499

我正在使用 Python 的日志记录模块将一些调试字符串记录到一个运行良好的文件中。现在另外,我想使用这个模块将字符串打印到标准输出。我该怎么做呢?为了将我的字符串记录到文件中,我使用以下代码:

import logging
import logging.handlers
logger = logging.getLogger("")
logger.setLevel(logging.DEBUG)
handler = logging.handlers.RotatingFileHandler(
    LOGFILE, maxBytes=(1048576*5), backupCount=7
)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler.setFormatter(formatter)
logger.addHandler(handler)

然后调用一个记录器函数

logger.debug("I am written to the file")

在这里感谢您的帮助!

4

8 回答 8

605

只需获取根记录器的句柄并添加StreamHandler. 对标准错误的StreamHandler写入。不确定您是否真的需要 stdout 而不是 stderr,但这是我在设置 Python 记录器时使用的,我也添加了FileHandler。然后我所有的日志都去这两个地方(这听起来像你想要的)。

import logging
logging.getLogger().addHandler(logging.StreamHandler())

如果要输出 tostdout而不是stderr,只需将其指定给StreamHandler构造函数即可。

import sys
# ...
logging.getLogger().addHandler(logging.StreamHandler(sys.stdout))

您也可以在其中添加一个Formatter,这样您的所有日志行都有一个共同的标题。

IE:

import logging
logFormatter = logging.Formatter("%(asctime)s [%(threadName)-12.12s] [%(levelname)-5.5s]  %(message)s")
rootLogger = logging.getLogger()

fileHandler = logging.FileHandler("{0}/{1}.log".format(logPath, fileName))
fileHandler.setFormatter(logFormatter)
rootLogger.addHandler(fileHandler)

consoleHandler = logging.StreamHandler()
consoleHandler.setFormatter(logFormatter)
rootLogger.addHandler(consoleHandler)

打印为以下格式:

2012-12-05 16:58:26,618 [MainThread  ] [INFO ]  my message
于 2012-12-05T22:43:00.510 回答
468

logging.basicConfig()从 Python 3.3 开始可以使用关键字参数handlers,这大大简化了日志设置,尤其是在使用相同的格式化程序设置多个处理程序时:

handlers– 如果指定,这应该是已创建的处理程序的可迭代,以添加到根记录器。任何尚未设置格式化程序的处理程序都将被分配在此函数中创建的默认格式化程序。

因此,整个设置可以通过一个这样的调用来完成:

import logging

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
    handlers=[
        logging.FileHandler("debug.log"),
        logging.StreamHandler()
    ]
)

(或者根据原始问题的要求加上import sys+ StreamHandler(sys.stdout)- StreamHandler 的默认值是写入标准错误。如果您想自定义日志格式并添加文件名/行、线程信息等内容,请查看LogRecord 属性。)

上面的设置只需要在脚本开头附近进行一次。您可以稍后使用代码库中所有其他位置的日志记录,如下所示:

logging.info('Useful message')
logging.error('Something bad happened')
...

注意:如果它不起作用,其他人可能已经以不同的方式初始化了日志系统。评论建议logging.root.handlers = []在调用之前做basicConfig()

于 2017-09-07T14:17:31.037 回答
85

添加不带参数的 StreamHandler 会转到 stderr 而不是 stdout。如果其他进程依赖于标准输出转储(即在编写 NRPE 插件时),请确保明确指定标准输出,否则您可能会遇到一些意想不到的麻烦。

这是一个重用假设值和问题中的 LOGFILE 的快速示例:

import logging
from logging.handlers import RotatingFileHandler
from logging import handlers
import sys

log = logging.getLogger('')
log.setLevel(logging.DEBUG)
format = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")

ch = logging.StreamHandler(sys.stdout)
ch.setFormatter(format)
log.addHandler(ch)

fh = handlers.RotatingFileHandler(LOGFILE, maxBytes=(1048576*5), backupCount=7)
fh.setFormatter(format)
log.addHandler(fh)
于 2014-09-24T02:49:04.703 回答
24

