Why Every Production Webhook Endpoint Becomes a Tiny Distributed System

A webhook endpoint may start as a simple Rails controller action, but production requirements quickly layer on complexity including signature verification, background jobs, and retry logic. Security comes first: providers like GitHub and Stripe sign their payloads with HMAC-SHA256, and the raw request body must be verified before any parsing occurs. Duplicate event delivery, out-of-order processing, and concurrent workers introduce the same challenges found in large-scale distributed systems. The article walks through a minimal Rails implementation that handles signature validation using a shared secret and Rails' timing-safe secure_compare. The author argues that a single HTTP webhook endpoint, once hardened for production, mirrors the core concerns of distributed architecture in miniature.