Facts and built-in variables

Before requesting a catalog for a managed node, or compiling one with puppet apply, Puppet collects system information, called facts, by using the Facter tool. The facts are assigned as values to variables that you can use anywhere in your manifests. Puppet also sets some additional special variables, called built-in variables, which behave a lot like facts.

Puppet code can access the following facts when compiling a catalog:

Core facts from Facter .
Custom facts and external facts that are present in your modules.

To see the fact values for a node, run facter -p on the command line, or browse facts on node detail pages in the Puppet Enterprise console. You can also use the PuppetDBAPI to explore or build tools to search and report on your infrastructure's facts.

Puppet honors fact values of of any data type. It does not convert Boolean, numeric, or structured facts to strings.

Accessing facts from Puppet code

When you write Puppet code, you can access facts with the $facts['fact_name'] hash.
Built-in variables

In addition to Facter's core facts and custom facts, Puppet creates several variables for a node to facilitate managing it. These variables are called trusted facts, server facts, agent facts, server variables, and compiler variables.