# 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 `_.
See also :doc:`structlog's standard library support `.
"""
from __future__ import annotations
import asyncio
import contextvars
import functools
import logging
import sys
from functools import partial
from typing import Any, Callable, Collection, Iterable, Sequence
from . import _config
from ._base import BoundLoggerBase
from ._frames import _find_first_app_frame_and_name, _format_stack
from ._log_levels import _LEVEL_TO_NAME, _NAME_TO_LEVEL, add_log_level
from .contextvars import merge_contextvars
from .exceptions import DropEvent
from .processors import StackInfoRenderer
from .typing import Context, EventDict, ExcInfo, Processor, WrappedLogger
__all__ = [
"add_log_level_number",
"add_log_level",
"add_logger_name",
"ExtraAdder",
"BoundLogger",
"filter_by_level",
"get_logger",
"LoggerFactory",
"PositionalArgumentsFormatter",
"ProcessorFormatter",
"recreate_defaults",
"render_to_log_kwargs",
]
def recreate_defaults(*, log_level: int | None = logging.NOTSET) -> None:
"""
Recreate defaults on top of standard library's logging.
The output looks the same, but goes through `logging`.
As with vanilla defaults, the backwards-compatibility guarantees don't
apply to the settings applied here.
Arguments:
log_level:
If `None`, don't configure standard library logging **at all**.
Otherwise configure it to log to `sys.stdout` at *log_level*
(``logging.NOTSET`` being the default).
If you need more control over `logging`, pass `None` here and
configure it yourself.
.. versionadded:: 22.1.0
"""
if log_level is not None:
kw = {"force": True}
logging.basicConfig(
format="%(message)s",
stream=sys.stdout,
level=log_level,
**kw, # type: ignore[arg-type]
)
_config.reset_defaults()
_config.configure(
processors=[
merge_contextvars,
add_log_level,
StackInfoRenderer(),
_config._BUILTIN_DEFAULT_PROCESSORS[-2], # TimeStamper
_config._BUILTIN_DEFAULT_PROCESSORS[-1], # ConsoleRenderer
],
wrapper_class=BoundLogger,
logger_factory=LoggerFactory(),
)
_SENTINEL = object()
class _FixedFindCallerLogger(logging.Logger):
"""
Change the behavior of `logging.Logger.findCaller` to cope with
*structlog*'s extra frames.
"""
def findCaller(
self, stack_info: bool = False, stacklevel: int = 1
) -> tuple[str, int, str, str | None]:
"""
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.
"""
sinfo: str | None
f, name = _find_first_app_frame_and_name(["logging"])
sinfo = _format_stack(f) if stack_info else None
return f.f_code.co_filename, f.f_lineno, f.f_code.co_name, sinfo
class BoundLogger(BoundLoggerBase):
"""
Python Standard Library version of `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,
)
It also contains a bunch of properties that pass-through to the wrapped
`logging.Logger` which should make it work as a drop-in replacement.
.. versionadded:: 23.1.0
Async variants `alog()`, `adebug()`, `ainfo()`, and so forth.
"""
_logger: logging.Logger
def bind(self, **new_values: Any) -> BoundLogger:
"""
Return a new logger with *new_values* added to the existing ones.
"""
return super().bind(**new_values) # type: ignore[return-value]
def unbind(self, *keys: str) -> BoundLogger:
"""
Return a new logger with *keys* removed from the context.
Raises:
KeyError: If the key is not part of the context.
"""
return super().unbind(*keys) # type: ignore[return-value]
def try_unbind(self, *keys: str) -> BoundLogger:
"""
Like :meth:`unbind`, but best effort: missing keys are ignored.
.. versionadded:: 18.2.0
"""
return super().try_unbind(*keys) # type: ignore[return-value]
def new(self, **new_values: Any) -> BoundLogger:
"""
Clear context and binds *initial_values* using `bind`.
