fix: dynamic cluster distribution issue 20965, update the shard…

controller/appcontroller.go

@@ -288,9 +288,32 @@ func NewApplicationController(
 					return fmt.Errorf("application controller deployment replicas is not set or is less than 0, replicas: %d", appControllerDeployment.Spec.Replicas)
 				}
 				shard := env.ParseNumFromEnv(common.EnvControllerShard, -1, -math.MaxInt32, math.MaxInt32)
-				if _, err := sharding.GetOrUpdateShardFromConfigMap(kubeClientset.(*kubernetes.Clientset), settingsMgr, int(*appControllerDeployment.Spec.Replicas), shard); err != nil {
+				shard, err := sharding.GetOrUpdateShardFromConfigMap(kubeClientset.(*kubernetes.Clientset), settingsMgr, int(*appControllerDeployment.Spec.Replicas), shard)
+				if err != nil {
 					return fmt.Errorf("error while updating the heartbeat for to the Shard Mapping ConfigMap: %w", err)
 				}
+
+				// update the shard number in the clusterSharding, and resync all applications if the shard number is updated
+				if ctrl.clusterSharding.UpdateShard(shard) {
+					// update shard number in stateCache
+					ctrl.stateCache.UpdateShard(shard)
+
+					// resync all applications
+					apps, err := ctrl.appLister.List(labels.Everything())
+					if err != nil {
+						return err
+					}
+					for _, app := range apps {
+						if !ctrl.canProcessApp(app) {
+							continue
+						}
+						key, err := cache.MetaNamespaceKeyFunc(app)
+						if err == nil {
+							ctrl.appRefreshQueue.AddRateLimited(key)
+							ctrl.clusterSharding.AddApp(app)
+						}
+					}
+				}
 			}
 		}
 		return nil

controller/cache/cache.go

@@ -153,6 +153,8 @@ type LiveStateCache interface {
 	GetClustersInfo() []clustercache.ClusterInfo
 	// Init must be executed before cache can be used
 	Init() error
+	// UpdateShard will update the shard of ClusterSharding when the shard has changed.
+	UpdateShard(shard int) bool
 }
 
 type ObjectUpdatedHandler = func(managedByApp map[string]bool, ref v1.ObjectReference)
@@ -912,3 +914,8 @@ func (c *liveStateCache) GetClustersInfo() []clustercache.ClusterInfo {
 func (c *liveStateCache) GetClusterCache(server string) (clustercache.ClusterCache, error) {
 	return c.getSyncedCluster(server)
 }
+
+// UpdateShard will update the shard of ClusterSharding when the shard has changed.
+func (c *liveStateCache) UpdateShard(shard int) bool {
+	return c.clusterSharding.UpdateShard(shard)
+}

controller/sharding/cache.go

@@ -19,6 +19,8 @@ type ClusterShardingCache interface {
 	UpdateApp(a *v1alpha1.Application)
 	IsManagedCluster(c *v1alpha1.Cluster) bool
 	GetDistribution() map[string]int
+	GetAppDistribution() map[string]int
+	UpdateShard(shard int) bool
 }
 
 type ClusterSharding struct {
@@ -243,3 +245,33 @@ func (sharding *ClusterSharding) UpdateApp(a *v1alpha1.Application) {
 		log.Debugf("Skipping sharding distribution update. No relevant changes")
 	}
 }
+
+// GetAppDistribution should be not be called from a DestributionFunction because
+// it could cause a deadlock when updateDistribution is called.
+func (sharding *ClusterSharding) GetAppDistribution() map[string]int {
+	sharding.lock.RLock()
+	clusters := sharding.Clusters
+	apps := sharding.Apps
+	sharding.lock.RUnlock()
+
+	appDistribution := make(map[string]int, len(clusters))
+
+	for _, a := range apps {
+		if _, ok := appDistribution[a.Spec.Destination.Server]; !ok {
+			appDistribution[a.Spec.Destination.Server] = 0
+		}
+		appDistribution[a.Spec.Destination.Server]++
+	}
+	return appDistribution
+}
+
+// UpdateShard will update the shard of ClusterSharding when the shard has changed.
+func (sharding *ClusterSharding) UpdateShard(shard int) bool {
+	if shard != sharding.Shard {
+		sharding.lock.RLock()
+		sharding.Shard = shard
+		sharding.lock.RUnlock()
+		return true
+	}
+	return false
+}

controller/sharding/sharding.go

@@ -490,7 +490,10 @@ func GetClusterSharding(kubeClient kubernetes.Interface, settingsMgr *settings.S
 					err = fmt.Errorf("unable to get shard due to error updating the sharding config map: %w", err)
 					break
 				}
-				log.Warnf("conflict when getting shard from shard mapping configMap. Retrying (%d/3)", i)
+				// if `err == nil`, should not log the following warning message
+				if err != nil {
+					log.Warnf("conflict when getting shard from shard mapping configMap. Retrying (%d/3)", i)
+				}
 			}
 			errors.CheckError(err)
 		} else {