如何在python日志记录中过滤标准输出

Question

我正在使用库“日志记录”在我的脚本中记录信息和警告消息，无论如何我可以在打印到标准输出时过滤掉密码（我有多个密码并希望用星号替换它们）？

Answer 1

为了过滤掉包含特定的词从你的密码列表stdout流（这就是logging.DEBUG和logging.INFO消息都）和stderr流（这其中logging.WARNING，logging.ERROR和logging.CRITICAL消息走），你可以用一个简单的类，之前替换关键的词替换原有的流把它们写出来：

class PasswordFilter(object):
    def __init__(self, strings_to_filter, stream):
        self.stream = stream
        self.strings_to_filter = strings_to_filter

    def __getattr__(self, attr_name):
        return getattr(self.stream, attr_name)

    def write(self, data):
        for string in self.strings_to_filter:
            data = re.sub(r'\b{0}\b'.format(string), '*' * len(string), data)
        self.stream.write(data)
        self.stream.flush()

    def flush(self):
        self.stream.flush()

用过滤后的流替换原始流，如下所示：

top_secret_passwords = ['do not tell me', 'I am secret', 'important', 'foo',
                        'foobar']
sys.stdout = PasswordFilter(top_secret_passwords, sys.stdout)
sys.stderr = PasswordFilter(top_secret_passwords, sys.stderr)

现在，设置日志记录并写入一些日志消息：

# set up your logging after activating the filter, won't work otherwise
logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger(__name__)

logger.debug('You cannot see me anymore: {0}'.format(top_secret_passwords[0]))
logger.info('You cannot see me anymore: {0}'.format(top_secret_passwords[1]))
logger.warning('You cannot see me anymore: {0}'.format(top_secret_passwords[2]))
logger.error('You cannot see me anymore: {0}'.format(top_secret_passwords[3]))
logger.critical('You cannot see me anymore: {0}'.format(top_secret_passwords[4]))

输出将如下所示：

DEBUG:__main__:You cannot see me anymore: **************
INFO:__main__:You cannot see me anymore: ***********
WARNING:__main__:You cannot see me anymore: *********
ERROR:__main__:You cannot see me anymore: ***
CRITICAL:__main__:You cannot see me anymore: ******