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h1. Introduction

Nagios is a complete infrastructure monitoring solution.

[Get more details about Nagios.|http://www.nagios.org/]

The integration of Petals ESB and Nagios is based on getting information about the JVM. This is done using SNMP probes.
{info}Following examples are based on a Petals ESB topology composed of two nodes on the same host.{info}

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h1. Installation

h2. Nagios installation

The Nagios integration was experienced on a Linux distribution "Ubuntu Quantal Quetzal (12.10)", using the Sun/Oracle JVM v1.6.0.43

Nagios 3 is available through the default Ubuntu repository. So, just install the package "nagios3" using the standard way.

h2. Enabling the SNMP agents of the Petals ESB JVMs

{include:Enabling the SNMP agent of a Petals ESB JVM}

h1. Nagios configuration

h2. JVM host template

A best practice to monitor Java application is to create a template 'JVM host':
{code}
define host{
     use                 generic-host
        name                            jvm-host    ; The name of this host template
        notifications_enabled           1       ; Host notifications are enabled
        event_handler_enabled           1       ; Host event handler is enabled
        flap_detection_enabled          1       ; Flap detection is enabled
        failure_prediction_enabled      1       ; Failure prediction is enabled
        process_perf_data               1       ; Process performance data
        retain_status_information       1       ; Retain status information across program restarts
        retain_nonstatus_information    1       ; Retain non-status information across program restarts
        check_command                   check-host-alive
        max_check_attempts              10
        notification_interval           0
        notification_period             24x7
        notification_options            d,u,r
        contact_groups                  admins
        register                        0       ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL HOST, JUST A TEMPLATE!
# Specific attributes
    _snmpport             161     ; Listening port of the JVM SNMP agent
        }
{code}

h2. Nagios commands definition to interact with a SNMP agent

We recommand to define specific Nagios command to interact with the Java virtual machine MIB.

Interresting commands will be:
* jvm_heapused: to get the real heap memory used by the Petals ESB node,
* jvm_heapmaxused: to get the current allocated (commited) heap size. This value should be check against the heap max size at the JVM level to generate alarms.

{code}
# 'jvm_heapused' command definition
define command{
    command_name    jvm_heapused
    command_line    /usr/lib/nagios/plugins/check_snmp -H '$HOSTADDRESS$' -p '$_HOSTSNMPPORT$' -C '$ARG1$' -P '$ARG2$' -o 1.3.6.1.4.1.42.2.145.3.163.1.1.2.11.0 -w :'$ARG3$' -c :'$ARG4$' -l load
    }

# 'jvm_heapmaxused' command definition
define command{
    command_name    jvm_heapmaxused
    command_line    /usr/lib/nagios/plugins/check_snmp -H '$HOSTADDRESS$' -p '$_HOSTSNMPPORT$' -C '$ARG1$' -P '$ARG2$' -o 1.3.6.1.4.1.42.2.145.3.163.1.1.2.12.0 -w :'$ARG3$' -c :'$ARG4$' -l load
    }
{code}

h2. Petals ESB host template

A best practice to monitor Petals ESB nodes is to create a template 'Petals ESB host' that inherits from the 'JVM host':
{code}
define host{
        use                             jvm-host
        name                            petals-esb-host    ; The name of this host template
        register                        0       ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL HOST, JUST A TEMPLATE!

# Specific attributes
_snmpport 16161 ; Listening port of the JVM SNMP agent. Redefined because Petals is not started by 'root'
_jmxport 7700 ; Listening port of the Petals JMX agent
        }
{code}

h2. Defining your Petals ESB hosts

For each Petals ESB node of your Petals ESB topology, create an instance of the template 'petals-esb-host':
{code}
define host{
        use                     petals-esb-host            ; Name of host template to use
        host_name               petals-esb-node-1
        alias                   Petals ESB Node 1
        address                 127.0.0.1
# Specific attributes: Uncomment to specify a value different from the default one
# _snmpport 16161 ; Listening port of the JVM SNMP agent
# _jmxport 7700 ; Listening port of the Petals JMX agent
        }

define host{
        use                     petals-esb-host            ; Name of host template to use
        host_name               petals-esb-node-2
        alias                   Petals ESB Node 2
        address                 192.168.1.25
# Specific attributes: Uncomment to specify a value different from the default one
# _snmpport 16161 ; Listening port of the JVM SNMP agent
# _jmxport 7700 ; Listening port of the Petals JMX agent
        }
{code}

h2. Defining your Petals ESB topology as a Petals ESB host group

The Petals ESB topology can be considered as a Nagios host group composed of your Petals ESB nodes:
{code}
define hostgroup {
        hostgroup_name petals-esb
        alias           The ESB
        members         petals-esb-node-1, petals-esb-node-2
        }
{code}

h2. Petals ESB host services

We group all Petals ESB host services:
{code}
define servicegroup{
servicegroup_name petals-services
alias Petals ESB Services
}
{code}

A best practice to monitor Petals ESB nodes is to create a template of services to associate to each Petals ESB nodes:
{code}
# Define a service to check the disk space of the partitions
# Warning if < 20% free, critical if < 10% free space on partition.
# Adapt the last parameter of "check_disk" to check only the
# partitions where dynamic data (as log files, repository) are
# written by petals (/var/lib/petals-esb, /var/log/petals-esb).
# Probably two services will be required with different thresholds.
define service{
use generic-service
hostgroup_name petals-esb
service_description Disk Space
check_command check_disk!20%!10%!/var
servicegroups petals-services
}


# Define a service to check the load on the local machine.
define service{
use generic-service
hostgroup_name petals-esb
service_description Current Load
check_command check_load!5.0!4.0!3.0!10.0!6.0!4.0
servicegroups petals-services
}

# Define a service to check the heap memory used by Petals ESB node.
# Warning if > 85% configured max heap size, critical if 95% configured
# max heap size.
# Note: The value returned by the SNMP Get is a byte value. So, for
# a max heap size of 1Go:
# 85% => 912680550 bytes,
# and 95% => 1020054733 bytes
define service{
use generic-service
hostgroup_name petals-esb
service_description Current heap memory
check_command jvm_heapused!public!2c!912680550!1020054732
servicegroups petals-services
}

# Define a service to check the max (commited) heap memory used by Petals ESB node.
# Warning if > Warning if > 85% configured max heap size, critical if 95% configured
# max heap size.
# Note: The value returned by the SNMP Get is a byte value. So, for
# a max heap size of 1Go:
# 85% => 912680550 bytes,
# and 95% => 1020054733 bytes
define service{
use generic-service
hostgroup_name petals-esb
service_description Current commited heap memory size
check_command jvm_heapmaxused!public!2c!912680550!1020054732
servicegroups petals-services
}
{code}

h2. Restart Nagios

Restart your Nagios service to take into account the configuration:
{code}
sudo service nagios3 restart
{code}
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