[Searchable Snapshot] Add Relevant Error handling for Restore API with remote_snapshot. (#11840) (#12011)

* Add Relevant Error handling for Restore API with remote_snapshot.



* update comment with more revelant info.



* apply spotless check.



* Add null check



* apply spotless check.



* fix error message in test.



* apply spotless check.



---------



(cherry picked from commit 7da8628)

Signed-off-by: Rishikesh1159 <rishireddy1159@gmail.com>
Signed-off-by: Rishikesh Pasham <62345295+Rishikesh1159@users.noreply.github.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: opensearch-trigger-bot[bot]

server/src/internalClusterTest/java/org/opensearch/snapshots/SearchableSnapshotIT.java

@@ -54,6 +54,7 @@
 import static org.opensearch.action.admin.cluster.node.stats.NodesStatsRequest.Metric.FS;
 import static org.opensearch.core.common.util.CollectionUtils.iterableAsArrayList;
 import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.is;
@@ -722,6 +723,47 @@ public void testDefaultShardPreference() throws Exception {
         }
     }
 
+    public void testRestoreSearchableSnapshotWithIndexStoreTypeThrowsException() throws Exception {
+        final String snapshotName = "test-snap";
+        final String repoName = "test-repo";
+        final String indexName1 = "test-idx-1";
+        final int numReplicasIndex1 = randomIntBetween(1, 4);
+        final Client client = client();
+
+        internalCluster().ensureAtLeastNumDataNodes(numReplicasIndex1 + 1);
+        createIndexWithDocsAndEnsureGreen(numReplicasIndex1, 100, indexName1);
+
+        createRepositoryWithSettings(null, repoName);
+        takeSnapshot(client, snapshotName, repoName, indexName1);
+        deleteIndicesAndEnsureGreen(client, indexName1);
+
+        internalCluster().ensureAtLeastNumSearchNodes(numReplicasIndex1 + 1);
+
+        // set "index.store.type" to "remote_snapshot" in index settings of restore API and assert appropriate exception with error message
+        // is thrown.
+        final SnapshotRestoreException error = expectThrows(
+            SnapshotRestoreException.class,
+            () -> client.admin()
+                .cluster()
+                .prepareRestoreSnapshot(repoName, snapshotName)
+                .setRenamePattern("(.+)")
+                .setRenameReplacement("$1-copy")
+                .setIndexSettings(
+                    Settings.builder()
+                        .put(IndexModule.INDEX_STORE_TYPE_SETTING.getKey(), RestoreSnapshotRequest.StorageType.REMOTE_SNAPSHOT)
+                )
+                .setWaitForCompletion(true)
+                .execute()
+                .actionGet()
+        );
+        assertThat(
+            error.getMessage(),
+            containsString(
+                "cannot restore remote snapshot with index settings \"index.store.type\" set to \"remote_snapshot\". Instead use \"storage_type\": \"remote_snapshot\" as argument to restore."
+            )
+        );
+    }
+
     /**
      * Asserts the cache folder count to match the number of shards and the number of indices within the cache folder
      * as provided.

server/src/main/java/org/opensearch/snapshots/RestoreService.java

@@ -122,6 +122,7 @@
 import static org.opensearch.cluster.metadata.IndexMetadata.SETTING_VERSION_UPGRADED;
 import static org.opensearch.common.util.FeatureFlags.SEARCHABLE_SNAPSHOT_EXTENDED_COMPATIBILITY;
 import static org.opensearch.common.util.set.Sets.newHashSet;
+import static org.opensearch.index.IndexModule.INDEX_STORE_TYPE_SETTING;
 import static org.opensearch.index.store.remote.directory.RemoteSnapshotDirectory.SEARCHABLE_SNAPSHOT_EXTENDED_COMPATIBILITY_MINIMUM_VERSION;
 import static org.opensearch.index.store.remote.filecache.FileCache.DATA_TO_FILE_CACHE_SIZE_RATIO_SETTING;
 import static org.opensearch.node.Node.NODE_SEARCH_CACHE_SIZE_SETTING;
@@ -227,6 +228,16 @@ public RestoreService(
      */
     public void restoreSnapshot(final RestoreSnapshotRequest request, final ActionListener<RestoreCompletionResponse> listener) {
         try {
+            // Setting INDEX_STORE_TYPE_SETTING as REMOTE_SNAPSHOT is intended to be a system-managed index setting that is configured when
+            // restoring a snapshot and should not be manually set by user.
+            String storeTypeSetting = request.indexSettings().get(INDEX_STORE_TYPE_SETTING.getKey());
+            if (storeTypeSetting != null && storeTypeSetting.equals(RestoreSnapshotRequest.StorageType.REMOTE_SNAPSHOT.toString())) {
+                throw new SnapshotRestoreException(
+                    request.repository(),
+                    request.snapshot(),
+                    "cannot restore remote snapshot with index settings \"index.store.type\" set to \"remote_snapshot\". Instead use \"storage_type\": \"remote_snapshot\" as argument to restore."
+                );
+            }
             // Read snapshot info and metadata from the repository
             final String repositoryName = request.repository();
             Repository repository = repositoriesService.repository(repositoryName);