Zero-code instrumentation with ContentProvider

[Doohl]

Thanks to the new OpenTelemetryRumInitializer it's now super easy to initialize OpenTelemetryRum with all the opinionated configs. But it would be nice if there was a true zero code solution for onboarding an existing Android app, like what we have in the backend world for otel today: https://opentelemetry.io/docs/concepts/instrumentation/zero-code/

I think the simplest way to accomplish this is with an Android ContentProvider, so that users can get the SDKs / exporters initialized without writing a single line of code. However, you do need to specify some configs somewhere, like:

• Traces / Logs endpoints for the OtlpHttp*Exporters
• Resource attribute customization
• DiskBuffering / session provider configs

We can either have users provide these via a JSON file that's read as part of the ContentProvider initialization logic, or maybe have them provided via a Gradle plugin like:

openTelemetryRum {
   logsEndpoint = // blah //
   tracesEndpoint = // blah //
}

[fractalwrench]

Jetpack's App Startup library should probably be part of any discussion around this. Initializing a ContentProvider is relatively expensive if every library in an app does it, so the App Startup library effectively takes the performance hit of initializing one ContentProvider and initializes any components that have registered to be started.

Using a ContentProvider/App Startup library is also non-deterministic in when a component gets initialized, at least in terms of API guarantees. From my experience a minority of users want to disable it for this reason, so any solution would need either an opt-in or opt-out.

I definitely agree this functionality would be useful though - perhaps in a separate module that folks could include or exclude depending on the needs of their app.

[bidetofevil]

Seems like a good feature, but given the complications with depending on the startup library, I think it should be an opt-in and in a separate module so this is not a new required dependency for folks who don't want to use it.