System Architecture · Additional notes
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Mid-level7 min read
Rapid overview
Additional notes
Choosing a System Architecture
- Need fast delivery and strong consistency? Start with a modular monolith.
- Need independent scaling and multi-team ownership? Consider microservices.
- Need streaming or decoupled workflows? Add event-driven messaging.
- Need extensibility for clients/plugins? Use micro-kernel patterns.
- Building a small internal tool? Layered / N-tier is fine.
Comparison Table
| Architecture | Consistency | Scalability | Complexity | Team Size |
|---|
| Modular Monolith | Strong | Limited | Low | Small |
| Microservices | Eventual | High | High | Large |
| Event-Driven | Eventual | High | Medium | Medium+ |
| API Gateway + Microservices | Varies | High | High | Large |
Observability Requirements
Per Architecture Style
| Style | Logging | Tracing | Metrics | Priority |
|---|
| Monolith | Standard | Optional | Basic | Low |
| Microservices | Centralized | Required | Distributed | Critical |
| Event-Driven | Correlation IDs | Required | Queue depth | Critical |
| Tool | Purpose |
|---|
| Serilog + Loki/ELK | Centralized structured logging |
| OpenTelemetry + Jaeger | Distributed tracing |
| Prometheus + Grafana | Metrics and dashboards |
| Health Checks | Liveness, readiness probes |
Security Considerations
OWASP Top 10 for Distributed Systems
| Vulnerability | Mitigation |
|---|
| Broken Access Control | Tenant isolation, RBAC at gateway |
| Injection | Input validation, parameterized queries |
| Insecure Design | Threat modeling, security reviews |
| Security Misconfiguration | Secrets management (Vault) |
| Vulnerable Components | Dependency scanning, updates |
| Authentication Failures | OAuth2/OIDC, MFA |
| Logging Failures | Audit logging, log aggregation |
Multi-Tenant Security Checklist
- [ ] Tenant ID validated on every request
- [ ] Global query filters prevent cross-tenant access
- [ ] Separate encryption keys per tenant (optional)
- [ ] Rate limiting per tenant
- [ ] Audit logging with tenant context
Scalability Patterns
Horizontal Scaling
| Component | Strategy |
|---|
| Stateless Services | Add more instances behind load balancer |
| Database | Read replicas, connection pooling (PgBouncer) |
| Cache | Redis cluster with replication |
| Message Broker | Partitioned queues, consumer groups |
| Storage | S3-compatible distributed storage |
Scaling Checklist
- [ ] Services are stateless
- [ ] Database connections pooled
- [ ] Session state externalized (Redis)
- [ ] Health checks implemented
- [ ] Horizontal Pod Autoscaling configured