Google Pub/Sub: Configurable host (for ordering)

google-cloud-pub-sub/src/main/scala/akka/stream/alpakka/googlecloud/pubsub/impl/PubSubApi.scala

@@ -220,18 +220,20 @@ private[pubsub] trait PubSubApi {
       }
     }.withDefaultRetry
 
-  private def pool[T: FromResponseUnmarshaller, Ctx](parallelism: Int)(
+  private def pool[T: FromResponseUnmarshaller, Ctx](parallelism: Int, host: Option[String])(
       implicit system: ActorSystem
   ): FlowWithContext[HttpRequest, Ctx, Try[T], Ctx, Future[HostConnectionPool]] =
     GoogleHttp().cachedHostConnectionPoolWithContext[T, Ctx](
-      PubSubGoogleApisHost,
+      host.getOrElse(PubSubGoogleApisHost),
       PubSubGoogleApisPort,
       https = !isEmulated,
       authenticate = !isEmulated,
       parallelism = parallelism
     )
 
-  def publish[T](topic: String, parallelism: Int): FlowWithContext[PublishRequest, T, PublishResponse, T, NotUsed] =
+  def publish[T](topic: String,
+                 parallelism: Int,
+                 host: Option[String]): FlowWithContext[PublishRequest, T, PublishResponse, T, NotUsed] =
     FlowWithContext.fromTuples {
       Flow
         .fromMaterializer { (mat, attr) =>
@@ -247,13 +249,16 @@ private[pubsub] trait PubSubApi {
                   HttpRequest(POST, url, entity = entity)
                 }(ExecutionContexts.parasitic)
             }
-            .via(pool[PublishResponse, T](parallelism))
+            .via(pool[PublishResponse, T](parallelism, host))
             .map(_.get)
             .asFlow
         }
         .mapMaterializedValue(_ => NotUsed)
     }
 
+  def publish[T](topic: String, parallelism: Int): FlowWithContext[PublishRequest, T, PublishResponse, T, NotUsed] =
+    publish(topic, parallelism, None)
+
   private implicit val publishResponseUnmarshaller: FromResponseUnmarshaller[PublishResponse] =
     Unmarshaller.withMaterializer { implicit ec => implicit mat => response: HttpResponse =>
       response.status match {

google-cloud-pub-sub/src/main/scala/akka/stream/alpakka/googlecloud/pubsub/javadsl/GooglePubSub.scala

@@ -5,7 +5,6 @@
 package akka.stream.alpakka.googlecloud.pubsub.javadsl
 
 import java.util.concurrent.CompletionStage
-
 import akka.actor.Cancellable
 import akka.stream.alpakka.googlecloud.pubsub.scaladsl.{GooglePubSub => GPubSub}
 import akka.stream.alpakka.googlecloud.pubsub.{AcknowledgeRequest, PubSubConfig, PublishRequest, ReceivedMessage}
@@ -14,6 +13,7 @@ import akka.{Done, NotUsed}
 
 import scala.jdk.CollectionConverters._
 import scala.compat.java8.FutureConverters._
+import scala.compat.java8.OptionConverters.RichOptionalGeneric
 import scala.concurrent.Future
 
 /**
@@ -23,15 +23,27 @@ object GooglePubSub {
 
   /**
    * Creates a flow to that publishes messages to a topic and emits the message ids.
+   * @param overrideHost if present publish message will be sent to specific host,
+   *                     can be used to send message to specific regional endpoint,
+   *                     which can be important when ordering is enabled
    */
   def publish(topic: String,
               config: PubSubConfig,
+              overrideHost: java.util.Optional[String],
               parallelism: Int): Flow[PublishRequest, java.util.List[String], NotUsed] =
     GPubSub
-      .publish(topic, config, parallelism)
+      .publish(topic, config, overrideHost.asScala, parallelism)
       .map(response => response.asJava)
       .asJava
 
+  /**
+   * Creates a flow to that publishes messages to a topic and emits the message ids.
+   */
+  def publish(topic: String,
+              config: PubSubConfig,
+              parallelism: Int): Flow[PublishRequest, java.util.List[String], NotUsed] =
+    publish(topic, config, java.util.Optional.empty(), parallelism)
+
   /**
    * Creates a flow to that publishes messages to a topic and emits the message ids and carries a context
    * through.