这是一个完整的、包装精美的解决方案,基于Waterboy 的回答和其他各种来源。它支持记录到控制台和日志文件,允许不同的日志级别设置,提供彩色输出并且易于配置(也可作为Gist提供):

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# -------------------------------------------------------------------------------
#                                                                               -
#  Python dual-logging setup (console and log file),                            -
#  supporting different log levels and colorized output                         -
#                                                                               -
#  Created by Fonic <https://github.com/fonic>                                  -
#  Date: 04/05/20                                                               -
#                                                                               -
#  Based on:                                                                    -
#  https://stackoverflow.com/a/13733863/1976617                                 -
#  https://uran198.github.io/en/python/2016/07/12/colorful-python-logging.html  -
#  https://en.wikipedia.org/wiki/ANSI_escape_code#Colors                        -
#                                                                               -
# -------------------------------------------------------------------------------

# Imports
import os
import sys
import logging

# Logging formatter supporting colorized output
class LogFormatter(logging.Formatter):

    COLOR_CODES = {
        logging.CRITICAL: "\033[1;35m", # bright/bold magenta
        logging.ERROR:    "\033[1;31m", # bright/bold red
        logging.WARNING:  "\033[1;33m", # bright/bold yellow
        logging.INFO:     "\033[0;37m", # white / light gray
        logging.DEBUG:    "\033[1;30m"  # bright/bold black / dark gray
    }

    RESET_CODE = "\033[0m"

    def __init__(self, color, *args, **kwargs):
        super(LogFormatter, self).__init__(*args, **kwargs)
        self.color = color

    def format(self, record, *args, **kwargs):
        if (self.color == True and record.levelno in self.COLOR_CODES):
            record.color_on  = self.COLOR_CODES[record.levelno]
            record.color_off = self.RESET_CODE
        else:
            record.color_on  = ""
            record.color_off = ""
        return super(LogFormatter, self).format(record, *args, **kwargs)

# Setup logging
def setup_logging(console_log_output, console_log_level, console_log_color, logfile_file, logfile_log_level, logfile_log_color, log_line_template):

    # Create logger
    # For simplicity, we use the root logger, i.e. call 'logging.getLogger()'
    # without name argument. This way we can simply use module methods for
    # for logging throughout the script. An alternative would be exporting
    # the logger, i.e. 'global logger; logger = logging.getLogger("<name>")'
    logger = logging.getLogger()

    # Set global log level to 'debug' (required for handler levels to work)
    logger.setLevel(logging.DEBUG)

    # Create console handler
    console_log_output = console_log_output.lower()
    if (console_log_output == "stdout"):
        console_log_output = sys.stdout
    elif (console_log_output == "stderr"):
        console_log_output = sys.stderr
    else:
        print("Failed to set console output: invalid output: '%s'" % console_log_output)
        return False
    console_handler = logging.StreamHandler(console_log_output)

    # Set console log level
    try:
        console_handler.setLevel(console_log_level.upper()) # only accepts uppercase level names
    except:
        print("Failed to set console log level: invalid level: '%s'" % console_log_level)
        return False

    # Create and set formatter, add console handler to logger
    console_formatter = LogFormatter(fmt=log_line_template, color=console_log_color)
    console_handler.setFormatter(console_formatter)
    logger.addHandler(console_handler)

    # Create log file handler
    try:
        logfile_handler = logging.FileHandler(logfile_file)
    except Exception as exception:
        print("Failed to set up log file: %s" % str(exception))
        return False

    # Set log file log level
    try:
        logfile_handler.setLevel(logfile_log_level.upper()) # only accepts uppercase level names
    except:
        print("Failed to set log file log level: invalid level: '%s'" % logfile_log_level)
        return False

    # Create and set formatter, add log file handler to logger
    logfile_formatter = LogFormatter(fmt=log_line_template, color=logfile_log_color)
    logfile_handler.setFormatter(logfile_formatter)
    logger.addHandler(logfile_handler)

