Add NO_CREDENTIALS authentication type for GCS

lib/trino-filesystem-gcs/src/main/java/io/trino/filesystem/gcs/GcsFileSystemConfig.java

@@ -297,6 +297,11 @@ public boolean isRetryDelayValid()
     @AssertTrue(message = "Either gcs.auth-type or gcs.json-key or gcs.json-key-file-path must be set")
     public boolean isAuthMethodValid()
     {
+        // allow not specify any of configuration for SERVICE_ACCOUNT auth
+        if (getAuthType() == AuthType.SERVICE_ACCOUNT && jsonKey == null && jsonKeyFilePath == null) {
+            return true;
+        }
+
         if (getAuthType() == AuthType.ACCESS_TOKEN) {
             return jsonKey == null && jsonKeyFilePath == null;
         }

lib/trino-filesystem-gcs/src/main/java/io/trino/filesystem/gcs/GcsServiceAccountAuth.java

@@ -13,7 +13,9 @@
  */
 package io.trino.filesystem.gcs;
 
+import com.google.auth.Credentials;
 import com.google.auth.oauth2.GoogleCredentials;
+import com.google.cloud.NoCredentials;
 import com.google.cloud.storage.StorageOptions;
 import com.google.inject.Inject;
 import io.trino.spi.security.ConnectorIdentity;
@@ -29,7 +31,7 @@
 public class GcsServiceAccountAuth
         implements GcsAuth
 {
-    private final Optional<GoogleCredentials> jsonGoogleCredential;
+    private final Optional<Credentials> jsonGoogleCredential;
 
     @Inject
     public GcsServiceAccountAuth(GcsFileSystemConfig config)
@@ -56,18 +58,15 @@ else if (jsonKeyFilePath != null) {
     @Override
     public void setAuth(StorageOptions.Builder builder, ConnectorIdentity identity)
     {
-        GoogleCredentials credentials = jsonGoogleCredential.orElseGet(() -> {
+        Credentials credentials = jsonGoogleCredential.orElseGet(() -> {
             try {
                 return GoogleCredentials.getApplicationDefault();
             }
             catch (IOException e) {
-                // This is consistent with the GCP SDK when no credentials are available in the environment
-                return null;
+                return NoCredentials.getInstance();
             }
         });
 
-        if (credentials != null) {
-            builder.setCredentials(credentials);
-        }
+        builder.setCredentials(credentials);
     }
 }

lib/trino-filesystem-gcs/src/test/java/io/trino/filesystem/gcs/TestGcsFileSystemConfig.java

@@ -32,6 +32,7 @@
 import static io.airlift.units.DataSize.Unit.MEGABYTE;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.assertj.core.api.Assertions.assertThat;
 
 public class TestGcsFileSystemConfig
 {
@@ -136,7 +137,7 @@ public void testValidation()
         assertFailsValidation(
                 new GcsFileSystemConfig()
                         .setAuthType(AuthType.ACCESS_TOKEN)
-                        .setJsonKey("{}}"),
+                        .setJsonKey("{}"),
                 "authMethodValid",
                 "Either gcs.auth-type or gcs.json-key or gcs.json-key-file-path must be set",
                 AssertTrue.class);
@@ -198,4 +199,10 @@ public void testValidation()
                 "Cannot set both gcs.use-access-token and gcs.auth-type",
                 AssertFalse.class);
     }
+
+    @Test
+    void testAllowingNoConfigurationSpecifiedForServiceAccountAuth()
+    {
+        assertThat(new GcsFileSystemConfig().isAuthMethodValid()).isTrue();
+    }
 }

lib/trino-filesystem-gcs/src/test/java/io/trino/filesystem/gcs/TestGcsStorageFactory.java

@@ -14,6 +14,7 @@
 package io.trino.filesystem.gcs;
 
 import com.google.auth.Credentials;
+import com.google.cloud.NoCredentials;
 import com.google.cloud.storage.Storage;
 import com.google.cloud.storage.StorageOptions;
 import io.trino.spi.security.ConnectorIdentity;
@@ -27,8 +28,6 @@ final class TestGcsStorageFactory
     void testDefaultCredentials()
             throws Exception
     {
-        Credentials expectedCredentials = StorageOptions.newBuilder().build().getCredentials();
-
         // No credentials options are set
         GcsFileSystemConfig config = new GcsFileSystemConfig();
 
@@ -41,6 +40,8 @@ void testDefaultCredentials()
 
         assertThat(actualCredentials)
                 .as("if credentials are not explicitly configured, should have same behavior as the GCS client")
-                .isEqualTo(expectedCredentials);
+                .isEqualTo(NoCredentials.getInstance());
+
+        assertThat(StorageOptions.newBuilder().build().getCredentials()).isNull();
     }
 }