[Nagiosplug-devel] Working on testcases
Ton Voon
ton.voon at altinity.com
Fri Nov 4 01:07:27 CET 2005
On 4 Nov 2005, at 07:39, sean finney wrote:
> hi ton,
>
> On Thu, Nov 03, 2005 at 03:14:18PM +0000, Ton Voon wrote:
>> - if a server does not exist, it looks like check_tcp uses usage2 to
>> alert the error. This returns a status of UNKNOWN. The tests
>> currently check for CRITICAL. Which should it be? The plugin
>> documentation says UNKNOWN is: "Invalid command line arguments were
>> supplied to the plugin or the plugin was unable to check the status
>> of the given hosts/service", which does suggest hostname invalid, but
>> then I'm worried that Nagios needs to be specifically configured to
>> alert on unknown states.
>>
>> Any thoughts?
>
> my thought is that for most plugins (except the dns-related ones),
> UNKNOWN seems a proper state. chances are there's something
> monitoring DNS that will issue a CRITICAL anyway. however, i don't
> feel to comitted to this opinion and would be interested to hear
> the counter-argument.
My "bad" scenario:
- Nagios configured to alert on critical/warning - but not unknown
- for a check_http on wiki.internal.company.com
- Nagios also configured for critical on check_dns to check
nameserver, but not specific wiki.internal.company.com record
- Someone deletes the DNS entry for wiki.internal.company.com by
mistake
- Nagios says check_dns is okay (nameserver still running)
- check_http on wiki.internal.company.com returns UNKNOWN because
cannot resolve hostname
- however, no alert. Sys admin gets b0ll0cked for not spotting
problem :(
Three ways to fix at the configuration level:
- check_http against IP address, but then removes point of DNS
- alert on unknown, but then what's the point of unknown?
- for each hostname used, configure a check_dns for it. But that
sounds like a huge (and unobvious) overhead
Cons to using CRITICAL:
- if DNS goes, all services that rely on hostname lookup via DNS
will go CRITICAL and flood alerts (but that, I think, is an obvious
reaction)
Am I worrying too much?
Ton
http://www.altinity.com
T: +44 (0)870 787 9243
F: +44 (0)845 280 1725
Skype: tonvoon
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