fix: support starting legacy stopped components with replicas=0

Author: zijiren233

controllers/apps/component/transformer_component_validation.go

@@ -66,6 +66,10 @@ func validateCompReplicas(comp *appsv1.Component, compDef *appsv1.ComponentDefin
 	}
 
 	replicas := comp.Spec.Replicas
+	// Backward compatibility: older stop flows persisted stopped components as replicas=0.
+	if replicas == 0 {
+		return nil
+	}
 	if replicas >= replicasLimit.MinReplicas && replicas <= replicasLimit.MaxReplicas {
 		return nil
 	}

controllers/apps/component/transformer_component_workload.go

@@ -43,11 +43,6 @@ import (
 	intctrlutil "github.com/apecloud/kubeblocks/pkg/controllerutil"
 )
 
-const (
-	// TODO: use replicas status
-	stopReplicasSnapshotKey = "apps.kubeblocks.io/stop-replicas-snapshot"
-)
-
 // componentWorkloadTransformer handles component workload generation
 type componentWorkloadTransformer struct {
 	client.Client
@@ -218,11 +213,15 @@ func (t *componentWorkloadTransformer) handleWorkloadStartNStop(transCtx *compon
 }
 
 func isCompStopped(synthesizedComp *component.SynthesizedComponent) bool {
-	return synthesizedComp.Stop != nil && *synthesizedComp.Stop
+	if synthesizedComp.Stop != nil && *synthesizedComp.Stop {
+		return true
+	}
+	// Backward compatibility: older stop flows persisted a stopped component as replicas=0.
+	return synthesizedComp.Replicas == 0
 }
 
 func isWorkloadStopped(runningITS *workloads.InstanceSet) bool {
-	_, ok := runningITS.Annotations[stopReplicasSnapshotKey]
+	_, ok := runningITS.Annotations[constant.StopReplicasSnapshotKey]
 	return ok
 }
 
@@ -241,7 +240,7 @@ func (t *componentWorkloadTransformer) stopWorkload(
 	protoITS.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled = appsv1.RetainPersistentVolumeClaimRetentionPolicyType
 
 	// backup the replicas of runningITS
-	snapshot, ok := runningITS.Annotations[stopReplicasSnapshotKey]
+	snapshot, ok := runningITS.Annotations[constant.StopReplicasSnapshotKey]
 	if !ok {
 		replicas := map[string]int32{}
 		if runningITS.Spec.Replicas != nil {
@@ -260,13 +259,13 @@ func (t *componentWorkloadTransformer) stopWorkload(
 
 		protoITS.Annotations[constant.KubeBlocksGenerationKey] = synthesizedComp.Generation
 	}
-	protoITS.Annotations[stopReplicasSnapshotKey] = snapshot
+	protoITS.Annotations[constant.StopReplicasSnapshotKey] = snapshot
 	return nil
 }
 
 func (t *componentWorkloadTransformer) startWorkload(
 	synthesizedComp *component.SynthesizedComponent, runningITS, protoITS *workloads.InstanceSet) error {
-	snapshot := runningITS.Annotations[stopReplicasSnapshotKey]
+	snapshot := runningITS.Annotations[constant.StopReplicasSnapshotKey]
 	replicas := map[string]int32{}
 	if err := json.Unmarshal([]byte(snapshot), &replicas); err != nil {
 		return err
@@ -292,8 +291,8 @@ func (t *componentWorkloadTransformer) startWorkload(
 		}
 	}
 
-	delete(protoITS.Annotations, stopReplicasSnapshotKey)
-	delete(runningITS.Annotations, stopReplicasSnapshotKey)
+	delete(protoITS.Annotations, constant.StopReplicasSnapshotKey)
+	delete(runningITS.Annotations, constant.StopReplicasSnapshotKey)
 
 	return nil
 }

pkg/constant/annotations.go

@@ -40,6 +40,8 @@ const (
 	PVLastClaimPolicyAnnotationKey       = "apps.kubeblocks.io/pv-last-claim-policy"
 	LastRoleSnapshotVersionAnnotationKey = "apps.kubeblocks.io/last-role-snapshot-version"
 	ComponentScaleInAnnotationKey        = "apps.kubeblocks.io/component-scale-in" // ComponentScaleInAnnotationKey specifies whether the component is scaled in
+	StopReplicasSnapshotKey              = "apps.kubeblocks.io/stop-replicas-snapshot"
+	SnapShotForStartAnnotationKey        = "kubeblocks.io/snapshot-for-start"
 
 	// SkipPreTerminateAnnotationKey specifies to skip the pre-terminate action for a component.
 	SkipPreTerminateAnnotationKey = "apps.kubeblocks.io/skip-pre-terminate"

pkg/operations/start.go

@@ -20,13 +20,15 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 package operations
 
 import (
+	"encoding/json"
 	"time"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	appsv1 "github.com/apecloud/kubeblocks/apis/apps/v1"
 	opsv1alpha1 "github.com/apecloud/kubeblocks/apis/operations/v1alpha1"
+	"github.com/apecloud/kubeblocks/pkg/constant"
 	intctrlcomp "github.com/apecloud/kubeblocks/pkg/controller/component"
 	intctrlutil "github.com/apecloud/kubeblocks/pkg/controllerutil"
 )
@@ -78,13 +80,20 @@ func (start StartOpsHandler) Action(reqCtx intctrlutil.RequestCtx, cli client.Cl
 			}
 		}
 		compSpec.Stop = nil
+		// Backward compatibility: older stop flows persisted stopped components as replicas=0.
+		if compSpec.Replicas == 0 {
+			restoreComponentReplicas(cluster, compSpec)
+		}
 	}
 	for i, v := range cluster.Spec.ComponentSpecs {
 		startComp(&cluster.Spec.ComponentSpecs[i], v.Name)
 	}
 	for i, v := range cluster.Spec.Shardings {
 		startComp(&cluster.Spec.Shardings[i].Template, v.Name)
 	}
+	if cluster.Annotations != nil {
+		delete(cluster.Annotations, constant.SnapShotForStartAnnotationKey)
+	}
 	return cli.Update(reqCtx.Ctx, cluster)
 }
 
@@ -112,3 +121,31 @@ func (start StartOpsHandler) ReconcileAction(reqCtx intctrlutil.RequestCtx, cli
 func (start StartOpsHandler) SaveLastConfiguration(reqCtx intctrlutil.RequestCtx, cli client.Client, opsRes *OpsResource) error {
 	return nil
 }
+
+func restoreComponentReplicas(cluster *appsv1.Cluster, compSpec *appsv1.ClusterComponentSpec) {
+	if cluster == nil || compSpec == nil {
+		return
+	}
+
+	snapshot := map[string]int32{}
+	if cluster.Annotations != nil {
+		if raw, ok := cluster.Annotations[constant.SnapShotForStartAnnotationKey]; ok && raw != "" {
+			if err := json.Unmarshal([]byte(raw), &snapshot); err != nil {
+				compSpec.Replicas = 1
+				return
+			}
+		}
+	}
+
+	if replicas, ok := snapshot[""]; ok && replicas > 0 {
+		compSpec.Replicas = replicas
+	} else {
+		compSpec.Replicas = 1
+	}
+
+	for i := range compSpec.Instances {
+		if replicas, ok := snapshot[compSpec.Instances[i].Name]; ok {
+			compSpec.Instances[i].Replicas = &replicas
+		}
+	}
+}