Add GET api to get shard routing weights

CHANGELOG.md

@@ -62,6 +62,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - [CCR] Add getHistoryOperationsFromTranslog method to fetch the history snapshot from translogs ([#3948](https://github.com/opensearch-project/OpenSearch/pull/3948))
 - [Remote Store] Change behaviour in replica recovery for remote translog enabled indices ([#4318](https://github.com/opensearch-project/OpenSearch/pull/4318))
 - PUT api for weighted shard routing ([#4272](https://github.com/opensearch-project/OpenSearch/pull/4272))
+- GET api for weighted shard routing([#4275](https://github.com/opensearch-project/OpenSearch/pull/4275/))
 - Unmute test RelocationIT.testRelocationWhileIndexingRandom ([#4580](https://github.com/opensearch-project/OpenSearch/pull/4580))
 - Add DecommissionService and helper to execute awareness attribute decommissioning ([#4084](https://github.com/opensearch-project/OpenSearch/pull/4084))
 - Further simplification of the ZIP publication implementation ([#4360](https://github.com/opensearch-project/OpenSearch/pull/4360))

client/rest-high-level/src/test/java/org/opensearch/client/RestHighLevelClientTests.java

@@ -890,6 +890,7 @@ public void testApiNamingConventions() throws Exception {
             "search_shards",
             "remote_store.restore",
             "cluster.put_weighted_routing",
+            "cluster.get_weighted_routing",
             "cluster.put_decommission_awareness",
             "cluster.get_decommission_awareness", };
         List<String> booleanReturnMethods = Arrays.asList("security.enable_user", "security.disable_user", "security.change_password");

rest-api-spec/src/main/resources/rest-api-spec/api/cluster.get_weighted_routing.json

@@ -0,0 +1,25 @@
+{
+  "cluster.get_weighted_routing": {
+    "documentation": {
+      "url": "https://opensearch.org/docs/latest/opensearch/rest-api/weighted-routing/get",
+      "description": "Fetches weighted shard routing weights"
+    },
+    "stability": "stable",
+    "url": {
+      "paths": [
+        {
+          "path": "/_cluster/routing/awareness/{attribute}/weights",
+          "methods": [
+            "GET"
+          ],
+          "parts": {
+            "attribute": {
+              "type": "string",
+              "description": "Awareness attribute name"
+            }
+          }
+        }
+      ]
+    }
+  }
+}

