fix(storage): cherry-pick validation upload memory fix to staging

src/webapp/gcsutil.py

@@ -1,8 +1,9 @@
 """Cloud storage related helper functions."""
 
 import datetime
-import io
 import logging
+import os
+import tempfile
 from typing import Any, Dict, List, Optional
 
 import pandas as pd
@@ -22,6 +23,41 @@
 SIGNED_URL_EXPIRY_MIN = 30
 
 
+def _unlink_if_exists(path: Optional[str]) -> None:
+    """Remove a file if path is set; ignore missing file or permission errors."""
+    if path is None:
+        return
+    try:
+        os.unlink(path)
+    except OSError:
+        pass
+
+
+def _download_blob_to_temp_csv_path(blob: Any, file_name: str) -> str:
+    """
+    Stream GCS blob to a private temp CSV path for validation.
+
+    Raises:
+        OSError: If download fails (after logging errno/context). Temp file is removed.
+    """
+    fd, csv_path = tempfile.mkstemp(suffix=".csv", prefix="validate_upload_")
+    os.close(fd)
+    try:
+        blob.download_to_filename(csv_path)
+    except OSError as e:
+        logger.error(
+            "GCS download_to_filename failed for %r temp_path=%r errno=%s strerror=%s",
+            file_name,
+            csv_path,
+            e.errno,
+            e.strerror,
+            exc_info=True,
+        )
+        _unlink_if_exists(csv_path)
+        raise
+    return csv_path
+
+
 def rename_file(
     bucket_name: str,
     file_name: str,
@@ -423,16 +459,17 @@ def _run_validation_and_get_normalized_df(
         institution_identifier: Optional[str],
     ) -> tuple[List[str], Any]:
         """Run validation on blob content; return inferred schema names and normalized DataFrame."""
+        local_csv_path: Optional[str] = None
         try:
-            with blob.open("r") as file:
-                result = validate_file_reader(
-                    file,
-                    allowed_schemas,
-                    base_schema,
-                    inst_schema,
-                    institution_id=institution_id,
-                    institution_identifier=institution_identifier,
-                )
+            local_csv_path = _download_blob_to_temp_csv_path(blob, file_name)
+            result = validate_file_reader(
+                local_csv_path,
+                allowed_schemas,
+                base_schema,
+                inst_schema,
+                institution_id=institution_id,
+                institution_identifier=institution_identifier,
+            )
             inferred_schema_names = [str(s) for s in result.get("schemas", [])]
             logging.debug(
                 "Validation successful for %s: %s", file_name, inferred_schema_names
@@ -447,20 +484,40 @@ def _run_validation_and_get_normalized_df(
             # Log any other error with context before re-raising (no silent failures).
             logging.exception("Validation failed for %s: %s", file_name, e)
             raise
+        finally:
+            _unlink_if_exists(local_csv_path)
 
     def _write_dataframe_to_gcs_as_csv(
         self, bucket: Any, blob_name: str, normalized_df: pd.DataFrame
     ) -> None:
         """Write a DataFrame to GCS as UTF-8 CSV. Used for validated/ output."""
-        csv_buffer = io.StringIO()
-        normalized_df.to_csv(
-            csv_buffer, index=False, encoding="utf-8", lineterminator="\n"
-        )
-        blob = bucket.blob(blob_name)
-        blob.upload_from_string(
-            csv_buffer.getvalue().encode("utf-8"),
-            content_type="text/csv; charset=utf-8",
-        )
+        fd, local_csv_path = tempfile.mkstemp(suffix=".csv", prefix="validated_out_")
+        os.close(fd)
+        try:
+            try:
+                normalized_df.to_csv(
+                    local_csv_path,
+                    index=False,
+                    encoding="utf-8",
+                    lineterminator="\n",
+                )
+            except OSError as e:
+                logger.error(
+                    "to_csv failed for validated blob %r temp_path=%r errno=%s strerror=%s",
+                    blob_name,
+                    local_csv_path,
+                    e.errno,
+                    e.strerror,
+                    exc_info=True,
+                )
+                raise
+            blob = bucket.blob(blob_name)
+            blob.upload_from_filename(
+                local_csv_path,
+                content_type="text/csv; charset=utf-8",
+            )
+        finally:
+            _unlink_if_exists(local_csv_path)
 
     def get_file_contents(self, bucket_name: str, file_name: str) -> Any:
         """Returns a file as a bytes object."""

src/webapp/gcsutil_test.py

@@ -1,6 +1,8 @@
 """Tests for gcsutil.StorageControl validation and normalized/raw archive flow."""
 
