feat(storage): add support for DirectPath over Interconnect

java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/GrpcStorageOptions.java

@@ -134,6 +134,9 @@ public final class GrpcStorageOptions extends StorageOptions
   private static final String GCS_SCOPE = "https://www.googleapis.com/auth/devstorage.full_control";
   private static final Set<String> SCOPES = ImmutableSet.of(GCS_SCOPE);
   private static final String DEFAULT_HOST = "https://storage.googleapis.com";
+  private static final String DEFAULT_HOST_DIRECT_PATH = "https://storage-direct.googleapis.com";
+  private static final String DEFAULT_HOST_NO_SCHEME = "storage.googleapis.com";
+  private static final String DEFAULT_HOST_DIRECT_PATH_NO_SCHEME = "storage-direct.googleapis.com";
   // If true, disable the bound-token-by-default feature for DirectPath.
   private static final boolean DIRECT_PATH_BOUND_TOKEN_DISABLED =
       Boolean.parseBoolean(
@@ -142,6 +145,7 @@ public final class GrpcStorageOptions extends StorageOptions
   private final GrpcRetryAlgorithmManager retryAlgorithmManager;
   private final java.time.Duration terminationAwaitDuration;
   private final boolean attemptDirectPath;
+  private final boolean attemptDirectPathXdsOverInterconnect;
   private final boolean enableGrpcClientMetrics;
 
   private final boolean grpcClientMetricsManuallyEnabled;
@@ -160,6 +164,7 @@ private GrpcStorageOptions(Builder builder, GrpcStorageDefaults serviceDefaults)
             builder.terminationAwaitDuration,
             serviceDefaults.getTerminationAwaitDurationJavaTime());
     this.attemptDirectPath = builder.attemptDirectPath;
+    this.attemptDirectPathXdsOverInterconnect = builder.attemptDirectPathXdsOverInterconnect;
     this.enableGrpcClientMetrics = builder.enableGrpcClientMetrics;
     this.grpcClientMetricsManuallyEnabled = builder.grpcMetricsManuallyEnabled;
     this.grpcInterceptorProvider = builder.grpcInterceptorProvider;
@@ -197,6 +202,23 @@ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundE
     this.openTelemetry = HttpStorageOptions.getDefaultInstance().getOpenTelemetry();
   }
 
+  private static String rewriteHost(String endpoint, String oldHost, String newHost) {
+    String prefix = "";
+    String rest = endpoint;
+    int schemeIndex = endpoint.indexOf("://");
+    if (schemeIndex >= 0) {
+      prefix = endpoint.substring(0, schemeIndex + 3);
+      rest = endpoint.substring(schemeIndex + 3);
+    }
+    if (rest.startsWith(oldHost)) {
+      int len = oldHost.length();
+      if (rest.length() == len || rest.charAt(len) == ':' || rest.charAt(len) == '/') {
+        return prefix + newHost + rest.substring(len);
+      }
+    }
+    return endpoint;
+  }
+
   /**
    * We have to perform several introspections and detections to cross-wire/support several features
    * that are either gapic primitives, ServiceOption primitives or GCS semantic requirements.
@@ -230,6 +252,9 @@ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundE
    */
   private Tuple<StorageSettings, Opts<UserProject>> resolveSettingsAndOpts() throws IOException {
     String endpoint = getHost();
+    if (attemptDirectPathXdsOverInterconnect) {
+      endpoint = rewriteHost(endpoint, "storage.googleapis.com", "storage-direct.googleapis.com");
+    }
     URI uri = URI.create(endpoint);
     String scheme = uri.getScheme();
     int port = uri.getPort();
@@ -322,7 +347,8 @@ private Tuple<StorageSettings, Opts<UserProject>> resolveSettingsAndOpts() throw
         InstantiatingGrpcChannelProvider.newBuilder()
             .setEndpoint(endpoint)
             .setAllowNonDefaultServiceAccount(true)
-            .setAttemptDirectPath(attemptDirectPath);
+            .setAttemptDirectPath(attemptDirectPath || attemptDirectPathXdsOverInterconnect)
+            .setAttemptDirectPathXdsOverInterconnect(attemptDirectPathXdsOverInterconnect);
 
     if (!DIRECT_PATH_BOUND_TOKEN_DISABLED) {
       channelProviderBuilder.setAllowHardBoundTokenTypes(
@@ -337,6 +363,18 @@ private Tuple<StorageSettings, Opts<UserProject>> resolveSettingsAndOpts() throw
       channelProviderBuilder.setAttemptDirectPathXds();
     }
 
