I am learning to utilize logging rather than print to debug my code:
In [89]: logging.basicConfig(level=logging.DEBUG, format=" %(asctime)s - %(levelname)s - %(message)s")
In [90]: logging.debug("Some debugging details.")
2018-08-28 16:41:15,371 - DEBUG - Some debugging details.
I tried to rewrite the format as literal format,
In [5]: logging.basicConfig(level=logging.DEBUG, format=f" {(asctime)} - {(levelname)} - {(message)}")
NameError: name 'asctime' is not defined
or
In [5]: logging.basicConfig(level=logging.DEBUG, format=f" {(asctime)} - {(levelname)} - {(message)}")
-------------------------------------------------------------------------
In [6]: logging.basicConfig(level=logging.DEBUG, format=f" {(asctime)s} - {(levelname)s} - {(message)s}")
File "<fstring>", line 1
((asctime)s)
^
SyntaxError: invalid syntax
Is it possible to write a literal format of format=" %(asctime)s - %(levelname)s - %(message)s"?
No it isn't possible because the placeholder names in the logging format are interpreted by the logging module, while the expressions in the f-string are interpreted by the Python compiler itself, which is unaware of the meaning of the placeholder names understood only by the logging module.
Edit :
Using Liclipse 1.2.1 instead of 1.3.0 or 1.4.0 is working fine. Changelog indicate both Pydev 3.9.1 and Eclipse 4.4.1 updates for 1.3.0. Seems to break logging debug.
Using Liclipse and Pydev debugger (and CPython) with the following code sample, getting that error :
logging.config.dictConfig(config)
File "C:\Python27\lib\logging\config.py", line 794, in dictConfig
dictConfigClass(config).configure()
File "C:\Python27\lib\logging\config.py", line 576, in configure
'%r: %s' % (name, e))
ValueError: Unable to configure handler 'console': 'DictConfigurator' object has no attribute 'startswith'
There is no problem without debugging, is the logging module require run environment and will only work on it ?
Here is the code sample used :
import logging.config
import yaml
def setup_logging():
default_path = 'logger.conf'
default_level = logging.DEBUG
if os.path.exists(default_path):
with open(default_path, 'rt') as f:
config = yaml.load(f.read())
logging.config.dictConfig(config)
else:
logging.basicConfig(level=default_level)
And here is my logger.conf :
version: 1
disable_existing_loggers: False
formatters:
simple:
format: "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
lineInfo:
format: "%(asctime)s - Line: %(lineno)d - %(name)s - %(levelname)s - %(message)s"
handlers:
console:
class: logging.StreamHandler
level: DEBUG
formatter: lineInfo
stream: ext://sys.stdout
debug_file_handler:
class: logging.handlers.RotatingFileHandler
level: DEBUG
formatter: lineInfo
filename: logs/debug.log
maxBytes: 10485760 # 10MB
backupCount: 10
encoding: utf8
info_file_handler:
class: logging.handlers.RotatingFileHandler
level: INFO
formatter: simple
filename: logs/info.log
maxBytes: 10485760 # 10MB
backupCount: 10
encoding: utf8
error_file_handler:
class: logging.handlers.RotatingFileHandler
level: ERROR
formatter: simple
filename: logs/errors.log
maxBytes: 10485760 # 10MB
backupCount: 10
encoding: utf8
root:
level: DEBUG
handlers: [console, info_file_handler, error_file_handler, debug_file_handler]
Thanks
There is now a relatively obscure (because they don't include the OP's error string in their webpage for good search indexing) fix implemented in PyCharm for this:
https://www.jetbrains.com/pycharm/help/python-debugger.html
In PyCharm, go to:
File | Settings | Build, Execution, Deployment | Python Debugger
Then uncheck 'PyQt compatible'
same problem with PyCharm.
possible workaround - to comment out pydev_monkey_qt.patch_qt() line in pycharm/helpers/pydev/pydevd.py, for Eclipse it should be located somewhere else
Ensure to import PyQt4 before importing logging
I need to read follow yaml-formatted configuration file:
version: 1
disable_existing_loggers: False
formatters:
precise:
format: "%(name)-15s # %(levelname)-8s # %(asctime)s # [Line: %(lineno)-3d]: %(message)s"
datefmt: "%Y-%m-%d %H:%M:%S"
handlers:
file:
class: logging.handlers.RotatingFileHandler
filename: <%= ENV['ENV_PROJECT'] %>/target/tracing.log
encoding: utf-8
maxBytes : 10737418244
backupCount: 7
formatter: precise
loggers:
utility:
handlers: [file]
level: INFO
propagate: True
root:
handlers: [file]
level: INFO
But, instead off <%= ENV['ENV_PROJECT'] %> in the result string I need to get the relevant path, for example.
