# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the MIT License. See the LICENSE file in the root of this
# repository for complete details.
"""
Processors and helpers specific to the :mod:`logging` module from the `Python
standard library <https://docs.python.org/>`_.
See also :doc:`structlog's standard library support <standard-library>`.
"""
from __future__ import absolute_import, division, print_function
import logging
from six import PY3
from structlog._base import BoundLoggerBase
from structlog._frames import _find_first_app_frame_and_name, _format_stack
from structlog.exceptions import DropEvent
class _FixedFindCallerLogger(logging.Logger):
"""
Change the behavior of findCaller to cope with structlog's extra frames.
"""
def findCaller(self, stack_info=False):
"""
Finds the first caller frame outside of structlog so that the caller
info is populated for wrapping stdlib.
This logger gets set as the default one when using LoggerFactory.
"""
f, name = _find_first_app_frame_and_name(["logging"])
if PY3:
if stack_info:
sinfo = _format_stack(f)
else:
sinfo = None
return f.f_code.co_filename, f.f_lineno, f.f_code.co_name, sinfo
else:
return f.f_code.co_filename, f.f_lineno, f.f_code.co_name
[docs]class BoundLogger(BoundLoggerBase):
"""
Python Standard Library version of :class:`structlog.BoundLogger`.
Works exactly like the generic one except that it takes advantage of
knowing the logging methods in advance.
Use it like::
structlog.configure(
wrapper_class=structlog.stdlib.BoundLogger,
)
"""
[docs] def debug(self, event=None, *args, **kw):
"""
Process event and call :meth:`logging.Logger.debug` with the result.
"""
return self._proxy_to_logger("debug", event, *args, **kw)
[docs] def info(self, event=None, *args, **kw):
"""
Process event and call :meth:`logging.Logger.info` with the result.
"""
return self._proxy_to_logger("info", event, *args, **kw)
[docs] def warning(self, event=None, *args, **kw):
"""
Process event and call :meth:`logging.Logger.warning` with the result.
"""
return self._proxy_to_logger("warning", event, *args, **kw)
warn = warning
[docs] def error(self, event=None, *args, **kw):
"""
Process event and call :meth:`logging.Logger.error` with the result.
"""
return self._proxy_to_logger("error", event, *args, **kw)
[docs] def critical(self, event=None, *args, **kw):
"""
Process event and call :meth:`logging.Logger.critical` with the result.
"""
return self._proxy_to_logger("critical", event, *args, **kw)
[docs] def exception(self, event=None, *args, **kw):
"""
Process event and call :meth:`logging.Logger.error` with the result,
after setting ``exc_info`` to `True`.
"""
kw.setdefault("exc_info", True)
return self.error(event, *args, **kw)
[docs] def log(self, level, event, *args, **kw):
"""
Process event and call the appropriate logging method depending on
`level`.
"""
return self._proxy_to_logger(_LEVEL_TO_NAME[level], event, *args, **kw)
fatal = critical
def _proxy_to_logger(self, method_name, event, *event_args, **event_kw):
"""
Propagate a method call to the wrapped logger.
This is the same as the superclass implementation, except that
it also preserves positional arguments in the `event_dict` so
that the stdblib's support for format strings can be used.
"""
if event_args:
event_kw["positional_args"] = event_args
return super(BoundLogger, self)._proxy_to_logger(
method_name, event=event, **event_kw
)
#
# Pass-through methods to mimick the stdlib's logger interface.
#
def setLevel(self, level):
"""
Calls :meth:`logging.Logger.setLevel` with unmodified arguments.
"""
self._logger.setLevel(level)
def findCaller(self, stack_info=False):
"""
Calls :meth:`logging.Logger.findCaller` with unmodified arguments.
"""
return self._logger.findCaller(stack_info=stack_info)
def makeRecord(
self, name, level, fn, lno, msg, args, exc_info, func=None, extra=None
):
"""
Calls :meth:`logging.Logger.makeRecord` with unmodified arguments.
"""
return self._logger.makeRecord(
name, level, fn, lno, msg, args, exc_info, func=func, extra=extra
)
def handle(self, record):
"""
Calls :meth:`logging.Logger.handle` with unmodified arguments.
"""
self._logger.handle(record)
def addHandler(self, hdlr):
"""
Calls :meth:`logging.Logger.addHandler` with unmodified arguments.
"""
self._logger.addHandler(hdlr)
def removeHandler(self, hdlr):
"""
Calls :meth:`logging.Logger.removeHandler` with unmodified arguments.
"""
self._logger.removeHandler(hdlr)
def hasHandlers(self):
"""
Calls :meth:`logging.Logger.hasHandlers` with unmodified arguments.
Exists only in Python 3.
"""
return self._logger.hasHandlers()
def callHandlers(self, record):
"""
Calls :meth:`logging.Logger.callHandlers` with unmodified arguments.
