class Gem::S3URISigner

def ec2_metadata_credentials_json
  require 'net/http'
  require 'rubygems/request'
  require 'rubygems/request/connection_pools'
  require 'json'
  iam_info = ec2_metadata_request(EC2_IAM_INFO)
  # Expected format: arn:aws:iam::<id>:instance-profile/<role_name>
  role_name = iam_info['InstanceProfileArn'].split('/').last
  ec2_metadata_request(EC2_IAM_SECURITY_CREDENTIALS + role_name)
end