Only necessary with dict implementations that keep global state like
those wrapped by `structlog.threadlocal.wrap_dict` when threads
are re-used.
"""
return super().new(**new_values) # type: ignore[return-value]
def debug(self, event: str | None = None, *args: Any, **kw: Any) -> Any:
"""
Process event and call `logging.Logger.debug` with the result.
"""
return self._proxy_to_logger("debug", event, *args, **kw)
def info(self, event: str | None = None, *args: Any, **kw: Any) -> Any:
"""
Process event and call `logging.Logger.info` with the result.
"""
return self._proxy_to_logger("info", event, *args, **kw)
def warning(self, event: str | None = None, *args: Any, **kw: Any) -> Any:
"""
Process event and call `logging.Logger.warning` with the result.
"""
return self._proxy_to_logger("warning", event, *args, **kw)
warn = warning
def error(self, event: str | None = None, *args: Any, **kw: Any) -> Any:
"""
Process event and call `logging.Logger.error` with the result.
"""
return self._proxy_to_logger("error", event, *args, **kw)
def critical(self, event: str | None = None, *args: Any, **kw: Any) -> Any:
"""
Process event and call `logging.Logger.critical` with the result.
"""
return self._proxy_to_logger("critical", event, *args, **kw)
def exception(
self, event: str | None = None, *args: Any, **kw: Any
) -> Any:
"""
Process event and call `logging.Logger.error` with the result,
after setting ``exc_info`` to `True`.
"""
kw.setdefault("exc_info", True)
return self.error(event, *args, **kw)
def log(
self, level: int, event: str | None = None, *args: Any, **kw: Any
) -> Any:
"""
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: str,
event: str | None = None,
*event_args: str,
**event_kw: Any,
) -> Any:
"""
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 stdlib's support for format strings can be used.
"""
if event_args:
event_kw["positional_args"] = event_args
return super()._proxy_to_logger(method_name, event=event, **event_kw)
# Pass-through attributes and methods to mimic the stdlib's logger
# interface.
@property
def name(self) -> str:
"""
Returns :attr:`logging.Logger.name`
"""
return self._logger.name
@property
def level(self) -> int:
"""
Returns :attr:`logging.Logger.level`
"""
return self._logger.level
@property
def parent(self) -> Any:
"""
Returns :attr:`logging.Logger.parent`
"""
return self._logger.parent
@property
def propagate(self) -> bool:
"""
Returns :attr:`logging.Logger.propagate`
"""
return self._logger.propagate
@property
def handlers(self) -> Any:
"""
Returns :attr:`logging.Logger.handlers`
"""
return self._logger.handlers
@property
def disabled(self) -> int:
"""
Returns :attr:`logging.Logger.disabled`
"""
return self._logger.disabled
def setLevel(self, level: int) -> None:
"""
Calls :meth:`logging.Logger.setLevel` with unmodified arguments.
"""
self._logger.setLevel(level)
def findCaller(
self, stack_info: bool = False
) -> tuple[str, int, str, str | None]:
"""
Calls :meth:`logging.Logger.findCaller` with unmodified arguments.
"""
return self._logger.findCaller(stack_info=stack_info)
def makeRecord(
self,
name: str,
level: int,
fn: str,
lno: int,
msg: str,
args: tuple[Any, ...],
exc_info: ExcInfo,
func: str | None = None,
extra: Any = None,
) -> logging.LogRecord:
"""
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: logging.LogRecord) -> None:
"""
Calls :meth:`logging.Logger.handle` with unmodified arguments.
"""
self._logger.handle(record)
def addHandler(self, hdlr: logging.Handler) -> None:
"""
Calls :meth:`logging.Logger.addHandler` with unmodified arguments.
"""
self._logger.addHandler(hdlr)
def removeHandler(self, hdlr: logging.Handler) -> None:
"""
Calls :meth:`logging.Logger.removeHandler` with unmodified arguments.
