feat: Add alembic log path as env var change (#4272)

* Added alembic log path as env var change

* [autofix.ci] apply automated fixes

* Improved platform independence of path check

* fix: arg-type mypy error

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Ítalo Johnny <[email protected]>

src/backend/base/langflow/services/database/service.py

@@ -44,6 +44,15 @@ def __init__(self, settings_service: SettingsService):
         self.script_location = langflow_dir / "alembic"
         self.alembic_cfg_path = langflow_dir / "alembic.ini"
         self.engine = self._create_engine()
+        alembic_log_file = self.settings_service.settings.alembic_log_file
+
+        # Check if the provided path is absolute, cross-platform.
+        if Path(alembic_log_file).is_absolute():
+            # Use the absolute path directly.
+            self.alembic_log_path = Path(alembic_log_file)
+        else:
+            # Construct the path using the langflow directory.
+            self.alembic_log_path = Path(langflow_dir) / alembic_log_file
 
     def reload_engine(self) -> None:
         self.engine = self._create_engine()
@@ -178,7 +187,7 @@ def run_migrations(self, *, fix=False) -> None:
         # which is a buffer
         # I don't want to output anything
         # subprocess.DEVNULL is an int
-        with (self.script_location / "alembic.log").open("w", encoding="utf-8") as buffer:
+        with self.alembic_log_path.open("w", encoding="utf-8") as buffer:
             alembic_cfg = Config(stdout=buffer)
             # alembic_cfg.attributes["connection"] = session
             alembic_cfg.set_main_option("script_location", str(self.script_location))

src/backend/base/langflow/services/settings/base.py

@@ -157,6 +157,8 @@ class Settings(BaseSettings):
     """The log level for Langflow."""
     log_file: str | None = "logs/langflow.log"
     """The path to log file for Langflow."""
+    alembic_log_file: str = "alembic/alembic.log"
+    """The path to log file for Alembic for SQLAlchemy."""
     frontend_path: str | None = None
     """The path to the frontend directory containing build files. This is for development purposes only.."""
     open_browser: bool = False