Serverless Best Practices and Monitoring

Building a serverless application that works in development is one thing — running it reliably in production is another. This lesson covers the operational best practices, monitoring strategies, security hardening, performance optimisation, and cost management techniques that separate prototype-quality serverless applications from production-grade systems.

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Performance Best Practices

1. Minimise Cold Starts

Cold starts are the most common performance concern in serverless. Apply these techniques:

Technique	Impact	Cost
Use lightweight runtimes (Node.js, Python)	High	Free
Reduce deployment package size	High	Free
Initialise SDK clients outside the handler	High	Free
Use Provisioned Concurrency	Very High	Paid
Avoid VPC unless necessary	Medium	Free
Use ARM64 (Graviton2) architecture	Medium	20% cheaper

// GOOD: Initialise outside the handler (runs once during INIT)
import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient, GetCommand } from '@aws-sdk/lib-dynamodb';

const client = DynamoDBDocumentClient.from(new DynamoDBClient({}));
const TABLE = process.env.TABLE_NAME;