FastAPI and Pyzeebe

[aleksvidak]

I am using version pyzeebe 3.0.0rc4 along with FastAPI framework https://fastapi.tiangolo.com/.

We use start & stop app handlers from FastAPI to start and stop worker. Something like:

def create_start_app_handler(_: FastAPI) -> Callable:

    async def start_app() -> None:
        logger.info('Triggering events on app start')
        asyncio.create_task(worker.work())

    return start_app


def create_stop_app_handler(_: FastAPI) -> Callable:

    async def stop_app() -> None:
        logger.info('Triggering events on app stop')
        asyncio.create_task(worker.stop())

    return stop_app

We init worker with:
worker = ZeebeWorker(channel, max_task_count=2)
with Camunda Cloud channel.

After some time of inactivity on the worker and with triggering new task, we get an error:
Task exception was never retrieved future: <Task finished coro=<ZeebeWorker.work() done, defined at /usr/local/lib/python3.7/site-packages/pyzeebe/worker/worker.py:50> exception=<AioRpcError of RPC that terminated with: status = StatusCode.UNAUTHENTICATED details = "Received http2 header with status: 401" debug_error_string = "{"created":"@1631893046.722399663","description":"Received http2 :status header with non-200 OK status","file":"src/core/ext/filters/http/client/http_client_filter.cc","file_line":129,"grpc_message":"Received http2 header with status: 401","grpc_status":16,"value":"401"}" >>

Restarting the service helps, but again the same pattern repeats after some time of inactivity.

I am not sure whether it is something on our side or on the side of Pyzeebe. Any pointers would be helpful!

Maybe @JonatanMartens can help me out on this one 🙂

@kbakk did you encounter similar situation? I know from Camunda Cloud Slack channel you've been using FastAPI as well... 🙂

[kbakk]

Hi,

I have only used the sync client to launch a process, so I don't have something that could help here.

I did notice this in the async docs, maybe related:

Important
Save a reference to the result of this function, to avoid a task disappearing mid execution.

https://docs.python.org/3/library/asyncio-task.html#creating-tasks