How to add custom attributes to http auto instrumentation?

[klippx]

In the code where metrics are recorded https://github.com/open-telemetry/opentelemetry-js/blob/main/experimental/packages/opentelemetry-instrumentation-http/src/http.ts#L814-L820 the metricAttributes are coming from these two internal functions

• getOutgoingRequestMetricAttributesOnResponse
• getOutgoingRequestMetricAttributes

And there is no way to add your own attributes. For us it would be nice if there was a request hook to inject our own attributes, such as "podRole" which can be "stable" or "canary", and actually change during life cycle of pod, so doing something at initialization is not good.

Is there a deliberate reason why the metric attributes are not exposed for being extended by the user? Or am I just missing how it is done? Thankful for your help and feedback! 🙇

[shirhuang]

Hey, also looking for this functionality. Would be extremely useful if we could customize these attributes to suit our use cases.

[IvanKuzyshyn]

Hey, it is something I need as well. I was playing around with HttpInstrumentation and ExpressInstrumentation to be able to add as well but no luck so far.

[klippx]

There is a PR open and it is in review! #4108

[klippx]

We decided to solve this in otel config instead

otel-config.yaml

    processors:
      attributes/extra:
        actions:
        - key: role
          value: ${env:ROLE}
          action: insert

[s0]

I came across this issue when trying to add some additional attributes across all our metrics in some of my own services, and found it quite surprising that it wasn't supported by default in the Node.js SDK.

The approach I ultimately ended up taking was to require that any additional custom attributes were defined in the resource, and then allowing the exporters to be extended with functionality that would copy over specific attributes from the resources as specified, see full implementation here: #5253

const openTelemetrySdk = new NodeSDK({
  resource: new resources.Resource({
    [ATTR_SERVICE_NAME]: "test-otel-app",
    "deployment.environment.name": "production",
  }),
  metricReader: new PeriodicExportingMetricReader({
    exporter: extendExporterWithResourceAttributes(
      new ConsoleMetricExporter(),
      new Set(["deployment.environment.name", "process.pid"])
    ),
  }),
  instrumentations: getNodeAutoInstrumentations(),
});