For the loading this file I use follow code:
from yaml import load
with open('test.yml', 'rt') as stream:
configuration = load(stream)
How can I get the required result?
Tnx.
You need to use 'resolver' and 'constructor' to achieve this. Here is one way to achieve this.
import yaml, os, re
#define the regex pattern that the parser will use to 'implicitely' tag your node
pattern = re.compile( r'^\<%= ENV\[\'(.*)\'\] %\>(.*)$' )
#now define a custom tag ( say pathex ) and associate the regex pattern we defined
yaml.add_implicit_resolver ( "!pathex", pattern )
#at this point the parser will associate '!pathex' tag whenever the node matches the pattern
#you need to now define a constructor that the parser will invoke
#you can do whatever you want with the node value
def pathex_constructor(loader,node):
value = loader.construct_scalar(node)
envVar, remainingPath = pattern.match(value).groups()
return os.environ[envVar] + remainingPath
#'register' the constructor so that the parser will invoke 'pathex_constructor' for each node '!pathex'
yaml.add_constructor('!pathex', pathex_constructor)
#that is it
data = """
version: 1
disable_existing_loggers: False
formatters:
precise:
format: "%(name)-15s # %(levelname)-8s # %(asctime)s # [Line: %(lineno)-3d]: %(message)s"
datefmt: "%Y-%m-%d %H:%M:%S"
handlers:
file:
class: logging.handlers.RotatingFileHandler
filename: <%= ENV['ENV_PROJECT'] %>/target/tracing.log
encoding: utf-8
maxBytes : 10737418244
backupCount: 7
formatter: precise
loggers:
utility:
handlers: [file]
level: INFO
propagate: True
root:
handlers: [file]
level: INFO
"""
deSerializedData = yaml.load(data)
print(deSerializedData [ 'handlers'] [ 'file' ] ['filename'] )
I have multiple Python modules, each of which has separate log config files. I am using Yaml, so I just do a
log_config_dict=yaml.load(open(config_file1, 'r'))
logging.config.dictConfig(log_config_dict)
self.main_logger=logging.getLogger('Main_Logger')
In another module, I have something like
log_config_dict=yaml.load(open(config_file2, 'r'))
logging.config.dictConfig(log_config_dict)
self.main_logger=logging.getLogger('Poller_Main_Logger')
The 2 loggers are writing to separate log files. Then in the code for each separate module, I do logging as -
self.main_logger.info(log_str)
However this is not working as expected. Say I do logging from module1,then from module2, then from module1 again, the log messages are either written to module2's destination, or not written at all.
Any idea what is happening? Is the problem that each time I do a dictConfig call, previous loggers are disabled? Is there any way around this?
Below - one of the log config files
version: 1
formatters:
default_formatter:
format: '%(asctime)s : %(levelname)s : %(message)s'
datefmt: '%d-%b-%Y %H:%M:%S'
plain_formatter:
format: '%(message)s'
handlers:
console_default_handler:
class: logging.StreamHandler
level: INFO
formatter: default_formatter
stream: ext://sys.stdout
console_error_handler:
class: logging.StreamHandler
level: WARNING
formatter: default_formatter
stream: ext://sys.stderr
logfile_handler:
class: logging.FileHandler
filename: logger.txt
mode: a
formatter: default_formatter
level: DEBUG
errfile_handler:
class: logging.FileHandler
filename: error.txt
mode: a
formatter: default_formatter
level: WARNING
plain_handler:
class: logging.StreamHandler
level: DEBUG
formatter: plain_formatter
stream: ext://sys.stdout
loggers:
Poller_Main_Logger:
level: DEBUG
handlers: [console_default_handler,logfile_handler]
propagate: no
Plain_Logger:
level: DEBUG
handlers: [plain_handler]
propagate: no
Error_Logger:
level: WARNING
handlers: [errfile_handler,console_error_handler,logfile_handler]
propagate: no
root:
level: INFO
handlers: [console_default_handler]
logging doesn't support the usage pattern you want here. By default, rerunning logging.config.dictConfig() blows away all existing loggers, handlers, and formatters. There are the incremental and disable_existing_loggers options available for use in the config dict, but using incremental, you can't load in new handlers or formatters. You either need to combine you configuration in to a single file for your whole program, or use the mechanisms provided in the module to manually construct and add formatters and handlers to loggers.
