OpenTelemetry: Respect provided TracingPolicy in VertxTracer implementations

[calohmn]

Description

When using the quarkus-opentelemetry extension, there currently seems to be no direct way to switch off certain kinds of instrumentation. For example, the Vert.x event bus instrumentation might produce traces that are not needed in certain applications and just produce noise there.

Reading the Vert.x OpenTelemetry documentation, the assumption would be, that the solution here is to just set the TracingPolicy.IGNORE policy on the Vert.x event bus DeliveryOptions.

But this doesn't work with the Quarkus VertxTracer implementations. There, the TracingPolicy parameter is getting ignored (in contrast to the Vert.x OpenTelemetryTracer implementation).

Another example would be HTTP server/client instrumention, where also the TracingPolicy can be set in the client/server options. Being able to use TracingPolicy.IGNORE there would for example make it easier to migrate applications already having a (manual) HTTP request instrumentation. (Letting the HttpInstrumenterVertxTracer traces be discarded by means of a custom Sampler implementation looks like an inferior workaround.)

Implementation ideas

Skip request processing in the Quarkus VertxTracer implementations for requests with TracingPolicy.IGNORE (as done in the Vert.x OpenTelemetryTracer).

[quarkus-bot]

/cc @Ladicek, @radcortez

[tmihalac]

Will have a look

[gsmet]

@calohmn could you give a bit more details about what you're trying to achieve and doesn't work? @tmihalac worked on a fix but he has a hard time figuring out how to reproduce your initial problem and make sure it's fixed.

[radcortez]

Vert.x provides a way to set a TracingPolicy, which can be set to disable to not generate traces. At the moment, setting the value has no effect, since we ignore it. To reproduce it, we just need to set the TracingPolicy on the Vert.x client.

[calohmn]

Here is an example for sending a vert.x event bus message for which no trace should be created:

        final var deliveryOptions = new io.vertx.core.eventbus.DeliveryOptions();
        deliveryOptions.setTracingPolicy(TracingPolicy.IGNORE);
        vertx.eventBus().request(address, message, deliveryOptions);

Example for creating a vert.x HTTP server for which no HTTP request traces shall be created:

        final var httpServerOptions = new io.vertx.core.http.HttpServerOptions();
        httpServerOptions.setTracingPolicy(TracingPolicy.IGNORE);
        // ...
        vertx.createHttpServer(httpServerOptions);

In both cases, setting the tracing policy has no effect.