Make RunnerSet much more reliable with or without webhook

api/v1alpha1/runnerset_types.go

@@ -25,6 +25,14 @@ import (
 type RunnerSetSpec struct {
 	RunnerConfig `json:",inline"`
 
+	// EffectiveTime is the time the upstream controller requested to sync Replicas.
+	// It is usually populated by the webhook-based autoscaler via HRA.
+	// It is used to prevent ephemeral runners from unnecessarily recreated.
+	//
+	// +optional
+	// +nullable
+	EffectiveTime *metav1.Time `json:"effectiveTime,omitempty"`
+
 	appsv1.StatefulSetSpec `json:",inline"`
 }
 

api/v1alpha1/zz_generated.deepcopy.go

@@ -932,6 +932,10 @@ func (in *RunnerSetList) DeepCopyObject() runtime.Object {
 func (in *RunnerSetSpec) DeepCopyInto(out *RunnerSetSpec) {
 	*out = *in
 	in.RunnerConfig.DeepCopyInto(&out.RunnerConfig)
+	if in.EffectiveTime != nil {
+		in, out := &in.EffectiveTime, &out.EffectiveTime
+		*out = (*in).DeepCopy()
+	}
 	in.StatefulSetSpec.DeepCopyInto(&out.StatefulSetSpec)
 }