Nagios Support Forum

Posted: **Tue Jul 21, 2015 5:34 am**

Hi.

My setup:

hosts.cfg - contains definitions for each host under monitoring, e.g.:

define host{
        use                     linux-server
        host_name               rdss-vpn
        display_name            VPN
        address                 54.***.***.176
        }

hosts_groups.cfg - define groups:

Code: Select all

define hostgroup{
        hostgroup_name   rdss-service-server
        alias            RDSS services
        members          [...],  rdss-vpn
        }

services.cfg:

Code: Select all

define service{
        use                             local-service
        hostgroup_name                  rdss-web-server, rdss-service-server
        service_description             Memory usage
        check_command                   check_linux_memory!50!80
        notifications_enabled           1
        }

And check_linux_memory in commands.cfg:

Code: Select all

define command{
        command_name    check_linux_memory
        command_line    $USER1$/check_nrpe -H $HOSTNAME$ -c check_linux_memory -a '-f -w $ARG1$ -c $ARG2$'
        }

Problem is with few new added hosts, like rdss-vpn - Nagios won't get it's IP from hosts (please note - I have few other servers (also in groups) in check_linux_memory - all works).

Instead - I have an error in nagios.log:

[1437473407] SERVICE ALERT: rdss-vpn;Memory usage;WARNING;HARD;4;(No output on stdout) stderr: Could not resolve hostname rdss-vpn: Name or service not known

Here is example of host, where check_linux_memory works:

Code: Select all

define host{
        use                     linux-server
        host_name               www.dev.domain.com
        display_name            DEV
        address                 54.***.***.136
        }

It's group:

Code: Select all

define hostgroup{
        hostgroup_name   rdss-web-server
        alias            RDSS web servers
        members          www.dev.domain.com, www.qa.domain.com, www.staging.domain.com
        }

Can't understand - why Nagios can't resolve IP for all hosts in rdss-service-server group? All other groups are similar, also uses `check_linux_memory`, and works.

Posted: **Tue Jul 21, 2015 9:24 am**

I'm surprised anything works:

setevoy wrote:And check_linux_memory in commands.cfg:

Code: Select all

    define command{
            command_name    check_linux_memory
            command_line    $USER1$/check_nrpe -H $HOSTNAME$ -c check_linux_memory -a '-f -w $ARG1$ -c $ARG2$'
            }

$HOSTNAME$ is not what you want, (I don't think) - you want $HOSTADDRESS$. Nagios resolves $HOSTADDRESS$ on restart then passes only IPs to plugins. By using $HOSTNAME$ you're passing whatever you called the host (which could be totally arbitrary) to the plugin.

Posted: **Wed Jul 22, 2015 4:57 am**

jdalrymple wrote:
$HOSTNAME$ is not what you want, (I don't think) - you want $HOSTADDRESS$. Nagios resolves $HOSTADDRESS$ on restart then passes only IPs to plugins. By using $HOSTNAME$ you're passing whatever you called the host (which could be totally arbitrary) to the plugin.

Thanks, $HOSTADDRESS$ is what I need...

Btw - Nagios documentation isn't available anymore (this sourceforge.net website is temporarily offline.
We are working hard to restore its availability. ) - is there anywhere else same docs? It was very usefull.

Posted: **Wed Jul 22, 2015 9:45 am**

Sourceforge thing - sorry it's out of our control

Use Google's cached version of our pages - see attachment.

Re: your issue - resolved? OK to lock the topic?

Posted: **Thu Jul 23, 2015 6:12 am**

jdalrymple wrote: your issue - resolved? OK to lock the topic?

Yes, solved, thanks a lot. Topic can be closed.

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