munki_facts.py is an "admin-provided conditions" script for Munki as described here.
munki_facts.py is designed to be modular, allowing more 'facts' to be easily added without duplicating all of the code required to insert the facts into the ConditionalItems.plist.
Python modules that generate one or more facts live in the 'facts' subdirectory. They must have a 'fact()' function that returns a dictionary of keys and values.
Several sample fact modules are included.
munki_facts.py and the facts directory should be installed in /usr/local/munki/conditions.
munki_facts.py must be marked as executable.
Munki will run munki_facts.py and insert any facts it generates into the dictionary of items that are used in manifest conditional_items predicates and in installable_condition items in pkginfo files.
Any additional fact modules (that you create or obtain from others) should be copied into the /usr/local/munki/conditions/facts directory.
See https://github.com/munki/munki-facts/wiki/Community-Facts