import logging import sys import typing as t from werkzeug.local import LocalProxy from .globals import request if t.TYPE_CHECKING: from .app import Flask @LocalProxy def wsgi_errors_stream() -> t.TextIO: """Find the most appropriate error stream for the application. If a request is active, log to ``wsgi.errors``, otherwise use ``sys.stderr``. If you configure your own :class:`logging.StreamHandler`, you may want to use this for the stream. If you are using file or dict configuration and can't import this directly, you can refer to it as ``ext://flask.logging.wsgi_errors_stream``. """ return request.environ["wsgi.errors"] if request else sys.stderr def has_level_handler(logger: logging.Logger) -> bool: """Check if there is a handler in the logging chain that will handle the given logger's :meth:`effective level <~logging.Logger.getEffectiveLevel>`. """ level = logger.getEffectiveLevel() current = logger while current: if any(handler.level <= level for handler in current.handlers): return True if not current.propagate: break current = current.parent # type: ignore return False #: Log messages to :func:`~flask.logging.wsgi_errors_stream` with the format #: ``[%(asctime)s] %(levelname)s in %(module)s: %(message)s``. default_handler = logging.StreamHandler(wsgi_errors_stream) # type: ignore default_handler.setFormatter( logging.Formatter("[%(asctime)s] %(levelname)s in %(module)s: %(message)s") ) def create_logger(app: "Flask") -> logging.Logger: """Get the Flask app's logger and configure it if needed. The logger name will be the same as :attr:`app.import_name `. When :attr:`~flask.Flask.debug` is enabled, set the logger level to :data:`logging.DEBUG` if it is not set. If there is no handler for the logger's effective level, add a :class:`~logging.StreamHandler` for :func:`~flask.logging.wsgi_errors_stream` with a basic format. """ logger = logging.getLogger(app.name) if app.debug and not logger.level: logger.setLevel(logging.DEBUG) if not has_level_handler(logger): logger.addHandler(default_handler) return logger