How can I use the logging module in Python to write to a file? Every time I try to use it, it just prints out the message.
An example of using logging.basicConfig rather than logging.fileHandler()
logging.basicConfig(filename=logname,
filemode='a',
format='%(asctime)s,%(msecs)d %(name)s %(levelname)s %(message)s',
datefmt='%H:%M:%S',
level=logging.DEBUG)
logging.info("Running Urban Planning")
logger = logging.getLogger('urbanGUI')
In order, the five parts do the following:
set the output file (filename=logname)
set it to append rather than overwrite (filemode='a')
determine the format of the output message (format=...)
determine the format of the output time (datefmt='%H:%M:%S')
and determine the minimum message level it will accept (level=logging.DEBUG).
Taken from the "logging cookbook":
# create logger with 'spam_application'
logger = logging.getLogger('spam_application')
logger.setLevel(logging.DEBUG)
# create file handler which logs even debug messages
fh = logging.FileHandler('spam.log')
fh.setLevel(logging.DEBUG)
logger.addHandler(fh)
And you're good to go.
P.S. Make sure to read the logging HOWTO as well.
Here is two examples, one print the logs (stdout) the other write the logs to a file:
import logging
import sys
logger = logging.getLogger()
logger.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s | %(levelname)s | %(message)s')
stdout_handler = logging.StreamHandler(sys.stdout)
stdout_handler.setLevel(logging.DEBUG)
stdout_handler.setFormatter(formatter)
file_handler = logging.FileHandler('logs.log')
file_handler.setLevel(logging.DEBUG)
file_handler.setFormatter(formatter)
logger.addHandler(file_handler)
logger.addHandler(stdout_handler)
With this example, all logs will be printed and also be written to a file named logs.log
Use example:
logger.info('This is a log message!')
logger.error('This is an error message.')
List of all built-in logging handlers https://docs.python.org/3/library/logging.handlers.html
I prefer to use a configuration file. It allows me to switch logging levels, locations, etc without changing code when I go from development to release. I simply package a different config file with the same name, and with the same defined loggers.
import logging.config
if __name__ == '__main__':
# Configure the logger
# loggerConfigFileName: The name and path of your configuration file
logging.config.fileConfig(path.normpath(loggerConfigFileName))
# Create the logger
# Admin_Client: The name of a logger defined in the config file
mylogger = logging.getLogger('Admin_Client')
msg='Bite Me'
myLogger.debug(msg)
myLogger.info(msg)
myLogger.warn(msg)
myLogger.error(msg)
myLogger.critical(msg)
# Shut down the logger
logging.shutdown()
Here is my code for the log config file
#These are the loggers that are available from the code
#Each logger requires a handler, but can have more than one
[loggers]
keys=root,Admin_Client
#Each handler requires a single formatter
[handlers]
keys=fileHandler, consoleHandler
[formatters]
keys=logFormatter, consoleFormatter
[logger_root]
level=DEBUG
handlers=fileHandler
[logger_Admin_Client]
level=DEBUG
handlers=fileHandler, consoleHandler
qualname=Admin_Client
#propagate=0 Does not pass messages to ancestor loggers(root)
propagate=0
# Do not use a console logger when running scripts from a bat file without a console
# because it hangs!
[handler_consoleHandler]
class=StreamHandler
level=DEBUG
formatter=consoleFormatter
args=(sys.stdout,)# The comma is correct, because the parser is looking for args
[handler_fileHandler]
class=FileHandler
level=DEBUG
formatter=logFormatter
# This causes a new file to be created for each script
# Change time.strftime("%Y%m%d%H%M%S") to time.strftime("%Y%m%d")
# And only one log per day will be created. All messages will be amended to it.
args=("D:\\Logs\\PyLogs\\" + time.strftime("%Y%m%d%H%M%S")+'.log', 'a')
[formatter_logFormatter]
#name is the name of the logger root or Admin_Client
#levelname is the log message level debug, warn, ect
#lineno is the line number from where the call to log is made
#04d is simple formatting to ensure there are four numeric places with leading zeros
#4s would work as well, but would simply pad the string with leading spaces, right justify
#-4s would work as well, but would simply pad the string with trailing spaces, left justify
#filename is the file name from where the call to log is made
#funcName is the method name from where the call to log is made
#format=%(asctime)s | %(lineno)d | %(message)s
#format=%(asctime)s | %(name)s | %(levelname)s | %(message)s
#format=%(asctime)s | %(name)s | %(module)s-%(lineno) | %(levelname)s | %(message)s
#format=%(asctime)s | %(name)s | %(module)s-%(lineno)04d | %(levelname)s | %(message)s
#format=%(asctime)s | %(name)s | %(module)s-%(lineno)4s | %(levelname)-8s | %(message)s
format=%(asctime)s | %(levelname)-8s | %(lineno)04d | %(message)s
#Use a separate formatter for the console if you want
[formatter_consoleFormatter]
format=%(asctime)s | %(levelname)-8s | %(filename)s-%(funcName)s-%(lineno)04d | %(message)s
http://docs.python.org/library/logging.html#logging.basicConfig
logging.basicConfig(filename='/path/to/your/log', level=....)
