Stateless Web App: WhatIsTheTime.com

• Public EC2 instance + Elastic IP
• Scaling vertically
• Scaling horizontally
• DNS Query on public EC2 instances without Elastic IP (Route 53: A Record)
• Add Elastic Load Balancer + Health Checks on public network, EC2 instances on private network restricted by Security Group (Route 53: Alias Record)
• Add Auto Scaling Group
• Deploy on multiple Availability Zones
• Use Reserved Capacity

Stateful Web App: MyClothes.com

• Introduce Stickiness (Session Affinity)
• Introduce User Cookies
• Introduce Server Session (ElastiCache or Amazon DynamoDB)
• Storing User Data in a database (Amazon RDS)
• Scaling Reads (Read Replicas)

Stateful Web App: MyWordPress.com

• RDS Multi AZ
• Aurora MySQL - Multi AZ - Read Replicas
• Storing images with EBS
• Add EC2 instances into multi Availability Zones
• Storing images with EFS connected to ENI on instances

Typical architecture: Web App 3-tier

Elastic Beanstalk

• Managed service that deploys and scales applications easily
• Web Server Tier vs Worker Tier