Project: Build a Serverless App with Lambda, API Gateway and DynamoDB (Source Code)

By Ravindra Bagale, trainer · LinkedIn · Last updated: 23 October 2026

1. What you build

A single-page Notes app: list notes, add a note, delete a note. No login in the lab version (add Cognito later). Primary backend is Node.js Lambda; the zip also has a Python handler twin.

Download: serverless-notes-app.zip — contains public/ (UI), lambda/index.mjs (Node), lambda/handler.py (Python twin), README.md, and a sample IAM policy.

2. Architecture pieces

3. Lab: deploy click by click

How to do it (step by step)

Region ap-south-1. Replace yourname with your short name. Keep the free tier in mind.

A. DynamoDB table

1. Create table yourname-notes. PK: noteId (String). On-demand. No sort key.
2. Wait until Active.

B. IAM role for Lambda

1. IAM → Roles → Create role → Trusted entity AWS service → Use case Lambda.
2. Attach AWSLambdaBasicExecutionRole. Create role name yourname-notes-lambda-role.
3. Open the role → Add permissions → Create inline policy → JSON:

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Action": ["dynamodb:PutItem","dynamodb:GetItem","dynamodb:DeleteItem","dynamodb:Scan"],
    "Resource": "arn:aws:dynamodb:ap-south-1:ACCOUNT_ID:table/yourname-notes"
  }]
}

Replace ACCOUNT_ID and table name. Why Scan: the lab lists all notes with Scan for simplicity (fine under hundreds of items). For production, add userId PK and Query.

C. Lambda function

1. Create function yourname-notes-api, Runtime Node.js 20.x, use existing role yourname-notes-lambda-role.
2. Upload from the zip: copy lambda/index.mjs into the editor (or zip the file as index.mjs at the root and upload). Handler: index.handler.
3. Configuration → Environment variables: TABLE_NAME=yourname-notes.
4. Memory 256 MB, Timeout 10 s. Deploy.

D. HTTP API

1. API Gateway → Create HTTP API → name yourname-notes-http → integrate Lambda yourname-notes-api.
2. Routes: GET /notes, POST /notes, DELETE /notes/{id} → same Lambda.
3. CORS: Allow origin * (lab), methods GET,POST,DELETE,OPTIONS, headers content-type.
4. Create. Copy the Invoke URL as API_BASE.
5. Test: curl -s $API_BASE/notes → []. Then POST one note.

curl -s -X POST "$API_BASE/notes" -H 'content-type: application/json'   -d '{"text":"Finish Lambda chapter"}'
curl -s "$API_BASE/notes"

E. Front end on S3 + CloudFront

1. In public/app.js set const API_BASE = "https://YOUR_API"; (no trailing slash).
2. Create bucket yourname-notes-web, Block Public Access on (CloudFront OAC will read it).
3. Upload index.html, app.js, styles.css from public/.
4. CloudFront distribution: origin = the bucket (REST endpoint), OAC recommended, Viewer redirect HTTP→HTTPS, default root object index.html. Attach the bucket policy CloudFront shows.
5. Open the CloudFront URL → add a note → refresh → delete. DevTools Network should show 200 from API.

F. Optional Python twin

Create a second function with lambda/handler.py, same env and role, point a route or stage at it to compare runtimes.

Cleanup (do this)

1. Disable then delete the CloudFront distribution (waits several minutes).
2. Empty and delete the S3 website bucket.
3. Delete the HTTP API. Delete the Lambda function(s).
4. Delete the DynamoDB table. Delete the IAM role and inline policy.
5. Confirm Billing → Cost Explorer shows only tiny charges (usually free-tier covered).

4. Interview angles from this project

Revision, comparison and interview cards

Revise this lesson in a few minutes. Save the cards on your phone or download them as PNG files. The QR code on each card opens this lesson.

More cards: Ravi Sir's Cards.