Facter fact code and a python script to read some user defined AWS EC2 instance properties during provisioning.

ec2-user-data-parser.py

# Invocation example:
#
# $ curl -s "http://169.254.169.254/latest/user-data/" > /tmp/test.yaml
# $ cat /tmp/test.yaml
# instance:
#     flavor: application-server
# $ abc=$(cat /tmp/test.yaml | python ec2-user-data-parser.py instance flavor)
# $ echo $abc
# application-server
# $


import sys
import yaml

if __name__ == '__main__':
        contents = sys.stdin.read()
        document = yaml.load(contents)
        for key in sys.argv[1:]:
                try:
                        document = document[key]
                except KeyError:
                        sys.exit(1)
        sys.stdout.write(str(document))
        sys.stdout.flush()
        sys.exit(0)

server_flavor.rb

# server_flavor.rb

Facter.add("server_flavor") do
  setcode do
    Facter::Util::Resolution.exec('/usr/bin/curl --silent "http://169.254.169.254/latest/user-data/" | /usr/bin/python /root/tools/ec2-user-data-parser.py instance flavor')
  end
end