strawman - a simple puppet template checker

strawman.rb

#!/usr/bin/env ruby
# strawman - a simple puppet template checker.
# use like:
# echo 'fqdn => test.example.org\n$webserver = ["host1", "host2"]' | strawman template.erb
# where fqdn is in facter format:
# key => value
# and $webserver is a global ruby var, like in your manifests
# seperated by newlines, delivered on STDIN
require 'erb'

if ARGV[0].nil? then
    puts 'Usage: echo "fqdn => test.example.org\n$var = \'test\'" | ' + __FILE__ + ' <template.erb>'
    exit
end

debug = false

facts = {}
facts['strawman'] = 'ip-1-2-3-4'

input = (STDIN.tty?) ? nil : STDIN.read.split("\n")
input.each do |line|
    if line =~ /^\$/ then
        line = $'
        eval line, TOPLEVEL_BINDING
    else
        k, v = line.split(' => ')
        facts[k] = v
    end
end

template = File.read(ARGV[0])

STDERR.puts "Using these facts:" if debug

facts.each do |k,v|
    STDERR.puts k + " : " +  v if debug

    global_ns_key = "\\$" + k
    root_ns_key   = "\\$::" + k
    template = template.gsub /#{global_ns_key}/,  "facts['" + k + "']"
    template = template.gsub /#{root_ns_key}/,  "facts['" + k + "']"
end

STDERR.puts template if debug

renderer = ERB.new(template, nil, '%<>-')
puts output = renderer.result(TOPLEVEL_BINDING)