When you set quarkus.grpc.server.use-separate-server=false, Quarkus supports multiple authentication mechanisms as documented here https://quarkus.io/guides/grpc-service-implementation#overview-of-supported-authentication-mechanisms. In regards to your TenantConfigResolver bean, gRPC is build on top of HTTP/2, therefore you don't need to (almost) change anything on your resolver. It should work out of the box. gRPC metadata are implemented using HTTP/2 headers, so try inspecting your headers.