Hack to get ec2 tags to facter. Depends on aws-cli (https://github.com/aws/aws-cli), jq (http://stedolan.github.io/jq/) and the JSON RubyGem (http://rubygems.org/gems/json)

ec2tags.rb

require 'facter'
require 'json'

if Facter.value("ec2_instance_id") != nil
 instance_id = Facter.value("ec2_instance_id")
 region = Facter.value("ec2_placement_availability_zone")[0..-2]
 tags = Facter::Util::Resolution.exec("aws ec2 describe-tags --filters \"name=resource-id,values=#{instance_id}\" --region #{region} | jq '[.Tags[] | {key: .Key, value: .Value}]'")
 
 parsed_tags = JSON.parse(tags)
 parsed_tags.each do |tag|
  fact = "ec2_tag_#{tag["key"]}"
  Facter.add(fact) { setcode { tag["value"] } }
 end
end