More PR feedback.

Signed-off-by: Marc Handalian <marc.handalian@gmail.com>

Author: mch2

server/src/main/java/org/opensearch/cluster/metadata/MetadataCreateIndexService.java

@@ -1008,22 +1008,18 @@ static Settings aggregateIndexSettings(
 
     private static void updateSearchOnlyReplicas(Settings requestSettings, Settings.Builder builder) {
         if (INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.exists(builder) && builder.get(SETTING_NUMBER_OF_SEARCH_REPLICAS) != null) {
+            if (INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.get(requestSettings) > 0
+                && ReplicationType.parseString(builder.get(INDEX_REPLICATION_TYPE_SETTING.getKey())).equals(ReplicationType.DOCUMENT)) {
+                throw new IllegalArgumentException(
+                    "To set "
+                        + SETTING_NUMBER_OF_SEARCH_REPLICAS
+                        + ", "
+                        + INDEX_REPLICATION_TYPE_SETTING.getKey()
+                        + " must be set to "
+                        + ReplicationType.SEGMENT
+                );
+            }
             builder.put(SETTING_NUMBER_OF_SEARCH_REPLICAS, INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.get(requestSettings));
-        } else {
-            // ensure we always set the default on creation to a nonnull value.
-            // TODO: Maybe allow a cluster wide default for search replica count when SR is default strategy
-            builder.put(SETTING_NUMBER_OF_SEARCH_REPLICAS, INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.getDefault(requestSettings));
-        }
-        if (INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.get(requestSettings) > 0
-            && ReplicationType.parseString(builder.get(INDEX_REPLICATION_TYPE_SETTING.getKey())).equals(ReplicationType.DOCUMENT)) {
-            throw new IllegalArgumentException(
-                "To set "
-                    + SETTING_NUMBER_OF_SEARCH_REPLICAS
-                    + ", "
-                    + INDEX_REPLICATION_TYPE_SETTING.getKey()
-                    + " must be set to "
-                    + ReplicationType.SEGMENT
-            );
         }
     }
 

server/src/main/java/org/opensearch/cluster/metadata/MetadataUpdateSettingsService.java

@@ -270,7 +270,7 @@ public ClusterState execute(ClusterState currentState) {
                         }
                         final int updatedNumberOfSearchReplicas = IndexMetadata.INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.get(openSettings);
                         if (preserveExisting == false) {
-                            // TODO: Maybe honor awareness validation to search replicas?
+                            // TODO: Honor awareness validation to search replicas.
 
                             // Verify that this won't take us over the cluster shard limit.
                             int totalNewShards = Arrays.stream(request.indices())

server/src/test/java/org/opensearch/cluster/metadata/MetadataCreateIndexServiceTests.java

@@ -128,6 +128,7 @@
 import static java.util.Collections.singleton;
 import static java.util.Collections.singletonList;
 import static org.opensearch.cluster.metadata.IndexMetadata.INDEX_NUMBER_OF_ROUTING_SHARDS_SETTING;
+import static org.opensearch.cluster.metadata.IndexMetadata.INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING;
 import static org.opensearch.cluster.metadata.IndexMetadata.INDEX_NUMBER_OF_SHARDS_SETTING;
 import static org.opensearch.cluster.metadata.IndexMetadata.INDEX_READ_ONLY_BLOCK;
 import static org.opensearch.cluster.metadata.IndexMetadata.INDEX_REPLICATION_TYPE_SETTING;
@@ -2250,7 +2251,7 @@ public void testDefaultSearchReplicasSetting() {
             Collections.emptySet(),
             clusterSettings
         );
-        assertEquals("0", indexSettings.get(SETTING_NUMBER_OF_SEARCH_REPLICAS));
+        assertFalse(INDEX_NUMBER_OF_SEARCH_REPLICAS_SETTING.exists(indexSettings));
     }
 
     public void testSearchReplicasValidationWithSegmentReplication() {