(X-User-Type) How to make Flarum more cache friendly?

Prcek

Flarum's cached API takes under 100 ms, uncached >300 ms on fast metal, but most often I see around 700 ms to 3-6 seconds on forums with dozens of extensions enabled. Talking about caching is definitely legit.

Unfortunately, it seems impossible to find out just from HTTP headers if responses are coming for a logged user or guest. In both cases, Flarum sets the session ID in a cookie. As I wrote in another thread, forcing the cache server to query Redis or another source for the session ID status is anti-pattern. If I missed something, I apologize and ask for a straightforward solution.

In doing so, we don't need too. No need to implement ESI right away, although that would be great. Just something like the HTTP header X-User-Type:logged is sufficient. Only one header if we don't want to deal with ESI and Cache-Control.

luceos

Prcek You can create a custom middleware using the root extend.php to append that header to the browser output.

SychO

Yup, something along the lines of: (untested)

extend.php

use Flarum\Extend;

return [

    (new Extend\Middleware('forum'))
        ->add(CacheIndicationHeaderMiddleware::class),

    (new Extend\Middleware('api'))
        ->add(CacheIndicationHeaderMiddleware::class),

];

CacheIndicationHeaderMiddleware.php

use Flarum\Http\RequestUtil;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;

class CacheIndicationHeaderMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        $actor = RequestUtil::getActor($request);

        $response = $handler->handle($request);

        return $response->withAddedHeader('X-User-Type', $actor->isGuest() ? 'guest' : 'logged-in');
    }
}

Prcek

SychO Thank you.

Yes, ChatGPT 4 generated an almost identical code for me, it just didn't use the ternary operator. To reduce the network overhead, I'll probably leave the X-User-Type for the logged user only.

By the way, ChatGPT 4 has a very good knowledge of Flarum codebase until version 1.0.0 and plays very well with Composer and local repositories.

I now have a working injection of the HTTP X-User-Type header. I will make a reference configuration of Varnish VCL and will share experience 👷🏻‍♂️