Lets get Started!..
Here’s a breakdown of all the Terraform files needed to build a three-tier web application (Presentation, Application, and Database layers) using AWS as the cloud provider.

3-Tier Web Application — Overview
A 3-tier web application architecture divides an application into three separate logical layers, where each layer is responsible for a specific function.

This architecture enhances modularity, scalability, security, and ease of maintenance.

  1. Presentation Tier (Web Tier) Role: Interface between users and the application. Technology: HTML, CSS, JavaScript, React, Angular, Vue.js. Hosted on: S3 + CloudFront, EC2 with Nginx/Apache. Example: Login page, product listing page, user dashboard.
  2. Application Tier (Logic Tier) Role: Handles business logic and processing. Technology: Node.js, Java Spring Boot, Python Flask/Django, .NET Core. Hosted on: EC2, ECS, EKS, or AWS Lambda. Example: Processing login credentials, fetching user order history.
  3. Data Tier (Database Tier) Role: Manages storage and retrieval of data. Technology: Amazon RDS (MySQL, PostgreSQL), DynamoDB, MongoDB. Hosted on: Private Subnet for security. Example: Stores user profiles, orders, inventory data.

This setup will include:

Architecture Components:
VPC with public and private subnets

Internet Gateway & NAT Gateway

Route Tables

Security Groups

EC2 instances for web and app tiers (in Auto Scaling Groups with Launch Templates)

Application Load Balancer

RDS (MySQL/PostgreSQL) in private subnet

Directory Structure:

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Architecture Diagram:

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Have attached My github repository for Terraform Modules

https://github.com/VenkatVk4622/3tierwebapplication.git
Once added the above tf files

terraform plan > terraform validate> terraform apply or terraform apply -auto -approve
Follow the above commands in your VS Code to Deploy the above services in your AWS Console!

Final Summary
In this blog, we explored how to design and deploy a secure, scalable, and modular 3-tier web application architecture on AWS using Terraform.

By separating the infrastructure into Presentation (Web), Application (App), and Data (DB) tiers, we achieved better maintainability, enhanced security, and independent scalability.

Using Terraform’s Infrastructure as Code (IaC) capabilities, we automated the provisioning of VPC, subnets, EC2 instances, security groups, RDS, and secrets.

This architecture not only follows industry best practices but also lays a strong foundation for modern, production-ready cloud applications.

Venkat C S