Use Patch instead of Update in the daemonset_controller when scaling

Signed-off-by: Aurel Canciu <[email protected]>

Author: relu

pkg/canary/daemonset_controller.go

@@ -18,6 +18,7 @@ package canary
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 
 	"go.uber.org/zap"
@@ -26,6 +27,7 @@ import (
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/util/retry"
 
@@ -34,7 +36,7 @@ import (
 )
 
 var (
-	daemonSetScaleDownNodeSelector = map[string]string{"flagger.app/scale-to-zero": "true"}
+	daemonSetScaleDownNodeSelector = map[string]interface{}{"flagger.app/scale-to-zero": "true"}
 )
 
 // DaemonSetController is managing the operations for Kubernetes DaemonSet kind
@@ -54,39 +56,35 @@ func (c *DaemonSetController) ScaleToZero(cd *flaggerv1.Canary) error {
 		return fmt.Errorf("daemonset %s.%s get query error: %w", targetName, cd.Namespace, err)
 	}
 
-	daeCopy := dae.DeepCopy()
-	daeCopy.Spec.Template.Spec.NodeSelector = make(map[string]string,
-		len(dae.Spec.Template.Spec.NodeSelector)+len(daemonSetScaleDownNodeSelector))
-	for k, v := range dae.Spec.Template.Spec.NodeSelector {
-		daeCopy.Spec.Template.Spec.NodeSelector[k] = v
+	patch, err := c.getNodeSelectorPatch(daemonSetScaleDownNodeSelector)
+	if err == nil {
+		_, err = c.kubeClient.AppsV1().DaemonSets(dae.Namespace).Patch(context.TODO(), dae.GetName(), types.StrategicMergePatchType, patch, metav1.PatchOptions{})
 	}
 
-	for k, v := range daemonSetScaleDownNodeSelector {
-		daeCopy.Spec.Template.Spec.NodeSelector[k] = v
-	}
-
-	_, err = c.kubeClient.AppsV1().DaemonSets(dae.Namespace).Update(context.TODO(), daeCopy, metav1.UpdateOptions{})
 	if err != nil {
-		return fmt.Errorf("updating daemonset %s.%s failed: %w", daeCopy.GetName(), daeCopy.Namespace, err)
+		return fmt.Errorf("updating daemonset %s.%s failed: %w", dae.GetName(), dae.Namespace, err)
 	}
 	return nil
 }
 
 func (c *DaemonSetController) ScaleFromZero(cd *flaggerv1.Canary) error {
 	targetName := cd.Spec.TargetRef.Name
-	dep, err := c.kubeClient.AppsV1().DaemonSets(cd.Namespace).Get(context.TODO(), targetName, metav1.GetOptions{})
+	dae, err := c.kubeClient.AppsV1().DaemonSets(cd.Namespace).Get(context.TODO(), targetName, metav1.GetOptions{})
 	if err != nil {
 		return fmt.Errorf("daemonset %s.%s query error: %w", targetName, cd.Namespace, err)
 	}
 
-	depCopy := dep.DeepCopy()
+	nodeSelector := map[string]interface{}{}
 	for k := range daemonSetScaleDownNodeSelector {
-		delete(depCopy.Spec.Template.Spec.NodeSelector, k)
+		nodeSelector[k] = nil
+	}
+	patch, err := c.getNodeSelectorPatch(nodeSelector)
+	if err == nil {
+		_, err = c.kubeClient.AppsV1().DaemonSets(dae.Namespace).Patch(context.TODO(), dae.GetName(), types.StrategicMergePatchType, patch, metav1.PatchOptions{})
 	}
 
-	_, err = c.kubeClient.AppsV1().DaemonSets(dep.Namespace).Update(context.TODO(), depCopy, metav1.UpdateOptions{})
 	if err != nil {
-		return fmt.Errorf("scaling up daemonset %s.%s failed: %w", depCopy.GetName(), depCopy.Namespace, err)
+		return fmt.Errorf("scaling up daemonset %s.%s failed: %w", dae.GetName(), dae.Namespace, err)
 	}
 	return nil
 }
@@ -324,6 +322,16 @@ func (c *DaemonSetController) getSelectorLabel(daemonSet *appsv1.DaemonSet) (str
 	)
 }
 
+// createNodeSelectorPatch returns the nodeSelector field strategic patch used for scaling
+func (c *DaemonSetController) getNodeSelectorPatch(nodeSelector map[string]interface{}) ([]byte, error) {
+	nodeSelectorJSON, err := json.Marshal(nodeSelector)
+	if err != nil {
+		return nil, err
+	}
+	patch := []byte(fmt.Sprintf(`{"spec":{"template":{"spec":{"nodeSelector":%s}}}}`, nodeSelectorJSON))
+	return patch, nil
+}
+
 func (c *DaemonSetController) HaveDependenciesChanged(cd *flaggerv1.Canary) (bool, error) {
 	return c.configTracker.HasConfigChanged(cd)
 }