[Backport 2.x] Fix remote cluster restore for data stream

server/src/internalClusterTest/java/org/opensearch/action/admin/indices/datastream/DataStreamTestCase.java

@@ -37,6 +37,7 @@ public AcknowledgedResponse createDataStream(String name) throws Exception {
         CreateDataStreamAction.Request request = new CreateDataStreamAction.Request(name);
         AcknowledgedResponse response = client().admin().indices().createDataStream(request).get();
         assertThat(response.isAcknowledged(), is(true));
+        performRemoteStoreTestAction();
         return response;
     }
 
@@ -67,6 +68,7 @@ public RolloverResponse rolloverDataStream(String name) throws Exception {
         RolloverResponse response = client().admin().indices().rolloverIndex(request).get();
         assertThat(response.isAcknowledged(), is(true));
         assertThat(response.isRolledOver(), is(true));
+        performRemoteStoreTestAction();
         return response;
     }
 
@@ -109,5 +111,4 @@ public AcknowledgedResponse deleteIndexTemplate(String name) throws Exception {
         assertThat(response.isAcknowledged(), is(true));
         return response;
     }
-
 }

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteStoreClusterStateRestoreIT.java

@@ -9,6 +9,7 @@
 package org.opensearch.remotestore;
 
 import org.opensearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
+import org.opensearch.action.admin.indices.datastream.DataStreamRolloverIT;
 import org.opensearch.action.admin.indices.settings.put.UpdateSettingsRequest;
 import org.opensearch.action.admin.indices.template.put.PutIndexTemplateRequest;
 import org.opensearch.cluster.ClusterState;
@@ -291,6 +292,14 @@ private void validateCurrentMetadata() throws Exception {
         });
     }
 
+    public void testDataStreamPostRemoteStateRestore() throws Exception {
+        new DataStreamRolloverIT() {
+            protected boolean triggerRemoteStateRestore() {
+                return true;
+            }
+        }.testDataStreamRollover();
+    }
+
     public void testFullClusterRestoreGlobalMetadata() throws Exception {
         int shardCount = randomIntBetween(1, 2);
         int replicaCount = 1;

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

@@ -732,7 +732,10 @@ public Metadata getLatestMetadata(String clusterName, String clusterUUID) {
         // Fetch Index Metadata
         Map<String, IndexMetadata> indices = getIndexMetadataMap(clusterName, clusterUUID, clusterMetadataManifest.get());
 
-        return Metadata.builder(globalMetadata).indices(indices).build();
+        Map<String, IndexMetadata> indexMetadataMap = new HashMap<>();
+        indices.values().forEach(indexMetadata -> { indexMetadataMap.put(indexMetadata.getIndex().getName(), indexMetadata); });
+
+        return Metadata.builder(globalMetadata).indices(indexMetadataMap).build();
     }
 
     private Metadata getGlobalMetadata(String clusterName, String clusterUUID, ClusterMetadataManifest clusterMetadataManifest) {

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

@@ -826,9 +826,9 @@ public void testReadLatestIndexMetadataSuccess() throws IOException {
         ).getIndices();
 
         assertEquals(indexMetadataMap.size(), 1);
-        assertEquals(indexMetadataMap.get(index.getUUID()).getIndex().getName(), index.getName());
-        assertEquals(indexMetadataMap.get(index.getUUID()).getNumberOfShards(), indexMetadata.getNumberOfShards());
-        assertEquals(indexMetadataMap.get(index.getUUID()).getNumberOfReplicas(), indexMetadata.getNumberOfReplicas());
+        assertEquals(indexMetadataMap.get(index.getName()).getIndex().getName(), index.getName());
+        assertEquals(indexMetadataMap.get(index.getName()).getNumberOfShards(), indexMetadata.getNumberOfShards());
+        assertEquals(indexMetadataMap.get(index.getName()).getNumberOfReplicas(), indexMetadata.getNumberOfReplicas());
     }
 
     public void testMarkLastStateAsCommittedSuccess() throws IOException {

test/framework/src/main/java/org/opensearch/test/InternalTestCluster.java

@@ -1871,6 +1871,18 @@ public void stopAllNodes() {
         }
     }
 
+    /**
+     * Replace all nodes by stopping all current node and starting new node.
+     * Used for remote store test cases, where remote state is restored.
+     */
+    public void resetCluster() {
+        int totalClusterManagerNodes = numClusterManagerNodes();
+        int totalDataNodes = numDataNodes();
+        stopAllNodes();
+        startClusterManagerOnlyNodes(totalClusterManagerNodes);
+        startDataOnlyNodes(totalDataNodes);
+    }
+
     private synchronized void startAndPublishNodesAndClients(List<NodeAndClient> nodeAndClients) {
         if (nodeAndClients.size() > 0) {
             final int newClusterManagers = (int) nodeAndClients.stream()

test/framework/src/main/java/org/opensearch/test/OpenSearchIntegTestCase.java

@@ -796,6 +796,30 @@ protected Settings featureFlagSettings() {
         return featureSettings.build();
     }
 
+    /**
+     * Represent if it needs to trigger remote state restore or not.
+     * For tests with remote store enabled domain, it will be overridden to true.
+     *
+     * @return if needs to perform remote state restore or not
+     */
+    protected boolean triggerRemoteStateRestore() {
+        return false;
+    }
+
+    /**
+     * For tests with remote cluster state, it will reset the cluster and cluster state will be
+     * restored from remote.
+     */
+    protected void performRemoteStoreTestAction() {
+        if (triggerRemoteStateRestore()) {
+            String clusterUUIDBefore = clusterService().state().metadata().clusterUUID();
+            internalCluster().resetCluster();
+            String clusterUUIDAfter = clusterService().state().metadata().clusterUUID();
+            // assertion that UUID is changed post restore.
+            assertFalse(clusterUUIDBefore.equals(clusterUUIDAfter));
+        }
+    }
+
     /**
      * Creates one or more indices and asserts that the indices are acknowledged. If one of the indices
      * already exists this method will fail and wipe all the indices created so far.