gistfile1.rb

require 'rubygems'
require 'yaml'
require 'base64'
require 'openssl'
require 'net/https'
require "rexml/document"

class CloudfrontInvalidator
  def initialize(cf_id, *urls)
    @batch = "purging " + Time.now.to_s
    @cf_id = cf_id
    @url = URI.parse "https://cloudfront.amazonaws.com/2012-05-05/distribution/#{@cf_id}/invalidation"
    @urls = urls
    purge!
  end

private

  def purge!
    resp = post

    if resp.code == '201'
      puts "== OK purging #{@urls.join(",")}"
      puts "current jobs: #{get}"
    else
      puts "== ERROR \n#{resp.body}"
      puts "current jobs:\n#{get}"
    end
  end

  def response(method, data='')
    req = Net::HTTP.new(@url.host, @url.port)
    req.use_ssl = true
    req.verify_mode = OpenSSL::SSL::VERIFY_NONE
    req.send_request(method, @url.path, data, headers)
  end

  def post
    response 'POST', purge_list
  end

  def get
    resp_list response 'GET'
  end

  def resp_list(resp)
    list = []
    REXML::Document.new(resp.body).each_element("/InvalidationList/InvalidationSummary") do |el|
      list << el.elements["Id"].text + ":" + el.elements["Status"].text
    end
    list.join("\n")
  end

  def purge_list
    <<-EOF
      <InvalidationBatch>
        <Paths>
          <Quantity>#{@urls.size}</Quantity>
          <Items>
            #{@urls.map {|u| "<Path>" + u + "</Path>"}.join("")}
          </Items>
        </Paths>
        <CallerReference>#{@batch}</CallerReference>
      </InvalidationBatch>
    EOF
  end

  def headers
    s3_credentials = YAML::load_file(File.expand_path('../../config/s3.yml', __FILE__))
    abort s3_credentials.inspect unless s3_credentials[Rails.env.to_sym]
    s3_credentials = s3_credentials[Rails.env.to_sym]

    date = Time.now.strftime('%a, %d %b %Y %H:%M:%S %Z')

    signer = OpenSSL::Digest::Digest.new('sha1')
    digest = OpenSSL::HMAC.digest(signer, s3_credentials['secret_access_key'], date)

    auth = Base64.encode64(digest).strip

    { 'Date' => date,
      'Authorization'=> ["AWS #{s3_credentials['access_key_id']}:#{auth}"].join(',') }
  end
end