neutron/agent/linux/ip_monitor.py

   1 # Copyright 2015 Red Hat, Inc.
   2 # All Rights Reserved.
   3 #
   4 #    Licensed under the Apache License, Version 2.0 (the "License"); you may
   5 #    not use this file except in compliance with the License. You may obtain
   6 #    a copy of the License at
   7 #
   8 #         http://www.apache.org/licenses/LICENSE-2.0
   9 #
  10 #    Unless required by applicable law or agreed to in writing, software
  11 #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  12 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  13 #    License for the specific language governing permissions and limitations
  14 #    under the License.
  15
  16 from oslo_log import log as logging
  17 from oslo_utils import excutils
  18
  19 from neutron._i18n import _LE
  20 from neutron.agent.linux import async_process
  21 from neutron.agent.linux import ip_lib
  22
  23 LOG = logging.getLogger(__name__)
  24
  25
  26 class IPMonitorEvent(object):
  27     def __init__(self, line, added, interface, cidr):
  28         self.line = line
  29         self.added = added
  30         self.interface = interface
  31         self.cidr = cidr
  32
  33     def __str__(self):
  34         return self.line
  35
  36     @classmethod
  37     def from_text(cls, line):
  38         route = line.split()
  39
  40         try:
  41             first_word = route[0]
  42         except IndexError:
  43             with excutils.save_and_reraise_exception():
  44                 LOG.error(_LE('Unable to parse route "%s"'), line)
  45
  46         added = (first_word != 'Deleted')
  47         if not added:
  48             route = route[1:]
  49
  50         try:
  51             interface = ip_lib.remove_interface_suffix(route[1])
  52             cidr = route[3]
  53         except IndexError:
  54             with excutils.save_and_reraise_exception():
  55                 LOG.error(_LE('Unable to parse route "%s"'), line)
  56
  57         return cls(line, added, interface, cidr)
  58
  59
  60 class IPMonitor(async_process.AsyncProcess):
  61     """Wrapper over `ip monitor address`.
  62
  63     To monitor and react indefinitely:
  64         m = IPMonitor(namespace='tmp', root_as_root=True)
  65         m.start()
  66         for iterable in m:
  67             event = IPMonitorEvent.from_text(iterable)
  68             print(event, event.added, event.interface, event.cidr)
  69     """
  70
  71     def __init__(self,
  72                  namespace=None,
  73                  run_as_root=True,
  74                  respawn_interval=None):
  75         super(IPMonitor, self).__init__(['ip', '-o', 'monitor', 'address'],
  76                                         run_as_root=run_as_root,
  77                                         respawn_interval=respawn_interval,
  78                                         namespace=namespace)
  79
  80     def __iter__(self):
  81         return self.iter_stdout(block=True)
  82
  83     def start(self):
  84         super(IPMonitor, self).start(block=True)
  85
  86     def stop(self):
  87         super(IPMonitor, self).stop(block=True)