Mercurial > repos > shellac > sam_consensus_v3
diff env/lib/python3.9/site-packages/coloredlogs/syslog.py @ 0:4f3585e2f14b draft default tip
"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"
author | shellac |
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date | Mon, 22 Mar 2021 18:12:50 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/env/lib/python3.9/site-packages/coloredlogs/syslog.py Mon Mar 22 18:12:50 2021 +0000 @@ -0,0 +1,292 @@ +# Easy to use system logging for Python's logging module. +# +# Author: Peter Odding <peter@peterodding.com> +# Last Change: December 10, 2020 +# URL: https://coloredlogs.readthedocs.io + +""" +Easy to use UNIX system logging for Python's :mod:`logging` module. + +Admittedly system logging has little to do with colored terminal output, however: + +- The `coloredlogs` package is my attempt to do Python logging right and system + logging is an important part of that equation. + +- I've seen a surprising number of quirks and mistakes in system logging done + in Python, for example including ``%(asctime)s`` in a format string (the + system logging daemon is responsible for adding timestamps and thus you end + up with duplicate timestamps that make the logs awful to read :-). + +- The ``%(programname)s`` filter originated in my system logging code and I + wanted it in `coloredlogs` so the step to include this module wasn't that big. + +- As a bonus this Python module now has a test suite and proper documentation. + +So there :-P. Go take a look at :func:`enable_system_logging()`. +""" + +# Standard library modules. +import logging +import logging.handlers +import os +import socket +import sys + +# External dependencies. +from humanfriendly import coerce_boolean +from humanfriendly.compat import on_macos, on_windows + +# Modules included in our package. +from coloredlogs import ( + DEFAULT_LOG_LEVEL, + ProgramNameFilter, + adjust_level, + find_program_name, + level_to_number, + replace_handler, +) + +LOG_DEVICE_MACOSX = '/var/run/syslog' +"""The pathname of the log device on Mac OS X (a string).""" + +LOG_DEVICE_UNIX = '/dev/log' +"""The pathname of the log device on Linux and most other UNIX systems (a string).""" + +DEFAULT_LOG_FORMAT = '%(programname)s[%(process)d]: %(levelname)s %(message)s' +""" +The default format for log messages sent to the system log (a string). + +The ``%(programname)s`` format requires :class:`~coloredlogs.ProgramNameFilter` +but :func:`enable_system_logging()` takes care of this for you. + +The ``name[pid]:`` construct (specifically the colon) in the format allows +rsyslogd_ to extract the ``$programname`` from each log message, which in turn +allows configuration files in ``/etc/rsyslog.d/*.conf`` to filter these log +messages to a separate log file (if the need arises). + +.. _rsyslogd: https://en.wikipedia.org/wiki/Rsyslog +""" + +# Initialize a logger for this module. +logger = logging.getLogger(__name__) + + +class SystemLogging(object): + + """Context manager to enable system logging.""" + + def __init__(self, *args, **kw): + """ + Initialize a :class:`SystemLogging` object. + + :param args: Positional arguments to :func:`enable_system_logging()`. + :param kw: Keyword arguments to :func:`enable_system_logging()`. + """ + self.args = args + self.kw = kw + self.handler = None + + def __enter__(self): + """Enable system logging when entering the context.""" + if self.handler is None: + self.handler = enable_system_logging(*self.args, **self.kw) + return self.handler + + def __exit__(self, exc_type=None, exc_value=None, traceback=None): + """ + Disable system logging when leaving the context. + + .. note:: If an exception is being handled when we leave the context a + warning message including traceback is logged *before* system + logging is disabled. + """ + if self.handler is not None: + if exc_type is not None: + logger.warning("Disabling system logging due to unhandled exception!", exc_info=True) + (self.kw.get('logger') or logging.getLogger()).removeHandler(self.handler) + self.handler = None + + +def enable_system_logging(programname=None, fmt=None, logger=None, reconfigure=True, **kw): + """ + Redirect :mod:`logging` messages to the system log (e.g. ``/var/log/syslog``). + + :param programname: The program name to embed in log messages (a string, defaults + to the result of :func:`~coloredlogs.find_program_name()`). + :param fmt: The log format for system log messages (a string, defaults to + :data:`DEFAULT_LOG_FORMAT`). + :param logger: The logger to which the :class:`~logging.handlers.SysLogHandler` + should be connected (defaults to the root logger). + :param level: The logging level for the :class:`~logging.handlers.SysLogHandler` + (defaults to :data:`.DEFAULT_LOG_LEVEL`). This value is coerced + using :func:`~coloredlogs.level_to_number()`. + :param reconfigure: If :data:`True` (the default) multiple calls to + :func:`enable_system_logging()` will each override + the previous configuration. + :param kw: Refer to :func:`connect_to_syslog()`. + :returns: A :class:`~logging.handlers.SysLogHandler` object or + :data:`None`. If an existing handler is found and `reconfigure` + is :data:`False` the existing handler object is returned. If the + connection to the system logging daemon fails :data:`None` is + returned. + + As of release 15.0 this function uses :func:`is_syslog_supported()` to + check whether system logging is supported and appropriate before it's + enabled. + + .. note:: When the logger's effective level is too restrictive it is + relaxed (refer to `notes about log levels`_ for details). + """ + # Check whether system logging is supported / appropriate. + if not is_syslog_supported(): + return