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/40_routing_shards_returned.yml

@@ -0,0 +1,183 @@
+---
+setup:
+  - skip:
+      version: " - 2.15.99"
+      reason: "number_of_routing_shards returned starting in 2.16.0"
+  - do:
+      indices.create:
+        index: test_1
+        body:
+          settings:
+            number_of_shards: 5
+            number_of_replicas: 1
+  - do:
+      indices.create:
+        index: test_2
+        body:
+          settings:
+            number_of_shards: 3
+            number_of_replicas: 0
+            number_of_routing_shards: 6
+
+---
+"Get /_settings":
+
+  - do:
+      indices.get_settings: {}
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - 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_replicas: "6"}
+
+---
+"Get /{index}/_settings":
+
+  - do:
+      indices.get_settings:
+        index: test_1
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - match: { test_1.settings.index.number_of_replicas: "1"}
+  - is_false: test_2
+
+
+---
+"Get /{index}/_settings/_all":
+
+  - do:
+      indices.get_settings:
+        index: test_1
+        name:  _all
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - match: { test_1.settings.index.number_of_replicas: "1"}
+  - is_false: test_2
+
+---
+"Get /{index}/_settings/*":
+
+  - do:
+      indices.get_settings:
+        index: test_1
+        name:  '*'
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - match: { test_1.settings.index.number_of_replicas: "1"}
+  - is_false: test_2
+
+---
+"Get /{index}/_settings/{name}":
+
+  - do:
+      indices.get_settings:
+        index: test_1
+        name:  index.number_of_shards
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - is_false: test_1.settings.index.number_of_replicas
+  - is_false: test_2
+
+---
+"Get /{index}/_settings/{name,name}":
+
+  - do:
+      indices.get_settings:
+        index: test_1
+        name:  index.number_of_shards,index.number_of_replicas
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - match: { test_1.settings.index.number_of_replicas: "1"}
+  - is_false: test_2
+
+---
+"Get /{index}/_settings/{name*}":
+
+  - do:
+      indices.get_settings:
+        index: test_1
+        name:  'index.number_of_s*'
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - is_false: test_1.settings.index.number_of_replicas
+  - is_false: test_2
+
+---
+"Get /_settings/{name}":
+
+  - do:
+      indices.get_settings:
+        name: index.number_of_shards
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - 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}":
+
+  - do:
+      indices.get_settings:
+        index: _all
+        name: index.number_of_shards
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - 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 /*/_settings/{name}":
+
+  - do:
+      indices.get_settings:
+        index: '*'
+        name: index.number_of_shards
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - 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}":
+
+  - do:
+      indices.get_settings:
+        index: test_1,test_2
+        name: index.number_of_shards
+
+  - match: { test_1.settings.index.number_of_shards: "5"}
+  - 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}":
+
+  - do:
+      indices.get_settings:
+        index: '*2'
+        name: index.number_of_shards
+
+  - 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":
+
+  - do:
+      indices.get_settings:
+        local: true
+
+  - is_true: test_1
+  - is_true: test_2

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

@@ -121,7 +121,12 @@ protected void clusterManagerOperation(GetSettingsRequest request, ClusterState
                 continue;
             }
 
-            Settings indexSettings = settingsFilter.filter(indexMetadata.getSettings());
+            Settings indexSettingsWithRoutingShards = Settings.builder()
+                .put(indexMetadata.getSettings())
+                .put(IndexMetadata.INDEX_NUMBER_OF_ROUTING_SHARDS_SETTING.getKey(), indexMetadata.getRoutingNumShards())
+                .build();
+
+            Settings indexSettings = settingsFilter.filter(indexSettingsWithRoutingShards);
             if (request.humanReadable()) {
                 indexSettings = IndexMetadata.addHumanReadableSettings(indexSettings);
             }