xds: XdsClient support for hashing based load balancing (#7859)

This change adds two parts to XdsClient for receiving configurations that support hashing based load balancing policies:

- Each Route contains a list of HashPolicys, which specifies the hash value generation for requests routed to that Route.
- Each Cluster resource can specify lb policy other than "round_robin". If it is "ring_hash", it contains the configuration for mapping each RPC's hash value to one of the endpoints.

xds/src/main/java/io/grpc/xds/CdsLoadBalancer2.java

@@ -34,11 +34,7 @@ import io.grpc.xds.ClusterResolverLoadBalancerProvider.ClusterResolverConfig;
 import io.grpc.xds.ClusterResolverLoadBalancerProvider.ClusterResolverConfig.DiscoveryMechanism;
 import io.grpc.xds.XdsClient.CdsResourceWatcher;
 import io.grpc.xds.XdsClient.CdsUpdate;
-import io.grpc.xds.XdsClient.CdsUpdate.AggregateClusterConfig;
-import io.grpc.xds.XdsClient.CdsUpdate.ClusterConfig;
 import io.grpc.xds.XdsClient.CdsUpdate.ClusterType;
-import io.grpc.xds.XdsClient.CdsUpdate.EdsClusterConfig;
-import io.grpc.xds.XdsClient.CdsUpdate.LogicalDnsClusterConfig;
 import io.grpc.xds.XdsLogger.XdsLogLevel;
 import io.grpc.xds.XdsSubchannelPickers.ErrorPicker;
 import java.util.ArrayDeque;
@@ -153,17 +149,16 @@ final class CdsLoadBalancer2 extends LoadBalancer {
           }
           if (clusterState.isLeaf) {
             DiscoveryMechanism instance;
-            if (clusterState.result instanceof EdsClusterConfig) {
+            if (clusterState.result.clusterType() ==  ClusterType.EDS) {
-              EdsClusterConfig clusterConfig = (EdsClusterConfig) clusterState.result;
+              instance = DiscoveryMechanism.forEds(
-              instance = DiscoveryMechanism.forEds(clusterState.name, clusterConfig.edsServiceName,
+                  clusterState.name, clusterState.result.edsServiceName(),
-                  clusterConfig.lrsServerName, clusterConfig.maxConcurrentRequests,
+                  clusterState.result.lrsServerName(), clusterState.result.maxConcurrentRequests(),
-                  clusterConfig.upstreamTlsContext);
+                  clusterState.result.upstreamTlsContext());
             } else {  // logical DNS
-              LogicalDnsClusterConfig clusterConfig =
+              instance = DiscoveryMechanism.forLogicalDns(
-                  (LogicalDnsClusterConfig) clusterState.result;
+                  clusterState.name, clusterState.result.lrsServerName(),
-              instance = DiscoveryMechanism.forLogicalDns(clusterState.name,
+                  clusterState.result.maxConcurrentRequests(),
-                  clusterConfig.lrsServerName, clusterConfig.maxConcurrentRequests,
+                  clusterState.result.upstreamTlsContext());
-                  clusterConfig.upstreamTlsContext);
             }
             instances.add(instance);
           } else {
@@ -183,7 +178,7 @@ final class CdsLoadBalancer2 extends LoadBalancer {
         helper.updateBalancingState(TRANSIENT_FAILURE, new ErrorPicker(unavailable));
         return;
       }
-      String endpointPickingPolicy = root.result.lbPolicy;
+      String endpointPickingPolicy = root.result.lbPolicy();
       LoadBalancerProvider localityPickingLbProvider =
           lbRegistry.getProvider(XdsLbPolicies.WEIGHTED_TARGET_POLICY_NAME);  // hardcoded
       LoadBalancerProvider endpointPickingLbProvider =
@@ -212,7 +207,7 @@ final class CdsLoadBalancer2 extends LoadBalancer {
       @Nullable
       private Map<String, ClusterState> childClusterStates;
       @Nullable
-      private ClusterConfig result;
+      private CdsUpdate result;
       // Following fields are effectively final.
       private boolean isLeaf;
       private boolean discovered;
@@ -281,15 +276,15 @@ final class CdsLoadBalancer2 extends LoadBalancer {
             if (shutdown) {
               return;
             }
+            logger.log(XdsLogLevel.DEBUG, "Received cluster update {0}", update);
             discovered = true;
-            result = update.clusterConfig;
+            result = update;
-            if (update.clusterType == ClusterType.AGGREGATE) {
+            if (update.clusterType() == ClusterType.AGGREGATE) {
               isLeaf = false;
-              AggregateClusterConfig clusterConfig = (AggregateClusterConfig) update.clusterConfig;
+              logger.log(XdsLogLevel.INFO, "Aggregate cluster {0}, underlying clusters: {1}",
-              logger.log(XdsLogLevel.INFO, "Aggregate cluster {0}", update.clusterName);
+                  update.clusterName(), update.prioritizedClusterNames());
-              logger.log(XdsLogLevel.DEBUG, "Cluster config: {0}", clusterConfig);
               Map<String, ClusterState> newChildStates = new LinkedHashMap<>();
-              for (String cluster : clusterConfig.prioritizedClusterNames) {
+              for (String cluster : update.prioritizedClusterNames()) {
                 if (childClusterStates == null || !childClusterStates.containsKey(cluster)) {
                   ClusterState childState = new ClusterState(cluster);
                   childState.start();
@@ -304,18 +299,13 @@ final class CdsLoadBalancer2 extends LoadBalancer {
                 }
               }
               childClusterStates = newChildStates;
-            } else if (update.clusterType == ClusterType.EDS) {
+            } else if (update.clusterType() == ClusterType.EDS) {
               isLeaf = true;
-              EdsClusterConfig clusterConfig = (EdsClusterConfig) update.clusterConfig;
               logger.log(XdsLogLevel.INFO, "EDS cluster {0}, edsServiceName: {1}",
-                  update.clusterName, clusterConfig.edsServiceName);
+                  update.clusterName(), update.edsServiceName());
-              logger.log(XdsLogLevel.DEBUG, "Cluster config: {0}", clusterConfig);
             } else {  // logical DNS
               isLeaf = true;
-              LogicalDnsClusterConfig clusterConfig =
+              logger.log(XdsLogLevel.INFO, "Logical DNS cluster {0}", update.clusterName());
-                  (LogicalDnsClusterConfig) update.clusterConfig;
-              logger.log(XdsLogLevel.INFO, "Logical DNS cluster {0}", update.clusterName);
-              logger.log(XdsLogLevel.DEBUG, "Cluster config: {0}", clusterConfig);
             }
             handleClusterDiscovered();
           }

