feat: Add Prometheus gauges for FeatureStore installation telemetry

infra/feast-operator/cmd/main.go

@@ -49,6 +49,7 @@ import (
 	routev1 "github.com/openshift/api/route/v1"
 
 	"github.com/feast-dev/feast/infra/feast-operator/internal/controller"
+	feastmetrics "github.com/feast-dev/feast/infra/feast-operator/internal/controller/metrics"
 	"github.com/feast-dev/feast/infra/feast-operator/internal/controller/services"
 	// +kubebuilder:scaffold:imports
 )
@@ -95,6 +96,7 @@ func main() {
 	var probeAddr string
 	var secureMetrics bool
 	var enableHTTP2 bool
+	var featureStoreMetrics bool
 	var tlsOpts []func(*tls.Config)
 	flag.StringVar(&metricsAddr, "metrics-bind-address", "0", "The address the metrics endpoint binds to. "+
 		"Use :8443 for HTTPS or :8080 for HTTP, or leave as 0 to disable the metrics service.")
@@ -106,6 +108,9 @@ func main() {
 		"If set, the metrics endpoint is served securely via HTTPS. Use --metrics-secure=false to use HTTP instead.")
 	flag.BoolVar(&enableHTTP2, "enable-http2", false,
 		"If set, HTTP/2 will be enabled for the metrics and webhook servers")
+	flag.BoolVar(&featureStoreMetrics, "feature-store-metrics", true,
+		"Enable Prometheus gauges exposing online/offline store and registry configuration per FeatureStore. "+
+			"Disable with --feature-store-metrics=false.")
 	opts := zap.Options{
 		Development: true,
 	}
@@ -206,9 +211,19 @@ func main() {
 
 	services.SetIsOpenShift(mgr.GetConfig())
 
+	var fsMetrics *feastmetrics.FeatureStoreMetrics
+	if featureStoreMetrics {
+		fsMetrics = feastmetrics.NewFeatureStoreMetrics()
+		fsMetrics.Register()
+		setupLog.Info("FeatureStore installation metrics enabled")
+	} else {
+		setupLog.Info("FeatureStore installation metrics disabled (--feature-store-metrics=false)")
+	}
+
 	if err = (&controller.FeatureStoreReconciler{
-		Client: mgr.GetClient(),
-		Scheme: mgr.GetScheme(),
+		Client:  mgr.GetClient(),
+		Scheme:  mgr.GetScheme(),
+		Metrics: fsMetrics,
 	}).SetupWithManager(mgr); err != nil {
 		setupLog.Error(err, "unable to create controller", "controller", "FeatureStore")
 		os.Exit(1)

infra/feast-operator/go.mod

@@ -15,6 +15,7 @@ require (
 
 require (
 	github.com/prometheus-operator/prometheus-operator/pkg/client v0.83.0
+	github.com/prometheus/client_golang v1.22.0
 	k8s.io/utils v0.0.0-20250502105355-0f33e8f1c979
 )
 
@@ -55,7 +56,6 @@ require (
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/prometheus-operator/prometheus-operator/pkg/apis/monitoring v0.83.0 // indirect
-	github.com/prometheus/client_golang v1.22.0 // indirect
 	github.com/prometheus/client_model v0.6.1 // indirect
 	github.com/prometheus/common v0.62.0 // indirect
 	github.com/prometheus/procfs v0.15.1 // indirect

infra/feast-operator/internal/controller/featurestore_controller.go

@@ -43,6 +43,7 @@ import (
 	feastdevv1 "github.com/feast-dev/feast/infra/feast-operator/api/v1"
 	"github.com/feast-dev/feast/infra/feast-operator/internal/controller/authz"
 	feasthandler "github.com/feast-dev/feast/infra/feast-operator/internal/controller/handler"
+	feastmetrics "github.com/feast-dev/feast/infra/feast-operator/internal/controller/metrics"
 	"github.com/feast-dev/feast/infra/feast-operator/internal/controller/services"
 	routev1 "github.com/openshift/api/route/v1"
 )
@@ -55,7 +56,8 @@ const (
 // FeatureStoreReconciler reconciles a FeatureStore object
 type FeatureStoreReconciler struct {
 	client.Client
-	Scheme *runtime.Scheme
+	Scheme  *runtime.Scheme
+	Metrics *feastmetrics.FeatureStoreMetrics
 }
 
 // +kubebuilder:rbac:groups=feast.dev,resources=featurestores,verbs=get;list;watch;create;update;patch;delete
@@ -87,6 +89,9 @@ func (r *FeatureStoreReconciler) Reconcile(ctx context.Context, req ctrl.Request
 		if apierrors.IsNotFound(err) {
 			// CR deleted since request queued, child objects getting GC'd, no requeue
 			logger.V(1).Info("FeatureStore CR not found, has been deleted")
+			if r.Metrics != nil {
+				r.Metrics.DeleteFeatureStore(req.NamespacedName.Namespace, req.NamespacedName.Name)
+			}
 			// Clean up namespace registry entry even if the CR is not found
 			if err := r.cleanupNamespaceRegistry(ctx, &feastdevv1.FeatureStore{
 				ObjectMeta: metav1.ObjectMeta{
@@ -107,6 +112,9 @@ func (r *FeatureStoreReconciler) Reconcile(ctx context.Context, req ctrl.Request
 	// Handle deletion - clean up namespace registry entry
 	if cr.DeletionTimestamp != nil {
 		logger.Info("FeatureStore is being deleted, cleaning up namespace registry entry")
+		if r.Metrics != nil {
+			r.Metrics.DeleteFeatureStore(cr.Namespace, cr.Name)
+		}
 		if err := r.cleanupNamespaceRegistry(ctx, cr); err != nil {
 			logger.Error(err, "Failed to clean up namespace registry entry")
 			return ctrl.Result{}, err
@@ -115,6 +123,9 @@ func (r *FeatureStoreReconciler) Reconcile(ctx context.Context, req ctrl.Request
 	}
 
