How to Propagate Trace Context Across Go Services

Go does not natively propagate trace context across services; you must use an OpenTelemetry-compatible library like go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp to inject and extract context headers. Install the library and wrap your HTTP handlers and clients to automatically handle trace propagation via W3C Trace Context headers.

go get go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp

1. Import the otelhttp package in your server and client code.
2. Wrap your HTTP server handler with otelhttp.NewHandler to extract incoming trace context.
3. Wrap your HTTP client with otelhttp.NewTransport to inject trace context into outgoing requests.
4. Ensure both services use the same OpenTelemetry exporter to visualize the distributed trace.

Trace context propagation lets you track a single request as it moves through multiple Go services, like following a package through different delivery hubs. You need a shared library to attach a unique ID to the request headers so every service knows it's part of the same journey. Without this, you only see isolated logs instead of a complete picture of the user's request flow.