Why this matters
Reliable backend systems keep core user flows working even when dependencies and traffic misbehave.
How to practice
Practice protecting capacity, preserving correctness, and recovering with evidence.
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Learning objectives
- Choose when to open, half-open, and close a circuit breaker.
- Design fallbacks that preserve business correctness.
- Combine timeouts, bounded retries, jitter, and bulkheads to reduce blast radius.
- Choose high-signal telemetry for common backend incidents.
- Use metrics, logs, traces, deploy markers, and request IDs together.
- Distinguish actionable alerts from noisy operational trivia.
Common mistakes to avoid
- Using very long timeouts that hold threads and amplify outages.
- Counting expected 4xx validation errors as dependency-health failures.
- Retrying without jitter, budgets, or idempotency.
- Serving stale data for correctness-critical decisions such as inventory or payments.
- Relying only on average latency while p95 or p99 users suffer.
- Diving into random logs before scoping by service, route, deploy, or request id.
Games for Production Reliability
Start with the first game, then use local review history to revisit missed decisions.
Reliability Intermediate
Diagnose dependency failures and choose circuit breaker, timeout, fallback, retry, half-open, and bulkhead strategies that reduce blast radius.
- Time
- 6-9 minutes
- Concept
- Circuit breakers, timeouts, retries, fallbacks, and dependency isolation
- Production Reliability
- resilience
- circuit breaker
- timeouts
Play Circuit Breaker Clinic Reliability Intermediate
Triage production incidents by choosing useful metrics, logs, traces, queue signals, database evidence, request ids, and alerting strategies.
- Time
- 6-9 minutes
- Concept
- Production observability, incident triage, metrics, logs, traces, and alerts
- Production Reliability
- observability
- incidents
- metrics
Play Observability Incident Triage Queues Intermediate
Tune workers, retries, and dead-letter behavior while jobs move through an async queue with failures and poison messages.
- Time
- 7-11 minutes
- Concept
- Async jobs, retries, visibility timeout, and dead-letter queues
- Production Reliability
- queues
- retries
- dead-letter queue
Play Message Queue Simulator Scaling Intermediate
Route simulated traffic across backend servers using round robin, weighted round robin, least connections, and random strategies.
- Time
- 6-10 minutes
- Concept
- Load balancing strategies
- Production Reliability
- load balancing
- scaling
- latency
Play Load Balancer Challenge