Expose number of active connections as a public API

[Remy Suen]

http-server/src/Driver/ConnectionLimitingClientFactory.php

Lines 47 to 58 in b9f6a9e

 if ($this->clientsPerIp[$bytes] >= $this->connectionsPerIpLimit) { 
     if (isset($bytes[4])) { 
         $ip .= "/56"; 
     } 
  
     $this->logger->warning( 
         "Client denied: too many existing connections from {$ip}", 
         ['local' => $socket->getLocalAddress()->toString(), 'remote' => $address->toString()], 
     ); 
  
     return null; 
 } 

We're using amphp to create a WebSocket server. We are intermittently seeing Client denied messages in our logs. We would like to expose the current number of active connections as a Prometheus gauge and then have Kubernetes evaluate that number to automatically scale up the number of pods so we can handle more connections.

Is this currently possible or would we first need a way to collect the number of active connections from ConnectionLimitingClientFactory first? Alternatively, can we implement this ourselves via some kind of counter++ and counter-- logic in some handler that guarantees our numbers will not get out of sync due to exceptions and miscellaneous networking errors?

[Niklas Keller]

Hey @rcjsuen, the code you linked is a limit per IP, not an overall limit for the server. If you reach the limits per IP, you probably don't want to scale up, but rather if you hit the overall limit of connections per server instance?

[Remy Suen]

If you reach the limits per IP, you probably don't want to scale up, but rather if you hit the overall limit of connections per server instance?

And how should I determine that I've hit the overall limit assuming I just have this one WebSocket server?