+    if (attemptDirectPathXdsOverInterconnect) {
+      com.google.api.core.ApiFunction<ManagedChannelBuilder, ManagedChannelBuilder>
+          existingConfigurator = channelProviderBuilder.getChannelConfigurator();
+      channelProviderBuilder.setChannelConfigurator(
+          channelBuilder -> {
+            if (existingConfigurator != null) {
+              channelBuilder = existingConfigurator.apply(channelBuilder);
+            }
+            return channelBuilder.overrideAuthority("storage.googleapis.com");
+          });
+    }
+
     if (scheme.equals("http")) {
       channelProviderBuilder.setChannelConfigurator(ManagedChannelBuilder::usePlaintext);
     }
@@ -428,6 +466,7 @@ public int hashCode() {
         retryAlgorithmManager,
         terminationAwaitDuration,
         attemptDirectPath,
+        attemptDirectPathXdsOverInterconnect,
         enableGrpcClientMetrics,
         grpcInterceptorProvider,
         blobWriteSessionConfig,
@@ -445,6 +484,7 @@ public boolean equals(Object o) {
     }
     GrpcStorageOptions that = (GrpcStorageOptions) o;
     return attemptDirectPath == that.attemptDirectPath
+        && attemptDirectPathXdsOverInterconnect == that.attemptDirectPathXdsOverInterconnect
         && enableGrpcClientMetrics == that.enableGrpcClientMetrics
         && Objects.equals(retryAlgorithmManager, that.retryAlgorithmManager)
         && Objects.equals(terminationAwaitDuration, that.terminationAwaitDuration)
@@ -494,6 +534,7 @@ public static final class Builder extends StorageOptions.Builder {
     private StorageRetryStrategy storageRetryStrategy;
     private java.time.Duration terminationAwaitDuration;
     private boolean attemptDirectPath = GrpcStorageDefaults.INSTANCE.isAttemptDirectPath();
+    private boolean attemptDirectPathXdsOverInterconnect = false;
     private boolean enableGrpcClientMetrics =
         GrpcStorageDefaults.INSTANCE.isEnableGrpcClientMetrics();
     private GrpcInterceptorProvider grpcInterceptorProvider =
@@ -512,6 +553,7 @@ public static final class Builder extends StorageOptions.Builder {
       this.storageRetryStrategy = gso.getRetryAlgorithmManager().retryStrategy;
       this.terminationAwaitDuration = gso.getTerminationAwaitDuration();
       this.attemptDirectPath = gso.attemptDirectPath;
+      this.attemptDirectPathXdsOverInterconnect = gso.attemptDirectPathXdsOverInterconnect;
       this.enableGrpcClientMetrics = gso.enableGrpcClientMetrics;
       this.grpcInterceptorProvider = gso.grpcInterceptorProvider;
       this.blobWriteSessionConfig = gso.blobWriteSessionConfig;
@@ -556,6 +598,18 @@ public GrpcStorageOptions.Builder setAttemptDirectPath(boolean attemptDirectPath
       return this;
     }
 
+    /**
+     * Option for whether this client should attempt to use DirectPath over Interconnect (on-premise
+     * xDS name resolution).
+     *
+     * @since 2.45.0
+     */
+    public GrpcStorageOptions.Builder setAttemptDirectPathXdsOverInterconnect(
+        boolean attemptDirectPathXdsOverInterconnect) {
+      this.attemptDirectPathXdsOverInterconnect = attemptDirectPathXdsOverInterconnect;
+      return this;
+    }
+
     /**
      * Option for whether this client should emit internal gRPC client internal metrics to Cloud
      * Monitoring. To disable metric reporting, set this to false. True by default. Emitting metrics

java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageOptionsBuilderTest.java

@@ -69,6 +69,37 @@ public void grpc() throws Exception {
         () -> assertThat(rebuilt.hashCode()).isEqualTo(base.hashCode()));
   }
 
