Source code for google.appengine.api.backendinfo

#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# 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.
#




"""
A library for working with BackendInfoExternal records, describing backends
configured for an application. Supports loading the records from backend.yaml.
"""








import os
import yaml
from yaml import representer

if os.environ.get('APPENGINE_RUNTIME') == 'python27':
  from google.appengine.api import validation
  from google.appengine.api import yaml_builder
  from google.appengine.api import yaml_listener
  from google.appengine.api import yaml_object
else:
  from google.appengine.api import validation
  from google.appengine.api import yaml_builder
  from google.appengine.api import yaml_listener
  from google.appengine.api import yaml_object

NAME_REGEX = r'(?!-)[a-z\d\-]{1,100}'
FILE_REGEX = r'(?!\^).*(?!\$).{1,256}'
CLASS_REGEX = r'^[bB](1|2|4|8|4_1G)$'
OPTIONS_REGEX = r'^[a-z, ]*$'
STATE_REGEX = r'^(START|STOP|DISABLED)$'


BACKENDS = 'backends'


NAME = 'name'
CLASS = 'class'
INSTANCES = 'instances'
OPTIONS = 'options'
PUBLIC = 'public'
DYNAMIC = 'dynamic'
FAILFAST = 'failfast'
MAX_CONCURRENT_REQUESTS = 'max_concurrent_requests'
START = 'start'

VALID_OPTIONS = frozenset([PUBLIC, DYNAMIC, FAILFAST])


STATE = 'state'

[docs]class BadConfig(Exception): """An invalid configuration was provided."""
[docs]class ListWithoutSort(list):
[docs] def sort(self): pass
[docs]class SortedDict(dict): def __init__(self, keys, data): super(SortedDict, self).__init__() self.keys = keys self.update(data)
[docs] def items(self): result = ListWithoutSort() for key in self.keys: if type(self.get(key)) != type(None): result.append((key, self.get(key))) return result
representer.SafeRepresenter.add_representer( SortedDict, representer.SafeRepresenter.represent_dict)
[docs]class BackendEntry(validation.Validated): """A backend entry describes a single backend.""" ATTRIBUTES = { NAME: NAME_REGEX, CLASS: validation.Optional(CLASS_REGEX), INSTANCES: validation.Optional(validation.TYPE_INT), MAX_CONCURRENT_REQUESTS: validation.Optional(validation.TYPE_INT), OPTIONS: validation.Optional(OPTIONS_REGEX), PUBLIC: validation.Optional(validation.TYPE_BOOL), DYNAMIC: validation.Optional(validation.TYPE_BOOL), FAILFAST: validation.Optional(validation.TYPE_BOOL), START: validation.Optional(FILE_REGEX), STATE: validation.Optional(STATE_REGEX), } def __init__(self, *args, **kwargs): super(BackendEntry, self).__init__(*args, **kwargs) self.Init()
[docs] def Init(self): if self.public: raise BadConfig("Illegal field: 'public'") if self.dynamic: raise BadConfig("Illegal field: 'dynamic'") if self.failfast: raise BadConfig("Illegal field: 'failfast'") self.ParseOptions() return self
[docs] def set_class(self, Class): """Setter for 'class', since an attribute reference is an error.""" self.Set(CLASS, Class)
[docs] def get_class(self): """Accessor for 'class', since an attribute reference is an error.""" return self.Get(CLASS)
[docs] def ToDict(self): """Returns a sorted dictionary representing the backend entry.""" self.ParseOptions().WriteOptions() result = super(BackendEntry, self).ToDict() return SortedDict([NAME, CLASS, INSTANCES, START, OPTIONS, MAX_CONCURRENT_REQUESTS, STATE], result)
[docs] def ParseOptions(self): """Parses the 'options' field and sets appropriate fields.""" if self.options: options = [option.strip() for option in self.options.split(',')] else: options = [] for option in options: if option not in VALID_OPTIONS: raise BadConfig('Unrecognized option: %s', option) self.public = PUBLIC in options self.dynamic = DYNAMIC in options self.failfast = FAILFAST in options return self
[docs] def WriteOptions(self): """Writes the 'options' field based on other settings.""" options = [] if self.public: options.append('public') if self.dynamic: options.append('dynamic') if self.failfast: options.append('failfast') if options: self.options = ', '.join(options) else: self.options = None return self
[docs]def LoadBackendEntry(backend_entry): """Parses a BackendEntry object from a string. Args: backend_entry: a backend entry, as a string Returns: A BackendEntry object. """ builder = yaml_object.ObjectBuilder(BackendEntry) handler = yaml_builder.BuilderHandler(builder) listener = yaml_listener.EventListener(handler) listener.Parse(backend_entry) entries = handler.GetResults() if len(entries) < 1: raise BadConfig('Empty backend configuration.') if len(entries) > 1: raise BadConfig('Multiple backend entries were found in configuration.') return entries[0].Init()
[docs]class BackendInfoExternal(validation.Validated): """BackendInfoExternal describes all backend entries for an application.""" ATTRIBUTES = { BACKENDS: validation.Optional(validation.Repeated(BackendEntry)), }
[docs]def LoadBackendInfo(backend_info, open_fn=None): """Parses a BackendInfoExternal object from a string. Args: backend_info: a backends stanza (list of backends) as a string open_fn: Function for opening files. Unused. Returns: A BackendInfoExternal object. """ builder = yaml_object.ObjectBuilder(BackendInfoExternal) handler = yaml_builder.BuilderHandler(builder) listener = yaml_listener.EventListener(handler) listener.Parse(backend_info) backend_info = handler.GetResults() if len(backend_info) < 1: return BackendInfoExternal(backends=[]) if len(backend_info) > 1: raise BadConfig("Only one 'backends' clause is allowed.") info = backend_info[0] if not info.backends: return BackendInfoExternal(backends=[]) for backend in info.backends: backend.Init() return info

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