ganeti-confd 13.4 KB
Newer Older
Guido Trotter's avatar
Guido Trotter committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
#!/usr/bin/python
#

# Copyright (C) 2009, Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""Ganeti configuration daemon

Ganeti-confd is a daemon to query master candidates for configuration values.
It uses UDP+HMAC for authentication with a global cluster key.

"""

import os
import sys
import logging
import asyncore
import socket
import pyinotify
Guido Trotter's avatar
Guido Trotter committed
35
import time
36
import errno
Guido Trotter's avatar
Guido Trotter committed
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66

from optparse import OptionParser

from ganeti import constants
from ganeti import errors
from ganeti import daemon
from ganeti import ssconf
from ganeti.asyncnotifier import AsyncNotifier
from ganeti.confd.server import ConfdProcessor


class ConfdAsyncUDPServer(asyncore.dispatcher):
  """The confd udp server, suitable for use with asyncore.

  """
  def __init__(self, bind_address, port, processor):
    """Constructor for ConfdAsyncUDPServer

    @type bind_address: string
    @param bind_address: socket bind address ('' for all)
    @type port: int
    @param port: udp port
    @type processor: L{confd.server.ConfdProcessor}
    @param reader: ConfigReader to use to access the config

    """
    asyncore.dispatcher.__init__(self)
    self.bind_address = bind_address
    self.port = port
    self.processor = processor
67
    self.out_queue = []
Guido Trotter's avatar
Guido Trotter committed
68
69
70
71
72
73
74
75
76
77
78
79
80
81
    self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
    self.bind((bind_address, port))
    logging.debug("listening on ('%s':%d)" % (bind_address, port))

  # this method is overriding an asyncore.dispatcher method
  def handle_connect(self):
    # Python thinks that the first udp message from a source qualifies as a
    # "connect" and further ones are part of the same connection. We beg to
    # differ and treat all messages equally.
    pass

  # this method is overriding an asyncore.dispatcher method
  def handle_read(self):
    try:
82
83
84
85
86
87
88
89
90
      try:
        payload_in, address = self.recvfrom(4096)
      except socket.error, err:
        if err.errno == errno.EINTR:
          # we got a signal while trying to read. no need to do anything,
          # handle_read will be called again if there is data on the socket.
          return
        else:
          raise
Guido Trotter's avatar
Guido Trotter committed
91
92
93
      ip, port = address
      payload_out =  self.processor.ExecQuery(payload_in, ip, port)
      if payload_out is not None:
94
        self.out_queue.append((ip, port, payload_out))
Guido Trotter's avatar
Guido Trotter committed
95
96
97
98
99
100
101
102
    except:
      # we need to catch any exception here, log it, but proceed, because even
      # if we failed handling a single request, we still want the confd to
      # continue working.
      logging.error("Unexpected exception", exc_info=True)

  # this method is overriding an asyncore.dispatcher method
  def writable(self):
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
    # Only handle writes if we have something enqueued to write
    if self.out_queue:
      return True
    else:
      return False

  def handle_write(self):
    try:
      if not self.out_queue:
        logging.error("handle_write called with empty output queue")
        return
      (ip, port, payload) = self.out_queue[0]
      try:
        self.sendto(payload, 0, (ip, port))
      except socket.error, err:
        if err.errno == errno.EINTR:
          # we got a signal while trying to write. no need to do anything,
          # handle_write will be called again because we haven't emptied the
          # out_queue, and we'll try again
          return
        else:
          raise
      self.out_queue.pop(0)
    except:
      # we need to catch any exception here, log it, but proceed, because even
      # if we failed handling a single request, we still want the confd to
      # continue working.
      logging.error("Unexpected exception", exc_info=True)
Guido Trotter's avatar
Guido Trotter committed
131
132
133
134


class ConfdInotifyEventHandler(pyinotify.ProcessEvent):

135
  def __init__(self, watch_manager, callback,
Guido Trotter's avatar
Guido Trotter committed
136
137
138
139
140
               file=constants.CLUSTER_CONF_FILE):
    """Constructor for ConfdInotifyEventHandler

