I have a set of IoT devices reporting their current status to MQTT when online. Rather than storing the status, which can update frequently, in a database, I wanted something ephemeral like a GenServer.

My question though is how should I structure the GenServer? It seems naive to have every single device report it’s state to a single GenServer instance. On the other end, it seems like overkill to have a GenServer for every device (thousands of devices).

If it helps, the data is rather simple from each device:

{
  online: {boolean},
  active: {boolean},
  activated_at: {timestamp},
  expiring_at: {timestamp},
  device_uid: {uuid}
}

What this data will be used for?

For now a simple dashboard showing all devices that are known and showing their current state.