hostgroups and service dependencies?

[Assaf Flatto]

The 53 second delay is natural - as nagios is calculating the dependencies and what it 
calls "circular dependencies " - meaning it check that the definition is correct and the logic you 
defined is fine .

the delay will be there as long as you have the dependencies - as you are adding more complexity to 
the nagios operations and work logic - so it takes more time to prepare and create 
the "understanding " of the logic and requirements.

creating 100 definitions of service dependencies will not reduce the calculation time , and will 
only make you have a more "mess" in the configuration , the way you set it up is correct , and more 
elegant to read and understand by the next guy that will need to take care of the system (if that 
ever happens ).

 

On Wednesday 20 May 2009 19:35:20 Frost, Mark {PBG} wrote:
> I'm just starting to get into service dependencies.  My problem is that
> I don't quite see how I can get around doing it individually for each
> and every service and host needed.
>
> An example is if I've got 100 Windows servers all configured to be part
> of a hostgroup.  Then I've got a
>
>
> 		define service {
> 		        hostgroup_name
> prod_windows_servers
> 		        service_description             NRPE Service
> 		        check_command                   NRPE Service
> 		        use                             Production
> Windows Service
> 		}
>
> 		define service {
> 		        hostgroup_name
> prod_windows_servers
> 		        service_description             CPU Load
> 		        check_command
> check_windows_load!90%!90%
> 		        use                             Production
> Windows Service
> 		}
>
> 		define service {
> 		        hostgroup_name
> prod_windows_servers
> 		        service_description             C: Drive
> 		        check_command
> check_windows_disk!C:!90%!90%
> 		        use                             Production
> Windows Service
> 		}
>
> where the 100 servers are all part of the 'prod_windows_servers"
> hostgroup.  Here I can list the checks nice and compactly and add new
> hosts/checks merely by putting them in that hostgroup.
>
> I would like to make service checks on these boxes dependent on the
> "NRPE Service" check above.  So if the NRPE service was not responding,
> Nagios wouldn't bother sending me alerts about all the other things on
> that box it could not reach.
>
> The object definitions seem to say that I can do
>
> 		define servicedependency {
> 		        hostgroup_name
> prod_windows_servers
> 		        service_description             NRPE Service
> 		        dependent_hostgroup_name
> prod_windows_servers
> 		        dependent_service_description   C: Drive
> 		        execution_failure_criteria      n
> 		        notification_failure_criteria   w,u,c
> 		}
>
> I'm assuming that this is supposed to match up each
> 'prod_windows_servers' entry with its matching entry rather than making
> each server dependent on this servers from *every* other hostgroup
> member?
>
> Just to see, I tried this out and when I did a pre-flight check it took
> 53 seconds (checking the host and service dependencies) when it normally
> runs instantly.
>
> I'm not sure this does what I want.  Even so, I don't know that I can
> handle the 53 second wait which I imagine would escalate for each
> service I defined in this way).  The only other route I can think of is
> to create a unique servicedepency definition for each of these.  That's
> 100 x n dependency definitions, where n is the number of other services
> I'm checking on each of these boxes.
>
> Am I looking at this the wrong way?  Is there an easier way to do this?
>
> Thanks
>
> Mark
>
>
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-- 
Assaf Flatto
SSP Ops Team
Linux System Administrator
169 Euston Road, London, NW1 2AE

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