book_admin/application/extra/gdt.php

<?php
/**
 * Created by: PhpStorm
 * User: lytian
 * Date: 2020/2/27
 * Time: 15:25
 */

return [
    'client_id' => \think\Env::get('gdt.client_id', ''),
    'client_secret' => \think\Env::get('gdt.client_secret', ''),
    'callback_host' => \think\Env::get('gdt.callback_host', ''),
];