added ShardRegionProxy support to cluster hosting

src/Akka.Cluster.Hosting/AkkaClusterHostingExtensions.cs

@@ -164,5 +164,58 @@ public static AkkaConfigurationBuilder WithShardRegion<TKey>(this AkkaConfigurat
                 registry.TryRegister<TKey>(shardRegion);
             });
         }
+
+        /// <summary>
+        /// Starts a ShardRegionProxy that points to a <see cref="ShardRegion"/> hosted on a different role inside the cluster
+        /// and registers the <see cref="IActorRef"/> with <see cref="TKey"/> in the
+        /// <see cref="ActorRegistry"/> for this <see cref="ActorSystem"/>. 
+        /// </summary>
+        /// <param name="builder">The builder instance being configured.</param>
+        /// <param name="typeName">The name of the entity type</param>
+        /// <param name="roleName">The role of the Akka.Cluster member that is hosting this <see cref="ShardRegion"/>.</param>
+        /// <param name="extractEntityId">
+        /// Partial function to extract the entity id and the message to send to the entity from the incoming message,
+        /// if the partial function does not match the message will be `unhandled`,
+        /// i.e.posted as `Unhandled` messages on the event stream
+        /// </param>
+        /// <param name="extractShardId">
+        /// Function to determine the shard id for an incoming message, only messages that passed the `extractEntityId` will be used
+        /// </param>
+        /// <typeparam name="TKey">The type key to use to retrieve the <see cref="IActorRef"/> for this <see cref="ShardRegion"/>.</typeparam>
+        /// <returns>The same <see cref="AkkaConfigurationBuilder"/> instance originally passed in.</returns>
+        public static AkkaConfigurationBuilder WithShardRegionProxy<TKey>(this AkkaConfigurationBuilder builder,
+            string typeName, string roleName, ExtractEntityId extractEntityId, ExtractShardId extractShardId)
+        {
+            return builder.WithActors(async (system, registry) =>
+            {
+                var shardRegionProxy = await ClusterSharding.Get(system)
+                    .StartProxyAsync(typeName, roleName, extractEntityId, extractShardId);
+                registry.TryRegister<TKey>(shardRegionProxy);
+            });
+        }
+
+        /// <summary>
+        /// Starts a ShardRegionProxy that points to a <see cref="ShardRegion"/> hosted on a different role inside the cluster
+        /// and registers the <see cref="IActorRef"/> with <see cref="TKey"/> in the
+        /// <see cref="ActorRegistry"/> for this <see cref="ActorSystem"/>. 
+        /// </summary>
+        /// <param name="builder">The builder instance being configured.</param>
+        /// <param name="typeName">The name of the entity type</param>
+        /// <param name="roleName">The role of the Akka.Cluster member that is hosting this <see cref="ShardRegion"/>.</param>
+        /// <param name="messageExtractor">
+        /// Functions to extract the entity id, shard id, and the message to send to the entity from the incoming message.
+        /// </param>
+        /// <typeparam name="TKey">The type key to use to retrieve the <see cref="IActorRef"/> for this <see cref="ShardRegion"/>.</typeparam>
+        /// <returns>The same <see cref="AkkaConfigurationBuilder"/> instance originally passed in.</returns>
+        public static AkkaConfigurationBuilder WithShardRegionProxy<TKey>(this AkkaConfigurationBuilder builder,
+            string typeName, string roleName, IMessageExtractor messageExtractor)
+        {
+            return builder.WithActors(async (system, registry) =>
+            {
+                var shardRegionProxy = await ClusterSharding.Get(system)
+                    .StartProxyAsync(typeName, roleName, messageExtractor);
+                registry.TryRegister<TKey>(shardRegionProxy);
+            });
+        }
     }
 }