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