xds/src/main/java/io/grpc/xds/ClientXdsClient.java

@@ -21,6 +21,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import static io.grpc.xds.EnvoyProtoData.TRANSPORT_SOCKET_NAME_TLS;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.CaseFormat;
 import com.google.common.base.Stopwatch;
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableList;
@@ -34,6 +35,7 @@ import io.envoyproxy.envoy.config.cluster.v3.Cluster;
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.CustomClusterType;
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.DiscoveryType;
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.LbPolicy;
+import io.envoyproxy.envoy.config.cluster.v3.Cluster.RingHashLbConfig;
 import io.envoyproxy.envoy.config.core.v3.HttpProtocolOptions;
 import io.envoyproxy.envoy.config.core.v3.RoutingPriority;
 import io.envoyproxy.envoy.config.endpoint.v3.ClusterLoadAssignment;
@@ -65,11 +67,9 @@ import io.grpc.xds.Matchers.PathMatcher;
 import io.grpc.xds.VirtualHost.Route;
 import io.grpc.xds.VirtualHost.Route.RouteAction;
 import io.grpc.xds.VirtualHost.Route.RouteAction.ClusterWeight;
+import io.grpc.xds.VirtualHost.Route.RouteAction.HashPolicy;
 import io.grpc.xds.VirtualHost.Route.RouteMatch;
-import io.grpc.xds.XdsClient.CdsUpdate.AggregateClusterConfig;
+import io.grpc.xds.XdsClient.CdsUpdate.HashFunction;
-import io.grpc.xds.XdsClient.CdsUpdate.ClusterType;
-import io.grpc.xds.XdsClient.CdsUpdate.EdsClusterConfig;
-import io.grpc.xds.XdsClient.CdsUpdate.LogicalDnsClusterConfig;
 import io.grpc.xds.XdsLogger.XdsLogLevel;
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
@@ -96,6 +96,8 @@ final class ClientXdsClient extends AbstractXdsClient {
   @VisibleForTesting
   static final String AGGREGATE_CLUSTER_TYPE_NAME = "envoy.clusters.aggregate";
   private static final String HTTP_FAULT_FILTER_NAME = "envoy.fault";
+  @VisibleForTesting
+  static final String HASH_POLICY_FILTER_STATE_KEY = "io.grpc.channel_id";
   private static final String TYPE_URL_HTTP_CONNECTION_MANAGER_V2 =
       "type.googleapis.com/envoy.config.filter.network.http_connection_manager.v2"
           + ".HttpConnectionManager";
@@ -468,10 +470,42 @@ final class ClientXdsClient extends AbstractXdsClient {
         timeoutNano = Durations.toNanos(maxStreamDuration.getMaxStreamDuration());
       }
     }
-    List<ClusterWeight> weightedClusters;
+    List<HashPolicy> hashPolicies = new ArrayList<>();
+    for (io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy config
+        : proto.getHashPolicyList()) {
+      HashPolicy policy = null;
+      boolean terminal = config.getTerminal();
+      switch (config.getPolicySpecifierCase()) {
+        case HEADER:
+          io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.Header headerCfg =
+              config.getHeader();
+          Pattern regEx = null;
+          String regExSubstitute = null;
+          if (headerCfg.hasRegexRewrite() && headerCfg.getRegexRewrite().hasPattern()
+              && headerCfg.getRegexRewrite().getPattern().hasGoogleRe2()) {
+            regEx = Pattern.compile(headerCfg.getRegexRewrite().getPattern().getRegex());
+            regExSubstitute = headerCfg.getRegexRewrite().getSubstitution();
+          }
+          policy = HashPolicy.forHeader(
+              terminal, headerCfg.getHeaderName(), regEx, regExSubstitute);
+          break;
+        case FILTER_STATE:
+          if (config.getFilterState().getKey().equals(HASH_POLICY_FILTER_STATE_KEY)) {
+            policy = HashPolicy.forChannelId(terminal);
+          }
+          break;
+        default:
+          // Ignore
+      }
+      if (policy != null) {
+        hashPolicies.add(policy);
+      }
+    }
+
     switch (proto.getClusterSpecifierCase()) {
       case CLUSTER:
-        return StructOrError.fromStruct(RouteAction.forCluster(proto.getCluster(), timeoutNano));
+        return StructOrError.fromStruct(RouteAction.forCluster(
+            proto.getCluster(), hashPolicies, timeoutNano));
       case CLUSTER_HEADER:
         return null;
       case WEIGHTED_CLUSTERS:
@@ -480,7 +514,7 @@ final class ClientXdsClient extends AbstractXdsClient {
         if (clusterWeights.isEmpty()) {
           return StructOrError.fromError("No cluster found in weighted cluster list");
         }
-        weightedClusters = new ArrayList<>();
+        List<ClusterWeight> weightedClusters = new ArrayList<>();
         for (io.envoyproxy.envoy.config.route.v3.WeightedCluster.ClusterWeight clusterWeight
             : clusterWeights) {
           StructOrError<ClusterWeight> clusterWeightOrError = parseClusterWeight(clusterWeight);
@@ -492,7 +526,7 @@ final class ClientXdsClient extends AbstractXdsClient {
         }
         // TODO(chengyuanzhang): validate if the sum of weights equals to total weight.
         return StructOrError.fromStruct(RouteAction.forWeightedClusters(
-            weightedClusters, timeoutNano));
+            weightedClusters, hashPolicies, timeoutNano));
       case CLUSTERSPECIFIER_NOT_SET:
       default:
         return StructOrError.fromError(
@@ -713,30 +747,44 @@ final class ClientXdsClient extends AbstractXdsClient {
       if (!cdsResourceSubscribers.containsKey(clusterName)) {
         continue;
       }
-      // The lb_policy field must be set to ROUND_ROBIN.
+      StructOrError<CdsUpdate.Builder> structOrError;
-      if (!cluster.getLbPolicy().equals(LbPolicy.ROUND_ROBIN)) {
-        nackResponse(ResourceType.CDS, nonce,
-            "Cluster " + clusterName + ": unsupported Lb policy: " + cluster.getLbPolicy());
-        return;
-      }
-      String lbPolicy = "round_robin";
-      CdsUpdate update = null;
       switch (cluster.getClusterDiscoveryTypeCase()) {
         case TYPE:
-          update = parseNonAggregateCluster(cluster, nonce, lbPolicy, edsResources);
+          structOrError = parseNonAggregateCluster(cluster, edsResources);
           break;
         case CLUSTER_TYPE:
-          update = parseAggregateCluster(cluster, nonce, lbPolicy);
+          structOrError = parseAggregateCluster(cluster);
           break;
         case CLUSTERDISCOVERYTYPE_NOT_SET:
         default:
           nackResponse(ResourceType.CDS, nonce,
               "Cluster " + clusterName + ": cluster discovery type unspecified");
+          return;
       }
-      if (update == null) {
+      if (structOrError.getErrorDetail() != null) {
+        nackResponse(ResourceType.CDS, nonce, structOrError.errorDetail);
         return;
       }
-      cdsUpdates.put(clusterName, update);
+      CdsUpdate.Builder updateBuilder = structOrError.getStruct();
+      String lbPolicy = CaseFormat.UPPER_UNDERSCORE.to(
+          CaseFormat.LOWER_UNDERSCORE, cluster.getLbPolicy().name());
+      if (cluster.getLbPolicy() == LbPolicy.RING_HASH) {
+        HashFunction hashFunction;
+        RingHashLbConfig lbConfig = cluster.getRingHashLbConfig();
+        if (lbConfig.getHashFunction() == RingHashLbConfig.HashFunction.XX_HASH) {
+          hashFunction = HashFunction.XX_HASH;
+        } else {
+          nackResponse(ResourceType.CDS, nonce,
+              "Cluster " + clusterName + ": unsupported ring hash function: "
+                  + lbConfig.getHashFunction());
+          return;
+        }
+        updateBuilder.lbPolicy(lbPolicy, lbConfig.getMinimumRingSize().getValue(),
+            lbConfig.getMaximumRingSize().getValue(), hashFunction);
+      } else {
+        updateBuilder.lbPolicy(lbPolicy);
+      }
+      cdsUpdates.put(clusterName, updateBuilder.build());
     }
     ackResponse(ResourceType.CDS, versionInfo, nonce);
 
@@ -756,18 +804,13 @@ final class ClientXdsClient extends AbstractXdsClient {
     }
   }
 
-  /**
+  private static StructOrError<CdsUpdate.Builder> parseAggregateCluster(Cluster cluster) {
-   * Parses CDS resource for an aggregate cluster into {@link io.grpc.xds.XdsClient.CdsUpdate}.
-   * Returns {@code null} and nack the response with the given nonce if the resource is invalid.
-   */
-  private CdsUpdate parseAggregateCluster(Cluster cluster, String nonce, String lbPolicy) {
     String clusterName = cluster.getName();
     CustomClusterType customType = cluster.getClusterType();
     String typeName = customType.getName();
     if (!typeName.equals(AGGREGATE_CLUSTER_TYPE_NAME)) {
-      nackResponse(ResourceType.CDS, nonce,
+      return StructOrError.fromError(
           "Cluster " + clusterName + ": unsupported custom cluster type: " + typeName);
-      return null;
     }
     io.envoyproxy.envoy.extensions.clusters.aggregate.v3.ClusterConfig clusterConfig;
     Any unpackedClusterConfig = customType.getTypedConfig();
@@ -779,31 +822,23 @@ final class ClientXdsClient extends AbstractXdsClient {
       clusterConfig = unpackedClusterConfig.unpack(
           io.envoyproxy.envoy.extensions.clusters.aggregate.v3.ClusterConfig.class);
     } catch (InvalidProtocolBufferException e) {
-      nackResponse(ResourceType.CDS, nonce,
+      StructOrError.fromError("Cluster " + clusterName + ": malformed ClusterConfig: " + e);
-          "Cluster " + clusterName + ": invalid cluster config: " + e);
       return null;
     }
-    AggregateClusterConfig config =
+    return StructOrError.fromStruct(CdsUpdate.forAggregate(
-        new AggregateClusterConfig(lbPolicy, clusterConfig.getClustersList());
+        clusterName, clusterConfig.getClustersList()));
-    return new CdsUpdate(clusterName, ClusterType.AGGREGATE, config);
   }
 
-  /**
+  private static StructOrError<CdsUpdate.Builder> parseNonAggregateCluster(
-   * Parses CDS resource for a non-aggregate cluster (EDS or Logical DNS) into {@link
+      Cluster cluster, Set<String> edsResources) {
-   * io.grpc.xds.XdsClient.CdsUpdate}. Returns {@code null} and nack the response with the given
-   * nonce if the resource is invalid.
-   */
-  private CdsUpdate parseNonAggregateCluster(Cluster cluster, String nonce, String lbPolicy,
-      Set<String> edsResources) {
     String clusterName = cluster.getName();
     String lrsServerName = null;
     Long maxConcurrentRequests = null;
     UpstreamTlsContext upstreamTlsContext = null;
     if (cluster.hasLrsServer()) {
       if (!cluster.getLrsServer().hasSelf()) {
-        nackResponse(ResourceType.CDS, nonce,
+        return StructOrError.fromError(
             "Cluster " + clusterName + ": only support LRS for the same management server");
-        return null;
       }
       lrsServerName = "";
     }
@@ -829,9 +864,8 @@ final class ClientXdsClient extends AbstractXdsClient {
         unpacked = any.unpack(
             io.envoyproxy.envoy.extensions.transport_sockets.tls.v3.UpstreamTlsContext.class);
       } catch (InvalidProtocolBufferException e) {
-        nackResponse(ResourceType.CDS, nonce,
+        return StructOrError.fromError(
-            "Cluster " + clusterName + ": invalid upstream TLS context: " + e);
+            "Cluster " + clusterName + ": malformed UpstreamTlsContext: " + e);
-        return null;
       }
       upstreamTlsContext = UpstreamTlsContext.fromEnvoyProtoUpstreamTlsContext(unpacked);
     }
@@ -842,9 +876,8 @@ final class ClientXdsClient extends AbstractXdsClient {
       io.envoyproxy.envoy.config.cluster.v3.Cluster.EdsClusterConfig edsClusterConfig =
           cluster.getEdsClusterConfig();
       if (!edsClusterConfig.getEdsConfig().hasAds()) {
-        nackResponse(ResourceType.CDS, nonce, "Cluster " + clusterName + ": "
+        return StructOrError.fromError("Cluster " + clusterName
-            + "field eds_cluster_config must be set to indicate to use EDS over ADS.");
+            + ": field eds_cluster_config must be set to indicate to use EDS over ADS.");
-        return null;
       }
       // If the service_name field is set, that value will be used for the EDS request.
       if (!edsClusterConfig.getServiceName().isEmpty()) {
@@ -853,17 +886,14 @@ final class ClientXdsClient extends AbstractXdsClient {
       } else {
         edsResources.add(clusterName);
       }
-      EdsClusterConfig config = new EdsClusterConfig(lbPolicy, edsServiceName,
+      return StructOrError.fromStruct(CdsUpdate.forEds(
-          lrsServerName, maxConcurrentRequests, upstreamTlsContext);
+          clusterName, edsServiceName, lrsServerName, maxConcurrentRequests, upstreamTlsContext));
-      return new CdsUpdate(clusterName, ClusterType.EDS, config);
     } else if (type.equals(DiscoveryType.LOGICAL_DNS)) {
-      LogicalDnsClusterConfig config = new LogicalDnsClusterConfig(lbPolicy, lrsServerName,
+      return StructOrError.fromStruct(CdsUpdate.forLogicalDns(
-          maxConcurrentRequests, upstreamTlsContext);
+          clusterName, lrsServerName, maxConcurrentRequests, upstreamTlsContext));
-      return new CdsUpdate(clusterName, ClusterType.LOGICAL_DNS, config);
     }
-    nackResponse(ResourceType.CDS, nonce,
+    return StructOrError.fromError(
         "Cluster " + clusterName + ": unsupported built-in discovery type: " + type);
-    return null;
   }
 
