This message was deleted.

I maybe answered my own question. It looks like there are restrictions for trusted facts. "Restriction: Regular expressions, resource references, and other keywords (such as

undef

) are not supported."

Null is a difficult concept in general. Normally we want to check for things that do exist rather than things that don’t exist. The difference lies in how PuppetDB evaluates that state, and how the classifier evaluates that state. In the UI, we do our best to map classifier rules to puppetdb rules that will resolve in the same classification application (which nodes will be classified). There are some edge cases around null and “don’t exist” cases that you might be running into.