    # Success
    return True

# Main function
def main():

    # Setup logging
    script_name = os.path.splitext(os.path.basename(sys.argv[0]))[0]
    if (not setup_logging(console_log_output="stdout", console_log_level="warning", console_log_color=True,
                        logfile_file=script_name + ".log", logfile_log_level="debug", logfile_log_color=False,
                        log_line_template="%(color_on)s[%(created)d] [%(threadName)s] [%(levelname)-8s] %(message)s%(color_off)s")):
        print("Failed to setup logging, aborting.")
        return 1

    # Log some messages
    logging.debug("Debug message")
    logging.info("Info message")
    logging.warning("Warning message")
    logging.error("Error message")
    logging.critical("Critical message")

# Call main function
if (__name__ == "__main__"):
    sys.exit(main())

关于 Microsoft Windows 的注意事项:
要在 Microsoft Windows 上实际显示颜色,还需要执行其他步骤。有两个选项(均在 Microsoft Windows 10 上成功测试):

1) 使用以下代码启用 ANSI 终端模式(通过设置标志使终端能够解释转义序列ENABLE_VIRTUAL_TERMINAL_PROCESSING;更多信息请参见此处此处此处此处):

# Enable ANSI terminal mode on Microsoft Windows
def windows_enable_ansi_terminal_mode():
    if (sys.platform != "win32"):
        return None
    try:
        import ctypes
        kernel32 = ctypes.windll.kernel32
        result = kernel32.SetConsoleMode(kernel32.GetStdHandle(-11), 7)
        if (result == 0): raise Exception
        return True
    except:
        return False

2) 使用 Python 包colorama(过滤发送到stdoutstderr的输出并将转义序列转换为本地 Windows API 调用):

import colorama
colorama.init()
于 2020-04-05T14:00:24.983 回答
20

在设置任何其他处理程序或记录任何消息之前作为参数运行basicConfig,或者手动添加一个将消息推送到标准输出到根记录器(或您想要的任何其他记录器,就此而言)。stream=sys.stdoutStreamHandler

于 2012-12-05T22:37:43.397 回答
13

记录到不同级别和格式stdoutrotating file

import logging
import logging.handlers
import sys

if __name__ == "__main__":

    # Change root logger level from WARNING (default) to NOTSET in order for all messages to be delegated.
    logging.getLogger().setLevel(logging.NOTSET)

    # Add stdout handler, with level INFO
    console = logging.StreamHandler(sys.stdout)
    console.setLevel(logging.INFO)
    formater = logging.Formatter('%(name)-13s: %(levelname)-8s %(message)s')
    console.setFormatter(formater)
    logging.getLogger().addHandler(console)

    # Add file rotating handler, with level DEBUG
    rotatingHandler = logging.handlers.RotatingFileHandler(filename='rotating.log', maxBytes=1000, backupCount=5)
    rotatingHandler.setLevel(logging.DEBUG)
    formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    rotatingHandler.setFormatter(formatter)
    logging.getLogger().addHandler(rotatingHandler)

    log = logging.getLogger("app." + __name__)

    log.debug('Debug message, should only appear in the file.')
    log.info('Info message, should appear in file and stdout.')
    log.warning('Warning message, should appear in file and stdout.')
    log.error('Error message, should appear in file and stdout.')
于 2019-12-20T22:13:23.700 回答
7

在多个 Python 包中一遍又一遍地使用 Waterboy 的代码后,我最终将其转换为一个小的独立 Python 包,您可以在此处找到它:

https://github.com/acschaefer/duallog

该代码有据可查且易于使用。只需下载.py文件并将其包含在您的项目中,或通过pip install duallog.

于 2018-10-27T00:58:28.883 回答
-5

对于 2.7,请尝试以下操作:

fh = logging.handlers.RotatingFileHandler(LOGFILE, maxBytes=(1048576*5), backupCount=7)
于 2016-07-19T22:57:24.653 回答