Using HTTP2 and gRPC - Knative Serving | Serverless | Red Hat OpenShift Service on AWS

OpenShift Serverless supports only insecure or edge-terminated routes. Insecure or edge-terminated routes do not support HTTP2 on Red Hat OpenShift Service on AWS. These routes also do not support gRPC because gRPC is transported by HTTP2. If you use these protocols in your application, you must call the application using the ingress gateway directly. To do this you must find the ingress gateway’s public address and the application’s specific host.

Interacting with a serverless application using HTTP2 and gRPC

This method needs to expose Kourier Gateway using the LoadBalancer service type. You can configure this by adding the following YAML to your KnativeServing custom resource definition (CRD):

...
spec:
  ingress:
    kourier:
      service-type: LoadBalancer
...

Prerequisites

OpenShift Serverless Operator and Knative Serving are installed on your cluster.
Install the OpenShift CLI (oc).
You have created a Knative service.

Procedure

Find the application host. See the instructions in Verifying your serverless application deployment.

Find the ingress gateway’s public address:

$ oc -n knative-serving-ingress get svc kourier

Example output

NAME                   TYPE           CLUSTER-IP      EXTERNAL-IP                                                             PORT(S)                                                                                                                                      AGE
kourier   LoadBalancer   172.30.51.103   a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com   80:31380/TCP,443:31390/TCP   67m

The public address is surfaced in the EXTERNAL-IP field, and in this case is a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com.

Manually set the host header of your HTTP request to the application’s host, but direct the request itself against the public address of the ingress gateway.
```
$ curl -H "Host: hello-default.example.com" a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com
```
Example output
```
Hello Serverless!
```
You can also make a gRPC request by setting the authority to the application’s host, while directing the request against the ingress gateway directly:
```
grpc.Dial(
    "a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com:80",
    grpc.WithAuthority("hello-default.example.com:80"),
    grpc.WithInsecure(),
)
```
Ensure that you append the respective port, 80 by default, to both hosts as shown in the previous example.