diegosouzapw Architecture Documentation
Create clear, comprehensive architecture documentation that communicates design decisions and system structure to stakeholders.
When to Use This Skill
- New system design
- Architecture changes
- Team onboarding
- Stakeholder communication
- Technical reviews
- Knowledge transfer
- Compliance requirements
- Decision tracking
Core Concepts
1. Architecture Decision Record (ADR)
# ADR 001: Use PostgreSQL for Primary Database
**Date:** 2024-01-15
**Status:** Accepted
**Deciders:** Tech Lead, Solutions Architect, Backend Team
## Context
Need to select a database for new e-commerce platform. Requirements:
- ACID transactions for order processing
- Complex queries (joins, aggregations)
- Strong consistency
- Support for 100K users initially, 1M within 2 years
## Decision
Use PostgreSQL as primary database.
## Alternatives Considered
**MySQL:**
- ✅ Widely used, good documentation
- ✅ Strong community support
- ❌ Historically weaker for complex queries
- ❌ JSON support not as robust
**MongoDB:**
- ✅ Flexible schema
- ✅ Horizontal scaling
- ❌ No multi-document ACID transactions (at time of decision)
- ❌ Eventual consistency by default
**DynamoDB:**
- ✅ Fully managed, auto-scaling
- ❌ Complex query limitations
- ❌ Vendor lock-in
- ❌ Cost unpredictable at scale
## Rationale
- PostgreSQL offers ACID guarantees needed for financial transactions
- Advanced SQL features (window functions, CTEs) for analytics
- Excellent JSON support for flexible data
- Proven at scale (Instagram, Uber)
- Can add read replicas for scaling
- Strong typing prevents data errors
## Consequences
**Positive:**
- Strong data consistency
- Rich query capabilities
- Battle-tested reliability
- Excellent tooling ecosystem
**Negative:**
- Vertical scaling limits (mitigated with read replicas)
- More complex horizontal sharding (if needed in future)
- Requires DBA expertise for optimization
## Compliance
No specific compliance requirements impacted.
## Notes
Will reassess if we need to shard beyond 10M users.
2. System Architecture Document
# System Architecture: E-Commerce Platform
## Overview
Microservices-based e-commerce platform supporting 1M users with high availability and scalability.
## Architecture Principles
1. Microservices for domain separation
2. API-first design
3. Event-driven communication
4. Cloud-native (AWS)
5. Infrastructure as Code
## System Context (C4 Level 1)
[Diagram showing users, system, external systems]
## Container Diagram (C4 Level 2)
**Frontend:**
- React SPA (S3 + CloudFront)
- Mobile Apps (iOS/Android)
**Backend Services:**
- API Gateway (AWS API Gateway)
- User Service (Node.js, PostgreSQL)
- Product Service (Node.js, PostgreSQL)
- Order Service (Node.js, PostgreSQL)
- Payment Service (Node.js)
- Notification Service (Node.js, SES)
**Data Stores:**
- PostgreSQL (RDS Multi-AZ)
- Redis (ElastiCache)
- S3 (product images)
**Messaging:**
- EventBridge (event bus)
- SQS (queues)
**External:**
- Stripe (payment processing)
- SendGrid (email)
## Technology Stack
**Frontend:**
- React 18
- TypeScript
- Tailwind CSS
**Backend:**
- Node.js 20
- Express.js
- TypeScript
- PostgreSQL 15
- Redis 7
**Infrastructure:**
- AWS (primary cloud)
- Terraform (IaC)
- GitHub Actions (CI/CD)
- DataDog (monitoring)
## Security
- HTTPS only (TLS 1.3)
- JWT authentication
- Role-based access control
- Encryption at rest (AES-256)
- Regular security scans (Snyk, OWASP ZAP)
## Scalability
- Horizontal scaling with Auto Scaling Groups
- Database read replicas
- CDN for static assets
- Redis caching
- Async processing with SQS
## Disaster Recovery
- RPO: 1 hour
- RTO: 4 hours
- Multi-AZ deployment
- Daily database backups
- Cross-region replication for critical data
## Monitoring & Observability
- DataDog APM
- CloudWatch logs
- Custom metrics dashboard
- PagerDuty alerts
Best Practices
- Keep it current - Update with changes
- Multiple views - Different stakeholders need different levels
- Visual diagrams - Architecture diagrams, sequence diagrams
- Decision rationale - Document "why", not just "what"
- ADRs for major decisions - Track decision history
- Living documentation - Evolve with system
- Version control - Track changes over time
- Review regularly - Quarterly architecture reviews
Resources
- C4 Model: https://c4model.com
- ADR Templates: https://adr.github.io
- Structurizr: Architecture diagram tool