.healthcheck.php

<?php
/**
 * Idealstack Healthcheck.
 *
 * This file is checked by the load balancer to see whether the site is  healthy.
 * If it returns a 500 error the site is considered unhealthy, and the site's container
 * will be rebooted.
 *
 * This default check doesn't do much except check that PHP is running.
 * You can customise this file to check other important resources
 * and return a 500 response code if they fail.  But be careful - every time
 * the check fails the site goes offline
 */

echo "OK";