How to properly propagate gRPC errors Spring-boot - spring-boot

Question

I have been following this article.
I am trying to handle gRPC errors gracefully within Spring-boot application, the main goal is to be able to get the error status in the gRPC client.
Following the article above, I am stuck on adding the interceptor for the exceptions. How do I do this in Spring-boot app? Through #Configuration ?
Or in general, how do you accomplish getting a proper error message through the client of a gRPC call?

Answer 1

You can use the interceptor while creation the Server, see its Github code.
Server server = ServerBuilder
.forPort(8080)
.addService(new GreetingService())
.intercept(new ExceptionHandler())
.build();
You could also switch to Lognet's Spring Boot gRPC lib to use #GRpcGlobalInterceptor.
To use other components in your interceptor declare it as #Component.

Answer 2

You can simplify the error handling if you can convert your gRPC application as Spring Boot using yidongnan/grpc-spring-boot-starter, then you can write #GrpcAdvice, similar to Spring Boot #ControllerAdvice as
#GrpcAdvice
public class ExceptionHandler {
#GrpcExceptionHandler(ResourceNotFoundException.class)
public StatusRuntimeException handleResourceNotFoundException(ResourceNotFoundException cause) {
var errorMetaData = cause.getErrorMetaData();
var errorInfo =
ErrorInfo.newBuilder()
.setReason("Resource not found")
.setDomain("Product")
.putAllMetadata(errorMetaData)
.build();
var status =
com.google.rpc.Status.newBuilder()
.setCode(Code.NOT_FOUND.getNumber())
.setMessage("Resource not found")
.addDetails(Any.pack(errorInfo))
.build();
return StatusProto.toStatusRuntimeException(status);
}
}
On the client-side, you can catch this exception and unpack the registerUserResponse as: as
} catch (StatusRuntimeException error) {
com.google.rpc.Status status = io.grpc.protobuf.StatusProto.fromThrowable(error);
RegisterUserResponse registerUserResponse = null;
for (Any any : status.getDetailsList()) {
if (!any.is(RegisterUserResponse.class)) {
continue;
}
registerUserResponse = any.unpack(ErrorInfo.class);
}
log.info(" Error while calling product service, reason {} ", registerUserResponse.getValidationErrorsList());
//Other action
}
I have written a detailed post about gRPC error handling - Getting Error Handling right in gRPC