Can I deploy a NiceGUI app to Posit Connect?

[zilch42]

Hi there,

I'm trying to test whether a python app built with NiceGUI will work on Posit Connect (I can't find any mention of the two together) before I get into learning it proper. NiceGUI is built on FastAPI so I hope it should work, but I'm currently stuck.

I'm just trying to upload the basic demo:

# app.py
from nicegui import ui

ui.label('Hello NiceGUI!')

ui.run()

I'm deploying it with:
rsconnect deploy fastapi -n rconnect --entrypoint app .

The deployment works but I get the following error on the Posit Connect logs when the app tries to start

2023/10/11 22:55:43.243207611 ERROR:    Traceback (most recent call last):
2023/10/11 22:55:43.243245111   File "/opt/rstudio-connect/mnt/app/python/env/lib/python3.9/site-packages/starlette/routing.py", line 677, in lifespan
2023/10/11 22:55:43.243275296     async with self.lifespan_context(app) as maybe_state:
2023/10/11 22:55:43.243276348   File "/opt/rstudio-connect/mnt/app/python/env/lib/python3.9/site-packages/starlette/routing.py", line 566, in __aenter__
2023/10/11 22:55:43.243296243     await self._router.startup()
2023/10/11 22:55:43.243306350   File "/opt/rstudio-connect/mnt/app/python/env/lib/python3.9/site-packages/starlette/routing.py", line 656, in startup
2023/10/11 22:55:43.243311926     handler()
2023/10/11 22:55:43.243312770   File "/opt/rstudio-connect/mnt/app/python/env/lib/python3.9/site-packages/nicegui/nicegui.py", line 75, in handle_startup
2023/10/11 22:55:43.243317822     raise RuntimeError('\n\n'
2023/10/11 22:55:43.243318250 RuntimeError: 
2023/10/11 22:55:43.243322835 
2023/10/11 22:55:43.243323595 You must call ui.run() to start the server.
2023/10/11 22:55:43.243330081 If ui.run() is behind a main guard
2023/10/11 22:55:43.243330511    if __name__ == "__main__":
2023/10/11 22:55:43.243334291 remove the guard or replace it with
2023/10/11 22:55:43.243334726    if __name__ in {"__main__", "__mp_main__"}:
2023/10/11 22:55:43.243338471 to allow for multiprocessing.
2023/10/11 22:55:43.243338936 

I've also tried

# app.py
from nicegui import ui

ui.label('Hello NiceGUI!')

app = ui.run()

and deploying it with:
rsconnect deploy fastapi -n rconnect --entrypoint app:app .

Any help would be greatly appreciated

[edavidaja]

In the NiceGUI documentation under server hosting, there is a reference to using a custom fastapi app to deploy: https://github.com/zauberzeug/nicegui/tree/main/examples/fastapi

I would try that.

[zilch42]

Thanks @edavidaja, that worked!

[rodja]

As discussed in How to deploy to Posit Connect · zauberzeug/nicegui · Discussion #1787 · GitHub the example can be further simplified to

from fastapi import FastAPI
from nicegui import app, ui

fastapi_app = FastAPI()

@ui.page('/')
def index():
    ui.label('Hello, FastAPI!')
    # NOTE dark mode will be persistent for each user across tabs and server restarts
    ui.dark_mode().bind_value(app.storage.user, 'dark_mode')
    ui.checkbox('dark mode').bind_value(app.storage.user, 'dark_mode')

ui.run_with(fastapi_app, storage_secret='secret')

if __name__ == '__main__':
    print('Please start with "uvicorn demo:fastapi_app --reload" (if your file is named "demo.py")')