Serverless Made Simple: How I Use AWS Lambda, API Gateway & DynamoDB

A practical guide to building real-world serverless applications using AWS Lambda, API Gateway, and DynamoDB. Includes architecture examples, code snippets, and project insights.

Introduction

Serverless is more than a buzzword—it’s a powerful model that lets developers focus on writing code without worrying about infrastructure. In this post, I’ll walk through how I use AWS Lambda, API Gateway, and DynamoDB together to build scalable, cost-efficient backends for real-world projects like Driver-Sync and Car-Keeper.

Why Serverless?

• No server maintenance
• Built-in scalability
• Event-driven execution
• Pay-as-you-go pricing
• Seamless integration with AWS ecosystem

Architecture Overview

A typical architecture I use looks like this:

• Client (React/React Native) → API Gateway → Lambda Functions → DynamoDB
• Authentication handled with AWS Cognito
• File uploads go through S3 signed URLs

Include a diagram (optional) with arrows showing the flow.

API Gateway + Lambda

• I use AWS CDK or SST to define APIs.
• Each route maps to a Lambda function or handler inside a monolithic app using Express.js or aws-lambda-router.

Sample code:

// Lambda handler using Express.js
app.get("/drivers", async (req, res) => {
  const data = await db.queryDrivers();
  res.json(data);
});

Working with DynamoDB

• Store structured and unstructured data
• Use single-table design where practical
• Strongly recommend defining access patterns before schema

Sample schema:

{
  "PK": "DRIVER#123",
  "SK": "PROFILE",
  "name": "John Doe",
  "license": "ABC123"
}

Performance & Cost Optimization

• Cold start mitigation tips
• Use provisioned concurrency if needed
• Keep Lambda payloads small
• Use batch writes for DynamoDB

Common Pitfalls & Fixes

• CORS issues? Define exact origins in API Gateway
• Hitting DynamoDB limits? Use exponential backoff with retries
• Need relational data? Integrate with RDS Proxy when needed

Real Project Use Case: Driver-Sync

• Mobile pre-trip inspection app
• Uses Cognito for login
• APIs for vehicle assignment, reporting, and checklist syncing
• All backed by Lambda + DynamoDB + S3

Conclusion

AWS serverless tools like Lambda, API Gateway, and DynamoDB enable developers to ship fast, scale painlessly, and maintain less infrastructure. With careful planning and the right patterns, serverless becomes a productivity multiplier.