在Python中压缩旧日志文件

Question

我在用Python的标准日志库。里面有一个叫RotatingFileHandler的功能，可以每天自动更换日志文件。

不过，它只是把文件重命名而已。如果能在重命名的同时，把旧的日志文件放进zip（或者gz、bzip等）压缩包里，那就太好了。

有没有简单的方法可以做到这一点呢？

Answer 1

你可以通过初始化 RotatingFileHandler 来自动生成 bz2 压缩的日志文件，方法是设置 encoding='bz2-codec'：

import logging
import logging.handlers as handlers

if __name__=='__main__':
    log_filename='log_rotate.bz2'
    logger = logging.getLogger(__name__)
    logger.setLevel(logging.DEBUG)
    handler = handlers.RotatingFileHandler(
        log_filename, maxBytes=20, backupCount=5, encoding='bz2-codec')
    logger.addHandler(handler)
    for i in range(20):
        logger.debug('i = %d' % i)

另外，Python3 把 'bz2-codec' 从有效编码的列表中去掉了，所以这个方法只适用于 Python2。

Answer 2

被接受的答案只会归档一个文件——basefile.log.1。其他的文件不会被归档。这个代码会把除了基础文件以外的所有日志文件都归档。

import os
import gzip
import logging.handlers

class NewRotatingFileHandler(logging.handlers.RotatingFileHandler):
    def __init__(self, filename, **kws):
        backupCount = kws.get('backupCount', 0)
        self.backup_count = backupCount
        logging.handlers.RotatingFileHandler.__init__(self, filename, **kws)

    def doArchive(self, old_log):
        with open(old_log) as log:
            with gzip.open(old_log + '.gz', 'wb') as comp_log:
                comp_log.writelines(log)
       os.remove(old_log)

   def doRollover(self):
      if self.stream:
          self.stream.close()
          self.stream = None
      if self.backup_count > 0:
          for i in range(self.backup_count - 1, 0, -1):
              sfn = "%s.%d.gz" % (self.baseFilename, i)
              dfn = "%s.%d.gz" % (self.baseFilename, i + 1)
              if os.path.exists(sfn):
                  if os.path.exists(dfn):
                      os.remove(dfn)
                  os.rename(sfn, dfn)
      dfn = self.baseFilename + ".1"
      if os.path.exists(dfn):
          os.remove(dfn)
      if os.path.exists(self.baseFilename):
          os.rename(self.baseFilename, dfn)
          self.doArchive(dfn)
      if not self.delay:
          self.stream = self._open()

Answer 3

我觉得你最好的选择是扩展一下 RotatingFileHandler，可以像这样做（没有测试过）：

import os
from logging.handlers import RotatingFileHandler


COMPRESSION_SUPPORTED = {}

try:
   import gzip
   COMPRESSION_SUPPORTED['gz'] = gzip
except ImportError:
   pass

try:
   import zipfile
   COMPRESSION_SUPPORTED['zip'] = zipfile
except ImportError:
   pass


class NewRotatingFileHandler(RotatingFileHandler):

     def __init__(self, *args, **kws):
         compress_mode = kws.pop('compress_mode')

         try:
             self.compress_cls = COMPRESSION_SUPPORTED[compress_mode]
         except KeyError:
             raise ValueError('"%s" compression method not supported.' % compress_mode)

         super(NewRotatingFileHandler, self).__init__(self, *args, **kws)

     def doRollover(self):
         super(NewRotatingFileHandler, self).doRollover()

         # Compress the old log.
         old_log = self.baseFilename + ".1"
         with open(old_log) as log:
             with self.compress_cls.open(old_log + '.gz', 'wb') as comp_log:
                 comp_log.writelines(log)

         os.remove(old_log)