Source code for structlog.dev

# SPDX-License-Identifier: MIT OR Apache-2.0
# 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.

"""
Helpers that make development with ``structlog`` more pleasant.

See also the narrative documentation in `development`.
"""

import sys
import warnings

from io import StringIO
from typing import Any, Iterable, Optional, TextIO, Type, Union

from ._frames import _format_exception
from .types import (
    EventDict,
    ExceptionRenderer,
    ExcInfo,
    Protocol,
    WrappedLogger,
)


try:
    import colorama
except ImportError:
    colorama = None

try:
    import better_exceptions
except ImportError:
    better_exceptions = None

try:
    import rich

    from rich.console import Console
    from rich.traceback import Traceback
except ImportError:
    rich = None  # type: ignore


__all__ = [
    "ConsoleRenderer",
    "plain_traceback",
    "rich_traceback",
    "better_traceback",
]

_IS_WINDOWS = sys.platform == "win32"

_MISSING = "{who} requires the {package} package installed.  "
_EVENT_WIDTH = 30  # pad the event name to so many characters


def _pad(s: str, length: int) -> str:
    """
    Pads *s* to length *length*.
    """
    missing = length - len(s)

    return s + " " * (missing if missing > 0 else 0)


if colorama is not None:
    RESET_ALL = colorama.Style.RESET_ALL
    BRIGHT = colorama.Style.BRIGHT
    DIM = colorama.Style.DIM
    RED = colorama.Fore.RED
    BLUE = colorama.Fore.BLUE
    CYAN = colorama.Fore.CYAN
    MAGENTA = colorama.Fore.MAGENTA
    YELLOW = colorama.Fore.YELLOW
    GREEN = colorama.Fore.GREEN
    RED_BACK = colorama.Back.RED
else:
    # These are the same values as the colorama color codes. Redefining them
    # here allows users to specify that they want color without having to
    # install colorama, which is only supposed to be necessary in Windows.
    RESET_ALL = "\033[0m"
    BRIGHT = "\033[1m"
    DIM = "\033[2m"
    RED = "\033[31m"
    BLUE = "\033[34m"
    CYAN = "\033[36m"
    MAGENTA = "\033[35m"
    YELLOW = "\033[33m"
    GREEN = "\033[32m"
    RED_BACK = "\033[41m"


if _IS_WINDOWS:  # pragma: no cover
    # On Windows, use colors by default only if colorama is installed.
    _use_colors = colorama is not None
else:
    # On other OSes, use colors by default.
    _use_colors = True


class _Styles(Protocol):
    reset: str
    bright: str
    level_critical: str
    level_exception: str
    level_error: str
    level_warn: str
    level_info: str
    level_debug: str
    level_notset: str

    timestamp: str
    logger_name: str
    kv_key: str
    kv_value: str


Styles = Union[_Styles, Type[_Styles]]


class _ColorfulStyles:
    reset = RESET_ALL
    bright = BRIGHT

    level_critical = RED
    level_exception = RED
    level_error = RED
    level_warn = YELLOW
    level_info = GREEN
    level_debug = GREEN
    level_notset = RED_BACK

    timestamp = DIM
    logger_name = BLUE
    kv_key = CYAN
    kv_value = MAGENTA


class _PlainStyles:
    reset = ""
    bright = ""

    level_critical = ""
    level_exception = ""
    level_error = ""
    level_warn = ""
    level_info = ""
    level_debug = ""
    level_notset = ""

    timestamp = ""
    logger_name = ""
    kv_key = ""
    kv_value = ""


