We Know Before it Breaks: Observability-Driven Development

When stakeholders push for faster growth (new markets, new features, newly modernized stack) your engineering model has to change too. At FitnessPassport, the shift from offshore waterfall delivery to an in-house team meant rebuilding not just services, but confidence: legacy systems with weak logging and little visibility made it hard to know whether changes were working and impossible to spot issues before users did. In this talk, Director of Engineering Rob Mitchell will share how FitnessPassport adopted Datadog and used structured logs, metrics, and traces to tighten feedback loops. The team also leaned on Real User Monitoring (RUM) to see customer journeys and connect performance regressions to specific releases and services. You’ll see how correlating signals from backend services through frontend user experience can quickly take you from “something feels off” to actionable answers. You’ll leave with a practical playbook for modernizing a mixed legacy/service architecture while using observability to move from “react and explain” to “detect and fix” before anyone else can even notice.