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338 lines
12 KiB
Python
338 lines
12 KiB
Python
2 years ago
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import errno
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import json
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import os
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import types
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import typing as t
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from werkzeug.utils import import_string
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class ConfigAttribute:
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"""Makes an attribute forward to the config"""
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def __init__(self, name: str, get_converter: t.Optional[t.Callable] = None) -> None:
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self.__name__ = name
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self.get_converter = get_converter
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def __get__(self, obj: t.Any, owner: t.Any = None) -> t.Any:
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if obj is None:
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return self
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rv = obj.config[self.__name__]
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if self.get_converter is not None:
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rv = self.get_converter(rv)
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return rv
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def __set__(self, obj: t.Any, value: t.Any) -> None:
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obj.config[self.__name__] = value
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class Config(dict):
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"""Works exactly like a dict but provides ways to fill it from files
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or special dictionaries. There are two common patterns to populate the
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config.
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Either you can fill the config from a config file::
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app.config.from_pyfile('yourconfig.cfg')
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Or alternatively you can define the configuration options in the
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module that calls :meth:`from_object` or provide an import path to
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a module that should be loaded. It is also possible to tell it to
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use the same module and with that provide the configuration values
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just before the call::
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DEBUG = True
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SECRET_KEY = 'development key'
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app.config.from_object(__name__)
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In both cases (loading from any Python file or loading from modules),
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only uppercase keys are added to the config. This makes it possible to use
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lowercase values in the config file for temporary values that are not added
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to the config or to define the config keys in the same file that implements
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the application.
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Probably the most interesting way to load configurations is from an
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environment variable pointing to a file::
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app.config.from_envvar('YOURAPPLICATION_SETTINGS')
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In this case before launching the application you have to set this
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environment variable to the file you want to use. On Linux and OS X
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use the export statement::
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export YOURAPPLICATION_SETTINGS='/path/to/config/file'
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On windows use `set` instead.
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:param root_path: path to which files are read relative from. When the
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config object is created by the application, this is
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the application's :attr:`~flask.Flask.root_path`.
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:param defaults: an optional dictionary of default values
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"""
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def __init__(self, root_path: str, defaults: t.Optional[dict] = None) -> None:
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super().__init__(defaults or {})
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self.root_path = root_path
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def from_envvar(self, variable_name: str, silent: bool = False) -> bool:
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"""Loads a configuration from an environment variable pointing to
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a configuration file. This is basically just a shortcut with nicer
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error messages for this line of code::
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app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])
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:param variable_name: name of the environment variable
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:param silent: set to ``True`` if you want silent failure for missing
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files.
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:return: ``True`` if the file was loaded successfully.
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"""
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rv = os.environ.get(variable_name)
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if not rv:
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if silent:
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return False
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raise RuntimeError(
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f"The environment variable {variable_name!r} is not set"
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" and as such configuration could not be loaded. Set"
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" this variable and make it point to a configuration"
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" file"
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)
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return self.from_pyfile(rv, silent=silent)
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def from_prefixed_env(
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self, prefix: str = "FLASK", *, loads: t.Callable[[str], t.Any] = json.loads
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) -> bool:
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"""Load any environment variables that start with ``FLASK_``,
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dropping the prefix from the env key for the config key. Values
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are passed through a loading function to attempt to convert them
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to more specific types than strings.
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Keys are loaded in :func:`sorted` order.
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The default loading function attempts to parse values as any
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valid JSON type, including dicts and lists.
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Specific items in nested dicts can be set by separating the
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keys with double underscores (``__``). If an intermediate key
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doesn't exist, it will be initialized to an empty dict.
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:param prefix: Load env vars that start with this prefix,
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separated with an underscore (``_``).
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:param loads: Pass each string value to this function and use
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the returned value as the config value. If any error is
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raised it is ignored and the value remains a string. The
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default is :func:`json.loads`.
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.. versionadded:: 2.1
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"""
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prefix = f"{prefix}_"
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len_prefix = len(prefix)
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for key in sorted(os.environ):
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if not key.startswith(prefix):
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continue
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value = os.environ[key]
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try:
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value = loads(value)
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except Exception:
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# Keep the value as a string if loading failed.
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pass
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# Change to key.removeprefix(prefix) on Python >= 3.9.
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key = key[len_prefix:]
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if "__" not in key:
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# A non-nested key, set directly.
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self[key] = value
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continue
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# Traverse nested dictionaries with keys separated by "__".
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current = self
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*parts, tail = key.split("__")
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for part in parts:
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# If an intermediate dict does not exist, create it.
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if part not in current:
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current[part] = {}
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current = current[part]
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current[tail] = value
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return True
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def from_pyfile(self, filename: str, silent: bool = False) -> bool:
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"""Updates the values in the config from a Python file. This function
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behaves as if the file was imported as module with the
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:meth:`from_object` function.
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:param filename: the filename of the config. This can either be an
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absolute filename or a filename relative to the
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root path.
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:param silent: set to ``True`` if you want silent failure for missing
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files.
