Add REST client headers as attributes to OpenTelemetry span for REST call

[svifred]

I would like to add attributes, specifically client request and response headers, to the OpenTelemetry span for each REST call. For the OpenTelemetry Java agent instrumentation, I would take advantage of the configuration parameters

otel.instrumentation.http.client.capture-request-headers
otel.instrumentation.http.client.capture-response-headers

but I suspect the Quarkus instrumentation does not provide an implementation of these, as an application.properties with

quarkus.otel.instrumentation.http.client.capture-request-headers=x-request-header
quarkus.otel.instrumentation.http.client.capture-response-headers=x-response-header

results in

WARN Unrecognized configuration key "quarkus.otel.instrumentation.http.client.capture-response-headers" was provided; it will be ignored; verify that the dependency extension for this configuration is set or that you did not make a typo
WARN Unrecognized configuration key "quarkus.otel.instrumentation.http.client.capture-request-headers" was provided; it will be ignored; verify that the dependency extension for this configuration is set or that you did not make a typo

I have tried implementing a ClientResponseFilter utilizing Span.current(), but attributes set on this span is found not on the span for the REST client call, but on the parent span. When adapting the implementation to leverage the Context added as a property on the request by the Quarkus instrumentation OpenTelemetryClientFilter, the context is null, which I suspect is due to the filters immediate closure of the scope and removal of the context from as a request property.

Am I on the right track here, when I suspect an extension of Quarkus' OpenTelemetryClientFilter is necessary? Or am I missing an obvious, maybe even existing, way to add client headers to the span of the REST client calls?

[quarkus-bot[bot]]

/cc @cescoffier (rest-client), @geoand (rest-client)

[geoand]

cc @brunobat

[brunobat]

That is a feature that was never implemented of the REST client implementations. @svifred can you please create an issue with from this discussion?

Th implementation should be straight forward.
We need to create the new properties to control the feature and add attributes to the span in this class:

quarkus/extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/intrumentation/restclient/OpenTelemetryClientFilter.java

Line 44 in 6ccff48

public class OpenTelemetryClientFilter implements ClientRequestFilter, ClientResponseFilter {

and this one as well:

quarkus/extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/intrumentation/resteasy/OpenTelemetryClassicServerFilter.java

Line 21 in e559cbd

public class OpenTelemetryClassicServerFilter implements ContainerRequestFilter {

[svifred]

@brunobat Here we go: Improve OpenTelemetry instrumentation to support adding REST client headers to span for REST call.