Optimise memory for rest cluster health calls with inline shard aggre…

…gations for levels cluster and indices.

Signed-off-by: Swetha Guptha <gupthasg@amazon.com>

CHANGELOG.md

@@ -48,6 +48,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add prefix support to hashed prefix & infix path types on remote store ([#15557](https://github.com/opensearch-project/OpenSearch/pull/15557))
 - Optimise snapshot deletion to speed up snapshot deletion and creation ([#15568](https://github.com/opensearch-project/OpenSearch/pull/15568))
 - [Remote Publication] Added checksum validation for cluster state behind a cluster setting ([#15218](https://github.com/opensearch-project/OpenSearch/pull/15218))
+- Cluster health API memory optimisation based on health level ([#15492](https://github.com/opensearch-project/OpenSearch/pull/15492))
 
 ### Dependencies
 - Bump `netty` from 4.1.111.Final to 4.1.112.Final ([#15081](https://github.com/opensearch-project/OpenSearch/pull/15081))

server/src/internalClusterTest/java/org/opensearch/cluster/ClusterHealthIT.java

@@ -37,6 +37,8 @@
 import org.opensearch.action.support.IndicesOptions;
 import org.opensearch.action.support.PlainActionFuture;
 import org.opensearch.cluster.health.ClusterHealthStatus;
+import org.opensearch.cluster.health.ClusterIndexHealth;
+import org.opensearch.cluster.health.ClusterShardHealth;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.cluster.routing.UnassignedInfo;
 import org.opensearch.cluster.service.ClusterService;
@@ -49,6 +51,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import static org.opensearch.test.hamcrest.OpenSearchAssertions.assertAcked;
@@ -439,4 +442,154 @@ public void clusterStateProcessed(String source, ClusterState oldState, ClusterS
             completionFuture.actionGet(TimeValue.timeValueSeconds(30));
         }
     }
+
+    public void testHealthAtLevelParamEqualsClusterIsHonoured() {
+        createIndex(
+            "test1",
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1).put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0).build()
+        );
+        ensureGreen();
+        ClusterHealthResponse healthResponse = client().admin()
+            .cluster()
+            .prepareHealth()
+            .setApplyLevelAtTransportLayer(true)
+            .execute()
+            .actionGet();
+        assertEquals(ClusterHealthStatus.GREEN, healthResponse.getStatus());
+        assertTrue(healthResponse.getIndices().isEmpty());
+        assertEquals(1, healthResponse.getActiveShards());
+        assertEquals(1, healthResponse.getActivePrimaryShards());
+        assertEquals(0, healthResponse.getUnassignedShards());
+        assertEquals(0, healthResponse.getInitializingShards());
+        assertEquals(0, healthResponse.getRelocatingShards());
+        assertEquals(0, healthResponse.getDelayedUnassignedShards());
+    }
+
+    public void testHealthAtLevelParamEqualIndicesIsHonoured() {
+        createIndex(
+            "test1",
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1).put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0).build()
+        );
+        ensureGreen();
+        ClusterHealthResponse healthResponse = client().admin()
+            .cluster()
+            .prepareHealth()
+            .setLevel("indices")
+            .setApplyLevelAtTransportLayer(true)
+            .execute()
+            .actionGet();
+        assertEquals(ClusterHealthStatus.GREEN, healthResponse.getStatus());
+
+        assertEquals(1, healthResponse.getActiveShards());
+        assertEquals(1, healthResponse.getActivePrimaryShards());
+        assertEquals(0, healthResponse.getUnassignedShards());
+        assertEquals(0, healthResponse.getInitializingShards());
+        assertEquals(0, healthResponse.getRelocatingShards());
+        assertEquals(0, healthResponse.getDelayedUnassignedShards());
+
+        Map<String, ClusterIndexHealth> indices = healthResponse.getIndices();
+        assertFalse(indices.isEmpty());
+        assertEquals(1, indices.size());
+        for (Map.Entry<String, ClusterIndexHealth> indicesHealth : indices.entrySet()) {
+            String indexName = indicesHealth.getKey();
+            assertEquals("test1", indexName);
+            ClusterIndexHealth indicesHealthValue = indicesHealth.getValue();
+            assertEquals(1, indicesHealthValue.getActiveShards());
+            assertEquals(1, indicesHealthValue.getActivePrimaryShards());
+            assertEquals(0, indicesHealthValue.getInitializingShards());
+            assertEquals(0, indicesHealthValue.getUnassignedShards());
+            assertEquals(0, indicesHealthValue.getDelayedUnassignedShards());
+            assertEquals(0, indicesHealthValue.getRelocatingShards());
+            assertEquals(ClusterHealthStatus.GREEN, indicesHealthValue.getStatus());
+            assertTrue(indicesHealthValue.getShards().isEmpty());
+        }
+    }
+
+    public void testHealthAtLevelParamEqualShardsIsHonoured() {