-import io
+import errno
+import os
+import tempfile
 from typing import Any
 from unittest.mock import MagicMock, patch
 
@@ -182,6 +184,14 @@ def blob_side_effect(name: str) -> Any:
     mock_client.bucket.return_value = mock_bucket
 
     small_df = pd.DataFrame({"col_a": [1, 2], "col_b": ["x", "y"]})
+    uploaded_chunks: list[bytes] = []
+
+    def capture_validated_upload(path: str, **kwargs: Any) -> None:
+        with open(path, "rb") as f:
+            uploaded_chunks.append(f.read())
+
+    mock_validated_blob.upload_from_filename.side_effect = capture_validated_upload
+
     control = StorageControl()
     with patch("src.webapp.gcsutil.storage.Client", return_value=mock_client):
         with patch.object(
@@ -201,13 +211,14 @@ def blob_side_effect(name: str) -> Any:
         mock_unvalidated_blob, mock_bucket, "raw/cohort.csv"
     )
     mock_unvalidated_blob.delete.assert_called_once()
-    # _write_dataframe_to_gcs_as_csv is called; it does bucket.blob(validated_blob_name).upload_from_string
+    # _write_dataframe_to_gcs_as_csv uploads from a temp file via upload_from_filename
     assert mock_bucket.blob.call_count >= 2
-    mock_validated_blob.upload_from_string.assert_called_once()
-    call_args = mock_validated_blob.upload_from_string.call_args
-    assert call_args.kwargs["content_type"] == "text/csv; charset=utf-8"
-    uploaded = call_args.args[0]
-    assert isinstance(uploaded, bytes)
+    mock_validated_blob.upload_from_filename.assert_called_once()
+    assert mock_validated_blob.upload_from_filename.call_args.kwargs[
+        "content_type"
+    ] == ("text/csv; charset=utf-8")
+    assert len(uploaded_chunks) == 1
+    uploaded = uploaded_chunks[0]
     assert b"col_a,col_b" in uploaded
     assert b"1,x" in uploaded
 
@@ -251,9 +262,12 @@ def test_validate_file_propagates_hard_validation_error() -> None:
 def test_run_validation_and_get_normalized_df_returns_names_and_df() -> None:
     """Returns (inferred_schema_names, normalized_df) when validation succeeds."""
     mock_blob = MagicMock()
-    mock_file = io.StringIO("foo_col,bar_col\n1,a\n2,b\n")
-    mock_blob.open.return_value.__enter__ = lambda self: mock_file
-    mock_blob.open.return_value.__exit__ = lambda self, *args: None
+
+    def download_to_path(path: str) -> None:
+        with open(path, "w", encoding="utf-8", newline="") as f:
+            f.write("foo_col,bar_col\n1,a\n2,b\n")
+
+    mock_blob.download_to_filename.side_effect = download_to_path
 
     control = StorageControl()
     with patch("src.webapp.gcsutil.validate_file_reader") as mock_validate:
@@ -281,9 +295,7 @@ def test_run_validation_and_get_normalized_df_propagates_hard_validation_error()
 ):
     """HardValidationError is re-raised without wrapping."""
     mock_blob = MagicMock()
-    mock_file = io.StringIO("bad")
-    mock_blob.open.return_value.__enter__ = lambda self: mock_file
-    mock_blob.open.return_value.__exit__ = lambda self, *args: None
+    mock_blob.download_to_filename.side_effect = lambda p: open(p, "w").close()
 
     control = StorageControl()
     with patch(
@@ -298,9 +310,7 @@ def test_run_validation_and_get_normalized_df_propagates_hard_validation_error()
 def test_run_validation_and_get_normalized_df_propagates_value_error() -> None:
     """ValueError from validate_file_reader (e.g. encoding) is re-raised."""
     mock_blob = MagicMock()
-    mock_file = io.StringIO("data")
-    mock_blob.open.return_value.__enter__ = lambda self: mock_file
-    mock_blob.open.return_value.__exit__ = lambda self, *args: None
+    mock_blob.download_to_filename.side_effect = lambda p: open(p, "w").close()
 
     control = StorageControl()
     with patch(
@@ -316,9 +326,7 @@ def test_run_validation_and_get_normalized_df_propagates_value_error() -> None:
 def test_run_validation_and_get_normalized_df_propagates_unicode_error() -> None:
     """UnicodeError from validate_file_reader (e.g. decode) is re-raised."""
     mock_blob = MagicMock()
-    mock_file = io.StringIO("data")
-    mock_blob.open.return_value.__enter__ = lambda self: mock_file
-    mock_blob.open.return_value.__exit__ = lambda self, *args: None
+    mock_blob.download_to_filename.side_effect = lambda p: open(p, "w").close()
 
     control = StorageControl()
     with patch(
@@ -343,13 +351,123 @@ def test_write_dataframe_to_gcs_as_csv_uploads_utf8_csv() -> None:
     mock_bucket.blob.return_value = mock_blob
 
     df = pd.DataFrame({"A": [1, 2], "B": ["a", "b"]})
+
+    def assert_csv_at_path(path: str, **kwargs: Any) -> None:
+        with open(path, "r", encoding="utf-8") as f:
+            assert f.read().strip() == "A,B\n1,a\n2,b"
+
+    mock_blob.upload_from_filename.side_effect = assert_csv_at_path
+
     control = StorageControl()
     control._write_dataframe_to_gcs_as_csv(mock_bucket, "validated/out.csv", df)
 