   @Override

xds/src/main/java/io/grpc/xds/VirtualHost.java

@@ -22,6 +22,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
+import com.google.re2j.Pattern;
 import io.grpc.xds.Matchers.FractionMatcher;
 import io.grpc.xds.Matchers.HeaderMatcher;
 import io.grpc.xds.Matchers.PathMatcher;
@@ -89,6 +90,9 @@ abstract class VirtualHost {
 
     @AutoValue
     abstract static class RouteAction {
+      // List of hash policies to use for ring hash load balancing.
+      abstract ImmutableList<HashPolicy> hashPolicies();
+
       @Nullable
       abstract Long timeoutNano();
 
@@ -98,21 +102,23 @@ abstract class VirtualHost {
       @Nullable
       abstract ImmutableList<ClusterWeight> weightedClusters();
 
-      static RouteAction forCluster(String cluster, @Nullable Long timeoutNano) {
+      static RouteAction forCluster(String cluster, List<HashPolicy> hashPolicies,
+          @Nullable Long timeoutNano) {
         checkNotNull(cluster, "cluster");
-        return RouteAction.create(timeoutNano, cluster, null);
+        return RouteAction.create(hashPolicies, timeoutNano, cluster, null);
       }
 
       static RouteAction forWeightedClusters(List<ClusterWeight> weightedClusters,
-          @Nullable Long timeoutNano) {
+          List<HashPolicy> hashPolicies, @Nullable Long timeoutNano) {
         checkNotNull(weightedClusters, "weightedClusters");
         checkArgument(!weightedClusters.isEmpty(), "empty cluster list");
-        return RouteAction.create(timeoutNano, null, weightedClusters);
+        return RouteAction.create(hashPolicies, timeoutNano, null, weightedClusters);
       }
 
-      private static RouteAction create(@Nullable Long timeoutNano, @Nullable String cluster,
+      private static RouteAction create(List<HashPolicy> hashPolicies, @Nullable Long timeoutNano,
-          @Nullable List<ClusterWeight> weightedClusters) {
+          @Nullable String cluster, @Nullable List<ClusterWeight> weightedClusters) {
-        return new AutoValue_VirtualHost_Route_RouteAction(timeoutNano, cluster,
+        return new AutoValue_VirtualHost_Route_RouteAction(
+            ImmutableList.copyOf(hashPolicies), timeoutNano, cluster,
             weightedClusters == null ? null : ImmutableList.copyOf(weightedClusters));
       }
 
@@ -130,6 +136,52 @@ abstract class VirtualHost {
               httpFault);
         }
       }
+
+      // Configuration for the route's hashing policy if the upstream cluster uses a hashing load
+      // balancer.
+      @AutoValue
+      abstract static class HashPolicy {
+        // The specifier that indicates the component of the request to be hashed on.
+        abstract Type type();
+
+        // The flag that short-circuits the hash computing.
+        abstract boolean isTerminal();
+
+        // The name of the request header that will be used to obtain the hash key.
+        // Only valid if type is HEADER.
+        @Nullable
+        abstract String headerName();
+
+        // The regular expression used to find portions to be replaced in the header value.
+        // Only valid if type is HEADER.
+        @Nullable
+        abstract Pattern regEx();
+
+        // The string that should be substituted into matching portions of the header value.
+        // Only valid if type is HEADER.
+        @Nullable
+        abstract String regExSubstitution();
+
+        static HashPolicy forHeader(boolean isTerminal, String headerName,
+            @Nullable Pattern regEx, @Nullable String regExSubstitution) {
+          checkNotNull(headerName, "headerName");
+          return HashPolicy.create(Type.HEADER, isTerminal, headerName, regEx, regExSubstitution);
+        }
+
+        static HashPolicy forChannelId(boolean isTerminal) {
+          return HashPolicy.create(Type.CHANNEL_ID, isTerminal, null, null, null);
+        }
+
+        private static HashPolicy create(Type type, boolean isTerminal, @Nullable String headerName,
+            @Nullable Pattern regEx, @Nullable String regExSubstitution) {
+          return new AutoValue_VirtualHost_Route_RouteAction_HashPolicy(type, isTerminal,
+              headerName, regEx, regExSubstitution);
+        }
+
+        enum Type {
+          HEADER, CHANNEL_ID
+        }
+      }
     }
   }
 }

xds/src/main/java/io/grpc/xds/XdsClient.java

@@ -19,8 +19,10 @@ package io.grpc.xds;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
+import com.google.auto.value.AutoValue;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.MoreObjects.ToStringHelper;
+import com.google.common.collect.ImmutableList;
 import io.grpc.Status;
 import io.grpc.xds.Endpoints.DropOverload;
 import io.grpc.xds.Endpoints.LocalityLbEndpoints;
@@ -155,197 +157,155 @@ abstract class XdsClient {
     }
   }
 
-  static final class CdsUpdate implements ResourceUpdate {
+  /** xDS resource update for cluster-level configuration. */
-    final String clusterName;
+  @AutoValue
-    final ClusterType clusterType;
+  abstract static class CdsUpdate implements ResourceUpdate {
-    final ClusterConfig clusterConfig;
+    abstract String clusterName();
 
-    CdsUpdate(String clusterName, ClusterType clusterType, ClusterConfig clusterConfig) {
+    abstract ClusterType clusterType();
-      this.clusterName = checkNotNull(clusterName, "clusterName");
+
-      this.clusterType = checkNotNull(clusterType, "clusterType");
+    // Endpoint-level load balancing policy.
-      this.clusterConfig = checkNotNull(clusterConfig, "clusterConfig");
+    abstract String lbPolicy();
+
+    // Only valid if lbPolicy is "ring_hash".
+    abstract long minRingSize();
+
+    // Only valid if lbPolicy is "ring_hash".
+    abstract long maxRingSize();
+
+    // Only valid if lbPolicy is "ring_hash".
+    @Nullable
+    abstract HashFunction hashFunction();
+
+    // Alternative resource name to be used in EDS requests.
+    /// Only valid for EDS cluster.
+    @Nullable
+    abstract String edsServiceName();
+
+    // Load report server name for reporting loads via LRS.
+    // Only valid for EDS or LOGICAL_DNS cluster.
+    @Nullable
+    abstract String lrsServerName();
+
+    // Max number of concurrent requests can be sent to this cluster.
+    // Only valid for EDS or LOGICAL_DNS cluster.
+    @Nullable
+    abstract Long maxConcurrentRequests();
+
+    // TLS context used to connect to connect to this cluster.
+    // Only valid for EDS or LOGICAL_DNS cluster.
+    @Nullable
+    abstract UpstreamTlsContext upstreamTlsContext();
+
+    // List of underlying clusters making of this aggregate cluster.
+    // Only valid for AGGREGATE cluster.
+    @Nullable
+    abstract ImmutableList<String> prioritizedClusterNames();
+
+    static Builder forAggregate(String clusterName, List<String> prioritizedClusterNames) {
+      checkNotNull(prioritizedClusterNames, "prioritizedClusterNames");
+      return new AutoValue_XdsClient_CdsUpdate.Builder()
+          .clusterName(clusterName)
+          .clusterType(ClusterType.AGGREGATE)
+          .minRingSize(0)
+          .maxRingSize(0)
+          .prioritizedClusterNames(ImmutableList.copyOf(prioritizedClusterNames));
     }
 
-    @Override
+    static Builder forEds(String clusterName, @Nullable String edsServiceName,
-    public int hashCode() {
+        @Nullable String lrsServerName, @Nullable Long maxConcurrentRequests,
-      return Objects.hash(clusterName, clusterType, clusterConfig);
+        @Nullable UpstreamTlsContext upstreamTlsContext) {
+      return new AutoValue_XdsClient_CdsUpdate.Builder()
+          .clusterName(clusterName)
+          .clusterType(ClusterType.EDS)
+          .minRingSize(0)
+          .maxRingSize(0)
+          .edsServiceName(edsServiceName)
+          .lrsServerName(lrsServerName)
+          .maxConcurrentRequests(maxConcurrentRequests)
+          .upstreamTlsContext(upstreamTlsContext);
     }
 
-    @Override
+    static Builder forLogicalDns(String clusterName, @Nullable String lrsServerName,
-    public boolean equals(Object o) {
+        @Nullable Long maxConcurrentRequests, @Nullable UpstreamTlsContext upstreamTlsContext) {
-      if (this == o) {
+      return new AutoValue_XdsClient_CdsUpdate.Builder()
-        return true;
+          .clusterName(clusterName)
-      }
+          .clusterType(ClusterType.LOGICAL_DNS)
-      if (o == null || getClass() != o.getClass()) {
+          .minRingSize(0)
-        return false;
+          .maxRingSize(0)
-      }
+          .lrsServerName(lrsServerName)
-      CdsUpdate that = (CdsUpdate) o;
+          .maxConcurrentRequests(maxConcurrentRequests)
-      return Objects.equals(clusterName, that.clusterName)
+          .upstreamTlsContext(upstreamTlsContext);
-          && Objects.equals(clusterType, that.clusterType)
-          && Objects.equals(clusterConfig, that.clusterConfig);
-    }
-
-    @Override
-    public String toString() {
-      return MoreObjects.toStringHelper(this)
-          .add("clusterName", clusterName)
-          .add("clusterType", clusterType)
-          .add("clusterConfig", clusterConfig)
-          .toString();
     }
 
     enum ClusterType {
       EDS, LOGICAL_DNS, AGGREGATE
     }
 
-    abstract static class ClusterConfig {
+    enum HashFunction {
-      // Endpoint level load balancing policy.
+      XX_HASH
-      final String lbPolicy;
-
-      private ClusterConfig(String lbPolicy) {
-        this.lbPolicy = checkNotNull(lbPolicy, "lbPolicy");
-      }
     }
 
