Custom Instrumentation

On this page you will learn how to manually propagate trace information into and out of your Unreal Engine game.

Continuing a trace from an upstream service requires using ContinueTrace(), which will create a transaction context with the provided sentry-trace header. This transaction starts with the transaction context will contain everything needed to continue the trace.

// Get incoming tracing information
const FString inTrace = ...
TArray<FString>() inBaggage = ...

USentryTransactionContext* transactionContext =
    SentrySubsystem->ContinueTrace(inTrace, inBaggage);

USentryTransaction* transaction =
    SentrySubsystem->StartTransactionWithContext(transactionContext);

To obtain trace header from a transaction or span, use GetTrace(). Pass the returned value to the downstream service. If communication happens over HTTP, we recommend you attach this header to the outgoing HTTP request.

The format of the sentry-trace header should follow the one defined in the telemetry docs. It should consist of a 32 character hexadecimal string for the traceId, followed by a 16 character hexadecimal string for the spanId and an optional single character for the sampled flag. If the given string doesn't match this format, the update is ignored and the values in the transaction context will remain unchanged.