 	result, recErr = r.deployFeast(ctx, cr)
+	if recErr == nil && r.Metrics != nil {
+		r.Metrics.RecordFeatureStore(cr)
+	}
 	if cr.DeletionTimestamp == nil && !reflect.DeepEqual(currentStatus, cr.Status) {
 		if err = r.Client.Status().Update(ctx, cr); err != nil {
 			if apierrors.IsConflict(err) {

infra/feast-operator/internal/controller/metrics/metrics.go

@@ -0,0 +1,133 @@
+/*
+Copyright 2026 Feast Community.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package metrics provides a Prometheus info gauge that records the store
+// types configured for each FeatureStore CR (online store, offline store,
+// registry). These operator-level metrics are distinct from the Feast
+// feature-server application metrics (feast_feature_server_*) and are useful
+// for usage telemetry and assessing the impact of removing store type support.
+package metrics
+
+import (
+	feastdevv1 "github.com/feast-dev/feast/infra/feast-operator/api/v1"
+	"github.com/prometheus/client_golang/prometheus"
+	ctrlmetrics "sigs.k8s.io/controller-runtime/pkg/metrics"
+)
+
+const typeNone = "none"
+
+// FeatureStoreMetrics holds the Prometheus GaugeVec for feast-operator
+// installation telemetry.
+type FeatureStoreMetrics struct {
+	FeatureStoreInfo *prometheus.GaugeVec
+}
+
+// NewFeatureStoreMetrics creates a new FeatureStoreMetrics with the GaugeVec
+// initialised but not yet registered. Call Register() before starting the manager.
+func NewFeatureStoreMetrics() *FeatureStoreMetrics {
+	return &FeatureStoreMetrics{
+		FeatureStoreInfo: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Name: "feast_operator_feature_store_info",
+				Help: "Information about a deployed FeatureStore. " +
+					"Value is always 1. Labels carry the configured store types: " +
+					"'online_store_type', 'offline_store_type', and 'registry_type' " +
+					"are set to the persistence type (e.g. redis, snowflake.offline, local) " +
+					"or 'none' when that component is not configured.",
+			},
+			[]string{"namespace", "name", "online_store_type", "offline_store_type", "registry_type"},
+		),
+	}
+}
+
+// Register registers the metric with the controller-runtime metrics registry
+// so it is exposed on the manager's /metrics endpoint.
+func (m *FeatureStoreMetrics) Register() {
+	ctrlmetrics.Registry.MustRegister(m.FeatureStoreInfo)
+}
+
+// RecordFeatureStore updates the gauge for the given FeatureStore using the
+// applied configuration stored in status.Applied (which has operator defaults
+// applied). The previous label set for this FeatureStore is deleted first so
+// that store type changes are reflected cleanly on the next scrape.
+func (m *FeatureStoreMetrics) RecordFeatureStore(fs *feastdevv1.FeatureStore) {
+	svcs := fs.Status.Applied.Services
+	m.FeatureStoreInfo.DeletePartialMatch(prometheus.Labels{
+		"namespace": fs.Namespace,
+		"name":      fs.Name,
+	})
+	m.FeatureStoreInfo.WithLabelValues(
+		fs.Namespace,
+		fs.Name,
+		onlineStoreType(svcs),
+		offlineStoreType(svcs),
+		registryType(svcs),
+	).Set(1)
+}
+
+// DeleteFeatureStore removes the metric label set for the given FeatureStore.
+// Safe to call when the CR has already been deleted from the API server.
+func (m *FeatureStoreMetrics) DeleteFeatureStore(namespace, name string) {
+	m.FeatureStoreInfo.DeletePartialMatch(prometheus.Labels{
+		"namespace": namespace,
+		"name":      name,
+	})
+}
+
+// onlineStoreType returns the online store persistence type or "none".
+func onlineStoreType(svcs *feastdevv1.FeatureStoreServices) string {
+	if svcs == nil || svcs.OnlineStore == nil {
+		return typeNone
+	}
+	if p := svcs.OnlineStore.Persistence; p != nil && p.DBPersistence != nil {
+		return p.DBPersistence.Type
+	}
+	return "file"
+}
+
+// offlineStoreType returns the offline store persistence type or "none".
+func offlineStoreType(svcs *feastdevv1.FeatureStoreServices) string {
+	if svcs == nil || svcs.OfflineStore == nil {
+		return typeNone
+	}
+	if p := svcs.OfflineStore.Persistence; p != nil {
+		if p.DBPersistence != nil {
+			return p.DBPersistence.Type
+		}
+		if p.FilePersistence != nil && p.FilePersistence.Type != "" {
+			return p.FilePersistence.Type
+		}
+	}
+	return "file"
+}
+
+// registryType returns "local", "remote", "remote_feastref", or "none".
+func registryType(svcs *feastdevv1.FeatureStoreServices) string {
+	if svcs == nil || svcs.Registry == nil {
+		return typeNone
+	}
+	switch {
+	case svcs.Registry.Local != nil:
+		return "local"
+	case svcs.Registry.Remote != nil:
+		if svcs.Registry.Remote.FeastRef != nil {
+			return "remote_feastref"
+		}
+		return "remote"
+	default:
+		return typeNone
+	}
+}