-    static final class AggregateClusterConfig extends ClusterConfig {
+    // FIXME(chengyuanzhang): delete this after UpstreamTlsContext's toString() is fixed.
-      // List of underlying clusters making of this aggregate cluster.
+    @Override
-      final List<String> prioritizedClusterNames;
+    public final String toString() {
-
+      return MoreObjects.toStringHelper(this)
-      AggregateClusterConfig(String lbPolicy, List<String> prioritizedClusterNames) {
+          .add("clusterName", clusterName())
-        super(lbPolicy);
+          .add("clusterType", clusterType())
-        this.prioritizedClusterNames =
+          .add("lbPolicy", lbPolicy())
-            Collections.unmodifiableList(new ArrayList<>(prioritizedClusterNames));
+          .add("minRingSize", minRingSize())
-      }
+          .add("maxRingSize", maxRingSize())
-
+          .add("hashFunction", hashFunction())
-      @Override
+          .add("edsServiceName", edsServiceName())
-      public int hashCode() {
+          .add("lrsServerName", lrsServerName())
-        return Objects.hash(lbPolicy, prioritizedClusterNames);
+          .add("maxConcurrentRequests", maxConcurrentRequests())
-      }
+          // Exclude upstreamTlsContext as its string representation is cumbersome.
-
+          .add("prioritizedClusterNames", prioritizedClusterNames())
-      @Override
+          .toString();
-      public boolean equals(Object o) {
-        if (this == o) {
-          return true;
-        }
-        if (o == null || getClass() != o.getClass()) {
-          return false;
-        }
-        AggregateClusterConfig that = (AggregateClusterConfig) o;
-        return Objects.equals(lbPolicy, that.lbPolicy)
-            && Objects.equals(prioritizedClusterNames, that.prioritizedClusterNames);
-      }
-
-      @Override
-      public String toString() {
-        return MoreObjects.toStringHelper(this)
-            .add("lbPolicy", lbPolicy)
-            .add("prioritizedClusterNames", prioritizedClusterNames)
-            .toString();
-      }
     }
 
-    private abstract static class NonAggregateClusterConfig extends ClusterConfig {
+    @AutoValue.Builder
-      // Load report server name for reporting loads via LRS.
+    abstract static class Builder {
-      @Nullable
+      // Private do not use.
-      final String lrsServerName;
+      protected abstract Builder clusterName(String clusterName);
-      // Max number of concurrent requests can be sent to this cluster.
-      // FIXME(chengyuanzhang): protobuf uint32 is int in Java, so this field can be Integer.
-      @Nullable
-      final Long maxConcurrentRequests;
-      // TLS context used to connect to connect to this cluster.
-      @Nullable
-      final UpstreamTlsContext upstreamTlsContext;
 
-      private NonAggregateClusterConfig(String lbPolicy, @Nullable String lrsServerName,
+      // Private do not use.
-          @Nullable Long maxConcurrentRequests, @Nullable UpstreamTlsContext upstreamTlsContext) {
+      protected abstract Builder clusterType(ClusterType clusterType);
-        super(lbPolicy);
-        this.lrsServerName = lrsServerName;
-        this.maxConcurrentRequests = maxConcurrentRequests;
-        this.upstreamTlsContext = upstreamTlsContext;
-      }
-    }
 
-    static final class EdsClusterConfig extends NonAggregateClusterConfig {
+      // Private do not use.
-      // Alternative resource name to be used in EDS requests.
+      protected abstract Builder lbPolicy(String lbPolicy);
-      @Nullable
-      final String edsServiceName;
 
-      EdsClusterConfig(String lbPolicy, @Nullable String edsServiceName,
+      Builder lbPolicy(String lbPolicy, long minRingSize, long maxRingSize,
-          @Nullable String lrsServerName, @Nullable Long maxConcurrentRequests,
+          HashFunction hashFunction) {
-          @Nullable UpstreamTlsContext upstreamTlsContext) {
+        return this.lbPolicy(lbPolicy).minRingSize(minRingSize).maxRingSize(maxRingSize)
-        super(lbPolicy, lrsServerName, maxConcurrentRequests, upstreamTlsContext);
+            .hashFunction(checkNotNull(hashFunction, "hashFunction"));
-        this.edsServiceName = edsServiceName;
       }
 
-      @Override
+      // Private do not use.
-      public int hashCode() {
+      protected abstract Builder minRingSize(long minRingSize);
-        return Objects.hash(lbPolicy, edsServiceName, lrsServerName, maxConcurrentRequests,
-            upstreamTlsContext);
-      }
 
-      @Override
+      // Private do not use.
-      public boolean equals(Object o) {
+      protected abstract Builder maxRingSize(long maxRingSize);
-        if (this == o) {
-          return true;
-        }
-        if (o == null || getClass() != o.getClass()) {
-          return false;
-        }
-        EdsClusterConfig that = (EdsClusterConfig) o;
-        return Objects.equals(lbPolicy, that.lbPolicy)
-            && Objects.equals(edsServiceName, that.edsServiceName)
-            && Objects.equals(lrsServerName, that.lrsServerName)
-            && Objects.equals(maxConcurrentRequests, that.maxConcurrentRequests)
-            && Objects.equals(upstreamTlsContext, that.upstreamTlsContext);
-      }
 
-      @Override
+      // Private do not use.
-      public String toString() {
+      protected abstract Builder hashFunction(HashFunction hashFunction);
-        return MoreObjects.toStringHelper(this)
-            .add("lbPolicy", lbPolicy)
-            .add("edsServiceName", edsServiceName)
-            .add("lrsServerName", lrsServerName)
-            .add("maxConcurrentRequests", maxConcurrentRequests)
-            // Exclude upstreamTlsContext as its string representation is cumbersome.
-            .toString();
-      }
-    }
 
-    static final class LogicalDnsClusterConfig extends NonAggregateClusterConfig {
+      // Private do not use.
-      LogicalDnsClusterConfig(String lbPolicy, @Nullable String lrsServerName,
+      protected abstract Builder edsServiceName(String edsServiceName);
-          @Nullable Long maxConcurrentRequests, @Nullable UpstreamTlsContext upstreamTlsContext) {
-        super(lbPolicy, lrsServerName, maxConcurrentRequests, upstreamTlsContext);
-      }
 
-      @Override
+      // Private do not use.
-      public int hashCode() {
+      protected abstract Builder lrsServerName(String lrsServerName);
-        return Objects.hash(lbPolicy, lrsServerName, maxConcurrentRequests, upstreamTlsContext);
-      }
 
-      @Override
+      // Private do not use.
-      public boolean equals(Object o) {
+      protected abstract Builder maxConcurrentRequests(Long maxConcurrentRequests);
-        if (this == o) {
-          return true;
-        }
-        if (o == null || getClass() != o.getClass()) {
-          return false;
-        }
-        LogicalDnsClusterConfig that = (LogicalDnsClusterConfig) o;
-        return Objects.equals(lbPolicy, that.lbPolicy)
-            && Objects.equals(lrsServerName, that.lrsServerName)
-            && Objects.equals(maxConcurrentRequests, that.maxConcurrentRequests)
-            && Objects.equals(upstreamTlsContext, that.upstreamTlsContext);
-      }
 
-      @Override
+      // Private do not use.
-      public String toString() {
+      protected abstract Builder upstreamTlsContext(UpstreamTlsContext upstreamTlsContext);
-        return MoreObjects.toStringHelper(this)
+
-            .add("lbPolicy", lbPolicy)
+      // Private do not use.
-            .add("lrsServerName", lrsServerName)
+      protected abstract Builder prioritizedClusterNames(List<String> prioritizedClusterNames);
-            .add("maxConcurrentRequests", maxConcurrentRequests)
+
-            // Exclude upstreamTlsContext as its string representation is cumbersome.
+      abstract CdsUpdate build();
-            .toString();
-      }
     }
   }
 

xds/src/test/java/io/grpc/xds/CdsLoadBalancer2Test.java

@@ -47,10 +47,6 @@ import io.grpc.xds.CdsLoadBalancerProvider.CdsConfig;
 import io.grpc.xds.ClusterResolverLoadBalancerProvider.ClusterResolverConfig;
 import io.grpc.xds.ClusterResolverLoadBalancerProvider.ClusterResolverConfig.DiscoveryMechanism;
 import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
-import io.grpc.xds.XdsClient.CdsUpdate.AggregateClusterConfig;
-import io.grpc.xds.XdsClient.CdsUpdate.ClusterType;
-import io.grpc.xds.XdsClient.CdsUpdate.EdsClusterConfig;
-import io.grpc.xds.XdsClient.CdsUpdate.LogicalDnsClusterConfig;
 import io.grpc.xds.internal.sds.CommonTlsContextTestsUtil;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -548,9 +544,9 @@ public class CdsLoadBalancer2Test {
         @Nullable String lrsServerName, @Nullable Long maxConcurrentRequests,
         @Nullable UpstreamTlsContext tlsContext) {
       if (watchers.containsKey(clusterName)) {
-        EdsClusterConfig clusterConfig = new EdsClusterConfig("round_robin", edsServiceName,
+        CdsUpdate update = CdsUpdate.forEds(
-            lrsServerName, maxConcurrentRequests, tlsContext);
+            clusterName, edsServiceName, lrsServerName, maxConcurrentRequests, tlsContext)
-        CdsUpdate update = new CdsUpdate(clusterName, ClusterType.EDS, clusterConfig);
+            .lbPolicy("round_robin").build();
         watchers.get(clusterName).onChanged(update);
       }
     }
@@ -558,17 +554,17 @@ public class CdsLoadBalancer2Test {
     private void deliverLogicalDnsCluster(String clusterName, @Nullable String lrsServerName,
         @Nullable Long maxConcurrentRequests, @Nullable UpstreamTlsContext tlsContext) {
       if (watchers.containsKey(clusterName)) {
-        LogicalDnsClusterConfig clusterConfig = new LogicalDnsClusterConfig("round_robin",
+        CdsUpdate update = CdsUpdate.forLogicalDns(
-            lrsServerName, maxConcurrentRequests, tlsContext);
+            clusterName, lrsServerName, maxConcurrentRequests, tlsContext)
-        CdsUpdate update = new CdsUpdate(clusterName, ClusterType.LOGICAL_DNS, clusterConfig);
+            .lbPolicy("round_robin").build();
         watchers.get(clusterName).onChanged(update);
       }
     }
 
     private void deliverAggregateCluster(String clusterName, List<String> clusters) {
       if (watchers.containsKey(clusterName)) {
-        AggregateClusterConfig clusterConfig = new AggregateClusterConfig("round_robin", clusters);
+        CdsUpdate update = CdsUpdate.forAggregate(clusterName, clusters)
-        CdsUpdate update = new CdsUpdate(clusterName, ClusterType.AGGREGATE, clusterConfig);
+            .lbPolicy("round_robin").build();
         watchers.get(clusterName).onChanged(update);
       }
     }

