POST volume: return 422 when invalid node ID is passed

[boddumanohar]

When I passed incorrect storage-node-id as a part of volume create, it failed with 500 error. So handling this gracefully.

26-06-08 08:36:41,704: 140277069612736: INFO: Adding LVol: pvc-4709f037-654b-416f-8d80-74ee13b041b0
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/uvicorn/protocols/http/h11_impl.py", line 415, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/uvicorn/middleware/proxy_headers.py", line 62, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/fastapi/applications.py", line 1159, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/applications.py", line 90, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/base.py", line 191, in __call__
    with recv_stream, send_stream, collapse_excgroups():
                                   ^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/contextlib.py", line 158, in __exit__
    self.gen.throw(value)
  File "/usr/local/lib/python3.12/site-packages/starlette/_utils.py", line 87, in collapse_excgroups
    raise exc
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/base.py", line 193, in __call__
    response = await self.dispatch_func(request, call_next)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/simplyblock_web/app.py", line 49, in dispatch
    response = await call_next(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/base.py", line 168, in call_next
    raise app_exc from app_exc.__cause__ or app_exc.__context__
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/base.py", line 144, in coro
    await self.app(scope, receive_or_disconnect, send_no_error)
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 63, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.12/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 660, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 680, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 276, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/fastapi/routing.py", line 134, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.12/site-packages/fastapi/routing.py", line 120, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/fastapi/routing.py", line 674, in app
    raw_response = await run_endpoint_function(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/fastapi/routing.py", line 330, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/starlette/concurrency.py", line 32, in run_in_threadpool
    return await anyio.to_thread.run_sync(func)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/anyio/to_thread.py", line 63, in run_sync
    return await get_async_backend().run_sync_in_worker_thread(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2518, in run_sync_in_worker_thread
    return await future
           ^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 1002, in run
    result = context.run(func, *args)
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/simplyblock_web/api/v2/volume.py", line 113, in add
    raise ValueError(error)
ValueError: Can not find storage node: 11b5520f-af61-4c7c-b714-c8ca20954e4c

[mxsrc]

This is not a validation error, the format of the value you passed in is a correct ID, just that there is no node with that ID. This should yield a 404. The problem is, that we can't simply return a 404 on any error from the backend function, because there may be other failures. To get a proper handling of this, there are two options:

• Look up the storage node before calling the add-lvol function to confirm it exists, or introduce an existence check into the database
• Return meaningful errors from the lvol_controller that can be mapped to HTTP codes.