root / lib / utils / log.py @ aa0cc3e5
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# Copyright (C) 2006, 2007, 2010, 2011 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Utility functions for logging.
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"""
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import logging |
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import logging.handlers |
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from ganeti import constants |
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class _ReopenableLogHandler(logging.handlers.BaseRotatingHandler): |
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"""Log handler with ability to reopen log file on request.
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In combination with a SIGHUP handler this class can reopen the log file on
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user request.
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"""
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def __init__(self, filename): |
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"""Initializes this class.
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@type filename: string
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@param filename: Path to logfile
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"""
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logging.handlers.BaseRotatingHandler.__init__(self, filename, "a") |
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assert self.encoding is None, "Encoding not supported for logging" |
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assert not hasattr(self, "_reopen"), "Base class has '_reopen' attribute" |
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self._reopen = False |
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def shouldRollover(self, _): # pylint: disable-msg=C0103 |
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"""Determine whether log file should be reopened.
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"""
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return self._reopen or not self.stream |
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def doRollover(self): # pylint: disable-msg=C0103 |
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"""Reopens the log file.
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"""
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if self.stream: |
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self.stream.flush()
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self.stream.close()
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self.stream = None |
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# Reopen file
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# TODO: Handle errors?
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self.stream = open(self.baseFilename, "a") |
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def RequestReopen(self): |
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"""Register a request to reopen the file.
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The file will be reopened before writing the next log record.
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"""
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self._reopen = True |
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def _LogErrorsToConsole(base): |
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"""Create wrapper class writing errors to console.
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This needs to be in a function for unittesting.
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"""
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class wrapped(base): # pylint: disable-msg=C0103 |
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"""Log handler that doesn't fallback to stderr.
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When an error occurs while writing on the logfile, logging.FileHandler
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tries to log on stderr. This doesn't work in Ganeti since stderr is
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redirected to a logfile. This class avoids failures by reporting errors to
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/dev/console.
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"""
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def __init__(self, console, *args, **kwargs): |
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"""Initializes this class.
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@type console: file-like object or None
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@param console: Open file-like object for console
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"""
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base.__init__(self, *args, **kwargs)
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assert not hasattr(self, "_console") |
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self._console = console
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def handleError(self, record): # pylint: disable-msg=C0103 |
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"""Handle errors which occur during an emit() call.
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Try to handle errors with FileHandler method, if it fails write to
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/dev/console.
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"""
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try:
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base.handleError(record) |
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except Exception: # pylint: disable-msg=W0703 |
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if self._console: |
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try:
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# Ignore warning about "self.format", pylint: disable-msg=E1101
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self._console.write("Cannot log message:\n%s\n" % |
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self.format(record))
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except Exception: # pylint: disable-msg=W0703 |
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# Log handler tried everything it could, now just give up
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pass
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return wrapped
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#: Custom log handler for writing to console with a reopenable handler
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_LogHandler = _LogErrorsToConsole(_ReopenableLogHandler) |
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def _GetLogFormatter(program, multithreaded, debug, syslog): |
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"""Build log formatter.
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@param program: Program name
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@param multithreaded: Whether to add thread name to log messages
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@param debug: Whether to enable debug messages
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@param syslog: Whether the formatter will be used for syslog
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"""
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parts = [] |
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if syslog:
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parts.append(program + "[%(process)d]:")
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else:
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parts.append("%(asctime)s: " + program + " pid=%(process)d") |
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if multithreaded:
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if syslog:
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parts.append(" (%(threadName)s)")
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else:
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parts.append("/%(threadName)s")
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# Add debug info for non-syslog loggers
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if debug and not syslog: |
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parts.append(" %(module)s:%(lineno)s")
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# Ses, we do want the textual level, as remote syslog will probably lose the
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# error level, and it's easier to grep for it.
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parts.append(" %(levelname)s %(message)s")
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return logging.Formatter("".join(parts)) |
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def SetupLogging(logfile, debug=0, stderr_logging=False, program="", |
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multithreaded=False, syslog=constants.SYSLOG_USAGE,
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console_logging=False):
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"""Configures the logging module.
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@type logfile: str
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@param logfile: the filename to which we should log
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@type debug: integer
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@param debug: if greater than zero, enable debug messages, otherwise
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only those at C{INFO} and above level
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@type stderr_logging: boolean
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@param stderr_logging: whether we should also log to the standard error
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@type program: str
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@param program: the name under which we should log messages
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@type multithreaded: boolean
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@param multithreaded: if True, will add the thread name to the log file
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@type syslog: string
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@param syslog: one of 'no', 'yes', 'only':
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- if no, syslog is not used
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- if yes, syslog is used (in addition to file-logging)
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- if only, only syslog is used
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@type console_logging: boolean
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@param console_logging: if True, will use a FileHandler which falls back to
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the system console if logging fails
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@raise EnvironmentError: if we can't open the log file and
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syslog/stderr logging is disabled
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"""
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formatter = _GetLogFormatter(program, multithreaded, debug, False)
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syslog_fmt = _GetLogFormatter(program, multithreaded, debug, True)
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root_logger = logging.getLogger("")
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root_logger.setLevel(logging.NOTSET) |
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# Remove all previously setup handlers
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for handler in root_logger.handlers: |
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handler.close() |
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root_logger.removeHandler(handler) |
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if stderr_logging:
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stderr_handler = logging.StreamHandler() |
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stderr_handler.setFormatter(formatter) |
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if debug:
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stderr_handler.setLevel(logging.NOTSET) |
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else:
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stderr_handler.setLevel(logging.CRITICAL) |
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root_logger.addHandler(stderr_handler) |
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if syslog in (constants.SYSLOG_YES, constants.SYSLOG_ONLY): |
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facility = logging.handlers.SysLogHandler.LOG_DAEMON |
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syslog_handler = logging.handlers.SysLogHandler(constants.SYSLOG_SOCKET, |
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facility) |
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syslog_handler.setFormatter(syslog_fmt) |
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# Never enable debug over syslog
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syslog_handler.setLevel(logging.INFO) |
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root_logger.addHandler(syslog_handler) |
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if syslog != constants.SYSLOG_ONLY:
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# this can fail, if the logging directories are not setup or we have
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# a permisssion problem; in this case, it's best to log but ignore
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# the error if stderr_logging is True, and if false we re-raise the
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# exception since otherwise we could run but without any logs at all
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try:
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if console_logging:
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logfile_handler = _LogHandler(open(constants.DEV_CONSOLE, "a"), logfile) |
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else:
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logfile_handler = _ReopenableLogHandler(logfile) |
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except EnvironmentError: |
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if stderr_logging or syslog == constants.SYSLOG_YES: |
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logging.exception("Failed to enable logging to file '%s'", logfile)
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else:
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# we need to re-raise the exception
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raise
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logfile_handler.setFormatter(formatter) |
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if debug:
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logfile_handler.setLevel(logging.DEBUG) |
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else:
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logfile_handler.setLevel(logging.INFO) |
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root_logger.addHandler(logfile_handler) |