+        createIndex(
+            "test1",
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1).put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 1).build()
+        );
+        ensureGreen(TimeValue.timeValueSeconds(120), "test1");
+        createIndex(
+            "test2",
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1).put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 1).build()
+        );
+        ensureGreen(TimeValue.timeValueSeconds(120));
+        client().admin()
+            .indices()
+            .prepareUpdateSettings()
+            .setIndices("test2")
+            .setSettings(Settings.builder().put("index.number_of_replicas", 2).build())
+            .execute()
+            .actionGet();
+        ClusterHealthResponse healthResponse = client().admin()
+            .cluster()
+            .prepareHealth()
+            .setLevel("shards")
+            .setApplyLevelAtTransportLayer(true)
+            .execute()
+            .actionGet();
+        assertEquals(ClusterHealthStatus.YELLOW, healthResponse.getStatus());
+
+        assertEquals(4, healthResponse.getActiveShards());
+        assertEquals(2, healthResponse.getActivePrimaryShards());
+        assertEquals(1, healthResponse.getUnassignedShards());
+        assertEquals(0, healthResponse.getInitializingShards());
+        assertEquals(0, healthResponse.getRelocatingShards());
+        assertEquals(0, healthResponse.getDelayedUnassignedShards());
+
+        Map<String, ClusterIndexHealth> indices = healthResponse.getIndices();
+        assertFalse(indices.isEmpty());
+        assertEquals(2, indices.size());
+        for (Map.Entry<String, ClusterIndexHealth> indicesHealth : indices.entrySet()) {
+            String indexName = indicesHealth.getKey();
+            boolean indexHasMoreReplicas = indexName.equals("test2");
+            ClusterIndexHealth indicesHealthValue = indicesHealth.getValue();
+            assertEquals(2, indicesHealthValue.getActiveShards());
+            assertEquals(1, indicesHealthValue.getActivePrimaryShards());
+            assertEquals(0, indicesHealthValue.getInitializingShards());
+            assertEquals(indexHasMoreReplicas ? 1 : 0, indicesHealthValue.getUnassignedShards());
+            assertEquals(0, indicesHealthValue.getDelayedUnassignedShards());
+            assertEquals(0, indicesHealthValue.getRelocatingShards());
+            assertEquals(indexHasMoreReplicas ? ClusterHealthStatus.YELLOW : ClusterHealthStatus.GREEN, indicesHealthValue.getStatus());
+            Map<Integer, ClusterShardHealth> shards = indicesHealthValue.getShards();
+            assertFalse(shards.isEmpty());
+            assertEquals(1, shards.size());
+            for (Map.Entry<Integer, ClusterShardHealth> shardHealth : shards.entrySet()) {
+                ClusterShardHealth clusterShardHealth = shardHealth.getValue();
+                assertEquals(2, clusterShardHealth.getActiveShards());
+                assertEquals(indexHasMoreReplicas ? 1 : 0, clusterShardHealth.getUnassignedShards());
+                assertEquals(0, clusterShardHealth.getDelayedUnassignedShards());
+                assertEquals(0, clusterShardHealth.getRelocatingShards());
+                assertEquals(0, clusterShardHealth.getInitializingShards());
+                assertTrue(clusterShardHealth.isPrimaryActive());
+                assertEquals(indexHasMoreReplicas ? ClusterHealthStatus.YELLOW : ClusterHealthStatus.GREEN, clusterShardHealth.getStatus());
+            }
+        }
+    }
+
+    public void testHealthAtLevelParamEqualsAttributeAwarenessIsHonoured() {
+        createIndex(
+            "test1",
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1).put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0).build()
+        );
+        ensureGreen();
+        ClusterHealthResponse healthResponse = client().admin()
+            .cluster()
+            .prepareHealth()
+            .setLevel("awareness_attributes")
+            .setApplyLevelAtTransportLayer(true)
+            .execute()
+            .actionGet();
+        assertEquals(ClusterHealthStatus.GREEN, healthResponse.getStatus());
+        assertTrue(healthResponse.getIndices().isEmpty());
+        assertNotNull(healthResponse.getClusterAwarenessHealth());
+        assertEquals(1, healthResponse.getActiveShards());
+        assertEquals(1, healthResponse.getActivePrimaryShards());
+        assertEquals(0, healthResponse.getUnassignedShards());
+        assertEquals(0, healthResponse.getInitializingShards());
+        assertEquals(0, healthResponse.getRelocatingShards());
+        assertEquals(0, healthResponse.getDelayedUnassignedShards());
+    }
 }

server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthRequest.java

@@ -76,6 +76,17 @@ public class ClusterHealthRequest extends ClusterManagerNodeReadRequest<ClusterH
      */
     private Level level = Level.CLUSTER;
 
