Incorporated comments

Signed-off-by: Dhwanil Patel <dhwanip@amazon.com>

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Provide service accounts tokens to extensions ([#9618](https://github.com/opensearch-project/OpenSearch/pull/9618))
 - Configurable merge policy for index with an option to choose from LogByteSize and Tiered merge policy ([#9992](https://github.com/opensearch-project/OpenSearch/pull/9992))
 - Download functionality of global metadata from remote store ([#10535](https://github.com/opensearch-project/OpenSearch/pull/10535))
+
 ### Dependencies
 - Bump `log4j-core` from 2.18.0 to 2.19.0
 - Bump `forbiddenapis` from 3.3 to 3.4

server/src/internalClusterTest/java/org/opensearch/gateway/remote/RemoteClusterStateServiceIT.java

@@ -86,10 +86,10 @@ public void testFullClusterRestoreStaleDelete() throws Exception {
 
         assertEquals(10, repository.blobStore().blobContainer(baseMetadataPath.add("manifest")).listBlobsByPrefix("manifest").size());
 
-        Map<String, IndexMetadata> indexMetadataMap = remoteClusterStateService.getLatestIndexMetadata(
+        Map<String, IndexMetadata> indexMetadataMap = remoteClusterStateService.getLatestMetadata(
             cluster().getClusterName(),
             getClusterState().metadata().clusterUUID()
-        );
+        ).getIndices();
         assertEquals(0, indexMetadataMap.values().stream().findFirst().get().getNumberOfReplicas());
         assertEquals(shardCount, indexMetadataMap.values().stream().findFirst().get().getNumberOfShards());
     }

server/src/main/java/org/opensearch/gateway/remote/RemoteClusterStateService.java

@@ -517,18 +517,14 @@ private BlobPath getManifestFolderPath(String clusterName, String clusterUUID) {
      *
      * @param clusterUUID uuid of cluster state to refer to in remote
      * @param clusterName name of the cluster
+     * @param clusterMetadataManifest manifest file of cluster
      * @return {@code Map<String, IndexMetadata>} latest IndexUUID to IndexMetadata map
      */
-    public Map<String, IndexMetadata> getLatestIndexMetadata(String clusterName, String clusterUUID) throws IOException {
-        start();
-        Map<String, IndexMetadata> remoteIndexMetadata = new HashMap<>();
-        Optional<ClusterMetadataManifest> clusterMetadataManifest = getLatestClusterMetadataManifest(clusterName, clusterUUID);
-        if (!clusterMetadataManifest.isPresent()) {
-            throw new IllegalStateException("Latest index metadata is not present for the provided clusterUUID");
-        }
-        assert Objects.equals(clusterUUID, clusterMetadataManifest.get().getClusterUUID())
+    private Map<String, IndexMetadata> getIndexMetadataMap(String clusterName, String clusterUUID, ClusterMetadataManifest clusterMetadataManifest) throws IOException {
+        assert Objects.equals(clusterUUID, clusterMetadataManifest.getClusterUUID())
             : "Corrupt ClusterMetadataManifest found. Cluster UUID mismatch.";
-        for (UploadedIndexMetadata uploadedIndexMetadata : clusterMetadataManifest.get().getIndices()) {
+        Map<String, IndexMetadata> remoteIndexMetadata = new HashMap<>();
+        for (UploadedIndexMetadata uploadedIndexMetadata : clusterMetadataManifest.getIndices()) {
             IndexMetadata indexMetadata = getIndexMetadata(clusterName, clusterUUID, uploadedIndexMetadata);
             remoteIndexMetadata.put(uploadedIndexMetadata.getIndexUUID(), indexMetadata);
         }
@@ -560,26 +556,41 @@ private IndexMetadata getIndexMetadata(String clusterName, String clusterUUID, U
     }
 
     /**
-     * Fetch global metadata from remote cluster state
+     * Fetch latest metadata from remote cluster state including global metadata and index metadata
      *
      * @param clusterUUID uuid of cluster state to refer to in remote
      * @param clusterName name of the cluster
      * @return {@link IndexMetadata}
      */
-    public Metadata getGlobalMetadata(String clusterName, String clusterUUID) {
+    public Metadata getLatestMetadata(String clusterName, String clusterUUID) throws IOException{
         start();
         Optional<ClusterMetadataManifest> clusterMetadataManifest = getLatestClusterMetadataManifest(clusterName, clusterUUID);
         if (!clusterMetadataManifest.isPresent()) {
             throw new IllegalStateException("Latest index metadata is not present for the provided clusterUUID");
         }
-        String globalMetadataFileName = clusterMetadataManifest.get().getGlobalMetadataFileName();
+        // Fetch Global Metadata
+        Metadata metadataWithGlobalMetadata = getGlobalMetadata(clusterName, clusterUUID, clusterMetadataManifest.get());
+
+        // Fetch Index Metadata
+        Map<String, IndexMetadata> indices = getIndexMetadataMap(clusterName, clusterUUID, clusterMetadataManifest.get());
+
+        return Metadata.builder(metadataWithGlobalMetadata).indices(indices).build();
+    }
+
+    private Metadata getGlobalMetadata(String clusterName, String clusterUUID, ClusterMetadataManifest clusterMetadataManifest) {
+        String globalMetadataFileName = clusterMetadataManifest.getGlobalMetadataFileName();
         try {
-            String[] splitPath = globalMetadataFileName.split("/");
-            return BlobStoreRepository.GLOBAL_METADATA_FORMAT.read(
-                globalMetadataContainer(clusterName, clusterUUID),
-                splitPath[splitPath.length - 1],
-                blobStoreRepository.getNamedXContentRegistry()
-            );
+            // Fetch Global metadata
+            if(globalMetadataFileName != null) {
+                String[] splitPath = globalMetadataFileName.split("/");
+                return BlobStoreRepository.GLOBAL_METADATA_FORMAT.read(
+                    globalMetadataContainer(clusterName, clusterUUID),
+                    splitPath[splitPath.length - 1],
+                    blobStoreRepository.getNamedXContentRegistry()
+                );
+            } else {
+                return Metadata.EMPTY_METADATA;
+            }
         } catch (IOException e) {
             throw new IllegalStateException(
                 String.format(Locale.ROOT, "Error while downloading Global Metadata - %s", globalMetadataFileName),

