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Puppet agent settings issue

Experienced a strange puppet agent 4.8 configuration issue this week. To properly distribute the agent runs over time to even out puppet master load I wanted to configure the splay settings properly. There are two settings:
  • A boolean "splay" to enable/disable splaying
  • A range limiter "splayLimit" to control the randomization
What first confused me was the "splay" was not on per-default. Of course when using the open source version it makes sense to have it off. Having it on per-default sounds more like an enterprise feature :-) No matter the default after deploying an agent config with settings like this
[agent]
runInterval = 3600
splay = true
splayLimit = 3600
... nothing happened. Runs were still not randomized. Checking the active configuration with
# puppet config print | grep splay
splay=false
splayLimit=1800
turned out that my config settings were not working at all. What was utterly confusing is that even the runInterval was reported as 1800 (which is the default value). But while the splay just did not work the effective runInterval was 3600! After hours of debugging it, I happened to read the puppet documentation section that covers the config sections like [agent] and [main]. It says that [main] configures global settings and other sections can override the settings in [main], which makes sense. But it just doesn't work this way. In the end the solution was using [main] as config section instead of [agent]:
[main]
runInterval=3600
splay=true
splayLimit=3600
and with this config "puppet config print" finally reported the settings as effective and the runtime behaviour had the expected randomization. Maybe I misread something somewhere, but this is really hard to debug. And INI file are not really helpful in Unix. Overriding works better default files and with drop dirs.