#!/bin/env python

#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

import os
import subprocess
import sys

class Kerberos(object):

    def __init__(self):

        self._kinit =  os.getenv('KINITPATH')
        self._kinitopts =  os.getenv('KINITOPTS')
        self._keytab =  os.getenv('KEYTABPATH')
        self._krb_user =  os.getenv('KRB_USER')

        if self._kinit == None or self._kinitopts == None or self._keytab == None or self._krb_user == None:
            print "Please verify kerberos configuration, some environment variables are missing."
            sys.exit(1)

        self._kinit_args = [self._kinit,self._kinitopts,self._keytab,self._krb_user]

	def authenticate(self):

		kinit = subprocess.Popen(self._kinit_args, stderr = subprocess.PIPE)
		output,error = kinit.communicate()
		if not kinit.returncode == 0:
			if error:
				print error.rstrip()
				sys.exit(kinit.returncode)
		print "Successfully authenticated!"