Print timestamp for logging in Python

Question

I want to print the current timestamp, when an event succeeded or not in my python script. By only adding...

datetime.datetime.now().strftime("%d.%b %Y %H:%M:%S") 

.... at the beginning of each line, te same date appears in every line

[INFO] 04.Feb 2015 20:49:41: cl1 [ OK ] 04.Feb 2015 20:49:41: 8.8.8.8 ONLINE! [INFO] 04.Feb 2015 20:49:41: cl2 [ OK ] 04.Feb 2015 20:49:41: 8.8.8.8 ONLINE! [INFO] 04.Feb 2015 20:49:41: cl3 [ OK ] 04.Feb 2015 20:49:41: 8.8.8.8 ONLINE! 

(I added time.sleep(5)in between)

My next idea was to create a function, calling the current time, but i'm failing at embedding this function to the printcommand.

File rs.py

OK =   "[" + bc.OKGREEN + " OK "  + bc.ENDC + "] " + datetime.datetime.now().strftime("%d.%b %Y %H:%M:%S") INFO = "[" + bc.OKBLUE  + "INFO"  + bc.ENDC + "] " + datetime.datetime.now().strftime("%d.%b %Y %H:%M:%S") WARN = "[" + bc.WARN    + "WARN"  + bc.ENDC + "] " + datetime.datetime.now().strftime("%d.%b %Y %H:%M:%S") ERR =  "[" + bc.ERR     + "FAIL"  + bc.ENDC + "] " + datetime.datetime.now().strftime("%d.%b %Y %H:%M:%S") DEB =  "[" + bc.HEADER  + "DEBUG" + bc.ENDC + "] " + datetime.datetime.now().strftime("%d.%b %Y %H:%M:%S") 

File myapp.py

import rs # importing rs.py  print rs.OK + hostname + "is up!" time.sleep(3) print rs.ERR+ hostname + "is down!" 

Is printing:

>>> [INFO] 04.Feb 2015 20:49:41: xxx is up! >>> [ERR ] 04.Feb 2015 20:49:41: xxx is down! 

Answer 1

Before the first time you log anything do this:

logging.basicConfig(     format='%(asctime)s %(levelname)-8s %(message)s',     level=logging.INFO,     datefmt='%Y-%m-%d %H:%M:%S') 

Example on the REPL:

>>> import logging >>> logging.basicConfig( ...         format='%(asctime)s %(levelname)-8s %(message)s', ...         level=logging.INFO, ...         datefmt='%Y-%m-%d %H:%M:%S') >>>  >>> logging.info('an info messge') 2017-05-25 00:58:28 INFO     an info messge >>> logging.debug('a debug messag is not shown') >>>  

Answer 2

Something like below would do:

formatter = logging.Formatter(fmt='%(asctime)s %(levelname)-8s %(message)s',                               datefmt='%Y-%m-%d %H:%M:%S') 

Have a look at the logging module for Python. You don't need to mess about with creating your own date, just let the logging module do it for you. That formatter object can be applied to a logging handler so you can just log with logger.info('This is an info message.'). No print statements required.

Here's a boilerplate procedure I use:

import logging import sys  def setup_custom_logger(name):     formatter = logging.Formatter(fmt='%(asctime)s %(levelname)-8s %(message)s',                                   datefmt='%Y-%m-%d %H:%M:%S')     handler = logging.FileHandler('log.txt', mode='w')     handler.setFormatter(formatter)     screen_handler = logging.StreamHandler(stream=sys.stdout)     screen_handler.setFormatter(formatter)     logger = logging.getLogger(name)     logger.setLevel(logging.DEBUG)     logger.addHandler(handler)     logger.addHandler(screen_handler)     return logger  >>> logger = setup_custom_logger('myapp') >>> logger.info('This is a message!') 2015-02-04 15:07:12 INFO     This is a message! >>> logger.error('Here is another') 2015-02-04 15:07:30 ERROR    Here is another