passive checks and check_command

[Stanley Hopcroft]

Dear Sir,

I am writing to thank you for your letter and say,

On Fri, Oct 10, 2003 at 02:27:31PM +0100, tvilliers wrote:
> 
> Nagios requires that "check_command" exists in any defined service. With
> passive services, a "check_command" is an anomaly, as the checking is really
> done by the main engine at the specified command_check_interval in the 
> main config file. 
>

That is my understanding too.

 
> Setting the check_command to "" (ie, a blank raw command line) is one way
> to circumvent the requirement, but this is not mentioned explicitly in the
> docs. Is this correct, and more importantly, why have such a requirement 
> in the first place with passive services?
> 

It's hard to answer without being the developer, but requiring a command
definition for a passive service be the same as for an actively checked
service eliminates any extra parsing requirements of the command file.

However, there is a benefit in having a legitimate command defined for a
passive service in that service states that cannot otherwise be reset,
can be reset by scheduling the passive service check with a command like
'ping'.

Some trap services (eg newRoot [of spanning tree]) fall into this
category.

Without this handly little feature one could either

. submit a service check result - entering some soothing message
manually.

. hack the mib to accept a bogon trap that will cause your trap handler
to send an Ok and then use snmptrap or similar to send that bogon trap.

Scheduling a service check is simpler and faster.


> Tielman de Villiers

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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