def construct(cls: Type[TF], env: Environment) -> TF:
"""
Constructs concrete infrastructure factory for given
named application. Reads and resolves persistence
topic from environment variable 'PERSISTENCE_MODULE'.
"""
factory_cls: Type[TF]
# noinspection SpellCheckingInspection
topic = (
env.get(
"INFRASTRUCTURE_FACTORY", # Legacy.
"",
) or env.get(
"FACTORY_TOPIC", # Legacy.
"",
) or env.get(
cls.PERSISTENCE_MODULE,
"eventsourcing.popo:Factory",
))
try:
obj: Union[Type[TF], ModuleType] = resolve_topic(topic)
except TopicError as e:
raise EnvironmentError(
"Failed to resolve persistence module topic: "
f"'{topic}' from environment "
f"variable '{cls.PERSISTENCE_MODULE}'") from e
if isinstance(obj, ModuleType):
# Find the factory in the module.
factory_classes: List[Type[TF]] = []
for member in obj.__dict__.values():
if (isinstance(member, type)
and issubclass(member, InfrastructureFactory)
and member != InfrastructureFactory):
factory_classes.append(cast(Type[TF], member))
if len(factory_classes) == 1:
factory_cls = factory_classes[0]
else:
raise AssertionError(
f"Found {len(factory_classes)} infrastructure factory classes in"
f" '{topic}', expected 1.")
elif isinstance(obj, type) and issubclass(obj, InfrastructureFactory):
factory_cls = obj
else:
raise AssertionError(
f"Not an infrastructure factory class or module: {topic}")
return factory_cls(env=env)
def __init__(self, environment: Environment):
"""
Initialises AES cipher with ``cipher_key``.
:param str cipher_key: 16, 24, or 32 bytes encoded as base64
"""
cipher_key = environment.get(self.CIPHER_KEY)
if not cipher_key:
raise EnvironmentError(f"'{self.CIPHER_KEY}' not set in env")
key = b64decode(cipher_key.encode("utf8"))
AESCipher.check_key_size(len(key))
self.key = key