xds/src/test/java/io/grpc/xds/ClientXdsClientDataTest.java

@@ -29,10 +29,16 @@ import io.envoyproxy.envoy.config.endpoint.v3.Endpoint;
 import io.envoyproxy.envoy.config.route.v3.DirectResponseAction;
 import io.envoyproxy.envoy.config.route.v3.FilterAction;
 import io.envoyproxy.envoy.config.route.v3.RedirectAction;
+import io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.ConnectionProperties;
+import io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.FilterState;
+import io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.Header;
+import io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.QueryParameter;
 import io.envoyproxy.envoy.config.route.v3.RouteAction.MaxStreamDuration;
 import io.envoyproxy.envoy.config.route.v3.WeightedCluster;
 import io.envoyproxy.envoy.extensions.filters.http.fault.v3.FaultAbort.HeaderAbort;
+import io.envoyproxy.envoy.type.matcher.v3.RegexMatchAndSubstitute;
 import io.envoyproxy.envoy.type.matcher.v3.RegexMatcher;
+import io.envoyproxy.envoy.type.matcher.v3.RegexMatcher.GoogleRE2;
 import io.envoyproxy.envoy.type.v3.FractionalPercent;
 import io.envoyproxy.envoy.type.v3.FractionalPercent.DenominatorType;
 import io.envoyproxy.envoy.type.v3.Int64Range;
@@ -47,9 +53,11 @@ import io.grpc.xds.Matchers.PathMatcher;
 import io.grpc.xds.VirtualHost.Route;
 import io.grpc.xds.VirtualHost.Route.RouteAction;
 import io.grpc.xds.VirtualHost.Route.RouteAction.ClusterWeight;
+import io.grpc.xds.VirtualHost.Route.RouteAction.HashPolicy;
 import io.grpc.xds.VirtualHost.Route.RouteMatch;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -77,7 +85,8 @@ public class ClientXdsClientDataTest {
             Route.create(
                 RouteMatch.create(PathMatcher.fromPath("/service/method", false),
                     Collections.<HeaderMatcher>emptyList(), null),
-                RouteAction.forCluster("cluster-foo", null), null));
+                RouteAction.forCluster("cluster-foo", Collections.<HashPolicy>emptyList(), null),
+                null));
   }
 
   @Test
@@ -390,6 +399,50 @@ public class ClientXdsClientDataTest {
     assertThat(struct.getStruct().timeoutNano()).isNull();
   }
 
+  @Test
+  public void parseRouteAction_withHashPolicies() {
+    io.envoyproxy.envoy.config.route.v3.RouteAction proto =
+        io.envoyproxy.envoy.config.route.v3.RouteAction.newBuilder()
+            .setCluster("cluster-foo")
+            .addHashPolicy(
+                io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.newBuilder()
+                    .setHeader(
+                        Header.newBuilder()
+                            .setHeaderName("user-agent")
+                            .setRegexRewrite(
+                                RegexMatchAndSubstitute.newBuilder()
+                                    .setPattern(
+                                        RegexMatcher.newBuilder()
+                                            .setGoogleRe2(GoogleRE2.getDefaultInstance())
+                                            .setRegex("grpc.*"))
+                                    .setSubstitution("gRPC"))))
+            .addHashPolicy(
+                io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.newBuilder()
+                    .setConnectionProperties(ConnectionProperties.newBuilder().setSourceIp(true))
+                    .setTerminal(true))  // unsupported
+            .addHashPolicy(
+                io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.newBuilder()
+                    .setFilterState(
+                        FilterState.newBuilder()
+                            .setKey(ClientXdsClient.HASH_POLICY_FILTER_STATE_KEY)))
+            .addHashPolicy(
+                io.envoyproxy.envoy.config.route.v3.RouteAction.HashPolicy.newBuilder()
+                    .setQueryParameter(
+                        QueryParameter.newBuilder().setName("param"))) // unsupported
+            .build();
+    StructOrError<RouteAction> struct = ClientXdsClient.parseRouteAction(proto);
+    List<HashPolicy> policies = struct.getStruct().hashPolicies();
+    assertThat(policies).hasSize(2);
+    assertThat(policies.get(0).type()).isEqualTo(HashPolicy.Type.HEADER);
+    assertThat(policies.get(0).headerName()).isEqualTo("user-agent");
+    assertThat(policies.get(0).isTerminal()).isFalse();
+    assertThat(policies.get(0).regEx().pattern()).isEqualTo("grpc.*");
+    assertThat(policies.get(0).regExSubstitution()).isEqualTo("gRPC");
+
+    assertThat(policies.get(1).type()).isEqualTo(HashPolicy.Type.CHANNEL_ID);
+    assertThat(policies.get(1).isTerminal()).isFalse();
+  }
+
   @Test
   public void parseClusterWeight() {
     io.envoyproxy.envoy.config.route.v3.WeightedCluster.ClusterWeight proto =

xds/src/test/java/io/grpc/xds/ClientXdsClientTestBase.java

@@ -47,14 +47,11 @@ import io.grpc.xds.Endpoints.DropOverload;
 import io.grpc.xds.Endpoints.LbEndpoint;
 import io.grpc.xds.Endpoints.LocalityLbEndpoints;
 import io.grpc.xds.EnvoyProtoData.Node;
-import io.grpc.xds.EnvoyServerProtoData.UpstreamTlsContext;
 import io.grpc.xds.LoadStatsManager2.ClusterDropStats;
 import io.grpc.xds.XdsClient.CdsResourceWatcher;
 import io.grpc.xds.XdsClient.CdsUpdate;
-import io.grpc.xds.XdsClient.CdsUpdate.AggregateClusterConfig;
 import io.grpc.xds.XdsClient.CdsUpdate.ClusterType;
-import io.grpc.xds.XdsClient.CdsUpdate.EdsClusterConfig;
+import io.grpc.xds.XdsClient.CdsUpdate.HashFunction;
-import io.grpc.xds.XdsClient.CdsUpdate.LogicalDnsClusterConfig;
 import io.grpc.xds.XdsClient.EdsResourceWatcher;
 import io.grpc.xds.XdsClient.EdsUpdate;
 import io.grpc.xds.XdsClient.LdsResourceWatcher;
@@ -597,8 +594,10 @@ public abstract class ClientXdsClientTestBase {
         startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
 
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster("cluster-bar.googleapis.com", null, false, null, null)),
+        Any.pack(mf.buildEdsCluster("cluster-bar.googleapis.com", null, "round_robin", null,
-        Any.pack(mf.buildEdsCluster("cluster-baz.googleapis.com", null, false, null, null)));
+            false, null, null)),
+        Any.pack(mf.buildEdsCluster("cluster-baz.googleapis.com", null, "round_robin", null,
+            false, null, null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sent an ACK CDS request.
@@ -616,7 +615,7 @@ public abstract class ClientXdsClientTestBase {
     DiscoveryRpcCall call =
         startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, false, null, null)));
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, "round_robin", null, false, null, null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sent an ACK CDS request.
@@ -624,14 +623,41 @@ public abstract class ClientXdsClientTestBase {
         "0000");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    EdsClusterConfig clusterConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isNull();
-    assertThat(clusterConfig.edsServiceName).isNull();
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(clusterConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isNull();
-    assertThat(clusterConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(clusterConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(clusterConfig.upstreamTlsContext).isNull();
+    assertThat(fakeClock.getPendingTasks(CDS_RESOURCE_FETCH_TIMEOUT_TASK_FILTER)).isEmpty();
+  }
+
+  @Test
+  public void cdsResourceFound_ringHashLbPolicy() {
+    DiscoveryRpcCall call =
+        startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
+    Message ringHashConfig = mf.buildRingHashLbConfig("xx_hash", 10L, 100L);
+    List<Any> clusters = ImmutableList.of(
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, "ring_hash", ringHashConfig, false, null,
+            null)));
+    call.sendResponse("0", clusters, ResourceType.CDS, "0000");
+
+    // Client sent an ACK CDS request.
+    call.verifyRequest(NODE, "0", Collections.singletonList(CDS_RESOURCE), ResourceType.CDS,
+        "0000");
+    verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
+    CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.edsServiceName()).isNull();
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("ring_hash");
+    assertThat(cdsUpdate.hashFunction()).isEqualTo(HashFunction.XX_HASH);
+    assertThat(cdsUpdate.minRingSize()).isEqualTo(10L);
+    assertThat(cdsUpdate.maxRingSize()).isEqualTo(100L);
+    assertThat(cdsUpdate.lrsServerName()).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
     assertThat(fakeClock.getPendingTasks(CDS_RESOURCE_FETCH_TIMEOUT_TASK_FILTER)).isEmpty();
   }
 
@@ -642,7 +668,7 @@ public abstract class ClientXdsClientTestBase {
     List<String> candidates = Arrays.asList(
         "cluster1.googleapis.com", "cluster2.googleapis.com", "cluster3.googleapis.com");
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildAggregateCluster(CDS_RESOURCE, candidates)));
+        Any.pack(mf.buildAggregateCluster(CDS_RESOURCE, "round_robin", null, candidates)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sent an ACK CDS request.
@@ -650,12 +676,10 @@ public abstract class ClientXdsClientTestBase {
         "0000");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.AGGREGATE);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.AGGREGATE);
-    AggregateClusterConfig clusterConfig = (AggregateClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(clusterConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.prioritizedClusterNames()).containsExactlyElementsIn(candidates).inOrder();
-    assertThat(clusterConfig.prioritizedClusterNames)
-        .containsExactlyElementsIn(candidates).inOrder();
   }
 
   @Test
@@ -663,7 +687,7 @@ public abstract class ClientXdsClientTestBase {
     DiscoveryRpcCall call =
         startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, false, null,
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, "round_robin", null, false, null,
             mf.buildCircuitBreakers(50, 200))));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
@@ -672,14 +696,13 @@ public abstract class ClientXdsClientTestBase {
         "0000");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    EdsClusterConfig clusterConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isNull();
-    assertThat(clusterConfig.edsServiceName).isNull();
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(clusterConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isNull();
-    assertThat(clusterConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isEqualTo(200L);
-    assertThat(clusterConfig.maxConcurrentRequests).isEqualTo(200L);
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(clusterConfig.upstreamTlsContext).isNull();
   }
 
