chore(auth): Address remaining Regional Access Boundary feedback

google-auth-library-java/oauth2_http/java/com/google/auth/oauth2/RegionalAccessBoundary.java

@@ -40,10 +40,11 @@
 import com.google.api.client.http.HttpResponse;
 import com.google.api.client.http.HttpUnsuccessfulResponseHandler;
 import com.google.api.client.json.GenericJson;
-import com.google.api.client.json.JsonParser;
+import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.Clock;
 import com.google.api.client.util.ExponentialBackOff;
 import com.google.api.client.util.Key;
+import com.google.api.core.InternalApi;
 import com.google.auth.http.HttpTransportFactory;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.MoreObjects;
@@ -53,7 +54,6 @@
 import java.io.Serializable;
 import java.util.Collections;
 import java.util.List;
-import javax.annotation.Nullable;
 
 /**
  * Represents the regional access boundary configuration for a credential. This class holds the
@@ -67,10 +67,24 @@ final class RegionalAccessBoundary implements Serializable {
   static final String X_ALLOWED_LOCATIONS_HEADER_KEY = "x-allowed-locations";
   private static final long serialVersionUID = -2428522338274020302L;
 
-  // Note: this is for internal testing use use only.
-  // TODO: Fix unit test mocks so this can be removed
-  // Refer -> https://github.com/googleapis/google-auth-library-java/issues/1898
-  static final String ENABLE_EXPERIMENT_ENV_VAR = "GOOGLE_AUTH_TRUST_BOUNDARY_ENABLE_EXPERIMENT";
+  private static final ThreadLocal<Boolean> DISABLE_RAB_FOR_TESTS =
+      ThreadLocal.withInitial(() -> false);
+
+  @VisibleForTesting
+  static void disableForTests() {
+    DISABLE_RAB_FOR_TESTS.set(true);
+  }
+
+  @VisibleForTesting
+  static void enableForTests() {
+    DISABLE_RAB_FOR_TESTS.set(false);
+  }
+
+  @VisibleForTesting
+  static void resetForTests() {
+    DISABLE_RAB_FOR_TESTS.remove();
+  }
+
   static final long TTL_MILLIS = 6 * 60 * 60 * 1000L; // 6 hours
   static final long REFRESH_THRESHOLD_MILLIS = 1 * 60 * 60 * 1000L; // 1 hour
 
@@ -79,8 +93,6 @@ final class RegionalAccessBoundary implements Serializable {
   private final long refreshTime;
   private transient Clock clock;
 
-  private static EnvironmentProvider environmentProvider = SystemEnvironmentProvider.getInstance();
-
   /**
    * Creates a new RegionalAccessBoundary instance.
    *
@@ -172,28 +184,16 @@ public String toString() {
     }
   }
 
-  @VisibleForTesting
-  static void setEnvironmentProviderForTest(@Nullable EnvironmentProvider provider) {
-    environmentProvider = provider == null ? SystemEnvironmentProvider.getInstance() : provider;
-  }
-
   /**
-   * Checks if the regional access boundary feature is enabled. The feature is enabled if the
-   * environment variable or system property "GOOGLE_AUTH_TRUST_BOUNDARY_ENABLE_EXPERIMENT" is set
-   * to "true" or "1" (case-insensitive).
+   * Checks if the regional access boundary feature is enabled.
+   *
+   * <p>This method is for internal use only and may be changed or removed in future releases.
    *
    * @return True if the regional access boundary feature is enabled, false otherwise.
    */
+  @InternalApi
   static boolean isEnabled() {
-    String enabled = environmentProvider.getEnv(ENABLE_EXPERIMENT_ENV_VAR);
-    if (enabled == null) {
-      enabled = System.getProperty(ENABLE_EXPERIMENT_ENV_VAR);
-    }
-    if (enabled == null) {
-      return false;
-    }
-    String lowercased = enabled.toLowerCase();
-    return "true".equals(lowercased) || "1".equals(enabled);
+    return !DISABLE_RAB_FOR_TESTS.get();
   }
 