google-cloud-pub-sub/src/main/scala/akka/stream/alpakka/googlecloud/pubsub/scaladsl/GooglePubSub.scala

@@ -29,29 +29,83 @@ protected[pubsub] trait GooglePubSub {
 
   /**
    * Creates a flow to that publishes messages to a topic and emits the message ids.
+   * @param overrideHost if present publish message will be sent to specific host,
+   *                     can be used to send message to specific regional endpoint,
+   *                     which can be important when ordering is enabled
    */
   def publish(topic: String,
               config: PubSubConfig,
-              parallelism: Int = 1): Flow[PublishRequest, immutable.Seq[String], NotUsed] =
+              overrideHost: Option[String],
+              parallelism: Int): Flow[PublishRequest, immutable.Seq[String], NotUsed] =
     Flow[PublishRequest]
       .map((_, ()))
       .via(
-        publishWithContext[Unit](topic, config, parallelism).asFlow
+        publishWithContext[Unit](topic, config, overrideHost, parallelism).asFlow
       )
       .map(_._1)
 
+  /**
+   * Creates a flow to that publishes messages to a topic and emits the message ids.
+   * @param overrideHost if present publish message will be sent to specific host,
+   *                     can be used to send message to specific regional endpoint,
+   *                     which can be important when ordering is enabled
+   */
+  def publish(topic: String,
+              config: PubSubConfig,
+              overrideHost: Option[String]): Flow[PublishRequest, immutable.Seq[String], NotUsed] =
+    publish(topic, config, overrideHost, parallelism = 1)
+
+  /**
+   * Creates a flow to that publishes messages to a topic and emits the message ids.
+   */
+  def publish(topic: String,
+              config: PubSubConfig,
+              parallelism: Int = 1): Flow[PublishRequest, immutable.Seq[String], NotUsed] =
+    publish(topic, config, None, parallelism)
+
   /**
    * Creates a flow to that publishes messages to a topic and emits the message ids and carries a context
    * through.
+   * @param overrideHost if present publish message will be sent to specific host,
+   *                     can be used to send message to specific regional endpoint,
+   *                     which can be important when ordering is enabled
    */
   def publishWithContext[C](
       topic: String,
       config: PubSubConfig,
-      parallelism: Int = 1
+      overrideHost: Option[String],
+      parallelism: Int
   ): FlowWithContext[PublishRequest, C, immutable.Seq[String], C, NotUsed] =
     // some wrapping back and forth as FlowWithContext doesn't offer `setup`
     // https://github.com/akka/akka/issues/27883
-    FlowWithContext.fromTuples(flow(config)(httpApi.publish[C](topic, parallelism).asFlow)).map(_.messageIds)
+    FlowWithContext
+      .fromTuples(flow(config)(httpApi.publish[C](topic, parallelism, overrideHost).asFlow))
+      .map(_.messageIds)
+
+  /**
+   * Creates a flow to that publishes messages to a topic and emits the message ids and carries a context
+   * through.
+   * @param overrideHost if present publish message will be sent to specific host,
+   *                     can be used to send message to specific regional endpoint,
+   *                     which can be important when ordering is enabled
+   */
+  def publishWithContext[C](
+      topic: String,
+      config: PubSubConfig,
+      overrideHost: Option[String]
+  ): FlowWithContext[PublishRequest, C, immutable.Seq[String], C, NotUsed] =
+    publishWithContext(topic, config, overrideHost, parallelism = 1)
+
+  /**
+   * Creates a flow to that publishes messages to a topic and emits the message ids and carries a context
+   * through.
+   */
+  def publishWithContext[C](
+      topic: String,
+      config: PubSubConfig,
+      parallelism: Int = 1
+  ): FlowWithContext[PublishRequest, C, immutable.Seq[String], C, NotUsed] =
+    publishWithContext(topic, config, None, parallelism)
 
   /**
    * Creates a source pulling messages from a subscription.