+    /**
+     * This flag will be used by the TransportClusterHealthAction to decide if indices/shards info is required in the ClusterHealthResponse or not.
+     * When the flag is disabled - indices/shard info will be returned in ClusterHealthResponse regardless of the health level requested.
+     * When the flag is enabled - indices/shards info will be set according to health level requested.
+     *                  For Level.CLUSTER (or) LevelAWARENESS_ATTRIBUTES - information on indices/shards will NOT be returned to the transport client
+     *                  For Level.INDICES - information on indices will be returned to the transport client.
+     *                  For Level.SHARDS - information on indices and shards will be returned to the transport client
+     * By default, the flag is disabled.
+     */
+    private boolean applyLevelAtTransportLayer = false;
+
     public ClusterHealthRequest() {}
 
     public ClusterHealthRequest(String... indices) {
@@ -104,6 +115,9 @@ public ClusterHealthRequest(StreamInput in) throws IOException {
         if (in.getVersion().onOrAfter(Version.V_2_6_0)) {
             ensureNodeWeighedIn = in.readBoolean();
         }
+        if (in.getVersion().onOrAfter(Version.V_3_0_0)) {
+            applyLevelAtTransportLayer = in.readBoolean();
+        }
     }
 
     @Override
@@ -139,6 +153,9 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getVersion().onOrAfter(Version.V_2_6_0)) {
             out.writeBoolean(ensureNodeWeighedIn);
         }
+        if (out.getVersion().onOrAfter(Version.V_3_0_0)) {
+            out.writeBoolean(applyLevelAtTransportLayer);
+        }
     }
 
     @Override
@@ -337,6 +354,14 @@ public final boolean ensureNodeWeighedIn() {
         return ensureNodeWeighedIn;
     }
 
+    public boolean isApplyLevelAtTransportLayer() {
+        return applyLevelAtTransportLayer;
+    }
+
+    public void setApplyLevelAtTransportLayer(boolean applyLevelAtTransportLayer) {
+        this.applyLevelAtTransportLayer = applyLevelAtTransportLayer;
+    }
+
     @Override
     public ActionRequestValidationException validate() {
         if (level.equals(Level.AWARENESS_ATTRIBUTES) && indices.length > 0) {

server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthRequestBuilder.java

@@ -171,4 +171,9 @@ public final ClusterHealthRequestBuilder setEnsureNodeWeighedIn(boolean ensureNo
         request.ensureNodeWeighedIn(ensureNodeCommissioned);
         return this;
     }
+
+    public ClusterHealthRequestBuilder setApplyLevelAtTransportLayer(boolean applyLevelAtTransportLayer) {
+        request.setApplyLevelAtTransportLayer(applyLevelAtTransportLayer);
+        return this;
+    }
 }

server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthResponse.java

@@ -237,6 +237,26 @@ public ClusterHealthResponse(
         this.clusterHealthStatus = clusterStateHealth.getStatus();
     }
 
+    public ClusterHealthResponse(
+        String clusterName,
+        String[] concreteIndices,
+        ClusterHealthRequest clusterHealthRequest,
+        ClusterState clusterState,
+        int numberOfPendingTasks,
+        int numberOfInFlightFetch,
+        TimeValue taskMaxWaitingTime
+    ) {
+        this.clusterName = clusterName;
+        this.numberOfPendingTasks = numberOfPendingTasks;
+        this.numberOfInFlightFetch = numberOfInFlightFetch;
+        this.taskMaxWaitingTime = taskMaxWaitingTime;
+        this.clusterStateHealth = clusterHealthRequest.isApplyLevelAtTransportLayer()
+            ? new ClusterStateHealth(clusterState, concreteIndices, clusterHealthRequest.level())
+            : new ClusterStateHealth(clusterState, concreteIndices);
+        this.clusterHealthStatus = clusterStateHealth.getStatus();
+        this.delayedUnassignedShards = clusterStateHealth.getDelayedUnassignedShards();
+    }
+
     // Awareness Attribute health
     public ClusterHealthResponse(
         String clusterName,
@@ -261,6 +281,29 @@ public ClusterHealthResponse(
         this.clusterAwarenessHealth = new ClusterAwarenessHealth(clusterState, clusterSettings, awarenessAttributeName);
     }
 
