

Parameters

Parameter Type Default Description
command String   Command to execute.
arguments String array   Command arguments.
timeout Int 30 Command timeout.
wait_exit Int (0 or 1) 0 Command process ignore SIGCHLD signals.
redirect_stderr Int (0 or 1) 0 Print errors in output.

Example

This is an example of how to use backtick method:

my ($error, $stdout, $exit_code) = centreon::plugins::misc::backtick(
                                    command => 'ls /home',
                                    timeout => 5,
                                    wait_exit => 1
                                    );

print $stdout."\n";

Output displays files in ‘/home’ directory.

execute

Description

Execute command remotely.

Parameters

Parameter Type Default Description
output Object   Plugin output ($self->{output}).
options Object   Plugin options ($self->{option_results}) to get remote options.
sudo String   Use sudo command.
command String   Command to execute.
command_path String   Command path.
command_options String   Command arguments.

Example

This is an example of how to use execute method. We suppose --remote option is enabled:

my $stdout = centreon::plugins::misc::execute(output => $self->{output},
                                              options => $self->{option_results},
                                              sudo => 1,
                                              command => 'ls /home',
                                              command_path => '/bin/',
                                              command_options => '-l');

Output displays files in /home using ssh on a remote host.

windows_execute

Description

Execute command on Windows.

Parameters

Parameter Type Default Description
output Object   Plugin output ($self->{output}).
command String   Command to execute.
command_path String   Command path.
command_options String   Command arguments.
timeout Int   Command timeout.
no_quit Int   Don’t quit even if an error occured.

Example

This is an example of how to use windows_execute method.

my $stdout = centreon::plugins::misc::windows_execute(output => $self->{output},
                                                      timeout => 10,
                                                      command => 'ipconfig',
                                                      command_path => '',
                                                      command_options => '/all');

Output displays IP configuration on a Windows host.

Statefile

This library provides a set of methods to use a cache file. To use it, add the following line at the beginning of your mode:

use centreon::plugins::statefile;

read

Description

Read cache file.

Parameters

Parameter Type Default Description
statefile String   Name of the cache file.
statefile_dir String   Directory of the cache file.
memcached String   Memcached server to use.

Example

This is an example of how to use read method:

$self->{statefile_value} = centreon::plugins::statefile->new(%options);
$self->{statefile_value}->check_options(%options);
$self->{statefile_value}->read(statefile => 'my_cache_file',
                               statefile_dir => '/var/lib/centreon/centplugins'
                              );

use Data::Dumper;
print Dumper($self->{statefile_value});

Output displays cache file and its parameters.

get

Description

Get data from cache file.

Parameters

Parameter Type Default Description
name String   Get a value from cache file.

Example

This is an example of how to use get method:

$self->{statefile_value} = centreon::plugins::statefile->new(%options);
$self->{statefile_value}->check_options(%options);
$self->{statefile_value}->read(statefile => 'my_cache_file',
                               statefile_dir => '/var/lib/centreon/centplugins'
                              );

my $value = $self->{statefile_value}->get(name => 'property1');
print $value."\n";

Output displays value for ‘property1’ of the cache file.

write

Description

Write data to cache file.

Parameters

Parameter Type Default Description
data String   Data to write in cache file.

Example

This is an example of how to use write method:

$self->{statefile_value} = centreon::plugins::statefile->new(%options);
$self->{statefile_value}->check_options(%options);
$self->{statefile_value}->read(statefile => 'my_cache_file',
                               statefile_dir => '/var/lib/centreon/centplugins'
                              );

my $new_datas = {};
$new_datas->{last_timestamp} = time();
$self->{statefile_value}->write(data => $new_datas);

Then, you can read the result in ‘/var/lib/centreon/centplugins/my_cache_file’, timestamp is written in it.

HTTP

This library provides a set of methodss to use HTTP protocol. To use it, add the following line at the beginning of your mode:

use centreon::plugins::http;

Some options must be set in plugin.pm:

Option Type Description
hostname String IP Addr/FQDN of the webserver host.
port String HTTP port.
proto String Used protocol (‘http’ or ‘https’).
credentials   Use credentials.
ntlm   Use NTLM authentication (if --credentials is used).
username String Username (if --credentials is used).
password String User password (if --credentials is used).
proxyurl String Proxy to use.
url_path String URL to connect (start to ‘/’).

connect

Description

Test a connection to an HTTP url. Return content of the webpage.

