Package "ctw/ctw-middleware-generatedby"

PSR-15 middleware to create a UUID v5 (Universally Unique Identifiers) and add it to the X-Generated-By header of the response. The UUID is created using the server IP address i.e. $_SERVER['SERVER_ADDR'] and domain name of the application i.e. $_SERVER['SERVER_NAME'].

This functionality is useful when multiple applications servers are running behind a load balancer. By inspecting the X-Generated-By header, it is possible to find out exactly which application server processed the request without exposing its public IP addresses.

middlewares/utils provides utility classes for working with PSR-15 and ramsey/uuid provides UUID v5 generation.

Installation

Install the middleware using Composer:

$ composer require ctw/ctw-middleware-generatedby

Standalone Example

use Ctw\Middleware\GeneratedByMiddleware\GeneratedByMiddlewareFactory;
use Laminas\ServiceManager\ServiceManager;
use Middlewares\Utils\Dispatcher;
use Middlewares\Utils\Factory;

$container = new ServiceManager();
$factory   = new GeneratedByMiddlewareFactory();

$generatedByMiddleware = $factory->__invoke($container);

$serverParams = [
    'SERVER_ADDR' => '1.1.1.1',
    'SERVER_NAME' => 'www.example.com',
];
$request      = Factory::createServerRequest('GET', '/', $serverParams);
$stack        = [
    $generatedByMiddleware,
];
$response     = Dispatcher::run($stack, $request);

$uuid = $response->getHeaderLine('X-Generated-By');

dump($uuid);  // 78ac0e14-0f2b-529e-81e2-a0f50f6029c5

Example in Mezzio

The middleware has been extensively tested in Mezzio.

After using Composer to install, simply make the following changes to your application's configuration.

In config/config.php:

$providers = [
    // [..]
    \Ctw\Middleware\GeneratedByMiddleware\ConfigProvider::class,
    // [..]    
];

In config/pipeline.php:

use Ctw\Middleware\GeneratedByMiddleware\GeneratedByMiddleware;
use Mezzio\Application;
use Mezzio\MiddlewareFactory;
use Psr\Container\ContainerInterface;

return function (Application $app, MiddlewareFactory $factory, ContainerInterface $container): void {
    // [..]
    $app->pipe(GeneratedByMiddleware::class);
    // [..]
};

You can then test to ensure that the X-Generated-At header is in the returned HTTP headers with:

curl -I -k https://www.example.com.development

If you see the X-Generated-At header, the middleware is correctly installed:

date: Wed, 17 Mar 2021 05:59:26 GMT
x-generated-by: ce9f95cf-9ce3-5c0d-8c59-c579f2e474fb
content-type: text/html; charset=utf-8