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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 the retrieval and excution of metadata scripts."""
import contextlib
import logging.handlers
import optparse
import shutil
import tempfile
from google_compute_engine import config_manager
from google_compute_engine import logger
from google_compute_engine.metadata_scripts import script_executor
from google_compute_engine.metadata_scripts import script_retriever
@contextlib.contextmanager
def _CreateTempDir(prefix, run_dir=None):
"""Context manager for creating a temporary directory.
Args:
prefix: string, the prefix for the temporary directory.
run_dir: string, the base directory location of the temporary directory.
Yields:
string, the temporary directory created.
"""
temp_dir = tempfile.mkdtemp(prefix=prefix + '-', dir=run_dir)
try:
yield temp_dir
finally:
shutil.rmtree(temp_dir)
class ScriptManager(object):
"""A class for retrieving and executing metadata scripts."""
def __init__(
self, script_type, default_shell=None, run_dir=None, debug=False):
"""Constructor.
Args:
script_type: string, the metadata script type to run.
default_shell: string, the default shell to execute the script.
run_dir: string, the base directory location of the temporary directory.
debug: bool, True if debug output should write to the console.
"""
self.script_type = script_type
self.default_shell = default_shell
name = '%s-script' % self.script_type
facility = logging.handlers.SysLogHandler.LOG_DAEMON
self.logger = logger.Logger(name=name, debug=debug, facility=facility)
self.retriever = script_retriever.ScriptRetriever(self.logger, script_type)
self.executor = script_executor.ScriptExecutor(
self.logger, script_type, default_shell=default_shell)
self._RunScripts(run_dir=run_dir)
def _RunScripts(self, run_dir=None):
"""Retrieve metadata scripts and execute them.
Args:
run_dir: string, the base directory location of the temporary directory.
"""
with _CreateTempDir(self.script_type, run_dir=run_dir) as dest_dir:
try:
self.logger.info('Starting %s scripts.', self.script_type)
script_dict = self.retriever.GetScripts(dest_dir)
self.executor.RunScripts(script_dict)
finally:
self.logger.info('Finished running %s scripts.', self.script_type)
def main():
script_types = ('startup', 'shutdown')
parser = optparse.OptionParser()
parser.add_option(
'-d', '--debug', action='store_true', dest='debug',
help='print debug output to the console.')
parser.add_option(
'--script-type', dest='script_type', help='metadata script type.')
(options, _) = parser.parse_args()
if options.script_type and options.script_type.lower() in script_types:
script_type = options.script_type.lower()
else:
valid_args = ', '.join(script_types)
message = 'No valid argument specified. Options: [%s].' % valid_args
raise ValueError(message)
instance_config = config_manager.ConfigManager()
if instance_config.GetOptionBool('MetadataScripts', script_type):
ScriptManager(
script_type,
default_shell=instance_config.GetOptionString(
'MetadataScripts', 'default_shell'),
run_dir=instance_config.GetOptionString('MetadataScripts', 'run_dir'),
debug=bool(options.debug))
if __name__ == '__main__':
main()
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