The incident: The founder of Crate, a new API gateway designed to catch traffic anomalies, discovered a critical frontend bug the hard way. An expired authentication token triggered a retry loop that hammered their production API with 401 errors for 30 seconds. Their own monitoring system caught it: a 1200% spike in error rates from a single IP.
What went wrong: The frontend lacked proper error boundary logic. Instead of redirecting to login on a 401 response, a race condition in the data-fetching layer caused the dashboard to immediately retry the failed request. With an invalid token, each retry failed, creating a tight loop. The developer only noticed because their phone buzzed with an alert from their own product.
Why this matters: This is a textbook example of client-side retry storms, the kind that turn legitimate traffic into self-inflicted denial of service. The pattern shows up in production more often than vendors admit. Expired tokens, network hiccups, or backend timeouts can all trigger aggressive retry logic if frontends don't implement exponential backoff or circuit breakers.
The fix: A strict check in the API interceptor now halts all outgoing requests immediately upon receiving a 401, forcing a hard redirect to the login page. The patch shipped before the product reached customers.
Enterprise context: API gateways provide rate limiting and token quotas, but they can't prevent poorly designed client behavior from amplifying load. This is where load testing with tools like k6 becomes critical. Testing scenarios should include expired credentials, network delays, and partial failures to catch retry logic before production.
The broader pattern: AWS Shield Standard handles Layer 3/4 DDoS attacks, but application-layer issues like retry storms require different defenses: proper error handling, progressive backoff, and monitoring that distinguishes user spikes from bugs. The incident reinforces why chaos engineering matters, and why operators should test their own systems under realistic failure conditions.
The takeaway: Dogfooding caught a bug that unit tests missed. The real test isn't simulating failure, it's using your own product when you're tired and your token expires on a Monday night.