fix(vertex/files): keep legacy bucket_name as GCS bucket fallback

The rename to gcs_bucket_name dropped the legacy bucket_name key entirely, so an SDK caller passing bucket_name to a Vertex AI file create/retrieve/content call with GCS_BUCKET_NAME unset got ValueError("GCS bucket_name is required") where it previously resolved the bucket. _get_configured_bucket_name now reads gcs_bucket_name, then bucket_name, then the env var, and bucket_name is restored to OPTIONAL_KWARGS_KEYS so it survives get_litellm_params on the retrieve and content paths. gcs_bucket_name keeps precedence when both are present

litellm/litellm_core_utils/get_litellm_params.py

@@ -15,6 +15,7 @@ OPTIONAL_KWARGS_KEYS = frozenset(
         "azure_scope",
         "timeout",
         "gcs_bucket_name",
+        "bucket_name",
         "vertex_credentials",
         "vertex_project",
         "vertex_location",

litellm/llms/vertex_ai/files/transformation.py

@@ -360,8 +360,10 @@ class VertexAIFilesConfig(VertexBase, BaseFilesConfig):
         )
 
     def _get_configured_bucket_name(self, litellm_params: Dict) -> str:
-        bucket_name = litellm_params.get("gcs_bucket_name") or os.getenv(
-            "GCS_BUCKET_NAME"
+        bucket_name = (
+            litellm_params.get("gcs_bucket_name")
+            or litellm_params.get("bucket_name")
+            or os.getenv("GCS_BUCKET_NAME")
         )
         if not bucket_name:
             raise ValueError("GCS bucket_name is required")

tests/test_litellm/llms/vertex_ai/files/test_vertex_ai_files_transformation.py

@@ -1274,3 +1274,47 @@ class TestVertexBatchCustomIdLabels:
         raw_label = vertex_input[0]["request"]["labels"]["litellm_custom_id_raw"]
         assert raw_label != "MyRequest-1"
         assert _sanitize_gcp_label_value(raw_label) == raw_label
+
+
+class TestConfiguredBucketNameResolution:
+    def test_should_resolve_new_gcs_bucket_name_key(self, config, monkeypatch):
+        monkeypatch.delenv("GCS_BUCKET_NAME", raising=False)
+        assert (
+            config._get_configured_bucket_name({"gcs_bucket_name": "my-new-bucket"})
+            == "my-new-bucket"
+        )
+
+    def test_should_resolve_legacy_bucket_name_key(self, config, monkeypatch):
+        monkeypatch.delenv("GCS_BUCKET_NAME", raising=False)
+        assert (
+            config._get_configured_bucket_name({"bucket_name": "my-legacy-bucket"})
+            == "my-legacy-bucket"
+        )
+
+    def test_should_prefer_new_key_over_legacy(self, config, monkeypatch):
+        monkeypatch.delenv("GCS_BUCKET_NAME", raising=False)
+        assert (
+            config._get_configured_bucket_name(
+                {"gcs_bucket_name": "new", "bucket_name": "legacy"}
+            )
+            == "new"
+        )
+
+    def test_should_fall_back_to_env(self, config, monkeypatch):
+        monkeypatch.setenv("GCS_BUCKET_NAME", "env-bucket")
+        assert config._get_configured_bucket_name({}) == "env-bucket"
+
+    def test_should_raise_when_no_bucket_anywhere(self, config, monkeypatch):
+        monkeypatch.delenv("GCS_BUCKET_NAME", raising=False)
+        with pytest.raises(ValueError, match="GCS bucket_name is required"):
+            config._get_configured_bucket_name({})
+
+    def test_legacy_kwarg_survives_get_litellm_params(self):
+        from litellm.litellm_core_utils.get_litellm_params import (
+            OPTIONAL_KWARGS_KEYS,
+            get_litellm_params,
+        )
+
+        assert "bucket_name" in OPTIONAL_KWARGS_KEYS
+        params = get_litellm_params(bucket_name="my-legacy-bucket")
+        assert params.get("bucket_name") == "my-legacy-bucket"