feat: record last state transition times

https://docs.google.com/document/d/14yPSZ9iLk7a0qEg14rNWr60Btz0HEeQ3oWKP-GN9QTM

Author: davidxia

ray-operator/apis/ray/v1/raycluster_types.go

@@ -141,6 +141,8 @@ type RayClusterStatus struct {
 	// LastUpdateTime indicates last update timestamp for this cluster status.
 	// +nullable
 	LastUpdateTime *metav1.Time `json:"lastUpdateTime,omitempty"`
+	// StateTransitionTimes indicates the time of the last state transition for each state.
+	StateTransitionTimes map[ClusterState]*metav1.Time `json:"stateTransitionTimes,omitempty"`
 	// Service Endpoints
 	Endpoints map[string]string `json:"endpoints,omitempty"`
 	// Head info

ray-operator/apis/ray/v1/zz_generated.deepcopy.go

@@ -1294,6 +1294,13 @@ func (r *RayClusterReconciler) calculateStatus(ctx context.Context, instance *ra
 	timeNow := metav1.Now()
 	newInstance.Status.LastUpdateTime = &timeNow
 
+	if instance.Status.State != newInstance.Status.State {
+		if newInstance.Status.StateTransitionTimes == nil {
+			newInstance.Status.StateTransitionTimes = make(map[rayv1.ClusterState]*metav1.Time)
+		}
+		newInstance.Status.StateTransitionTimes[newInstance.Status.State] = &timeNow
+	}
+
 	return newInstance, nil
 }