Micrometer Tracing doesn't work with @GrpcClient injection in constructors

[artsidorenko]

The context

I was trying to setup observability for application, that use both GrpcServer and GrpcClient.

The bug

It seems that configuration order of micrometer tracing breaks when I add @GrpcClient like ctor parameter for my service, for example:

@Service
class MyService(
    @GrpcClient("my-client")
    private val myClient: OtherServiceGrpcKt.OtherServiceCoroutineStub
) {...}

1. The ObservationRegistry, needed to configure tracing interceptors is noOp, so traces don't work.

2. Everything works fine if I add @GrpcClient as lateinit property to my service and do not use ctor injection.

3. Also works if I add Configuration with @GrpcClientBean and inject client beans without @GrpcClient. (btw, it seems that @dependsOn on config with client beans is necessary, otherwise spring fails to find these beans)

4. And also (that is strange) works if I exclude GrpcClientMicrometerAutoConfiguration:

spring:
  autoconfigure:
    exclude: net.devh.boot.grpc.client.autoconfigure.GrpcClientMicrometerTraceAutoConfiguration

and copy-paste source code of this class to my own code)

Stacktrace and logs
There are tons of WARNs like:
trationDelegate$BeanPostProcessorChecker : Bean 'net.devh.boot.grpc.client.autoconfigure.GrpcClientAutoConfiguration' of type [net.devh.boot.grpc.client.autoconfigure.GrpcClientAutoConfiguration] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying). Is this bean getting eagerly injected into a currently created BeanPostProcessor [grpcClientBeanPostProcessor]? Check the corresponding BeanPostProcessor declaration and its dependencies.

These WARNs are absent in 2) and 3).

Steps to Reproduce

Steps to reproduce the behavior:

1. Create class via the @GrpcClient injected in ctor.
2. Expose some endpoint like hello and try to log traceIds there
3. (*) Try to add logging via ObservationHandler and see that your handler is not registered (and ObservationRegistry is noop as well).

The application's environment

Which versions do you use?

• Spring (boot): 3.3.0
• grpc-java: 1.64.0
• grpc-kotlin-stub: 1.4.1
• grpc-spring-boot-starter: 3.1.0.RELEASE

Additional context

I see that @GrpcClient constructor injection is experimental (as said in javadoc). Hope this issue helps you somehow