Service Dependencies doesn't WORK????

[Miguel A. Torres]

Hello,

You are right...I have the wrong idea about service depenencies. But after to re-read the docc I think that I can use the "Service Dependencies" feature to simulate that I want. My intention is the following:

I have a service A dependent on service B. If the service B turn on the critical state the service A will not be checked. Now, with my actual configuration when this occur the service A don't turn any diferent state.

Then my question is: 

if the service A is not checked why dont't turn on other state???(for example unreachabe).

I need that a dependent servie A turn on a different (anyone) state when the master service B turn on critical state.
Is it possible with these feature??  and with other feature of nagios??


Thanks a lot.

Miguel A. Torres

-----Mensaje original-----
De: Stanley Hopcroft [mailto:Stanley.Hopcroft at IPAustralia.Gov.AU]
Enviado el: martes, 13 de mayo de 2003 5:24
Para: Miguel A. Torres
CC: nagios-users at lists.sourceforge.net
Asunto: Re: [Nagios-users] Service Dependencies doesn't WORK????


Dear Sir,

I think you have the wrong idea about service dependencies.

>From the superb docco that was installed as part of the standard Nag 
installation.

'Service dependencies are an advanced feature of Nagios that allow you
to suppress notifications and active checks of services based on the
status of one or more other services. Service dependencies are optional
and are mainly targeted at advanced users who have complicated
monitoring setups. More information on how service dependencies work
(read this!) can be found here.'

The key element is 'suprress notifications .. of services based on the 
status of .. other services'.

You cannot use dependencies to make a dependent service have the same 
state as the service it depends on; this is what 'dependencies' are 
designed to _prevent_.

Dependencies relate services in the same that 'parents' and 'children' 
relate reachability or topological dependencies (for the same reasons: 
you don't want a notification avalanche if a key node - with lots of 
dependent leaf nodes - fails).

The difference is that these are 'logical' relationships that are 
explicity configured (topol dependencies could be auto-configured by 
traceroute scans).

Service dependencies are motivated by the fact that some services rely
on databases, RADIUS, AD, Domains etc to work, and that you are not
interested in being alerted when you know that one of these has already 
failed.

An example of it's use at this site is that the logical devolution of 
plugin/check maintenance results in a server group maintaining a /bin/sh 
'system_health_check' on each of their Sol hosts. So they can keep firm 
control of access, they insist that Nag runs this check on _one_ host by 
ssh (with the hostname, as a parameter, of the box that that host will 
then check). This host then checks the others. Obviously if the ssh 
service fails on that host, none of the other hosts will be checked - 
yet probably nothing is wrong with them. In this case, all these checks 
are made dependent on the ssh service of the master, so if the ssh 
server fails, no spurious alerts are sent (to another group: DBAs) 
responsible for appplications on those boxes ...

Please read the docco. If it doesn't make sense to you you will help 
both yourself and others if you say this para or this statement doesn't 
make sense.

Yours sincerely.

 -- 
------------------------------------------------------------------------
Stanley Hopcroft
------------------------------------------------------------------------

'...No man is an island, entire of itself; every man is a piece of the
continent, a part of the main. If a clod be washed away by the sea,
Europe is the less, as well as if a promontory were, as well as if a
manor of thy friend's or of thine own were. Any man's death diminishes
me, because I am involved in mankind; and therefore never send to know
for whom the bell tolls; it tolls for thee...'

from Meditation 17, J Donne.


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