feat: updated sharding cache getter func

Signed-off-by: Soumya Ghosh Dastidar <gdsoumya@gmail.com>

cmd/argocd-application-controller/commands/argocd_application_controller.go

@@ -10,7 +10,6 @@ import (
 	"github.com/redis/go-redis/v9"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
-	appsv1 "k8s.io/api/apps/v1"
 	kubeerrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
@@ -148,7 +147,8 @@ func NewCommand() *cobra.Command {
 				appController.InvalidateProjectsCache()
 			}))
 			kubectl := kubeutil.NewKubectl()
-			clusterSharding := getClusterSharding(kubeClient, settingsMgr, shardingAlgorithm, enableDynamicClusterDistribution)
+			clusterSharding, err := getClusterSharding(kubeClient, settingsMgr, shardingAlgorithm, enableDynamicClusterDistribution)
+			errors.CheckError(err)
 			appController, err = controller.NewApplicationController(
 				namespace,
 				settingsMgr,
@@ -240,37 +240,37 @@ func NewCommand() *cobra.Command {
 	return &command
 }
 
-func getClusterSharding(kubeClient *kubernetes.Clientset, settingsMgr *settings.SettingsManager, shardingAlgorithm string, enableDynamicClusterDistribution bool) sharding.ClusterShardingCache {
-	var replicasCount int
-	// StatefulSet mode and Deployment mode uses different default values for shard number.
-	defaultShardNumberValue := 0
-	applicationControllerName := env.StringFromEnv(common.EnvAppControllerName, common.DefaultApplicationControllerName)
-
+func getClusterSharding(kubeClient *kubernetes.Clientset, settingsMgr *settings.SettingsManager, shardingAlgorithm string, enableDynamicClusterDistribution bool) (sharding.ClusterShardingCache, error) {
 	var (
-		appControllerDeployment *appsv1.Deployment
-		err                     error
+		replicasCount int
 	)
+	// StatefulSet mode and Deployment mode uses different default values for shard number.
+	defaultShardNumberValue := 0
 
-	// skip deployment fetching if dynamic sharding is disabled
 	if enableDynamicClusterDistribution {
-		appControllerDeployment, err = kubeClient.AppsV1().Deployments(settingsMgr.GetNamespace()).Get(context.Background(), applicationControllerName, metav1.GetOptions{})
-		// if the application controller deployment was not found, the Get() call returns an empty Deployment object. So, set the variable to nil explicitly
-		if err != nil && kubeerrors.IsNotFound(err) {
-			appControllerDeployment = nil
+		applicationControllerName := env.StringFromEnv(common.EnvAppControllerName, common.DefaultApplicationControllerName)
+		appControllerDeployment, err := kubeClient.AppsV1().Deployments(settingsMgr.GetNamespace()).Get(context.Background(), applicationControllerName, metav1.GetOptions{})
+
+		// if app controller deployment is not found when dynamic cluster distribution is enabled error out
+		if err != nil {
+			return nil, fmt.Errorf("(dymanic cluster distribution) failed to get app controller deployment: %v", err)
+		}
+
+		if appControllerDeployment != nil && appControllerDeployment.Spec.Replicas != nil {
+			replicasCount = int(*appControllerDeployment.Spec.Replicas)
+			defaultShardNumberValue = -1
+		} else {
+			return nil, fmt.Errorf("(dymanic cluster distribution) failed to get app controller deployment replica count")
 		}
-	}
 
-	if enableDynamicClusterDistribution && appControllerDeployment != nil && appControllerDeployment.Spec.Replicas != nil {
-		replicasCount = int(*appControllerDeployment.Spec.Replicas)
-		defaultShardNumberValue = -1
 	} else {
 		replicasCount = env.ParseNumFromEnv(common.EnvControllerReplicas, 0, 0, math.MaxInt32)
 	}
 	shardNumber := env.ParseNumFromEnv(common.EnvControllerShard, defaultShardNumberValue, -math.MaxInt32, math.MaxInt32)
 	if replicasCount > 1 {
 		// check for shard mapping using configmap if application-controller is a deployment
 		// else use existing logic to infer shard from pod name if application-controller is a statefulset
-		if enableDynamicClusterDistribution && appControllerDeployment != nil {
+		if enableDynamicClusterDistribution {
 			var err error
 			// retry 3 times if we find a conflict while updating shard mapping configMap.
 			// If we still see conflicts after the retries, wait for next iteration of heartbeat process.
@@ -298,5 +298,5 @@ func getClusterSharding(kubeClient *kubernetes.Clientset, settingsMgr *settings.
 		log.Info("Processing all cluster shards")
 	}
 	db := db.NewDB(settingsMgr.GetNamespace(), settingsMgr, kubeClient)
-	return sharding.NewClusterSharding(db, shardNumber, replicasCount, shardingAlgorithm)
+	return sharding.NewClusterSharding(db, shardNumber, replicasCount, shardingAlgorithm), nil
 }