Coverage for nova/scheduler/filters/__init__.py: 91%

1# Copyright (c) 2011 OpenStack Foundation 

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""" 

17Scheduler host filters 

18""" 

19from oslo_log import log as logging 

20 

21from nova import filters 

22 

23LOG = logging.getLogger(__name__) 

24 

25 

26class BaseHostFilter(filters.BaseFilter): 

27 """Base class for host filters.""" 

28 

29 # This is set to True if this filter should be run for rebuild. 

30 # For example, with rebuild, we need to ask the scheduler if the 

31 # existing host is still legit for a rebuild with the new image and 

32 # other parameters. We care about running policy filters (i.e. 

33 # ImagePropertiesFilter) but not things that check usage on the 

34 # existing compute node, etc. 

35 # This also means that filters marked with RUN_ON_REBUILD = True cannot 

36 # filter on allocation candidates or need to handle the rebuild case 

37 # specially. 

38 RUN_ON_REBUILD = False 

39 

40 def _filter_one(self, obj, spec): 

41 """Return True if the object passes the filter, otherwise False.""" 

42 # Do this here so we don't get scheduler.filters.utils 

43 from nova.scheduler import utils 

44 if not self.RUN_ON_REBUILD and utils.request_is_rebuild(spec): 44 ↛ 46line 44 didn't jump to line 46 because the condition on line 44 was never true

45 # If we don't filter, default to passing the host. 

46 return True 

47 else: 

48 # We are either a rebuild filter, in which case we always run, 

49 # or this request is not rebuild in which case all filters 

50 # should run. 

51 return self.host_passes(obj, spec) 

52 

53 def host_passes(self, host_state, filter_properties): 

54 """Return True if the HostState passes the filter, otherwise False. 

55 Override this in a subclass. 

56 """ 

57 raise NotImplementedError() 

58 

59 

60class CandidateFilterMixin: 

61 """Mixing that helps to implement a Filter that needs to filter host by 

62 Placement allocation candidates. 

63 """ 

64 

65 def filter_candidates(self, host_state, filter_func): 

66 """Checks still viable allocation candidates by the filter_func and 

67 keep only those that are passing it. 

68 

69 :param host_state: HostState object holding the list of still viable 

70 allocation candidates 

71 :param filter_func: A callable that takes an allocation candidate and 

72 returns a True like object if the candidate passed the filter or a 

73 False like object if it doesn't. 

74 """ 

75 good_candidates = [] 

76 for candidate in host_state.allocation_candidates: 

77 LOG.debug( 

78 f'{self.__class__.__name__} tries allocation candidate: ' 

79 f'{candidate}', 

80 ) 

81 if filter_func(candidate): 

82 LOG.debug( 

83 f'{self.__class__.__name__} accepted allocation ' 

84 f'candidate: {candidate}', 

85 ) 

86 good_candidates.append(candidate) 

87 else: 

88 LOG.debug( 

89 f'{self.__class__.__name__} rejected allocation ' 

90 f'candidate: {candidate}', 

91 ) 

92 

93 host_state.allocation_candidates = good_candidates 

94 return good_candidates 

95 

96 

97class HostFilterHandler(filters.BaseFilterHandler): 

98 def __init__(self): 

99 super(HostFilterHandler, self).__init__(BaseHostFilter) 

100 

101 

102def all_filters(): 

103 """Return a list of filter classes found in this directory. 

104 

105 This method is used as the default for available scheduler filters 

106 and should return a list of all filter classes available. 

107 """ 

108 return HostFilterHandler().get_all_classes()