Distributed Tracing

This document describes how a SDK should propagate information between different services to connect all telemetry (errors, profiles, replays, transaction) from those services into one trace.

For an overview see Distributed Tracing in the product docs.

Sentry uses two containers to hold trace information sentry-trace and baggage.

With these containers you can propagate a trace to a down-stream service. By either

• adding sentry-trace and baggage HTTP headers (when doing outgoing HTTP requests),
• adding sentry-trace and baggage as meta data (when putting tasks into a queue, details are specific to the queue you want to support), or
• setting environment variables (when calling another process). In this case the env variables should be called SENTRY_TRACE and SENTRY_BAGGAGE.

The SDK running in the receiving service needs to make sure to pick up incoming trace information by

• reading sentry-trace and baggage headers for each incoming HTTP request,
• reading sentry-trace and baggage meta data when retrieving an item from a queue, or
• reading the environment variables SENTRY_TRACE and SENTRY_BAGGAGE on start up.

This trace information should be stored in the "propagation context" of the current scope. This makes sure that all telemetry that is emmited from the receiving service to Sentry will include the correct trace information.