[Weighted Routing] Add support for discovered master and remove local weights in the response

CHANGELOG.md

@@ -20,6 +20,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add CI bundle pattern to distribution download ([#5348](https://github.com/opensearch-project/OpenSearch/pull/5348))
 - Add support for ppc64le architecture ([#5459](https://github.com/opensearch-project/OpenSearch/pull/5459))
 - Added @gbbafna as an OpenSearch maintainer ([#5668](https://github.com/opensearch-project/OpenSearch/pull/5668))
+- Add support for discovered master and remove local weights ([#5680](https://github.com/opensearch-project/OpenSearch/pull/5680))
 
 
 ### Dependencies

server/src/internalClusterTest/java/org/opensearch/cluster/routing/WeightedRoutingIT.java

@@ -219,7 +219,6 @@ public void testGetWeightedRouting_WeightsAreSet() throws IOException {
             .setRequestLocal(true)
             .get();
         assertEquals(weightedRouting, weightedRoutingResponse.weights());
-        assertEquals("1.0", weightedRoutingResponse.getLocalNodeWeight());
 
         // get api to fetch local node weight for a node in zone b
         weightedRoutingResponse = internalCluster().client(randomFrom(nodes_in_zone_b.get(0), nodes_in_zone_b.get(1)))
@@ -230,7 +229,6 @@ public void testGetWeightedRouting_WeightsAreSet() throws IOException {
             .setRequestLocal(true)
             .get();
         assertEquals(weightedRouting, weightedRoutingResponse.weights());
-        assertEquals("2.0", weightedRoutingResponse.getLocalNodeWeight());
 
         // get api to fetch local node weight for a node in zone c
         weightedRoutingResponse = internalCluster().client(randomFrom(nodes_in_zone_c.get(0), nodes_in_zone_c.get(1)))
@@ -241,7 +239,6 @@ public void testGetWeightedRouting_WeightsAreSet() throws IOException {
             .setRequestLocal(true)
             .get();
         assertEquals(weightedRouting, weightedRoutingResponse.weights());
-        assertEquals("3.0", weightedRoutingResponse.getLocalNodeWeight());
     }
 
     public void testWeightedRoutingMetadataOnOSProcessRestart() throws Exception {

server/src/main/java/org/opensearch/action/admin/cluster/shards/routing/weighted/get/ClusterGetWeightedRoutingResponse.java

@@ -31,26 +31,37 @@
  * @opensearch.internal
  */
 public class ClusterGetWeightedRoutingResponse extends ActionResponse implements ToXContentObject {
-    private WeightedRouting weightedRouting;
-    private String localNodeWeight;
-    private static final String NODE_WEIGHT = "node_weight";
+    public WeightedRouting getWeightedRouting() {
+        return weightedRouting;
+    }
+
+    private final WeightedRouting weightedRouting;
 
-    public String getLocalNodeWeight() {
-        return localNodeWeight;
+    public Boolean getDiscoveredMaster() {
+        return discoveredMaster;
     }
 
+    private final Boolean discoveredMaster;
+
+    private static final String DISCOVERED_MASTER = "discovered_master";
+
     ClusterGetWeightedRoutingResponse() {
         this.weightedRouting = null;
+        this.discoveredMaster = null;
     }
 
-    public ClusterGetWeightedRoutingResponse(String localNodeWeight, WeightedRouting weightedRouting) {
-        this.localNodeWeight = localNodeWeight;
+    public ClusterGetWeightedRoutingResponse(WeightedRouting weightedRouting, Boolean discoveredMaster) {
+        this.discoveredMaster = discoveredMaster;
         this.weightedRouting = weightedRouting;
     }
 
     ClusterGetWeightedRoutingResponse(StreamInput in) throws IOException {
         if (in.available() != 0) {
             this.weightedRouting = new WeightedRouting(in);
+            this.discoveredMaster = in.readOptionalBoolean();
+        } else {
+            this.weightedRouting = null;
+            this.discoveredMaster = null;
         }
     }
 
@@ -68,6 +79,9 @@ public void writeTo(StreamOutput out) throws IOException {
         if (weightedRouting != null) {
             weightedRouting.writeTo(out);
         }
+        if (discoveredMaster != null) {
+            out.writeOptionalBoolean(discoveredMaster);
+        }
     }
 
     @Override
@@ -77,8 +91,8 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
             for (Map.Entry<String, Double> entry : weightedRouting.weights().entrySet()) {
                 builder.field(entry.getKey(), entry.getValue().toString());
             }
-            if (localNodeWeight != null) {
-                builder.field(NODE_WEIGHT, localNodeWeight);
+            if (discoveredMaster != null) {
+                builder.field(DISCOVERED_MASTER, discoveredMaster);
             }
         }
         builder.endObject();
@@ -89,37 +103,37 @@ public static ClusterGetWeightedRoutingResponse fromXContent(XContentParser pars
         ensureExpectedToken(XContentParser.Token.START_OBJECT, parser.nextToken(), parser);
         XContentParser.Token token;
         String attrKey = null, attrValue = null;
-        String localNodeWeight = null;
+        Boolean discoveredMaster = null;
         Map<String, Double> weights = new HashMap<>();
 
