desiredIstio: Enable GIE if InferencePool found

Configure the Istio control-plane to enable Gateway API Inference
Extension (GIE) if the InferencePool CRD from GIE exists on the cluster.

Conditionally set one new environment variable in the Istio CR:

    ENABLE_GATEWAY_API_INFERENCE_EXTENSION

This commit resolves NE-2104.

https://issues.redhat.com/browse/NE-2104

* pkg/operator/controller/gatewayclass/controller.go
(inferencepoolCrdName, inferencepoolExperimentalCrdName): New consts.
(NewUnmanaged): Watch customresourcedefinitions, with a predicate on the
InferencePool CRD, in order to reconcile the Istio CR when the
InferencePool CRD is created or deleted.
* pkg/operator/controller/gatewayclass/istio.go (ensureIstio): Use the
new inferencepoolCrdExists helper to check whether the InferencePool CRD
exists, and pass a flag to desiredIstio when the CRD is present.
(inferencepoolCrdExists): New helper.  Using the new crdExists helper,
check whether the InferencePool CRD exists in the
inference.networking.k8s.io or inference.networking.x-k8s.io API groups.
(crdExists): New helper.
(desiredIstio): Add a Boolean parameter, and set the environment
variable when the argument is true.

Author: Miciah

pkg/operator/controller/gatewayclass/controller.go

@@ -15,6 +15,7 @@ import (
 
 	gatewayapiv1 "sigs.k8s.io/gateway-api/apis/v1"
 
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
@@ -31,6 +32,13 @@ import (
 
 const (
 	controllerName = "gatewayclass_controller"
+
+	// inferencepoolCrdName is the name of the InferencePool CRD from
+	// Gateway API Inference Extension.
+	inferencepoolCrdName = "inferencepools.inference.networking.k8s.io"
+	// inferencepoolExperimentalCrdName is the name of the experimental
+	// (alpha version) InferencePool CRD.
+	inferencepoolExperimentalCrdName = "inferencepools.inference.networking.x-k8s.io"
 )
 
 var log = logf.Logger.WithName(controllerName)
@@ -92,6 +100,20 @@ func NewUnmanaged(mgr manager.Manager, config Config) (controller.Controller, er
 		return nil, err
 	}
 
+	// Watch for the InferencePool CRD to determine whether to enable
+	// Gateway API Inference Extension (GIE) on the Istio control-plane.
+	isInferencepoolCrd := predicate.NewPredicateFuncs(func(o client.Object) bool {
+		switch o.GetName() {
+		case inferencepoolCrdName, inferencepoolExperimentalCrdName:
+			return true
+		default:
+			return false
+		}
+	})
+	if err := c.Watch(source.Kind[client.Object](operatorCache, &apiextensionsv1.CustomResourceDefinition{}, reconciler.enqueueRequestForSomeGatewayClass(), isInferencepoolCrd)); err != nil {
+		return nil, err
+	}
+
 	gatewayClassController = c
 	return c, nil
 }

pkg/operator/controller/gatewayclass/istio.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/openshift/cluster-ingress-operator/pkg/operator/controller"
 
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
@@ -38,7 +39,13 @@ func (r *reconciler) ensureIstio(ctx context.Context, gatewayclass *gatewayapiv1
 		Name:       gatewayclass.Name,
 		UID:        gatewayclass.UID,
 	}
-	desired := desiredIstio(name, ownerRef)
+
+	enableInferenceExtension, err := r.inferencepoolCrdExists(ctx)
+	if err != nil {
+		return have, current, err
+	}
+
+	desired := desiredIstio(name, ownerRef, enableInferenceExtension)
 
 	switch {
 	case !have:
@@ -56,8 +63,40 @@ func (r *reconciler) ensureIstio(ctx context.Context, gatewayclass *gatewayapiv1
 	return true, current, nil
 }
 
+// inferencepoolCrdExists returns a Boolean value indicating whether the
+// InferencePool CRD exists under the inference.networking.k8s.io or
+// inference.networking.x-k8s.io API group.
+func (r *reconciler) inferencepoolCrdExists(ctx context.Context) (bool, error) {
+	if v, err := r.crdExists(ctx, inferencepoolCrdName); err != nil {
+		return false, err
+	} else if v {
+		return true, nil
+	}
+
+	if v, err := r.crdExists(ctx, inferencepoolExperimentalCrdName); err != nil {
+		return false, err
+	} else if v {
+		return true, nil
+	}
+
+	return false, nil
+}
+
+// crdExists returns a Boolean value indicating whether the named CRD exists.
+func (r *reconciler) crdExists(ctx context.Context, crdName string) (bool, error) {
+	namespacedName := types.NamespacedName{Name: crdName}
+	var crd apiextensionsv1.CustomResourceDefinition
+	if err := r.cache.Get(ctx, namespacedName, &crd); err != nil {
+		if errors.IsNotFound(err) {
+			return false, nil
+		}
+		return false, fmt.Errorf("failed to get CRD %s: %w", crdName, err)
+	}
+	return true, nil
+}
+
 // desiredIstio returns the desired Istio CR.
-func desiredIstio(name types.NamespacedName, ownerRef metav1.OwnerReference) *sailv1.Istio {
+func desiredIstio(name types.NamespacedName, ownerRef metav1.OwnerReference, enableInferenceExtension bool) *sailv1.Istio {
 	pilotContainerEnv := map[string]string{
 		// Enable Gateway API.
 		"PILOT_ENABLE_GATEWAY_API": "true",
@@ -106,6 +145,9 @@ func desiredIstio(name types.NamespacedName, ownerRef metav1.OwnerReference) *sa
 		// service annotations.
 		"PILOT_ENABLE_GATEWAY_API_COPY_LABELS_ANNOTATIONS": "false",
 	}
+	if enableInferenceExtension {
+		pilotContainerEnv["ENABLE_GATEWAY_API_INFERENCE_EXTENSION"] = "true"
+	}
 	return &sailv1.Istio{
 		ObjectMeta: metav1.ObjectMeta{
 			Namespace:       name.Namespace,