From c694d96e54459a511b6ad1a52f0f83dacfd98591 Mon Sep 17 00:00:00 2001
From: Koorous Vargha <kvargha@linkedin.com>
Date: Thu, 26 Sep 2024 19:03:12 -0700
Subject: [PATCH] [controller] Ensure empty string from config doesn't result
 in an array of an empty string (#1202)

---
 .../venice/utils/VeniceProperties.java        |  1 +
 .../venice/controller/TestHAASController.java | 21 +++++++++++++++++++
 .../VeniceControllerClusterConfig.java        |  8 ++++++-
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/internal/venice-client-common/src/main/java/com/linkedin/venice/utils/VeniceProperties.java b/internal/venice-client-common/src/main/java/com/linkedin/venice/utils/VeniceProperties.java
index dfafe3ef15..e9855ece93 100644
--- a/internal/venice-client-common/src/main/java/com/linkedin/venice/utils/VeniceProperties.java
+++ b/internal/venice-client-common/src/main/java/com/linkedin/venice/utils/VeniceProperties.java
@@ -389,6 +389,7 @@ public List<String> getList(String key, List<String> defaultValue) {
     }
 
     String value = get(key);
+
     String[] pieces = value.split("\\s*,\\s*");
     return Arrays.asList(pieces);
   }
diff --git a/internal/venice-test-common/src/integrationTest/java/com/linkedin/venice/controller/TestHAASController.java b/internal/venice-test-common/src/integrationTest/java/com/linkedin/venice/controller/TestHAASController.java
index 796edb2aa2..905a853693 100644
--- a/internal/venice-test-common/src/integrationTest/java/com/linkedin/venice/controller/TestHAASController.java
+++ b/internal/venice-test-common/src/integrationTest/java/com/linkedin/venice/controller/TestHAASController.java
@@ -78,6 +78,27 @@ public void testClusterResourceInstanceTag() {
     }
   }
 
+  @Test(timeOut = 60 * Time.MS_PER_SECOND)
+  public void testClusterResourceEmptyInstanceTag() {
+    try (VeniceClusterWrapper venice = ServiceFactory.getVeniceCluster(0, 0, 0, 1);
+        HelixAsAServiceWrapper helixAsAServiceWrapper = startAndWaitForHAASToBeAvailable(venice.getZk().getAddress())) {
+      String instanceTag = "";
+      String controllerClusterName = "venice-controllers";
+
+      Properties clusterProperties = (Properties) enableControllerAndStorageClusterHAASProperties.clone();
+      clusterProperties.put(ConfigKeys.CONTROLLER_RESOURCE_INSTANCE_GROUP_TAG, instanceTag);
+      clusterProperties.put(ConfigKeys.CONTROLLER_INSTANCE_TAG_LIST, instanceTag);
+
+      VeniceControllerWrapper controllerWrapper = venice.addVeniceController(clusterProperties);
+
+      HelixAdmin helixAdmin = controllerWrapper.getVeniceHelixAdmin().getHelixAdmin();
+      List<String> resources = helixAdmin.getResourcesInClusterWithTag(controllerClusterName, instanceTag);
+      assertEquals(resources.size(), 0);
+      List<String> instances = helixAdmin.getInstancesInClusterWithTag(controllerClusterName, instanceTag);
+      assertEquals(instances.size(), 0);
+    }
+  }
+
   @Test(timeOut = 60 * Time.MS_PER_SECOND)
   public void testStartHAASHelixControllerAsControllerClusterLeader() {
     try (VeniceClusterWrapper venice = ServiceFactory.getVeniceCluster(0, 0, 0, 1);
diff --git a/services/venice-controller/src/main/java/com/linkedin/venice/controller/VeniceControllerClusterConfig.java b/services/venice-controller/src/main/java/com/linkedin/venice/controller/VeniceControllerClusterConfig.java
index e0c1881e05..7d390d3b99 100644
--- a/services/venice-controller/src/main/java/com/linkedin/venice/controller/VeniceControllerClusterConfig.java
+++ b/services/venice-controller/src/main/java/com/linkedin/venice/controller/VeniceControllerClusterConfig.java
@@ -654,7 +654,13 @@ public VeniceControllerClusterConfig(VeniceProperties props) {
     this.adminCheckReadMethodForKafka = props.getBoolean(ADMIN_CHECK_READ_METHOD_FOR_KAFKA, true);
     this.controllerClusterName = props.getString(CONTROLLER_CLUSTER, "venice-controllers");
     this.controllerResourceInstanceGroupTag = props.getString(CONTROLLER_RESOURCE_INSTANCE_GROUP_TAG, "");
-    this.controllerInstanceTagList = props.getList(CONTROLLER_INSTANCE_TAG_LIST, Collections.emptyList());
+
+    if (props.getString(CONTROLLER_INSTANCE_TAG_LIST, "").isEmpty()) {
+      this.controllerInstanceTagList = Collections.emptyList();
+    } else {
+      this.controllerInstanceTagList = props.getList(CONTROLLER_INSTANCE_TAG_LIST, Collections.emptyList());
+    }
+
     this.controllerClusterReplica = props.getInt(CONTROLLER_CLUSTER_REPLICA, 3);
     this.controllerClusterZkAddress = props.getString(CONTROLLER_CLUSTER_ZK_ADDRESSS, getZkAddress());
     this.parent = props.getBoolean(CONTROLLER_PARENT_MODE, false);