The error people are likely to see is:

/Library/Ruby/Site/1.8/plist/parser.rb:67: warning: already initialized constant TEXT
/Library/Ruby/Site/1.8/plist/parser.rb:68: warning: already initialized constant XMLDECL_PATTERN
/Library/Ruby/Site/1.8/plist/parser.rb:69: warning: already initialized constant DOCTYPE_PATTERN
/Library/Ruby/Site/1.8/plist/parser.rb:70: warning: already initialized constant COMMENT_START
/Library/Ruby/Site/1.8/plist/parser.rb:71: warning: already initialized constant COMMENT_END
/Library/Ruby/Site/1.8/plist.rb:21: warning: already initialized constant VERSION
NoMethodError: undefined method ‘new’ for nil:NilClass

when running facter >= 1.5.0 with puppet.

Sample code to illustrate the problem:

#!/usr/bin/env ruby

require 'puppet/util/plist'
require 'facter/util/plist'

xml_data = %x{system_profiler -xml SPHardwareDataType}
puts Plist::parse_xml( xml_data )

will produce the above error.

I’m not sure what the long term solution here is, but I offer several alternatives:

Neither Puppet or Facter include plist, but require it to be installed separately.¶

Puppet does not include plist, but Facter does (given that Facter is a requirement for Puppet)¶

We do something hacky like this in Facter for the require statements¶

begin
  Plist
rescue NameError
  require 'facter/util/plist'
end

eeeeeeew.

As it stands, Facter 1.5.0 and higher are broken when used with Puppet on Mac OS X until this is resolved.

Of the three options above, I think the second is the most palatable long term, but requires changes to Puppet. The first option is probably the most ‘correct’ option, given some users may in fact install plist themselves and try to use in Facter facts or Puppet plugins, but adds an annoying barrier to entry for getting Puppet/Facter installed on Mac OS X.

I don’t mind packaging plist up with Facter and Puppet on Mac OS X in a single metapackage if that’s the best solution everyone agrees on.