Distributed Nagios and scheduling service check from the central server

[Dustin Kamper]

> -----Original Message-----
> From: nagios-users-admin at lists.sourceforge.net [mailto:nagios-users-
> admin at lists.sourceforge.net] On Behalf Of Marc Powell
> Sent: Thursday, July 14, 2005 4:14 PM
> To: nagios-users at lists.sourceforge.net
> Subject: RE: [Nagios-users] Distributed Nagios and scheduling service
> check from the central server

Right....   ;)

> Please try to avoid top-posting.
> 
> sucks.
> posting
> top
> why
> is
> This
> 
> > -----Original Message-----
> > From: nagios-users-admin at lists.sourceforge.net [mailto:nagios-users-
> > admin at lists.sourceforge.net] On Behalf Of Dustin Kamper
> > Sent: Thursday, July 14, 2005 3:40 PM
> > To: nagios-users at lists.sourceforge.net
> > Subject: RE: [Nagios-users] Distributed Nagios and scheduling
service
> > check from the central server
> >
> 
> > All of the checks on the distributed servers can be executed by the
> > central server with no issues.  So I just used a 'concatonated'
> version
> 
> > From what I can figure out, freshness checks base the 'freshness' of
> the
> > the results on the normal_check_interval setting.  Since
> > normal_check_interval controls the timming of the active checks, you
> > must turn active checks off so you don't have the central server
> > checking what the distributed servers are already checking.  When
> active
> > service checks are turned off, the 'Re-schedule the next check of
this
> > service' link is not available from the web page.
> 
> The documentation is unambiguous, no need to figure anything out --
> 
> http://nagios.sourceforge.net/docs/1_0/xodtemplate.html#service
> 
> freshness_threshold: 	This directive is used to specify the freshness
> threshold (in seconds) for this service. If you set this directive to
a
> value of 0, Nagios will determine a freshness threshold to use
> automatically.
> 
> And
> 
> http://nagios.sourceforge.net/docs/1_0/freshness.html
> 
> "Assuming you're using the template-based object configuration
file(s),
> you need to configure service definitions as follows.
> 
>     * The check_freshness option in the service definition should be
set
> to 1. This enables "freshness" checking for the service.
>     * The freshness_threshold option in the service definition should
be
> set to a value (in seconds) which reflects how "fresh" the results for
> the service should be.
>     * The check_command option in the service definition should
reflect
> valid command that should be used to actively check the service when
it
> is detected as being "stale".
> 
> How The Freshness Threshold Works
> 
> Nagios periodically checks the "freshness" of the results for all
> services that have freshness checking enabled. The freshness_threshold
> option in each service definition is used to determine how "fresh" the
> results for each service should be. For example, if you set the
> freshness_threshold option to 60 for one of your services, Nagios will
> consider that service to be "stale" if its results are older than 60
> seconds (1 minute). If you do not specify a value for the
> freshness_threshold option (or you set it to zero), Nagios will
> automatically calculate a "freshness" threshold to use by looking at
> either the normal_check_interval or retry_check_interval options
> (depending on what type of state the service is currently in)."
> 
> 
> >
> > I would like 1 source of Nagios for monitoring all of my servers but
> > would like to spread the load of all the service checks to many
> > distributed servers.  It would be a pain to have to go to one of the
> > distributed servers just to run one re-scheduled service check on
> > demand.
> >
> > Now I'm not sure that a distributed solution is going to work for my
> > monitoring needs.  Any pointers would be appreciated.
> 
> Active_checks_enabled 1
> Passive_checks_enabled 1
> check_period none
> check_freshness 1
> freshness_threshold 300 ; bad if 5 minutes old
> check_command some_valid_check_command

Ok, I tested this and found that the check_period effects the freshness
checking.  If I set it to none (which is defined) then freshness is
never checked.  If set to 24x7 then it is always checked.  I verified
that active checks where not being performed by setting
active_checks_enabled to 0 for each check_period test (4 test in all).
I wish there was a freshness_check_period setting.

Oh...BTW, I am using Nagios 2.0b3.  I am assuming that there is not much
difference in the logic of this since 1.0.  I guess I should test it
tho.

Any other pointers?


> Since you can execute all of your checks from the central server with
no
> problems, this should be a workable solution for you (it's been for us
> for 4 years with 4 collectors and 2900+ passive service checks but to
> each his own). If you _really, really_ wanted to execute the checks
from
> the remote host, write a script to ssh to the appropriate nagios
machine
> and drop a SCHEDULE_SVC_CHECK external command into the pipe.
> check_by_ssh might be a good wrapper/start. Make that script the
> check_command for the services on your central machine. That way,
> freshness checks will be executed from the remote machine as well as
> forced checks.
>
> --
> Marc
> 
> 
>


-Dustin




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