When fetching the pod data for a known core Kind, use a typed client …

…request instead of Unstructured (kedacore#1457)

* When fetching the pod data for a known core Kind, use a typed client request instead of Unstructured. This allows those requests to hit the informer cache while Unstructured gets cannot.

If controller-runtime adds support for reading Unstructured gets from the cache, this could be reverted in the future. This also adds the permissions required for setting up watches.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Fix controller-gen syntax.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Update changelog.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Replace reflect magic with a direct implementation for Deployment and StatefulSet.

These are the only two core types which can be scaled anyway and this code is much less likely to break at runtime in unexpected ways.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Only request cache permissions for Deployments and StatefulSets.

These should be the only two types that are needed with it, so minimal permissions are nice.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

CHANGELOG.md

@@ -31,6 +31,7 @@
 - Optimize Kafka scaler's `getLagForPartition` function. ([#1464](https://github.com/kedacore/keda/pull/1464))
 - Reduce unnecessary /scale requests from ScaledObject controller ([#1453](https://github.com/kedacore/keda/pull/1453))
 - Add support for the WATCH_NAMESPACE environment variable to the operator ([#1474](https://github.com/kedacore/keda/pull/1474))
+- Improve performance when fetching pod information ([#1457](https://github.com/kedacore/keda/pull/1457))
 
 
 ### Breaking Changes

config/rbac/role.yaml

@@ -37,6 +37,14 @@ rules:
   - '*/scale'
   verbs:
   - '*'
+- apiGroups:
+  - apps
+  resources:
+  - deployments
+  - statefulsets
+  verbs:
+  - list
+  - watch
 - apiGroups:
   - autoscaling
   resources:

controllers/scaledobject_controller.go

@@ -38,6 +38,7 @@ import (
 // +kubebuilder:rbac:groups="",resources=pods;services;services;secrets;external,verbs=get;list;watch
 // +kubebuilder:rbac:groups="*",resources="*/scale",verbs="*"
 // +kubebuilder:rbac:groups="*",resources="*",verbs=get
+// +kubebuilder:rbac:groups="apps",resources=deployments;statefulsets,verbs=list;watch
 
 // ScaledObjectReconciler reconciles a ScaledObject object
 type ScaledObjectReconciler struct {

pkg/scaling/scale_handler.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/go-logr/logr"
+	appsv1 "k8s.io/api/apps/v1"
 	"k8s.io/api/autoscaling/v2beta2"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -373,28 +374,51 @@ func (h *scaleHandler) buildScalers(withTriggers *kedav1alpha1.WithTriggers, pod
 func (h *scaleHandler) getPods(scalableObject interface{}) (*corev1.PodTemplateSpec, string, error) {
 	switch obj := scalableObject.(type) {
 	case *kedav1alpha1.ScaledObject:
-		unstruct := &unstructured.Unstructured{}
-		unstruct.SetGroupVersionKind(obj.Status.ScaleTargetGVKR.GroupVersionKind())
-		if err := h.client.Get(context.TODO(), client.ObjectKey{Namespace: obj.Namespace, Name: obj.Spec.ScaleTargetRef.Name}, unstruct); err != nil {
-			// resource doesn't exist
-			h.logger.Error(err, "Target resource doesn't exist", "resource", obj.Status.ScaleTargetGVKR.GVKString(), "name", obj.Spec.ScaleTargetRef.Name)
-			return nil, "", err
-		}
-
-		withPods := &duckv1.WithPod{}
-		if err := duck.FromUnstructured(unstruct, withPods); err != nil {
-			h.logger.Error(err, "Cannot convert unstructured into PodSpecable Duck-type", "object", unstruct)
+		// Try to get a real object instance for better cache usage, but fall back to an Unstructured if needed.
+		podTemplateSpec := corev1.PodTemplateSpec{}
+		gvk := obj.Status.ScaleTargetGVKR.GroupVersionKind()
+		objKey := client.ObjectKey{Namespace: obj.Namespace, Name: obj.Status.ScaleTargetGVKR.Resource}
+		switch {
+		// For core types, use a typed client so we get an informer-cache-backed Get to reduce API load.
+		case gvk.Group == "apps" && gvk.Kind == "Deployment":
+			deployment := &appsv1.Deployment{}
+			if err := h.client.Get(context.TODO(), objKey, deployment); err != nil {
+				// resource doesn't exist
+				h.logger.Error(err, "Target deployment doesn't exist", "resource", gvk.String(), "name", objKey.Name)
+				return nil, "", err
+			}
+			podTemplateSpec.ObjectMeta = deployment.ObjectMeta
+			podTemplateSpec.Spec = deployment.Spec.Template.Spec
+		case gvk.Group == "apps" && gvk.Kind == "StatefulSet":
+			statefulSet := &appsv1.StatefulSet{}
+			if err := h.client.Get(context.TODO(), objKey, statefulSet); err != nil {
+				// resource doesn't exist
+				h.logger.Error(err, "Target deployment doesn't exist", "resource", gvk.String(), "name", objKey.Name)
+				return nil, "", err
+			}
+			podTemplateSpec.ObjectMeta = statefulSet.ObjectMeta
+			podTemplateSpec.Spec = statefulSet.Spec.Template.Spec
+		default:
+			unstruct := &unstructured.Unstructured{}
+			unstruct.SetGroupVersionKind(gvk)
+			if err := h.client.Get(context.TODO(), objKey, unstruct); err != nil {
+				// resource doesn't exist
+				h.logger.Error(err, "Target resource doesn't exist", "resource", gvk.String(), "name", objKey.Name)
+				return nil, "", err
+			}
+			withPods := &duckv1.WithPod{}
+			if err := duck.FromUnstructured(unstruct, withPods); err != nil {
+				h.logger.Error(err, "Cannot convert Unstructured into PodSpecable Duck-type", "object", unstruct)
+			}
+			podTemplateSpec.ObjectMeta = withPods.ObjectMeta
+			podTemplateSpec.Spec = withPods.Spec.Template.Spec
 		}
 
-		if withPods.Spec.Template.Spec.Containers == nil {
-			h.logger.V(1).Info("There aren't any containers found in the ScaleTarget, therefore it is no possible to inject environment properties", "resource", obj.Status.ScaleTargetGVKR.GVKString(), "name", obj.Spec.ScaleTargetRef.Name)
+		if podTemplateSpec.Spec.Containers == nil || len(podTemplateSpec.Spec.Containers) == 0 {
+			h.logger.V(1).Info("There aren't any containers found in the ScaleTarget, therefore it is no possible to inject environment properties", "resource", gvk.String(), "name", obj.Spec.ScaleTargetRef.Name)
 			return nil, "", nil
 		}
 
-		podTemplateSpec := corev1.PodTemplateSpec{
-			ObjectMeta: withPods.ObjectMeta,
-			Spec:       withPods.Spec.Template.Spec,
-		}
 		return &podTemplateSpec, obj.Spec.ScaleTargetRef.EnvSourceContainerName, nil
 	case *kedav1alpha1.ScaledJob:
 		return &obj.Spec.JobTargetRef.Template, obj.Spec.EnvSourceContainerName, nil