   /**
@@ -692,10 +715,13 @@ public abstract class ClientXdsClientTestBase {
 
     // Management server sends back CDS response with UpstreamTlsContext.
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildLogicalDnsCluster("cluster-bar.googleapis.com", false, null, null)),
+        Any.pack(mf.buildLogicalDnsCluster("cluster-bar.googleapis.com", "round_robin", null,
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, "eds-cluster-foo.googleapis.com", true,
+            false, null, null)),
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, "eds-cluster-foo.googleapis.com", "round_robin",
+            null, true,
             mf.buildUpstreamTlsContext("secret1", "unix:/var/uds2"), null)),
-        Any.pack(mf.buildEdsCluster("cluster-baz.googleapis.com", null, false, null, null)));
+        Any.pack(mf.buildEdsCluster("cluster-baz.googleapis.com", null, "round_robin", null, false,
+            null, null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sent an ACK CDS request.
@@ -703,10 +729,8 @@ public abstract class ClientXdsClientTestBase {
         "0000");
     verify(cdsResourceWatcher, times(1)).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    UpstreamTlsContext upstreamTlsContext =
+    SdsSecretConfig validationContextSdsSecretConfig =
-        ((EdsClusterConfig) cdsUpdate.clusterConfig).upstreamTlsContext;
+        cdsUpdate.upstreamTlsContext().getCommonTlsContext().getValidationContextSdsSecretConfig();
-    SdsSecretConfig validationContextSdsSecretConfig = upstreamTlsContext.getCommonTlsContext()
-        .getValidationContextSdsSecretConfig();
     assertThat(validationContextSdsSecretConfig.getName()).isEqualTo("secret1");
     assertThat(
         Iterables.getOnlyElement(
@@ -724,7 +748,7 @@ public abstract class ClientXdsClientTestBase {
     DiscoveryRpcCall call =
         startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, false, null, null)));
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, "round_robin", null, false, null, null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sends an ACK CDS request.
@@ -735,14 +759,13 @@ public abstract class ClientXdsClientTestBase {
     xdsClient.watchCdsResource(CDS_RESOURCE, watcher);
     verify(watcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    EdsClusterConfig clusterConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isNull();
-    assertThat(clusterConfig.edsServiceName).isNull();
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(clusterConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isNull();
-    assertThat(clusterConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(clusterConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(clusterConfig.upstreamTlsContext).isNull();
     call.verifyNoMoreRequest();
   }
 
@@ -763,7 +786,7 @@ public abstract class ClientXdsClientTestBase {
     DiscoveryRpcCall call =
         startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildLogicalDnsCluster(CDS_RESOURCE, false, null, null)));
+        Any.pack(mf.buildLogicalDnsCluster(CDS_RESOURCE, "round_robin", null, false, null, null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sends an ACK CDS request.
@@ -771,17 +794,17 @@ public abstract class ClientXdsClientTestBase {
         "0000");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.LOGICAL_DNS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.LOGICAL_DNS);
-    LogicalDnsClusterConfig dnsConfig = (LogicalDnsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(dnsConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isNull();
-    assertThat(dnsConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(dnsConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(dnsConfig.upstreamTlsContext).isNull();
 
     String edsService = "eds-service-bar.googleapis.com";
     clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, edsService, true, null, null)));
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, edsService, "round_robin", null, true, null,
+            null)));
     call.sendResponse("1", clusters, ResourceType.CDS, "0001");
 
     // Client sends an ACK CDS request.
@@ -789,14 +812,13 @@ public abstract class ClientXdsClientTestBase {
         "0001");
     verify(cdsResourceWatcher, times(2)).onChanged(cdsUpdateCaptor.capture());
     cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    EdsClusterConfig edsConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isEqualTo(edsService);
-    assertThat(edsConfig.edsServiceName).isEqualTo(edsService);
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(edsConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isEqualTo("");
-    assertThat(edsConfig.lrsServerName).isEqualTo("");
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(edsConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(edsConfig.upstreamTlsContext).isNull();
   }
 
   @Test
@@ -804,7 +826,7 @@ public abstract class ClientXdsClientTestBase {
     DiscoveryRpcCall call =
         startResourceWatcher(ResourceType.CDS, CDS_RESOURCE, cdsResourceWatcher);
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, false, null, null)));
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, "round_robin", null, false, null, null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
 
     // Client sends an ACK CDS request.
@@ -812,14 +834,13 @@ public abstract class ClientXdsClientTestBase {
         "0000");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    EdsClusterConfig clusterConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isNull();
-    assertThat(clusterConfig.edsServiceName).isNull();
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(clusterConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isNull();
-    assertThat(clusterConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(clusterConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(clusterConfig.upstreamTlsContext).isNull();
 
     call.sendResponse("1", Collections.<Any>emptyList(), ResourceType.CDS, "0001");
 
@@ -847,38 +868,36 @@ public abstract class ClientXdsClientTestBase {
 
     String edsService = "eds-service-bar.googleapis.com";
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildLogicalDnsCluster(CDS_RESOURCE, false, null, null)),
+        Any.pack(mf.buildLogicalDnsCluster(CDS_RESOURCE, "round_robin", null, false, null, null)),
-        Any.pack(mf.buildEdsCluster(cdsResource, edsService, true, null, null)));
+        Any.pack(mf.buildEdsCluster(cdsResource, edsService, "round_robin", null, true, null,
+            null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
     CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(CDS_RESOURCE);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(CDS_RESOURCE);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.LOGICAL_DNS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.LOGICAL_DNS);
-    LogicalDnsClusterConfig dnsConfig = (LogicalDnsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(dnsConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isNull();
-    assertThat(dnsConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(dnsConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(dnsConfig.upstreamTlsContext).isNull();
     verify(watcher1).onChanged(cdsUpdateCaptor.capture());
     cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(cdsResource);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(cdsResource);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    EdsClusterConfig edsConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isEqualTo(edsService);
-    assertThat(edsConfig.edsServiceName).isEqualTo(edsService);
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(edsConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isEqualTo("");
-    assertThat(edsConfig.lrsServerName).isEqualTo("");
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(edsConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(edsConfig.upstreamTlsContext).isNull();
     verify(watcher2).onChanged(cdsUpdateCaptor.capture());
     cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(cdsUpdate.clusterName).isEqualTo(cdsResource);
+    assertThat(cdsUpdate.clusterName()).isEqualTo(cdsResource);
-    assertThat(cdsUpdate.clusterType).isEqualTo(ClusterType.EDS);
+    assertThat(cdsUpdate.clusterType()).isEqualTo(ClusterType.EDS);
-    edsConfig = (EdsClusterConfig) cdsUpdate.clusterConfig;
+    assertThat(cdsUpdate.edsServiceName()).isEqualTo(edsService);
-    assertThat(edsConfig.edsServiceName).isEqualTo(edsService);
+    assertThat(cdsUpdate.lbPolicy()).isEqualTo("round_robin");
-    assertThat(edsConfig.lbPolicy).isEqualTo("round_robin");
+    assertThat(cdsUpdate.lrsServerName()).isEqualTo("");
-    assertThat(edsConfig.lrsServerName).isEqualTo("");
+    assertThat(cdsUpdate.maxConcurrentRequests()).isNull();
-    assertThat(edsConfig.maxConcurrentRequests).isNull();
+    assertThat(cdsUpdate.upstreamTlsContext()).isNull();
-    assertThat(edsConfig.upstreamTlsContext).isNull();
   }
 
   @Test
@@ -1094,17 +1113,18 @@ public abstract class ClientXdsClientTestBase {
     xdsClient.watchEdsResource(EDS_RESOURCE, edsResourceWatcher);
     DiscoveryRpcCall call = resourceDiscoveryCalls.poll();
     List<Any> clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(resource, null, true, null, null)),
+        Any.pack(mf.buildEdsCluster(resource, null, "round_robin", null, true, null, null)),
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, EDS_RESOURCE, false, null, null)));
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, EDS_RESOURCE, "round_robin", null, false, null,
+            null)));
     call.sendResponse("0", clusters, ResourceType.CDS, "0000");
     verify(cdsWatcher).onChanged(cdsUpdateCaptor.capture());
-    EdsClusterConfig clusterConfig = (EdsClusterConfig) cdsUpdateCaptor.getValue().clusterConfig;
+    CdsUpdate cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(clusterConfig.edsServiceName).isEqualTo(null);
+    assertThat(cdsUpdate.edsServiceName()).isEqualTo(null);
-    assertThat(clusterConfig.lrsServerName).isEqualTo("");
+    assertThat(cdsUpdate.lrsServerName()).isEqualTo("");
     verify(cdsResourceWatcher).onChanged(cdsUpdateCaptor.capture());
-    clusterConfig = (EdsClusterConfig) cdsUpdateCaptor.getValue().clusterConfig;
+    cdsUpdate = cdsUpdateCaptor.getValue();
-    assertThat(clusterConfig.edsServiceName).isEqualTo(EDS_RESOURCE);
+    assertThat(cdsUpdate.edsServiceName()).isEqualTo(EDS_RESOURCE);
-    assertThat(clusterConfig.lrsServerName).isNull();
+    assertThat(cdsUpdate.lrsServerName()).isNull();
 
     List<Any> clusterLoadAssignments =
         ImmutableList.of(
@@ -1134,12 +1154,12 @@ public abstract class ClientXdsClientTestBase {
     assertThat(edsUpdateCaptor.getValue().clusterName).isEqualTo(EDS_RESOURCE);
 
     clusters = ImmutableList.of(
-        Any.pack(mf.buildEdsCluster(resource, null, true, null, null)),  // no change
+        Any.pack(mf.buildEdsCluster(resource, null, "round_robin", null, true, null,
-        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, false, null, null)));
+            null)),  // no change
+        Any.pack(mf.buildEdsCluster(CDS_RESOURCE, null, "round_robin", null, false, null, null)));
     call.sendResponse("1", clusters, ResourceType.CDS, "0001");
     verify(cdsResourceWatcher, times(2)).onChanged(cdsUpdateCaptor.capture());
-    clusterConfig = (EdsClusterConfig) cdsUpdateCaptor.getValue().clusterConfig;
+    assertThat(cdsUpdateCaptor.getValue().edsServiceName()).isNull();
-    assertThat(clusterConfig.edsServiceName).isNull();
     verify(edsResourceWatcher).onResourceDoesNotExist(EDS_RESOURCE);
     verifyNoMoreInteractions(cdsWatcher, edsWatcher);
   }
@@ -1535,13 +1555,18 @@ public abstract class ClientXdsClientTestBase {
     protected abstract List<? extends Message> buildOpaqueRoutes(int num);
 
     protected abstract Message buildEdsCluster(String clusterName, @Nullable String edsServiceName,
-        boolean enableLrs, @Nullable Message upstreamTlsContext,
+        String lbPolicy, @Nullable Message ringHashLbConfig, boolean enableLrs,
-        @Nullable Message circuitBreakers);
-
-    protected abstract Message buildLogicalDnsCluster(String clusterName, boolean enableLrs,
         @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers);
 
