Patches for improved NEB control

[Ethan Galstad]

bobi at netshel.net wrote:
> Attached is a patch-set I would like some feedback on.
> 
> The purpose of this patch is to allow Nagios the ability to delegate the
> execution of service checks to a NEB module.
> 
> Why would we want to do this?  I'm glad you asked...
> 
> The point is to allow Nagios to scale efficiently in large-scale
> environments by delegating service checks to multi-node "check" clusters. 
> That is, it facilitates the creation of a Nagios Service Check Cluster (or
> multiple independent clusters,) that can be deployed in either one
> location or multiple locations.
[snip]

Thanks for the patch Bob.  I've been thinking about this and its effect 
on service checks and other modules and have made a few tweaks to your 
original patch.  The patch will be applied to Nagios 3.x.

1. I have applied this to host checks as well as service checks

2. A new NEBERROR_CALLBACKCANCEL error has been added, which is similar 
to the CALLBACKOVERRIDE you suggested.  There are some slight 
differences in how Nagios deals with the different return codes - see 
the CVS patch for more.

3. Instead of allowing modules to override checks during the 
SERVICECHECK_INITIATE callback, I added a new one called 
SERVICECHECK_ASYNC_PRECHECK.  This callback occurs earlier in the 
service check logic, which is cleaner with the new Nagios 3.x code.

4. Nagios 3.x supports both synchronous host checks (Nagios 2.x style) 
and async checks as well (performed in parallel like service checks). 
Two new callbacks have been added to allow modules to override internal 
host checks: HOSTCHECK_SYNC_PRECHECK and HOSTCHECK_ASYNC_PRECHECK.


Ethan Galstad,
Nagios Developer
---
Email: nagios at nagios.org
Website: http://www.nagios.org

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