Custom logging in Laravel: one dir per month, one file per day

custom_logging.php

<?php

// logs in one dir per month, one file per day
// storage/logs/YYYY-MM/YYYY-MM-DD.log

// paste in bootstrap/app.php, after $app assignation
// reference: https://laravel.com/docs/5.4/errors#custom-monolog-configuration

$app->configureMonologUsing(function () {

    $dir = storage_path('logs/'.date('Y-m'));
    is_dir($dir) || mkdir($dir, 0777, true); // if possible, use stricter permissions e.g. 0755

    $file = $dir.'/'.date('Y-m-d').'.log';
    $level = config('app.log_level', 'debug');

    logger()->useFiles($file, $level);
});