There are several projects that leverage eBPF for automatic instrumentation[1].

How accurate and useful these are vs. doing this manually will depend on the use case, but I reckon the automatic approach gets you most of the way there, and you can add the missing traces yourself, so if nothing else it saves a lot of work.

[1]: https://ebpf.io/applications/

Yes, OTel has autoinstrumentation libraries for some language that can pick up a fair amount by default. Though it's unlikely that that would ever be sufficient, it's a nice start.

For Java: https://opentelemetry.io/docs/instrumentation/java/automatic...

Sure, and a lot of tools will do this in one way or another. Either instrument code directly or provide annotations/macros to trace a specific method (something like tokio-tracing in the Rust ecosystem).

However, tracing literally every method call would probably be prohibitively expensive so typically you have either:

1. Instrumentation with "understands" common frameworks/libraries and knows what to instrument (eg request handlers in web frameworks)

2. Full opt-in. They make it easy to add a trace for a method invocation with a simple annotation but nothing gets instrumented by default

Yes, and itel has instrumentation libraries which do this.

However, no automatic instrumentation can do everything for you; it can't know what are all the interesting properties or things to add as attributes. But adding tracing automatically to SQL clients, web frameworks etc is very valuable