otel_graphql

OpenTelemetry instrumentation for the gql_link chain used by package:graphql and package:graphql_flutter. Built on the Dartastic OpenTelemetry SDK.

Insert one Link at the head of your chain and every GraphQL operation emits a span with the operation type, name, and (opt-in) the printed document.

final link = Link.from([
  OTelGraphqlLink(),
  HttpLink('https://api.example.com/graphql'),
]);
final client = GraphQLClient(link: link, cache: GraphQLCache());

Works for both pure-Dart graphql apps (servers, CLIs) and Flutter apps that use graphql_flutter. Flutter apps may prefer otel_graphql_flutter (the matching overlay) to wire graphql_flutter in one step.

Why

GraphQL operations are coarser than HTTP requests — one POST /graphql can be any of hundreds of operations the front end issues. If you only have HTTP spans, every span has the same name and you can't compare latency across operations. This Link gives you one span per operation name, so a span-by-name view in your tracing backend slices cleanly by GraphQL endpoint.

The integration is opt-in: the OTel SDK does not depend on gql_link or graphql. Add this package only when you want it.

Span shape

Attribute	Source	When set
graphql.operation.type	query / mutation / subscription	when the document specifies one
graphql.operation.name	Operation.operationName	when present (anonymous operations don't set it)
graphql.document	printNode(operation.document) (clipped)	only when recordDocument: true

• Span name: <type> <name> (e.g. query GetUser), falling back to the operation type alone for anonymous operations, or graphql if even that is unknown.
• Span kind: default INTERNAL. The actual network call is usually wrapped by the underlying HTTP / WebSocket Link's own instrumentation — that produces a CLIENT span as a child of this one.
• Span status: Error if the response carries GraphQL errors (Response.errors) or the underlying stream throws, otherwise unset.

Lifecycle

The Link emits a span when an operation enters, and ends it when the response stream closes:

• Query / mutation: single-emission stream — span ends right after the response is yielded.
• Subscription: multi-emission stream — span ends when the consumer cancels or the server closes the stream.

GraphQL errors inside a response (partial failures) flip the span status to Error on first occurrence but the stream keeps flowing — the trace still sees the rest of the data path.

Variables are never captured

There is deliberately no option to record GraphQL variables. Variables routinely carry PII and secrets — emails, passwords, auth tokens, user ids — so variable capture is off by design, not merely off by default. If you need a specific, known-safe value on the span, add it yourself from your own code where you can see what it is.

The one opt-in is recordDocument (default false), which records the document text (the operation shape, with variable references like $id, not values). Even that stays off by default because documents can leak schema details.

Configuration

Constructor arg	Default	Effect
tracer	OTel.tracerProvider().getTracer('otel_graphql')	The tracer that emits the spans.
recordDocument	false	Capture the pretty-printed GraphQL document as graphql.document. Off because documents can leak schema details and variable shapes.
documentMaxLength	1024	Cap on graphql.document when recording is enabled.

Caveats

• Place the OTel link first in the chain so its span encloses whatever auth / retry / HTTP links do downstream.
• Variable values are never captured — only the document text (and only when explicitly opted in). This is intentional: variables are the most reliable place for user data to live in a GraphQL request.
• The link calls OTel.tracerProvider().getTracer(...) in its constructor — OTel.initialize() must have run first.

License

Apache 2.0 — see LICENSE.