Modernizing Artifact Storage at Uber

This post details the migration of Uber's artifact storage from a legacy on-premise system to a managed SaaS offering. A key technical contribution is the introduction of an internal proxy layer that uses conditional HTTP requests (If-None-Match, If-Modified-Since) to validate artifact freshness against the SaaS origin, significantly reducing egress costs by over 99% and achieving 99.99% reliability. The proxy maintains an artifact metadata store (MySQL) and serves unchanged artifacts from an internal cache, ensuring correctness through per-request validation rather than time-based cache expiration. The architecture is active-active across two Uber data centers pinned to nearest cloud regions for low latency and includes GeoDNS failover for resilience.