"""
self._logger.removeHandler(hdlr)
def hasHandlers(self) -> bool:
"""
Calls :meth:`logging.Logger.hasHandlers` with unmodified arguments.
Exists only in Python 3.
"""
return self._logger.hasHandlers()
def callHandlers(self, record: logging.LogRecord) -> None:
"""
Calls :meth:`logging.Logger.callHandlers` with unmodified arguments.
"""
self._logger.callHandlers(record)
def getEffectiveLevel(self) -> int:
"""
Calls :meth:`logging.Logger.getEffectiveLevel` with unmodified
arguments.
"""
return self._logger.getEffectiveLevel()
def isEnabledFor(self, level: int) -> bool:
"""
Calls :meth:`logging.Logger.isEnabledFor` with unmodified arguments.
"""
return self._logger.isEnabledFor(level)
def getChild(self, suffix: str) -> logging.Logger:
"""
Calls :meth:`logging.Logger.getChild` with unmodified arguments.
"""
return self._logger.getChild(suffix)
# Non-Standard Async
async def _dispatch_to_sync(
self,
meth: Callable[..., Any],
event: str,
args: tuple[Any, ...],
kw: dict[str, Any],
) -> None:
"""
Merge contextvars and log using the sync logger in a thread pool.
"""
ctx = contextvars.copy_context()
await asyncio.get_running_loop().run_in_executor(
None,
lambda: ctx.run(lambda: meth(event, *args, **kw)),
)
async def adebug(self, event: str, *args: Any, **kw: Any) -> None:
"""
Log using `debug()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
await self._dispatch_to_sync(self.debug, event, args, kw)
async def ainfo(self, event: str, *args: Any, **kw: Any) -> None:
"""
Log using `info()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
await self._dispatch_to_sync(self.info, event, args, kw)
async def awarning(self, event: str, *args: Any, **kw: Any) -> None:
"""
Log using `warning()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
await self._dispatch_to_sync(self.warning, event, args, kw)
async def aerror(self, event: str, *args: Any, **kw: Any) -> None:
"""
Log using `error()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
await self._dispatch_to_sync(self.error, event, args, kw)
async def acritical(self, event: str, *args: Any, **kw: Any) -> None:
"""
Log using `critical()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
await self._dispatch_to_sync(self.critical, event, args, kw)
afatal = acritical
async def aexception(self, event: str, *args: Any, **kw: Any) -> None:
"""
Log using `exception()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
# To make `log.exception("foo") work, we have to check if the user
# passed an explicit exc_info and if not, supply our own.
if kw.get("exc_info", True) is True and kw.get("exception") is None:
kw["exc_info"] = sys.exc_info()
await self._dispatch_to_sync(self.exception, event, args, kw)
async def alog(
self, level: Any, event: str, *args: Any, **kw: Any
) -> None:
"""
Log using `log()`, but asynchronously in a separate thread.
.. versionadded:: 23.1.0
"""
await self._dispatch_to_sync(partial(self.log, level), event, args, kw)
def get_logger(*args: Any, **initial_values: Any) -> BoundLogger:
"""
Only calls `structlog.get_logger`, but has the correct type hints.
.. warning::
Does **not** check whether -- or ensure that -- you've configured
*structlog* for standard library :mod:`logging`!
See :doc:`standard-library` for details.
.. versionadded:: 20.2.0
"""
return _config.get_logger(*args, **initial_values)
class AsyncBoundLogger:
"""
Wraps a `BoundLogger` & exposes its logging methods as ``async`` versions.
Instead of blocking the program, they are run asynchronously in a thread
pool executor.
This means more computational overhead per log call. But it also means that
the processor chain (e.g. JSON serialization) and I/O won't block your
whole application.
Only available for Python 3.7 and later.
.. versionadded:: 20.2.0
.. versionchanged:: 20.2.0 fix _dispatch_to_sync contextvars usage
.. deprecated:: 23.1.0
Use the regular `BoundLogger` with its a-prefixed methods instead.
