AWS Auto Scaling Web Server Infrastructure as Code

This project implements a scalable web server infrastructure using AWS CDK (Cloud Development Kit) that automatically adjusts capacity based on demand. It creates a secure, highly available web hosting environment with automated scaling capabilities and performance monitoring.

The infrastructure deploys a web server environment in AWS using Infrastructure as Code principles. It provisions a VPC with public subnets, configures security groups, sets up an Auto Scaling group with customizable capacity, and implements CPU-based scaling policies. The web servers are automatically configured with Apache and PHP, and deploy a sample web application from an S3 bucket.

Repository Structure

.
├── app.py                      # Main CDK application entry point
├── hawa_poc/                   # Core infrastructure code
│   └── hawa_poc_stack.py      # Main stack definition with AWS resources
├── tests/                      # Test directory
│   └── unit/                  # Unit tests for the stack
├── cdk.json                   # CDK configuration and context
├── requirements.txt           # Production dependencies
├── requirements-dev.txt       # Development dependencies
└── source.bat                # Windows virtual environment activation script

Usage Instructions

Prerequisites

• Python 3.6 or later
• AWS CLI configured with appropriate credentials
• AWS CDK CLI installed (npm install -g aws-cdk)
• An AWS account with necessary permissions
• An EC2 key pair for SSH access

Installation

1. Clone the repository and create a virtual environment:

# Linux/MacOS
python3 -m venv .venv
source .venv/bin/activate

# Windows
python -m venv .venv
source.bat

2. Install dependencies:

pip install -r requirements.txt
pip install -r requirements-dev.txt

3. Bootstrap CDK in your AWS account (if not already done):

cdk bootstrap

Quick Start

1. Deploy the stack:

cdk deploy --parameters KeyPairName=your-key-pair-name

2. The deployment will create:

• A VPC with public subnets
• Security groups for web traffic
• An Auto Scaling group of EC2 instances
• Scaling policies based on CPU utilization

More Detailed Examples

1. Customize the deployment with different instance types:

# In hawa_poc_stack.py
instance_type=ec2.InstanceType.of(ec2.InstanceClass.T3, ec2.InstanceSize.SMALL)

2. Modify scaling thresholds:

asg.scale_on_cpu_utilization(
    "CpuScaling",
    target_utilization_percent=70,  # Change from default 50%
    estimated_instance_warmup=Duration.seconds(180)
)

Troubleshooting

Common Issues:

1. Deployment Failure

• Error: "VPC limit exceeded"
  • Solution: Check AWS VPC limits in your account
  • Run: aws service-quotas get-service-quota --service-code ec2 --quota-code L-F678F1CE

2. Instance Launch Failures

• Check EC2 instance launch logs:

  aws ec2 get-console-output --instance-id <instance-id>

• Verify security group settings in AWS Console

3. Auto Scaling Issues

• Enable detailed monitoring:

  aws autoscaling describe-auto-scaling-groups --auto-scaling-group-name <asg-name>

• Check CloudWatch metrics for CPU utilization

Data Flow

The infrastructure processes web requests through a multi-tier architecture, scaling automatically based on CPU utilization metrics.

Internet --> Security Group --> Auto Scaling Group --> EC2 Instances
                                      ^
                                      |
                            CloudWatch Metrics

Component Interactions:

1. Security Group controls inbound HTTP traffic on port 80
2. Auto Scaling Group monitors instance health and CPU metrics
3. CloudWatch collects and processes metrics every minute
4. Scaling policies adjust capacity based on CPU utilization
5. EC2 instances run Apache web server with PHP support
6. User data script configures web server and deploys application
7. Instances launch in public subnets with internet access

Infrastructure

VPC Resources

• VPC with 2 Availability Zones
• Public subnets with internet connectivity
• Security group allowing HTTP traffic

Compute Resources

• Launch Template:
  • Amazon Linux 2 AMI
  • t2.micro instance type
  • 8GB EBS volume
  • User data for web server setup

Auto Scaling

• Auto Scaling Group:
  • Min: 1 instance
  • Max: 3 instances
  • Health check grace period: 60 seconds
• Scaling Policies:
  • Target tracking: 50% CPU utilization
  • Step scaling for optimized availability

Monitoring

• Detailed instance monitoring enabled
• CloudWatch metrics for CPU utilization
• Auto Scaling group metrics

Deployment

1. Prerequisites:

• AWS credentials configured
• CDK bootstrapped in target account
• EC2 key pair created

2. Deployment Steps:

cdk deploy --parameters KeyPairName=your-key-pair-name

3. Environment Variables:

• CDK_DEFAULT_ACCOUNT: AWS account ID
• CDK_DEFAULT_REGION: Target AWS region

4. Monitoring:

• Access CloudWatch dashboards for metrics
• Check Auto Scaling group activity
• Monitor EC2 instance health