Monitoring cross-server services?

[Carroll, Jim P [Contractor]]

I've got quite a number of service dependencies defined, and they add
absolutely nothing to the service detail page.  Basically I set up a
rudimentary check for NRPE ('echo "NRPE is OK"' in nrpe.cfg), and made all
the other NRPE checks for that host dependent on the rudimentary check.  If
NRPE is down, I want *one* page, not however many NRPE checks I'm doing.
Ordinarily I wouldn't expect NRPE to be down (since it's kicked off from
(x)inetd), but if an admin rebuilds a host or makes some other unfortunate
change to (x)inetd, we don't want to be flooded with notifications; a simple
"um... excuse me?  NRPE doesn't seem to be up" is just fine.

My case differs from your case in that my dependencies occur on the same
host, and yours occur on different hosts.  Having said that, if I
acknowledge that NRPE is down (the depended-on service), that doesn't
automatically flag any other services, or the host itself for that matter,
as being down/acknowledged/ignored.

If you're still uncertain, your best bet is to create a trivial case on 2 or
3 of your lesser hosts.  Use netcat to listen on some arbitrary ports, and
have Nagios poke at those 'services'.  Then kill netcat on the 'depended-on'
host.  Wait for Nagios to notify you.  Acknowledge it.  Kill netcat on one
of the 'dependent' hosts.  Wait for Nagios to notify you.  And wait and
wait, because you shouldn't hear a peep.  Bring netcat back up on the first
host.  Eventually you should get a notification that the 'service' on the
second host is down.

In this scenario, any other services should be completely independent;
Nagios should still notify you if one of those goes down.  (Feel free to
test this in whatever permutations/combinations with this scenario, as
well.)

HTH.

jc

> -----Original Message-----
> From: Steven Grimm [mailto:koreth-nagios at midwinter.com]
> Sent: Tuesday, January 21, 2003 10:39 AM
> To: nagios-users at sourceforge.net
> Subject: Re: [Nagios-users] Monitoring cross-server services?
> 
> 
> A service dependency, really; I want to catch any situations 
> where my app
> isn't connected to its peers even if all the hosts involved 
> are alive and
> otherwise working fine.
> 
> Service dependencies seem like they'd work if I treated the connection
> between each unique pair of hosts as a separate service; in 
> that case I
> could make each of those pseudo-services dependent on the services I
> define for my app as a whole on its two hosts.  But I think 
> that'd clutter
> up my service detail page pretty quickly.
> 
> -Steve
> 
> 
> On Tue, Jan 21, 2003 at 09:21:54AM -0600, Carroll, Jim P 
> [Contractor] wrote:
> > Depends.
> > 
> > Is it a service dependency you're looking to define, or a 
> host dependency?
> > 
> > jc
> 
> 
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