synapse-product/synapse/util/module_loader.py

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# -*- coding: utf-8 -*-
# Copyright 2017 New Vector 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 importlib
import importlib.util
import itertools
from typing import Any, Iterable, Tuple, Type
import jsonschema
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from synapse.config._base import ConfigError
from synapse.config._util import json_error_to_config_error
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def load_module(provider: dict, config_path: Iterable[str]) -> Tuple[Type, Any]:
""" Loads a synapse module with its config
Args:
provider: a dict with keys 'module' (the module name) and 'config'
(the config dict).
config_path: the path within the config file. This will be used as a basis
for any error message.
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Returns
Tuple of (provider class, parsed config object)
"""
modulename = provider.get("module")
if not isinstance(modulename, str):
raise ConfigError(
"expected a string", path=itertools.chain(config_path, ("module",))
)
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# We need to import the module, and then pick the class out of
# that, so we split based on the last dot.
module, clz = modulename.rsplit(".", 1)
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module = importlib.import_module(module)
provider_class = getattr(module, clz)
module_config = provider.get("config")
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try:
provider_config = provider_class.parse_config(module_config)
except jsonschema.ValidationError as e:
raise json_error_to_config_error(e, itertools.chain(config_path, ("config",)))
except ConfigError as e:
raise _wrap_config_error(
"Failed to parse config for module %r" % (modulename,),
prefix=itertools.chain(config_path, ("config",)),
e=e,
)
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except Exception as e:
raise ConfigError(
"Failed to parse config for module %r" % (modulename,),
path=itertools.chain(config_path, ("config",)),
) from e
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return provider_class, provider_config
def load_python_module(location: str):
"""Load a python module, and return a reference to its global namespace
Args:
location (str): path to the module
Returns:
python module object
"""
spec = importlib.util.spec_from_file_location(location, location)
if spec is None:
raise Exception("Unable to load module at %s" % (location,))
mod = importlib.util.module_from_spec(spec)
spec.loader.exec_module(mod) # type: ignore
return mod
def _wrap_config_error(
msg: str, prefix: Iterable[str], e: ConfigError
) -> "ConfigError":
"""Wrap a relative ConfigError with a new path
This is useful when we have a ConfigError with a relative path due to a problem
parsing part of the config, and we now need to set it in context.
"""
path = prefix
if e.path:
path = itertools.chain(prefix, e.path)
e1 = ConfigError(msg, path)
# ideally we would set the 'cause' of the new exception to the original exception;
# however now that we have merged the path into our own, the stringification of
# e will be incorrect, so instead we create a new exception with just the "msg"
# part.
e1.__cause__ = Exception(e.msg)
e1.__cause__.__cause__ = e.__cause__
return e1