text: # Copyright 2017 Huawei Technologies Co.,LTD.
  #
  # 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.
  
  import time
  
  import nova.compute.resource_tracker
  from nova import exception
  from nova import test
  from nova.tests import fixtures as nova_fixtures
  from nova.tests.functional import fixtures as func_fixtures
  from nova.tests.unit import cast_as_call
  from nova.tests.unit import fake_network
  import nova.tests.unit.image.fake
  from nova.tests.unit import policy_fixture
  from nova.virt import fake
  
  
  class TestRetryBetweenComputeNodeBuilds(test.TestCase):
      """This tests a regression introduced in the Ocata release.
  
      In Ocata we started building instances in conductor for cells v2. That
      uses a new "schedule_and_build_instances" in the ConductorManager rather
      than the old "build_instances" method and duplicates a lot of the same
      logic, but it missed populating the "retry" value in the scheduler filter
      properties. As a result, failures to build an instance on a compute node
      which would normally result in a retry of the build on another compute
      node are not actually happening.
      """
  
      def setUp(self):
          super(TestRetryBetweenComputeNodeBuilds, self).setUp()
  
          self.useFixture(policy_fixture.RealPolicyFixture())
  
          # The NeutronFixture is needed to stub out validate_networks in API.
          self.useFixture(nova_fixtures.NeutronFixture(self))
  
          # This stubs out the network allocation in compute.
          fake_network.set_stub_network_methods(self)
  
          # We need the computes reporting into placement for the filter
          # scheduler to pick a host.
          self.useFixture(func_fixtures.PlacementFixture())
  
          api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
              api_version='v2.1'))
          # The admin API is used to get the server details to verify the
          # host on which the server was built.
          self.admin_api = api_fixture.admin_api
  
          # the image fake backend needed for image discovery
          nova.tests.unit.image.fake.stub_out_image_service(self)
  
          self.start_service('conductor')
          self.start_service('consoleauth')
  
          # We start two compute services because we're going to fake one
          # of them to fail the build so we can trigger the retry code.
          # set_nodes() is needed to have each compute service return a
          # different nodename, so we get two hosts in the list of candidates
          # for scheduling. Otherwise both hosts will have the same default
          # nodename "fake-mini". The host passed to start_service controls the
          # "host" attribute and set_nodes() sets the "nodename" attribute.
          # We set_nodes() to make host and nodename the same for each compute.
          fake.set_nodes(['host1'])
          self.addCleanup(fake.restore_nodes)
          self.start_service('compute', host='host1')
          fake.set_nodes(['host2'])
          self.start_service('compute', host='host2')
  
          self.scheduler_service = self.start_service('scheduler')
  
          self.useFixture(cast_as_call.CastAsCall(self))
  
          self.image_id = self.admin_api.get_images()[0]['id']
          self.flavor_id = self.admin_api.get_flavors()[0]['id']
  
          # This is our flag that we set when we hit the first host and
          # made it fail.
          self.failed_host = None
          self.attempts = 0
  
          # We can't stub nova.compute.claims.Claims.__init__ because there is
          # a race where nova.compute.claims.NopClaim will be used instead,
          # see for details:
          #   https://github.com/openstack/nova/blob/bb02d11/nova/compute/
          #   resource_tracker.py#L121-L130
          real_instance_claim =\
                  nova.compute.resource_tracker.ResourceTracker.instance_claim
  
          def fake_instance_claim(_self, *args, **kwargs):
              self.attempts += 1
              if self.failed_host is None:
                  # Set the failed_host value to the ResourceTracker.host value.
                  self.failed_host = _self.host
                  raise exception.ComputeResourcesUnavailable(
                      reason='failure on host %s' % _self.host)
              return real_instance_claim(_self, *args, **kwargs)
  
          self.stub_out(
              'nova.compute.resource_tracker.ResourceTracker.instance_claim',
              fake_instance_claim)
  
      def _wait_for_instance_status(self, server_id, status):
          timeout = 0.0
          server = self.admin_api.get_server(server_id)
          while server['status'] != status and timeout < 10.0:
              time.sleep(.1)
              timeout += .1
              server = self.admin_api.get_server(server_id)
          if server['status'] != status:
              self.fail('Timed out waiting for server %s to have status: %s. '
                        'Current status: %s. Build attempts: %s' %
                        (server_id, status, server['status'], self.attempts))
          return server
  
      def test_retry_build_on_compute_error(self):
          """Tests the retry operation between compute nodes when one fails.
  
          This tests the scenario that we have two compute services and we
          try to build a single server. The test is setup such that the
          scheduler picks the first host which we mock out to fail the claim.
          This should then trigger a retry to the second host.
          """
          # Now that the bug is fixed, we should assert that the server goes to
          # ACTIVE status and is on the second host after the retry operation.
          server = dict(
              name='retry-test',
              imageRef=self.image_id,
              flavorRef=self.flavor_id)
          server = self.admin_api.post_server({'server': server})
          self.addCleanup(self.admin_api.delete_server, server['id'])
          server = self._wait_for_instance_status(server['id'], 'ACTIVE')
  
          # Assert that the host is not the failed host.
          self.assertNotEqual(self.failed_host,
                              server['OS-EXT-SRV-ATTR:host'])
  
          # Assert that we retried.
          self.assertEqual(2, self.attempts)
  
  
  class TestRetryBetweenComputeNodeBuildsNoAllocations(
          TestRetryBetweenComputeNodeBuilds):
      """Tests the reschedule scenario using a scheduler driver which does
      not use Placement.
      """
      def setUp(self):
          super(TestRetryBetweenComputeNodeBuildsNoAllocations, self).setUp()
          # We need to mock the FilterScheduler to not use Placement so that
          # allocations won't be created during scheduling.
          self.scheduler_service.manager.driver.USES_ALLOCATION_CANDIDATES = \
              False
  