禁用某些消息的格式

Question

我正在使用 pythons 日志库开发数据分析管道。我正在记录有关正在运行的步骤的自定义消息以及调用程序的原始输出。我使用sh.py 来简化shell 命令的调用。它让我可以定义一个回调函数来处理STDOUT/STDERR 的每一行。

我希望能够定义我的回调函数以将每一行记录到日志文件中而不需要格式化（这些程序输出很多行）：

log.info("Starting %s run on %s", program_name, file_name)

def call_back(line):
    log.info.NOFORMAT(line)  # do the no format logging

sh.program(args, _out=call_back)

log.info("Finished running %s", program_name)

我生成的日志文件将如下所示：

"""<br>
2016-01-22|{INFO}: Starting $SOME_PROGRAM$ on $SOME_FILE$<br>
program_output_line<br>
program_output_line<br>
program_output_line<br>
program_output_line<br>
program_output_line<br>
2016-01-22|{INFO}: Finished running $SOME_PROGRAM$<br>
"""

有谁知道我如何做到这一点？

Answer 1

您可以为Logger 使用的处理程序设置logging.Formatter 对象。它应该实现format(record) 方法，该方法将返回实际显示的字符串。

import sh
import logging

class MyFormatter(logging.Formatter):
    def __init__(self, *args, **kwargs):
        logging.Formatter.__init__(self, *args, **kwargs)
        self._enableFormatFlag = True

    def enableFormat(self):
        self._enableFormatFlag = True
    def disableFormat(self):
        self._enableFormatFlag = False

    def format(self, record):
        if self._enableFormatFlag:
            return logging.Formatter.format(self, record)
        else:
            return record.getMessage()

logger = logging.getLogger('myapp')
logger.setLevel(logging.INFO)
handler = logging.StreamHandler()
logger.addHandler(handler)
formatter = MyFormatter(fmt="prefix[%(message)s]suffix")
handler.setFormatter(formatter)


def callback(line):
    logger.info(line.strip())

logger.info("Will start program")
formatter.disableFormat()
sh.ls(['-l'],_out=callback)
formatter.enableFormat()
logger.info("Finished program")

PS：我之前的回答是关于获取回调，抱歉。

Answer 2

您可以查看 logging.config https://docs.python.org/2/library/logging.config.html

基本上，您将定义一个专用记录器，该记录器写入与根记录器相同的文件，但使用精简的格式化程序，如format=%(message)s。然后，在 call_back 中，您将显式获取该记录器：logging.getlogger(logger_name)。

Answer 3

您可以通过扩展 logging.Formatter 类来做到这一点。如果日志消息附带可选的元数据 simple=True - 则不会为该特定消息呈现格式。

class ConditionalFormatter(logging.Formatter):
    def format(self, record):
        if hasattr(record, 'simple') and record.simple:
            return record.getMessage()
        else:
            return logging.Formatter.format(self, record)


rotating_file_formatter = ConditionalFormatter('%(asctime)s %(levelname)s - %(message)s')
rotating_file.setFormatter(rotating_file_formatter)
# ...

• 带格式

  logging.info("starting application ...")
  

  日志输出：

  2020-05-01 19:38:05,337 INFO - starting application ...
  

• 不格式化

  logging.info("starting application ...", extra={'simple': True})
  

  日志输出：

  starting application ...
  

---

完整示例

在此脚本中，我使用控制台日志记录和文件日志记录。在一般日志中，我调用了一个命令 ls -ahl / 并将其所有输出直接传送到日志而不进行格式化：

#!/usr/bin/env python3

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


def initialize_logger(log_file_path):
    rotating_file = RotatingFileHandler(log_file_path, mode='a', maxBytes=5 * 1024 * 1024, backupCount=5, encoding=None, delay=0)

    class ConditionalFormatter(logging.Formatter):
        def format(self, record):
            if hasattr(record, 'simple') and record.simple:
                return record.getMessage()
            else:
                return logging.Formatter.format(self, record)

    rotating_file_formatter = ConditionalFormatter('%(asctime)s %(levelname)s - %(message)s')
    rotating_file.setFormatter(rotating_file_formatter)
    rotating_file.setLevel(logging.DEBUG)

    console_logger = logging.StreamHandler(sys.stdout)
    console_logger_formatter = logging.Formatter('%(message)s')
    console_logger.setFormatter(console_logger_formatter)
    console_logger.setLevel(logging.INFO)

    root_logger = logging.getLogger()
    root_logger.setLevel(logging.DEBUG)
    root_logger.addHandler(rotating_file)
    root_logger.addHandler(console_logger)


def main():
    initialize_logger('/var/log/my-app.log')
    logging.info('starting application ...')

