Use ngrok URLs in Laravel for all assets, generated URLs, etc.

AppServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\Facades\URL;
use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Str;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }

    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot(\Illuminate\Http\Request $request)
    {
        /**
         * Use ngrok URLs for assets and links
         * 
         * If an ngrok URL is set in the APP_URL environment variable then force HTTPS and
         * replace the HTTP_HOST header with the ngrok URL from HTTP_X_ORIGINAL_HOST
         */
        if (
            $request->server->has('HTTP_X_ORIGINAL_HOST')
            && Str::contains($request->server->get('HTTP_X_ORIGINAL_HOST'), 'ngrok.io')
        ) {
            URL::forceScheme('https');
            $request->server->set('HTTP_HOST', $request->server->get('HTTP_X_ORIGINAL_HOST'));
            $request->headers->set('HOST', $request->server->get('HTTP_X_ORIGINAL_HOST'));
        }
    }
}