Fix GetSnapshots to not return non-existent snapshots with ignore_una…

…vailable=true (#6839)

* Fix bug for Get Snapshot API to return correct response when getting a non-existing snapshot (#6820)

Signed-off-by: Gao Binlong <gbinlong@amazon.com>

* modify change log

Signed-off-by: Gao Binlong <gbinlong@amazon.com>

* Modify changelog

Signed-off-by: Gao Binlong <gbinlong@amazon.com>

---------

Signed-off-by: Gao Binlong <gbinlong@amazon.com>

CHANGELOG.md

@@ -130,8 +130,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Added equals/hashcode for named DocValueFormat.DateTime inner class ([#6357](https://github.com/opensearch-project/OpenSearch/pull/6357))
 - Fixed bug for searchable snapshot to take 'base_path' of blob into account ([#6558](https://github.com/opensearch-project/OpenSearch/pull/6558))
 - Fix fuzziness validation ([#5805](https://github.com/opensearch-project/OpenSearch/pull/5805))
+- Fix GetSnapshots to not return non-existent snapshots with ignore_unavailable=true ([#6839](https://github.com/opensearch-project/OpenSearch/pull/6839))
 
 ### Security
 
 [Unreleased 3.0]: https://github.com/opensearch-project/OpenSearch/compare/2.x...HEAD
-[Unreleased 2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.5...2.x
+[Unreleased 2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.5...2.x

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

@@ -379,6 +379,17 @@ public void testGetSnapshotsRequest() throws Exception {
             .get();
         assertEquals(1, getSnapshotsResponse.getSnapshots().size());
         assertEquals("snap-on-empty-repo", getSnapshotsResponse.getSnapshots().get(0).snapshotId().getName());
+
+        // there is an in-progress snapshot, make sure we return empty result when getting a non-existing snapshot with setting
+        // ignore_unavailable to true
+        getSnapshotsResponse = client.admin()
+            .cluster()
+            .prepareGetSnapshots("test-repo")
+            .setIgnoreUnavailable(true)
+            .addSnapshots("non-existent-snapshot")
+            .get();
+        assertEquals(0, getSnapshotsResponse.getSnapshots().size());
+
         unblockNode(repositoryName, initialBlockedNode); // unblock node
         admin().cluster().prepareDeleteSnapshot(repositoryName, "snap-on-empty-repo").get();
 

server/src/main/java/org/opensearch/action/admin/cluster/snapshots/get/TransportGetSnapshotsAction.java

@@ -239,9 +239,11 @@ private List<SnapshotInfo> snapshots(
             repositoryName,
             snapshotIdsToIterate.stream().map(SnapshotId::getName).collect(Collectors.toList())
         );
+        // filter and incorporate the snapshots in progress
         for (SnapshotsInProgress.Entry entry : entries) {
-            snapshotSet.add(new SnapshotInfo(entry));
-            snapshotIdsToIterate.remove(entry.snapshot().getSnapshotId());
+            if (snapshotIdsToIterate.remove(entry.snapshot().getSnapshotId())) {
+                snapshotSet.add(new SnapshotInfo(entry));
+            }
         }
         // then, look in the repository
         final Repository repository = repositoriesService.repository(repositoryName);