-    protected abstract Message buildAggregateCluster(String clusterName, List<String> clusters);
+    protected abstract Message buildLogicalDnsCluster(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, boolean enableLrs,
+        @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers);
+
+    protected abstract Message buildAggregateCluster(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, List<String> clusters);
+
+    protected abstract Message buildRingHashLbConfig(String hashFunction, long minRingSize,
+        long maxRingSize);
 
     protected abstract Message buildUpstreamTlsContext(String secretName, String targetUri);
 

xds/src/test/java/io/grpc/xds/ClientXdsClientV2Test.java

@@ -27,12 +27,15 @@ import com.google.common.util.concurrent.MoreExecutors;
 import com.google.protobuf.Any;
 import com.google.protobuf.Message;
 import com.google.protobuf.UInt32Value;
+import com.google.protobuf.UInt64Value;
 import com.google.protobuf.util.Durations;
 import io.envoyproxy.envoy.api.v2.Cluster;
 import io.envoyproxy.envoy.api.v2.Cluster.CustomClusterType;
 import io.envoyproxy.envoy.api.v2.Cluster.DiscoveryType;
 import io.envoyproxy.envoy.api.v2.Cluster.EdsClusterConfig;
 import io.envoyproxy.envoy.api.v2.Cluster.LbPolicy;
+import io.envoyproxy.envoy.api.v2.Cluster.RingHashLbConfig;
+import io.envoyproxy.envoy.api.v2.Cluster.RingHashLbConfig.HashFunction;
 import io.envoyproxy.envoy.api.v2.ClusterLoadAssignment;
 import io.envoyproxy.envoy.api.v2.ClusterLoadAssignment.Policy;
 import io.envoyproxy.envoy.api.v2.ClusterLoadAssignment.Policy.DropOverload;
@@ -384,10 +387,10 @@ public class ClientXdsClientV2Test extends ClientXdsClientTestBase {
 
     @Override
     protected Message buildEdsCluster(String clusterName, @Nullable String edsServiceName,
-        boolean enableLrs, @Nullable Message upstreamTlsContext,
+        String lbPolicy, @Nullable Message ringHashLbConfig, boolean enableLrs,
-        @Nullable Message circuitBreakers) {
+        @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers) {
-      Cluster.Builder builder =
+      Cluster.Builder builder = initClusterBuilder(clusterName, lbPolicy, ringHashLbConfig,
-          initClusterBuilder(clusterName, enableLrs, upstreamTlsContext, circuitBreakers);
+          enableLrs, upstreamTlsContext, circuitBreakers);
       builder.setType(DiscoveryType.EDS);
       EdsClusterConfig.Builder edsClusterConfigBuilder = EdsClusterConfig.newBuilder();
       edsClusterConfigBuilder.setEdsConfig(
@@ -400,34 +403,49 @@ public class ClientXdsClientV2Test extends ClientXdsClientTestBase {
     }
 
     @Override
-    protected Message buildLogicalDnsCluster(String clusterName, boolean enableLrs,
+    protected Message buildLogicalDnsCluster(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, boolean enableLrs,
         @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers) {
-      Cluster.Builder builder =
+      Cluster.Builder builder = initClusterBuilder(clusterName, lbPolicy, ringHashLbConfig,
-          initClusterBuilder(clusterName, enableLrs, upstreamTlsContext, circuitBreakers);
+          enableLrs, upstreamTlsContext, circuitBreakers);
       builder.setType(DiscoveryType.LOGICAL_DNS);
       return builder.build();
     }
 
     @Override
-    protected Message buildAggregateCluster(String clusterName, List<String> clusters) {
+    protected Message buildAggregateCluster(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, List<String> clusters) {
       ClusterConfig clusterConfig = ClusterConfig.newBuilder().addAllClusters(clusters).build();
       CustomClusterType type =
           CustomClusterType.newBuilder()
               .setName(ClientXdsClient.AGGREGATE_CLUSTER_TYPE_NAME)
               .setTypedConfig(Any.pack(clusterConfig))
               .build();
-      return Cluster.newBuilder()
+      Cluster.Builder builder = Cluster.newBuilder().setName(clusterName).setClusterType(type);
-          .setName(clusterName)
+      if (lbPolicy.equals("round_robin")) {
-          .setLbPolicy(LbPolicy.ROUND_ROBIN)
+        builder.setLbPolicy(LbPolicy.ROUND_ROBIN);
-          .setClusterType(type)
+      } else if (lbPolicy.equals("ring_hash")) {
-          .build();
+        builder.setLbPolicy(LbPolicy.RING_HASH);
+        builder.setRingHashLbConfig((RingHashLbConfig) ringHashLbConfig);
+      } else {
+        throw new AssertionError("Invalid LB policy");
+      }
+      return builder.build();
     }
 
-    private Cluster.Builder initClusterBuilder(String clusterName, boolean enableLrs,
+    private Cluster.Builder initClusterBuilder(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, boolean enableLrs,
         @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers) {
       Cluster.Builder builder = Cluster.newBuilder();
       builder.setName(clusterName);
-      builder.setLbPolicy(LbPolicy.ROUND_ROBIN);
+      if (lbPolicy.equals("round_robin")) {
+        builder.setLbPolicy(LbPolicy.ROUND_ROBIN);
+      } else if (lbPolicy.equals("ring_hash")) {
+        builder.setLbPolicy(LbPolicy.RING_HASH);
+        builder.setRingHashLbConfig((RingHashLbConfig) ringHashLbConfig);
+      } else {
+        throw new AssertionError("Invalid LB policy");
+      }
       if (enableLrs) {
         builder.setLrsServer(
             ConfigSource.newBuilder()
@@ -445,6 +463,22 @@ public class ClientXdsClientV2Test extends ClientXdsClientTestBase {
       return builder;
     }
 
+    @Override
+    protected Message buildRingHashLbConfig(String hashFunction, long minRingSize,
+        long maxRingSize) {
+      RingHashLbConfig.Builder builder = RingHashLbConfig.newBuilder();
+      if (hashFunction.equals("xx_hash")) {
+        builder.setHashFunction(HashFunction.XX_HASH);
+      } else if  (hashFunction.equals("murmur_hash_2")) {
+        builder.setHashFunction(HashFunction.MURMUR_HASH_2);
+      } else {
+        throw new AssertionError("Invalid hash function");
+      }
+      builder.setMinimumRingSize(UInt64Value.newBuilder().setValue(minRingSize).build());
+      builder.setMaximumRingSize(UInt64Value.newBuilder().setValue(maxRingSize).build());
+      return builder.build();
+    }
+
     @Override
     protected Message buildUpstreamTlsContext(String secretName, String targetUri) {
       GrpcService grpcService =

xds/src/test/java/io/grpc/xds/ClientXdsClientV3Test.java

@@ -27,6 +27,7 @@ import com.google.common.util.concurrent.MoreExecutors;
 import com.google.protobuf.Any;
 import com.google.protobuf.Message;
 import com.google.protobuf.UInt32Value;
+import com.google.protobuf.UInt64Value;
 import com.google.protobuf.util.Durations;
 import io.envoyproxy.envoy.config.cluster.v3.CircuitBreakers;
 import io.envoyproxy.envoy.config.cluster.v3.CircuitBreakers.Thresholds;
@@ -35,6 +36,8 @@ import io.envoyproxy.envoy.config.cluster.v3.Cluster.CustomClusterType;
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.DiscoveryType;
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.EdsClusterConfig;
 import io.envoyproxy.envoy.config.cluster.v3.Cluster.LbPolicy;
+import io.envoyproxy.envoy.config.cluster.v3.Cluster.RingHashLbConfig;
+import io.envoyproxy.envoy.config.cluster.v3.Cluster.RingHashLbConfig.HashFunction;
 import io.envoyproxy.envoy.config.core.v3.Address;
 import io.envoyproxy.envoy.config.core.v3.AggregatedConfigSource;
 import io.envoyproxy.envoy.config.core.v3.ApiConfigSource;
@@ -382,10 +385,10 @@ public class ClientXdsClientV3Test extends ClientXdsClientTestBase {
 
     @Override
     protected Message buildEdsCluster(String clusterName, @Nullable String edsServiceName,
-        boolean enableLrs, @Nullable Message upstreamTlsContext,
+        String lbPolicy, @Nullable Message ringHashLbConfig, boolean enableLrs,
-        @Nullable Message circuitBreakers) {
+        @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers) {
-      Cluster.Builder builder =
+      Cluster.Builder builder = initClusterBuilder(clusterName, lbPolicy, ringHashLbConfig,
-          initClusterBuilder(clusterName, enableLrs, upstreamTlsContext, circuitBreakers);
+          enableLrs, upstreamTlsContext, circuitBreakers);
       builder.setType(DiscoveryType.EDS);
       EdsClusterConfig.Builder edsClusterConfigBuilder = EdsClusterConfig.newBuilder();
       edsClusterConfigBuilder.setEdsConfig(
@@ -398,34 +401,49 @@ public class ClientXdsClientV3Test extends ClientXdsClientTestBase {
     }
 
     @Override
-    protected Message buildLogicalDnsCluster(String clusterName, boolean enableLrs,
+    protected Message buildLogicalDnsCluster(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, boolean enableLrs,
         @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers) {
-      Cluster.Builder builder =
+      Cluster.Builder builder = initClusterBuilder(clusterName, lbPolicy, ringHashLbConfig,
-          initClusterBuilder(clusterName, enableLrs, upstreamTlsContext, circuitBreakers);
+          enableLrs, upstreamTlsContext, circuitBreakers);
       builder.setType(DiscoveryType.LOGICAL_DNS);
       return builder.build();
     }
 
