puppetlabs/facter — pull request #244 by hkenney (2012-06-15 22:20:12+00:00)
Title: (#2157) External Fact Support

Add functionally to Facter to allow support of external facts in other formats, including `yaml`, `txt`, and `json`.

A few notable details:
1) It does not require a `json` gem unless you are writing `json` facts.
2) There is a command line option to specify a directory from which to read external facts (but there are defaults if a directory is not specified).
3) There is a command line option to 'turn off' external facts.
4) If an external fact has the same name as one of the standard Facter facts, it will default to using the value obtained from the external fact.

More details on how to use external facts here:
http://docs.puppetlabs.com/guides/custom_facts.html