Cheat Sheet: Cloud Architecture

Cloud Service Models

• IaaS (Infrastructure as a Service): You manage OS, data, apps. Provider manages networking, storage, servers. (e.g., VMs)
• PaaS (Platform as a Service): You manage apps and data. Provider manages everything else. (e.g., App Engine)
• SaaS (Software as a Service): Provider manages everything. You just consume. (e.g., Gmail)

Core Networking

• VPC: Virtual Private Cloud. Your isolated network.
• Subnets: Subdivisions of a VPC. Can be Public (internet access) or Private (no internet access).
• Load Balancer: Distributes traffic across instances to ensure availability.

High Availability & Disaster Recovery

• HA: Minimizing downtime through redundancy (e.g., Multi-AZ).
• RTO (Recovery Time Objective): Maximum time allowed to restore systems.
• RPO (Recovery Point Objective): Maximum data loss allowed (measured in time).
• DR Strategies:
  1. Backup & Restore (Slowest, Cheapest)
  2. Pilot Light
  3. Warm Standby
  4. Multi-Site Active/Active (Fastest, Most Expensive)

Cloud-Native Principles

• Microservices: Small, loosely coupled services.
• Containers: Portable environments packaging app code and dependencies.
• Serverless: Code execution without provisioning servers (e.g., Lambda/Functions).
• Immutable Infrastructure: Replacing servers rather than updating them in place.