How to set up a GCP LoadBalancer for mixed HTTPS and gRPC traffic

Question

I am trying to make sense of the GCP LoadBalancer for the use case of mixed HTTPS and gRPC backend. The LoadBalancer documentation seems to indicate that you can/should use the HTTP(S) LoadBalancer, as that "includes HTTP/2". For backend services I appear to be able to specify a named "grpc" port and set it to be number 7000, but if I use the gcloud command to view my backend services:

gcloud compute backend-services list --format=json

My service is shown to use portName "grpc" (correct) with port "80" (incorrect). This even though I was prompted that the instance group had named ports, and I could (and did) choose "grpc:7000".

On the frontend side, I can only select ports 80 and 8080 for HTTP, or 443 for HTTPS. No mention of HTTP/2, but I guess "HTTPS includes HTTP/2".

Am I right in that I cannot use the layer 7 LoadBalancer at all for my scenario? The documentation is not very explicit on ports, and if I search the Web for gRPC I get loads of stories on LoadBalancing Kubernetes-hosted apps.

Answer 1

In order to use gRPC you need to use HTTP/2

To use gRPC with your Google Cloud Platform applications, you must proxy requests end-to-end over HTTP/2. To do this with an HTTP(S) load balancer:

Configure an HTTPS load balancer. Enable HTTP/2 as the protocol from the load balancer to the backends.

HTTP/2 and HTTPS are not one and the same, however H2 (HTTPS/2) can only work over HTTPS. But by default H2 is not enabled you need to enable it.

To use gRPC with your Google Cloud Platform applications, you must proxy requests end-to-end over HTTP/2. To do this with an HTTP(S) load balancer:

Configure an HTTPS load balancer. Enable HTTP/2 as the protocol from the load balancer to the backends.

See: https://cloud.google.com/load-balancing/docs/https/ for further information.