Ping script for PHP/MySQL application that uses dotenv

ping.php

<?php

require_once(__DIR__ . '/vendor/autoload.php');

$dotenv = new Dotenv\Dotenv(dirname(__FILE__));
$dotenv->load();

define('DB_NAME', getenv('DB_NAME'));
define('DB_USER', getenv('DB_USER'));
define('DB_PASS', getenv('DB_PASS'));
define('DB_HOST', getenv('DB_HOST'));

if ( ! mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME)) {
    echo 'database error';
} else {
    echo 'pong';
}