External Puppet fact listing leaf packages of Yum, without depending on yum-utils.

yum_leaf_packages.py

#!/usr/bin/env python
# This is to be used as an external Puppet fact that can tell you what are the
# leaf packages (the ones that no other package has a dependency on) installed
# on RHEL based a machine.

import logging
from yum import YumBase

logging.getLogger('yum.verbose.YumPlugins').setLevel(logging.CRITICAL)

print '%s: %s' % ('leaf_packages',
      [ package.name for package in YumBase().rpmdb.returnLeafNodes() ])