Writing Facts

Facts are written as Python classes. They provide a command (as a string or method) and a process function. The command is executed on the target host and the output passed (as a list of lines) to the process handler to generate fact data.

Facts can output any data structure, normally a list or dict. They often make heavy use of regex to parse the output.

Example: getting the list of files in a directory

This fact returns a list of files found in a given directory.

from pyinfra.api import FactBase

class FindFiles(FactBase):
    '''
    Returns a list of files from a start point, recursively using find.
    '''

    def command(self, name):
        # Find files in the given location
        return 'find {0} -type f'.format(name)

    def process(self, output):
        # Return the list of lines (files) as-is
        return output