json2csv.rb

require 'json'
require 'csv'

f = File.open('foo.json')
csv_out = CSV.generate do |csv|
  nodes = JSON.parse(f.read)

  #create header
  entry = nodes.first
  csv << ['node'] + entry[1].keys

  #output one record per node
  nodes.each do |node_name, facts|
    csv << [node_name] + facts.values
  end
end

puts csv_out