AWS Three-Tier Web Architecture: Comprehensive Setup Guide

Architecture Overview

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The three-tier web architecture is a proven design pattern that separates an application into three logical tiers:

1. Presentation Tier (Web Tier)
2. Application Tier (App Tier)
3. Data Tier (Database Tier)

Key Components

• Virtual Private Cloud (VPC)
• Subnets across multiple Availability Zones
• Internet Gateway
• NAT Gateway
• Security Groups
• Elastic Load Balancers
• EC2 Instances
• RDS Database
• S3 Bucket

1. Network Infrastructure Setup

1.1 VPC Configuration

• Create a VPC with CIDR block (e.g., 10.0.0.0/16)
• Enable DNS hostnames and support
• Use VPC Wizard or AWS Console "VPC and more" feature

Subnet Strategy

• Public Subnets (Web Tier):

  • For internet-facing resources
  • Typically in different Availability Zones
  • Associated with Internet Gateway

• Private Subnets (App and Database Tiers):

  • For internal application and database resources
  • Not directly accessible from the internet
  • Routed through NAT Gateway

1.2 Internet and NAT Gateways

• Create an Internet Gateway and attach to VPC
• Create NAT Gateway in each public subnet
• Configure route tables to direct traffic appropriately

1.3 Security Groups

Create distinct security groups for:

• Web Tier EC2 Instances
• Application Tier EC2 Instances
• Load Balancers
• RDS Database

Best Practices

• Implement least privilege principle
• Only open necessary ports
• Restrict inbound and outbound traffic

Sample Web Security Group

1.4 Route Table

2. Compute Resources

2.1 EC2 Instances and Roles

• Launch instances in private subnets
• Use Amazon Linux 2 or Amazon Linux 2023
• Create IAM roles for SSM and S3 access

Web Tier EC2

• Hosts web server and frontend
• Placed in public subnet behind load balancer

Application Tier EC2

• Hosts backend application logic
• Placed in private subnet
• Communicates with database tier

3. Database Tier

3.1 RDS Configuration

• Use Amazon Aurora MySQL
• Multi-AZ deployment for high availability
• Create subnet group across multiple AZs

Database Setup Steps

1. Create subnet group
2. Choose Dev/Test template
3. Configure database insights
4. Set up monitoring (optional)

3.2 Database Configuration

-- Create database
CREATE DATABASE webappdb;

-- Create transactions table
CREATE TABLE transactions (
    id INT NOT NULL AUTO_INCREMENT,
    amount DECIMAL(10,2),
    description VARCHAR(100),
    PRIMARY KEY(id)
);

-- Insert sample data
INSERT INTO transactions (amount, description) 
VALUES 
    (400, 'groceries'),
    (100, 'class'),
    (200, 'other groceries'),
    (10, 'brownies');

4. Storage and Code Deployment

4.1 S3 Bucket

• Create S3 bucket for application code
• Use versioning and encryption
• Configure appropriate IAM policies

4.2 Code Deployment

# Clone repository
git clone https://github.com/Naveen3251/AWS_3Tier.git

# Update database configuration
# Edit app-tier/DbConfig.js with:
# - RDS endpoint
# - Database credentials
# - Database name (webappdb)

5. Application Setup

5.1 Node.js Configuration

# Install Node Version Manager (NVM)
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.38.0/install.sh | bash

# Install Node.js
nvm install 16
nvm use 16

# Install PM2 process manager
npm install -g pm2

# Install application dependencies
npm install

# Start application
pm2 start index.js
pm2 startup
pm2 save

5.2 Verification Endpoints

• Health Check: GET /health
• Transactions: GET /transaction

6. Internal Load Balancing and Auto Scaling

Create Target Group:

Create Load Balancer:

Review

Launch Template:

Load Balancer:

Update Config File
Web Instance Deployment
Configure Web Instance

7. Monitoring and Maintenance

• Enable AWS CloudWatch metrics
• Set up alarms for resource utilization
• Regularly update and patch instances
• Implement backup strategies

Estimated Costs

• Monitor resources using AWS Cost Explorer
• Consider using AWS Budgets
• Leverage AWS Free Tier for learning