Airbnb migrated its observability platform from a vendor-managed service to an in-house solution based on open-source technology. The primary motivation was to reduce costs and gain greater control over data and workflows. The initial migration strategy involved tackling a complex service first, but this proved inefficient. A revised strategy focused on migrating a simpler service to prove feasibility and establish a solid foundation. The new approach prioritized complete migration over immediate query improvements to avoid overwhelming users with too many changes. They built translator tooling to map existing dashboards and alerts to the new system. They focused on migrating query intent instead of direct translations, correcting flawed patterns. Implementing a metadata engine ensured accurate metric typing in the new system. They adopted PromQL, a widely understood query language, and integrated AI-powered tooling to aid in query generation. The migration also enabled the replacement of an outdated alert framework. This comprehensive overhaul led to superior tooling, consistent data, and a significantly improved developer experience.