proxy.php

<?php

/* Config */

$upstream_base_url = 'http://127.0.0.1:9000';
$timeout = 5; // seconds
$latency = 0; // simulate latency; seconds


/* Read incoming request */

$request_method = $_SERVER['REQUEST_METHOD'];
$request_uri = $_SERVER['REQUEST_URI'];
$request_headers = getallheaders();
$request_body = file_get_contents('php://input');


/* Simulate latency */

if ($latency) {
	sleep($latency);
}


/* Forward request */

$url = $upstream_base_url . $request_uri;
$headers = array();
foreach ($request_headers as $key => $value) {
	$headers[] = $key . ': ' . $value;
}

$ch = curl_init();
curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $request_method);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POSTFIELDS, $request_body);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);

if ($response === false) {
	header('HTTP/1.1 502 Bad Gateway');
	header('Content-Type: text/plain');
	echo 'Upstream host did not respond.';
} else {
	$header_length = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
	$response_headers = explode("\n", substr($response, 0, $header_length));
	$response_body = substr($response, $header_length);

	foreach ($response_headers as $header) {
		$header = trim($header);
		if ($header) {
			header(trim($header));
		}
	}

	echo $response_body;
}

curl_close($ch);