root / lib / server / confd.py @ b02c6bdf
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# Copyright (C) 2009, 2010 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Ganeti configuration daemon
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Ganeti-confd is a daemon to query master candidates for configuration values.
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It uses UDP+HMAC for authentication with a global cluster key.
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"""
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# pylint: disable=C0103
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# C0103: Invalid name ganeti-confd
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import os |
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import sys |
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import logging |
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import time |
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try:
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# pylint: disable=E0611
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from pyinotify import pyinotify |
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except ImportError: |
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import pyinotify |
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from optparse import OptionParser |
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from ganeti import asyncnotifier |
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from ganeti import confd |
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from ganeti.confd import server as confd_server |
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from ganeti import constants |
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from ganeti import errors |
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from ganeti import daemon |
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from ganeti import netutils |
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class ConfdAsyncUDPServer(daemon.AsyncUDPSocket): |
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"""The confd udp server, suitable for use with asyncore.
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"""
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def __init__(self, bind_address, port, processor): |
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"""Constructor for ConfdAsyncUDPServer
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@type bind_address: string
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@param bind_address: socket bind address
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@type port: int
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@param port: udp port
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@type processor: L{confd.server.ConfdProcessor}
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@param processor: ConfdProcessor to use to handle queries
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"""
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family = netutils.IPAddress.GetAddressFamily(bind_address) |
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daemon.AsyncUDPSocket.__init__(self, family)
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self.bind_address = bind_address
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self.port = port
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self.processor = processor
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self.bind((bind_address, port))
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logging.debug("listening on ('%s':%d)", bind_address, port)
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# this method is overriding a daemon.AsyncUDPSocket method
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def handle_datagram(self, payload_in, ip, port): |
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try:
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query = confd.UnpackMagic(payload_in) |
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except errors.ConfdMagicError, err:
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logging.debug(err) |
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return
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answer = self.processor.ExecQuery(query, ip, port)
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if answer is not None: |
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try:
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self.enqueue_send(ip, port, confd.PackMagic(answer))
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except errors.UdpDataSizeError:
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logging.error("Reply too big to fit in an udp packet.")
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class ConfdConfigurationReloader(object): |
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"""Logic to control when to reload the ganeti configuration
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This class is able to alter between inotify and polling, to rate-limit the
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number of reloads. When using inotify it also supports a fallback timed
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check, to verify that the reload hasn't failed.
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"""
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def __init__(self, processor, mainloop): |
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"""Constructor for ConfdConfigurationReloader
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@type processor: L{confd.server.ConfdProcessor}
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@param processor: ganeti-confd ConfdProcessor
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@type mainloop: L{daemon.Mainloop}
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@param mainloop: ganeti-confd mainloop
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"""
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self.processor = processor
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self.mainloop = mainloop
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self.polling = True |
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self.last_notification = 0 |
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# Asyncronous inotify handler for config changes
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cfg_file = constants.CLUSTER_CONF_FILE |
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self.wm = pyinotify.WatchManager()
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self.inotify_handler = asyncnotifier.SingleFileEventHandler(self.wm, |
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self.OnInotify,
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cfg_file) |
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notifier_class = asyncnotifier.ErrorLoggingAsyncNotifier |
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self.notifier = notifier_class(self.wm, self.inotify_handler) |
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self.timer_handle = None |
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self._EnableTimer()
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def OnInotify(self, notifier_enabled): |
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"""Receive an inotify notification.
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@type notifier_enabled: boolean
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@param notifier_enabled: whether the notifier is still enabled
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"""
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current_time = time.time() |
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time_delta = current_time - self.last_notification
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self.last_notification = current_time
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if time_delta < constants.CONFD_CONFIG_RELOAD_RATELIMIT:
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logging.debug("Moving from inotify mode to polling mode")
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self.polling = True |
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if notifier_enabled:
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self.inotify_handler.disable()
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if not self.polling and not notifier_enabled: |
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try:
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self.inotify_handler.enable()
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except errors.InotifyError:
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self.polling = True |
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try:
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reloaded = self.processor.reader.Reload()
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if reloaded:
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logging.info("Reloaded ganeti config")
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else:
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logging.debug("Skipped double config reload")
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except errors.ConfigurationError:
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self.DisableConfd()
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self.inotify_handler.disable()
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return
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# Reset the timer. If we're polling it will go to the polling rate, if
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# we're not it will delay it again to its base safe timeout.
