request authorization with grpc (failure status code)

[bmacphee]

I appreciate the suggestion but it doesn't look like this is possible to
solve with these modules.  The authentication part happens as a sub-request,
and the response provided by sub request influences how the gRPC part is
handled at the top level.  Unless I can figure out some way to pass
variables from the sub request and handle things differently... I don't
know.

If I return 200, the request proceeds as if it were authorized.  This is
bad.

If I return 401 and try to set the headers/trailers, I don't think it
affects the top level request/response.  I always get grpc.CANCELLED at the
client.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,284718,284876#msg-284876