I'm trying to write a puppet function that calls my hosting environment (rackspace cloud atm) to list servers, then update my hosts file.

My get_hosts function is currently this:

require 'rubygems'
require 'cloudservers'

module Puppet::Parser::Functions
  newfunction(:get_hosts, :type => :rvalue) do |args|
    unless args.length == 1
      raise Puppet::ParseError, "Must provide the datacenter"
    end

    DC       = args[0] 
    USERNAME = DC == "us" ? "..." : "..."
    API_KEY  = DC == "us" ? "..." : "..."
    AUTH_URL = DC == "us" ? CloudServers::AUTH_USA : CloudServers::AUTH_UK
    DOMAIN   = "..."

    cs = CloudServers::Connection.new(:username => USERNAME, :api_key => API_KEY, :auth_url => AUTH_URL)

    cs.list_servers_detail.map {|server|
      server.map {|s| { s[:name] + "." + DC + DOMAIN => {
                          :ip      => s[:addresses][:private][0],
                          :aliases => s[:name]
      }}}
    }
  end
end

And I have a hosts.pp that calls this and 'should' write it to /etc/hosts.

class hosts::us {
    $hosts = get_hosts("us")

    hostentry { $hosts: }
}

define hostentry() {
  host{ $name: ip => $name[ip], host_aliases => $name[aliases] }
}

As you can imagine, this isn't currently working and I'm getting a 'Symbol as array index at /etc/puppet/manifests/hosts.pp:2' error. I imagine, once I've realised what I'm currently doing wrong there will be more errors to come.

Is this a good idea? Can someone help me work out how to do this?