+    public ClusterHealthResponse(
+        String clusterName,
+        ClusterHealthRequest clusterHealthRequest,
+        ClusterState clusterState,
+        ClusterSettings clusterSettings,
+        String[] concreteIndices,
+        String awarenessAttributeName,
+        int numberOfPendingTasks,
+        int numberOfInFlightFetch,
+        TimeValue taskMaxWaitingTime
+    ) {
+        this(
+            clusterName,
+            concreteIndices,
+            clusterHealthRequest,
+            clusterState,
+            numberOfPendingTasks,
+            numberOfInFlightFetch,
+            taskMaxWaitingTime
+        );
+        this.clusterAwarenessHealth = new ClusterAwarenessHealth(clusterState, clusterSettings, awarenessAttributeName);
+    }
+
     /**
      * For XContent Parser and serialization tests
      */

server/src/main/java/org/opensearch/action/admin/cluster/health/TransportClusterHealthAction.java

@@ -52,7 +52,6 @@
 import org.opensearch.cluster.metadata.ProcessClusterEventTimeoutException;
 import org.opensearch.cluster.node.DiscoveryNode;
 import org.opensearch.cluster.routing.NodeWeighedAwayException;
-import org.opensearch.cluster.routing.UnassignedInfo;
 import org.opensearch.cluster.routing.WeightedRoutingUtils;
 import org.opensearch.cluster.routing.allocation.AllocationService;
 import org.opensearch.cluster.service.ClusterService;
@@ -487,7 +486,12 @@ private ClusterHealthResponse clusterHealth(
         TimeValue pendingTaskTimeInQueue
     ) {
         if (logger.isTraceEnabled()) {
-            logger.trace("Calculating health based on state version [{}]", clusterState.version());
+            logger.trace(
+                "Calculating health based on state version [{}] for health level [{}] and applyLevelAtTransportLayer set to [{}]",
+                clusterState.version(),
+                request.level(),
+                request.isApplyLevelAtTransportLayer()
+            );
         }
 
         String[] concreteIndices;
@@ -496,13 +500,13 @@ private ClusterHealthResponse clusterHealth(
             concreteIndices = clusterState.getMetadata().getConcreteAllIndices();
             return new ClusterHealthResponse(
                 clusterState.getClusterName().value(),
+                request,
                 clusterState,
                 clusterService.getClusterSettings(),
                 concreteIndices,
                 awarenessAttribute,
                 numberOfPendingTasks,
                 numberOfInFlightFetch,
-                UnassignedInfo.getNumberOfDelayedUnassigned(clusterState),
                 pendingTaskTimeInQueue
             );
         }
@@ -514,10 +518,10 @@ private ClusterHealthResponse clusterHealth(
             ClusterHealthResponse response = new ClusterHealthResponse(
                 clusterState.getClusterName().value(),
                 Strings.EMPTY_ARRAY,
+                request,
                 clusterState,
                 numberOfPendingTasks,
                 numberOfInFlightFetch,
-                UnassignedInfo.getNumberOfDelayedUnassigned(clusterState),
                 pendingTaskTimeInQueue
             );
             response.setStatus(ClusterHealthStatus.RED);
@@ -527,10 +531,10 @@ private ClusterHealthResponse clusterHealth(
         return new ClusterHealthResponse(
             clusterState.getClusterName().value(),
             concreteIndices,
+            request,
             clusterState,
             numberOfPendingTasks,
             numberOfInFlightFetch,
-            UnassignedInfo.getNumberOfDelayedUnassigned(clusterState),
             pendingTaskTimeInQueue
         );
     }

server/src/main/java/org/opensearch/action/admin/cluster/stats/TransportClusterStatsAction.java

@@ -34,6 +34,7 @@
 
 import org.apache.lucene.store.AlreadyClosedException;
 import org.opensearch.action.FailedNodeException;
+import org.opensearch.action.admin.cluster.health.ClusterHealthRequest;
 import org.opensearch.action.admin.cluster.node.info.NodeInfo;
 import org.opensearch.action.admin.cluster.node.stats.NodeStats;
 import org.opensearch.action.admin.indices.stats.CommonStats;
@@ -209,7 +210,7 @@ protected ClusterStatsNodeResponse nodeOperation(ClusterStatsNodeRequest nodeReq
 
         ClusterHealthStatus clusterStatus = null;
         if (clusterService.state().nodes().isLocalNodeElectedClusterManager()) {
-            clusterStatus = new ClusterStateHealth(clusterService.state()).getStatus();
+            clusterStatus = new ClusterStateHealth(clusterService.state(), ClusterHealthRequest.Level.CLUSTER).getStatus();
         }
 
         return new ClusterStatsNodeResponse(