server/src/main/java/org/opensearch/index/recovery/RemoteStoreRestoreService.java

@@ -141,7 +141,7 @@ public RemoteRestoreResult restore(
             || restoreClusterUUID.isBlank()) == false;
         if (metadataFromRemoteStore) {
             try {
-                remoteClusterStateService.getLatestIndexMetadata(currentState.getClusterName().value(), restoreClusterUUID)
+                remoteClusterStateService.getLatestMetadata(currentState.getClusterName().value(), restoreClusterUUID).getIndices()
                     .values()
                     .forEach(indexMetadata -> {
                         indexMetadataMap.put(indexMetadata.getIndex().getName(), new Tuple<>(true, indexMetadata));

server/src/test/java/org/opensearch/gateway/remote/RemoteClusterStateServiceTests.java

@@ -405,7 +405,7 @@ public void testReadLatestMetadataManifestSuccessButNoIndexMetadata() throws IOE
 
         remoteClusterStateService.start();
         assertEquals(
-            remoteClusterStateService.getLatestIndexMetadata(clusterState.getClusterName().value(), clusterState.metadata().clusterUUID())
+            remoteClusterStateService.getLatestMetadata(clusterState.getClusterName().value(), clusterState.metadata().clusterUUID()).getIndices()
                 .size(),
             0
         );
@@ -433,10 +433,10 @@ public void testReadLatestMetadataManifestSuccessButIndexMetadataFetchIOExceptio
         remoteClusterStateService.start();
         Exception e = assertThrows(
             IllegalStateException.class,
-            () -> remoteClusterStateService.getLatestIndexMetadata(
+            () -> remoteClusterStateService.getLatestMetadata(
                 clusterState.getClusterName().value(),
                 clusterState.metadata().clusterUUID()
-            )
+            ).getIndices()
         );
         assertEquals(e.getMessage(), "Error while downloading IndexMetadata - " + uploadedIndexMetadata.getUploadedFilename());
     }
@@ -493,7 +493,7 @@ public void testReadGlobalMetadata() throws IOException {
         Metadata expactedMetadata = Metadata.builder().persistentSettings(Settings.builder().put("readonly", true).build()).build();
         mockBlobContainerForGlobalMetadata(mockBlobStoreObjects(), expectedManifest, expactedMetadata);
 
-        Metadata metadata = remoteClusterStateService.getGlobalMetadata(
+        Metadata metadata = remoteClusterStateService.getLatestMetadata(
             clusterState.getClusterName().value(),
             clusterState.metadata().clusterUUID()
         );
@@ -529,7 +529,7 @@ public void testReadGlobalMetadataIOException() throws IOException {
         remoteClusterStateService.start();
         Exception e = assertThrows(
             IllegalStateException.class,
-            () -> remoteClusterStateService.getGlobalMetadata(clusterState.getClusterName().value(), clusterState.metadata().clusterUUID())
+            () -> remoteClusterStateService.getLatestMetadata(clusterState.getClusterName().value(), clusterState.metadata().clusterUUID())
         );
         assertEquals(e.getMessage(), "Error while downloading Global Metadata - " + globalIndexMetadataName);
     }
@@ -581,10 +581,10 @@ public void testReadLatestIndexMetadataSuccess() throws IOException {
 
         mockBlobContainer(mockBlobStoreObjects(), expectedManifest, Map.of(index.getUUID(), indexMetadata));
 
-        Map<String, IndexMetadata> indexMetadataMap = remoteClusterStateService.getLatestIndexMetadata(
+        Map<String, IndexMetadata> indexMetadataMap = remoteClusterStateService.getLatestMetadata(
             clusterState.getClusterName().value(),
             clusterState.metadata().clusterUUID()
-        );
+        ).getIndices();
 
         assertEquals(indexMetadataMap.size(), 1);
         assertEquals(indexMetadataMap.get(index.getUUID()).getIndex().getName(), index.getName());