cloudfront-invalidator.rb

# purge cloudfront buckets usage
#
#   $ invalidator cloudfront_id [urls]
#
# requires /etc/aws.conf to be a yaml of you aws credentials like:
# 
# access_key: [redacted]
# secret_access_key: [redacted]


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

class CloudInvalidator
  def initialize(cf_id, *urls)
    @batch = "purging " + Time.now.to_s
    @cf_id = cf_id
    @url   = URI.parse "https://cloudfront.amazonaws.com/2010-11-01/distribution/#{@cf_id}/invalidation"
    @urls  = urls
    purge!
  end

private

  def purge!
    resp = post

    if resp.code == '201'
      puts "== \x1b[32mOK \x1b[0mpurging #{@urls.join(",")}"
      puts "current jobs: #{get}"
    else
      puts "== \x1b[31mERROR\x1b[0m\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
    "<InvalidationBatch>#{@urls.map {|u| "<Path>" + u + "</Path>"}.join("")}<CallerReference>#{@batch}</CallerReference></InvalidationBatch>"
  end


  def headers
    creds = YAML::load_file '/etc/aws.conf'
    date = Time.now.strftime('%a, %d %b %Y %H:%M:%S %Z')

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

    auth = Base64.encode64(digest).strip

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

if __NAME__ = $0
  cf_id  = ARGV.shift
  CloudInvalidator.new cf_id, *ARGV
end