For… reasons, I wanted to pre-filter gRPC requests to check for authorization. Authorization is implemented as a ‘micro-service’ and I wanted the authorization server to run in the same process as the gRPC client. TL;DR: Shiju’s “Writing gRPC Interceptors in Go” is great This Stack overflow answer ostensibly for writing unit tests for gRPC got me an in-process server What follows stands on these folks’ shoulders… A key motivator for me to write blog posts is that helps me ensure that I understand things.