Source code for tornado.log

#!/usr/bin/env python
#
# Copyright 2012 Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Logging support for Tornado.

Tornado uses three logger streams:

* ``tornado.access``: Per-request logging for Tornado's HTTP servers (and
  potentially other servers in the future)
* ``tornado.application``: Logging of errors from application code (i.e.
  uncaught exceptions from callbacks)
* ``tornado.general``: General-purpose logging, including any errors
  or warnings from Tornado itself.

These streams may be configured independently using the standard library's
`logging` module.  For example, you may wish to send ``tornado.access`` logs
to a separate file for analysis.
"""
from __future__ import absolute_import, division, print_function, with_statement

import logging
import logging.handlers
import sys

from tornado.escape import _unicode
from tornado.util import unicode_type, basestring_type

try:
    import curses
except ImportError:
    curses = None

# Logger objects for internal tornado use
access_log = logging.getLogger("tornado.access")
app_log = logging.getLogger("tornado.application")
gen_log = logging.getLogger("tornado.general")


def _stderr_supports_color():
    color = False
    if curses and hasattr(sys.stderr, 'isatty') and sys.stderr.isatty():
        try:
            curses.setupterm()
            if curses.tigetnum("colors") > 0:
                color = True
        except Exception:
            pass
    return color


def _safe_unicode(s):
    try:
        return _unicode(s)
    except UnicodeDecodeError:
        return repr(s)


[docs]class LogFormatter(logging.Formatter): """Log formatter used in Tornado. Key features of this formatter are: * Color support when logging to a terminal that supports it. * Timestamps on every log line. * Robust against str/bytes encoding problems. This formatter is enabled automatically by `tornado.options.parse_command_line` (unless ``--logging=none`` is used). """ DEFAULT_FORMAT = '%(color)s[%(levelname)1.1s %(asctime)s %(module)s:%(lineno)d]%(end_color)s %(message)s' DEFAULT_DATE_FORMAT = '%y%m%d %H:%M:%S' DEFAULT_COLORS = { logging.DEBUG: 4, # Blue logging.INFO: 2, # Green logging.WARNING: 3, # Yellow logging.ERROR: 1, # Red } def __init__(self, color=True, fmt=DEFAULT_FORMAT, datefmt=DEFAULT_DATE_FORMAT, colors=DEFAULT_COLORS): r""" :arg bool color: Enables color support. :arg string fmt: Log message format. It will be applied to the attributes dict of log records. The text between ``%(color)s`` and ``%(end_color)s`` will be colored depending on the level if color support is on. :arg dict colors: color mappings from logging level to terminal color code :arg string datefmt: Datetime format. Used for formatting ``(asctime)`` placeholder in ``prefix_fmt``. .. versionchanged:: 3.2 Added ``fmt`` and ``datefmt`` arguments. """ logging.Formatter.__init__(self, datefmt=datefmt) self._fmt = fmt self._colors = {} if color and _stderr_supports_color(): # The curses module has some str/bytes confusion in # python3. Until version 3.2.3, most methods return # bytes, but only accept strings. In addition, we want to # output these strings with the logging module, which # works with unicode strings. The explicit calls to # unicode() below are harmless in python2 but will do the # right conversion in python 3. fg_color = (curses.tigetstr("setaf") or curses.tigetstr("setf") or "") if (3, 0) < sys.version_info < (3, 2, 3): fg_color = unicode_type(fg_color, "ascii") for levelno, code in colors.items(): self._colors[levelno] = unicode_type(curses.tparm(fg_color, code), "ascii") self._normal = unicode_type(curses.tigetstr("sgr0"), "ascii") else: self._normal = '' def format(self, record): try: message = record.getMessage() assert isinstance(message, basestring_type) # guaranteed by logging # Encoding notes: The logging module prefers to work with character # strings, but only enforces that log messages are instances of # basestring. In python 2, non-ascii bytestrings will make # their way through the logging framework until they blow up with # an unhelpful decoding error (with this formatter it happens # when we attach the prefix, but there are other opportunities for # exceptions further along in the framework). # # If a byte string makes it this far, convert it to unicode to # ensure it will make it out to the logs. Use repr() as a fallback # to ensure that all byte strings can be converted successfully, # but don't do it by default so we don't add extra quotes to ascii # bytestrings. This is a bit of a hacky place to do this, but # it's worth it since the encoding errors that would otherwise # result are so useless (and tornado is fond of using utf8-encoded # byte strings whereever possible). record.message = _safe_unicode(message) except Exception as e: record.message = "Bad message (%r): %r" % (e, record.__dict__) record.asctime = self.formatTime(record, self.datefmt) if record.levelno in self._colors: record.color = self._colors[record.levelno] record.end_color = self._normal else: record.color = record.end_color = '' formatted = self._fmt % record.__dict__ if record.exc_info: if not record.exc_text: record.exc_text = self.formatException(record.exc_info) if record.exc_text: # exc_text contains multiple lines. We need to _safe_unicode # each line separately so that non-utf8 bytes don't cause # all the newlines to turn into '\n'. lines = [formatted.rstrip()] lines.extend(_safe_unicode(ln) for ln in record.exc_text.split('\n')) formatted = '\n'.join(lines) return formatted.replace("\n", "\n ")
[docs]def enable_pretty_logging(options=None, logger=None): """Turns on formatted logging output as configured. This is called automaticaly by `tornado.options.parse_command_line` and `tornado.options.parse_config_file`. """ if options is None: from tornado.options import options if options.logging is None or options.logging.lower() == 'none': return if logger is None: logger = logging.getLogger() logger.setLevel(getattr(logging, options.logging.upper())) if options.log_file_prefix: channel = logging.handlers.RotatingFileHandler( filename=options.log_file_prefix, maxBytes=options.log_file_max_size, backupCount=options.log_file_num_backups) channel.setFormatter(LogFormatter(color=False)) logger.addHandler(channel) if (options.log_to_stderr or (options.log_to_stderr is None and not logger.handlers)): # Set up color if we are in a tty and curses is installed channel = logging.StreamHandler() channel.setFormatter(LogFormatter()) logger.addHandler(channel)
def define_logging_options(options=None): if options is None: # late import to prevent cycle from tornado.options import options options.define("logging", default="info", help=("Set the Python log level. If 'none', tornado won't touch the " "logging configuration."), metavar="debug|info|warning|error|none") options.define("log_to_stderr", type=bool, default=None, help=("Send log output to stderr (colorized if possible). " "By default use stderr if --log_file_prefix is not set and " "no other logging is configured.")) options.define("log_file_prefix", type=str, default=None, metavar="PATH", help=("Path prefix for log files. " "Note that if you are running multiple tornado processes, " "log_file_prefix must be different for each of them (e.g. " "include the port number)")) options.define("log_file_max_size", type=int, default=100 * 1000 * 1000, help="max size of log files before rollover") options.define("log_file_num_backups", type=int, default=10, help="number of log files to keep") options.add_parse_callback(enable_pretty_logging)