"""
__slots__ = ("sync_bl", "_loop")
#: The wrapped synchronous logger. It is useful to be able to log
#: synchronously occasionally.
sync_bl: BoundLogger
# Blatant lie, we use a property for _context. Need this for Protocol
# though.
_context: Context
_executor = None
_bound_logger_factory = BoundLogger
def __init__(
self,
logger: logging.Logger,
processors: Iterable[Processor],
context: Context,
*,
# Only as an optimization for binding!
_sync_bl: Any = None, # *vroom vroom* over purity.
_loop: Any = None,
):
if _sync_bl:
self.sync_bl = _sync_bl
self._loop = _loop
return
self.sync_bl = self._bound_logger_factory(
logger=logger, processors=processors, context=context
)
self._loop = asyncio.get_running_loop()
# We have to ignore the type because we've already declared it to ensure
# we're a BindableLogger.
# Instances would've been correctly recognized as such, however the class
# not and we need the class in `structlog.configure()`.
@property # type: ignore[no-redef]
def _context(self) -> Context:
return self.sync_bl._context
def bind(self, **new_values: Any) -> AsyncBoundLogger:
return AsyncBoundLogger(
# logger, processors and context are within sync_bl. These
# arguments are ignored if _sync_bl is passed. *vroom vroom* over
# purity.
logger=None, # type: ignore[arg-type]
processors=(),
context={},
_sync_bl=self.sync_bl.bind(**new_values),
_loop=self._loop,
)
def new(self, **new_values: Any) -> AsyncBoundLogger:
return AsyncBoundLogger(
# c.f. comment in bind
logger=None, # type: ignore[arg-type]
processors=(),
context={},
_sync_bl=self.sync_bl.new(**new_values),
_loop=self._loop,
)
def unbind(self, *keys: str) -> AsyncBoundLogger:
return AsyncBoundLogger(
# c.f. comment in bind
logger=None, # type: ignore[arg-type]
processors=(),
context={},
_sync_bl=self.sync_bl.unbind(*keys),
_loop=self._loop,
)
def try_unbind(self, *keys: str) -> AsyncBoundLogger:
return AsyncBoundLogger(
# c.f. comment in bind
logger=None, # type: ignore[arg-type]
processors=(),
context={},
_sync_bl=self.sync_bl.try_unbind(*keys),
_loop=self._loop,
)
async def _dispatch_to_sync(
self,
meth: Callable[..., Any],
event: str,
args: tuple[Any, ...],
kw: dict[str, Any],
) -> None:
"""
Merge contextvars and log using the sync logger in a thread pool.
"""
ctx = contextvars.copy_context()
await asyncio.get_running_loop().run_in_executor(
self._executor,
lambda: ctx.run(lambda: meth(event, *args, **kw)),
)
async def debug(self, event: str, *args: Any, **kw: Any) -> None:
await self._dispatch_to_sync(self.sync_bl.debug, event, args, kw)
async def info(self, event: str, *args: Any, **kw: Any) -> None:
await self._dispatch_to_sync(self.sync_bl.info, event, args, kw)
async def warning(self, event: str, *args: Any, **kw: Any) -> None:
await self._dispatch_to_sync(self.sync_bl.warning, event, args, kw)
warn = warning
async def error(self, event: str, *args: Any, **kw: Any) -> None:
await self._dispatch_to_sync(self.sync_bl.error, event, args, kw)
async def critical(self, event: str, *args: Any, **kw: Any) -> None:
await self._dispatch_to_sync(self.sync_bl.critical, event, args, kw)
fatal = critical
async def exception(self, event: str, *args: Any, **kw: Any) -> None:
# To make `log.exception("foo") work, we have to check if the user
# passed an explicit exc_info and if not, supply our own.
ei = kw.pop("exc_info", None)
if ei is None and kw.get("exception") is None:
ei = sys.exc_info()
kw["exc_info"] = ei
await self._dispatch_to_sync(self.sync_bl.exception, event, args, kw)
async def log(self, level: Any, event: str, *args: Any, **kw: Any) -> None:
await self._dispatch_to_sync(
partial(self.sync_bl.log, level), event, args, kw
)
class LoggerFactory:
"""
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())
Arguments:
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"]``. This argument
is called *additional_ignores* in other APIs throughout
*structlog*.
