Create a DevOps Infrastructure Setup

Design a complete DevOps infrastructure setup for the following:

Application type: [web app / API / microservices / data pipeline / other]
Cloud provider: [AWS / GCP / Azure / DigitalOcean / other]
Expected traffic: [small — under 1000 DAU / medium / large — millions]
Budget: [minimal / startup / scale-up / enterprise]
Tech stack: [describe languages, databases, services]
Availability requirement: [best effort / 99.9% / 99.99%]
Compliance requirements: [GDPR / HIPAA / SOC2 / none]
Current state: [greenfield / migrating existing / scaling existing]
Infrastructure as code preference: [Terraform / Pulumi / CloudFormation / none yet]

Provide a complete infrastructure design:

NETWORK ARCHITECTURE:
- VPC/network design
- Public and private subnet strategy
- Load balancer configuration
- CDN setup
- DNS configuration

COMPUTE LAYER:
- Server/container choice and sizing
- Auto-scaling configuration
- Container orchestration (if applicable)
- Serverless components (if applicable)

DATABASE AND STORAGE:
- Primary database setup and sizing
- Read replica configuration
- Backup strategy and retention
- Object storage setup
- Cache layer (Redis/Memcached)

SECURITY LAYER:
- IAM roles and policies
- Security groups and firewall rules
- Secrets management (Vault / AWS Secrets Manager / other)
- SSL/TLS certificate management
- WAF configuration

CI/CD PIPELINE:
- Build pipeline configuration
- Deployment strategy (blue/green / canary / rolling)
- Environment promotion (dev → staging → production)
- Rollback procedure

MONITORING AND ALERTING:
- Metrics to collect
- Logging architecture
- Alerting thresholds and escalation
- Dashboard structure
- On-call runbook template

COST OPTIMISATION:
- Estimated monthly cost breakdown
- Reserved instance / committed use recommendations
- Spot/preemptible instance opportunities
- Resource tagging strategy

INFRASTRUCTURE AS CODE:
- Terraform module structure for this setup
- Key resource definitions
- Variable and environment management