Parameters

This method use plugin options previously defined.

Example

This is an example of how to use connect method. We suppose these options are defined : * –hostname = ‘google.com’ * –urlpath = ‘/’ * –proto = ‘http’ * –port = 80

$self->{http} = centreon::plugins::http->new(output => $self->{output});
$self->{http}->set_options(%{$self->{option_results}});
my $webcontent = $self->{http}->request();
print $webcontent;

Output displays content of the webpage ‘http://google.com/’.

DBI

This library allows you to connect to databases. To use it, add the following line at the beginning of your plugin.pm:

use base qw(centreon::plugins::script_sql);

connect

Description

Connect to databases.

Parameters

Parameter Type Default Description
dontquit Int (0 or 1) 0 Don’t quit even if errors occured.

Example

This is an example of how to use connect method. The format of the connection string can have the following forms:

DriverName:database_name
DriverName:database_name@hostname:port
DriverName:database=database_name;host=hostname;port=port

In plugin.pm:

$self->{sqldefault}->{dbi} = ();
$self->{sqldefault}->{dbi} = { data_source => 'mysql:host=127.0.0.1;port=3306' };

In your mode:

$self->{sql} = $options{sql};
my ($exit, $msg_error) = $self->{sql}->connect(dontquit => 1);

Then, you are connected to the MySQL database.

query

Description

Send query to database.

Parameters

Parameter Type Default Description
query String   SQL query to send.

Example

This is an example of how to use query method:

$self->{sql}->query(query => q{SHOW /*!50000 global */ STATUS LIKE 'Slow_queries'});
my ($name, $result) = $self->{sql}->fetchrow_array();

print 'Name : '.$name."\n";
print 'Value : '.$value."\n";

Output displays count of MySQL slow queries.

fetchrow_array

Description

Return Array from sql query.

Parameters

None.

Example

This is an example of how to use fetchrow_array method:

$self->{sql}->query(query => q{SHOW /*!50000 global */ STATUS LIKE 'Uptime'});
my ($dummy, $result) = $self->{sql}->fetchrow_array();

print 'Uptime : '.$result."\n";

Output displays MySQL uptime.

fetchall_arrayref

Description

Return Array from SQL query.

Parameters

None.

Example

This is an example of how to use fetchrow_array method:

$self->{sql}->query(query => q{
      SELECT SUM(DECODE(name, 'physical reads', value, 0)),
          SUM(DECODE(name, 'physical reads direct', value, 0)),
          SUM(DECODE(name, 'physical reads direct (lob)', value, 0)),
          SUM(DECODE(name, 'session logical reads', value, 0))
      FROM sys.v_$sysstat
});
my $result = $self->{sql}->fetchall_arrayref();

my $physical_reads = @$result[0]->[0];
my $physical_reads_direct = @$result[0]->[1];
my $physical_reads_direct_lob = @$result[0]->[2];
my $session_logical_reads = @$result[0]->[3];

print $physical_reads."\n";

Output displays physical reads on Oracle database.

fetchrow_hashref

Description

Return Hash table from SQL query.

Parameters

None.

Example

This is an example of how to use fetchrow_hashref method:

$self->{sql}->query(query => q{
  SELECT datname FROM pg_database
});

while ((my $row = $self->{sql}->fetchrow_hashref())) {
  print $row->{datname}."\n";
}

Output displays Postgres databases.

Complete examples

Simple SNMP request

Description

This example explains how to check a single SNMP value on a PfSense firewall (memory dropped packets).
We use cache file because it’s a SNMP counter. So we need to get the value between 2 checks.
We get the value and compare it to warning and critical thresholds.

Plugin file

First, create the plugin directory and the plugin file:

$ mkdir -p apps/pfsense/snmp
$ touch apps/pfsense/snmp/plugin.pm

Tip

PfSense is a firewall application and we check it using SNMP protocol

Then, edit plugin.pm and add the following lines:

