Add auth foundation and app DB management

app/auth_db.py

@@ -0,0 +1,53 @@
+from collections.abc import Generator
+from functools import lru_cache
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
+
+from app.config import get_settings
+
+
+class AuthBase(DeclarativeBase):
+    pass
+
+
+def _build_connect_args(database_url: str) -> dict[str, object]:
+    connect_args: dict[str, object] = {}
+    if database_url.startswith("sqlite"):
+        connect_args["check_same_thread"] = False
+    return connect_args
+
+
+@lru_cache
+def _get_auth_engine(database_url: str):
+    return create_engine(database_url, connect_args=_build_connect_args(database_url))
+
+
+@lru_cache
+def _get_auth_session_local(database_url: str):
+    engine = _get_auth_engine(database_url)
+    return sessionmaker(bind=engine, autoflush=False, autocommit=False, class_=Session)
+
+
+def get_auth_engine():
+    settings = get_settings()
+    return _get_auth_engine(settings.app_database_url)
+
+
+def get_auth_session_local():
+    settings = get_settings()
+    return _get_auth_session_local(settings.app_database_url)
+
+
+def reset_auth_db_caches() -> None:
+    _get_auth_session_local.cache_clear()
+    _get_auth_engine.cache_clear()
+
+
+def get_auth_db_session() -> Generator[Session, None, None]:
+    session_local = get_auth_session_local()
+    session = session_local()
+    try:
+        yield session
+    finally:
+        session.close()