What to do with instrumentation-api Config

[trask]

follow-up from open-telemetry/opentelemetry-java#4563 (comment)

some options

• only allow programmatic configuration in library instrumentation for now, and move Config to javaagent-extension-api
• keep Config in instrumentation-api as-is
• move Config to an internal package

(+ maybe renaming Config to InstrumentationConfig to help clarify it's only used for instrumentation configuration and not for sdk configuration)

[mateuszrzeszutek]

• only allow programmatic configuration in library instrumentation for now, and move Config to javaagent-extension-api

That would be my preferred solution (maybe even combined with making InstrumentationConfig internal) if weren't for the fact that we're still using Config internally in the instrumenter API: like here or here.
Maybe we could replace these internal usages with a very simple getSysPropOrEnvVar internal utility method in instrumentation-api? With the exception of the suppression strategy, all other config options are debugging utilities, and I think we don't really need to care about the SPI or file config for these.

[anuragagarwal561994]

@trask how to use and get the configurations within extension InstrumentationModule?

[mateuszrzeszutek]

You can use InstrumentationConfig -- it offers roughly the same functionality as Config, but it's only available in the javaagent instrumentations. It's still in an internal package, so we cannot commit to its stability, but I believe that accessing the configuration in javaagent instrumentations will always be a necessary feature, so I don't think it's ever going away -- we probably might rename it at some point in the future (although we have no such plans right now).

[anuragagarwal561994]

Yes I thought for the same. Just because it had internal packaging I thought if it would be right to use the same.