    command = ["ls", "-ahl"]
    working_directory = '/'
    logging.info(f'running {command} ...')
    process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, cwd=working_directory)

    with process.stdout:
        for line in iter(process.stdout.readline, b''):
            line = line.decode('utf-8')
            line = line.strip()
            logging.debug(line, extra={'simple': True})

    exit_code = process.wait()
    if exit_code == 0:
        logging.debug(f'command "{command}" finished successfully')
    else:
        logging.debug(f'command "{command}" failed with exit code {exit_code}')

    logging.info('stopping application')


if __name__ == '__main__':
    main()

标准输出：

starting application ...
running ['ls', '-ahl'] ...
stopping application

输出文件/var/log/my-app.log:

2020-05-01 19:48:06,347 INFO - starting application ...
2020-05-01 19:48:06,347 INFO - running ['ls', '-ahl', '/'] ...
total 112K
drwxr-xr-x  25 root root 4.0K Apr 30 06:55 .
drwxr-xr-x  25 root root 4.0K Apr 30 06:55 ..
drwxr-xr-x   2 root root 4.0K Mar 31 06:39 bin
drwxr-xr-x   3 root root 4.0K May  1 06:02 boot
drwxrwxr-x   2 root root 4.0K Oct 11  2018 cdrom
drwxr-xr-x  20 root root 4.2K Apr 30 06:54 dev
drwxr-xr-x 154 root root  12K Apr 30 06:54 etc
drwxr-xr-x   3 root root 4.0K Oct 11  2018 home
lrwxrwxrwx   1 root root   33 Apr 30 06:55 initrd.img -> boot/initrd.img-4.15.0-99-generic
lrwxrwxrwx   1 root root   33 Apr 30 06:55 initrd.img.old -> boot/initrd.img-4.15.0-96-generic
drwxr-xr-x  21 root root 4.0K Oct 20  2018 lib
drwxr-xr-x   2 root root 4.0K Oct 20  2018 lib32
drwxr-xr-x   2 root root 4.0K Jul 25  2018 lib64
drwx------   2 root root  16K Oct 11  2018 lost+found
drwxr-xr-x   4 root root 4.0K Oct 15  2018 media
drwxr-xr-x   3 root root 4.0K Jun 20  2019 mnt
drwxrwxrwx  23 root root 4.0K May  1 16:56 opt
dr-xr-xr-x 302 root root    0 Apr 23 19:57 proc
drwx------   6 root root 4.0K Apr 29 22:31 root
drwxr-xr-x  40 root root 1.4K May  1 14:44 run
drwxr-xr-x   2 root root  12K Feb  9 12:00 sbin
drwxr-xr-x  15 root root 4.0K Apr 25 11:15 snap
drwxr-xr-x   2 root root 4.0K Jul 25  2018 srv
dr-xr-xr-x  13 root root    0 May  1 18:53 sys
drwxrwxrwt  32 root root 4.0K May  1 19:39 tmp
drwxr-xr-x  11 root root 4.0K Oct 20  2018 usr
drwxr-xr-x  15 root root 4.0K Jun 20  2019 var
lrwxrwxrwx   1 root root   30 Apr 30 06:55 vmlinuz -> boot/vmlinuz-4.15.0-99-generic
lrwxrwxrwx   1 root root   30 Apr 30 06:55 vmlinuz.old -> boot/vmlinuz-4.15.0-96-generic
2020-05-01 19:48:06,357 DEBUG - command "['ls', '-ahl', '/']" finished successfully
2020-05-01 19:48:06,357 INFO - stopping application