Configuration de Nagios

Written by Sebastien Lambot on 03/01/2013. Posted in Articles techniques, Réseaux

Nagios est installé, il ne reste plus qu’à le configurer. Voici comment monitorer une infra simple en créant quelques fichiers de configuration.

Pour vérifier votre configuration de Nagios, vous pouvez exécuter la commande

# /usr/local/bin/nagios -v /usr/local/etc/nagios/nagios.cfg

Et pour redémarrer Nagios afin qu’il prenne en compte les dernières versions des fichiers de config

# service nagios restart

Configuration de Nagios

Afin d’avoir une structure un peu hiérarchisée au niveau des machines à surveiller, on peut éditer le fichier nagios.cfg et y ajouter

cfg_dir=/usr/local/etc/nagios/objects

afin que tous les fichiers .cfg contenus dans /usr/local/etc/nagios/objects soient ajoutés.

Dans ce directory « objects », on doit retrouver pour l’instant les fichiers

commands.cfg
contacts.cfg
timeperiods.cfg

ainsi que les templates et le fichier de config du localhost

generic-host.cfg
generic-service.cfg
generic-contact.cfg
localhost.cfg

Afficher: generic-host.cfg	Select Afficher
# All default values are set by this generic-host template define host{ name generic-host initial_state o active_checks_enabled 1 passive_checks_enabled 1 notifications_enabled 1 event_handler_enabled 0 check_command check-host-alive flap_detection_enabled 1 failure_prediction_enabled 1 failure_prediction_options d,u,r process_perf_data 1 check_freshness 0 obsess_over_host 0 check_period 24x7 check_interval 0 retry_interval 1 stalking_options u,d max_check_attempts 10 retain_status_information 1 retain_nonstatus_information 1 notification_period 24x7 first_notification_delay 0 contact_groups admins notification_options d,u,r notification_interval 0 register 0 notes generic-host }

Afficher: generic-host.cfg

# All default values are set by this generic-host template

define host{
        name                            generic-host
        initial_state                   o
        active_checks_enabled           1
        passive_checks_enabled          1
        notifications_enabled           1
        event_handler_enabled           0
        check_command                   check-host-alive
        flap_detection_enabled          1
        failure_prediction_enabled      1
        failure_prediction_options      d,u,r
        process_perf_data               1
        check_freshness                 0
        obsess_over_host                0
        check_period                    24x7
        check_interval                  0
        retry_interval                  1
        stalking_options                u,d
        max_check_attempts              10
        retain_status_information       1
        retain_nonstatus_information    1
        notification_period             24x7
        first_notification_delay        0
        contact_groups                  admins
        notification_options            d,u,r
        notification_interval           0
        register                        0
        notes                           generic-host
        }

Afficher: generic-service.cfg	Select Afficher
# All default values are set by this generic-host template define service{ name generic-service active_checks_enabled 1 passive_checks_enabled 1 initial_state o parallelize_check 1 obsess_over_service 0 check_freshness 0 notifications_enabled 1 event_handler_enabled 0 flap_detection_enabled 1 failure_prediction_enabled 1 failure_prediction_options w,c,u process_perf_data 1 retain_status_information 1 retain_nonstatus_information 1 is_volatile 0 check_period 24x7 flap_detection_options o,u,c,w max_check_attempts 5 normal_check_interval 5 retry_check_interval 2 contact_groups admins notification_options w,u,c,r notification_interval 0 notification_period 24x7 first_notification_delay 0 notes generic-service register 0 }

Afficher: generic-service.cfg

# All default values are set by this generic-host template

define service{
        name                            generic-service
        active_checks_enabled           1
        passive_checks_enabled          1
        initial_state                   o
        parallelize_check               1
        obsess_over_service             0
        check_freshness                 0
        notifications_enabled           1
        event_handler_enabled           0
        flap_detection_enabled          1
        failure_prediction_enabled      1
        failure_prediction_options      w,c,u
        process_perf_data               1
        retain_status_information       1
        retain_nonstatus_information    1
        is_volatile                     0
        check_period                    24x7
        flap_detection_options          o,u,c,w
        max_check_attempts              5
        normal_check_interval           5
        retry_check_interval            2
        contact_groups                  admins
        notification_options            w,u,c,r
        notification_interval           0
        notification_period             24x7
        first_notification_delay        0
        notes                           generic-service
        register                        0
        }

Afficher: generic-contact.cfg	Select Afficher
define contact{ name generic-contact service_notification_period 24x7 host_notification_period 24x7 service_notification_options w,u,c,r,f,s host_notification_options d,u,r,f,s service_notification_commands notify-service-by-email host_notification_commands notify-host-by-email register 0 }

Afficher: generic-contact.cfg

define contact{
        name                            generic-contact
        service_notification_period     24x7
        host_notification_period        24x7
        service_notification_options    w,u,c,r,f,s
        host_notification_options       d,u,r,f,s
        service_notification_commands   notify-service-by-email
        host_notification_commands      notify-host-by-email
        register                        0
        }

