Datadog processor & exporter export different operation name

[GuillaumeDecMeetsMore]

Hello,

First, thank you for all the work on Otel and Otel-contrib :)

We are having a small issue when integrating the Otel Collector with Datadog. We are trying to use tail-sampling in order to sample all the errors but still use probabilistic sampling for the rest.

We managed to setup everything but it seems we are having a mistmatch between the (correct) operation name parsed by datadog processor and the operation name sent by datadog exporter (for traces).

---

We have this service. The metrics shown are coming from Otel Collector with datadog processor. Here we have realtime.server as the operation name on the top, which I guess is ${appName}.${span.kind} in the NodeJS lib.

That's all good, except that if you look at the details of the resources: we have no traces/spans.
And, if we go to "all traces view" of this service, we see nothing.

But, if we then remove the filter on operationName, then we can see the traces coming in (all errors and a few successes as expected). Looking at those, they seem to have another operation name opentelemetry.server (I suppose this is what is given on the bottom left).

Before, we were sending from the otel library to the DD agent via gRPC. This was working fine and both metrics and traces had realtime.server as the operation name (but, that doesn't allow to do tail sampling at the collector level).

The configuration of the Otel Collector is the following:

receivers:
  otlp:
    protocols:
      grpc:
      http:

processors:
  datadog:
    metrics_exporter: datadog
  batch:
    send_batch_max_size: 100
    send_batch_size: 20
    timeout: 10s
  tail_sampling:
    decision_wait: 15s
    num_traces: 50000
    policies:
      [
        {
          name: randomized-policy,
          type: probabilistic,
          probabilistic: { sampling_percentage: 10 },
        },
        {
          name: latency-policy,
          type: latency,
          latency: { threshold_ms: 5000 },
        },
        {
          name: errors-policy,
          type: status_code,
          status_code: { status_codes: [ERROR] },
        },
      ]

exporters:
  datadog:
    api:
      site: datadoghq.com
      key: ${env:DD_API_KEY}

extensions:
  health_check:

service:
  extensions: [health_check]
  pipelines:
    traces:
      receivers: [otlp]
      processors: [datadog, tail_sampling, batch]
      exporters: [datadog]
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [datadog]
  telemetry:
    logs:
      encoding: "json"

Adding this in the exporter works:

    traces:
      span_name_remappings:
        opentelemetry.server: realtime.server

But I have the feeling it should work without it, so here I am checking if we have missed something 👀

Thanks!