Does anyone have experience (good, bad, otherwise) using the gRPC JSON transcoding option for real-world stuff? I'm debating using it (still need REST clients sometimes) but I'm not sure how hacky it is.
They say not to rely on the output being stable, so I would recommend guaranteeing a stable translation yourself for a REST client. You can achieve this by translating from the JSON to your proto or grpc service structure yourself.
Also you should look at Google Artman on github/googleapis as sometimes it felt that defining the REST mappings in Protobuf were lacking some features. Using google artman you kind of mix/match Protobuf with yaml definitions of your service.
We never had to use it, though. It just depends on where you want to put your authentication information. As of today I would probably change my mind and make it explicitly in payload, I.e. Protobuf message and not fiddle with headers any more.