"""
def __init__(self, ignore_frame_names: list[str] | None = None):
self._ignore = ignore_frame_names
logging.setLoggerClass(_FixedFindCallerLogger)
def __call__(self, *args: Any) -> logging.Logger:
"""
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.
.. 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)
class PositionalArgumentsFormatter:
"""
Apply stdlib-like string formatting to the ``event`` key.
If the ``positional_args`` key in the event dict is set, it must
contain a tuple that is used for formatting (using the ``%s`` string
formatting operator) of the value from the ``event`` key. This works
in the same way as the stdlib handles arguments to the various log
methods: if the tuple contains only a single `dict` argument it is
used for keyword placeholders in the ``event`` string, otherwise it
will be used for positional placeholders.
``positional_args`` is populated by `structlog.stdlib.BoundLogger` or
can be set manually.
The *remove_positional_args* flag can be set to `False` to keep the
``positional_args`` key in the event dict; by default it will be
removed from the event dict after formatting a message.
"""
def __init__(self, remove_positional_args: bool = True) -> None:
self.remove_positional_args = remove_positional_args
def __call__(
self, _: WrappedLogger, __: str, event_dict: EventDict
) -> EventDict:
args = event_dict.get("positional_args")
# Mimic the formatting behaviour of the stdlib's logging module, which
# accepts both positional arguments and a single dict argument. The
# "single dict" check is the same one as the stdlib's logging module
# performs in LogRecord.__init__().
if args:
if len(args) == 1 and isinstance(args[0], dict) and args[0]:
args = args[0]
event_dict["event"] %= args
if self.remove_positional_args and args is not None:
del event_dict["positional_args"]
return event_dict
def filter_by_level(
logger: logging.Logger, method_name: str, event_dict: EventDict
) -> EventDict:
"""
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[method_name]):
return event_dict
raise DropEvent
def add_log_level_number(
logger: logging.Logger, method_name: str, event_dict: EventDict
) -> EventDict:
"""
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
``structlog.stdlib._log_levels._NAME_TO_LEVEL``.
.. versionadded:: 18.2.0
"""
event_dict["level_number"] = _NAME_TO_LEVEL[method_name]
return event_dict
def add_logger_name(
logger: logging.Logger, method_name: str, event_dict: EventDict
) -> EventDict:
"""
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
_LOG_RECORD_KEYS = logging.LogRecord(
"name", 0, "pathname", 0, "msg", (), None
).__dict__.keys()
class ExtraAdder:
"""
Add extra attributes of `logging.LogRecord` objects to the event
dictionary.
This processor can be used for adding data passed in the ``extra``
parameter of the `logging` module's log methods to the event dictionary.
Arguments:
allow:
An optional collection of attributes that, if present in
`logging.LogRecord` objects, will be copied to event dictionaries.
If ``allow`` is None all attributes of `logging.LogRecord` objects
that do not exist on a standard `logging.LogRecord` object will be
copied to event dictionaries.