    @type watch_manager: L{pyinotify.WatchManager}
    @param watch_manager: ganeti-confd inotify watch manager
141
142
    @type callback: function accepting a boolean
    @param callback: function to call when an inotify event happens
Guido Trotter's avatar
Guido Trotter committed
143
144
145
146
147
148
    @type file: string
    @param file: config file to watch

    """
    # no need to call the parent's constructor
    self.watch_manager = watch_manager
149
    self.callback = callback
Guido Trotter's avatar
Guido Trotter committed
150
151
152
    self.mask = pyinotify.EventsCodes.IN_IGNORED | \
                pyinotify.EventsCodes.IN_MODIFY
    self.file = file
153
    self.watch_handle = None
Guido Trotter's avatar
Guido Trotter committed
154

155
156
  def enable(self):
    """Watch the given file
Guido Trotter's avatar
Guido Trotter committed
157
158

    """
159
160
161
    if self.watch_handle is None:
      result = self.watch_manager.add_watch(self.file, self.mask)
      if not self.file in result or result[self.file] <= 0:
162
        raise errors.InotifyError("Could not add inotify watcher")
163
164
165
166
167
168
169
170
171
172
173
      else:
        self.watch_handle = result[self.file]

  def disable(self):
    """Stop watching the given file

    """
    if self.watch_handle is not None:
      result = self.watch_manager.rm_watch(self.watch_handle)
      if result[self.watch_handle]:
        self.watch_handle = None
Guido Trotter's avatar
Guido Trotter committed
174
175
176
177
178
179
180
181
182

  def process_IN_IGNORED(self, event):
    # Due to the fact that we monitor just for the cluster config file (rather
    # than for the whole data dir) when the file is replaced with another one
    # (which is what happens normally in ganeti) we're going to receive an
    # IN_IGNORED event from inotify, because of the file removal (which is
    # contextual with the replacement). In such a case we need to create
    # another watcher for the "new" file.
    logging.debug("Received 'ignored' inotify event for %s" % event.path)
183
    self.watch_handle = None
Guido Trotter's avatar
Guido Trotter committed
184
185
186
187
188
189

    try:
      # Since the kernel believes the file we were interested in is gone, it's
      # not going to notify us of any other events, until we set up, here, the
      # new watch. This is not a race condition, though, since we're anyway
      # going to realod the file after setting up the new watch.
190
      self.callback(False)
Guido Trotter's avatar
Guido Trotter committed
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
    except errors.ConfdFatalError, err:
      logging.critical("Critical error, shutting down: %s" % err)
      sys.exit(constants.EXIT_FAILURE)
    except:
      # we need to catch any exception here, log it, but proceed, because even
      # if we failed handling a single request, we still want the confd to
      # continue working.
      logging.error("Unexpected exception", exc_info=True)

  def process_IN_MODIFY(self, event):
    # This gets called when the config file is modified. Note that this doesn't
    # usually happen in Ganeti, as the config file is normally replaced by a
    # new one, at filesystem level, rather than actually modified (see
    # utils.WriteFile)
    logging.debug("Received 'modify' inotify event for %s" % event.path)

    try:
208
      self.callback(True)
Guido Trotter's avatar
Guido Trotter committed
209
210
211
212
213
214
215
216
217
218
219
220
221
    except errors.ConfdFatalError, err:
      logging.critical("Critical error, shutting down: %s" % err)
      sys.exit(constants.EXIT_FAILURE)
    except:
      # we need to catch any exception here, log it, but proceed, because even
      # if we failed handling a single request, we still want the confd to
      # continue working.
      logging.error("Unexpected exception", exc_info=True)

  def process_default(self, event):
    logging.error("Received unhandled inotify event: %s" % event)


222
223
224
225
226
227
228
229
class ConfdConfigurationReloader(object):
  """Logic to control when to reload the ganeti configuration

  This class is able to alter between inotify and polling, to rate-limit the
  number of reloads. When using inotify it also supports a fallback timed
  check, to verify that the reload hasn't failed.

