From aca623ce3fb5fedd981b9e6efeb930bfe7b2376b Mon Sep 17 00:00:00 2001
From: water <672684719@qq.com>
Date: Wed, 29 Jul 2026 06:25:46 +0800
Subject: [PATCH] fix: reject explicitly set empty index.store.type (GH#22550)

---
 .../cluster/metadata/MetadataCreateIndexService.java     | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/server/src/main/java/org/opensearch/cluster/metadata/MetadataCreateIndexService.java b/server/src/main/java/org/opensearch/cluster/metadata/MetadataCreateIndexService.java
index b603f7e93a880..70d62d7576406 100644
--- a/server/src/main/java/org/opensearch/cluster/metadata/MetadataCreateIndexService.java
+++ b/server/src/main/java/org/opensearch/cluster/metadata/MetadataCreateIndexService.java
@@ -1402,6 +1402,15 @@ public static void updatePluggableDataFormatSettings(
     }
 
     public static void validateStoreTypeSettings(Settings settings) {
+        // Reject explicitly set empty store type (GH#22550)
+        if (IndexModule.INDEX_STORE_TYPE_SETTING.exists(settings)) {
+            String storeType = IndexModule.INDEX_STORE_TYPE_SETTING.get(settings);
+            if (storeType.isEmpty()) {
+                throw new IllegalArgumentException(
+                    "Failed to parse value for setting [" + IndexModule.INDEX_STORE_TYPE_SETTING.getKey() + "] must not be empty"
+                );
+            }
+        }
         // deprecate simplefs store type:
         if (IndexModule.Type.SIMPLEFS.match(IndexModule.INDEX_STORE_TYPE_SETTING.get(settings))) {
             DEPRECATION_LOGGER.deprecate(