logging module Basics
- Simple printing of logs to screen
import logging logging.debug('This is debug message') logging.info('This is info message') logging.warning('This is warning message') //Screen Printing: WARNING:root:This is warning message
By default, logging prints the log to the screen with a log level of WARNING: the log level size relationship is CARITICAL > ERROR > WARNING > INFO > DEBUG > NOTEST, or you can define the log level yourself.
- Configure the output format and mode of logs through logging.basicConfig function
import logging logging.basicConfig(level = logging.DEBUG, format = '%(asctime)s %(filename)s[line:%(lineo)d] %(levelname)s %(message)s', datefmt = '%a,%d %b %Y %H:%M:%S', filename = 'myapp.log', filemode = 'w') logging.debug('This is debug message') logging.info('This is info message') logging.warning('This is warning message') ./myapp.log The contents of the file are: Sun, 24 May 2009 21:48:54 demo2.py[line:11] DEBUG This is debug message Sun, 24 May 2009 21:48:54 demo2.py[line:12] INFO This is info message Sun, 24 May 2009 21:48:54 demo2.py[line:13] WARNING This is warning message
Parameters of logging.basicConfig function
| Parameter Name | Parameter Meaning |
|---|---|
| filename | Specify log file name |
| filemode | Same as the file function, specify how the log file will be opened'w'or'a' |
| format | Specify the format and content of the output, which can output a lot of useful information |
| %(levelno)s | Print log level values |
| %(levelname)s | Print log level values |
| %(pathname)s | Print the path to the current executor, which is sys.argv[0] |
| %(filename)s | Print the name of the currently executing program |
| %(funcName)s | Current function for printing logs |
| %(lineno)d | Print the current line number of the log |
| %(asctime)s | Current time for printing logs |
| %(thread)d | Print Thread ID |
| %(threadName)s | Print Thread Name |
| %(process)d | Print process ID |
| %(message)s | Print log information |
| datefmt | Specify the time format, the same as time.strftime() |
| level | Set the log level, defaulting to logging.WARNING |
| stream | Specifies the output stream to log, can specify output to sys.stderr,sys.stdout, or file, default output to sys.stderr, stream is ignored when both stream and filename are specified |
Several handle s for logging are as follows
| Function Name | Functional action |
|---|---|
| logging.StreamHandler | Log output to stream, can be sys.stderr, sys.stdout, or file |
| logging.FileHandler | Log output to file |
| logging.handlers.BaseRotatingHandler | |
| logging.handlers.RotatingFileHandler | |
| logging.handlers.TimedRotatingFileHandler | |
| logging.handlers.SocketHandler | Remote output log to TCP/IP sockets |
| logging.handlers.DatagramHandler | Remote output log to UDP sockets |
| logging.handlers.SMTPHandler | Remote Output Log to Mail Address |
| logging.handlers.SysLogHandler | Log output to syslog |
| logging.handlers.NTEventLogHandler | Remote Output Log to Event Log for Windows NT/2000/XP |
| logging.handlers.MemoryHandler | Make buffer for log output to memory |
| logging.handlers.HTTPHandler | Remote Output to HTTP Server via GET or POST |
Because StreamHandler and FileHandler are common ways of handling logs, they are included directly in the logging module, while others are included in the logging.handlers module
logging module instance
- Output log to both file and screen
import logging logging.basicConfig(level=logging.DEBUG, format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s', datefmt='%a, %d %b %Y %H:%M:%S', filename='myapp.log', filemode='w') ################################################################################################# #Define a StreamHandler，take INFO Level or higher log information is printed to standard errors and added to the current log processing object# console = logging.StreamHandler() console.setLevel(logging.INFO) formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s') console.setFormatter(formatter) logging.getLogger('').addHandler(console) ################################################################################################# logging.debug('This is debug message') logging.info('This is info message') logging.warning('This is warning message') //On-screen printing: root : INFO This is info message root : WARNING This is warning message ./myapp.log The contents of the file are: Sun, 24 May 2009 21:48:54 demo2.py[line:11] DEBUG This is debug message Sun, 24 May 2009 21:48:54 demo2.py[line:12] INFO This is info message Sun, 24 May 2009 21:48:54 demo2.py[line:13] WARNING This is warning message
- logging Log Rollback
import logging from logging.handlers import RotatingFileHandler #Define a Rotating FileHandler that backs up up up up to five log files, up to 10M per log file Rthandler = RotatingFileHandler('myapp.log', maxBytes=10*1024*1024,backupCount=5) Rthandler.setLevel(logging.INFO) formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s') Rthandler.setFormatter(formatter) logging.getLogger('').addHandler(Rthandler)
As you can see from the above example and this example, logging has a primary object for log processing, and all other processing is added through addHandler
- Configuring logs through logging.config module
#logger.conf ############################################### [loggers] keys=root,example01,example02 [logger_root] level=DEBUG handlers=hand01,hand02 [logger_example01] handlers=hand01,hand02 qualname=example01 propagate=0 [logger_example02] handlers=hand01,hand03 qualname=example02 propagate=0 ############################################### [handlers] keys=hand01,hand02,hand03 [handler_hand01] class=StreamHandler level=INFO formatter=form02 args=(sys.stderr,) [handler_hand02] class=FileHandler level=DEBUG formatter=form01 args=('myapp.log', 'a') [handler_hand03] class=handlers.RotatingFileHandler level=INFO formatter=form02 args=('myapp.log', 'a', 10*1024*1024, 5) ############################################### [formatters] keys=form01,form02 [formatter_form01] format=%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s datefmt=%a, %d %b %Y %H:%M:%S [formatter_form02] format=%(name)-12s: %(levelname)-8s %(message)s datefmt=
- Example 1:
import logging import logging.config logging.config.fileConfig("logger.conf") logger = logging.getLogger("example01") logger.debug('This is debug message') logger.info('This is info message') logger.warning('This is warning message')
- Example 2:
import logging import logging.config logging.config.fileConfig("logger.conf") logger = logging.getLogger("example02") logger.debug('This is debug message') logger.info('This is info message') logger.warning('This is warning message')