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:return: ``True`` if the file was loaded successfully.
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.. versionadded:: 0.7
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`silent` parameter.
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"""
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filename = os.path.join(self.root_path, filename)
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d = types.ModuleType("config")
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d.__file__ = filename
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try:
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with open(filename, mode="rb") as config_file:
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exec(compile(config_file.read(), filename, "exec"), d.__dict__)
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except OSError as e:
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if silent and e.errno in (errno.ENOENT, errno.EISDIR, errno.ENOTDIR):
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return False
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e.strerror = f"Unable to load configuration file ({e.strerror})"
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raise
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self.from_object(d)
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return True
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def from_object(self, obj: t.Union[object, str]) -> None:
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"""Updates the values from the given object. An object can be of one
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of the following two types:
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- a string: in this case the object with that name will be imported
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- an actual object reference: that object is used directly
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Objects are usually either modules or classes. :meth:`from_object`
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loads only the uppercase attributes of the module/class. A ``dict``
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object will not work with :meth:`from_object` because the keys of a
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``dict`` are not attributes of the ``dict`` class.
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Example of module-based configuration::
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app.config.from_object('yourapplication.default_config')
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from yourapplication import default_config
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app.config.from_object(default_config)
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Nothing is done to the object before loading. If the object is a
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class and has ``@property`` attributes, it needs to be
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instantiated before being passed to this method.
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You should not use this function to load the actual configuration but
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rather configuration defaults. The actual config should be loaded
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with :meth:`from_pyfile` and ideally from a location not within the
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package because the package might be installed system wide.
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See :ref:`config-dev-prod` for an example of class-based configuration
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using :meth:`from_object`.
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:param obj: an import name or object
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"""
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if isinstance(obj, str):
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obj = import_string(obj)
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for key in dir(obj):
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if key.isupper():
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self[key] = getattr(obj, key)
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def from_file(
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self,
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filename: str,
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load: t.Callable[[t.IO[t.Any]], t.Mapping],
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silent: bool = False,
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) -> bool:
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"""Update the values in the config from a file that is loaded
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using the ``load`` parameter. The loaded data is passed to the
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:meth:`from_mapping` method.
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.. code-block:: python
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import json
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app.config.from_file("config.json", load=json.load)
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import toml
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app.config.from_file("config.toml", load=toml.load)
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:param filename: The path to the data file. This can be an
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absolute path or relative to the config root path.
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:param load: A callable that takes a file handle and returns a
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mapping of loaded data from the file.
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:type load: ``Callable[[Reader], Mapping]`` where ``Reader``
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implements a ``read`` method.
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:param silent: Ignore the file if it doesn't exist.
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:return: ``True`` if the file was loaded successfully.
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.. versionadded:: 2.0
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"""
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filename = os.path.join(self.root_path, filename)
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try:
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with open(filename) as f:
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obj = load(f)
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except OSError as e:
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if silent and e.errno in (errno.ENOENT, errno.EISDIR):
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return False
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e.strerror = f"Unable to load configuration file ({e.strerror})"
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raise
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return self.from_mapping(obj)
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def from_mapping(
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self, mapping: t.Optional[t.Mapping[str, t.Any]] = None, **kwargs: t.Any
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) -> bool:
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"""Updates the config like :meth:`update` ignoring items with non-upper
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keys.
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:return: Always returns ``True``.
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.. versionadded:: 0.11
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"""
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mappings: t.Dict[str, t.Any] = {}
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if mapping is not None:
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mappings.update(mapping)
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mappings.update(kwargs)
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for key, value in mappings.items():
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if key.isupper():
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self[key] = value
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return True
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def get_namespace(
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self, namespace: str, lowercase: bool = True, trim_namespace: bool = True
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) -> t.Dict[str, t.Any]:
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"""Returns a dictionary containing a subset of configuration options
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that match the specified namespace/prefix. Example usage::
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app.config['IMAGE_STORE_TYPE'] = 'fs'
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app.config['IMAGE_STORE_PATH'] = '/var/app/images'
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app.config['IMAGE_STORE_BASE_URL'] = 'http://img.website.com'
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image_store_config = app.config.get_namespace('IMAGE_STORE_')
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The resulting dictionary `image_store_config` would look like::
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{
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'type': 'fs',
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'path': '/var/app/images',
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'base_url': 'http://img.website.com'
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}
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This is often useful when configuration options map directly to
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keyword arguments in functions or class constructors.
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:param namespace: a configuration namespace
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:param lowercase: a flag indicating if the keys of the resulting
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dictionary should be lowercase
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:param trim_namespace: a flag indicating if the keys of the resulting
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dictionary should not include the namespace
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.. versionadded:: 0.11
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"""
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rv = {}
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for k, v in self.items():
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if not k.startswith(namespace):
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continue
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if trim_namespace:
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key = k[len(namespace) :]
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else:
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key = k
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if lowercase:
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key = key.lower()
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rv[key] = v
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return rv
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def __repr__(self) -> str:
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return f"<{type(self).__name__} {dict.__repr__(self)}>"
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