Document GRPC starter + Kafka Stream usage

[jedvardsson]

Hi, I am having problem starting a spring cloud app using this project when no Kafka is available, which is normal in development. The app will hang until KafkaAdminClient times out after 60 s before the app is fully started.

What happens is that the bean grpcInternalConfigurator which is defined as a Consumer<ServerBuilder<?>> seems to request a Kafka Topic. This is because spring cloud streaming treats beans of Consumer, Supplier and Function as part of their messing system.

I am not sure if the intent of GRpcAutoConfiguration is to depend on this feature. From what I can tell it does not look so, however, I am a novice in this area so I could be wrong.

[jvmlet]

GRpcAutoConfiguration doesn't depend on Kafka. I'll check

This is because spring cloud streaming treats beans of Consumer, Supplier and Function as part of their messing system.

If you could provide the project that reproduces the behavior, it would be great.

[jedvardsson]

Great, I'll fix a minimal project to reproduce the issue shortly.

[jedvardsson]

Here is sample project that shows the problem.

https://github.com/jedvardsson/grpc-spring-boot-starter-hangs-waiting-for-kafka-bug

[jvmlet]

Thanks @jedvardsson, I'll have a look

[jvmlet]

@jedvardsson , according to this, we will need to explicitly set the consumer/producer function definitions, no way to mark the Consumer/Produce/Function beans as not eligible for registration.
I'll commit the demo with test for this use case soon

[jvmlet]

@jedvardsson , this is essential if you have more than 1 Consumer/Producer/Function bean.
Demo test is here

[jvmlet]

@jedvardsson ,FYI