skip zone awareness when auto-expand set to all

CHANGELOG.md

@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Implement WithFieldName interface in ValuesSourceAggregationBuilder & FieldSortBuilder ([#15916](https://github.com/opensearch-project/OpenSearch/pull/15916))
 - Add successfulSearchShardIndices in searchRequestContext ([#15967](https://github.com/opensearch-project/OpenSearch/pull/15967))
 - Remove identity-related feature flagged code from the RestController ([#15430](https://github.com/opensearch-project/OpenSearch/pull/15430))
+- Skip zone awareness when auto-expand set to all ([#16031](https://github.com/opensearch-project/OpenSearch/pull/16031))
 
 ### Dependencies
 - Bump `com.azure:azure-identity` from 1.13.0 to 1.13.2 ([#15578](https://github.com/opensearch-project/OpenSearch/pull/15578))

server/src/internalClusterTest/java/org/opensearch/cluster/allocation/AwarenessAllocationIT.java

@@ -504,4 +504,68 @@ public void testThreeZoneOneReplicaWithForceZoneValueAndLoadAwareness() throws E
         assertThat(clusterState.getRoutingNodes().shardsWithState(STARTED).size(), equalTo(2 * numOfShards * (numOfReplica + 1)));
         assertThat(health.isTimedOut(), equalTo(false));
     }
+
+    public void testAwarenessZonesWithAutoExpand() {
+        Settings commonSettings = Settings.builder()
+            .put(AwarenessReplicaBalance.CLUSTER_ROUTING_ALLOCATION_AWARENESS_BALANCE_SETTING.getKey(), true)
+            .put(AwarenessAllocationDecider.CLUSTER_ROUTING_ALLOCATION_AWARENESS_FORCE_GROUP_SETTING.getKey() + "zone.values", "a")
+            .put(AwarenessAllocationDecider.CLUSTER_ROUTING_ALLOCATION_AWARENESS_ATTRIBUTE_SETTING.getKey(), "zone")
+            .build();
+
+        logger.info("--> starting 2 nodes on same zone");
+        List<String> nodes = internalCluster().startNodes(
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build()
+        );
+        String A = nodes.get(0);
+        String B = nodes.get(1);
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("2").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        createIndex(
+            "test",
+            Settings.builder()
+                .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 2)
+                .put(IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS, "0-all")
+                .build()
+        );
+
+        if (randomBoolean()) {
+            assertAcked(client().admin().indices().prepareClose("test"));
+        }
+
+        logger.info("--> waiting for shards to be allocated");
+        health = client().admin()
+            .cluster()
+            .prepareHealth()
+            .setIndices("test")
+            .setWaitForEvents(Priority.LANGUID)
+            .setWaitForGreenStatus()
+            .setWaitForNoRelocatingShards(true)
+            .execute()
+            .actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ClusterState clusterState = client().admin().cluster().prepareState().execute().actionGet().getState();
+        assertThat(clusterState.getRoutingNodes().shardsWithState(STARTED).size(), equalTo(4));
+
+        final Map<String, Integer> counts = new HashMap<>();
+        int replicaCount = 0;
+
+        for (IndexRoutingTable indexRoutingTable : clusterState.routingTable()) {
+            for (IndexShardRoutingTable indexShardRoutingTable : indexRoutingTable) {
+                for (ShardRouting shardRouting : indexShardRoutingTable) {
+                    if (shardRouting.primary()) {
+                        replicaCount++;
+                    }
+                    counts.merge(clusterState.nodes().get(shardRouting.currentNodeId()).getName(), 1, Integer::sum);
+                }
+            }
+        }
+        assertThat(counts.get(A), anyOf(equalTo(1), equalTo(2)));
+        assertThat(counts.get(B), anyOf(equalTo(1), equalTo(2)));
+        assertThat(replicaCount, equalTo(2));
+    }
 }

server/src/main/java/org/opensearch/cluster/metadata/AutoExpandReplicas.java

@@ -140,6 +140,10 @@ public boolean isEnabled() {
         return enabled;
     }
 
+    public boolean autoExpandToAll() {
+        return maxReplicas == Integer.MAX_VALUE;
+    }
+
     private OptionalInt getDesiredNumberOfReplicas(IndexMetadata indexMetadata, RoutingAllocation allocation) {
         if (enabled) {
             int numMatchingDataNodes = 0;

server/src/main/java/org/opensearch/cluster/routing/allocation/decider/AwarenessAllocationDecider.java

@@ -50,6 +50,7 @@
 import java.util.function.Function;
 
 import static java.util.Collections.emptyList;
+import static org.opensearch.cluster.metadata.IndexMetadata.INDEX_AUTO_EXPAND_REPLICAS_SETTING;
 
 /**
  * This {@link AllocationDecider} controls shard allocation based on
@@ -160,6 +161,11 @@ private Decision underCapacity(ShardRouting shardRouting, RoutingNode node, Rout
         }
 
         IndexMetadata indexMetadata = allocation.metadata().getIndexSafe(shardRouting.index());
+
+        if (INDEX_AUTO_EXPAND_REPLICAS_SETTING.get(indexMetadata.getSettings()).autoExpandToAll()) {
+            return allocation.decision(Decision.YES, NAME, "allocation awareness is ignored, this index is set to auto-expand to all");
+        }
+
         int shardCount = indexMetadata.getNumberOfReplicas() + 1; // 1 for primary
         for (String awarenessAttribute : awarenessAttributes) {
             // the node the shard exists on must be associated with an awareness attribute.

server/src/test/java/org/opensearch/cluster/routing/allocation/AwarenessAllocationTests.java

@@ -1063,4 +1063,39 @@ public void testAllocationExplainForUnassignedShardsWithUnbalancedZones() {
 
         }
     }
+
+    public void testIgnoredByAutoExpandReplicasToAll() {
+        final Settings settings = Settings.builder()
+            .put(AwarenessAllocationDecider.CLUSTER_ROUTING_ALLOCATION_AWARENESS_ATTRIBUTE_SETTING.getKey(), "zone")
+            .build();
+
+        final AllocationService strategy = createAllocationService(settings);
+
+        final IndexMetadata.Builder metadataBuilder = IndexMetadata.builder("test")
+            .settings(
+                settings(Version.CURRENT).put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+                    .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 100)
+                    .put(IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS, "0-all")
+            );
+
+        final Metadata metadata = Metadata.builder().put(metadataBuilder).build();
+
+        final DiscoveryNodes nodes = DiscoveryNodes.builder()
+            .add(newNode("A-0", singletonMap("zone", "a")))
+            .add(newNode("A-1", singletonMap("zone", "a")))
+            .add(newNode("A-2", singletonMap("zone", "a")))
+            .add(newNode("B-0", singletonMap("zone", "b")))
+            .build();
+
+        final ClusterState clusterState = applyStartedShardsUntilNoChange(
+            ClusterState.builder(ClusterName.CLUSTER_NAME_SETTING.get(Settings.EMPTY))
+                .metadata(metadata)
+                .routingTable(RoutingTable.builder().addAsNew(metadata.index("test")).build())
+                .nodes(nodes)
+                .build(),
+            strategy
+        );
+
+        assertThat(clusterState.getRoutingNodes().shardsWithState(UNASSIGNED).size(), equalTo(0));
+    }
 }