I have PHP-FPM pool with such configuration blocks:
... listen = 0.0.0.0:9000 ... pm.status_path = /status ... I'm getting
curl: (56) Recv failure: Connection reset by peer while trying
curl 0.0.0.0:9000/status .
PHP-FPM instance I try to interact with is containerized and curl action I do from docker container.
You're trying to talk to PHP-FPM socket with HTTP; that makes no sense, PHP-FPM is a FastCGI server, not a HTTP server.
If you're not in the same network namespace, connecting to 0.0.0.0 isn't sensible at all; that's not a regular IP address, but just a way to tell a listening socket to listen on all interfaces (on Linux). It does translate to the same address of 127.0.0.1 when using it as connection address, but if the 127.0.0.1 inside a container is not usuall the same as the 127.0.0.1 outside the container, and container engines typically do not just bind a published port to the wildcard address.
curl was run in the same container as the PHP server. In any case, my comment was about “but just a way to tell a listening socket to listen on all interfaces” — that’s one of the uses of 0.0.0.0, but it’s not the only one. PHP-FPM doesn't use HTTP for its communication it uses a FastCGI protocol. When you try to access it directly with curl on port 9000, you're trying to speak HTTP to a service that expects FastCGI protocol.
PHP-FPM functions as the backend interpreter for PHP, handling script execution, while the web server takes care of receiving requests and returning results to browsers.
Set up a web server Nginx/Apache in front of PHP-FPM
Install a FastCGI client like Fast CGI Client or fcgi-client
Use a PHP-FPM specific tool
Make sure the containers are on the same network
Verify the port is properly exposed/published
Check if there are any firewalls between containers