Afficher: localhost.cfg	Select Afficher
# HOST DEFINITION # Define a host for the local machine define host{ use generic-host host_name localhost alias localhost address 127.0.0.1 } # SERVICE DEFINITIONS # Define a service to "ping" the local machine define service{ use generic-service host_name localhost service_description PING check_command check_ping!100.0,20%!500.0,60% } # Define a service to check the disk space of the root partition # on the local machine. Warning if < 20% free, critical if # < 10% free space on partition. define service{ use generic-service host_name localhost service_description Root Partition check_command check_local_disk!20%!10%!/ } # Define a service to check the number of currently logged in # users on the local machine. Warning if > 20 users, critical # if > 50 users. define service{ use generic-service host_name localhost service_description Current Users check_command check_local_users!20!50 } # Define a service to check the number of currently running procs # on the local machine. Warning if > 250 processes, critical if # > 400 users. define service{ use generic-service host_name localhost service_description Total Processes check_command check_local_procs!250!400!RSZDT } # Define a service to check the load on the local machine. define service{ use generic-service host_name localhost service_description Current Load check_command check_local_load!5.0,4.0,3.0!10.0,6.0,4.0 } # Define a service to check the swap usage the local machine. # Critical if less than 10% of swap is free, warning if less than 20% is free define service{ use generic-service host_name localhost service_description Swap Usage check_command check_local_swap!20!10 } # Define a service to check SSH on the local machine. # Disable notifications for this service by default, as not all users may have SSH enabled. define service{ use generic-service host_name localhost service_description SSH check_command check_ssh notifications_enabled 0 } # Define a service to check HTTP on the local machine. # Disable notifications for this service by default, as not all users may have HTTP enabled. define service{ use generic-service host_name localhost service_description HTTP check_command check_http notifications_enabled 0 }

Afficher: localhost.cfg

# HOST DEFINITION
# Define a host for the local machine

define host{
        use                     generic-host
        host_name               localhost
        alias                   localhost
        address                 127.0.0.1
        }

# SERVICE DEFINITIONS
# Define a service to "ping" the local machine

define service{
        use                             generic-service
        host_name                       localhost
        service_description             PING
        check_command                   check_ping!100.0,20%!500.0,60%
        }

# Define a service to check the disk space of the root partition
# on the local machine.  Warning if < 20% free, critical if
# < 10% free space on partition.

define service{
        use                             generic-service
        host_name                       localhost
        service_description             Root Partition
        check_command                   check_local_disk!20%!10%!/
        }

# Define a service to check the number of currently logged in
# users on the local machine.  Warning if > 20 users, critical
# if > 50 users.

define service{
        use                             generic-service
        host_name                       localhost
        service_description             Current Users
        check_command                   check_local_users!20!50
        }

# Define a service to check the number of currently running procs
# on the local machine.  Warning if > 250 processes, critical if
# > 400 users.

define service{
        use                             generic-service
        host_name                       localhost
        service_description             Total Processes
        check_command                   check_local_procs!250!400!RSZDT
        }

# Define a service to check the load on the local machine.

define service{
        use                             generic-service
        host_name                       localhost
        service_description             Current Load
        check_command                   check_local_load!5.0,4.0,3.0!10.0,6.0,4.0
        }

# Define a service to check the swap usage the local machine.
# Critical if less than 10% of swap is free, warning if less than 20% is free

define service{
        use                             generic-service
        host_name                       localhost
        service_description             Swap Usage
        check_command                   check_local_swap!20!10
        }

# Define a service to check SSH on the local machine.
# Disable notifications for this service by default, as not all users may have SSH enabled.

define service{
        use                             generic-service
        host_name                       localhost
        service_description             SSH
        check_command                   check_ssh
        notifications_enabled           0
        }

# Define a service to check HTTP on the local machine.
# Disable notifications for this service by default, as not all users may have HTTP enabled.

define service{
        use                             generic-service
        host_name                       localhost
        service_description             HTTP
        check_command                   check_http
        notifications_enabled           0
        }

Création d’un host

Dans le directory objects, on crée le fichier de config gandalf.cfg qui définit notre premier host (en utilisant notre template generic-host et en remplaçant les « x » par l’adresse IP)

define host{
        use                     generic-host
        host_name               gandalf
        alias                   Gandalf
        address                 xx.xx.xx.xx
        }

Si vous préférez utiliser la résolution DNS plutôt que de spécifier une adresse IP, vous pouvez supprimer la ligne « address ».

Après un redémarrage, le nouveau host apparaît dans les hosts de Nagios.

hosts

Ajout de services pour notre nouveau host

Pour créer des services pour un host, on ajoute simplement la liste des services et leurs paramètres à son fichier de config

# Definition du service de Load Average
define service{
        use                             generic-service
        host_name                       gandalf
        service_description             Load Average
        check_command                   check_load!5.0,4.0,3.0!10.0,8.0,6.0
        }

# Definition du service de controle d'url Web
define service{
        use                             generic-service
        host_name                       gandalf
        service_description             Reponse interface Web
        check_command                   check_http!"http://gandalf"
        notifications_enabled           0
        }

La commande check_load n’étant pas connue (erreur lors de la vérification des fichiers), il faut la définir en l’ajoutant au fichier commands.cfg

# 'check_load' command definition
define command{
        command_name    check_load
        command_line    $USER1$/check_load -w $ARG1$ -c $ARG2$
        }

Après un redémarrage de Nagios, l’affichage des services devrait ressembler à ceci

services

Création d’un contact

On édite le fichier contacts.cfg et on y ajoute un contact et son groupe

define contact{
        contact_name                    jsmith
        use                             generic-contact
        alias                           John Smith
        email                           j.smith@company.be
        }
define contactgroup{
        contactgroup_name       support
        alias                   Support Technique
        members                 jsmith
        }

Pour que le groupe Support Technique soit alerté, il faut ajouter le paramètre suivant dans le fichier de config du host (ou dans le template correspondant), soit dans la définition de l’host lui-même, soit dans la définition du service concerné (il faut que le paramètre notifications_enabled soit à 1).

contact_groups           support

Si la notification par email est correctement configurée, un mail sera envoyé au déclenchement d’une alerte.

Tags: nagios

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Configuration de Nagios

Création d’un host

Ajout de services pour notre nouveau host

Création d’un contact

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