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self._ResetTimer()
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def _DisableTimer(self): |
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if self.timer_handle is not None: |
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self.mainloop.scheduler.cancel(self.timer_handle) |
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self.timer_handle = None |
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def _EnableTimer(self): |
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if self.polling: |
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timeout = constants.CONFD_CONFIG_RELOAD_RATELIMIT |
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else:
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timeout = constants.CONFD_CONFIG_RELOAD_TIMEOUT |
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if self.timer_handle is None: |
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self.timer_handle = self.mainloop.scheduler.enter( |
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timeout, 1, self.OnTimer, []) |
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def _ResetTimer(self): |
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self._DisableTimer()
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self._EnableTimer()
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def OnTimer(self): |
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"""Function called when the timer fires
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"""
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self.timer_handle = None |
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reloaded = False
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was_disabled = False
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try:
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if self.processor.reader is None: |
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was_disabled = True
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self.EnableConfd()
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reloaded = True
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else:
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reloaded = self.processor.reader.Reload()
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except errors.ConfigurationError:
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self.DisableConfd(silent=was_disabled)
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return
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if self.polling and reloaded: |
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logging.info("Reloaded ganeti config")
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elif reloaded:
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# We have reloaded the config files, but received no inotify event. If
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# an event is pending though, we just happen to have timed out before
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# receiving it, so this is not a problem, and we shouldn't alert
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if not self.notifier.check_events() and not was_disabled: |
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logging.warning("Config file reload at timeout (inotify failure)")
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elif self.polling: |
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# We're polling, but we haven't reloaded the config:
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# Going back to inotify mode
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logging.debug("Moving from polling mode to inotify mode")
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self.polling = False |
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try:
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self.inotify_handler.enable()
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except errors.InotifyError:
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self.polling = True |
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else:
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logging.debug("Performed configuration check")
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self._EnableTimer()
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def DisableConfd(self, silent=False): |
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"""Puts confd in non-serving mode
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"""
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if not silent: |
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logging.warning("Confd is being disabled")
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self.processor.Disable()
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self.polling = False |
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self._ResetTimer()
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def EnableConfd(self): |
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self.processor.Enable()
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logging.warning("Confd is being enabled")
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self.polling = True |
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self._ResetTimer()
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def CheckConfd(_, args): |
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"""Initial checks whether to run exit with a failure.
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"""
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if args: # confd doesn't take any arguments |
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print >> sys.stderr, ("Usage: %s [-f] [-d] [-b ADDRESS]" % sys.argv[0]) |
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sys.exit(constants.EXIT_FAILURE) |
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# TODO: collapse HMAC daemons handling in daemons GenericMain, when we'll
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# have more than one.
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if not os.path.isfile(constants.CONFD_HMAC_KEY): |
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print >> sys.stderr, "Need HMAC key %s to run" % constants.CONFD_HMAC_KEY |
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sys.exit(constants.EXIT_FAILURE) |
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# TODO: once we have a cluster param specifying the address family
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# preference, we need to check if the requested options.bind_address does not
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# conflict with that. If so, we might warn or EXIT_FAILURE.
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def PrepConfd(options, _): |
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"""Prep confd function, executed with PID file held
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"""
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# TODO: clarify how the server and reloader variables work (they are
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# not used)
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# pylint: disable=W0612
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mainloop = daemon.Mainloop() |
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# Asyncronous confd UDP server
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processor = confd_server.ConfdProcessor() |
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try:
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processor.Enable() |
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except errors.ConfigurationError:
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# If enabling the processor has failed, we can still go on, but confd will
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# be disabled
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logging.warning("Confd is starting in disabled mode")
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server = ConfdAsyncUDPServer(options.bind_address, options.port, processor) |
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# Configuration reloader
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reloader = ConfdConfigurationReloader(processor, mainloop) |
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return mainloop
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def ExecConfd(options, args, prep_data): # pylint: disable=W0613 |
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"""Main confd function, executed with PID file held
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"""
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mainloop = prep_data |
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mainloop.Run() |
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def Main(): |
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"""Main function for the confd daemon.
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"""
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parser = OptionParser(description="Ganeti configuration daemon",
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usage="%prog [-f] [-d] [-b ADDRESS]",
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version="%%prog (ganeti) %s" %
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constants.RELEASE_VERSION) |
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daemon.GenericMain(constants.CONFD, parser, CheckConfd, PrepConfd, ExecConfd) |