A war story about debugging a critical production issue and the systems we built to prevent it from happening again.
It was 3:17 AM when my phone started buzzing. PagerDuty. The dashboard was red. CPU at 100% across the cluster. Response times through the roof. Customers were tweeting.
I stumbled to my laptop, still half asleep, and started the familiar ritual: check metrics, check logs, check recent deployments.
Nothing obvious. No recent deploys. Traffic was normal. But something was consuming all our resources.
The investigation:
Hour 1: Ruled out the usual suspects—no memory leaks, no runaway queries, no infinite loops in new code.
Hour 2: Noticed a pattern. The spike correlated with a specific type of API request.
Hour 3: Found it. A third-party service we depended on had changed their API response format. Our parsing code was falling into an exponential retry loop.
The fix was simple. The lessons were profound:
1. Always set timeouts and circuit breakers for external dependencies 2. Monitor not just your systems, but your integrations 3. Have runbooks ready for common failure modes 4. Practice incident response before you need it
We shipped the fix by 6 AM. Then we spent the next month building the observability and resilience we should have had from the start.