GitHub PHP webhook to auto-pull on repo push (w/ secret key)

github_deploy.php

<?php
  $SECRET_KEY = '';
  $header = getallheaders();
  $hmac = hash_hmac('sha1', file_get_contents('php://input'), $SECRET_KEY);

  if ( isset($header['X-Hub-Signature']) && $header['X-Hub-Signature'] === 'sha1='.$hmac ) {
    $payload = json_decode( file_get_contents('php://input'));
    shell_exec( 'cd /home4/pbshawa1/public_html/wordpress && git reset --hard HEAD && git pull' );
  }

?>
<h1>Aloha!</h1>