https://www.onphpid.com/laravel-5-4-login-facebook-google-github-linkedin-bitbucket-bahasa-indonesia.html

service.php

'github' => [
        'client_id' => env('GITHUB_KEY'),
        'client_secret' => env('GITHUB_SECRET'),
        'redirect' => env('GITHUB_CALLBACK_URL'),
    ],

    'google' => [
        'client_id' => env('GOOGLE_KEY'),
        'client_secret' => env('GOOGLE_SECRET'),
        'redirect' => env('GOOGLE_CALLBACK_URL'),
    ],

    'facebook' => [
        'client_id' => env('FACEBOOK_KEY'),
        'client_secret' => env('FACEBOOK_SECRET'),
        'redirect' => env('FACEBOOK_CALLBACK_URL'),
    ],

    'bitbucket' => [
        'client_id' => env('BITBUCKET_KEY'),
        'client_secret' => env('BITBUCKET_SECRET'),
        'redirect' => env('BITBUCKET_CALLBACK_URL'),
    ],

    'linkedin' => [
        'client_id' => env('LINKEDIN_KEY'),
        'client_secret' => env('LINKEDIN_SECRET'),
        'redirect' => env('LINKEDIN_CALLBACK_URL'),
    ],