puppet_env.rb

#
# Set up our puppet environment
# 

unless attrib?("puppet_env")
  hostname = attrib?("hostname")
  fqdn = attrib?("fqdn")
  if fqdn =~ /amazonaws.com$/
    replace_attrib("puppet_env", "prod")
  else
    if hostname =~ /^.+?\d+(.+)$/
      replace_attrib("puppet_env", $1)
    else
      replace_attrib("puppet_env", "prod")
    end
  end
end

updates.rb

    # Add an attribute to this node. Requires a name and either a string or
    # array of values.
    #
    # Will be cumulative!
    def add_attrib(name, values)
      load unless @node
      @node.attribs << { :name => name, :values => values.kind_of?(Array) ? values : [ values ] }
    end
    
    # Replace the attribute with the given name's values in place.
    # Will add a new attribute if it needs to.
    def replace_attrib(name, values)
      exists = @node.attribs.detect { |a| a[:name] == name }
      if exists
        exists[:values] = values.kind_of?(Array) ? values : [ values ]
      else
        add_attrib(name, values)
      end
    end