text: #   Copyright 2011 OpenStack, LLC.
  #
  #   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.
  
  """The rescue mode extension."""
  
  import webob
  from webob import exc
  
  from nova.api.openstack import common
  from nova.api.openstack import extensions as exts
  from nova.api.openstack import wsgi
  from nova import compute
  from nova import exception
  from nova.openstack.common import cfg
  from nova.openstack.common import log as logging
  from nova import utils
  
  
  CONF = cfg.CONF
  LOG = logging.getLogger(__name__)
  authorize = exts.extension_authorizer('compute', 'rescue')
  
  
  class RescueController(wsgi.Controller):
      def __init__(self, *args, **kwargs):
          super(RescueController, self).__init__(*args, **kwargs)
          self.compute_api = compute.API()
  
      def _get_instance(self, context, instance_id):
          try:
              return self.compute_api.get(context, instance_id)
          except exception.InstanceNotFound:
              msg = _("Server not found")
              raise exc.HTTPNotFound(msg)
  
      @wsgi.action('rescue')
      @exts.wrap_errors
      def _rescue(self, req, id, body):
          """Rescue an instance."""
          context = req.environ["nova.context"]
          authorize(context)
  
          if body['rescue'] and 'adminPass' in body['rescue']:
              password = body['rescue']['adminPass']
          else:
              password = utils.generate_password()
  
          instance = self._get_instance(context, id)
          try:
              self.compute_api.rescue(context, instance,
                                      rescue_password=password)
          except exception.InstanceInvalidState as state_error:
              common.raise_http_conflict_for_instance_invalid_state(state_error,
                                                                    'rescue')
          return {'adminPass': password}
  
      @wsgi.action('unrescue')
      @exts.wrap_errors
      def _unrescue(self, req, id, body):
          """Unrescue an instance."""
          context = req.environ["nova.context"]
          authorize(context)
          instance = self._get_instance(context, id)
          try:
              self.compute_api.unrescue(context, instance)
          except exception.InstanceInvalidState as state_error:
              common.raise_http_conflict_for_instance_invalid_state(state_error,
                                                                    'unrescue')
          return webob.Response(status_int=202)
  
  
  class Rescue(exts.ExtensionDescriptor):
      """Instance rescue mode"""
  
      name = "Rescue"
      alias = "os-rescue"
      namespace = "http://docs.openstack.org/compute/ext/rescue/api/v1.1"
      updated = "2011-08-18T00:00:00+00:00"
  
      def get_controller_extensions(self):
          controller = RescueController()
          extension = exts.ControllerExtension(self, 'servers', controller)
          return [extension]
  