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#!/usr/bin/python
# Copyright 2016 Google Inc. All Rights Reserved.
#
# Licensed 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.
"""Manage clock skew after migration on a Google Compute Engine instance."""
import logging.handlers
import optparse
from google_compute_engine import config_manager
from google_compute_engine import constants
from google_compute_engine import file_utils
from google_compute_engine import logger
from google_compute_engine import metadata_watcher
from google_compute_engine.compat import distro_utils
LOCKFILE = constants.LOCALSTATEDIR + '/lock/google_clock_skew.lock'
class ClockSkewDaemon(object):
"""Responds to drift-token changes."""
drift_token = 'instance/virtual-clock/drift-token'
def __init__(self, debug=False):
"""Constructor.
Args:
debug: bool, True if debug output should write to the console.
"""
facility = logging.handlers.SysLogHandler.LOG_DAEMON
self.logger = logger.Logger(
name='google-clock-skew', debug=debug, facility=facility)
self.distro_utils = distro_utils.Utils(debug=debug)
self.watcher = metadata_watcher.MetadataWatcher(logger=self.logger)
try:
with file_utils.LockFile(LOCKFILE):
self.logger.info('Starting Google Clock Skew daemon.')
self.watcher.WatchMetadata(
self.HandleClockSync, metadata_key=self.drift_token,
recursive=False)
except (IOError, OSError) as e:
self.logger.warning(str(e))
def HandleClockSync(self, response):
"""Called when clock drift token changes.
Args:
response: string, the metadata response with the new drift token value.
"""
self.logger.info('Clock drift token has changed: %s.', response)
self.distro_utils.HandleClockSync(self.logger)
def main():
parser = optparse.OptionParser()
parser.add_option(
'-d', '--debug', action='store_true', dest='debug',
help='print debug output to the console.')
(options, _) = parser.parse_args()
instance_config = config_manager.ConfigManager()
if instance_config.GetOptionBool('Daemons', 'clock_skew_daemon'):
ClockSkewDaemon(debug=bool(options.debug))
if __name__ == '__main__':
main()
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