     @Override
-    protected Message buildAggregateCluster(String clusterName, List<String> clusters) {
+    protected Message buildAggregateCluster(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, List<String> clusters) {
       ClusterConfig clusterConfig = ClusterConfig.newBuilder().addAllClusters(clusters).build();
       CustomClusterType type =
           CustomClusterType.newBuilder()
               .setName(ClientXdsClient.AGGREGATE_CLUSTER_TYPE_NAME)
               .setTypedConfig(Any.pack(clusterConfig))
               .build();
-      return Cluster.newBuilder()
+      Cluster.Builder builder = Cluster.newBuilder().setName(clusterName).setClusterType(type);
-          .setName(clusterName)
+      if (lbPolicy.equals("round_robin")) {
-          .setLbPolicy(LbPolicy.ROUND_ROBIN)
+        builder.setLbPolicy(LbPolicy.ROUND_ROBIN);
-          .setClusterType(type)
+      } else if (lbPolicy.equals("ring_hash")) {
-          .build();
+        builder.setLbPolicy(LbPolicy.RING_HASH);
+        builder.setRingHashLbConfig((RingHashLbConfig) ringHashLbConfig);
+      } else {
+        throw new AssertionError("Invalid LB policy");
+      }
+      return builder.build();
     }
 
-    private Cluster.Builder initClusterBuilder(String clusterName, boolean enableLrs,
+    private Cluster.Builder initClusterBuilder(String clusterName, String lbPolicy,
+        @Nullable Message ringHashLbConfig, boolean enableLrs,
         @Nullable Message upstreamTlsContext, @Nullable Message circuitBreakers) {
       Cluster.Builder builder = Cluster.newBuilder();
       builder.setName(clusterName);
-      builder.setLbPolicy(LbPolicy.ROUND_ROBIN);
+      if (lbPolicy.equals("round_robin")) {
+        builder.setLbPolicy(LbPolicy.ROUND_ROBIN);
+      } else if (lbPolicy.equals("ring_hash")) {
+        builder.setLbPolicy(LbPolicy.RING_HASH);
+        builder.setRingHashLbConfig((RingHashLbConfig) ringHashLbConfig);
+      } else {
+        throw new AssertionError("Invalid LB policy");
+      }
       if (enableLrs) {
         builder.setLrsServer(
             ConfigSource.newBuilder()
@@ -443,6 +461,22 @@ public class ClientXdsClientV3Test extends ClientXdsClientTestBase {
       return builder;
     }
 
+    @Override
+    protected Message buildRingHashLbConfig(String hashFunction, long minRingSize,
+        long maxRingSize) {
+      RingHashLbConfig.Builder builder = RingHashLbConfig.newBuilder();
+      if (hashFunction.equals("xx_hash")) {
+        builder.setHashFunction(HashFunction.XX_HASH);
+      } else if (hashFunction.equals("murmur_hash_2")) {
+        builder.setHashFunction(HashFunction.MURMUR_HASH_2);
+      } else {
+        throw new AssertionError("Invalid hash function");
+      }
+      builder.setMinimumRingSize(UInt64Value.newBuilder().setValue(minRingSize).build());
+      builder.setMaximumRingSize(UInt64Value.newBuilder().setValue(maxRingSize).build());
+      return builder.build();
+    }
+
     @Override
     protected Message buildUpstreamTlsContext(String secretName, String targetUri) {
       GrpcService grpcService =

xds/src/test/java/io/grpc/xds/XdsNameResolverTest.java

@@ -56,6 +56,7 @@ import io.grpc.xds.Matchers.PathMatcher;
 import io.grpc.xds.VirtualHost.Route;
 import io.grpc.xds.VirtualHost.Route.RouteAction;
 import io.grpc.xds.VirtualHost.Route.RouteAction.ClusterWeight;
+import io.grpc.xds.VirtualHost.Route.RouteAction.HashPolicy;
 import io.grpc.xds.VirtualHost.Route.RouteMatch;
 import io.grpc.xds.XdsClient.RdsResourceWatcher;
 import io.grpc.xds.XdsNameResolverProvider.XdsClientPoolFactory;
@@ -238,9 +239,11 @@ public class XdsNameResolverTest {
 
   private List<VirtualHost> buildUnmatchedVirtualHosts() {
     Route route1 = Route.create(RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-        RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null);
+        RouteAction.forCluster(
+            cluster2, Collections.<HashPolicy>emptyList(), TimeUnit.SECONDS.toNanos(15L)), null);
     Route route2 = Route.create(RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-        RouteAction.forCluster(cluster1, TimeUnit.SECONDS.toNanos(15L)), null);
+        RouteAction.forCluster(
+            cluster1, Collections.<HashPolicy>emptyList(), TimeUnit.SECONDS.toNanos(15L)), null);
     return Arrays.asList(
         VirtualHost.create("virtualhost-foo", Collections.singletonList("hello.googleapis.com"),
             Collections.singletonList(route1), null),
@@ -253,7 +256,8 @@ public class XdsNameResolverTest {
     resolver.start(mockListener);
     FakeXdsClient xdsClient = (FakeXdsClient) resolver.getXdsClient();
     Route route = Route.create(RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-        RouteAction.forCluster(cluster1, null), null);  // per-route timeout unset
+        RouteAction.forCluster(
+            cluster1, Collections.<HashPolicy>emptyList(), null), null); // per-route timeout unset
     VirtualHost virtualHost = VirtualHost.create("does not matter",
         Collections.singletonList(AUTHORITY), Collections.singletonList(route), null);
     xdsClient.deliverLdsUpdate(AUTHORITY, 0L, Collections.singletonList(virtualHost));
@@ -268,7 +272,8 @@ public class XdsNameResolverTest {
     resolver.start(mockListener);
     FakeXdsClient xdsClient = (FakeXdsClient) resolver.getXdsClient();
     Route route = Route.create(RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-        RouteAction.forCluster(cluster1, null), null);  // per-route timeout unset
+        RouteAction.forCluster(
+            cluster1, Collections.<HashPolicy>emptyList(), null), null); // per-route timeout unset
     VirtualHost virtualHost = VirtualHost.create("does not matter",
         Collections.singletonList(AUTHORITY), Collections.singletonList(route), null);
     xdsClient.deliverLdsUpdate(AUTHORITY, TimeUnit.SECONDS.toNanos(5L),
@@ -314,10 +319,14 @@ public class XdsNameResolverTest {
         Arrays.asList(
             Route.create(
                 RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-                RouteAction.forCluster("another-cluster", TimeUnit.SECONDS.toNanos(20L)), null),
+                RouteAction.forCluster(
+                    "another-cluster", Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(20L)), null),
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(
+                    cluster2, Collections.<HashPolicy>emptyList(), TimeUnit.SECONDS.toNanos(15L)),
+                null)));
     verify(mockListener).onResult(resolutionResultCaptor.capture());
     ResolutionResult result = resolutionResultCaptor.getValue();
     // Updated service config still contains cluster1 while it is removed resource. New calls no
@@ -349,10 +358,13 @@ public class XdsNameResolverTest {
         Arrays.asList(
             Route.create(
                 RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-                RouteAction.forCluster("another-cluster", TimeUnit.SECONDS.toNanos(20L)), null),
+                RouteAction.forCluster(
+                    "another-cluster", Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(20L)), null),
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(cluster2, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null)));
     // Two consecutive service config updates: one for removing clcuster1,
     // one for adding "another=cluster".
     verify(mockListener, times(2)).onResult(resolutionResultCaptor.capture());
@@ -380,10 +392,12 @@ public class XdsNameResolverTest {
         Arrays.asList(
             Route.create(
                 RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-                RouteAction.forCluster("another-cluster", TimeUnit.SECONDS.toNanos(20L)), null),
+                RouteAction.forCluster("another-cluster", Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(20L)), null),
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(cluster2, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null)));
 
     verify(mockListener).onResult(resolutionResultCaptor.capture());
     ResolutionResult result = resolutionResultCaptor.getValue();
@@ -396,10 +410,12 @@ public class XdsNameResolverTest {
         Arrays.asList(
             Route.create(
                 RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-                RouteAction.forCluster("another-cluster", TimeUnit.SECONDS.toNanos(15L)), null),
+                RouteAction.forCluster("another-cluster", Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null),
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(cluster2, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null)));
     verifyNoMoreInteractions(mockListener);  // no cluster added/deleted
     assertCallSelectResult(call1, configSelector, "another-cluster", 15.0);
   }
@@ -414,16 +430,19 @@ public class XdsNameResolverTest {
         Collections.singletonList(
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(cluster2, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null)));
     xdsClient.deliverLdsUpdate(
         AUTHORITY,
         Arrays.asList(
             Route.create(
                 RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster1, TimeUnit.SECONDS.toNanos(15L)), null),
+                RouteAction.forCluster(cluster1, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null),
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(cluster2, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null)));
     testCall.deliverErrorStatus();
     verifyNoMoreInteractions(mockListener);
   }
@@ -443,6 +462,7 @@ public class XdsNameResolverTest {
                     Arrays.asList(
                         ClusterWeight.create(cluster1, 20, null),
                         ClusterWeight.create(cluster2, 80, null)),
+                    Collections.<HashPolicy>emptyList(),
                     TimeUnit.SECONDS.toNanos(20L)), null)));
     verify(mockListener).onResult(resolutionResultCaptor.capture());
     ResolutionResult result = resolutionResultCaptor.getValue();
@@ -500,10 +520,12 @@ public class XdsNameResolverTest {
         Arrays.asList(
             Route.create(
                 RouteMatch.withPathExactOnly(call1.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster1, TimeUnit.SECONDS.toNanos(15L)), null),
+                RouteAction.forCluster(cluster1, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null),
             Route.create(
                 RouteMatch.withPathExactOnly(call2.getFullMethodNameForPath()),
-                RouteAction.forCluster(cluster2, TimeUnit.SECONDS.toNanos(15L)), null)));
+                RouteAction.forCluster(cluster2, Collections.<HashPolicy>emptyList(),
+                    TimeUnit.SECONDS.toNanos(15L)), null)));
     verify(mockListener).onResult(resolutionResultCaptor.capture());
     ResolutionResult result = resolutionResultCaptor.getValue();
     assertThat(result.getAddresses()).isEmpty();