Trailer not set for StatusException returned by GrpcExceptionHandler #332
Description
We use GrpcExceptionHandlers to return StatusExceptions with some additional details like
public @Nullable StatusException handleException(Throwable exception) {
if (!(exception instanceof AccessDeniedException)) {
return null;
}
var status = Status.newBuilder()
.setCode(Code.PERMISSION_DENIED_VALUE)
.setMessage("access denied")
.addDetails(
Any.pack(LocalizedMessage.newBuilder()
.setLocale("de-CH")
.setMessage("Zugriff verweigert")
.build()
)
)
.build();
return StatusProto.toStatusException(status);
}
Unfortunately, this extra information is not rendered as trailer in the gRPC response. It looks like the headers of the returned StatusException is ignored in the interceptCall method of the GrpcExceptionHandlerInterceptor.
@Override
public <ReqT, RespT> Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call, Metadata headers,
ServerCallHandler<ReqT, RespT> next) {
Listener<ReqT> listener;
FallbackHandler fallbackHandler = new FallbackHandler(this.exceptionHandler);
GrpcExceptionHandledServerCall<ReqT, RespT> exceptionHandledServerCall = new GrpcExceptionHandledServerCall<>(
call, fallbackHandler);
try {
listener = next.startCall(exceptionHandledServerCall, headers);
}
catch (Throwable t) {
this.logger.trace("Failed to start exception handler call", t);
StatusException statusEx = fallbackHandler.handleException(t); // <-- this returns the StatusException including additional details
exceptionHandledServerCall.close(statusEx != null ? statusEx.getStatus() : Status.fromThrowable(t),
headers(t)); /// <-- this drops the headers.
return new Listener<>() {
};
}
return new ExceptionHandlerListener<>(listener, exceptionHandledServerCall, fallbackHandler);
}
From my point of view this is a bug and should be fixed. In my expectation the header should be computed based on statusEx if statusEx != null and headers(t) should only be called if statusEx == null.