Use Patch to Scale clusterapi nodepools to avoid modification conflicts

Issue: #7872
Signed-off-by: Florian Ströger <[email protected]>

Author: Preisschild

cluster-autoscaler/cloudprovider/clusterapi/clusterapi_controller_test.go

@@ -18,7 +18,9 @@ package clusterapi
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"k8s.io/apimachinery/pkg/types"
 	"math/rand"
 	"path"
 	"reflect"
@@ -251,6 +253,39 @@ func mustCreateTestController(t testing.TB, testConfigs ...*testConfig) (*machin
 			}
 
 			return true, s, nil
+		case "patch":
+			action, ok := action.(clientgotesting.PatchAction)
+			if !ok {
+				return true, nil, fmt.Errorf("failed to convert Action to PatchAction: %T", action)
+			}
+
+			pt := action.GetPatchType()
+			if pt != types.MergePatchType {
+				return true, nil, fmt.Errorf("unexpected patch type: expected = %s, got = %s", types.MergePatchType, pt)
+			}
+
+			var scale autoscalingv1.Scale
+			err := json.Unmarshal(action.GetPatch(), &scale)
+			if err != nil {
+				return true, nil, fmt.Errorf("couldn't unmarshal patch: %w", err)
+			}
+
+			_, err = dynamicClientset.Resource(gvr).Namespace(action.GetNamespace()).Patch(context.TODO(), action.GetName(), pt, action.GetPatch(), metav1.PatchOptions{})
+			if err != nil {
+				return true, nil, err
+			}
+
+			newReplicas := scale.Spec.Replicas
+
+			return true, &autoscalingv1.Scale{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      action.GetName(),
+					Namespace: action.GetNamespace(),
+				},
+				Spec: autoscalingv1.ScaleSpec{
+					Replicas: newReplicas,
+				},
+			}, nil
 		default:
 			return true, nil, fmt.Errorf("unknown verb: %v", action.GetVerb())
 		}

cluster-autoscaler/cloudprovider/clusterapi/clusterapi_unstructured.go

@@ -18,18 +18,21 @@ package clusterapi
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"path"
 	"strings"
 	"time"
 
 	"github.com/pkg/errors"
+	autoscalingv1 "k8s.io/api/autoscaling/v1"
 	apiv1 "k8s.io/api/core/v1"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/validation"
 	klog "k8s.io/klog/v2"
 )
@@ -118,17 +121,18 @@ func (r unstructuredScalableResource) SetSize(nreplicas int) error {
 		return err
 	}
 
-	s, err := r.controller.managementScaleClient.Scales(r.Namespace()).Get(context.TODO(), gvr.GroupResource(), r.Name(), metav1.GetOptions{})
-	if err != nil {
-		return err
+	spec := autoscalingv1.Scale{
+		Spec: autoscalingv1.ScaleSpec{
+			Replicas: int32(nreplicas),
+		},
 	}
 
-	if s == nil {
-		return fmt.Errorf("unknown %s %s/%s", r.Kind(), r.Namespace(), r.Name())
+	patch, err := json.Marshal(spec)
+	if err != nil {
+		return fmt.Errorf("could not marshal json patch for scaling: %w", err)
 	}
 
-	s.Spec.Replicas = int32(nreplicas)
-	_, updateErr := r.controller.managementScaleClient.Scales(r.Namespace()).Update(context.TODO(), gvr.GroupResource(), s, metav1.UpdateOptions{})
+	_, updateErr := r.controller.managementScaleClient.Scales(r.Namespace()).Patch(context.TODO(), gvr, r.Name(), types.MergePatchType, patch, metav1.PatchOptions{})
 
 	if updateErr == nil {
 		updateErr = unstructured.SetNestedField(r.unstructured.UnstructuredContent(), int64(nreplicas), "spec", "replicas")