Remote server at mydomain.com returned an HTTP 502 when send test in coinbase commerce webhook

i run my laravel app with nginx server on AWS EC2. i make handleWebhook function with post method to receive coinbasecommerce webhook event . this post method is API endpoint url in api.php

Route::post('/webhook/coinbase',[App\Http\Controllers\HomeController::class,'handleWebhook'])->name('charge.webhook');

i set this route as endpoint url in coinbasecommerce notification page.

https://mydomain/api/webhook/coinbase

i also make nginx conf block for proxy pass url for this route

location /api/webhook/coinbase {
  proxy_pass http://localhost:8000;
  proxy_set_header Host $host;
  proxy_set_header X-Real-IP $remote_addr;
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  proxy_set_header X-Forwarded-Proto https;
  proxy_read_timeout 90;
}

and i make send test by coinbasecommerce.

i get Http 502 error.

what wrong? can someone help me.