here's a simpler way to go about it. this solution doesn't use a
config dictionary and uses a rotation file handler, like so:
import logging
from logging.handlers import RotatingFileHandler
logging.basicConfig(handlers=[RotatingFileHandler(filename=logpath+filename,
mode='w', maxBytes=512000, backupCount=4)], level=debug_level,
format='%(levelname)s %(asctime)s %(message)s',
datefmt='%m/%d/%Y%I:%M:%S %p')
logger = logging.getLogger('my_logger')
or like so:
import logging
from logging.handlers import RotatingFileHandler
handlers = [ RotatingFileHandler(filename=logpath+filename,
mode='w',
maxBytes=512000,
backupCount=4)
]
logging.basicConfig(handlers=handlers,
level=debug_level,
format='%(levelname)s %(asctime)s %(message)s',
datefmt='%m/%d/%Y%I:%M:%S %p')
logger = logging.getLogger('my_logger')
the handlers variable needs to be an iterable. logpath+filename and debug_level are just variables holding the
respective info. of course, the values for the function params are up
to you.
the first time i was using the logging module i made the mistake of writing the following, which generates an OS file lock error (the
above is the solution to that):
import logging
from logging.handlers import RotatingFileHandler
logging.basicConfig(filename=logpath+filename,
level=debug_level,
format='%(levelname)s %(asctime)s %(message)s',
datefmt='%m/%d/%Y%I:%M:%S %p')
logger = logging.getLogger('my_logger')
logger.addHandler(RotatingFileHandler(
filename=logpath+filename,
mode='w',
maxBytes=512000,
backupCount=4))
http://docs.python.org/library/logging.handlers.html#filehandler
The FileHandler class, located in the core logging package, sends logging output to a disk file.
This example should work fine. I have added streamhandler for console. Console
log and file handler data should be similar.
# MUTHUKUMAR_TIME_DATE.py #>>>>>>>> file name(module)
import sys
import logging
import logging.config
# ================== Logger ================================
def Logger(file_name):
formatter = logging.Formatter(fmt='%(asctime)s %(module)s,line: %(lineno)d %(levelname)8s | %(message)s',
datefmt='%Y/%m/%d %H:%M:%S') # %I:%M:%S %p AM|PM format
logging.basicConfig(filename = '%s.log' %(file_name),format= '%(asctime)s %(module)s,line: %(lineno)d %(levelname)8s | %(message)s',
datefmt='%Y/%m/%d %H:%M:%S', filemode = 'w', level = logging.INFO)
log_obj = logging.getLogger()
log_obj.setLevel(logging.DEBUG)
# log_obj = logging.getLogger().addHandler(logging.StreamHandler())
# console printer
screen_handler = logging.StreamHandler(stream=sys.stdout) #stream=sys.stdout is similar to normal print
screen_handler.setFormatter(formatter)
logging.getLogger().addHandler(screen_handler)
log_obj.info("Logger object created successfully..")
return log_obj
# =======================================================
MUTHUKUMAR_LOGGING_CHECK.py #>>>>>>>>>>> file name
# calling **Logger** function
file_name = 'muthu'
log_obj =Logger(file_name)
log_obj.info("yes hfghghg ghgfh".format())
log_obj.critical("CRIC".format())
log_obj.error("ERR".format())
log_obj.warning("WARN".format())
log_obj.debug("debug".format())
log_obj.info("qwerty".format())
log_obj.info("asdfghjkl".format())
log_obj.info("zxcvbnm".format())
# closing file
log_obj.handlers.clear()
OUTPUT:
2019/07/13 23:54:40 MUTHUKUMAR_TIME_DATE,line: 17 INFO | Logger object created successfully..
