Writing custom facts

A typical fact in Facter is an collection of several elements, and is written either as a simple value (“flat” fact) or as structured data (“structured” fact). This page shows you how to write and format facts correctly.

You must be able to distinguish facts from resolutions. A fact is a piece of information about a given node, while a resolution is a way of determining the value of an applicable fact. The following is a structure of a fact:

 
Facter.add(:my_custom_fact) do
   <resolution>
end

A single fact can have multiple resolutions. A resolution details how, when and in which order to obtain the value for a fact. It is common to have different resolutions for different operating systems. To add a new resolution to a fact, you add the fact again but with a different setcode statement.

You need some familiarity with Ruby to understand most of these examples. For an introduction, see out the Custom facts overview. For information on how to add custom facts to modules, see Module plug-in types.