diff env/lib/python3.9/site-packages/coloredlogs/syslog.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /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 <[e-mail]>
+# 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)