code: function getEC2IAMSecurityCredentials(role, callback) {
  		httpRequest({host: EC2_METADATA_HOST, path: SECURITY_CREDENTIALS_RESOURCE + role}, null, function(error, jsonStr, httpResponse) {
  			var credentials;
  			try {
  				credentials = JSON.parse(jsonStr);
  			} catch (parseError) {
  				if (!error) error = parseError;
  			}
  
  			callback(error, credentials, httpResponse);
  		});
  	}
docs: Gets the security credentials from the metadata service.
  
  @method getEC2IAMSecurityCredentials
  @private
  @param {String} role IAM role name.
  @param {Function} callback Callback function that receives the parsed credentials object returned by the metadata service.