How to Build a Zero-Downtime Cache Invalidation Pipeline Using Webhooks

Cache invalidation in high-throughput systems is prone to failure when TTL values are either too short, causing database overload, or too long, resulting in stale data being served. A more reliable approach uses event-driven invalidation, where database mutations trigger webhook-based purge requests across all edge nodes. Instead of targeting individual URLs, surrogate key tags are attached to HTTP responses, allowing an edge proxy to evict all related cached entries simultaneously when a tag is purged. A resilient webhook dispatcher with exponential backoff retries ensures purge requests are reliably delivered even under transient failures. This architecture achieves global cache eviction in 6–12 milliseconds while preventing thundering herd issues through request coalescing at the origin.