Reactor status code with ExchangeFilterFunction

[jeanbisutti]

Let' take the following ExchangeFilterFunction in Reactor.

public ExchangeFilterFunction customStatusHandler() {
        return ExchangeFilterFunction.ofResponseProcessor(clientResponse -> {
            if (clientResponse.statusCode().isError()) {
                return clientResponse.createException().flatMap(clientError -> Mono.error(new CustomException(clientError.getResponseBodyAsString())));
            } else {
                return Mono.just(clientResponse);
            }
        });
    }

In case of an HTTP endpoint returning the 500 HTTP status, the following client telemetry is then emitted:

[reactor-http-nio-4] INFO io.opentelemetry.exporter.logging.LoggingSpanExporter - 'POST' : fe51b25aef90ef613b35553d9e8ddc66 985f9d622832cadd CLIENT [tracer: io.opentelemetry.spring-webflux-5.0:2.12.0-alpha] AttributesMap{data={http.request.method=POST, thread.id=67, server.address=localhost, server.port=8081, error.type=app1.CustomException, thread.name=http-nio-8080-exec-3, url.full=http://localhost:8081/test-app2}, capacity=128, totalAddedValues=7}

The instrumentation reflects the behavior of the Mono.error API and the client telemetry does not contain the status code.

It seems fine to me. Do you rather think that there is a bug or limitation and the client telemetry should contain the status code in this case?

Without the ExchangeFilterFunction or if the client response status is not an error:

[reactor-http-nio-2] INFO io.opentelemetry.exporter.logging.LoggingSpanExporter - 'POST' : e9b01c442c1f8ae805a25cbb3a438927 cd9588c7700b062a CLIENT [tracer: io.opentelemetry.spring-webflux-5.0:2.12.0-alpha] AttributesMap{data={server.port=8081, http.request.method=POST, http.response.status_code=500, error.type=500, server.address=localhost, thread.id=64, thread.name=http-nio-8080-exec-1, url.full=http://localhost:8081/test-app2}, capacity=128, totalAddedValues=8}