Systems Architect

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name: Systems Architect description: Design infrastructure, networks, and cloud systems with integration, reliability, and security patterns. metadata: {"clawdbot":{"emoji":"🌐","os":["linux","darwin","win32"]}}

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Systems Architecture Rules

Infrastructure Design

Design for failure at every layer — hardware fails, networks partition, regions go down

Redundancy costs money, downtime costs more — calculate acceptable risk

Prefer managed services for undifferentiated work — run less, build more

Infrastructure as code from day one — manual changes drift and break

Immutable infrastructure beats patching — replace, don't repair

Cloud Architecture

Multi-AZ minimum, multi-region for critical systems — availability zones fail together sometimes

Right-size first, auto-scale second — baseline must be correct

Reserved capacity for steady load, spot/preemptible for bursts — cost optimization requires planning

Egress costs add up — keep traffic within regions when possible

Cloud vendor lock-in is real — abstract where escape matters, accept where it doesn't

Networking

Private subnets for workloads, public only for load balancers — minimize attack surface

VPC peering and transit gateways for multi-account — plan topology before scaling

DNS for service discovery — hardcoded IPs break migrations

Zero trust: authenticate and encrypt internal traffic — perimeter security isn't enough

Network segmentation limits blast radius — flat networks let attackers roam

Integration Patterns

APIs for synchronous, queues for asynchronous — match pattern to requirements

Event-driven for loose coupling — producers don't know consumers

Service mesh for complex microservices — observability and security at network layer

Rate limiting and backpressure protect systems — don't let slow consumers crash fast producers

Dead letter queues for failed messages — don't lose data, process later

Reliability

Define SLOs before building — what does "up" mean for this system?

Error budgets allow controlled risk — 99.9% means 8 hours downtime per year is acceptable

Blast radius reduction: cell-based architecture — limit how many users one failure affects

Chaos engineering in staging first — break things intentionally before production breaks accidentally

Runbooks for every alert — 3 AM isn't debugging time

Disaster Recovery

RTO (recovery time) and RPO (data loss) are business decisions — architect for the requirement

Backups aren't recovery until tested — restore regularly

Hot/warm/cold standby each have trade-offs — cost vs speed of recovery

Cross-region replication for critical data — single region is single point of failure

DR drills reveal real problems — plan meets reality

Security

Defense in depth: multiple barriers — one layer will fail

Least privilege for services too — not just users

Secrets management centralized — no secrets in code, config files, or environment variables in images

Audit logging for compliance and forensics — you'll need it after a breach

Patch aggressively — known vulnerabilities are actively exploited

Monitoring and Observability

Metrics, logs, and traces together — each tells part of the story

Alerting on symptoms, not causes — users down matters, CPU high might not

Dashboards for each service with golden signals — latency, traffic, errors, saturation

Distributed tracing across services — follow requests end to end

Log aggregation with retention policy — balance cost and forensic needs

Capacity Planning

Measure current baseline before projecting — can't scale what you don't measure

Load test to find breaking points — theory differs from reality

Capacity leads demand — scaling takes time, be ahead

Cost modeling for growth scenarios — 10x users is rarely 10x cost

Review quarterly at minimum — patterns change

Migration and Evolution

Strangler fig pattern for legacy replacement — route traffic gradually

Blue-green or canary for infrastructure changes — test in production safely

Database migrations are hardest — plan data migration separately

Rollback plans before rollout — assume failure, prepare for it

Communicate maintenance windows — surprises damage trust