Chaos Engineering & Resilience Testing

Core Principle

Systems fail. Build systems that fail gracefully.

Chaos engineering proactively introduces failures to discover weaknesses before they cause outages. Resilience testing validates recovery capabilities.

What is Chaos Engineering?

Chaos Engineering: Experimenting on distributed systems to build confidence in system ability to withstand turbulent conditions.

Principles:

1. Define steady state (normal metrics)
2. Hypothesize steady state continues
3. Introduce real-world failures
4. Try to disprove hypothesis
5. Fix weaknesses, repeat

Types of Failures to Inject

Network Failures

• Latency injection
• Packet loss
• Network partitions
• DNS failures
• Connection timeouts

Infrastructure Failures

• Instance termination
• Disk failures
• CPU exhaustion
• Memory pressure
• Cascading failures

Application Failures

• Exceptions
• Slow responses
• Resource leaks
• Deadlocks

Controlled Experiments

Start small, increase blast radius gradually:

1. Development: Test locally
2. Staging: Test in staging environment
3. Production Canary: 1% of traffic
4. Production Gradual: 10% → 50% → 100%

Netflix Chaos Monkey

Randomly terminates instances:

// Chaos Monkey configuration
{
  "enabled": true,
  "meanTimeBetweenKillsInWorkDays": 2,
  "minTimeBetweenKillsInWorkDays": 1,
  "grouping": "cluster",
  "regions": ["us-east-1"],
  "exceptions": ["production-critical"]
}

With qe-chaos-engineer Agent

// Agent runs controlled chaos experiments
const experiment = await agent.runChaosExperiment({
  target: 'payment-service',
  failure: 'terminate-random-instance',
  blastRadius: '10%',
  duration: '5m',
  steadyStateHypothesis: {
    metric: 'success-rate',
    threshold: 0.99
  }
});

// Verifies:
// - System recovers automatically
// - Error rate stays below threshold
// - No data loss
// - Alerts triggered appropriately

Remember

Break things on purpose to prevent unplanned outages.

• Find weaknesses before users do
• Build confidence in system resilience
• Validate recovery procedures work
• Create runbooks from experiments

With Agents: qe-chaos-engineer automates chaos experiments with blast radius control, automatic rollback, and comprehensive resilience validation.