     mock_bucket.blob.assert_called_once_with("validated/out.csv")
-    mock_blob.upload_from_string.assert_called_once()
-    call_args = mock_blob.upload_from_string.call_args
-    assert call_args.kwargs["content_type"] == "text/csv; charset=utf-8"
-    payload = call_args.args[0]
-    assert isinstance(payload, bytes)
-    assert payload.decode("utf-8").strip() == "A,B\n1,a\n2,b"
+    mock_blob.upload_from_filename.assert_called_once()
+    assert mock_blob.upload_from_filename.call_args.kwargs["content_type"] == (
+        "text/csv; charset=utf-8"
+    )
+
+
+def test_run_validation_download_oserror_unlinks_temp_and_skips_validate() -> None:
+    """If GCS download fails, temp file is removed and validate_file_reader is not run."""
+    fd, real_path = tempfile.mkstemp(suffix=".csv", prefix="test_dl_oserr_")
+    mock_blob = MagicMock()
+    mock_blob.download_to_filename.side_effect = OSError(
+        errno.ENOSPC, "No space left on device"
+    )
+
+    control = StorageControl()
+    with patch("src.webapp.gcsutil.tempfile.mkstemp", return_value=(fd, real_path)):
+        with patch("src.webapp.gcsutil.validate_file_reader") as mock_validate:
+            with pytest.raises(OSError, match="No space left"):
+                control._run_validation_and_get_normalized_df(
+                    mock_blob,
+                    "school_course.csv",
+                    ["STUDENT"],
+                    {},
+                    None,
+                    "pdp",
+                    None,
+                )
+            mock_validate.assert_not_called()
+
+    assert not os.path.exists(real_path)
+    mock_blob.download_to_filename.assert_called_once_with(real_path)
+
+
+def test_run_validation_download_oserror_logs_errno() -> None:
+    """OSError from download_to_filename is logged with errno before re-raise."""
+    fd, real_path = tempfile.mkstemp(suffix=".csv", prefix="test_dl_log_")
+    mock_blob = MagicMock()
+    mock_blob.download_to_filename.side_effect = OSError(
+        errno.ENOSPC, "No space left on device"
+    )
+
+    control = StorageControl()
+    with patch("src.webapp.gcsutil.tempfile.mkstemp", return_value=(fd, real_path)):
+        with patch("src.webapp.gcsutil.logger") as mock_logger:
+            with pytest.raises(OSError):
+                control._run_validation_and_get_normalized_df(
+                    mock_blob,
+                    "f.csv",
+                    ["STUDENT"],
+                    {},
+                    None,
+                    "pdp",
+                    None,
+                )
+            mock_logger.error.assert_called_once()
+            msg = mock_logger.error.call_args[0][0]
+            assert "download_to_filename failed" in msg
+            assert mock_logger.error.call_args[0][3] == errno.ENOSPC
+
+    assert not os.path.exists(real_path)
+
+
+def test_write_dataframe_to_csv_oserror_unlinks_temp() -> None:
+    """If to_csv fails (e.g. disk full), temp file is removed and upload is not attempted."""
+    fd, real_path = tempfile.mkstemp(suffix=".csv", prefix="test_csv_oserr_")
+    mock_blob = MagicMock()
+    mock_bucket = MagicMock()
+    mock_bucket.blob.return_value = mock_blob
+
+    control = StorageControl()
+    with patch("src.webapp.gcsutil.tempfile.mkstemp", return_value=(fd, real_path)):
+        with patch.object(
+            pd.DataFrame,
+            "to_csv",
+            side_effect=OSError(errno.ENOSPC, "No space left on device"),
+        ):
+            with patch("src.webapp.gcsutil.logger") as mock_logger:
+                with pytest.raises(OSError, match="No space left"):
+                    control._write_dataframe_to_gcs_as_csv(
+                        mock_bucket,
+                        "validated/out.csv",
+                        pd.DataFrame({"a": [1]}),
+                    )
+                mock_logger.error.assert_called_once()
+                assert "to_csv failed" in mock_logger.error.call_args[0][0]
+                assert mock_logger.error.call_args[0][3] == errno.ENOSPC
+
+    assert not os.path.exists(real_path)
+    mock_blob.upload_from_filename.assert_not_called()
+
+
+def test_write_dataframe_upload_failure_still_unlinks_temp() -> None:
+    """If GCS upload fails after to_csv, the local temp file is still deleted."""
+    fd, real_path = tempfile.mkstemp(suffix=".csv", prefix="test_upload_fail_")
+    mock_blob = MagicMock()
+    mock_blob.upload_from_filename.side_effect = RuntimeError("upload failed")
+    mock_bucket = MagicMock()
+    mock_bucket.blob.return_value = mock_blob
+
+    control = StorageControl()
+    with patch("src.webapp.gcsutil.tempfile.mkstemp", return_value=(fd, real_path)):
+        with pytest.raises(RuntimeError, match="upload failed"):
+            control._write_dataframe_to_gcs_as_csv(
+                mock_bucket,
+                "validated/out.csv",
+                pd.DataFrame({"x": [1]}),
+            )
+
+    assert not os.path.exists(real_path)