Add unit tests for MountSnapshotStep in COLD phase (#126804)

Author: samxbr

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ilm/MountSnapshotStep.java

@@ -230,8 +230,7 @@ static Optional<String> overrideTierPreference(String phase) {
      * - index.routing.allocation.total_shards_per_node: It is likely that frozen tier has fewer nodes than the hot tier. If this setting
      * is not specifically set in the frozen tier, keeping this setting runs the risk that we will not have enough nodes to
      * allocate all the shards in the frozen tier and the user does not have any way of fixing this. For this reason, we ignore this
-     * setting when moving to frozen. We do not ignore this setting if it is specifically set in the mount searchable snapshot step
-     * of frozen tier.
+     * setting when moving to frozen. We do not ignore this setting if it is specifically set in the mount searchable snapshot step.
      */
     String[] ignoredIndexSettings() {
         ArrayList<String> ignoredSettings = new ArrayList<>();
@@ -240,6 +239,7 @@ String[] ignoredIndexSettings() {
         // if total_shards_per_node setting is specifically set for the frozen phase and not propagated from previous phase,
         // then it should not be ignored
         if (TimeseriesLifecycleType.FROZEN_PHASE.equals(this.getKey().phase()) && this.totalShardsPerNode == null) {
+            // in frozen phase only, propagated total_shards_per_node (from previous hot/cold phase) is ignored
             ignoredSettings.add(ShardsLimitAllocationDecider.INDEX_TOTAL_SHARDS_PER_NODE_SETTING.getKey());
         }
         return ignoredSettings.toArray(new String[0]);

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/MountSnapshotStepTests.java

@@ -397,7 +397,52 @@ public void testIgnoreTotalShardsPerNodeInFrozenPhase() throws Exception {
         }
     }
 
-    public void testDoNotIgnoreTotalShardsPerNodeAndReplicasIfSet() throws Exception {
+    public void testDoNotIgnorePropagatedTotalShardsPerNodeInColdPhase() throws Exception {
+        String indexName = randomAlphaOfLength(10);
+        String policyName = "test-ilm-policy";
+        Map<String, String> ilmCustom = new HashMap<>();
+        String snapshotName = indexName + "-" + policyName;
+        ilmCustom.put("snapshot_name", snapshotName);
+        String repository = "repository";
+        ilmCustom.put("snapshot_repository", repository);
+
+        IndexMetadata.Builder indexMetadataBuilder = IndexMetadata.builder(indexName)
+            .settings(settings(IndexVersion.current()).put(LifecycleSettings.LIFECYCLE_NAME, policyName))
+            .putCustom(LifecycleExecutionState.ILM_CUSTOM_METADATA_KEY, ilmCustom)
+            .numberOfShards(randomIntBetween(1, 5))
+            .numberOfReplicas(randomIntBetween(0, 5));
+        IndexMetadata indexMetadata = indexMetadataBuilder.build();
+
+        ClusterState clusterState = ClusterState.builder(emptyClusterState())
+            .metadata(Metadata.builder().put(indexMetadata, true).build())
+            .build();
+
+        try (var threadPool = createThreadPool()) {
+            final var client = getRestoreSnapshotRequestAssertingClient(
+                threadPool,
+                repository,
+                snapshotName,
+                indexName,
+                RESTORED_INDEX_PREFIX,
+                indexName,
+                new String[] { LifecycleSettings.LIFECYCLE_NAME },
+                null,
+                0
+            );
+            MountSnapshotStep step = new MountSnapshotStep(
+                new StepKey(TimeseriesLifecycleType.COLD_PHASE, randomAlphaOfLength(10), randomAlphaOfLength(10)),
+                randomStepKey(),
+                client,
+                RESTORED_INDEX_PREFIX,
+                randomStorageType(),
+                null,
+                0
+            );
+            performActionAndWait(step, indexMetadata, clusterState, null);
+        }
+    }
+
+    public void testDoNotIgnoreTotalShardsPerNodeAndReplicasIfSetInFrozenPhase() throws Exception {
         String indexName = randomAlphaOfLength(10);
         String policyName = "test-ilm-policy";
         Map<String, String> ilmCustom = new HashMap<>();
@@ -445,6 +490,54 @@ public void testDoNotIgnoreTotalShardsPerNodeAndReplicasIfSet() throws Exception
         }
     }
 
+    public void testDoNotIgnoreTotalShardsPerNodeAndReplicasIfSetInCold() throws Exception {
+        String indexName = randomAlphaOfLength(10);
+        String policyName = "test-ilm-policy";
+        Map<String, String> ilmCustom = new HashMap<>();
+        String snapshotName = indexName + "-" + policyName;
+        ilmCustom.put("snapshot_name", snapshotName);
+        String repository = "repository";
+        ilmCustom.put("snapshot_repository", repository);
+
+        IndexMetadata.Builder indexMetadataBuilder = IndexMetadata.builder(indexName)
+            .settings(settings(IndexVersion.current()).put(LifecycleSettings.LIFECYCLE_NAME, policyName))
+            .putCustom(LifecycleExecutionState.ILM_CUSTOM_METADATA_KEY, ilmCustom)
+            .numberOfShards(randomIntBetween(1, 5))
+            .numberOfReplicas(randomIntBetween(0, 5));
+        IndexMetadata indexMetadata = indexMetadataBuilder.build();
+
+        ClusterState clusterState = ClusterState.builder(emptyClusterState())
+            .metadata(Metadata.builder().put(indexMetadata, true).build())
+            .build();
+
+        final Integer totalShardsPerNode = randomTotalShardsPerNode(false);
+        final int replicas = randomIntBetween(1, 5);
+
+        try (var threadPool = createThreadPool()) {
+            final var client = getRestoreSnapshotRequestAssertingClient(
+                threadPool,
+                repository,
+                snapshotName,
+                indexName,
+                RESTORED_INDEX_PREFIX,
+                indexName,
+                new String[] { LifecycleSettings.LIFECYCLE_NAME },
+                totalShardsPerNode,
+                replicas
+            );
+            MountSnapshotStep step = new MountSnapshotStep(
+                new StepKey(TimeseriesLifecycleType.COLD_PHASE, randomAlphaOfLength(10), randomAlphaOfLength(10)),
+                randomStepKey(),
+                client,
+                RESTORED_INDEX_PREFIX,
+                randomStorageType(),
+                totalShardsPerNode,
+                replicas
+            );
+            performActionAndWait(step, indexMetadata, clusterState, null);
+        }
+    }
+
     @SuppressWarnings("unchecked")
     private NoOpClient getClientTriggeringResponse(ThreadPool threadPool, RestoreSnapshotResponse response) {
         return new NoOpClient(threadPool) {