"""
self._logger.callHandlers(record)
def getEffectiveLevel(self):
"""
Calls :meth:`logging.Logger.getEffectiveLevel` with unmodified
arguments.
"""
return self._logger.getEffectiveLevel()
def isEnabledFor(self, level):
"""
Calls :meth:`logging.Logger.isEnabledFor` with unmodified arguments.
"""
return self._logger.isEnabledFor(level)
def getChild(self, suffix):
"""
Calls :meth:`logging.Logger.getChild` with unmodified arguments.
"""
return self._logger.getChild(suffix)
[docs]class LoggerFactory(object):
"""
Build a standard library logger when an *instance* is called.
Sets a custom logger using :func:`logging.setLoggerClass` so variables in
log format are expanded properly.
>>> from structlog import configure
>>> from structlog.stdlib import LoggerFactory
>>> configure(logger_factory=LoggerFactory())
:param ignore_frame_names: When guessing the name of a logger, skip frames
whose names *start* with one of these. For example, in pyramid
applications you'll want to set it to
``["venusian", "pyramid.config"]``.
:type ignore_frame_names: ``list`` of ``str``
"""
def __init__(self, ignore_frame_names=None):
self._ignore = ignore_frame_names
logging.setLoggerClass(_FixedFindCallerLogger)
[docs] def __call__(self, *args):
"""
Deduce the caller's module name and create a stdlib logger.
If an optional argument is passed, it will be used as the logger name
instead of guesswork. This optional argument would be passed from the
:func:`structlog.get_logger` call. For example
``structlog.get_logger("foo")`` would cause this method to be called
with ``"foo"`` as its first positional argument.
:rtype: logging.Logger
.. versionchanged:: 0.4.0
Added support for optional positional arguments. Using the first
one for naming the constructed logger.
"""
if args:
return logging.getLogger(args[0])
# We skip all frames that originate from within structlog or one of the
# configured names.
_, name = _find_first_app_frame_and_name(self._ignore)
return logging.getLogger(name)
# Adapted from the stdlib
CRITICAL = 50
FATAL = CRITICAL
ERROR = 40
WARNING = 30
WARN = WARNING
INFO = 20
DEBUG = 10
NOTSET = 0
_NAME_TO_LEVEL = {
"critical": CRITICAL,
"exception": ERROR,
"error": ERROR,
"warn": WARNING,
"warning": WARNING,
"info": INFO,
"debug": DEBUG,
"notset": NOTSET,
}
_LEVEL_TO_NAME = dict(
(v, k)
for k, v in _NAME_TO_LEVEL.items()
if k not in ("warn", "exception", "notset")
)
[docs]def filter_by_level(logger, name, event_dict):
"""
Check whether logging is configured to accept messages from this log level.
Should be the first processor if stdlib's filtering by level is used so
possibly expensive processors like exception formatters are avoided in the
first place.
>>> import logging
>>> from structlog.stdlib import filter_by_level
>>> logging.basicConfig(level=logging.WARN)
>>> logger = logging.getLogger()
>>> filter_by_level(logger, 'warn', {})
{}
>>> filter_by_level(logger, 'debug', {})
Traceback (most recent call last):
...
DropEvent
"""
if logger.isEnabledFor(_NAME_TO_LEVEL[name]):
return event_dict
else:
raise DropEvent
[docs]def add_log_level(logger, method_name, event_dict):
"""
Add the log level to the event dict.
"""
if method_name == "warn":
# The stdlib has an alias
method_name = "warning"
event_dict["level"] = method_name
return event_dict
[docs]def add_log_level_number(logger, method_name, event_dict):
"""
Add the log level number to the event dict.
Log level numbers map to the log level names. The Python stdlib uses them
for filtering logic. This adds the same numbers so users can leverage
similar filtering. Compare::
level in ("warning", "error", "critical")
level_number >= 30
The mapping of names to numbers is in
:data:`~structlog.stdlib._NAME_TO_LEVEL`.
.. versionadded:: 18.2.0
"""
event_dict["level_number"] = _NAME_TO_LEVEL[method_name]
return event_dict
[docs]def add_logger_name(logger, method_name, event_dict):
"""
Add the logger name to the event dict.
"""
record = event_dict.get("_record")
if record is None:
event_dict["logger"] = logger.name
else:
event_dict["logger"] = record.name
return event_dict
[docs]def render_to_log_kwargs(wrapped_logger, method_name, event_dict):
"""
Render `event_dict` into keyword arguments for :func:`logging.log`.
The `event` field is translated into `msg` and the rest of the `event_dict`
is added as `extra`.
This allows you to defer formatting to :mod:`logging`.
.. versionadded:: 17.1.0
"""
return {"msg": event_dict.pop("event"), "extra": event_dict}