🧠 Understanding Serverless Architecture with AWS

Published on: 2022-06-02

Serverless is no longer the new kid on the block. It’s a go-to choice for startups, hobby projects, and even large-scale systems thanks to its scalability, simplicity, and cost-efficiency.

But what actually happens behind the scenes when you build a serverless application on AWS?

Let’s break it down — visually.

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🌐 What Happens When You Hit an API Endpoint?

Here’s the typical flow for a serverless REST API built on AWS:

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📝 Breakdown of Each Component

• Client – A frontend app (e.g., React, Vue) or tool like Postman makes an HTTP request.
• API Gateway – Manages routing, validation, and throttling. It’s the entry point to your backend.
• Lambda Function – Runs your business logic on-demand. You pay only per execution.
• Auth Layer – Optionally uses Amazon Cognito or custom JWT validation.
• DynamoDB – AWS’s NoSQL database. Super fast, serverless, and low-cost.
• S3 – Stores static files like images, docs, etc.
• Return JSON Response – API Gateway wraps the Lambda’s return and sends it back to the client.

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🛠 What You’d Typically Use in Stack

Purpose	Tool
API Routing	AWS API Gateway
Function Logic	AWS Lambda (TypeScript)
Database	DynamoDB / Aurora Serverless
Auth	Amazon Cognito or JWT
Deployment	Serverless Framework / CDK
Local Dev	serverless-offline

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✅ Why Go Serverless?

• 🚫 No server to maintain
• ⚡ Scales automatically
• 💸 Pay-per-use model (free tier is generous!)
• 🧱 Modular — connect to other AWS services easily
• 📦 Great fit for microservices or event-driven apps

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📦 Real-World Example: TODO App

In our recent blog on building a TODO app, we used:

• API Gateway for endpoints like POST /todos
• Lambda (with TypeScript) for logic
• DynamoDB for storing tasks
• JWT for securing access

All deployed with the Serverless Framework, and tested locally using serverless-offline.

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🧪 Bonus: Test It All Locally

If you’re building serverless apps, don’t skip local development:

npm install serverless-offline serverless-dynamodb-local --save-dev
npx serverless offline start

Now you can hit http://localhost:3000/todos just like it’s live — no AWS deploy needed until you’re ready.

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🚀 Summary

Serverless architecture is production-ready, beginner-friendly, and deeply integrated with AWS tooling. If you’re building something lightweight or fast-moving, to embrace the power of Lambda + DynamoDB.

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📋 TL;DR

• Use API Gateway + Lambda for logic
• Use DynamoDB for data
• Use Cognito or JWT for auth
• Use serverless-offline for fast local dev
• Deploy with the Serverless Framework

And draw diagrams with Mermaid to impress your future self ✨