<?php
header('Content-Type: text/plain; charset=UTF-8');

$https = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') ? 'YES' : 'NO';

echo "OK:
echo "Host: " . ($_SERVER['HTTP_HOST'] ?? 'unknown') . "\n";
echo "URI: " . ($_SERVER['REQUEST_URI'] ?? 'unknown') . "\n";
echo "HTTPS: $https\n";
echo "Remote: " . ($_SERVER['REMOTE_ADDR'] ?? 'unknown') . "\n";
echo "Server: " . ($_SERVER['SERVER_SOFTWARE'] ?? 'unknown') . "\n";
echo "PHP: " . PHP_VERSION . "\n";
PHP