Dynamic & Global resource attributes in metrics

[aggelako]

I am currently looking for a way to add tags to all reported metrics whose values are calculated on runtime and change during the lifetime of the application.
I could do this by adding it "manually" to all my custom metrics, but then metrics reported by other libraries (process.runtime.. etc) would not have this information.
Is there a good way for me to assign such tags globally on the application level?
Thank you!

[cijothomas]

Unfortunately, no. Dynamic enrichment for Metrics is not supported. (There were some spec discussions around it, but nothing got added to spec, and hence nothing got added to the implementations either)

[aggelako]

Ok, in that case is there a good way to conditionally export metrics based on some condition that you evaluate on runtime?

[cijothomas]

None readily available. (in general, there aren't much ability to dynamic enrich or filter metrics - similar capabilities exist for Traces and Logs via processor, but that is not available for Metrics yet). A lot of users do these filtering out of process, like in the Collector.

[aggelako]

What about implementing Custom Exporters / Extending existing ones? Any examples/suggestions with that?

[cijothomas]

If you write custom ones, then yes it is possible.

https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#metricfilter
This is an experimental spec which is probably what you are looking for - it is not implemented in this repo, so a good option is to open an issue to add support for this to the official sdk itself, and then leverage it.