Building Resilient Systems

# Building Resilient Systems

Systems fail. Plan for it. Build systems that degrade gracefully and recover quickly.

## Resilience Principles

**Redundancy**

No single points of failure. Multiple instances, multiple zones, multiple regions.

**Graceful Degradation**

When something fails, reduce functionality instead of crashing.

**Fast Recovery**

Detect failures quickly. Recover automatically.

## Patterns for Resilience

**Retry Logic**

Transient failures happen. Retry with exponential backoff.

**Circuit Breaker**

Stop calling failing services. Monitor and auto-reset.

**Timeout**

Don't wait forever. Fail fast with reasonable timeouts.

**Bulkhead**

Isolate resources. Prevent cascade failures.

## Chaos Engineering

**Test Failure Scenarios**

- Kill random instances

- Inject latency

- Simulate network partitions

- Overflow resources

## Monitoring and Alerting

- SLIs and SLOs

- Error budgets

- Incident response plans

- Post-mortem culture

Hope for the best. Plan for the worst.