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Version: 22.10

Les commandes

Définition​

Une commande est la définition d’une ligne de commande qui utilise un script ou une application afin de réaliser une action. Il est possible d’exécuter cette commande en précisant des arguments.

Il existe quatre types de commandes :

  • Verification sont utilisées par les ordonnanceurs afin de vérifier le statut d’un hôte ou d’un service
  • Notification sont utilisées par les ordonnanceurs pour alerter les contacts (via mail, SMS...).
  • Discovery sont utilisées par les règles de découverte.
  • Miscellaneous sont utilisées par les modules complémentaires (pour effectuer certaines actions), par l’ordonnanceur pour le traitement des données...

Toutes les commandes peuvent être configurées au sein du menu : Configuration > Commands.

image

Par défaut, les commandes verrouillées sont masquées. Cocher la case "Eléments verrouillés" pour les afficher toutes.

Ajouter une commande​

  1. Rendez-vous dans le menu Configuration > Commands
  2. Cliquez sur le bouton Add

image

Les champs de configuration d’une commande sont les mêmes qu’importe le type de commande choisi.

Les champs de configuration​

  • Le champ command Name définit le nom de la commande.

  • Le champ Command Type permet de choisir le type de commande.

  • Le champ Command Line indique l’application ou le script utilisé avec la commande.

  • La case Enable shell permet d’activer des fonctions propres à un shell tel que le pipe...

  • Le champ Argument Example définir des exemples d'arguments (chaque argument commence par un "!")

  • Le bouton Describe arguments permet d’ajouter une description aux arguments de type “$ARGn$”. Cette description sera visible lors de l’utilisation de la commande dans un formulaire d’hôte ou de service.

  • Le bouton Clear arguments efface la description des arguments définie

  • Le bouton Describe macros permet d’ajouter une description aux macros personalisées. Ces descriptions seront visibles lors de l’ajout de la commande sur un host ou un service.

  • La liste de sélection Connectors permet de lier un connecteur à la commande. Pour davantage d’informations sur les connecteurs reportez-vous au chapitre les connecteurs.

  • Le champ Graph template permet de lier la commande à un modèle de graphique.

  • Le champ Comment permet de commenter la commande.

Arguments et macros​

Au sein du champ Command Line il est possible de faire appel à des macros ainsi qu’à des arguments.

Les arguments sont utilisés afin de pouvoir passer différents paramètres aux scripts appelés par les commandes. Lors de l’exécution de la commande par l’ordonnanceur, chacun des arguments et macros sont remplacés par leur valeur respective. Chaque macro se présente sous la forme $valeur$ :

$CENTREONPLUGINS$/centreon_linux_snmp.pl --plugin=os::linux::snmp::plugin --mode=cpu \
--hostname=$HOSTADDRESS$ --snmp-version='$_HOSTSNMPVERSION$' \
--snmp-community='$_HOSTSNMPCOMMUNITY$' $_HOSTSNMPEXTRAOPTIONS$ \
--warning-average='$_SERVICEWARNING$' \
--critical-average='$_SERVICECRITICAL$' $_SERVICEEXTRAOPTIONS$

La bonne pratique veut que nous remplacions les arguments par des macros personnalisées.

Les connecteurs​

Ce chapitre technique n'est disponible qu'en langue anglaise

SSH connectors​

Centreon SSH Connector is a free software from Centreon available under the Apache Software License version 2 (ASL 2.0). It speeds up execution checks over SSH when used along Centreon Engine.

Installation​

Centreon recommends using its official packages. Most of Centreon’ endorsed software are available as RPM packages.

Run the following commands as privileged user:

yum install centreon-connector-ssh

Or you can build the Centreon SSH Connector. You will need the following external dependencies:

  • a C++ compilation environment.
  • CMake (>= 2.8), a cross-platform build system.
  • Centreon Clib, The centreon Core library.
  • ssh2 library to use ssh functions.
  • gcrypt library to secure connections.

This program is compatible only with Unix-like platforms (Linux, FreeBSD, Solaris, ...).

Prerequisites​

In CentOS you need to add manually cmake. After that you can install binary packages. Either use the Package Manager or the yum tool to install them. You should check packages version when necessary.

