Simple PHP based web-hook multiplexer / relay service

WebhookRelay.php

<?php

// A map of "request_path" => Array of target urls.
// Any request coming to "request_path" will be forwarded/relayed to all the urls specified in its value
// fowarding is done asynchronously and concurrntly. 
$conf = [
    '/mywebook1' => [
        'https://testing.myapp.local/webhook/webhook1',
        'https://dev.myapp.local/webhook/webhook1',
    ],
    '/mywebook2' => [
        'https://testing.myapp.local/hooks/hook2',
        'https://dev.monitoring.local/webhooklogger/hook2',
    ],

];

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

use GuzzleHttp\Client;
use GuzzleHttp\Promise;



/**
 * 
 * @property Array $relayConf
 */
class WebhookRelay
{
    public function __construct($relayConf)
    {
        $this->relayConf = $relayConf;
    }

    function sendReq($url, $method = "GET", $query = [], $body = "", $headers = [])
    {
        return (new Client())->requestAsync($method, $url, [
            'query' => $query,
            'body' => $body,
            'headers' => $headers,
        ]);
    }

    function relayReq($path)
    {
        $relayConf = $this->relayConf;
        if (!isset($relayConf[$path])) {
            error_log("webhook: no urls found for " . $path);
            return;
        }

        $headers = getallheaders();
        unset($headers['Host']);
        unset($headers['Accept-Encoding']);
        $query = $_GET;
        $method = $_SERVER['REQUEST_METHOD'];
        $body = file_get_contents('php://input');

        $urls = $relayConf[$path];
        $allTasks = [];
        foreach ($urls as $url) {
            $allTasks[] = $this->sendReq($url, $method, $query, $body, $headers);
        }

        return Promise\Utils::unwrap($allTasks);
    }
}

// First send response to upstream server
ob_start();
echo json_encode(['success' => true]);
$size = ob_get_length();
header('Content-type: application/json');
header("Content-Length: {$size}");
header("Connection: close");
ob_end_flush();
ob_flush();
flush();

// Then do the processing
$path = $_SERVER['PATH_INFO'];
$path = rtrim($path, '/');
$webhookRelay = new WebhookRelay($conf);
$webhookRelay->relayReq($path);