Day 56: DIY application log facility in Python

I made my own app logger in Python

app logger

And you can too ! Or you can just use what I already built :)

Here’s how.

Why ?

Python does have a logging for error messages.

But in my case, I needed to log everything, not just errors.

Looked everywhere.

But couldn’t find anything that matched my usecase.

So, I built my own logging facility.

Building it

First, you need to know what you want.

Basically, it’s a logging facility.

  1. Not create clutter, store all the logs in a proper folder.

  2. The name of the log should be chosen by me.

  3. Logs should have a date so that for each date, there is a specific log.

  4. Each action should have a unique timestamp.

Class creation

import os
from datetime import datetime

class Logger:
    __logname = ''
    __folderpath = ''
    __logpath = ''
    __gen_date_v = ''
    __timestamp = ''

Everything I needed is kept as a global variable.


os –> For file saving and creating directory

datetime –> For generating current dates and formatting variables

Class init method

    def __init__(self, logname):
        """ Init for class """
        self.__logname = logname

Here, I am taking logname as an argument (user provided).

__make_folder function

    def __make_folder(self):
        cwd = os.getcwd()
        dirname = self.__logname + "_logs"
        self.__folderpath = os.path.join(cwd, dirname)
            os.makedirs (self.__folderpath,exist_ok = True)
        except OSError:

We get the current working directory and store it to cwd var.

We concatenate the user-provided name with ‘_logs’ for the folder

We join everything together in the full folder path.

Notice the exist_ok parameter, which we prevent any complain if the directory already exists.

__gen_date function

    def __gen_date(self):
        """ To generate date for logfile """
        now =
        format = "%d%m%Y"
        self.__gen_date_v = now.strftime(format)

This justs gives us the current date, stored in the global variable.

__gen_log function

    def __gen_log(self):
        """ Create log with with date and extension """
        logdate = self.__gen_date_v
        logext = ".log"
        current_logname = str(self.__logname) + "_" + str(logdate) + logext
        self.__logpath = os.path.join(self.__folderpath, current_logname)
        if not os.path.exists(self.__logpath):
            f = open (self.__logpath, "w")

This function is where we generate the log file.

We first call gen_date, to refresh current date (in case the program was running on the 24/02 at 23:59 and we suddenly are in the future! (25/02 at 00:00)

We add the extension (.log).

You can change that to anything you want: (.csv, .txt)

If the file exists, we continue without doing anything.

__gen_timestamp function

    def __gen_timestamp(self):
        self.__timestamp =

We simply generate a timestamp for our log.

write function

    def write(self, action='action', data='data'):

        timestamp = str(self.__timestamp)
        data = str(data)
        action = str(action)
        separator = " "
        textual = timestamp + separator + action + separator + data
        f = open (self.__logpath, "a")

Our final function (method), where we create a folder, create a log file and generate a timestamp for each log entry.

Here, I am using a space as a separator, but you may use a semicolumn, in case of a .csv.


Everything is well detailed on the repo that i just created.

And don’t forget to star the repo if it was useful to you :) !

\ Codarren /

Written on February 25, 2021