\!/ KyuuKazami \!/

#!/usr/bin/python2.7
# Copyright (c) 2011 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
#
# Licensed under the Amazon Software License (the "License").  You may not use
# this file except in compliance with the License. A copy of the License is
# located at http://aws.amazon.com/asl or in the "license" file accompanying
# this file.  This file 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.

__version__     = '1.0'
__author__      = 'Amazon Web Services, Inc.'
__license__     = 'Amazon Software License (http://aws.amazon.com/asl/)'

import sys
import rpm
import yum
import syslog

def main():
    # Setup syslog
    syslog.openlog('check-system-update', syslog.LOG_PID)

    yb = yum.YumBase()

    # Disable plugin loading
    yb.disablePlugins()
    yb.preconf.init_plugins = False

    # We allow the user to pin their instance to a particular release
    # but this script is intended to notify of newer releases
    yb.preconf.releasever = 'latest'

    # Ensures that the cachedir exists and persists
    # Uses a temp dir if the normal one isn't writable
    if not yb.setCacheDir(reuse=True):
        syslog.syslog(syslog.LOG_WARNING, 'Unable to open cachedir: %s' % (yb.conf.cachedir))
        sys.exit(2)

    try:
        installed = yb.rpmdb.returnNewestByName('system-release')
        available = yb.pkgSack.returnNewestByName('system-release')
    except yum.Errors.YumBaseError, e:
        syslog.syslog(syslog.LOG_WARNING, 'Exception: %s' % e)
        sys.exit(2)

    # Compare only the version number
    # The epoch should not be changing (if it did some day we could update this script first)
    # The release could change for reasons as trivial as a rebuild
    if rpm.labelCompare(('0', installed[0].version, '0'), ('0', available[0].version, '0')) < 0:
        print "Amazon Linux version %s is available." % available[0].version
    else:
        sys.exit(1)

if __name__ == '__main__':
    main()