I stumbled over https://roadrunner.dev/ already some longer time ago but just now took some time to play with Roadrunner and Flow.
It should be quite possible to integrate Flow via the Roadrunner workers and have a PSR-7 request handler. I got it working (Neos frontend output basically) in an hour - but memory/state leaks und proper shutdown / cleanup is another story
I always find it hard to run PHP applications with PHP-FPM etc. in the long run. Also container setups either have to use multiple processes (e.g. Supervisord) or be composed of multiple containers (e.g. FPM + Nginx) which adds unnecessary complexity. Single (root) process applications are much easier to handle IMHO. We could also get rid of a lot of caching when (optionally) embracing this kind of architecture.
My first naive approach results in response times of <10ms for cached requests with the demo site, which would be very nice. But performance is not my main concern here - I’d rather reduce operational complexity. Having less resource requirements wouldn’t hurt though.
Is anyone interested in pursuing this topic further?