AWS 3 Tier Architecture

Architecture Flow

  1. User → Internet-Facing ALB → Public-ASG (Web Tier) → Private-ASG (App Tier) → RDS (DB Tier).
  2. S3 and Lambda integrated for storage and serverless workflows.
  3. SNS and CloudWatch for alerts and monitoring.

Demo video:

Step-by-Step Guide to AWS 3-Tier Architecture Implementation

1. Project Setup & VPC Configuration

  • Created a VPC (Virtual Private Cloud) to isolate resources.
  • Designed subnets:
    • Public subnets (for web tier).
    • Private subnets (for application tier and database tier).
  • Configured route tables, internet gateways, and NAT gateways for connectivity.

2. Security Groups Configuration

  • Public-SG:
    • Allowed inbound traffic from 0.0.0.0/0 (internet) for HTTP/HTTPS access.
  • Private-SG:
    • Restricted inbound traffic to only instances associated with Public-SG.
  • RDS-SG:
    • Allowed access exclusively from Private-SG for database security.

3. RDS Subnet Group Setup

  • Created a DB subnet group for Amazon RDS.
  • Assigned private subnets to the subnet group to host the database tier (e.g., MySQL/PostgreSQL).

4. Auto Scaling Groups (ASG)

  • Public-ASG:
    • Launched EC2 instances in public subnets (web tier).
    • Configured scaling policies based on CPU/memory usage.
  • Private-ASG:
    • Launched EC2 instances in private subnets (application tier).
    • Ensured instances are only accessible via Public-SG.

5. Load Balancers & Target Groups

  • Internet-Facing Application Load Balancer (ALB):
    • Deployed in public subnets.
    • Forwarded traffic to Public-ASG instances via target groups.
  • Internal Load Balancer (optional):
    • Used for communication between application tier (private) and database tier.

6. Web Application Deployment

  • Hosted a website on Public-ASG instances.
  • Validated load balancing by refreshing instances and confirming traffic distribution.

7. Accessing Private Resources

  • Bastion Host:
    • Used a public EC2 instance (in Public-SG) to SSH into private instances (Private-SG).
  • RDS Connection:
    • Accessed the database from the application tier (private instances).
  • S3 Integration:
    • Uploaded live_demo.txt to an S3 bucket from the public server.

8. S3, RDS, and SNS Setup

  • S3 Bucket:
    • Created for static assets or file storage.
  • RDS Database:
    • Configured a relational database (e.g., MySQL) in the private subnet group.
  • SNS Notifications:
    • Sent alerts (e.g., scaling events) to a registered email via Amazon SNS.

9. Serverless Components

  • Lambda Function:
    • Deployed for event-driven tasks (e.g., processing S3 uploads).
  • SQS Queue:
    • Used to decouple components (e.g., sending messages between services).

10. Monitoring & Logging

  • CloudWatch Logs:
    • Tracked metrics and logs for EC2, RDS, Lambda, and ASG.

Terraform Implementation

Highly Available AWS 3 Tier Terraform Template

1. Configure the AWS CLI

$ aws configure
AWS Access Key ID [****************MRAE]: 
AWS Secret Access Key [****************6wNJ]:

2. Install and Validate Terraform

Install Terraform using your system’s package manager or download it from the official website.

Linux (Ubuntu/Debian):

sudo apt-get update && sudo apt-get install -y gnupg software-properties-common
wget -O- https://apt.releases.hashicorp.com/gpg | gpg --dearmor | sudo tee /usr/share/keyrings/hashicorp-archive-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
sudo apt update && sudo apt install terraform

Validate Installation:

terraform -version

This should display the installed Terraform version (e.g., Terraform v1.5.7), confirming a successful installation.

3. Clone the Repo and cd

git clone https://github.com/rizvifazi/aws-ha-tf.git

4. Create a key pair named tf-keypair in your AWS account

  • We are taking a manual approach to create the keys for our convenience.
  • This key-pair will be used by the terraform script to create resources.

5. Execute terraform commands

# Intialises provider plugin and modules  
terraform init  
# Validates the configuration files  
terraform validate  
# Shows the execution plan  
terraform plan  
# Creates the infrastructure  
terraform apply