################################################################################
# Copyright 2005-2015 MERETHIS
# Centreon is developped by : Julien Mathis and Romain Le Merlus under
# GPL Licence 2.0.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation ; either version 2 of the License.
#
# This program is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
# PARTICULAR PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, see <http://www.gnu.org/licenses>.
#
# Linking this program statically or dynamically with other modules is making a
# combined work based on this program. Thus, the terms and conditions of the GNU
# General Public License cover the whole combination.
#
# As a special exception, the copyright holders of this program give MERETHIS
# permission to link this program with independent modules to produce an executable,
# regardless of the license terms of these independent modules, and to copy and
# distribute the resulting executable under terms of MERETHIS choice, provided that
# MERETHIS also meet, for each linked independent module, the terms  and conditions
# of the license of that module. An independent module is a module which is not
# derived from this program. If you modify this program, you may extend this
# exception to your version of the program, but you are not obliged to do so. If you
# do not wish to do so, delete this exception statement from your version.
#
# For more information : contact@centreon.com
# Authors : your name <your@mail>
#
####################################################################################

# Path to the plugin
package apps::pfsense::snmp::plugin;

# Needed libraries
use strict;
use warnings;
# Use this library to check using SNMP protocol
use base qw(centreon::plugins::script_snmp);

Tip

Don’t forget to edit ‘Authors’ line.

Add new method to instantiate the plugin:

sub new {
  my ($class, %options) = @_;
  my $self = $class->SUPER::new(package => __PACKAGE__, %options);
  bless $self, $class;
  # $options->{options} = options object

  # Plugin version
  $self->{version} = '0.1';

  # Modes association
  %{$self->{modes}} = (
                       # Mode name => path to the mode
                       'memory-dropped-packets'   => 'apps::pfsense::snmp::mode::memorydroppedpackets',
                       );

  return $self;
}

Declare this plugin as a perl module:

1;

Add a description to the plugin:

__END__

=head1 PLUGIN DESCRIPTION

Check pfSense in SNMP.

=cut

Tip

This description is printed with ‘–help’ option.

Mode file

Then, create the mode directory and the mode file:

$ mkdir apps/pfsense/snmp/mode
$ touch apps/pfsense/snmp/mode/memorydroppedpackets.pm

Edit memorydroppedpackets.pm and add the following lines:

################################################################################
# Copyright 2005-2015 MERETHIS
# Centreon is developped by : Julien Mathis and Romain Le Merlus under
# GPL Licence 2.0.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation ; either version 2 of the License.
#
# This program is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
# PARTICULAR PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, see <http://www.gnu.org/licenses>.
#
# Linking this program statically or dynamically with other modules is making a
# combined work based on this program. Thus, the terms and conditions of the GNU
# General Public License cover the whole combination.
#
# As a special exception, the copyright holders of this program give MERETHIS
# permission to link this program with independent modules to produce an executable,
# regardless of the license terms of these independent modules, and to copy and
# distribute the resulting executable under terms of MERETHIS choice, provided that
# MERETHIS also meet, for each linked independent module, the terms  and conditions
# of the license of that module. An independent module is a module which is not
# derived from this program. If you modify this program, you may extend this
# exception to your version of the program, but you are not obliged to do so. If you
# do not wish to do so, delete this exception statement from your version.
#
# For more information : contact@centreon.com
# Authors : your name <your@mail>
#
####################################################################################

# Path to the plugin
package apps::pfsense::snmp::mode::memorydroppedpackets;

# Needed library for modes
use base qw(centreon::plugins::mode);

# Needed libraries
use strict;
use warnings;

# Custom library
use POSIX;

# Needed library to use cache file
use centreon::plugins::statefile;

Add new method to instantiate the mode:

sub new {
  my ($class, %options) = @_;
  my $self = $class->SUPER::new(package => __PACKAGE__, %options);
  bless $self, $class;

  # Mode version
  $self->{version} = '1.0';

  # Declare options
  $options{options}->add_options(arguments =>
                              {
                                # option name        => variable name
                                "warning:s"          => { name => 'warning', },
                                "critical:s"         => { name => 'critical', },
                              });

  # Instantiate cache file
  $self->{statefile_value} = centreon::plugins::statefile->new(%options);
  return $self;
}

Tip

A default value can be added to options. Example : “warning:s” => { name => ‘warning’, default => ‘80’},

Add check_options method to validate options:

sub check_options {
  my ($self, %options) = @_;
  $self->SUPER::init(%options);

  # Validate threshold options with threshold_validate method
  if (($self->{perfdata}->threshold_validate(label => 'warning', value => $self->{option_results}->{warning})) == 0) {
     $self->{output}->add_option_msg(short_msg => "Wrong warning threshold '" . $self->{option_results}->{warning} . "'.");
     $self->{output}->option_exit();
  }
  if (($self->{perfdata}->threshold_validate(label => 'critical', value => $self->{option_results}->{critical})) == 0) {
     $self->{output}->add_option_msg(short_msg => "Wrong critical threshold '" . $self->{option_results}->{critical} . "'.");
     $self->{output}->option_exit();
  }

