View file vendor/laravel/framework/src/Illuminate/Log/LogServiceProvider.php

<?php

namespace Illuminate\Log;

use Illuminate\Support\ServiceProvider;

class LogServiceProvider extends ServiceProvider
{
    /**
     * Register the service provider.
     *
     * @return void
     */
    public function register()
    {
        $this->app->singleton('log', function ($app) {
            return new LogManager($app);
        });
    }
}