Nagios Server Installation (on CentOS)
Download:
Nagios 3.0.2 (http://www.nagios.org/download/)
Nagios plugins 1.4.11
Pnp 0.3.3 (http://www.ederdrom.de/doku.php/nagios/pnp_en)
Before starting: Make sure you have; apache, mysql (or just the libraries), oracle client, freetds.
Installing Nagios
- Get the latest version of nagios and the plugins.
- Create a nagios user, a nagios group and a nagcmd group.
- Create the installation directory (ex. /usr/local/nagios) and change the owner to nagios:nagios.
- Add the apache user (or whatever user apache is running as) to the nagcmd group.
- Untar nagios.
- Run the configure script "./configure --prefix=/usr/loca/nagios –with-cgiurl=/nagios/cgi-bin --with-htmurl=/nagios/ --with-nagios-user=nagios --with-nagios-group=nagios –with-command-group=nagcmd".
- Run make.
- Run make install.
- Run make install-init.
- Run make install-commandmode.
- Run make install-config.
Configuring Nagios
- By default a lot of configuration information is contained in localhost.cfg, so this is where you can setup stuff like the times to be monitored or the contacts.
If you wish to split this stuff up, modify nagios.cfg set the various config files/directories you want to use.
cfg_file=/usr/local/nagios/etc/contacts.cfg
cfg_file=/usr/local/nagios/etc/hostgroups.cfg
cfg_file=/usr/local/nagios/etc/services.cfg
cfg_dir=/usr/local/nagios/etc/servers
cfg_dir=/usr/local/nagios/etc/switches
- In order to use custom commands or to modify the behavior of you need go into the commands.cfg.
ex.
define command{
command_name check_oracle
command_line $USER1$/check_oracle --tns $ARG1$
}
ex.
define command{
command_name check_mysql
command_line $USER1$/check_mysql -H $HOSTADDRESS$ -d $ARG1$ -u $ARG2$ -p $ARG3$
}
- Create your service definition templates.
The “register 0” means it's a template.
The “use” option means to inherit the properties from the service defined there.
For more information on the other options read the Nagios documentation.
ex.
# Generic service template
define service{
name generic-service-template
active_checks_enabled 1
passive_checks_enabled 1
parallelize_check 1
obsess_over_service 1
check_freshness 0
notifications_enabled 1
event_handler_enabled 1
flap_detection_enabled 1
failure_prediction_enabled 1
process_perf_data 1
retain_status_information 1
retain_nonstatus_information 1
is_volatile 0
register 0
}
ex.
# Local service template
define service{
name local-service-template
use generic-service-template
check_period 24x7
max_check_attempts 4
normal_check_interval 5
retry_check_interval 1
contact_groups admins
notification_options w,u,c,r
notification_interva 60
notification_period 24x7
register 0
}
- Create your host definition templates.
ex.
# Generic Host Template
define host{
name generichost-template
notifications_enabled 1
event_handler_enabled 1
flap_detection_enabled 1
failure_prediction_enabled 1
process_perf_data 1
retain_status_information 1
retain_nonstatus_information 1
notification_period 24x7
register 0
}
ex.
# Remote Host Template
define host{
name remotehost-template
use generichost-template
check_period 24x7
max_check_attempts 10
check_command check-host-alive
notification_period workhours
notification_interval 120
notification_options d,u,r
contact_groups admins
}
Configuring a remote host
- Create the hosts you wish to monitor.
You can either put them all in one configuration file or split them up and make a configuration file for every single machine.
Here's an example of a configuration file for one machine which contains all it's information.
ex.
