How to Connect MongoDB to a Node.js Application with Mongoose (Handling Retries & Disconnections)

const mongoose = require('mongoose');

const connectDB = async () => {
  try {
    const conn = await mongoose.connect(process.env.MONGODB_URI, {
      maxPoolSize: 10, // Maintain up to 10 socket connections
      serverSelectionTimeoutMS: 5000, // Timeout after 5s instead of hanging
      socketTimeoutMS: 45000, // Close sockets after 45s of inactivity
    });

    console.log(`✅ MongoDB Connected: ${conn.connection.host}`);
  } catch (error) {
    console.error(`❌ MongoDB connection error: ${error.message}`);
    process.exit(1); // Exit process with failure
  }
};

// Event Listeners for Lifecycle Monitoring
mongoose.connection.on('disconnected', () => {
  console.warn('⚠️ MongoDB disconnected! Attempting reconnect...');
});

mongoose.connection.on('error', (err) => {
  console.error('⚠️ MongoDB runtime error:', err);
});

module.exports = connectDB;