[docs]def plain_traceback(sio: TextIO, exc_info: ExcInfo) -> None: """ "Pretty"-print *exc_info* to *sio* using our own plain formatter. To be passed into `ConsoleRenderer`'s ``exception_formatter`` argument. Used by default if neither ``rich`` not ``better-exceptions`` are present. .. versionadded:: 21.2 """ sio.write("\n" + _format_exception(exc_info))
[docs]def rich_traceback(sio: TextIO, exc_info: ExcInfo) -> None: """ Pretty-print *exc_info* to *sio* using the ``rich`` package. To be passed into `ConsoleRenderer`'s ``exception_formatter`` argument. Used by default if ``rich`` is installed. .. versionadded:: 21.2 """ sio.write("\n") Console(file=sio, color_system="truecolor").print( Traceback.from_exception(*exc_info, show_locals=True) )
[docs]def better_traceback(sio: TextIO, exc_info: ExcInfo) -> None: """ Pretty-print *exc_info* to *sio* using the ``better-exceptions`` package. To be passed into `ConsoleRenderer`'s ``exception_formatter`` argument. Used by default if ``better-exceptions`` is installed and ``rich`` is absent. .. versionadded:: 21.2 """ sio.write("\n" + "".join(better_exceptions.format_exception(*exc_info)))
if rich is not None: default_exception_formatter = rich_traceback elif better_exceptions is not None: default_exception_formatter = better_traceback else: default_exception_formatter = plain_traceback
[docs]class ConsoleRenderer: """ Render ``event_dict`` nicely aligned, possibly in colors, and ordered. If ``event_dict`` contains a true-ish ``exc_info`` key, it will be rendered *after* the log line. If rich_ or better-exceptions_ are present, in colors and with extra context. :param pad_event: Pad the event to this many characters. :param colors: Use colors for a nicer output. `True` by default if colorama_ is installed. :param force_colors: Force colors even for non-tty destinations. Use this option if your logs are stored in a file that is meant to be streamed to the console. :param repr_native_str: When `True`, `repr` is also applied to native strings (i.e. unicode on Python 3 and bytes on Python 2). Setting this to `False` is useful if you want to have human-readable non-ASCII output on Python 2. The ``event`` key is *never* `repr` -ed. :param level_styles: When present, use these styles for colors. This must be a dict from level names (strings) to colorama styles. The default can be obtained by calling `ConsoleRenderer.get_default_level_styles` :param exception_formatter: A callable to render ``exc_infos``. If rich_ or better-exceptions_ are installed, they are used for pretty-printing by default (rich_ taking precedence). You can also manually set it to `plain_traceback`, `better_traceback`, `rich_traceback`, or implement your own. :param sort_keys: Whether to sort keys when formatting. `True` by default. Requires the colorama_ package if *colors* is `True` **on Windows**. .. _colorama: https://pypi.org/project/colorama/ .. _better-exceptions: https://pypi.org/project/better-exceptions/ .. _rich: https://pypi.org/project/rich/ .. versionadded:: 16.0 .. versionadded:: 16.1 *colors* .. versionadded:: 17.1 *repr_native_str* .. versionadded:: 18.1 *force_colors* .. versionadded:: 18.1 *level_styles* .. versionchanged:: 19.2 ``colorama`` now initializes lazily to avoid unwanted initializations as ``ConsoleRenderer`` is used by default. .. versionchanged:: 19.2 Can be pickled now. .. versionchanged:: 20.1 ``colorama`` does not initialize lazily on Windows anymore because it breaks rendering. .. versionchanged:: 21.1 It is additionally possible to set the logger name using the ``logger_name`` key in the ``event_dict``. .. versionadded:: 21.2 *exception_formatter* .. versionchanged:: 21.2 `ConsoleRenderer` now handles the ``exc_info`` event dict key itself. Do **not** use the `structlog.processors.format_exc_info` processor together with `ConsoleRenderer` anymore! It will keep working, but you can't have customize exception formatting and a warning will be raised if you ask for it. .. versionchanged:: 21.2 The colors keyword now defaults to True on non-Windows systems, and either True or False in Windows depending on whether colorama is installed. .. versionadded:: 21.3.0 *sort_keys* """ def __init__( self, pad_event: int = _EVENT_WIDTH, colors: bool = _use_colors, force_colors: bool = False, repr_native_str: bool = False, level_styles: Optional[Styles] = None, exception_formatter: ExceptionRenderer = default_exception_formatter, sort_keys: bool = True, ): styles: Styles if colors: if _IS_WINDOWS: # pragma: no cover # On Windows, we can't do colorful output without colorama. if colorama is None: classname = self.