python: add journal backend for the logging framework
Supports Python versions 2.6 through 3.3 (tested on 2.7 and 3.2). See JournalHandler docstring for usage details. [zj: - use send() instead of using sendv() directly - do exception handling like in the logging module - bumped min version to python2.6, since the module does not work with python2.5 anyway ]
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@ -19,6 +19,7 @@
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import traceback as _traceback
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import os as _os
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import logging as _logging
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from syslog import (LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR,
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LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG)
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from ._journal import sendv, stream_fd
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@ -114,3 +115,87 @@ def stream(identifier, priority=LOG_DEBUG, level_prefix=False):
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fd = stream_fd(identifier, priority, level_prefix)
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return _os.fdopen(fd, 'w', 1)
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class JournalHandler(_logging.Handler):
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"""Journal handler class for the Python logging framework.
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Please see the Python logging module documentation for an
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overview: http://docs.python.org/library/logging.html
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To create a custom logger whose messages go only to journal:
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>>> log = logging.getLogger('custom_logger_name')
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>>> log.propagate = False
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>>> log.addHandler(journal.JournalHandler())
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>>> log.warn("Some message: %s", detail)
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Note that by default, message levels INFO and DEBUG are ignored
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by the logging framework. To enable those log levels:
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>>> log.setLevel(logging.DEBUG)
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To attach journal MESSAGE_ID, an extra field is supported:
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>>> log.warn("Message with ID",
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>>> extra={'MESSAGE_ID': '22bb01335f724c959ac4799627d1cb61'})
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To redirect all logging messages to journal regardless of where
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they come from, attach it to the root logger:
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>>> logging.root.addHandler(journal.JournalHandler())
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For more complex configurations when using dictConfig or
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fileConfig, specify 'systemd.journal.JournalHandler' as the
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handler class. Only standard handler configuration options
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are supported: level, formatter, filters.
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The following journal fields will be sent:
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MESSAGE, PRIORITY, THREAD_NAME, CODE_FILE, CODE_LINE,
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CODE_FUNC, LOGGER (name as supplied to getLogger call),
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MESSAGE_ID (optional, see above).
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"""
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def emit(self, record):
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"""Write record as journal event.
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MESSAGE is taken from the message provided by the
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user, and PRIORITY, LOGGER, THREAD_NAME,
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CODE_{FILE,LINE,FUNC} fields are appended
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automatically. In addition, record.MESSAGE_ID will be
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used if present.
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"""
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try:
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msg = self.format(record)
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pri = self.mapPriority(record.levelno)
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mid = getattr(record, 'MESSAGE_ID', None)
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send(msg,
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MESSAGE_ID=mid,
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PRIORITY=format(pri),
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LOGGER=record.name,
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THREAD_NAME=record.threadName,
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CODE_FILE=record.pathname,
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CODE_LINE=record.lineno,
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CODE_FUNC=record.funcName)
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except Exception:
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self.handleError(record)
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@staticmethod
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def mapPriority(levelno):
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"""Map logging levels to journald priorities.
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Since Python log level numbers are "sparse", we have
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to map numbers in between the standard levels too.
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"""
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if levelno <= _logging.DEBUG:
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return LOG_DEBUG
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elif levelno <= _logging.INFO:
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return LOG_INFO
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elif levelno <= _logging.WARNING:
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return LOG_WARNING
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elif levelno <= _logging.ERROR:
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return LOG_ERR
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elif levelno <= _logging.CRITICAL:
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return LOG_CRIT
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else:
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return LOG_ALERT
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