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

@@ -0,0 +1,245 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.cluster.routing;
+
+import org.opensearch.action.admin.cluster.health.ClusterHealthResponse;
+import org.opensearch.action.admin.cluster.shards.routing.weighted.get.ClusterGetWeightedRoutingResponse;
+import org.opensearch.action.admin.cluster.shards.routing.weighted.put.ClusterPutWeightedRoutingResponse;
+import org.opensearch.common.settings.Settings;
+import org.opensearch.test.OpenSearchIntegTestCase;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.Matchers.equalTo;
+
+@OpenSearchIntegTestCase.ClusterScope(scope = OpenSearchIntegTestCase.Scope.TEST, numDataNodes = 0, minNumDataNodes = 3)
+public class WeightedRoutingIT extends OpenSearchIntegTestCase {
+
+    public void testPutWeightedRouting() {
+        Settings commonSettings = Settings.builder()
+            .put("cluster.routing.allocation.awareness.attributes", "zone")
+            .put("cluster.routing.allocation.awareness.force.zone.values", "a,b,c")
+            .build();
+
+        logger.info("--> starting 6 nodes on different zones");
+        int nodeCountPerAZ = 2;
+
+        logger.info("--> starting a dedicated cluster manager node");
+        internalCluster().startClusterManagerOnlyNode(Settings.builder().put(commonSettings).build());
+
+        logger.info("--> starting 1 nodes on zones 'a' & 'b' & 'c'");
+        List<String> nodes_in_zone_a = internalCluster().startDataOnlyNodes(
+            nodeCountPerAZ,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build()
+        );
+        List<String> nodes_in_zone_b = internalCluster().startDataOnlyNodes(
+            nodeCountPerAZ,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "b").build()
+        );
+        List<String> nodes_in_zone_c = internalCluster().startDataOnlyNodes(
+            nodeCountPerAZ,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "c").build()
+        );
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("7").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ensureGreen();
+
+        logger.info("--> setting shard routing weights for weighted round robin");
+        Map<String, Double> weights = Map.of("a", 1.0, "b", 2.0, "c", 3.0);
+        WeightedRouting weightedRouting = new WeightedRouting("zone", weights);
+
+        ClusterPutWeightedRoutingResponse response = client().admin()
+            .cluster()
+            .prepareWeightedRouting()
+            .setWeightedRouting(weightedRouting)
+            .get();
+        assertEquals(response.isAcknowledged(), true);
+
+        // put call made on a data node in zone a
+        response = internalCluster().client(randomFrom(nodes_in_zone_a.get(0), nodes_in_zone_a.get(1)))
+            .admin()
+            .cluster()
+            .prepareWeightedRouting()
+            .setWeightedRouting(weightedRouting)
+            .get();
+        assertEquals(response.isAcknowledged(), true);
+    }
+
+    public void testPutWeightedRouting_InvalidAwarenessAttribute() {
+        Settings commonSettings = Settings.builder()
+            .put("cluster.routing.allocation.awareness.attributes", "zone")
+            .put("cluster.routing.allocation.awareness.force.zone.values", "a,b,c")
+            .build();
+
+        internalCluster().startNodes(
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "b").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "c").build()
+        );
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("3").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ensureGreen();
+
+        logger.info("--> setting shard routing weights for weighted round robin");
+        Map<String, Double> weights = Map.of("a", 1.0, "b", 2.0, "c", 3.0);
+        WeightedRouting weightedRouting = new WeightedRouting("zone1", weights);
+
+        assertThrows(
+            IllegalArgumentException.class,
+            () -> client().admin().cluster().prepareWeightedRouting().setWeightedRouting(weightedRouting).get()
+        );
+    }
+
+    public void testPutWeightedRouting_MoreThanOneZoneHasZeroWeight() {
+        Settings commonSettings = Settings.builder()
+            .put("cluster.routing.allocation.awareness.attributes", "zone")
+            .put("cluster.routing.allocation.awareness.force.zone.values", "a,b,c")
+            .build();
+
+        internalCluster().startNodes(
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "b").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "c").build()
+        );
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("3").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ensureGreen();
+
+        logger.info("--> setting shard routing weights for weighted round robin");
+        Map<String, Double> weights = Map.of("a", 1.0, "b", 0.0, "c", 0.0);
+        WeightedRouting weightedRouting = new WeightedRouting("zone1", weights);
+
+        assertThrows(
+            IllegalArgumentException.class,
+            () -> client().admin().cluster().prepareWeightedRouting().setWeightedRouting(weightedRouting).get()
+        );
+    }
+
+    public void testGetWeightedRouting_WeightsNotSet() {
+        Settings commonSettings = Settings.builder()
+            .put("cluster.routing.allocation.awareness.attributes", "zone")
+            .put("cluster.routing.allocation.awareness.force.zone.values", "a,b,c")
+            .build();
+
+        internalCluster().startNodes(
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "b").build(),
+            Settings.builder().put(commonSettings).put("node.attr.zone", "c").build()
+        );
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("3").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ensureGreen();
+
+        ClusterGetWeightedRoutingResponse weightedRoutingResponse = client().admin()
+            .cluster()
+            .prepareGetWeightedRouting()
+            .setAwarenessAttribute("zone")
+            .get();
+        assertNull(weightedRoutingResponse.weights());
+    }
+
+    public void testGetWeightedRouting_WeightsAreSet() throws IOException {
+
+        Settings commonSettings = Settings.builder()
+            .put("cluster.routing.allocation.awareness.attributes", "zone")
+            .put("cluster.routing.allocation.awareness.force.zone.values", "a,b,c")
+            .build();
+
+        int nodeCountPerAZ = 2;
+
+        logger.info("--> starting a dedicated cluster manager node");
+        internalCluster().startClusterManagerOnlyNode(Settings.builder().put(commonSettings).build());
+
+        logger.info("--> starting 2 nodes on zones 'a' & 'b' & 'c'");
+        List<String> nodes_in_zone_a = internalCluster().startDataOnlyNodes(
+            nodeCountPerAZ,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build()
+        );
+        List<String> nodes_in_zone_b = internalCluster().startDataOnlyNodes(
+            nodeCountPerAZ,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "b").build()
+        );
+        List<String> nodes_in_zone_c = internalCluster().startDataOnlyNodes(
+            nodeCountPerAZ,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "c").build()
+        );
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("7").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ensureGreen();
+
+        logger.info("--> setting shard routing weights for weighted round robin");
+        Map<String, Double> weights = Map.of("a", 1.0, "b", 2.0, "c", 3.0);
+        WeightedRouting weightedRouting = new WeightedRouting("zone", weights);
+        // put api call to set weights
+        ClusterPutWeightedRoutingResponse response = client().admin()
+            .cluster()
+            .prepareWeightedRouting()
+            .setWeightedRouting(weightedRouting)
+            .get();
+        assertEquals(response.isAcknowledged(), true);
+
+        // get api call to fetch weights
+        ClusterGetWeightedRoutingResponse weightedRoutingResponse = client().admin()
+            .cluster()
+            .prepareGetWeightedRouting()
+            .setAwarenessAttribute("zone")
+            .get();
+        assertEquals(weightedRouting, weightedRoutingResponse.weights());
+
+        // get api to fetch local node weight for a node in zone a
+        weightedRoutingResponse = internalCluster().client(randomFrom(nodes_in_zone_a.get(0), nodes_in_zone_a.get(1)))
+            .admin()
+            .cluster()
+            .prepareGetWeightedRouting()
+            .setAwarenessAttribute("zone")
+            .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)))
+            .admin()
+            .cluster()
+            .prepareGetWeightedRouting()
+            .setAwarenessAttribute("zone")
+            .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)))
+            .admin()
+            .cluster()
+            .prepareGetWeightedRouting()
+            .setAwarenessAttribute("zone")
+            .setRequestLocal(true)
+            .get();
+        assertEquals(weightedRouting, weightedRoutingResponse.weights());
+        assertEquals("3.0", weightedRoutingResponse.getLocalNodeWeight());
+    }
+}