google-cloud-pub-sub/src/test/java/docs/javadsl/ExampleUsageJava.java

@@ -76,6 +76,10 @@ private static void example() throws NoSuchAlgorithmException, InvalidKeySpecExc
     // #publish-fast
 
     // #publish with ordering key
+    // to provide ordering messages must be sent to the same regional endpoint
+    Flow<PublishRequest, List<String>, NotUsed> publishToRegionalEndpointFlow =
+        GooglePubSub.publish(topic, config, Optional.of("europe-west1-pubsub.googleapis.com"), 1);
+
     PublishMessage publishMessageWithOrderingKey =
         PublishMessage.create(
             new String(Base64.getEncoder().encode("Hello Google!".getBytes())),
@@ -85,7 +89,7 @@ private static void example() throws NoSuchAlgorithmException, InvalidKeySpecExc
         PublishRequest.create(Lists.newArrayList(publishMessage));
 
     CompletionStage<List<List<String>>> publishedMessageWithOrderingKeyIds =
-        source.via(publishFlow).runWith(Sink.seq(), system);
+        source.via(publishToRegionalEndpointFlow).runWith(Sink.seq(), system);
     // #publish with ordering key
 
     // #subscribe

google-cloud-pub-sub/src/test/scala/akka/stream/alpakka/googlecloud/pubsub/impl/PubSubApiSpec.scala

@@ -160,6 +160,45 @@ class PubSubApiSpec extends AnyFlatSpec with BeforeAndAfterAll with ScalaFutures
     result.futureValue._2 shouldBe (())
   }
 
+  it should "publish to overridden host" in {
+    val httpApiWithHostToOverride = new PubSubApi {
+      val isEmulated = false
+      val PubSubGoogleApisHost = "invalid-host" //this host must be override to complete the test
+      val PubSubGoogleApisPort = wiremockServer.httpsPort()
+    }
+
+    val publishMessage =
+      PublishMessage(
+        data = new String(Base64.getEncoder.encode("Hello Google!".getBytes))
+      )
+
+    val publishRequest = PublishRequest(Seq(publishMessage))
+
+    val expectedPublishRequest =
+      """{"messages":[{"data":"SGVsbG8gR29vZ2xlIQ=="}]}"""
+    val publishResponse = """{"messageIds":["1"]}"""
+
+    mock.register(
+      WireMock
+        .post(
+          urlEqualTo(s"/v1/projects/${TestCredentials.projectId}/topics/topic1:publish?prettyPrint=false")
+        )
+        .withRequestBody(WireMock.equalToJson(expectedPublishRequest))
+        .withHeader("Authorization", WireMock.equalTo("Bearer " + accessToken))
+        .willReturn(
+          aResponse()
+            .withStatus(200)
+            .withBody(publishResponse)
+            .withHeader("Content-Type", "application/json")
+        )
+    )
+    val flow = httpApiWithHostToOverride.publish[Unit]("topic1", 1, Some("localhost"))
+    val result =
+      Source.single((publishRequest, ())).via(flow).toMat(Sink.head)(Keep.right).run()
+    result.futureValue._1.messageIds shouldBe Seq("1")
+    result.futureValue._2 shouldBe (())
+  }
+
   it should "publish without Authorization header to emulator" in {
 
     val publishMessage =

google-cloud-pub-sub/src/test/scala/docs/scaladsl/ExampleUsage.scala

@@ -67,11 +67,13 @@ class ExampleUsage {
   //#publish-fast
 
   //#publish with ordering key
-  val messageWithOrderingKey =
+  val publishToRegionalEndpointFlow: Flow[PublishRequest, Seq[String], NotUsed] =
+    GooglePubSub.publish(topic, config, Some("europe-west1-pubsub.googleapis.com"))
+  val messageWithOrderingKey: PublishMessage =
     PublishMessage(new String(Base64.getEncoder.encode("Hello Google!".getBytes)), None, Some("my-ordering-key"))
   val publishedMessageWithOrderingKeyIds: Future[Seq[Seq[String]]] = Source
     .single(PublishRequest(Seq(messageWithOrderingKey)))
-    .via(publishFlow)
+    .via(publishToRegionalEndpointFlow)
     .runWith(Sink.seq)
   //#publish with ordering key