Cloud Architecture

Cloud Architecture

Design resilient, cost-effective cloud architectures.

Design Pillars

| Pillar | Focus | Pattern |

|--------|-------|---------|

| Reliability | Fault tolerance, recovery | Multi-AZ, redundancy, auto-healing |

| Security | Defense in depth | IAM, encryption, network segmentation |

| Cost | Efficiency, waste reduction | Right-sizing, reserved instances, autoscaling |

| Performance | Speed, scalability | CDN, caching, horizontal scaling |

| Operational | Manageability, automation | IaC, CI/CD, runbooks |

VPC Design

Multi-Tier Architecture

Internet → WAF → ALB → App Tier (private) → DB Tier (private)
                      ↕
                 Auto Scaling

Best Practices

• Use multiple AZs (minimum 3)
• Private subnets for apps and databases
• Public subnets only for load balancers and bastions
• NACLs for subnet-level rules, Security Groups for instance-level
• VPC peering or Transit Gateway for multi-VPC

High Availability

• Compute: Multi-AZ Auto Scaling groups, spot + on-demand mix
• Database: Multi-AZ RDS, Aurora read replicas
• Storage: S3 (11 9's durability), EBS snapshots
• DNS: Route53 with health-check based failover
• CDN: CloudFront/CloudFlare for global distribution

Disaster Recovery

| Strategy | RTO | RPO | Cost |

|----------|-----|-----|------|

| Backup & Restore | Hours | 24h | $ |

| Pilot Light | Minutes | 1h | $$ |

| Warm Standby | Seconds | Minutes | $$$ |

| Active-Active | Seconds | Seconds | $$$$ |

DR Plan

• Document runbooks for each scenario
• Test failover quarterly
• Automate recovery with IaC
• Store backups in separate region
• Encrypt everything

Cost Optimization

• Right-size instances (use Compute Optimizer)
• Reserved Instances / Savings Plans for steady state
• Spot instances for fault-tolerant workloads
• S3 lifecycle policies (transition to Glacier)
• Delete unused resources (EBS, EIP, ELB)
• Monitor with Cost Explorer + budgets + alerts