Observability for a Multi-Tenant GraphQL Gateway at Scale

Session description

Viaduct, Airbnb's unified data access layer, hosts over 1.5M lines of application code from 500+ tenants, with 200+ changes merged daily—all operating as a single service. At this scale, enabling teams to independently monitor and troubleshoot their code is essential. This talk describes how we approach observability with multitenancy at the core: - Establishing clear ownership of modules and attributing metrics, spans, and errors to those owners - Providing alerts and dashboards at multiple levels: system, operation, tenant, and field - Enabling schema-driven alerting, where tenants declaratively specify monitoring requirements directly in the schema and the platform implements them automatically - Using execution traces to visualize query execution and core-tenant interactions, tackling challenges like: - Representing batched dataloader calls (where N field requests become 1 RPC) - Instrumenting downstream service clients across all data-fetching code - Managing observability costs via selective sampling and cardinality-aware metrics Our goal: empower tenants to manage their portion of Viaduct as a standalone service—without bottlenecking on the platform team.