server/src/main/java/org/opensearch/action/ActionModule.java

@@ -83,6 +83,8 @@
 import org.opensearch.action.admin.cluster.settings.TransportClusterUpdateSettingsAction;
 import org.opensearch.action.admin.cluster.shards.ClusterSearchShardsAction;
 import org.opensearch.action.admin.cluster.shards.TransportClusterSearchShardsAction;
+import org.opensearch.action.admin.cluster.shards.routing.weighted.get.ClusterGetWeightedRoutingAction;
+import org.opensearch.action.admin.cluster.shards.routing.weighted.get.TransportGetWeightedRoutingAction;
 import org.opensearch.action.admin.cluster.shards.routing.weighted.put.ClusterAddWeightedRoutingAction;
 import org.opensearch.action.admin.cluster.shards.routing.weighted.put.TransportAddWeightedRoutingAction;
 import org.opensearch.action.admin.cluster.snapshots.clone.CloneSnapshotAction;
@@ -299,6 +301,7 @@
 import org.opensearch.rest.action.admin.cluster.RestCloneSnapshotAction;
 import org.opensearch.rest.action.admin.cluster.RestClusterAllocationExplainAction;
 import org.opensearch.rest.action.admin.cluster.RestClusterGetSettingsAction;
+import org.opensearch.rest.action.admin.cluster.RestClusterGetWeightedRoutingAction;
 import org.opensearch.rest.action.admin.cluster.RestClusterHealthAction;
 import org.opensearch.rest.action.admin.cluster.RestClusterPutWeightedRoutingAction;
 import org.opensearch.rest.action.admin.cluster.RestClusterRerouteAction;
@@ -573,6 +576,7 @@ public <Request extends ActionRequest, Response extends ActionResponse> void reg
         actions.register(SnapshotsStatusAction.INSTANCE, TransportSnapshotsStatusAction.class);
 
         actions.register(ClusterAddWeightedRoutingAction.INSTANCE, TransportAddWeightedRoutingAction.class);
+        actions.register(ClusterGetWeightedRoutingAction.INSTANCE, TransportGetWeightedRoutingAction.class);
         actions.register(IndicesStatsAction.INSTANCE, TransportIndicesStatsAction.class);
         actions.register(IndicesSegmentsAction.INSTANCE, TransportIndicesSegmentsAction.class);
         actions.register(IndicesShardStoresAction.INSTANCE, TransportIndicesShardStoresAction.class);
@@ -759,6 +763,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
         registerHandler.accept(new RestOpenIndexAction());
         registerHandler.accept(new RestAddIndexBlockAction());
         registerHandler.accept(new RestClusterPutWeightedRoutingAction());
+        registerHandler.accept(new RestClusterGetWeightedRoutingAction());
 
         registerHandler.accept(new RestUpdateSettingsAction());
         registerHandler.accept(new RestGetSettingsAction());

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

@@ -0,0 +1,25 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.action.admin.cluster.shards.routing.weighted.get;
+
+import org.opensearch.action.ActionType;
+
+/**
+ * Action to get weights for weighted round-robin search routing policy.
+ *
+ * @opensearch.internal
+ */
+public class ClusterGetWeightedRoutingAction extends ActionType<ClusterGetWeightedRoutingResponse> {
+    public static final ClusterGetWeightedRoutingAction INSTANCE = new ClusterGetWeightedRoutingAction();
+    public static final String NAME = "cluster:admin/routing/awareness/weights/get";
+
+    private ClusterGetWeightedRoutingAction() {
+        super(NAME, ClusterGetWeightedRoutingResponse::new);
+    }
+}