Avoid syncing when possible (#1274)

Avoid extra syncing in case there are no changes in pooler requirements.
Add pooler specific labels to pooler secrets.
Add test case to check for pooler secret creation and deletion.

Co-authored-by: Rafia Sabih <rafia.sabih@zalando.de>

pkg/cluster/connection_pooler.go

@@ -539,13 +539,13 @@ func updateConnectionPoolerAnnotations(KubeClient k8sutil.KubernetesClient, depl
 // Test if two connection pooler configuration needs to be synced. For simplicity
 // compare not the actual K8S objects, but the configuration itself and request
 // sync if there is any difference.
-func needSyncConnectionPoolerSpecs(oldSpec, newSpec *acidv1.ConnectionPooler) (sync bool, reasons []string) {
+func needSyncConnectionPoolerSpecs(oldSpec, newSpec *acidv1.ConnectionPooler, logger *logrus.Entry) (sync bool, reasons []string) {
 	reasons = []string{}
 	sync = false
 
 	changelog, err := diff.Diff(oldSpec, newSpec)
 	if err != nil {
-		//c.logger.Infof("Cannot get diff, do not do anything, %+v", err)
+		logger.Infof("cannot get diff, do not do anything, %+v", err)
 		return false, reasons
 	}
 
@@ -681,13 +681,45 @@ func logPoolerEssentials(log *logrus.Entry, oldSpec, newSpec *acidv1.Postgresql)
 }
 
 func (c *Cluster) syncConnectionPooler(oldSpec, newSpec *acidv1.Postgresql, LookupFunction InstallFunction) (SyncReason, error) {
-	logPoolerEssentials(c.logger, oldSpec, newSpec)
 
 	var reason SyncReason
 	var err error
 	var newNeedConnectionPooler, oldNeedConnectionPooler bool
 	oldNeedConnectionPooler = false
 
+	if oldSpec == nil {
+		oldSpec = &acidv1.Postgresql{
+			Spec: acidv1.PostgresSpec{
+				ConnectionPooler: &acidv1.ConnectionPooler{},
+			},
+		}
+	}
+
+	needSync, _ := needSyncConnectionPoolerSpecs(oldSpec.Spec.ConnectionPooler, newSpec.Spec.ConnectionPooler, c.logger)
+	masterChanges, err := diff.Diff(oldSpec.Spec.EnableConnectionPooler, newSpec.Spec.EnableConnectionPooler)
+	if err != nil {
+		c.logger.Error("Error in getting diff of master connection pooler changes")
+	}
+	replicaChanges, err := diff.Diff(oldSpec.Spec.EnableReplicaConnectionPooler, newSpec.Spec.EnableReplicaConnectionPooler)
+	if err != nil {
+		c.logger.Error("Error in getting diff of replica connection pooler changes")
+	}
+
+	// skip pooler sync only
+	// 1. if there is no diff in spec, AND
+	// 2. if connection pooler is already there and is also required as per newSpec
+	//
+	// Handling the case when connectionPooler is not there but it is required
+	// as per spec, hence do not skip syncing in that case, even though there
+	// is no diff in specs
+	if (!needSync && len(masterChanges) <= 0 && len(replicaChanges) <= 0) &&
+		(c.ConnectionPooler != nil && *newSpec.Spec.EnableConnectionPooler) {
+		c.logger.Debugln("syncing pooler is not required")
+		return nil, nil
+	}
+
+	logPoolerEssentials(c.logger, oldSpec, newSpec)
+
 	// Check and perform the sync requirements for each of the roles.
 	for _, role := range [2]PostgresRole{Master, Replica} {
 
@@ -841,7 +873,7 @@ func (c *Cluster) syncConnectionPoolerWorker(oldSpec, newSpec *acidv1.Postgresql
 		var specReason []string
 
 		if oldSpec != nil {
-			specSync, specReason = needSyncConnectionPoolerSpecs(oldConnectionPooler, newConnectionPooler)
+			specSync, specReason = needSyncConnectionPoolerSpecs(oldConnectionPooler, newConnectionPooler, c.logger)
 		}
 
 		defaultsSync, defaultsReason := needSyncConnectionPoolerDefaults(&c.Config, newConnectionPooler, deployment)

pkg/cluster/k8sres.go

@@ -1561,11 +1561,17 @@ func (c *Cluster) generateSingleUserSecret(namespace string, pgUser spec.PgUser)
 	}
 
 	username := pgUser.Name
+	lbls := c.labelsSet(true)
+
+	if username == constants.ConnectionPoolerUserName {
+		lbls = c.connectionPoolerLabels("", false).MatchLabels
+	}
+
 	secret := v1.Secret{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:        c.credentialSecretName(username),
 			Namespace:   namespace,
-			Labels:      c.labelsSet(true),
+			Labels:      lbls,
 			Annotations: c.annotationsSet(nil),
 		},
 		Type: v1.SecretTypeOpaque,
@@ -1574,6 +1580,7 @@ func (c *Cluster) generateSingleUserSecret(namespace string, pgUser spec.PgUser)
 			"password": []byte(pgUser.Password),
 		},
 	}
+
 	return &secret
 }