fqdn_rand_base64.rb

Puppet::Parser::Functions::newfunction(
  :fqdn_rand_base64,
  :arity => -2,
  :type => :rvalue,
  :doc => "Usage: `fqdn_rand_base64(LENGTH, [SEED])`. LENGTH is required and
  must be a positive integer; SEED is optional and may be any number or string.

  Generates a random base64 string LENGTH characters long, combining the `$fqdn`
  fact and the value of SEED for repeatable randomness.  (That is, each node
  will get a different random string from this function, but a given node's
  result will be the same every time unless its hostname changes.)") do |args|
    raise ArgumentError, "First argument must be positive integer" unless args[0].to_i > 0

    length = args.shift.to_i
    ints = (length.to_f / 4.0).ceil
    numeric_salt = []
    # generate enough unique 4-byte integers with fqdn_rand to build our string
    for current in 1..ints
      numeric_salt << function_fqdn_rand([2**32, (args + [current]).join(':')]).to_i
    end

    # pack into base64
    [numeric_salt.pack('L*')].pack('m0')[0, length]
end