.. versionadded:: 21.5.0
"""
__slots__ = ("_copier",)
def __init__(self, allow: Collection[str] | None = None) -> None:
self._copier: Callable[[EventDict, logging.LogRecord], None]
if allow is not None:
# The contents of allow is copied to a new list so that changes to
# the list passed into the constructor does not change the
# behaviour of this processor.
self._copier = functools.partial(self._copy_allowed, [*allow])
else:
self._copier = self._copy_all
def __call__(
self, logger: logging.Logger, name: str, event_dict: EventDict
) -> EventDict:
record: logging.LogRecord | None = event_dict.get("_record")
if record is not None:
self._copier(event_dict, record)
return event_dict
@classmethod
def _copy_all(
cls, event_dict: EventDict, record: logging.LogRecord
) -> None:
for key, value in record.__dict__.items():
if key not in _LOG_RECORD_KEYS:
event_dict[key] = value
@classmethod
def _copy_allowed(
cls,
allow: Collection[str],
event_dict: EventDict,
record: logging.LogRecord,
) -> None:
for key in allow:
if key in record.__dict__:
event_dict[key] = record.__dict__[key]
def render_to_log_kwargs(
_: logging.Logger, __: str, event_dict: EventDict
) -> EventDict:
"""
Render ``event_dict`` into keyword arguments for `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 `logging`.
.. versionadded:: 17.1.0
.. versionchanged:: 22.1.0
``exc_info``, ``stack_info``, and ``stackLevel`` are passed as proper
kwargs and not put into ``extra``.
"""
return {
"msg": event_dict.pop("event"),
"extra": event_dict,
**{
kw: event_dict.pop(kw)
for kw in ("exc_info", "stack_info", "stackLevel")
if kw in event_dict
},
}
class ProcessorFormatter(logging.Formatter):
r"""
Call *structlog* processors on `logging.LogRecord`\s.
This is an implementation of a `logging.Formatter` that can be used to
format log entries from both *structlog* and `logging`.
Its static method `wrap_for_formatter` must be the final processor in
*structlog*'s processor chain.
Please refer to :ref:`processor-formatter` for examples.
Arguments:
foreign_pre_chain:
If not `None`, it is used as a processor chain that is applied to
**non**-*structlog* log entries before the event dictionary is
passed to *processors*. (default: `None`)
processors:
A chain of *structlog* processors that is used to process **all**
log entries. The last one must render to a `str` which then gets
passed on to `logging` for output.
Compared to *structlog*'s regular processor chains, there's a few
differences:
- The event dictionary contains two additional keys:
#. ``_record``: a `logging.LogRecord` that either was created
using `logging` APIs, **or** is a wrapped *structlog* log
entry created by `wrap_for_formatter`.
#. ``_from_structlog``: a `bool` that indicates whether or not
``_record`` was created by a *structlog* logger.
Since you most likely don't want ``_record`` and
``_from_structlog`` in your log files, we've added the static
method `remove_processors_meta` to ``ProcessorFormatter`` that
you can add just before your renderer.
- Since this is a `logging` *formatter*, raising
`structlog.DropEvent` will crash your application.
keep_exc_info:
``exc_info`` on `logging.LogRecord`\ s is added to the
``event_dict`` and removed afterwards. Set this to ``True`` to keep
it on the `logging.LogRecord`. (default: False)
keep_stack_info:
Same as *keep_exc_info* except for ``stack_info``. (default: False)
logger:
Logger which we want to push through the *structlog* processor
chain. This parameter is necessary for some of the processors like
`filter_by_level`. (default: None)
pass_foreign_args:
If True, pass a foreign log record's ``args`` attribute to the
``event_dict`` under ``positional_args`` key. (default: False)
processor:
A single *structlog* processor used for rendering the event
dictionary before passing it off to `logging`. Must return a `str`.
The event dictionary does **not** contain ``_record`` and
``_from_structlog``.
This parameter exists for historic reasons. Please use *processors*
instead.
Raises:
TypeError: If both or neither *processor* and *processors* are passed.
.. versionadded:: 17.1.0
.. versionadded:: 17.2.0 *keep_exc_info* and *keep_stack_info*
.. versionadded:: 19.2.0 *logger*
.. versionadded:: 19.2.0 *pass_foreign_args*
.. versionadded:: 21.3.0 *processors*
.. deprecated:: 21.3.0
*processor* (singular) in favor of *processors* (plural). Removal is not
planned.