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
             if (token == XContentParser.Token.FIELD_NAME) {
                 attrKey = parser.currentName();
             } else if (token == XContentParser.Token.VALUE_STRING) {
                 attrValue = parser.text();
-                if (attrKey != null && attrKey.equals(NODE_WEIGHT)) {
-                    localNodeWeight = attrValue;
-                } else if (attrKey != null) {
+                if (attrKey != null) {
                     weights.put(attrKey, Double.parseDouble(attrValue));
                 }
+            } else if (token == XContentParser.Token.VALUE_BOOLEAN && attrKey != null && attrKey.equals(DISCOVERED_MASTER)) {
+                discoveredMaster = Boolean.parseBoolean(parser.text());
             } else {
                 throw new OpenSearchParseException("failed to parse weighted routing response");
             }
         }
         WeightedRouting weightedRouting = new WeightedRouting("", weights);
-        return new ClusterGetWeightedRoutingResponse(localNodeWeight, weightedRouting);
+        return new ClusterGetWeightedRoutingResponse(weightedRouting, discoveredMaster);
     }
 
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         ClusterGetWeightedRoutingResponse that = (ClusterGetWeightedRoutingResponse) o;
-        return weightedRouting.equals(that.weightedRouting) && localNodeWeight.equals(that.localNodeWeight);
+        return weightedRouting.equals(that.weightedRouting) && discoveredMaster.equals(that.discoveredMaster);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(weightedRouting, localNodeWeight);
+        return Objects.hash(weightedRouting, discoveredMaster);
     }
 }

server/src/main/java/org/opensearch/action/admin/cluster/shards/routing/weighted/get/TransportGetWeightedRoutingAction.java

@@ -20,7 +20,6 @@
 import org.opensearch.cluster.metadata.IndexNameExpressionResolver;
 
 import org.opensearch.cluster.metadata.WeightedRoutingMetadata;
-import org.opensearch.cluster.node.DiscoveryNode;
 import org.opensearch.cluster.routing.WeightedRouting;
 import org.opensearch.cluster.routing.WeightedRoutingService;
 import org.opensearch.cluster.service.ClusterService;
@@ -89,19 +88,12 @@ protected void clusterManagerOperation(
             weightedRoutingService.verifyAwarenessAttribute(request.getAwarenessAttribute());
             WeightedRoutingMetadata weightedRoutingMetadata = state.metadata().custom(WeightedRoutingMetadata.TYPE);
             ClusterGetWeightedRoutingResponse clusterGetWeightedRoutingResponse = new ClusterGetWeightedRoutingResponse();
-            String weight = null;
             if (weightedRoutingMetadata != null && weightedRoutingMetadata.getWeightedRouting() != null) {
                 WeightedRouting weightedRouting = weightedRoutingMetadata.getWeightedRouting();
-                if (request.local()) {
-                    DiscoveryNode localNode = state.getNodes().getLocalNode();
-                    if (localNode.getAttributes().get(request.getAwarenessAttribute()) != null) {
-                        String attrVal = localNode.getAttributes().get(request.getAwarenessAttribute());
-                        if (weightedRouting.weights().containsKey(attrVal)) {
-                            weight = weightedRouting.weights().get(attrVal).toString();
-                        }
-                    }
-                }
-                clusterGetWeightedRoutingResponse = new ClusterGetWeightedRoutingResponse(weight, weightedRouting);
+                clusterGetWeightedRoutingResponse = new ClusterGetWeightedRoutingResponse(
+                    weightedRouting,
+                    state.nodes().getClusterManagerNodeId() != null
+                );
             }
             listener.onResponse(clusterGetWeightedRoutingResponse);
         } catch (Exception ex) {

server/src/test/java/org/opensearch/cluster/action/shard/routing/weighted/get/ClusterGetWeightedRoutingResponseTests.java

@@ -21,7 +21,7 @@ public class ClusterGetWeightedRoutingResponseTests extends AbstractXContentTest
     protected ClusterGetWeightedRoutingResponse createTestInstance() {
         Map<String, Double> weights = Map.of("zone_A", 1.0, "zone_B", 0.0, "zone_C", 1.0);
         WeightedRouting weightedRouting = new WeightedRouting("", weights);
-        ClusterGetWeightedRoutingResponse response = new ClusterGetWeightedRoutingResponse("1", weightedRouting);
+        ClusterGetWeightedRoutingResponse response = new ClusterGetWeightedRoutingResponse(weightedRouting, true);
         return response;
     }
 

server/src/test/java/org/opensearch/cluster/action/shard/routing/weighted/get/TransportGetWeightedRoutingActionTests.java

@@ -191,7 +191,6 @@ public void testGetWeightedRouting_WeightsNotSetInMetadata() {
         ClusterState state = clusterService.state();
 
         ClusterGetWeightedRoutingResponse response = ActionTestUtils.executeBlocking(transportGetWeightedRoutingAction, request.request());
-        assertEquals(response.getLocalNodeWeight(), null);
         assertEquals(response.weights(), null);
     }
 
@@ -231,7 +230,8 @@ public void testGetWeightedRoutingLocalWeight_WeightsSetInMetadata() {
         ClusterServiceUtils.setState(clusterService, builder);
 
         ClusterGetWeightedRoutingResponse response = ActionTestUtils.executeBlocking(transportGetWeightedRoutingAction, request.request());
-        assertEquals("0.0", response.getLocalNodeWeight());
+        assertEquals(true, response.getDiscoveredMaster());
+        assertEquals(weights, response.getWeightedRouting().weights());
     }
 
     public void testGetWeightedRoutingLocalWeight_WeightsNotSetInMetadata() {
@@ -250,7 +250,7 @@ public void testGetWeightedRoutingLocalWeight_WeightsNotSetInMetadata() {
         ClusterServiceUtils.setState(clusterService, builder);
 
         ClusterGetWeightedRoutingResponse response = ActionTestUtils.executeBlocking(transportGetWeightedRoutingAction, request.request());
-        assertEquals(null, response.getLocalNodeWeight());
+        assertEquals(null, response.getWeightedRouting());
     }
 
     @After