same connection usage in grpc-pass in nginx

[rajatgoyal123]

I am trying to set-up nginx reverse proxy server with dynamic upstream
configuration. The upstream servers are grpc servers, so running over
HTTP2.

Since http2 uses multiplexing and grpc supports bi-directional streaming,
can nginx be configured in below way :

a) Every upstream server on start-up will add itself to upstream servers by
calling nginx /api and creates a http2 connection with nginx.

b) Every grpc client when calls grpc API ( via nginx), nginx does grpc_pass
to any of upstream server.

Ask is : For every request in step-b, can nginx, while doing grpc_pass to
upstream server, use the same http2 connection established in step-a ? Is
such configuration possible in nginx ?

When I tested with keepalive 1; in upstream group, I can see it is creating
a new connection once for grpc_pass and using the same ( keepalive = 1), but
it is not using the connection created in step-a.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,292024,292024#msg-292024