[JavaAgent] Autoconfigure customizer for metric exporter in pull-based model, E.g., Prometheus, for all (custom and autogenerated) metrics.

Discussed in https://github.com/open-telemetry/opentelemetry-java/discussions/5163

^{Originally posted by lokeshmavale February 1, 2023}
Hi Team,
I have requirement to send metrics in OTLP & Prometheus format. While sending metric I want to enrich the attributes for all the metrics (custom and autogenerated).

With Auto Configure SPI, I was able to override metrics using autoConfiguration.addMetricExporterCustomizer(this::configureSdkMetricExporterProvider);

I have observed that, this exporter only has access to OTLP (push based) exporter.
How can I override Prometheus exporter without creating all new Prometheus server and registering it with auto agent using autoConfiguration.addMeterProviderCustomizer(). ?

Do we support pull based model exporter override via auto configuration?

Thanks,
Lokesh

Start with the JavaAgent auto-configuration SPI paths using addMetricExporterCustomizer and addMeterProviderCustomizer, then compare the existing OTLP exporter customization with the Prometheus pull-based exporter. Review the linked discussion and determine the supported customization point for custom and autogenerated metrics; done means the intended behavior and scope are implemented or clearly documented.