config('value') is not working on cron(laravel scheduler)

• Laravel Version: 5.3.22
• PHP Version: 7.0.11
• OS: ubuntu 14.04.4

Description:

I was trying to send an email from a job. It was actually calls an external API and I store the URL in config/services.php file like this-

<?php

return [

    'mailgun' => [
        'domain' => env('MAILGUN_DOMAIN'),
        'secret' => env('MAILGUN_SECRET'),
    ],

    'ses' => [
        'key' => env('SES_KEY'),
        'secret' => env('SES_SECRET'),
        'region' => 'us-east-1',
    ],

    'sparkpost' => [
        'secret' => env('SPARKPOST_SECRET'),
    ],

    'stripe' => [
        'model' => App\User::class,
        'key' => env('STRIPE_KEY'),
        'secret' => env('STRIPE_SECRET'),
    ],

    'sm_api' => env('SM_API', 'api-url'),

];

I also use this sm_api value from frontend like this config('services.sm_api'). There it works like a charm. but when I try to use the same value from a laravel job class, which actually dispatched from Redis queue server, the same function call returns null. I tried to log the whole config()->all() and it returns the predefined values, except sm_api.

array (
    'mailgun' => array (
        'domain' => NULL,
        'secret' => NULL,
    ),
    'ses' => array (
        'key' => NULL,
        'secret' => NULL,
        'region' => 'us-east-1',
    ),
    'sparkpost' => array (
        'secret' => NULL,
    ),
    'stripe' => array (
        'model' => 'App\\User',
        'key' => NULL,
        'secret' => NULL,
    ),
)

It also shows mailgun's domain and secret value to null though I set it in the .env file. I also log the env('SM_API') value, and it works from the same job. So, the problem is I can bear with env('SM_API') from the job, but I can use mail, as the mailgun driver and key is null. But all this works fine from the frontend. I also tried it in php artisan tinker, and it works perfectly.

I searched on google for this and found this. This issue suggest to use php artisan config:cache to resolve this. I tried this as well. But nothing happens.

I also posted an issue on laravel/framework repo. If you are interested, then you can look into it here.