How to retrieve resource attributes whilst using OpenTelemetry Node.js SDK?

[dayuloli]

How to retrieve resource attributes whilst using OpenTelemetry Node.js SDK?

[pichlermarc]

As of today, the OpenTelemetry API specification does not include a way to retrieve the resource, therefore this is also not exposed in the JavaScript OTel API.

Are you using OTel for logging or some other solution? If you're using OTel, then all logs that are being exported will have the resource added to it.

[pichlermarc]

I am looking at the instrumentation package for Pino and don't see where it is retrieving the resource attributes. In the README.md, it also says it only adds trace_id, span_id, and trace_flags.

A pino logs bridge is not implemented yet, only bunyan has a working logs instrumentation at the moment. One for winston is in the works right now.

Or do you mean using @opentelemetry/api-logs and @opentelemetry/sdk-logs? In that case, I am assuming the LoggerProvider holds a reference to the resource.

Yes, for logging (for instance with bunyan), the resource will be associated with the logs that are being exported via OTLP, as it has a bridge that passes the logs created via bunyan to @opentelemtry/api-logs.

So if I do want to roll my own, I'd have to hold my own reference to the resource, and manually pass that into the SDK as well as to my application.

Also yes. But keep in mind: keeping the resource around and using it in your app goes against the way OTel is supposed to be used. In your app, after setting up in ./instrumentation.js you should only be using the @opentelemetry/api package, and should never reference SDK components like the Resource again. This is set up in this way so that you can make a localized change (in instrumentation.js) once there's an SDK 2.0, while keeping all your application code that depends on the API package which does not significantly change and is planned to stay stable for a much longer time than the SDK would.

To summarize a Resource is intended to be used with OTel SDKs, and any other uses are not something we'd recommend or support.

That being said, all information that's set in the resource can be somewhat easily be recreated by using the resource detectors again that are exported from the @opentelemetry/resouces package (hostDetectorSync, osDetectorSync, envDetectorSync, ...) and merging it together manually using Resource.merge()

[dayuloli]

Are you using OTel for logging or some other solution? If you're using OTel, then all logs that are being exported will have the resource added to it.

We have our own custom logger so can't use one of the ready-made instrumentation packages.

I am looking at the instrumentation package for Pino and don't see where it is retrieving the resource attributes. In the README.md, it also says it only adds trace_id, span_id, and trace_flags.

Or do you mean using @opentelemetry/api-logs and @opentelemetry/sdk-logs? In that case, I am assuming the LoggerProvider holds a reference to the resource. So if I do want to roll my own, I'd have to hold my own reference to the resource, and manually pass that into the SDK as well as to my application.

[dayuloli]

Thanks. I will look at those packages and the Logs Bridge API, thanks for all the tip and pointers!

[sarfarazahmedkl]

        import opentelemetry, * as api from '@opentelemetry/api';
        const tracer = opentelemetry.trace.getTracer(
            'service-name',
            'service-version',
         );
        const span = tracer.startSpan('span-name');
        let activeContext: any = api.propagation.extract(api.context.active(), {});
        let key = api.createContextKey('OpenTelemetry Context Key SPAN')
        let attributeValue = activeContext.getValue(key)?.attributes['attribute-name']

All attributes related to span will be saved to the 'OpenTelemetry Context Key SPAN' context, so we can access attribute value from the app.js file as mentioned above.

[pichlermarc]

        import opentelemetry, * as api from '@opentelemetry/api';
        const tracer = opentelemetry.trace.getTracer(
            'service-name',
            'service-version',
         );
        const span = tracer.startSpan('span-name');
        let activeContext: any = api.propagation.extract(api.context.active(), {});
        let key = api.createContextKey('OpenTelemetry Context Key SPAN')
        let attributeValue = activeContext.getValue(key)?.attributes['attribute-name']

All attributes related to span will be saved to the 'OpenTelemetry Context Key SPAN' context, so we can access attribute value from the app.js file as mentioned above.

context.getValue() returns unknown on purpose. It may be there today but keep in mind that this approach may break at any time without warning in the future.