+  @Test
+  public void grpc_attemptDirectPathXdsOverInterconnect() throws Exception {
+    com.google.auth.Credentials mockCreds = com.google.cloud.NoCredentials.getInstance();
+    GrpcStorageOptions options =
+        GrpcStorageOptions.grpc()
+            .setCredentials(mockCreds)
+            .setAttemptDirectPathXdsOverInterconnect(true)
+            .build();
+
+    GrpcStorageOptions rebuilt = options.toBuilder().build();
+    assertAll(
+        () -> assertThat(rebuilt).isEqualTo(options),
+        () -> assertThat(rebuilt.hashCode()).isEqualTo(options.hashCode()));
+
+    com.google.storage.v2.StorageSettings settings = options.getStorageSettings();
+    assertThat(settings.getEndpoint()).isEqualTo("storage-direct.googleapis.com:443");
+
+    com.google.api.gax.rpc.TransportChannelProvider tcp = settings.getTransportChannelProvider();
+    assertThat(tcp).isInstanceOf(com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.class);
+    com.google.api.gax.grpc.InstantiatingGrpcChannelProvider provider =
+        (com.google.api.gax.grpc.InstantiatingGrpcChannelProvider) tcp;
+
+    // Verify attemptDirectPathXdsOverInterconnect is set to true on the provider using reflection
+    java.lang.reflect.Field field =
+        com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.class.getDeclaredField(
+            "attemptDirectPathXdsOverInterconnect");
+    field.setAccessible(true);
+    Boolean value = (Boolean) field.get(provider);
+    assertThat(value).isTrue();
+  }
+
   @Test
   public void useJwtAccessWithScope_defaultsToFalse() {
     HttpStorageOptions httpOptions = HttpStorageOptions.http().build();

java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITGrpcDirectPathTest.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.cloud.storage.it;
+
+import static org.junit.Assume.assumeTrue;
+
+import com.google.cloud.storage.Storage;
+import com.google.cloud.storage.StorageOptions;
+import com.google.cloud.storage.TransportCompatibility.Transport;
+import com.google.cloud.storage.it.runner.StorageITRunner;
+import com.google.cloud.storage.it.runner.annotations.Backend;
+import com.google.cloud.storage.it.runner.annotations.Inject;
+import com.google.cloud.storage.it.runner.annotations.SingleBackend;
+import com.google.cloud.storage.it.runner.annotations.StorageFixture;
+import org.junit.Ignore;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(StorageITRunner.class)
+@SingleBackend(Backend.PROD)
+public final class ITGrpcDirectPathTest {
+
+  @Inject
+  @StorageFixture(Transport.GRPC)
+  public Storage storage;
+
+  @Ignore(
+      "Bypassed because DirectPath over Interconnect (GCI) requires a specialized hybrid network environment (Interconnect and Traffic Director configured for storage-direct) and cannot be validated in standard CI or local workstations.")
+  @Test
+  public void clientShouldWork_directPathXdsOverInterconnect() throws Exception {
+    assumeTrue(
+        "Environment cannot resolve storage-direct.googleapis.com", canResolveDirectPathAddress());
+    StorageOptions options =
+        StorageOptions.grpc()
+            .setCredentials(storage.getOptions().getCredentials())
+            .setAttemptDirectPathXdsOverInterconnect(true)
+            .setEnableGrpcClientMetrics(false)
+            .build();
+    try (Storage client = options.getService()) {
+      client.list(Storage.BucketListOption.pageSize(1));
+    }
+  }
+
+  private static boolean canResolveDirectPathAddress() {
+    try {
+      java.net.InetAddress.getAllByName("storage-direct.googleapis.com");
+      return true;
+    } catch (java.net.UnknownHostException e) {
+      return false;
+    }
+  }
+}

java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITStorageOptionsTest.java

@@ -84,6 +84,17 @@ public void clientShouldConstructCleanly_directPath() throws Exception {
     doTest(options);
   }
 
+  @Test
+  public void clientShouldConstructCleanly_directPathXdsOverInterconnect() throws Exception {
+    StorageOptions options =
+        StorageOptions.grpc()
+            .setCredentials(credentials)
+            .setAttemptDirectPathXdsOverInterconnect(true)
+            .setEnableGrpcClientMetrics(false)
+            .build();
+    doTest(options);
+  }
+
   @Test
   public void lackOfProjectIdDoesNotPreventConstruction_http() throws Exception {
     StorageOptions options = StorageOptions.http().setCredentials(credentials).build();