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05

Kühe am Morgen

Posted Wed May 3 07:15:07 2017 Florian Lohoff in

Beim Aufwachen in Kuhaugen schauen.

Mr Fox

Posted Wed May 17 19:09:17 2017 Florian Lohoff in

Wenn die Kollegen einem auf Amazon einen Foxplug bestellen.

Spass im Büro

icinga2 check scheduler

Posted Fri May 19 12:09:37 2017 Florian Lohoff in

For me icinga2 has been a pain in the ass as of its release. My primary problem with icinga1 was the inflexibility of defining dependeny. A host could not depend on a service which imho is broken. The host connected to a switch depends on the switch, and on the vlan/bridge on the switch. So i would like to construct/define a dependency on the vlan check. Icinga1 could not do this, as does icinga2.

Now - one needs to do the transition on day or the other so i did. The next issue came up. Icinga2 does not include the embedded perl interepreter anymore. This means you'll be fighting against a 10 fold increase in check runtime. The reasoning here is that this could not be made stable. I wonder why Apache is able to this but not the Icinga2 devs. So i rewrote my most performance sensitive checks from Perl to c++.

Lately i am having trouble because on my larger network devices i am seeing flapping interfaces. That means - from time to time (multiple times a day) a bulk of interfaces goes into the "Unknown" state which means my check could not get an SNMP response from the Device.

This came up when i migrated the Icinga2 instance from a virtual machine to bare metal. I could not explain the symptom and started debugging on a firewall which had been installed inbetween the host and the network.

No luck so far.

Today then i had another look because my collectd/influx/grafana host monitoring showed network traffic more like a heart beat. Every hour exporting the configuration was a beat which swung out into an "null line" e.g. an average.

After investigating a bit more i found that reloading the icinga2 config would erradicate the check scheduling queue which caused icinga2 to do a recalculation which made the check scheduling very much spikey in the check_interval interval.

It seems the Icinga2 (in my case 2.6.3) check scheduler does a very bad job in averaging out the check executions over their check_interval.

This is a graph i created using some shell and gnuplot vodoo. The event at 9:36:44 is the config generation issueing an service icinga2 reload which causes icinga2 to not issue/schedule checks for nearly a minute.

Warnhinweis

Posted Wed May 24 07:01:07 2017 Florian Lohoff in

Eben erst entdeckt. Ein Hinweis auf dem Karton des Fernreisefahrradanhängers.

given { when {} }

Posted Tue May 30 09:52:18 2017 Florian Lohoff in

Wenn man in Perl eine switch/case ähnliches Konstrukt nutzen möchte ist das schon ein wenig haarig. Vor allem dann wenn man zwischen Debian/Squeeze bis Debian/Stretch alles supporten möchte.

Es bleiben einem nur Versionabhängige use statements.

use if $] > 5.10, "experimental" => qw/smartmatch/;
use if $] <= 5.10, "feature" => qw/switch/;

Und schon darf das script given { when {} } benutzen.