__class__.__name__ raise SystemError( _MISSING.format( who=classname + " with `colors=True`", package="colorama", ) ) # Colorama must be init'd on Windows, but must NOT be # init'd on other OSes, because it can break colors. if force_colors: colorama.deinit() colorama.init(strip=False) else: colorama.init() styles = _ColorfulStyles else: styles = _PlainStyles self._styles = styles self._pad_event = pad_event if level_styles is None: self._level_to_color = self.get_default_level_styles(colors) else: self._level_to_color = level_styles for key in self._level_to_color.keys(): self._level_to_color[key] += styles.bright self._longest_level = len( max(self._level_to_color.keys(), key=lambda e: len(e)) ) self._repr_native_str = repr_native_str self._exception_formatter = exception_formatter self._sort_keys = sort_keys def _repr(self, val: Any) -> str: """ Determine representation of *val* depending on its type & self._repr_native_str. """ if self._repr_native_str is True: return repr(val) if isinstance(val, str): return val else: return repr(val) def __call__( self, logger: WrappedLogger, name: str, event_dict: EventDict ) -> str: sio = StringIO() ts = event_dict.pop("timestamp", None) if ts is not None: sio.write( # can be a number if timestamp is UNIXy self._styles.timestamp + str(ts) + self._styles.reset + " " ) level = event_dict.pop("level", None) if level is not None: sio.write( "[" + self._level_to_color.get(level, "") + _pad(level, self._longest_level) + self._styles.reset + "] " ) # force event to str for compatibility with standard library event = event_dict.pop("event", None) if not isinstance(event, str): event = str(event) if event_dict: event = _pad(event, self._pad_event) + self._styles.reset + " " else: event += self._styles.reset sio.write(self._styles.bright + event) logger_name = event_dict.pop("logger", None) if logger_name is None: logger_name = event_dict.pop("logger_name", None) if logger_name is not None: sio.write( "[" + self._styles.logger_name + self._styles.bright + logger_name + self._styles.reset + "] " ) stack = event_dict.pop("stack", None) exc = event_dict.pop("exception", None) exc_info = event_dict.pop("exc_info", None) event_dict_keys: Iterable[str] = event_dict.keys() if self._sort_keys: event_dict_keys = sorted(event_dict_keys) sio.write( " ".join( self._styles.kv_key + key + self._styles.reset + "=" + self._styles.kv_value + self._repr(event_dict[key]) + self._styles.reset for key in event_dict_keys ) ) if stack is not None: sio.write("\n" + stack) if exc_info or exc is not None: sio.write("\n\n" + "=" * 79 + "\n") if exc_info: if not isinstance(exc_info, tuple): exc_info = sys.exc_info() self._exception_formatter(sio, exc_info) elif exc is not None: if self._exception_formatter is not plain_traceback: warnings.warn( "Remove `format_exc_info` from your processor chain " "if you want pretty exceptions." ) sio.write("\n" + exc) return sio.getvalue()
[docs] @staticmethod def get_default_level_styles(colors: bool = True) -> Any: """ Get the default styles for log levels This is intended to be used with `ConsoleRenderer`'s ``level_styles`` parameter. For example, if you are adding custom levels in your home-grown :func:`~structlog.stdlib.add_log_level` you could do:: my_styles = ConsoleRenderer.get_default_level_styles() my_styles["EVERYTHING_IS_ON_FIRE"] = my_styles["critical"] renderer = ConsoleRenderer(level_styles=my_styles) :param colors: Whether to use colorful styles. This must match the *colors* parameter to `ConsoleRenderer`. Default: `True`. """ styles: Styles if colors: styles = _ColorfulStyles else: styles = _PlainStyles return { "critical": styles.level_critical, "exception": styles.level_exception, "error": styles.level_error, "warn": styles.level_warn, "warning": styles.level_warn, "info": styles.level_info, "debug": styles.level_debug, "notset": styles.level_notset, }
_SENTINEL = object()
[docs]def set_exc_info( logger: WrappedLogger, method_name: str, event_dict: EventDict ) -> EventDict: """ Set ``event_dict["exc_info"] = True`` if *method_name* is ``"exception"``. Do nothing if the name is different or ``exc_info`` is already set. """ if ( method_name != "exception" or event_dict.get("exc_info", _SENTINEL) is not _SENTINEL ): return event_dict event_dict["exc_info"] = True return event_dict