Infrastructure Design

Purpose

Design the infrastructure architecture including cloud services, containerization, networking, and deployment topology to support application requirements.

When to Use

• Initial infrastructure design
• Cloud provider selection
• Scaling architecture
• Cost optimization

Prerequisites

• Application architecture defined
• NFRs (especially scalability)
• Budget constraints
• Team DevOps capabilities

Process

Step 1: Define Infrastructure Requirements

From NFRs, determine:
- Compute needs (CPU, memory)
- Storage needs (type, size)
- Network needs (bandwidth, latency)
- Availability requirements (SLA)
- Geographic distribution
- Compliance requirements (data residency)

Step 2: Select Cloud Provider

Evaluation criteria:
- Service availability
- Pricing model
- Team familiarity
- Compliance certifications
- Regional presence
- Managed service quality

Step 3: Design Compute Architecture

Options:
- VMs: Full control, more management
- Containers: Portable, efficient
- Serverless: Pay-per-use, limited control
- Managed services: Less control, less ops

For each tier:
- Web tier
- Application tier
- Database tier
- Background workers

Step 4: Design Networking

Network components:
- VPC/Virtual Network
- Subnets (public/private)
- Load balancers
- CDN for static assets
- DNS configuration
- Firewall rules

Step 5: Create Infrastructure Diagram

Document:
- All components
- Network topology
- Data flow
- Failover paths
- External integrations

Inputs

Input	Type	Required	Description
application_architecture	Markdown	Yes	App design
nfr_matrix	Markdown	Yes	Scale requirements
budget	JSON	Optional	Cost constraints

Outputs

Output	Type	Description
infrastructure_design.md	Markdown	Complete design
infrastructure_diagram	Image/Mermaid	Visual topology
cost_estimate.md	Markdown	Expected costs

StudyAbroad-Specific Considerations

• GDPR: EU data residency for EU users
• Peak load: Application deadline periods
• Document storage: S3 with CDN
• Database: Managed PostgreSQL for reliability

Integration Points

• DevOps Agent: Implementation
• Security Agent: Network security review
• Operations Agent: Monitoring setup

Examples

Infrastructure Design - StudyAbroad-v1

Cloud Provider: AWS (EU-WEST-1 primary for GDPR)

Architecture:
┌─────────────────────────────────────────────────────────┐
│                    CloudFront CDN                        │
│                 (Static assets, caching)                 │
└─────────────────────────────────────────────────────────┘
                           │
                           ▼
┌─────────────────────────────────────────────────────────┐
│              Application Load Balancer                   │
│                    (HTTPS only)                          │
└─────────────────────────────────────────────────────────┘
                           │
                           ▼
┌─────────────────────────────────────────────────────────┐
│                    ECS Fargate                           │
│     ┌─────────────┐  ┌─────────────┐  ┌─────────────┐   │
│     │  API (x3)   │  │  API (x3)   │  │ Worker (x2) │   │
│     └─────────────┘  └─────────────┘  └─────────────┘   │
└─────────────────────────────────────────────────────────┘
                           │
            ┌──────────────┼──────────────┐
            ▼              ▼              ▼
     ┌──────────┐   ┌──────────┐   ┌──────────┐
     │   RDS    │   │ElastiCache│  │    S3    │
     │PostgreSQL│   │  Redis    │   │Documents │
     │ (Multi-AZ)│   │          │   │          │
     └──────────┘   └──────────┘   └──────────┘

Environments:
- Production: Full redundancy
- Staging: Reduced capacity (same architecture)
- Development: Minimal (single instances)

Cost Estimate (Monthly):
- Compute (ECS): $200
- Database (RDS): $150
- Cache (Redis): $50
- Storage (S3): $30
- Network (ALB, CDN): $50
- Total: ~$480/month (staging adds ~$150)

Validation

• Meets availability requirements
• Scales to NFR targets
• Within budget constraints
• GDPR compliance addressed
• Diagram is complete and accurate