Generate nginx config file to skip cloudfront cidr addresses.

gen_cf_cidr.rb

#!/usr/bin/env ruby

require 'net/http'
require 'json'

url = URI.parse('https://ip-ranges.amazonaws.com/ip-ranges.json')
req = Net::HTTP::Get.new(url.to_s)
res = Net::HTTP.start(url.host, url.port, use_ssl: true) do |http|
  http.request(req)
end
json = JSON.parse(res.body)

print '# Amazon CloudFront IP Ranges'
print "# Generated at #{json['createDate']}"
json['prefixes'].select { |x| x['service'] == 'CLOUDFRONT' }.each do |y|
  puts "set_real_ip_from  #{y['ip_prefix']};"
end