text: # Copyright 2011 OpenStack Foundation
  # Copyright 2013 IBM Corp.
  #
  #   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.
  
  from nova.api.openstack import common
  from nova.api.openstack import extensions
  from nova.api.openstack import wsgi
  from nova import compute
  
  ALIAS = "os-lock-server"
  
  authorize = extensions.os_compute_authorizer(ALIAS)
  
  
  class LockServerController(wsgi.Controller):
      def __init__(self, *args, **kwargs):
          super(LockServerController, self).__init__(*args, **kwargs)
          self.compute_api = compute.API(skip_policy_check=True)
  
      @wsgi.response(202)
      @extensions.expected_errors(404)
      @wsgi.action('lock')
      def _lock(self, req, id, body):
          """Lock a server instance."""
          context = req.environ['nova.context']
          authorize(context, action='lock')
          instance = common.get_instance(self.compute_api, context, id)
          self.compute_api.lock(context, instance)
  
      @wsgi.response(202)
      @extensions.expected_errors(404)
      @wsgi.action('unlock')
      def _unlock(self, req, id, body):
          """Unlock a server instance."""
          context = req.environ['nova.context']
          authorize(context, action='unlock')
          instance = common.get_instance(self.compute_api, context, id)
          if not self.compute_api.is_expected_locked_by(context, instance):
              authorize(context, target=instance,
                        action='unlock:unlock_override')
  
          self.compute_api.unlock(context, instance)
  
  
  class LockServer(extensions.V21APIExtensionBase):
      """Enable lock/unlock server actions."""
  
      name = "LockServer"
      alias = ALIAS
      version = 1
  
      def get_controller_extensions(self):
          controller = LockServerController()
          extension = extensions.ControllerExtension(self, 'servers', controller)
          return [extension]
  
      def get_resources(self):
          return []
  