7c615c9f49
This branch adds the ability to define a local JSON file that will hold configuration information that the scheduler can use. This dict will be passed into the filter and weighing functions so that Operations can tweak the scheduler without having to bring down the scheduler service. Currently the polling time on the file is hardcoded at 5 minutes, but certainly this could be made into a flag. Next update will be to remove the host_filter and weighing_functions flags and fix the scheduler to get these values from the config file. Change-Id: Ia2487e933483761276058689fad84564d96a451e
99 lines
3.3 KiB
Python
99 lines
3.3 KiB
Python
# Copyright (c) 2011 Openstack, LLC.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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SchedulerOptions monitors a local .json file for changes and loads
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it if needed. This file is converted to a data structure and passed
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into the filtering and weighing functions which can use it for
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dynamic configuration.
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"""
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import datetime
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import json
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import os
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from nova import flags
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from nova import log as logging
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FLAGS = flags.FLAGS
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flags.DEFINE_string('scheduler_json_config_location',
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'',
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'Absolute path to scheduler configuration JSON file.')
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LOG = logging.getLogger('nova.scheduler.scheduler_options')
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class SchedulerOptions(object):
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"""
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SchedulerOptions monitors a local .json file for changes and loads it
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if needed. This file is converted to a data structure and passed into
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the filtering and weighing functions which can use it for dynamic
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configuration.
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"""
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def __init__(self):
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super(SchedulerOptions, self).__init__()
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self.data = {}
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self.last_modified = None
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self.last_checked = None
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def _get_file_handle(self, filename):
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"""Get file handle. Broken out for testing."""
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return open(filename)
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def _get_file_timestamp(self, filename):
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"""Get the last modified datetime. Broken out for testing."""
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try:
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return os.path.getmtime(filename)
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except os.error, e:
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LOG.exception(_("Could not stat scheduler options file "
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"%(filename)s: '%(e)s'", locals()))
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raise
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def _load_file(self, handle):
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"""Decode the JSON file. Broken out for testing."""
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try:
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return json.load(handle)
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except ValueError, e:
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LOG.exception(_("Could not decode scheduler options: "
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"'%(e)s'") % locals())
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return {}
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def _get_time_now(self):
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"""Get current UTC. Broken out for testing."""
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return datetime.datetime.utcnow()
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def get_configuration(self, filename=None):
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"""Check the json file for changes and load it if needed."""
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if not filename:
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filename = FLAGS.scheduler_json_config_location
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if not filename:
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return self.data
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if self.last_checked:
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now = self._get_time_now()
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if now - self.last_checked < datetime.timedelta(minutes=5):
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return self.data
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last_modified = self._get_file_timestamp(filename)
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if not last_modified or not self.last_modified or \
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last_modified > self.last_modified:
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self.data = self._load_file(self._get_file_handle(filename))
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self.last_modified = last_modified
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if not self.data:
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self.data = {}
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return self.data
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