Adding request-based tags to url session spans

[SebastianOsinski]

Is your feature request related to a problem? Please describe.

Use case: I would like the span to include additional tag with GraphQL operation name in it.

Right now, when using built-in URLSessionInstrumentation, it is only possible to add static tags to all requests by configuring tags property when enabling tracing. I would like to add tags with dynamic values, depending on what request is being made.
Currently there is no way to access the span created by TracingURLSessionHandler

On Android it is possible to do this by using TracedRequestListener

Describe the solution you'd like

A possibility to define listeners/callbacks for URLSessionInstrumentation which would allow editing the span based on the request. Similar to the Android solution

Describe alternatives you've considered

I thought I could achieve it by accessing Tracer.shared().activeSpan in my implementation of DatadogURLSessionHandler but it is not populated. I also tried to somehow create a span with trace id and span id from URLSessionTaskInterception received in my implementation of DatadogURLSessionHandler but I don't see a way of doing that.

Additional context

Add any other context or screenshots about the feature request here.

[ganeshnj]

Indeed iOS SDK doesn't have similar feature to intercept the span created by the instrumentation.

We can provide something similar here in the form of either delegate or a closure. You can pass this as part of URLSessionInstrumentation.Configuration. Hence, you can callback per enable URLSessionInstrumentation call.

[SebastianOsinski]

@ganeshnj that sounds perfect. Thank you for such swift response!

[ElonPark]

I have the same needs as the current issue

We can provide something similar here in the form of either delegate or a closure. You can pass this as part of
URLSessionInstrumentation.Configuration. Hence, you can callback per enable URLSessionInstrumentation call.

@ganeshnj Can you provide sample code for the method you suggested in your answer?

[ganeshnj]

Like I said, we don't have such capability as of now in the iOS SDK but something we can provide in future.

Thanks for upvoting, it helps us prioritize the issues.

[servercimen]

@ganeshnj @maxep I have the same issue. It's quite limiting to have the graphql traces not contain operation name and operation type (query,mutation or subscription). Even if DataDog won't or can't support building a generic solution to add custom tags, can you add these two tags? I'd consider them essential to do anything useful like generating Datadog Metrics based on the traces. Right now it's not even possible generate a very basic metric to count GraqhQL requests per operation.

[jbluntz]

+1 - this would be really handy! One workaround I've found is to specify the attributes on RUM resources via a RUM.ResourceAttributesProvider:

RUM.enable(
          with: RUM.Configuration(
            applicationID: config.applicationId,
            urlSessionTracking: RUM.Configuration.URLSessionTracking(
                firstPartyHostsTracing: RUM.Configuration.URLSessionTracking.FirstPartyHostsTracing.trace(hosts: config.hosts, sampleRate: config.traceSamplingRate),
                resourceAttributesProvider: { request, response, data, error in
                    //parse request and return map of attributes here
                }
            ),
            trackFrustrations: true,
            trackBackgroundEvents: true
          )
        )

The attributes end up in RUM resources and the corresponding traces.

The big downside to this is that all RUM custom attributes are namespaced under @context.*, making it difficult to align attribute names with other sources and impossible to adhere to OpenTelemetry semantic conventions.