None + # Provide defaults for omitted arguments. + programname = programname or find_program_name() + logger = logger or logging.getLogger() + fmt = fmt or DEFAULT_LOG_FORMAT + level = level_to_number(kw.get('level', DEFAULT_LOG_LEVEL)) + # Check whether system logging is already enabled. + handler, logger = replace_handler(logger, match_syslog_handler, reconfigure) + # Make sure reconfiguration is allowed or not relevant. + if not (handler and not reconfigure): + # Create a system logging handler. + handler = connect_to_syslog(**kw) + # Make sure the handler was successfully created. + if handler: + # Enable the use of %(programname)s. + ProgramNameFilter.install(handler=handler, fmt=fmt, programname=programname) + # Connect the formatter, handler and logger. + handler.setFormatter(logging.Formatter(fmt)) + logger.addHandler(handler) + # Adjust the level of the selected logger. + adjust_level(logger, level) + return handler + + +def connect_to_syslog(address=None, facility=None, level=None): + """ + Create a :class:`~logging.handlers.SysLogHandler`. + + :param address: The device file or network address of the system logging + daemon (a string or tuple, defaults to the result of + :func:`find_syslog_address()`). + :param facility: Refer to :class:`~logging.handlers.SysLogHandler`. + Defaults to ``LOG_USER``. + :param level: The logging level for the :class:`~logging.handlers.SysLogHandler` + (defaults to :data:`.DEFAULT_LOG_LEVEL`). This value is coerced + using :func:`~coloredlogs.level_to_number()`. + :returns: A :class:`~logging.handlers.SysLogHandler` object or :data:`None` (if the + system logging daemon is unavailable). + + The process of connecting to the system logging daemon goes as follows: + + - The following two socket types are tried (in decreasing preference): + + 1. :data:`~socket.SOCK_RAW` avoids truncation of log messages but may + not be supported. + 2. :data:`~socket.SOCK_STREAM` (TCP) supports longer messages than the + default (which is UDP). + """ + if not address: + address = find_syslog_address() + if facility is None: + facility = logging.handlers.SysLogHandler.LOG_USER + if level is None: + level = DEFAULT_LOG_LEVEL + for socktype in socket.SOCK_RAW, socket.SOCK_STREAM, None: + kw = dict(facility=facility, address=address) + if socktype is not None: + kw['socktype'] = socktype + try: + handler = logging.handlers.SysLogHandler(**kw) + except IOError: + # IOError is a superclass of socket.error which can be raised if the system + # logging daemon is unavailable. + pass + else: + handler.setLevel(level_to_number(level)) + return handler + + +def find_syslog_address(): + """ + Find the most suitable destination for system log messages. + + :returns: The pathname of a log device (a string) or an address/port tuple as + supported by :class:`~logging.handlers.SysLogHandler`. + + On Mac OS X this prefers :data:`LOG_DEVICE_MACOSX`, after that :data:`LOG_DEVICE_UNIX` + is checked for existence. If both of these device files don't exist the default used + by :class:`~logging.handlers.SysLogHandler` is returned. + """ + if sys.platform == 'darwin' and os.path.exists(LOG_DEVICE_MACOSX): + return LOG_DEVICE_MACOSX + elif os.path.exists(LOG_DEVICE_UNIX): + return LOG_DEVICE_UNIX + else: + return 'localhost', logging.handlers.SYSLOG_UDP_PORT + + +def is_syslog_supported(): + """ + Determine whether system logging is supported. + + :returns: + + :data:`True` if system logging is supported and can be enabled, + :data:`False` if system logging is not supported or there are good + reasons for not enabling it. + + The decision making process here is as follows: + + Override + If the environment variable ``$COLOREDLOGS_SYSLOG`` is set it is evaluated + using :func:`~humanfriendly.coerce_boolean()` and the resulting value + overrides the platform detection discussed below, this allows users to + override the decision making process if they disagree / know better. + + Linux / UNIX + On systems that are not Windows or MacOS (see below) we assume UNIX which + means either syslog is available or sending a bunch of UDP packets to + nowhere won't hurt anyone... + + Microsoft Windows + Over the years I've had multiple reports of :pypi:`coloredlogs` spewing + extremely verbose errno 10057 warning messages to the console (once for + each log message I suppose) so I now assume it a default that + "syslog-style system logging" is not generally available on Windows. + + Apple MacOS + There's cPython issue `#38780`_ which seems to result in a fatal exception + when the Python interpreter shuts down. This is (way) worse than not + having system logging enabled. The error message mentioned in `#38780`_ + has actually been following me around for years now, see for example: + + - https://github.com/xolox/python-rotate-backups/issues/9 mentions Docker + images implying Linux, so not strictly the same as `#38780`_. + + - https://github.com/xolox/python-npm-accel/issues/4 is definitely related + to `#38780`_ and is what eventually prompted me to add the + :func:`is_syslog_supported()` logic. + + .. _#38780: https://bugs.python.org/issue38780 + """ + override = os.environ.get("COLOREDLOGS_SYSLOG") + if override is not None: + return coerce_boolean(override) + else: + return not (on_windows() or on_macos()) + + +def match_syslog_handler(handler): + """ + Identify system logging handlers. + + :param handler: The :class:`~logging.Handler` class to check. + :returns: :data:`True` if the handler is a + :class:`~logging.handlers.SysLogHandler`, + :data:`False` otherwise. + + This function can be used as a callback for :func:`.find_handler()`. + """ + return isinstance(handler, logging.handlers.SysLogHandler)