Package required to build:

SoftwarePackage NameDescription
C++ compilation environmentgcc gcc-c++ makeMandatory tools to compile.
CMake (>= 2.8)cmakeRead the build script and prepare sources for compilation.
Centreon Clib (>= 1.0)centreon-clib-develCore library used by Centreon Connector.
ssh2 librarylibssh2-develSSH library.
gcrypt librarylibgcrypt-develGcrypt library.
  1. Install basic compilation tools
yum install gcc gcc-c++ make libssh2-devel libgcrypt-devel
  1. Install cmake
yum install cmake
  1. Install Centreon Clib

See the Centreon Clib @TODO@:ref:documentation <centreon-clib:centreon_clib_install>.

Build​
Get sources​

Centreon SSH Connector can be checked out from GitHub. The SSH connector sources reside in the ssh subdirectory. On a Linux box with git installed this is just a matter of:

git clone https://github.com/centreon/centreon-connectors
Configuration​

At the root of the project directory you'll find a ssh/build directory which holds build scripts. Generate the Makefile by running the following command:

cd /path_to_centreon_connector/ssh/build

Your Centreon SSH Connector can be tweaked to your particular needs using CMake's variable system. Variables can be set like this:

cmake -D<variable1>=<value1> [-D<variable2>=<value2>] .

Here's the list of variables available and their description:

VariableDescriptionDefault value
WITH_CENTREON_CLIB_INCLUDE_DIRSet the directory path of centreon-clib include.auto detection
WITH_CENTREON_CLIB_LIBRARIESSet the centreon-clib library to use.auto detection
WITH_CENTREON_CLIB_LIBRARY_DIRSet the centreon-clib library directory (don't use it if you use WITH_CENTREON_CLIB_LIBRARIES)auto detection
WITH_KNOWN_HOSTS_CHECKEnable or disable Check hosts against user's known_hosts file.OFF
WITH_LIBGCRYPT_INCLUDE_DIRSet the directory path of libgcrypt include.auto detection
WITH_LIBGCRYPT_LIBRARIESSet the libgcrypt library to use.auto detection
WITH_LIBGCRYPT_LIBRARY_DIRSet the libgcrypt library directory (don't use it if you use WITH_LIBGCRYPT_LIBRARIES)auto detection
WITH_LIBSSH2_INCLUDE_DIRSet the directory path of libssh2 include.auto detection
WITH_LIBSSH2_LIBRARIESSet the libssh2 library to use.auto detection
WITH_LIBSSH2_LIBRARY_DIRSet the libssh2 library directory (don't use it if you use WITH_LIBSSH2_LIBRARIES)auto detection
WITH_PREFIXBase directory for Centreon SSH Connector installation. If other prefixes are expressed as relative paths, they are relative to this path./usr/local
WITH_PREFIX_BINARYDefine specific directory for Centreon Connector SSH binary.${WITH_PREFIX}/bin
WITH_TESTINGEnable generation of unit tests. They can later be run by typing make test. OFF

Example:

cmake \
    -DWITH_PREFIX=/usr \
    -DWITH_PREFIX_BINARY=/usr/lib/centreon-connector \
    -DWITH_TESTING=0 .

At this step, the software will check for existence and usability of the rerequisites. If one cannot be found, an appropriate error message will be printed. Otherwise an installation summary will be printed.

If you need to change the options you used to compile your software, you might want to remove the CMakeCache.txt file that is in the build directory. This will remove cache entries that might have been computed during the last configuration step.

Compilation​

Once properly configured, the compilation process is really simple:

make

And wait until compilation completes.

Install​

Once compiled, the following command must be run as privileged user to finish installation:

make install

And wait for its completion.

Configuration​

Centreon SSH Connector itself does not require any configuration. It should only be configured as a connector of Centreon Engine.

To execute SSH check over SSH with Centreon SSH Connector from Centreon Engine, one might configure commands that relates to SSH check (like check_by_ssh).

Binary arguments​

Here are the supported arguments for centreon_connector_ssh:

Short nameLong nameDescription
-d--debugIf this flag is specified, print all logs messages.
-h--helpPrint help and exit.
-v--versionPrint software version and exit.
-l--log-fileSpecifies the log file (default: stderr).
-2--proto2Tell ssh to use Protocol 2.
-4--use-ipv4Enable IPv4 connection.
-6--use-ipv6Enable IPv6 connection.
-a--authenticationAuthentication password.
-C--commandCommand to execute on the remote machine.
-E--skip-stderrIgnore all or first n lines on STDERR.
-H--hostnameHost name, IP Address.
-i--identityIdentity of an authorized key.
-l--lognameSSH user name on remote host.
-p--portPort number (default: 22)
-S--skip-stdoutIgnore all or first n lines on STDOUT.
-t--timeoutSeconds before connection times out (default: 10).
Check arguments​

These arguments are checks options (like check_by_ssh options).