  """
230
  def __init__(self, processor, mainloop):
231
232
    """Constructor for ConfdConfigurationReloader

233
234
    @type processor: L{confd.server.ConfdProcessor}
    @param processor: ganeti-confd ConfdProcessor
Guido Trotter's avatar
Guido Trotter committed
235
236
    @type mainloop: L{daemon.Mainloop}
    @param mainloop: ganeti-confd mainloop
237
238

    """
239
    self.processor = processor
Guido Trotter's avatar
Guido Trotter committed
240
241
    self.mainloop = mainloop

Guido Trotter's avatar
Guido Trotter committed
242
    self.polling = True
Guido Trotter's avatar
Guido Trotter committed
243
    self.last_notification = 0
244
245
246

    # Asyncronous inotify handler for config changes
    self.wm = pyinotify.WatchManager()
247
248
249
    self.inotify_handler = ConfdInotifyEventHandler(self.wm, self.OnInotify)
    self.notifier = AsyncNotifier(self.wm, self.inotify_handler)

Guido Trotter's avatar
Guido Trotter committed
250
251
252
    self.timer_handle = None
    self._EnableTimer()

253
254
255
256
257
258
259
  def OnInotify(self, notifier_enabled):
    """Receive an inotify notification.

    @type notifier_enabled: boolean
    @param notifier_enabled: whether the notifier is still enabled

    """
Guido Trotter's avatar
Guido Trotter committed
260
261
262
263
264
265
266
267
    current_time = time.time()
    time_delta = current_time - self.last_notification
    self.last_notification = current_time

    if time_delta < constants.CONFD_CONFIG_RELOAD_RATELIMIT:
      logging.debug("Moving from inotify mode to polling mode")
      self.polling = True
      if notifier_enabled:
268
        self.inotify_handler.disable()
Guido Trotter's avatar
Guido Trotter committed
269
270

    if not self.polling and not notifier_enabled:
271
272
273
      try:
        self.inotify_handler.enable()
      except errors.InotifyError:
274
        self.polling = True
275
276

    try:
277
      reloaded = self.processor.reader.Reload()
278
279
280
281
282
      if reloaded:
        logging.info("Reloaded ganeti config")
      else:
        logging.debug("Skipped double config reload")
    except errors.ConfigurationError:
283
284
285
      self.DisableConfd()
      self.inotify_handler.disable()
      return
286

Guido Trotter's avatar
Guido Trotter committed
287
288
    # Reset the timer. If we're polling it will go to the polling rate, if
    # we're not it will delay it again to its base safe timeout.
289
    self._ResetTimer()
Guido Trotter's avatar
Guido Trotter committed
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305

  def _DisableTimer(self):
    if self.timer_handle is not None:
      self.mainloop.scheduler.cancel(self.timer_handle)
      self.timer_handle = None

  def _EnableTimer(self):
    if self.polling:
      timeout = constants.CONFD_CONFIG_RELOAD_RATELIMIT
    else:
      timeout = constants.CONFD_CONFIG_RELOAD_TIMEOUT

    if self.timer_handle is None:
      self.timer_handle = self.mainloop.scheduler.enter(
        timeout, 1, self.OnTimer, [])

306
307
308
309
  def _ResetTimer(self):
    self._DisableTimer()
    self._EnableTimer()

Guido Trotter's avatar
Guido Trotter committed
310
311
312
313
314
  def OnTimer(self):
    """Function called when the timer fires

