Allow access to ServerRequest connection for "raw" response?

[andig]

We have a use case where we receive HTTP requests for passing to downstream applications- basically a load balancer. That request needs be parsed and headers modified- so a good case for the HTTP server.

For the downstream application I'm not interested in the actual response semantics, I'd just want to pipe back to the original requester what the downstream sends.

Not sure this is entirely too specific, but would it be possible to return e.g. a stream instead of a Response for use in Server->handleRequest?

[ssipos90]

+1, interested

[ssipos90]

I think you can do $downstreamResponse->pipe($originalResponse) or something similar.

[ssipos90]

The other way around.

[clue]

Thanks for raising this interesting question!

I'm not sure I follow, but it looks like you may want to look into examples/4. The Response class allows you to add any stream as a response body.

I hope this helps 👍

If you feel anything's missing, please provide a simple gist, some pseudo code / overview would be much appreciated and I'm happy to look into this 👍

[andig]

Thank you @clue for looking into this. I've sketched three drafts I could think of that would allow my use case without reinventing larger parts of the server. Option 1 would require some changes to the server response handling, options 2 and 3 require the additional $requestor parameter:

public function onRelay(ServerRequestInterface $request, Connection $requestor)
{
    // open slave connection
    $stream = @stream_socket_client($slave['host'], $errno, $errstr, $this->timeout);
    $connection = new \React\Socket\Connection($stream, $this->loop);

    // pipe request to slave
    $connection->write(Psr7Implementation\str($request));
    $request->getBody()->pipe($connection);

    // pipe response to master - alternative 1
    return $connection;
    
    // pipe response to master - alternative 2
    $connection->on(
        'data',
        function ($buffer) use ($requestor) {
            $requestor->write($buffer);
        }
    );

    // pipe response to master - alternative 3
    $connection->pipe($requestor);
}

Another valid approach might be subclassing the server instead.

Am I making sense here?

[clue]

This is very valid use case indeed 👍 However, it's my understanding that this particular code would best be implemented by using an HTTP client in your HTTP request handler so that your server essentially works as a proxy server. The HTTP client will return a "normal" ResponseInterface that can directly be returned (or modified) by the server callback so that this requires literally zero effort on the server side.

This allows the server to follow "normal" HTTP semantics (request-response-cycle), header validation and automatic Transfer-Encoding etc. and to manage the underlying connections to allow persistent connections via #39 in the future.

This will also be significantly easier once the HTTP client will be merged as part of this package via #148.

Do you feel something's missing here or does this cover your use case? 👍

[andig]

Do you feel something's missing here or does this cover your use case?

I'm closing this issue now. After client has PSR-7 semantics I'll need to recheck if the approach is feasible especially in the light of async body streams.