Return traceId in header response.

[dcdh]

Description To debug more easily an Ajax request I propose to return the traceId in response header.

Implementation ideas

I've follow this code https://github.com/quarkusio/quarkus/blob/master/extensions/jaeger/runtime/src/main/java/io/quarkus/jaeger/runtime/MDCScope.java

package com.damdamdeo.todo.publicfrontend.interfaces;

import io.jaegertracing.internal.JaegerSpanContext;
import io.opentracing.SpanContext;
import io.opentracing.Tracer;

import javax.inject.Inject;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerResponseContext;
import javax.ws.rs.container.ContainerResponseFilter;
import javax.ws.rs.ext.Provider;
import java.io.IOException;

@Provider
public class TraceIdResponseInjector implements ContainerResponseFilter {

    @Inject
    Tracer tracer;

    private static final String TRACE_ID = "traceId";

    @Override
    public void filter(final ContainerRequestContext requestContext, final ContainerResponseContext responseContext) throws IOException {
        final SpanContext spanContext = tracer.scopeManager().active().span().context();
        if (spanContext instanceof JaegerSpanContext) {
            responseContext.getHeaders().add(TRACE_ID, ((JaegerSpanContext) spanContext).getTraceId());
        }
    }

}

I guess it should be implemented in quarkus-smallrye-opentracing.

Regards,

Damien

[quarkusbot]

/cc @kenfinnigan, @Ladicek

[Ladicek]

I think this makes sense, though there probably should be a configuration switch to turn it off. (I think it's pretty safe to have it on by default, even in production, but some users in highly regulated environments would probably like to turn it off.)

CC @pavolloffay

[kenfinnigan]

I'd prefer it the other way around, off by default except when running with quarkus:dev which enables it.

@dcdh can you elaborate on the use case? Is it purely for testing in development, or some other reason?

[dcdh]

@kenfinnigan I am working for a client for an internal platform compound of several micro-services. We use the Spring Boot + Spring Cloud Sleuth ... stack. Spring Cloud Sleuth add in our response header some data coming from opentracing like x-b3-traceid. It was added to help support team to easier trace the flow of interaction between our multiple micro-services from the frontend. So when we figure out an issue from the front, we take the control of the user's computer and try again displaying the Ajax call and retrieve the x-b3-traceid. Likes this it help use to retrieve directly traces in Zipkin and logs in Kibana. Also it is very useful when you want to debug or do a demo to display all the calls from action as you can easily trace them from front using your browser inspector and zipkin.

[Ladicek]

Tracing is, by definition, meant for production. I just wonder what would happen in case the tracer decides not to sample the trace. I don't know, but I hope that there's a way to detect that and either not include the header in the response at all, or somehow indicate that the trace is not sampled.

[pavolloffay]

This seems like a good feature.

[kenfinnigan]

@dcdh, @Ladicek raised a good point around sampling.

When you're using Spring Cloud Sleuth, do you sample all the requests? What happens if you're not sampling them all?

[pavolloffay]

The IDs should be generated when though the trace is not being sampled. We could propagate the sampling bit also to inform the caller.

[dcdh]

Ok, so I was speaking about b3 propagation. Info about specification can be found here https://github.com/openzipkin/b3-propagation I've tried to implement it using Spring cloud sleuth without success. I need to check how it was done in my job client.

[Ladicek]

The IDs should be generated when though the trace is not being sampled. We could propagate the sampling bit also to inform the caller.

Yea, sorry for not being clear. I understand that each trace has an ID, even if the tracer decides to not sample it. I was just wondering what should we do in such case, or if there's even something we can do.

[Legion2]

For the W3C Trace Context there was a spec added for response headers https://github.com/w3c/trace-context/pull/365, so it should also be added to the W3C propagation.

[melloware]

Yes similar to Spring Boot it should respect incoming HTTP headers for Trace/Span and always put them on the outgoing response. This way you can trace microservice to microservice calls across your organization. This is similar to what Spring Boot Slueth does.

[mfpc]

Could anyone confirm if this is correct, Should I create a PR ?

https://github.com/smallrye/smallrye-opentracing/compare/main...mfpc:smallrye-opentracing:traceID-header-response

[Legion2]

According to this w3c draft the response header should be called traceresponse and not only contain the trace-id.

[juniormichieletto]

Good point @dcdh in this proposal! Actually we are doing this manually in some projects 😅 and it was useful in some moments to use 😃 Also, could be nice the same in "opentelemetry" extension (if is not done at this moment) since the "openttracing" extension is marked to be discontinued.

Ps. I also undestand with you proposal doesn't should not affect any client propagation headers that should keep working as before, respecting the propagation strategy like x-b3, w3 or other. Am I right?

https://quarkus.io/guides/opentracing

[mcruzdev]

Hi @brunobat how are you? Can I get this one... or is there some definitions to get before?

[brunobat]

I'd say, given the discussion, there is no consensus and I don't see this as a priority, for now.

[brunobat]

Let's try to move on with this. @ahreurink Would you like to give it a try to this one? Please mind that:

1. This needs to be activated by a config property
2. Let's try traceresponse and see how it goes. See comments bellow. [EDIT]
3. This needs to be returned both by Resteasy Classic and Ractive

Try first to create the tests to what you expect.

[Legion2]

As mentioned earlier, there is an open W3C draft for a standardized response header https://w3c.github.io/trace-context/#traceresponse-header

[brunobat]

You are right @Legion2. Researched this a bit more and there is no mention of the usage of the traceresponse header in the OTel spec or it's Java implementation. I guess we should align with the W3C spec for the https://w3c.github.io/trace-context/#trace-context-http-response-headers-format and implement what's in there. The implementation could draw inspiration from io.opentelemetry.api.trace.propagation.W3CTraceContextPropagator