Verion 2.0b4 how does cgi's nagios_check_command work?

[John P. Rouillard]

In message <434D5AF2.7010504 at op5.se>,
Andreas Ericsson writes:

>John P. Rouillard wrote:
>> In message <43467920.4070508 at op5.se>,
>> Andreas Ericsson writes:
>>>John P. Rouillard wrote:
>>>
>>>>In message <43465AB9.6020304 at op5.se>,
>>>>Andreas Ericsson writes:
>>>>
>>>>>John P. Rouillard wrote:
>> 
>> 
>>>>>>The reason I ask is
>>>>>>that nagios was down and the cgi's all happily reported that it was
>>>>>>up. Could this be because the host and service status files were
>>>>>>available since the machine crashed?
>>>>>
>>>>>Yes, that's almost certainly it. There is no really good way of 
>>>>>detecting that nagios is actually running unless you're logged in as 
>>>>>root.
>>>>
>>>>Hmm, I am not sure I follow why you need to be logged in as root.
>>>
>>>Because otherwise you shouldn't have access to reading process 
>>>information about another users process.
>>>
>>>>Why not stat the status.log file and check to see if its (mtime)
>>>>timestamp is less than the setting of:
>>>>
>>>>	status_update_interval*2
>>>>
>>>>if aggregate_status_updates is enabled? One could also allow a setting
>>>>"freshness_threshold" in cgi.cfg that is the number of seconds/minutes
>>>>old the status.dat file is allowed to be if aggregate_status_updates
>>>>isn't set.
>>>
>>>Good idea. Write the code for it and submit a patch.
>> 
>> Actually not so much a good idea. There is actully a creation
>> datestamp in the status.dat file I was going to use, but I decided to
>> run an experiment first. I have my status_update_interval set to 3
>> seconds.
>> 
>> I used check_fileage to warn me if the file's age was over 3 seconds
>> and ran it in a while loop. It failed often. The longest interval was
>> 139 seconds between updates with a number of periods of 20-30 seconds.
>> 
>> My guesses are: nagios only writes the status file when it needs to.
>
>This is correct. The status_update_interval is never checked, although 
>the status is updated every time a service changes either state or 
>output (or a host, for that matter).

Ideally nagios would provide a next_check_time in the status.dat, but
I wonder if that could be usefully intuited from:

  min(
      min(next_check time on services) + service_check_timeout),
      min(next_check time on hosts) + host_check_timeout)
     )

Possible problems: on demand host checks (if part of a network is
down) could screw up the timing since everything else stops.

Just because a service check is scheduled doesn't mean that it is
going to run (time period may be wrong etc), but if its determined to
be non-runnable the escheduled time for it should cause a re-write of
the status.dat file correct?

There has to be an easier way of determining if nagios is running
doesn't there?

				-- rouilj
John Rouillard
===========================================================================
My employers don't acknowledge my existence much less my opinions.


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