   /**
@@ -249,15 +249,20 @@ static RegionalAccessBoundary refresh(
     HttpIOExceptionHandler ioExceptionHandler = new HttpBackOffIOExceptionHandler(backoff);
     request.setIOExceptionHandler(ioExceptionHandler);
 
+    request.setParser(new JsonObjectParser(OAuth2Utils.JSON_FACTORY));
+
     RegionalAccessBoundaryResponse json;
+    HttpResponse response = null;
     try {
-      HttpResponse response = request.execute();
-      String responseString = response.parseAsString();
-      JsonParser parser = OAuth2Utils.JSON_FACTORY.createJsonParser(responseString);
-      json = parser.parseAndClose(RegionalAccessBoundaryResponse.class);
+      response = request.execute();
+      json = response.parseAs(RegionalAccessBoundaryResponse.class);
     } catch (IOException e) {
       throw new IOException(
           "RegionalAccessBoundary: Failure while getting regional access boundaries:", e);
+    } finally {
+      if (response != null) {
+        response.disconnect();
+      }
     }
     String encodedLocations = json.getEncodedLocations();
     // The encodedLocations is the value attached to the x-allowed-locations header, and

google-auth-library-java/oauth2_http/java/com/google/auth/oauth2/RegionalAccessBoundaryManager.java

@@ -36,6 +36,9 @@
 import com.google.auth.http.HttpTransportFactory;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.util.concurrent.SettableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Level;
 import javax.annotation.Nullable;
@@ -78,6 +81,20 @@ final class RegionalAccessBoundaryManager {
   private final AtomicReference<CooldownState> cooldownState =
       new AtomicReference<>(new CooldownState(0, INITIAL_COOLDOWN_MILLIS));
 
+  // Unbounded thread creation is discouraged in library code to avoid resource
+  // exhaustion. A shared, bounded executor service ensures a hard limit (5)
+  // on concurrent refresh tasks, while threadCount provides unique names
+  // for easier debugging.
+  private static final AtomicInteger threadCount = new AtomicInteger(0);
+  private static final ExecutorService EXECUTOR =
+      Executors.newFixedThreadPool(
+          5,
+          r -> {
+            Thread t = new Thread(r, "RAB-refresh-" + threadCount.getAndIncrement());
+            t.setDaemon(true);
+            return t;
+          });
+
   private final transient Clock clock;
   private final int maxRetryElapsedTimeMillis;
 
@@ -161,14 +178,7 @@ void triggerAsyncRefresh(
           };
 
       try {
-        // We use new Thread() here instead of
-        // CompletableFuture.runAsync() (which uses ForkJoinPool.commonPool()).
-        // This avoids consuming CPU resources since
-        // The common pool has a small, fixed number of threads designed for
-        // CPU-bound tasks.
-        Thread refreshThread = new Thread(refreshTask, "RAB-refresh-thread");
-        refreshThread.setDaemon(true);
-        refreshThread.start();
+        EXECUTOR.submit(refreshTask);
       } catch (Exception | Error e) {
         // If scheduling fails (e.g., RejectedExecutionException, OutOfMemoryError for threads),
         // the task's finally block will never execute. We must release the lock here.

google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/AwsCredentialsTest.java

@@ -65,11 +65,6 @@ class AwsCredentialsTest extends BaseSerializationTest {
   @org.junit.jupiter.api.BeforeEach
   void setUp() {}
 
-  @org.junit.jupiter.api.AfterEach
-  void tearDown() {
-    RegionalAccessBoundary.setEnvironmentProviderForTest(null);
-  }
-
   private static final String STS_URL = "https://sts.googleapis.com/v1/token";
   private static final String AWS_CREDENTIALS_URL = "https://169.254.169.254";
   private static final String AWS_CREDENTIALS_URL_WITH_ROLE = "https://169.254.169.254/roleName";
@@ -1369,9 +1364,6 @@ public AwsSecurityCredentials getCredentials(ExternalAccountSupplierContext cont
 
