123 lines
4.8 KiB
Markdown
123 lines
4.8 KiB
Markdown
# Incident Response Examples
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Real-world production incident examples demonstrating systematic incident response, root cause analysis, mitigation strategies, and blameless postmortems.
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## Available Examples
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### SEV1: Critical Database Outage
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**File**: [sev1-critical-database-outage.md](sev1-critical-database-outage.md)
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Complete database failure causing total service outage:
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- **Incident**: PostgreSQL primary failure, 100% error rate
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- **Impact**: All services down, $50K revenue loss/hour
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- **Root Cause**: Disk full on primary, replication lag spike
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- **Resolution**: Promoted replica, cleared disk space, restored service
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- **MTTR**: 45 minutes (detection → full recovery)
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- **Prevention**: Disk monitoring alerts, automatic disk cleanup, replica promotion automation
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**Key Learnings**:
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- Importance of replica promotion runbooks
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- Disk space monitoring thresholds
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- Automated failover procedures
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---
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### SEV2: API Performance Degradation
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**File**: [sev2-api-performance-degradation.md](sev2-api-performance-degradation.md)
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Gradual performance degradation due to memory leak:
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- **Incident**: API p95 latency 200ms → 5000ms over 2 hours
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- **Impact**: 30% of users affected, slow page loads
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- **Root Cause**: Memory leak in worker process, OOM killing workers
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- **Resolution**: Identified leak with heap snapshot, deployed fix, restarted workers
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- **MTTR**: 3 hours (detection → permanent fix)
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- **Prevention**: Memory profiling in CI/CD, heap snapshot automation, worker restart automation
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**Key Learnings**:
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- Early detection through gradual alerts
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- Heap snapshot analysis for memory leaks
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- Temporary mitigation (worker restarts) vs permanent fix
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---
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### SEV3: Feature Flag Misconfiguration
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**File**: [sev3-feature-flag-misconfiguration.md](sev3-feature-flag-misconfiguration.md)
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Feature flag enabled for wrong audience causing confusion:
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- **Incident**: Experimental feature shown to 20% of production users
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- **Impact**: 200 support tickets, user confusion, no revenue impact
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- **Root Cause**: Feature flag percentage set to 20% instead of 0%
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- **Resolution**: Disabled flag, sent customer communication, updated flag process
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- **MTTR**: 30 minutes (detection → resolution)
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- **Prevention**: Feature flag code review, staging validation, gradual rollout process
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**Key Learnings**:
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- Feature flag validation before production
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- Importance of clear documentation
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- Quick rollback procedures
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---
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### Distributed Tracing Investigation
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**File**: [distributed-tracing-investigation.md](distributed-tracing-investigation.md)
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Using Jaeger distributed tracing to find microservice bottleneck:
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- **Incident**: Checkout API slow (3s p95), unclear which service
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- **Investigation**: Used Jaeger to trace request flow across 7 microservices
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- **Root Cause**: Payment service calling external API synchronously (2.8s)
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- **Resolution**: Moved external API call to async background job
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- **Impact**: p95 latency 3000ms → 150ms (95% faster)
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**Key Learnings**:
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- Power of distributed tracing for microservices
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- Synchronous external dependencies are dangerous
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- Background jobs for non-critical operations
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### Cascade Failure Prevention
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**File**: [cascade-failure-prevention.md](cascade-failure-prevention.md)
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Preventing cascade failure through circuit breakers and bulkheads:
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- **Incident**: Auth service down, caused all dependent services to fail
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- **Impact**: Complete outage instead of graceful degradation
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- **Root Cause**: No circuit breakers, all services retrying auth indefinitely
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- **Resolution**: Implemented circuit breakers, bulkhead isolation, fallback logic
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- **Prevention**: Circuit breaker pattern, timeout configuration, graceful degradation
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**Key Learnings**:
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- Circuit breakers prevent cascade failures
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- Bulkhead isolation limits blast radius
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- Fallback logic enables graceful degradation
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---
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## Learning Outcomes
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After studying these examples, you will understand:
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1. **Incident Classification**: How to assess severity (SEV1-SEV4) based on impact
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2. **Incident Command**: Role of IC, communication protocols, timeline management
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3. **Root Cause Analysis**: 5 Whys, timeline reconstruction, data-driven investigation
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4. **Mitigation Strategies**: Immediate actions, temporary fixes, permanent solutions
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5. **Blameless Postmortems**: Focus on systems not people, actionable items, continuous improvement
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6. **Communication**: Internal updates, external communications, executive briefings
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7. **Prevention**: Monitoring improvements, runbook automation, architectural changes
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---
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## Related Documentation
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- **Reference**: [Reference Index](../reference/INDEX.md) - Severity matrix, communication templates, RCA techniques
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- **Templates**: [Templates Index](../templates/INDEX.md) - Incident timeline, postmortem, runbook templates
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- **Main Agent**: [incident-responder.md](../incident-responder.md) - Incident responder agent
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---
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Return to [main agent](../incident-responder.md)
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