Adding number of routing shards to index settings before passing into…

… GetSettingsResponse

Signed-off-by: Sophia <tjdud6024@gmail.com>

CHANGELOG.md

@@ -39,6 +39,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix the computed max shards of cluster to avoid int overflow ([#14155](https://github.com/opensearch-project/OpenSearch/pull/14155))
 - Fixed rest-high-level client searchTemplate & mtermVectors endpoints to have a leading slash ([#14465](https://github.com/opensearch-project/OpenSearch/pull/14465))
 - Write shard level metadata blob when snapshotting searchable snapshot indexes ([#13190](https://github.com/opensearch-project/OpenSearch/pull/13190))
+- Updated GET {index}/_settings to return `number_of_routing_shards` ([#14446](https://github.com/opensearch-project/OpenSearch/pull/14446))
 
 ### Security
 

rest-api-spec/src/main/resources/rest-api-spec/test/indices.get_settings/10_basic.yml

@@ -14,6 +14,7 @@ setup:
             settings:
               number_of_shards: 3
               number_of_replicas: 0
+              number_of_routing_shards: 6
 
 ---
 "Get /_settings":
@@ -25,6 +26,7 @@ setup:
  - match: { test_1.settings.index.number_of_replicas: "1"}
  - match: { test_2.settings.index.number_of_shards: "3"}
  - match: { test_2.settings.index.number_of_replicas: "0"}
+ - match: { test_2.settings.index.number_of_routing_shards: "6"}
 
 ---
 "Get /{index}/_settings":
@@ -109,6 +111,7 @@ setup:
  - match: { test_2.settings.index.number_of_shards: "3"}
  - is_false: test_1.settings.index.number_of_replicas
  - is_false: test_2.settings.index.number_of_replicas
+ - is_false: test_2.settings.index.number_of_routing_shards
 
 ---
 "Get /_all/_settings/{name}":
@@ -122,6 +125,7 @@ setup:
  - match: { test_2.settings.index.number_of_shards: "3"}
  - is_false: test_1.settings.index.number_of_replicas
  - is_false: test_2.settings.index.number_of_replicas
+ - is_false: test_2.settings.index.number_of_routing_shards
 
 
 ---
@@ -136,6 +140,7 @@ setup:
  - match: { test_2.settings.index.number_of_shards: "3"}
  - is_false: test_1.settings.index.number_of_replicas
  - is_false: test_2.settings.index.number_of_replicas
+ - is_false: test_2.settings.index.number_of_routing_shards
 
 ---
 "Get /index,index/_settings/{name}":
@@ -149,6 +154,7 @@ setup:
  - match: { test_2.settings.index.number_of_shards: "3"}
  - is_false: test_1.settings.index.number_of_replicas
  - is_false: test_2.settings.index.number_of_replicas
+ - is_false: test_2.settings.index.number_of_routing_shards
 
 ---
 "Get /index*/_settings/{name}":
@@ -161,6 +167,7 @@ setup:
  - match: { test_2.settings.index.number_of_shards: "3"}
  - is_false: test_1
  - is_false: test_2.settings.index.number_of_replicas
+ - is_false: test_2.settings.index.number_of_routing_shards
 
 ---
 "Get /_settings with local flag":

server/src/main/java/org/opensearch/action/admin/indices/settings/get/TransportGetSettingsAction.java

@@ -130,6 +130,11 @@ protected void clusterManagerOperation(GetSettingsRequest request, ClusterState
                 indexSettings = indexSettings.filter(k -> Regex.simpleMatch(request.names(), k));
             }
 
+            indexSettings = Settings.builder()
+                .put(indexSettings)
+                .put(IndexMetadata.INDEX_NUMBER_OF_ROUTING_SHARDS_SETTING.getKey(), indexMetadata.getRoutingNumShards())
+                .build();
+
             indexToSettingsBuilder.put(concreteIndex.getName(), indexSettings);
             if (request.includeDefaults()) {
                 Settings defaultSettings = settingsFilter.filter(indexScopedSettings.diff(indexSettings, Settings.EMPTY));