# Host
define host{
use remotehost-template
host_name <host's name>
hostgroups <host's group>
parents <host's parent>
alias <host's description>
address <host's ip address>
}
# Host Extensions
define hostextinfo{
host_name <host's name>
icon_image <image file>
statusmap_image <image file>
}
#Services
#Check http
define service{
use local-service-template
host_name <host's name>
service_description HTTP
check_command check_http!80!5!10
# Check disk space of /
# Warning if < 10% free, Critical if < 5% free
define service{
use local-service-template
host_name <host's name>
service_description Root Partition
check_command check_by_ssh!22!"/usr/local/nagios/libexec/check_disk -w 10% -c 5% -p /"
}
# Check disk space of /boot
# Warning if < 10% free, Critical if < 5% free
define service{
use local-service-template
host_name <host's name>
service_description Boot Partition
check_command check_by_ssh!22!"/usr/local/nagios/libexec/check_disk -w 10% -c 5% -p /"
}
# Check load
# Warning if > 5/4/3 processes in wait , Critical if > 10/6/4 processes in wait
# Warning/Critical configured on remote host
define service{
use local-service-template
host_name <host's name>
service_description Current Load
check_command check_by_ssh!22!"/usr/local/nagios/libexec/check_load -w 5,4,3 -c 10,6,4"
}
Configuring Apache
- In order to use apache you need to tell it where the nagios cgi files are and what you want your document root to be.
ex.
ScriptAlias /nagios/cgi-bin /usr/local/nagios/sbin <Directory "/usr/local/nagios/sbin"> Options ExecCGI AllowOverride None Order allow,deny Allow from all AuthName "Nagios Access" AuthType Basic AuthUserFile /usr/local/nagios/etc/htpasswd.users Require valid-user </Directory> Alias /nagios /usr/local/nagios/share <Directory "/usr/local/nagios/share"> Options None AllowOverride None Order allow,deny Allow from all AuthName "Nagios Access" AuthType Basic AuthUserFile /usr/local/nagios/etc/htpasswd.users Require valid-user </Directory>
- Use htpasswd to create the authorized users file.
Installing Nagios Plugins
- Untar nagios-plugins.
- run the configure script "./configure".
- Run make.
- Run make install.
Install PnP (graphs)
- Install perl-HiRes:
yum install perl-Time-HiRes.i386
- Download and install rrdtool (http://dag.wieers.com/rpm/packages/rrdtool/)
rrdtool
perl-rrdtool
- Untar pnp.
- Run the configure script "./configure".
- Run make all.
- make install.
Configuring PnP
- In the pnp dir (ex. /usr/loca/nagios/etc/pnp) modify config.php so that it uses rrdtool and where it will dump the performance logs.
ex.
$conf['rrdtool'] = "/usr/bin/rrdtool" $conf['rrdbase'] = "/usr/local/nagios/share/perfdata/"
- In the nagios.cfg modify the config so that it knows how to process the performance data.
This will cause the perfomance info to be updated every 30 seconds to reduce the load on the machine
ex.
process_performance_data=1 service_perfdata_file=/usr/local/nagios/var/service-perfdata service_perfdata_file_template=DATATYPE::SERVICEPERFDATAtTIMET::$TIMET$tHOSTNAME::$HOSTNAME$tSERVICEDESC::$SERVICEDESC$tSERVICEPERFDATA::$SERVICEPERFDATA$tSERVICECHECKCOMMAND::$SERVICECHECKCOMMAND$tHOSTSTATE::$HOSTSTATE$tHOSTSTATETYPE::$HOSTSTATETYPE$tSERVICESTATE::$SERVICESTATE$tSERVICESTATETYPE::$SERVICESTATETYPE$ service_perfdata_file_mode=a service_perfdata_file_processing_interval=30 service_perfdata_file_processing_command=process-service-perfdata-file
- Create the process perfdata command.
ex.
define command{
command_name process-service-perfdata-file
command_line /usr/local/nagios/libexec/process_perfdata.pl --bulk=/usr/local/nagios/var/service-perfdata
}
- For each service you wish to gather performance data for add this line or add this to the service templates.
ex.
process_perf_data 1
- Add a service extension for each service you wish to monitor to the host's configuration.
ex.
define serviceextinfo {
host_name <host's name>
service_description <service>
notes View PNP graphic
action_url /nagios/pnp/index.php?host=$HOSTNAME$&srv=$SERVICEDESC$
}
Miscellaneous
- A lot more can be configured with Nagios, and if there's anything that you're not sure with or are wondering how it works, just consult the documentation.