How to Monitor Device Status Using Socket.IO Heartbeat Callbacks in a Multi-Node Cluster and Update Redis in Real-Time

[iakuf]

I have a system with over ten thousand devices connected via socket.io. I would like to monitor the heartbeat of these devices using socket.io's built-in heartbeat mechanism and update a timestamp for each device in Redis whenever a heartbeat is detected. This way, I can easily track which devices are currently active and know the total number of active devices.

Since my application is running on multiple Node.js cluster instances, how can I effectively monitor the heartbeats across all these instances and ensure that the heartbeat updates are consistently written to Redis? Specifically, how can I implement a callback to update Redis whenever a heartbeat is detected?

[darrachequesne]

Hi! You can listen to the heartbeat event:

io.on("connection", (socket) => {
  socket.conn.on("heartbeat", () => {
    // called after each round trip of the heartbeat mechanism
    console.log("heartbeat");
  });
});

That being said, I think relying on the connection / disconnect events might be sufficient:

io.on("connection", (socket) => {
  // persist status into Redis

  socket.on("disconnect", () => {
    // persist status into Redis
  });
});