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 8 INFO | yes hfghghg ghgfh
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 9 CRITICAL | CRIC
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 10 ERROR | ERR
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 11 WARNING | WARN
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 12 DEBUG | debug
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 13 INFO | qwerty
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 14 INFO | asdfghjkl
2019/07/13 23:54:40 MUTHUKUMAR_LOGGING_CHECK,line: 15 INFO | zxcvbnm
Thanks,
import logging
from datetime import datetime
filename = datetime.now().strftime("%d-%m-%Y %H-%M-%S")#Setting the filename from current date and time
logging.basicConfig(filename=filename, filemode='a',
format="%(asctime)s, %(msecs)d %(name)s %(levelname)s [ %(filename)s-%(module)s-%(lineno)d ] : %(message)s",
datefmt="%H:%M:%S",
level=logging.DEBUG)
asctime
%(asctime)s
Human-readable time when the LogRecord was created. By default this
is of the form ‘2003-07-08 16:49:45,896’ (the numbers after the comma
are millisecond portion of the time).
created
%(created)f
Time when the LogRecord was created (as returned by time.time()).
exc_info
You shouldn’t need to format this yourself.
Exception tuple (à la sys.exc_info) or, if no exception has occurred,
None.
filename
%(filename)s
Filename portion of pathname.
funcName
%(funcName)s
Name of function containing the logging call.
levelname
%(levelname)s
Text logging level for the message ('DEBUG', 'INFO', 'WARNING',
'ERROR', 'CRITICAL').
levelno
%(levelno)s
Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR,
CRITICAL).
lineno
%(lineno)d
Source line number where the logging call was issued (if available).
message
%(message)s
The logged message, computed as msg % args. This is set when
Formatter.format() is invoked.
module
%(module)s
Module (name portion of filename).
msecs
%(msecs)d
Millisecond portion of the time when the LogRecord was created.
msg
You shouldn’t need to format this yourself.
The format string passed in the original logging call. Merged with
args to produce message, or an arbitrary object (see Using arbitrary
objects as messages).
name
%(name)s
Name of the logger used to log the call.
pathname
%(pathname)s
Full pathname of the source file where the logging call was issued
(if available).
process
%(process)d
Process ID (if available).
processName
%(processName)s
Process name (if available).
relativeCreated
%(relativeCreated)d
Time in milliseconds when the LogRecord was created, relative to the
time the logging module was loaded.
stack_info
You shouldn’t need to format this yourself.
Stack frame information (where available) from the bottom of the
stack in the current thread, up to and including the stack frame of
the logging call which resulted in the creation of this record.
thread
%(thread)d
Thread ID (if available).
threadName
%(threadName)s
Thread name (if available).
Head over to official python3 page for more info regarding logging.
Although it is an old question, for people reaching this question these days, you can also use dictConfig. For example, for a file with info level and above :
logging.config.dictConfig({
'version': 1,
'formatters': {
'default': {
'format': '[%(asctime)s] %(message)s',
}
},
'handlers': {
'info': {
'level': logging.INFO,
'class': 'logging.FileHandler',
'filename': 'info.log',
},
},
"root": {
"level": logging.INFO,
"handlers": ["info"]
}
})
Or another example to be more specific, with rotating file and in a specific directory :
today = datetime.date.today()
folder = './log'
Path(folder).mkdir(parents=True, exist_ok=False) # Create folder if not exists
logging.config.dictConfig({
...
'info': {
'level': logging.INFO,
'class': 'logging.handlers.TimedRotatingFileHandler',
'filename': f'{folder}/info-{today.month:02}-{today.year}.log',
# Roll over on the first day of the weekday
'when': 'W0',
# Roll over at midnight
'atTime': datetime.time(hour=0),
# Number of files to keep.
'backupCount': 8
},
...
import sys
import logging
from util import reducer_logfile
logging.basicConfig(filename=reducer_logfile, format='%(message)s',
level=logging.INFO, filemode='w')
best and clean method.
ds = datetime.now().strftime("%Y%m%d_%H%M%S")
try:
# py39 有force参数指定可能强制除去之前的handler，这里使用兼容写法，0708
logging.getLogger().removeHandler(logging.getLogger().handlers[0])
logging.getLogger().removeHandler(logging.getLogger().handlers[0])
except:
pass
logging.basicConfig(
# force=
level=logging.INFO,
format="%(asctime)s [%(levelname)s] %(message)s",
handlers=[
logging.FileHandler('log_%s_%s_%s.log' % (ds, create_net, os.path.basename(dataset_path))),
logging.StreamHandler(sys.stdout)
]
)
logging.info('start train')