Designing Resilient APIs

Why Resilience Matters

Modern distributed systems fail in partial, creative ways. Network partitions, slow dependencies, and unexpected payload spikes all conspire to erode reliability.

Core Mitigations

• Circuit breakers isolate persistent downstream failures.
• Bulkheads prevent one noisy tenant from starving others.
• Timeouts & deadlines cap resource lock.
• Exponential backoff with jitter reduces thundering herds.

Example Pseudo Flow

call = withTimeout(200ms) {
  breaker.protect { client.get("/inventory") }
}
if call.failed && call.retryable {
  scheduleRetry(backoff.next())
}

Observability Hooks

Instrument at fan-out points: latency histograms, error ratios, saturation signals.

Checklist

1. Define SLOs first.
2. Add structured error taxonomy.
3. Simulate dependency slowness weekly.
4. Track retry amplification factor.

Ship small, measure, refine.