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Month: March 2020

Loguru, ftw

March 31, 2020 /

In virtually all the applications and operations I write, I try to incorporate some level of logging so that my code can be adequately supported, particularly in Production environments. Some time ago, I wrote about how I generally log in my Python applications. Well, lately, I’ve switched from that approach to using Loguru and I must say I’m rather satisfied with its ease of use. Here’s a quick example I put together recently of the package:

Step 1: Do your standard imports

As I explained in other posts on logging, I like adding a “run id” to each log line so that I can easily group lines together belonging to a single instance of my application, so I import the uuid package to help in that regard:

import os
import sys
import uuid
from loguru import logger

Step 2: Setup/customize my logging context

In one line, I can customize how each log line is written and set logging behavior like rolling the file when it hits 10 Mb in size:

runid = str(uuid.uuid4()).split('-')[-1]
logger.add('loguru_example.log', format='{time}|{extra[runid]}|{level}|{message}', level='INFO', rotation='10 MB')
logger_ctx = logger.bind(runid=runid)

Step 3: Start logging

def main(argv):
    logger_ctx.info('Starting run of the loguru_example.py script')
    # do some stuff
    logger_ctx.info('Completing run of the loguru_example.py script')


if __name__ == '__main__':
    main(sys.argv[1:])

And now you have a nice and easy log for your application:

Pretty darn simple! So now there’s no excuse: start logging today!

Logging in PowerShell

March 12, 2020 /

As far as I can tell, there are no logging APIs built into the PowerShell framework. So, when I have to write a code solution in PowerShell, I just add this snippet to meet some of my basic logging needs.

Set up some helper variables

I need to set the name and location of my log file. In addition, I like to add a “run id” to my logs so that I can easily group all the log entries associated with a given execution together for analysis or performance reporting:

$ExecutionDir = Split-Path $MyInvocation.MyCommand.Path
$RunId = ([guid]::NewGuid()).ToString().Replace("-", "")
$logFile = "$ExecutionDir\my_log.log"

Add my helper function

This simple helper function meets my basic logging needs:

function Write-Log($logMsg){
    ("{0}|{1}|{2}" -f ("{0:yyyy-MM-dd HH:mm:ss}" -f (Get-Date).ToUniversalTime()), $RunId, $logMsg) | Out-File $logFile -Append
}

Now, log away

Write-Log -logMsg "Starting up some script"
# do some work here
Sleep 2
Write-Log -logMsg "Finishing some script"

This produces a simple log like below. You can see my “run id” in the second column that helps me group log lines together by unique executions:

Sure, there are no log levels, no file rotations, no easy way to change the format…but in lieu of a built in API, this does the trick. One way it could be improved would be to stick this work into a module that I could simply import from script-to-script instead of copy/pasting this code around.

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