Selective Metric Export & Configurable Default Attributes

[polartulip]

What?

Enhance the k6 extension with the following features:

Selective Metric Export – Allow users to specify which k6 metrics should be exported, preventing unnecessary data collection and reducing storage usage.
Configurable Default Attributes – Provide an option to control default attributes, making high-cardinality fields (e.g., URL) opt-in instead of being reported by default.

Why?

Efficiency & Storage Optimization – k6 generates a large number of metrics, many of which may not be required. Limiting exported metrics reduces storage consumption and improves performance.
Better Resource Management – High-cardinality attributes like URLs can cause resource exhaustion and may not always be necessary. Making them opt-in allows users to control data volume more effectively.

[joanlopez]

Hi @polartulip,

Thanks for your feature request.
However, I strongly suspect we won't work on this anytime soon, if ever, because I think that's a common feature request for k6 in general (see #1321 and others), thus wouldn't make sense to fix that kind of common problem in a specific extension like OTEL (this one).

If you're willing to push for that feature, I'd recommend you to leave a 👍🏻 in the aforementioned issue, as well as a comment explaining your concrete needs, if not mentioned in that issue yet. If you look for "filter metrics" in the Issues page, you'll notice that it's a recurrent topic that I hope we can get focused onto it sooner rather than later.

Meanwhile, I've been playing around some ideas at https://github.com/joanlopez/xk6-custosummary, although that one isn't going to be the definitive form because implementing this feature as a extension has many limitations, like not being re-usable for other extensions, I hope it sets the stage for a formal feature in k6 in the near future.

I'm sorry for not being able to bring an immediate solution, but I hope that brings some clarity around the future! 🙇🏻