"""
def __init__(
self,
processor: Processor | None = None,
processors: Sequence[Processor] | None = (),
foreign_pre_chain: Sequence[Processor] | None = None,
keep_exc_info: bool = False,
keep_stack_info: bool = False,
logger: logging.Logger | None = None,
pass_foreign_args: bool = False,
*args: Any,
**kwargs: Any,
) -> None:
fmt = kwargs.pop("fmt", "%(message)s")
super().__init__(*args, fmt=fmt, **kwargs) # type: ignore[misc]
if processor and processors:
msg = "The `processor` and `processors` arguments are mutually exclusive."
raise TypeError(msg)
self.processors: Sequence[Processor]
if processor is not None:
self.processors = (self.remove_processors_meta, processor)
elif processors:
self.processors = processors
else:
msg = "Either `processor` or `processors` must be passed."
raise TypeError(msg)
self.foreign_pre_chain = foreign_pre_chain
self.keep_exc_info = keep_exc_info
self.keep_stack_info = keep_stack_info
self.logger = logger
self.pass_foreign_args = pass_foreign_args
def format(self, record: logging.LogRecord) -> str:
"""
Extract *structlog*'s `event_dict` from ``record.msg`` and format it.
*record* has been patched by `wrap_for_formatter` first though, so the
type isn't quite right.
"""
# Make a shallow copy of the record to let other handlers/formatters
# process the original one
record = logging.makeLogRecord(record.__dict__)
logger = getattr(record, "_logger", _SENTINEL)
meth_name = getattr(record, "_name", "__structlog_sentinel__")
if logger is not _SENTINEL and meth_name != "__structlog_sentinel__":
# Both attached by wrap_for_formatter
if self.logger is not None:
logger = self.logger
meth_name = record._name # type: ignore[attr-defined]
# We need to copy because it's possible that the same record gets
# processed by multiple logging formatters. LogRecord.getMessage
# would transform our dict into a str.
ed = record.msg.copy() # type: ignore[union-attr]
ed["_record"] = record
ed["_from_structlog"] = True
else:
logger = self.logger
meth_name = record.levelname.lower()
ed = {
"event": record.getMessage(),
"_record": record,
"_from_structlog": False,
}
if self.pass_foreign_args:
ed["positional_args"] = record.args
record.args = ()
# Add stack-related attributes to event_dict and unset them
# on the record copy so that the base implementation wouldn't
# append stacktraces to the output.
if record.exc_info:
ed["exc_info"] = record.exc_info
if record.stack_info:
ed["stack_info"] = record.stack_info
if not self.keep_exc_info:
record.exc_text = None
record.exc_info = None
if not self.keep_stack_info:
record.stack_info = None
# Non-structlog allows to run through a chain to prepare it for the
# final processor (e.g. adding timestamps and log levels).
for proc in self.foreign_pre_chain or ():
ed = proc(logger, meth_name, ed)
for p in self.processors:
ed = p(logger, meth_name, ed)
record.msg = ed
return super().format(record)
@staticmethod
def wrap_for_formatter(
logger: logging.Logger, name: str, event_dict: EventDict
) -> tuple[tuple[EventDict], dict[str, dict[str, Any]]]:
"""
Wrap *logger*, *name*, and *event_dict*.
The result is later unpacked by `ProcessorFormatter` when
formatting log entries.
Use this static method as the renderer (i.e. final processor) if you
want to use `ProcessorFormatter` in your `logging` configuration.
"""
return (event_dict,), {"extra": {"_logger": logger, "_name": name}}
@staticmethod
def remove_processors_meta(
_: WrappedLogger, __: str, event_dict: EventDict
) -> EventDict:
"""
Remove ``_record`` and ``_from_structlog`` from *event_dict*.
These keys are added to the event dictionary, before
`ProcessorFormatter`'s *processors* are run.
.. versionadded:: 21.3.0
"""
del event_dict["_record"]
del event_dict["_from_structlog"]
return event_dict