puppet fact to determine dns sub-domain to use for dns resolution.

environment.rb

#Environment.rb
##Determines dns from hostname

Facter.add("mydns") do
   setcode do
     Senv = Facter.value('hostname').scan(/(^\D+\d)/)
     if Senv.any?
       Senv.to_s + ".promnetwork.com"
     else
       "no environment"  
     end
   end
end