   @Test
   public void testRefresh_regionalAccessBoundarySuccess() throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
 
     MockExternalAccountCredentialsTransportFactory transportFactory =
         new MockExternalAccountCredentialsTransportFactory();

google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/ComputeEngineCredentialsTest.java

@@ -80,11 +80,6 @@ class ComputeEngineCredentialsTest extends BaseSerializationTest {
   @org.junit.jupiter.api.BeforeEach
   void setUp() {}
 
-  @org.junit.jupiter.api.AfterEach
-  void tearDown() {
-    RegionalAccessBoundary.setEnvironmentProviderForTest(null);
-  }
-
   private static final URI CALL_URI = URI.create("http://googleapis.com/testapi/v1/foo");
 
   private static final String TOKEN_URL =
@@ -1188,9 +1183,6 @@ void getProjectId_explicitSet_noMDsCall() {
 
   @org.junit.jupiter.api.Test
   void refresh_regionalAccessBoundarySuccess() throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
 
     String defaultAccountEmail = "default@email.com";
     MockMetadataServerTransportFactory transportFactory = new MockMetadataServerTransportFactory();

google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/ExternalAccountAuthorizedUserCredentialsTest.java

@@ -130,9 +130,7 @@ void setup() {
   }
 
   @org.junit.jupiter.api.AfterEach
-  void tearDown() {
-    RegionalAccessBoundary.setEnvironmentProviderForTest(null);
-  }
+  void tearDown() {}
 
   @Test
   void builder_allFields() throws IOException {
@@ -1243,9 +1241,6 @@ void serialize() throws IOException, ClassNotFoundException {
 
   @org.junit.jupiter.api.Test
   void testRefresh_regionalAccessBoundarySuccess() throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
 
     ExternalAccountAuthorizedUserCredentials credentials =
         ExternalAccountAuthorizedUserCredentials.newBuilder()

google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/ExternalAccountCredentialsTest.java

@@ -92,11 +92,6 @@ void setup() {
     transportFactory = new MockExternalAccountCredentialsTransportFactory();
   }
 
-  @org.junit.jupiter.api.AfterEach
-  void tearDown() {
-    RegionalAccessBoundary.setEnvironmentProviderForTest(null);
-  }
-
   @Test
   void fromStream_identityPoolCredentials() throws IOException {
     GenericJson json = buildJsonIdentityPoolCredential();
@@ -1302,9 +1297,7 @@ public void getRegionalAccessBoundaryUrl_invalidAudience_throws() {
   @Test
   public void refresh_workload_regionalAccessBoundarySuccess()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     String audience =
         "//iam.googleapis.com/projects/12345/locations/global/workloadIdentityPools/my-pool/providers/my-provider";
 
@@ -1339,9 +1332,7 @@ public String retrieveSubjectToken() throws IOException {
   @Test
   public void refresh_workforce_regionalAccessBoundarySuccess()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     String audience =
         "//iam.googleapis.com/locations/global/workforcePools/my-pool/providers/my-provider";
 
@@ -1376,9 +1367,7 @@ public String retrieveSubjectToken() throws IOException {
   @Test
   public void refresh_impersonated_workload_regionalAccessBoundarySuccess()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     String projectNumber = "12345";
     String poolId = "my-pool";
     String providerId = "my-provider";
@@ -1440,9 +1429,7 @@ public void refresh_impersonated_workload_regionalAccessBoundarySuccess()
   @Test
   public void refresh_impersonated_workforce_regionalAccessBoundarySuccess()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     String poolId = "my-pool";
     String providerId = "my-provider";
     String audience =

google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/GoogleCredentialsTest.java

@@ -109,9 +109,7 @@ class GoogleCredentialsTest extends BaseSerializationTest {
   void setUp() {}
 
