feat: fail at startup when connections info is incorrect - DIA-38713 (#42)

Author: hadrien

fastapi_sqla/__init__.py

@@ -66,6 +66,17 @@ def startup():
     Base.metadata.bind = engine
     Base.prepare(engine)
     _Session.configure(bind=engine)
+
+    # Fail early:
+    try:
+        with open_session() as session:
+            session.execute("select 'OK'")
+    except Exception:
+        logger.critical(
+            "Fail querying db: is sqlalchemy_url envvar correctly configured?"
+        )
+        raise
+
     logger.info("startup", engine=engine)
 
 

fastapi_sqla/_pytest_plugin.py

@@ -78,7 +78,7 @@ def sqla_reflection(sqla_modules, sqla_connection, db_url):
 @fixture(autouse=True)
 def engine_from_config(request, db_url, sqla_connection, sqla_transaction):
     """So that all DB operations are never written to db for real."""
-    if "dont_patch_engine_from_config" in request.keywords:
+    if "dont_patch_engines" in request.keywords:
         yield
 
     else:
@@ -135,13 +135,19 @@ async def async_sqla_connection(async_engine, event_loop):
             await connection.rollback()
 
     @fixture(autouse=True)
-    async def patch_async_sessionmaker(async_sqlalchemy_url, async_sqla_connection):
+    async def patch_async_sessionmaker(
+        async_sqlalchemy_url, async_sqla_connection, request
+    ):
         """So that all async DB operations are never written to db for real."""
-        with patch(
-            "fastapi_sqla.asyncio_support.create_async_engine"
-        ) as create_async_engine:
-            create_async_engine.return_value = async_sqla_connection
-            yield create_async_engine
+        if "dont_patch_engines" in request.keywords:
+            yield
+
+        else:
+            with patch(
+                "fastapi_sqla.asyncio_support.create_async_engine"
+            ) as create_async_engine:
+                create_async_engine.return_value = async_sqla_connection
+                yield create_async_engine
 
     @fixture
     async def async_session(async_sqla_connection):

fastapi_sqla/asyncio_support.py

@@ -3,6 +3,7 @@
 
 import structlog
 from fastapi import Request
+from sqlalchemy import text
 from sqlalchemy.ext.asyncio import AsyncSession as SqlaAsyncSession
 from sqlalchemy.ext.asyncio import create_async_engine
 from sqlalchemy.orm.session import sessionmaker
@@ -12,10 +13,22 @@
 _AsyncSession = sessionmaker(class_=SqlaAsyncSession)
 
 
-def startup():
+async def startup():
     async_sqlalchemy_url = os.environ["async_sqlalchemy_url"]
-    async_engine = create_async_engine(async_sqlalchemy_url)
-    _AsyncSession.configure(bind=async_engine, expire_on_commit=False)
+    engine = create_async_engine(async_sqlalchemy_url)
+    _AsyncSession.configure(bind=engine, expire_on_commit=False)
+
+    # Fail early:
+    try:
+        async with open_session() as session:
+            await session.execute(text("select 'ok'"))
+    except Exception:
+        logger.critical(
+            "Fail querying db: is async_sqlalchemy_url envvar correctly configured?"
+        )
+        raise
+
+    logger.info("startup", async_engine=engine)
 
 
 class AsyncSession(SqlaAsyncSession):

tests/test_asyncio_support.py

@@ -5,17 +5,17 @@
 
 
 @fixture(autouse=True)
-def setup(environ):
+async def setup(environ):
     from fastapi_sqla.asyncio_support import startup
 
-    startup()
+    await startup()
     yield
 
 
 async def test_startup_configure_async_session():
     from fastapi_sqla.asyncio_support import _AsyncSession, startup
 
-    startup()
+    await startup()
 
     async with _AsyncSession() as session:
         res = await session.execute(text("SELECT 123"))

tests/test_startup.py

@@ -3,7 +3,7 @@
 import httpx
 from asgi_lifespan import LifespanManager
 from fastapi import FastAPI
-from pytest import fixture, mark
+from pytest import fixture, mark, raises
 from sqlalchemy import text
 
 
@@ -16,7 +16,7 @@ def case_sensitive_environ(environ, request):
         yield values
 
 
-@mark.dont_patch_engine_from_config
+@mark.dont_patch_engines
 def test_startup(case_sensitive_environ):
     from fastapi_sqla import _Session, startup
 
@@ -48,3 +48,26 @@ def now():
             res = await client.get("/one")
 
     assert res.json() == 1
+
+
+@mark.dont_patch_engines
+def test_startup_fail_on_bad_sqlalchemy_url(monkeypatch):
+    from fastapi_sqla import startup
+
+    monkeypatch.setenv("sqlalchemy_url", "postgresql://postgres@localhost/notexisting")
+
+    with raises(Exception):
+        startup()
+
+
+@mark.asyncio
+@mark.dont_patch_engines
+async def test_async_startup_fail_on_bad_async_sqlalchemy_url(monkeypatch):
+    from fastapi_sqla import asyncio_support
+
+    monkeypatch.setenv(
+        "async_sqlalchemy_url", "postgresql+asyncpg://postgres@localhost/notexisting"
+    )
+
+    with raises(Exception):
+        await asyncio_support.startup()