Short nameLong nameDescription
-1--proto1This option is not supported.
-2--proto2Tell ssh to use Protocol 2.
-4--use-ipv4Enable IPv4 connection.
-6--use-ipv6Enable IPv6 connection.
-a--authenticationAuthentication password.
-C--commandCommand to execute on the remote machine.
-E--skip-stderrIgnore all or first n lines on STDERR.
-f--forkThis option is not supported.
-h--helpNot used.
-H--hostnameHost name, IP Address.
-i--identityIdentity of an authorized key.
-l--lognameSSH user name on remote host.
-n--nameThis option is not supported.
-o--ssh-optionThis option is not supported.
-O--outputThis option is not supported.
-p--portPort number (default 22).
-q--quietNot used.
-s--servicesThis option is not supported.
-S--skip-stdoutIgnore all or first n lines on STDOUT.
-t--timeoutSeconds before connection times out (default 10).
-v--verboseNot used.
-V--versionNot used.

Example:

define connector{
    connector_name centreon_connector_ssh
    connector_line /usr/lib64/centreon-connector/centreon_connector_ssh --log-file=/var/log/centreon-engine/centreon-connector-ssh.log
}

define command{
    command_name ssh_check_cpu
    command_line $USER1$/check_by_ssh -H $HOSTADDRESS$ -l $_HOSTUSER$ -a $_HOSTPASSWORD$ -C "$USER1$/check_cpu -w $ARG1$ -c $ARG2$"
    connector centreon_connector_ssh
}

define command{
    command_name ssh_check_disk
    command_line $USER1$/check_by_ssh -H $HOSTADDRESS$ -l $_HOSTUSER$ -a $_HOSTPASSWORD$ -C "$USER1$/check_disk -D $ARG1$ -w $ARG2$ -c $ARG3$"
    connector centreon_connector_ssh
}
Technical details​

This article describes how Centreon SSH Connector allow much gain on SSH check execution.

One major CPU-intensive and long operation in a SSH environment is the key exchange and verification mechanism. This operation occurs when a SSH session is started between two hosts. After this step all exchange operations are using far less resources.

Centreon SSH Connector take advantage of this fact and maintain semi-permanent connection with hosts to which it had to connect to. This way if multiple checks are performed on the same host, where "check_by_ssh" opens one session for each check, Centreon Connector SSH only opens one session. However this does not limit the number of concurrent checks on a host, as the SSH protocol allows multiple channels to be opened on the same session. Therefore if multiple checks are run on the same host simultaneously, they are executed concurrently but with separate execution environment.

Perl connector​

Centreon Perl Connector is a free software from Centreon available under the Apache Software License version 2 (ASL 2.0). It speeds up execution of Perl scripts when used along Centreon Engine.

Installation​

Centreon recommends using its official packages. Most of Centreon’ endorsed software are available as RPM packages.

Run the following commands as privileged user:

yum install centreon-connector-perl

Or you can build the Centreon SSH Connector. You will need the following external dependencies:

  • a C++ compilation environment.
  • CMake (>= 2.8), a cross-platform build system.
  • Centreon Clib, The centreon Core library.
  • ssh2 library to use ssh functions.
  • gcrypt library to secure connections.

This program is compatible only with Unix-like platforms (Linux, FreeBSD, Solaris, ...).

Prerequisites​

In CentOS you need to add manually cmake. After that you can install binary packages. Either use the Package Manager or the yum tool to install them. You should check packages version when necessary.

Package required to build:

SoftwarePackage NameDescription
C++ compilation environmentgcc gcc-c++ makeMandatory tools to compile.
CMake (>= 2.8)cmakeRead the build script and prepare sources for compilation.
Centreon Clib (>= 1.0)centreon-clib-develCore library used by Centreon Connector.
PerlperlScripting language.
  1. Install basic compilation tools
yum install gcc gcc-c++ make perl
  1. Install cmake
yum install cmake
  1. Install Centreon Clib

See the Centreon Clib @TODO@:ref:documentation <centreon-clib:centreon_clib_install>.