   @org.junit.jupiter.api.AfterEach
-  void tearDown() {
-    RegionalAccessBoundary.setEnvironmentProviderForTest(null);
-  }
+  void tearDown() {}
 
   @Test
   void getApplicationDefault_nullTransport_throws() {
@@ -858,9 +856,6 @@ void serialize() throws IOException, ClassNotFoundException {
 
   @Test
   public void serialize_removesStaleRabHeaders() throws Exception {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
 
     MockTokenServerTransportFactory transportFactory = new MockTokenServerTransportFactory();
     RegionalAccessBoundary rab =
@@ -1046,9 +1041,7 @@ void getCredentialInfo_impersonatedServiceAccount() throws IOException {
   @Test
   public void regionalAccessBoundary_shouldFetchAndReturnRegionalAccessBoundaryDataSuccessfully()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     MockTokenServerTransport transport = new MockTokenServerTransport();
     transport.addServiceAccount(SA_CLIENT_EMAIL, ACCESS_TOKEN);
     RegionalAccessBoundary regionalAccessBoundary =
@@ -1083,9 +1076,6 @@ public void regionalAccessBoundary_shouldFetchAndReturnRegionalAccessBoundaryDat
   @Test
   public void regionalAccessBoundary_shouldRetryRegionalAccessBoundaryLookupOnFailure()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
 
     // This transport will be used for the regional access boundary lookup.
     // We will configure it to fail on the first attempt.
@@ -1137,9 +1127,7 @@ public com.google.api.client.http.LowLevelHttpRequest buildRequest(
   @Test
   public void regionalAccessBoundary_refreshShouldNotThrowWhenNoValidAccessTokenIsPassed()
       throws IOException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     MockTokenServerTransport transport = new MockTokenServerTransport();
     // Return an expired access token.
     transport.addServiceAccount(SA_CLIENT_EMAIL, "expired-token");
@@ -1162,9 +1150,7 @@ public void regionalAccessBoundary_refreshShouldNotThrowWhenNoValidAccessTokenIs
   @Test
   public void regionalAccessBoundary_cooldownDoublingAndRefresh()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     MockTokenServerTransport transport = new MockTokenServerTransport();
     transport.addServiceAccount(SA_CLIENT_EMAIL, ACCESS_TOKEN);
     // Always fail lookup for now.
@@ -1224,9 +1210,7 @@ public void regionalAccessBoundary_cooldownDoublingAndRefresh()
 
   @Test
   public void regionalAccessBoundary_shouldFailOpenWhenRefreshCannotBeStarted() throws IOException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     // Use a simple AccessToken-based credential that won't try to refresh.
     GoogleCredentials credentials = GoogleCredentials.create(new AccessToken("some-token", null));
 
@@ -1238,9 +1222,7 @@ public void regionalAccessBoundary_shouldFailOpenWhenRefreshCannotBeStarted() th
   @Test
   public void regionalAccessBoundary_deduplicationOfConcurrentRefreshes()
       throws IOException, InterruptedException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     MockTokenServerTransport transport = new MockTokenServerTransport();
     transport.setRegionalAccessBoundary(
         new RegionalAccessBoundary("valid", Collections.singletonList("us-central1"), null));
@@ -1269,9 +1251,7 @@ public void regionalAccessBoundary_deduplicationOfConcurrentRefreshes()
 
   @Test
   public void regionalAccessBoundary_shouldSkipRefreshForRegionalEndpoints() throws IOException {
-    TestEnvironmentProvider environmentProvider = new TestEnvironmentProvider();
-    RegionalAccessBoundary.setEnvironmentProviderForTest(environmentProvider);
-    environmentProvider.setEnv(RegionalAccessBoundary.ENABLE_EXPERIMENT_ENV_VAR, "1");
+
     MockTokenServerTransport transport = new MockTokenServerTransport();
     GoogleCredentials credentials = createTestCredentials(transport);