Command line script to set the default root object of a cloudfront distribution

aws_cf_setroot.rb

require 'rubygems'
require 'hmac-sha1'
require 'net/https'
require 'base64'

s3_access='S3_ACCESS_KEY'
s3_secret='S3_SECRET_KEY'
cf_distribution='CLOUDFRONT_DISTRIBUTION_ID'

newobj = ARGV[0]

if newobj == nil
  puts "usage: aws_cf_setroot.rb index.html"
  exit
end

date = Time.now.utc
date = date.strftime("%a, %d %b %Y %H:%M:%S %Z")
digest = HMAC::SHA1.new(s3_secret)
digest << date

uri = URI.parse('https://cloudfront.amazonaws.com/2010-08-01/distribution/' + cf_distribution + '/config')

req = Net::HTTP::Get.new(uri.path)

req.initialize_http_header({
  'x-amz-date' => date,
  'Content-Type' => 'text/xml',
  'Authorization' => "AWS %s:%s" % [s3_access, Base64.encode64(digest.digest)]
})

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
res = http.request(req)

currentobj = /<DefaultRootObject>(.*?)<\/DefaultRootObject>/.match(res.body)[1]

if newobj == currentobj
  puts "'#{currentobj}' is already the DefaultRootObject"
  exit
end

etag = res.header['etag']

req = Net::HTTP::Put.new(uri.path)

req.initialize_http_header({
  'x-amz-date' => date,
  'Content-Type' => 'text/xml',
  'Authorization' => "AWS %s:%s" % [s3_access, Base64.encode64(digest.digest)],
  'If-Match' => etag
})

if currentobj == nil
  regex = /<\/DistributionConfig>/
  replace = "<DefaultRootObject>#{newobj}</DefaultRootObject></DistributionConfig>"
else
  regex = /<DefaultRootObject>(.*?)<\/DefaultRootObject>/
  replace = "<DefaultRootObject>#{newobj}</DefaultRootObject>"
end

req.body = res.body.gsub(regex, replace)

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
res = http.request(req)

puts res.code
puts res.body

Nice stuff. I think there is a small bug though. You should have something like the following for the first comers (when DefaultRootObject is not there yet). But then again, not a ruby expert.

objectset = /<DefaultRootObject>(.*?)<\/DefaultRootObject>/.match(res.body)

if objectset
  currentobj = objectset[1]
  if newobj == currentobj
    puts "'#{currentobj}' is already the DefaultRootObject"
    exit
  end
end