  # Validate cache file options using check_options method of statefile library
  $self->{statefile_value}->check_options(%options);
}

Add run method to execute mode:

sub run {
  my ($self, %options) = @_;
  # $options{snmp} = snmp object

  # Get SNMP options
  $self->{snmp} = $options{snmp};
  $self->{hostname} = $self->{snmp}->get_hostname();
  $self->{snmp_port} = $self->{snmp}->get_port();

  # SNMP oid to request
  my $oid_pfsenseMemDropPackets = '.1.3.6.1.4.1.12325.1.200.1.2.6.0';
  my ($result, $value);

  # Get SNMP value for oid previsouly defined
  $result = $self->{snmp}->get_leef(oids => [ $oid_pfsenseMemDropPackets ], nothing_quit => 1);
  # $result is a hash table where keys are oids
  $value = $result->{$oid_pfsenseMemDropPackets};

  # Read the cache file
  $self->{statefile_value}->read(statefile => 'pfsense_' . $self->{hostname}  . '_' . $self->{snmp_port} . '_' . $self->{mode});
  # Get cache file values
  my $old_timestamp = $self->{statefile_value}->get(name => 'last_timestamp');
  my $old_memDropPackets = $self->{statefile_value}->get(name => 'memDropPackets');

  # Create a hash table with new values that will be write to cache file
  my $new_datas = {};
  $new_datas->{last_timestamp} = time();
  $new_datas->{memDropPackets} = $value;

  # Write new values to cache file
  $self->{statefile_value}->write(data => $new_datas);

  # If cache file didn't have any values, create it and wait another check to calculate value
  if (!defined($old_timestamp) || !defined($old_memDropPackets)) {
      $self->{output}->output_add(severity => 'OK',
                                  short_msg => "Buffer creation...");
      $self->{output}->display();
      $self->{output}->exit();
  }

  # Fix when PfSense reboot (snmp counters initialize to 0)
  $old_memDropPackets = 0 if ($old_memDropPackets > $new_datas->{memDropPackets});

  # Calculate time between 2 checks
  my $delta_time = $new_datas->{last_timestamp} - $old_timestamp;
  $delta_time = 1 if ($delta_time == 0);

  # Calculate value per second
  my $memDropPacketsPerSec = ($new_datas->{memDropPackets} - $old_memDropPackets) / $delta_time;

  # Calculate exit code by comparing value to thresholds
  # Exit code can be : 'OK', 'WARNING', 'CRITICAL', 'UNKNOWN'
  my $exit_code = $self->{perfdata}->threshold_check(value => $memDropPacketsPerSec,
                                                     threshold => [ { label => 'critical', 'exit_litteral' => 'critical' }, { label => 'warning', exit_litteral => 'warning' } ]);

  # Add a performance data
  $self->{output}->perfdata_add(label => 'dropped_packets_Per_Sec',
                                value => sprintf("%.2f", $memDropPacketsPerSec),
                                warning => $self->{perfdata}->get_perfdata_for_output(label => 'warning'),
                                critical => $self->{perfdata}->get_perfdata_for_output(label => 'critical'),
                                min => 0);

  # Add output
  $self->{output}->output_add(severity => $exit_code,
                              short_msg => sprintf("Dropped packets due to memory limitations : %.2f /s",
                                  $memDropPacketsPerSec));

  # Display output
  $self->{output}->display();
  $self->{output}->exit();
}

Declare this plugin as a perl module:

1;

Add a description of the mode options:

__END__

=head1 MODE

Check number of packets per second dropped due to memory limitations.

=over 8

=item B<--warning>

Threshold warning for dropped packets in packets per second.

=item B<--critical>

Threshold critical for dropped packets in packets per second.

=back

=cut

Command line

This is an example of command line:

$ perl centreon_plugins.pl --plugin apps::pfsense::snmp::plugin --mode memory-dropped-packets --hostname 192.168.0.1 --snmp-community 'public' --snmp-version '2c' --warning '1' --critical '2'

Output may display:

OK: Dropped packets due to memory limitations : 0.00 /s | dropped_packets_Per_Sec=0.00;0;;1;2