Using Nagios to monitor "service-less" hosts

[Giles Coochey]

Hi Andy,

I'm just not so sure, from the v2 docs.. (http://nagios.sourceforge.net/docs/2_0/checkscheduling.html):

-------------
Host Checks 

Unlike service checks, host checks are not scheduled on a regular basis. Instead they are run on demand, as Nagios sees a need. This is a common question asked by users, so it needs to be clarified. 

One instance where Nagios checks the status of a host is when a service check results in a non-OK status. Nagios checks the host to decide whether or not the host is up, down, or unreachable. If the first host check returns a non-OK state, Nagios will keep pounding out checks of the host until either (a) the maximum number of host checks (specified by the max_attempts option in the host definition) is reached or (b) a host check results in an OK state. 

Also of note - when Nagios is check the status of a host, it holds off on doing anything else (executing new service checks, processing other service check results, etc). This can slow things down a bit and cause pending service checks to be delayed for a while, but it is necessary to determine the status of the host before Nagios can take any further action on the service(s) that are having problems. 
-------------

Now I'm really getting confused. Perhaps the documentation is out of date, I've not seen active_checks_enabled defined for hosts, I'm not ever tried it either, so I suppose it might just be somewhat undocumented, not saying it doesn't work, but becoming sure that it wasn't in the original Nagios design.

> -----Original Message-----
> From: nagios-users-bounces at lists.sourceforge.net 
> [mailto:nagios-users-bounces at lists.sourceforge.net] On Behalf 
> Of Andy Shellam (Mailing Lists)
> Sent: 07 November 2006 16:54
> To: Nagios Users mailinglist
> Subject: Re: [Nagios-users] Using Nagios to monitor 
> "service-less" hosts
> 
> Giles Coochey wrote:
> >
> > I thought host checks were only there to prevent you from 
> receiving multiple service notifications when a host went down.
> >   
> Even if that's the way it was designed, you can still use it to 
> determine if a host is up or down :)  Also, if you HAD to 
> have a service 
> for each host, Nagios wouldn't even start up.
> >
> > Are you sure? Is it not just alerting you it's down when 
> nagios goes to work out where the network outage is (assuming 
> you have parenting set).
> >
> >   
> The gateways are the 2 main parents - there's nothing above them, but 
> they do have servers below them.  The people that manage the 
> SC_Gateway 
> are re-routing to a new floor in the data-center, so at least 
> once a day 
> the router goes down for a few seconds when they apply new 
> routing rules 
> - Nagios tells me whenever this happens.
> > Which I thought was because it didn't have a service 
> attached to it, Nagios won't check a host if it doesn't have 
> a service (at least that's how I've evaluated it's behaviour).
> >   
> No, hosts AND services have an active_checks_enabled 
> parameter - so you 
> can disable active checks on a host, but still check the 
> services, and 
> vice versa.
> >
> > Actually I thought Fermín's thoughts were more closer to 
> the the way that my Nagios functions and it seems to be the 
> way I expect it to function.
> >
> > If I want a serviceless host then I just attach it to the 
> ping service (or similar). Though generally, any service-less 
> hosts we would have we'd probably turn off and not put in 
> nagios at all :-)
> >   
> That's basically what the check-active-host is - it's a ping command 
> that saves you having to have a Ping service (because I 
> wouldn't exactly 
> class ping-ability as a service.)
> > 
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-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________
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::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. 
::: Messages without supporting info will risk being sent to /dev/null