Start the Application After Redis Connects

The application must not start accepting connections before Redis is ready when the Redis adapter is required for correct cross-instance broadcasting.

Update src/server.js to connect Redis before starting the HTTP server.

This prevents clients from connecting to an instance that has not completed adapter initialization.

Fail-Fast Startup

If Redis is a required dependency for cross-instance messaging, do not silently start in-memory mode when Redis is unavailable. Either fail startup or implement an explicitly designed degraded mode.

Updated src/server.js

import 'dotenv/config';
import express from 'express';
import { createServer } from 'node:http';
import { initializeSocket } from './config/socket.js';
import { connectRedis } from './config/redis.js';
import { registerChatEvents } from './events/chat.events.js';

const app = express();
app.use(express.json());
app.use(express.static('public'));

const httpServer = createServer(app);

async function startServer() {
  await connectRedis();

  const io = initializeSocket(httpServer);

  registerChatEvents(io);

  const PORT = process.env.PORT || 3000;

  httpServer.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`);
  });
}

startServer().catch((error) => {
  console.error('Application startup failed:', error);
  process.exit(1);
});

Connects Redis first, initializes Socket.IO with the Redis adapter, registers events, and finally starts the HTTP server.

Key Takeaways

Initialize Redis before Socket.IO.
Register event handlers before accepting connections.
Use fail-fast startup when distributed messaging is required.

Start the Application After Redis Connects

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