    """
    self.timer_handle = None
315
316
    reloaded = False
    was_disabled = False
Guido Trotter's avatar
Guido Trotter committed
317
    try:
318
319
320
321
322
323
      if self.processor.reader is None:
        was_disabled = True
        self.EnableConfd()
        reloaded = True
      else:
        reloaded = self.processor.reader.Reload()
Guido Trotter's avatar
Guido Trotter committed
324
    except errors.ConfigurationError:
325
      self.DisableConfd(silent=was_disabled)
326
      return
Guido Trotter's avatar
Guido Trotter committed
327
328
329
330
331
332
333

    if self.polling and reloaded:
      logging.info("Reloaded ganeti config")
    elif reloaded:
      # We have reloaded the config files, but received no inotify event.  If
      # an event is pending though, we just happen to have timed out before
      # receiving it, so this is not a problem, and we shouldn't alert
334
      if not self.notifier.check_events() and not was_disabled:
Guido Trotter's avatar
Guido Trotter committed
335
336
337
338
339
340
        logging.warning("Config file reload at timeout (inotify failure)")
    elif self.polling:
      # We're polling, but we haven't reloaded the config:
      # Going back to inotify mode
      logging.debug("Moving from polling mode to inotify mode")
      self.polling = False
341
342
343
344
      try:
        self.inotify_handler.enable()
      except errors.InotifyError:
        self.polling = True
Guido Trotter's avatar
Guido Trotter committed
345
346
347
348
    else:
      logging.debug("Performed configuration check")

    self._EnableTimer()
349

350
  def DisableConfd(self, silent=False):
351
352
353
    """Puts confd in non-serving mode

    """
354
355
    if not silent:
      logging.warning("Confd is being disabled")
356
357
358
359
360
361
362
363
364
365
    self.processor.Disable()
    self.polling = False
    self._ResetTimer()

  def EnableConfd(self):
    self.processor.Enable()
    logging.warning("Confd is being enabled")
    self.polling = True
    self._ResetTimer()

366

Michael Hanselmann's avatar
Michael Hanselmann committed
367
368
def CheckConfd(options, args):
  """Initial checks whether to run exit with a failure.
Guido Trotter's avatar
Guido Trotter committed
369
370
371
372
373
374
375
376
377

  """
  # TODO: collapse HMAC daemons handling in daemons GenericMain, when we'll
  # have more than one.
  if not os.path.isfile(constants.HMAC_CLUSTER_KEY):
    print >> sys.stderr, "Need HMAC key %s to run" % constants.HMAC_CLUSTER_KEY
    sys.exit(constants.EXIT_FAILURE)


Michael Hanselmann's avatar
Michael Hanselmann committed
378
379
def ExecConfd(options, args):
  """Main confd function, executed with PID file held
Guido Trotter's avatar
Guido Trotter committed
380
381

  """
382
383
  mainloop = daemon.Mainloop()

Guido Trotter's avatar
Guido Trotter committed
384
  # Asyncronous confd UDP server
385
  processor = ConfdProcessor()
386
387
388
  try:
    processor.Enable()
  except errors.ConfigurationError:
389
390
    # If enabling the processor has failed, we can still go on, but confd will
    # be disabled
391
    logging.warning("Confd is starting in disabled mode")
392
    pass
Guido Trotter's avatar
Guido Trotter committed
393
394
  server = ConfdAsyncUDPServer(options.bind_address, options.port, processor)

395
  # Configuration reloader
396
  reloader = ConfdConfigurationReloader(processor, mainloop)
397
398

  mainloop.Run()
Guido Trotter's avatar
Guido Trotter committed
399
400
401
402
403
404
405
406
407
408
409
410
411
412


def main():
  """Main function for the confd daemon.

  """
  parser = OptionParser(description="Ganeti configuration daemon",
                        usage="%prog [-f] [-d] [-b ADDRESS]",
                        version="%%prog (ganeti) %s" %
                        constants.RELEASE_VERSION)

  dirs = [(val, constants.RUN_DIRS_MODE) for val in constants.SUB_RUN_DIRS]
  dirs.append((constants.LOG_OS_DIR, 0750))
  dirs.append((constants.LOCK_DIR, 1777))
Michael Hanselmann's avatar
Michael Hanselmann committed
413
  daemon.GenericMain(constants.CONFD, parser, dirs, CheckConfd, ExecConfd)
Guido Trotter's avatar
Guido Trotter committed
414
415


Michael Hanselmann's avatar
Michael Hanselmann committed
416
if __name__ == "__main__":
Guido Trotter's avatar
Guido Trotter committed
417
  main()