Science and technology

Use logzero for easy logging in Python

The logzero library makes logging as straightforward as a print assertion, which is sort of a feat of simplicity. I am unsure whether or not logzero took its title to slot in with the sequence of “zero boilerplate” libraries like pygame-zero, GPIO Zero, and guizero, however it’s definitely in that class. It’s a Python library that makes logging easy.

You can simply use its primary logging to stdout the identical manner you may use print for info and debugging functions, and it has a clean studying curve in direction of extra superior logging, like logging to a file.

To begin, set up logzero with pip:

$ sudo pip3 set up logzero

Now in a Python file, import logger and check out one or all of those logging examples:

from logzero import logger


The output is mechanically coloured in an easy-to-read manner:

So now, as an alternative of utilizing print to determine what is going on on, use logger as an alternative, with the related log degree.

Writing logs to a file in Python

If you solely learn this far and make that one change in the way in which you write code, that is ok for me. If you wish to go additional, learn on!

Writing to stdout is enjoyable for testing a brand new program, however it is just helpful in case you are logged into the pc the place the script is working. Many occasions when utilizing an utility you will wish to execute the code remotely and assessment errors after the actual fact. That’s when it is useful to log to a file as an alternative. Let’s attempt it:

from logzero import logger, logfile


Now your log entries will likely be logged into the file check.log. Remember to make it possible for the script has permission to jot down to that file and its listing construction.

You can specify some extra choices too:

logfile(’/house/pi/check.log, maxBytes=1e6, backupCount=three)

Now when the file supplied to logfile reaches 1MB (1×106 bytes), it’ll rotate entries by means of check.log.1, check.log.2, and so forth. This habits is sweet to keep away from producing a large log file that’s I/O intensive for the system to open and shut. You may additionally wish to log to /var/log like a professional. Assuming you are on Linux, you a listing and make your person the proprietor to allow them to write to it:

$ sudo mkdir /var/log/check
$ sudo chown pi /var/log/check

Then in your Python code, change the logfile path:

logfile(’/var/log/check/check.log, maxBytes=1e6, backupCount=three)

When it involves catching exceptions in your logfile, you’ll be able to both use logging.exception:

    c = a / b
besides Exception as e:

This will produce the next (within the case that b is zero):

[E 190422 23:41:59 check:9] division by zero
     Traceback (most up-to-date name final):
       File "", line 7, in
         c = a / b
     ZeroDivisionError: division by zero

You get the log entry, adopted by the complete traceback. Alternatively, you can use logging.error and conceal the traceback:

    c = a / b
besides Exception as e:
    logger.error(f": e")

Now this can produce the extra succinct:

[E 190423 00:04:16 check:9] ZeroDivisionError: division by zero

There are loads extra choices which you’ll be able to learn within the docs at

logzero shines for training

Logging could be a difficult idea for a brand new programmer. Most frameworks rely upon circulation management and many variable manipulation to make a significant log, however logzero is totally different. With its syntax being much like a print assertion, it’s a large win for training because it saves from explaining one other idea. Give it a attempt in your subsequent challenge.

This article was initially written on my blog and is republished with permission.

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