Empty hostgroup check in the configuration arbitrary or limitation in nagios core ?

[L B]

Dear Andreas,

 Thanks for your answer. I had a look to the code (for the first
time), and I did a patch, which was too easy in my opinion. Please
find attach the modification I did, the xodtemplate_duplicate_services
looked like the only function to modify to me.

 I built Nagios and it runs without problem so far, with the expected behavior.

 Sorry if the patch is stupid, I'm not yet familiar with Nagios
code... I guess the only side effect is that it might break some
service duplication checks that were done before.

 Your opinion will be very much appreciated !

Thanks,

LB

On Tue, Nov 11, 2008 at 11:03 AM, Andreas Ericsson <ae at op5.se> wrote:
> L B wrote:
>> Hello,
>>
>> I have many nagios servers for different regions in the world, and I
>> want to create a standard installation with a set of hostgroups,
>> commands, and services with default thresholds, for all my Nagios
>> admins. My services are applied to hostgroups, and I want to add a
>> check to a host only by adding this host to the relevant hostgroup.
>>
>> Example :
>>  - I define a command check_dns
>>  - I define a hostgroup dns-server-hostgroup
>>  - I define a service check_dns applied to dns-server-hostgroup
>>
>> Then I define a host, and if it's a DNS server, I add it to the DNS
>> hostgroup (I'm running Nagios 3):
>> define host {
>> ....
>> hostgroups  +dns-server-hostgroup
>> }
>>
>> This works very well in my configuration except that if I install a
>> nagios server in a new region, and they not have for example a NFS
>> server, I will get an error because nfs-server-hostgroup is empty. I
>> fixed this by adding "register 0" to the service definition, but that
>> means the admins have to comment out this line to enable the check on
>> the hostgroup.
>>
>> So I would like to be allowed to create checks on empty hostgroups,
>> and of course if the hostgroup is empty, no check is done.
>>
>> Is there something technically in the nagios core that prevents
>> creating empty hostgroups
>
> No, but when a service is assigned to a hostgroup, that hostgroup
> is already expanded (and found to contain zero hosts), so the service
> is assigned to no host at all, but still doesn't have "register 0"
> in it, so it's a faulty service.
>
>> or is it an arbitrary configuration check
>> because it's assumed that a user probably doesn't want to check a
>> service on a empty hostgroup ?
>>
>> I find this configuration approach very convenient so I hope it's the
>> second answer ! :-)
>>
>
> It's a bit of both actually. You'd need to submit a patch to get Nagios
> to accept services linking to empty hostgroups though.
>
> --
> Andreas Ericsson                   andreas.ericsson at op5.se
> OP5 AB                             www.op5.se
> Tel: +46 8-230225                  Fax: +46 8-230231
>
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-- 
L.B.
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