Building for the Cloud

AWS offers 200+ services. The challenge isn't what to use—it's knowing when and how to combine them effectively.

The Core Services

Pattern 1: Three-Tier Architecture

The classic, battle-tested approach:

┌─────────────────────────────────────────┐
│           Application Load Balancer     │
└─────────────────┬───────────────────────┘
                  │
┌─────────────────▼───────────────────────┐
│          EC2 Auto Scaling Group         │
│     ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐    │
│     │ Web │ │ Web │ │ Web │ │ Web │    │
│     └─────┘ └─────┘ └─────┘ └─────┘    │
└─────────────────┬───────────────────────┘
                  │
┌─────────────────▼───────────────────────┐
│     RDS Multi-AZ (Primary + Standby)    │
└─────────────────────────────────────────┘

Pattern 2: Serverless Event-Driven

Zero servers to manage:

API Gateway → Lambda → DynamoDB
                  ↓
              SQS Queue → Lambda → S3
                              ↓
                          SNS → Email

Example Lambda Function

import json
import boto3

def handler(event, context):
    dynamodb = boto3.resource('dynamodb')
    table = dynamodb.Table('Users')

    response = table.put_item(
        Item={
            'user_id': event['user_id'],
            'name': event['name'],
            'created_at': str(datetime.now())
        }
    )

    return {
        'statusCode': 200,
        'body': json.dumps('User created!')
    }

Pattern 3: Microservices with ECS

Container orchestration made simple:

# ECS Task Definition
{
  "family": "web-service",
  "containerDefinitions": [
    {
      "name": "web",
      "image": "my-app:latest",
      "portMappings": [
        {
          "containerPort": 3000,
          "hostPort": 3000
        }
      ],
      "memory": 512,
      "cpu": 256
    }
  ]
}

Cost Optimization Tips

1. Right-Size Instances

Don't pay for unused capacity: - Use Compute Optimizer recommendations - Start small, scale up as needed - Consider Graviton (ARM) instances for 40% savings

2. Reserved vs Spot vs On-Demand

3. S3 Storage Classes

Frequent Access → S3 Standard
Infrequent → S3 IA (40% cheaper)
Archive → S3 Glacier (80% cheaper)
Deep Archive → Glacier Deep (95% cheaper)

Security Best Practices

• 🔐 IAM Least Privilege - Only grant what's needed
• 🛡️ Security Groups - Stateful firewalls
• 📝 CloudTrail - Audit all API calls
• 🔍 GuardDuty - Threat detection

My Go-To Stack

For most new projects, I start with:

1. Route 53 - DNS
2. CloudFront - CDN
3. ALB - Load balancing
4. ECS Fargate - Containers without servers
5. RDS Aurora - Managed MySQL/PostgreSQL
6. ElastiCache - Redis for caching
7. S3 - Static assets

Build for scale from day one, but only pay for what you use!