Visualizing Puppet Circular Dependencies

# Make sense of puppet circular dependency error messages.
# Tags: graphviz, puppet
# See output at http://i41.tinypic.com/b6yeqv.jpg

$ cat circular.pp
node default {
  exec { "/a": require => Exec["/b"] }
  exec { "/b": require => Exec["/c"] }
  exec { "/c": require => Exec["/a"] }
}
$ puppet --color=false circular.pp \
   | grep "the following relationships: " \
   | awk -F"the following relationships: " '{ print $2 }' \
   | tr , \\n \
   |  (echo "digraph {"; perl -pi -e's/^\s*(\S.*\S) => (\S.*\S)\s*$/ "$1" -> "$2";\n/'; echo "}") \
   | dot -Tpdf > circular.pdf