Return traceId in header response.

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

[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

[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.