SERIES 05

Backend Engineering

Production incidents, bottlenecks, and how I verify backend fixes.

EP.01 · The Domino Effect in MQTT Authentication

Devices could not connect to MQTT. Following the request path led me through CPU saturation, database connections, and retries that kept feeding the incident.

EP.02 · The Shard I Cut in June Sent the Bill in October

Device log pages started returning 500. The trail led back to a one-shard decision in June and an `_id` sort in July, both mine. How I connected them, and the step I skipped in September.