chaos-engineering-resilience

Chaos Engineering & Resilience Testing

<default_to_action> When testing system resilience or injecting failures:

1. DEFINE steady state (normal metrics: error rate, latency, throughput)
2. HYPOTHESIZE system continues in steady state during failure
3. INJECT real-world failures (network, instance, disk, CPU)
4. OBSERVE and measure deviation from steady state
5. FIX weaknesses discovered, document runbooks, repeat

Quick Chaos Steps:

• Start small: Dev → Staging → 1% prod → gradual rollout
• Define clear rollback triggers (error_rate > 5%)
• Measure blast radius, never exceed planned scope
• Document findings → runbooks → improved resilience

Critical Success Factors:

• Controlled experiments with automatic rollback
• Steady state must be measurable
• Start in non-production, graduate to production </default_to_action>

Quick Reference Card

When to Use

• Distributed systems validation
• Disaster recovery testing
• Building confidence in fault tolerance
• Pre-production resilience verification

Failure Types to Inject

Category	Failures	Tools
Network	Latency, packet loss, partition	tc, toxiproxy
Infrastructure	Instance kill, disk failure, CPU	Chaos Monkey
Application	Exceptions, slow responses, leaks	Gremlin, LitmusChaos
Dependencies	Service outage, timeout	WireMock

Blast Radius Progression

Dev (safe) → Staging → 1% prod → 10% → 50% → 100%
     ↓           ↓         ↓        ↓
  Learn      Validate   Careful   Full confidence

Steady State Metrics

Metric	Normal	Alert Threshold
Error rate	< 0.1%	> 1%
p99 latency	< 200ms	> 500ms
Throughput	baseline	-20%

---

Chaos Experiment Structure

// Chaos experiment definition
const experiment = {
  name: 'Database latency injection',
  hypothesis: 'System handles 500ms DB latency gracefully',
  steadyState: {
    errorRate: '< 0.1%',
    p99Latency: '< 300ms'
  },
  method: {
    type: 'network-latency',
    target: 'database',
    delay: '500ms',
    duration: '5m'
  },
  rollback: {
    automatic: true,
    trigger: 'errorRate > 5%'
  }
};