Build​
Get sources​

Centreon Perl Connector can be checked out from GitHub. The Perl connector sources reside in the perl subdirectory. On a Linux box with git installed this is just a matter of:

git clone https://github.com/centreon/centreon-connectors
Configuration​

At the root of the project directory you'll find a perl/build directory which holds build scripts. Generate the Makefile by running the following command:

cd /path_to_centreon_connector/perl/build

Your Centreon Perl Connector can be tweaked to your particular needs using CMake's variable system. Variables can be set like this:

cmake -D<variable1>=<value1> [-D<variable2>=<value2>] .

Here's the list of variables available and their description:

VariableDescriptionDefault value
WITH_CENTREON_CLIB_INCLUDE_DIRSet the directory path of centreon-clib include.auto detection
WITH_CENTREON_CLIB_LIBRARIESSet the centreon-clib library to use.auto detection
WITH_CENTREON_CLIB_LIBRARY_DIRSet the centreon-clib library directory (don't use it if you use WITH_CENTREON_CLIB_LIBRARIES)auto detection
WITH_PREFIXBase directory for Centreon PErl Connector installation. If other prefixes are expressed as relative paths, they are relative to this path./usr/local
WITH_PREFIX_BINARYDefine specific directory for Centreon Connector Perl binary.${WITH_PREFIX}/bin
WITH_TESTINGEnable generation of unit tests. They can later be run by typing make test.OFF

Example:

cmake \
    -DWITH_PREFIX=/usr \
    -DWITH_PREFIX_BINARY=/usr/lib/centreon-connector \
    -DWITH_TESTING=0 .

At this step, the software will check for existence and usability of the rerequisites. If one cannot be found, an appropriate error message will be printed. Otherwise an installation summary will be printed.

If you need to change the options you used to compile your software, you might want to remove the CMakeCache.txt file that is in the build directory. This will remove cache entries that might have been computed during the last configuration step.

Compilation​

Once properly configured, the compilation process is really simple:

make

And wait until compilation completes.

Install​

Once compiled, the following command must be run as privileged user to finish installation:

make install

And wait for its completion.

Configuration​

Centreon Perl Connector itself does not require any configuration. It should only be configured as a connector of Centreon Engine.

To execute Perl scripts with Centreon Perl Connector from Centreon Engine, one might configure commands that relates to Perl scripts. Such commands must only contain the path to the Perl script to execute followed by its arguments, just like one would on the command line. To make it simple, you just have to add a connector property to your command definition.

Binary arguments​

Here are the supported arguments for centreon_connector_perl:

Short nameLong nameDescription
-d--debugIf this flag is specified, print all logs messages.
-h--helpPrint help and exit.
-v--versionPrint software version and exit.
-c--codeArgument is some Perl code that will be executed by the embedded interpreter.
-l--log-fileSpecifies the log file (default: stderr).

Example:

define connector{
    connector_name centreon_connector_perl
    connector_line /usr/lib64/centreon-connector/centreon_connector_perl --log-file=/var/log/centreon-engine/centreon-connector-perl.log
}

define command{
    command_name check_ping
    command_line $USER1$/check_ping.pl -H $HOSTADDRESS$
    connector centreon_connector_perl
}

define command{
    command_name check_disk
    command_line $USER1$/check_disk.pl -H $HOSTADDRESS$ -D $ARG1$
    connector centreon_connector_perl
}
Technical details​

This article describes how Centreon Perl Connector allow much gain on Perl script execution.

First of all let's examine how a Perl script is executed traditionnally by Centreon Engine.

  • Centreon Engine forks, creating a new separate process.
  • This new process executes the execve syscall to run the Perl interpreter. This step does not create a new process.
  • The Perl interpreter parse the Perl script.
  • Perl script get executed.

With Centreon Engine, the same script get executed multiple times but with different arguments. Therefore we took advantage of this fact to efficiently parse all the scripts once and get them executed. This was only possible because of the fork()ing system of Unix-like platform. If you read the reference page on Wikipedia you indeed remarked that once fork()ed the old and the new process are identical. Centreon Connector Perl's steps to execute scripts are as follow.

  • Centreon Engine creates a resident process of Centreon Connector Perl once
  • For all Perl scripts execution requests are forwarded to this process when requested to execute a script, Centreon Perl Connector checks if this script has already been parsed if not it parses it using the Embedded Perl interpreter.
  • Centreon Perl Connector forks itself.
  • The precompiled script gets executed

This way Perl scripts are only parsed once during the lifetime of the monitoring engine. This heavily relates to prepared statements in SQL.