Part 9
2 chapters
Observability & the Gateway
Trace and measure resolvers, and compose several subgraphs behind one federated gateway.
Chapter 19
Observability
Telemetry for an API with one endpoint: OpenTelemetry on both stacks, a trace joined to the caller's with a span per resolver and per source call, errors by code and deprecated-field usage as metrics, span metrics from Tempo, log records found by trace id, and what to leave out of all of it.
Chapter 20
Federation & schema composition
One graph owned by several teams: the tracking view split into a cargo subgraph and a handling subgraph on both stacks, entities and references, batched entity resolution, composition as a failing build step, a query plan counted from the subgraphs' logs, and two cross-wired Hive gateways that serve the canonical contract.