Three-Layer AWS Architecture with Terraform

This project implements a three-layer architecture in AWS using Terraform:

1. Web Layer - Public-facing web servers in public subnets
2. Application Layer - Application servers in private subnets
3. Database Layer - RDS MySQL database in isolated database subnets

Architecture Overview

The architecture includes:

• VPC: A dedicated VPC with CIDR block 10.0.0.0/16
• Subnets: Public, private, and database subnets across multiple availability zones
• Internet Gateway: Allows internet access from public subnets
• NAT Gateway: Allows internet access from private and database subnets
• Route Tables: Configured for each subnet type
• Security Groups: Defined for web, application, and database layers
• Load Balancers: Application Load Balancers for web and application layers
• EC2 Instances: Web servers and application servers
• RDS Database: Multi-AZ MySQL database

Prerequisites

• AWS CLI configured with appropriate permissions
• Terraform v1.0.0+ installed
• SSH key pair created in AWS (referenced in the configuration)

Directory Structure

infrastructure/
├── main.tf              # Main Terraform configuration
├── variables.tf         # Input variables
├── outputs.tf           # Output values
├── modules/
│   ├── networking/      # VPC, subnets, security groups, etc.
│   ├── compute/         # EC2 instances, load balancers
│   └── database/        # RDS database
└── environments/
    ├── dev/             # Development environment configuration
    └── prod/            # Production environment configuration

Deployment Instructions

Initialize Terraform

cd infrastructure
terraform init

Deploy to Development Environment

cd environments/dev
terraform init
terraform plan
terraform apply

Deploy to Production Environment

cd environments/prod
terraform init
terraform plan
terraform apply

Security Notes

• In a production environment, improve security by:
  • Using AWS Secrets Manager or Parameter Store for database credentials
  • Restricting SSH access to specific CIDR blocks
  • Implementing a bastion host for SSH access
  • Adding AWS WAF to the web ALB
  • Enabling encryption for all data at rest and in transit

Clean Up

To destroy all resources:

cd environments/dev  # or prod
terraform destroy