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

[L B]

Hi all,

 I didn't have any feedback from my patch, do you consider this
feature useless ?

As a reminder, I would like Nagios not to raise an error when it
founds an empty hostgroup during the configuration check :

 - I define all my service checks applied to hostgroups, for example
check_ftp applied to ftp-server-hostgroup
 - I define hosts
 - I add the hosts into the relevant hostgroups if I want the service
check to be applied :
   hostgroups +ftp-server-hostgroup,http-server-hostgroup
 - Adding a service check is really easy like this and I can see all
my FTP/HTTP/Whatever servers in the web interface in their hostgroup.

 But to do this, I may have empty hostgroups, and that's normal : I
don't want to have to enable the hostgroup (by removing register 0  in
the service definition or ...)  if I decide to add a host into it.


(why should it be an error to have an empty hostgroup ?)

Thanks!
--
LB

On Tue, Nov 11, 2008 at 12:43 PM, L B <bertignac at gmail.com> wrote:
> 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.
>



-- 
L.B.

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