How to run with Fastapi/Uvicorn

[ryanking8215]

a small hy script by Fastapi and uvicorn

(import fastapi [FastAPI])
(import uvicorn)
(require hyrule *)

(setv app (FastAPI))

((app.get "/")
  (fn :async []
    {"message" "Hello, world"}))


(defmain []
  (uvicorn.run "app:app" :host "0.0.0.0" :port 8300 :reload True))

When run it, got

$ .venv/bin/hy app.hy
INFO:     Will watch for changes in these directories: ['./lab/hy/web_demo']
INFO:     Uvicorn running on http://0.0.0.0:8300 (Press CTRL+C to quit)
INFO:     Started reloader process [54412] using StatReload
Traceback (most recent call last):
  File "./lab/hy/web_demo/.venv/bin/hy", line 8, in <module>
    sys.exit(hy_main())
             ~~~~~~~^^
  File "<string>", line 1, in <module>
NameError: name 'from' is not defined
Traceback (most recent call last):
  File "./lab/hy/web_demo/.venv/bin/hy", line 8, in <module>
    sys.exit(hy_main())
             ~~~~~~~^^
  File "<string>", line 1, in <module>
NameError: name 'from' is not defined

uvicorn runs failed, seems it can't recognize "app:app" I guess, I have no idea how to fix it since the python version is ok.

[Kodiologist]

I haven't used these libraries, but if they expect a Python script, try giving them a minimal Python script that imports your Hy code.

[ryanking8215]

"app:app" is not a separate Python script, it is the script itself. "app:app" is form of "module:attribute", what is the first parameter of uvicorn.run() as documented in "https://www.uvicorn.org/settings/".

The first "app" means the python module("app.py" here), the second "app" is the FastAPI instance created in "app.py".

python version

# file: app.py

app=FastAPI()

@app.get("/")
async def root():
    return {"message": "hello, world"}

if __name__=='__main__':
   uvicorn.run("app:app", host="0.0.0.0", port=8030, reload=True)

if the filename changes to "main.py", it would be uvicorn.run("main:app", ...).

The python version runs ok. But for hy version, it runs failed. Seems it can't recognize "app:app", there is no python module named "app"?

[pyx]

Any library with its own import magic (dynamic loading from string via "importlib") would not work with standalone .hy script, as hy have no chance to setup the import hook, afaik.

Either:

1. put application script into its own package, e.g.

     |--- todo
            |--- __init__.py
            |--- app.hy
   

   __init__.py:

   import hy  # noqa
   

   This way, when the harness script (uvicorn in this case) load the package, hy's import hook will be triggered, so you can uvicorn todo.app:app --reload --reload-include '*.hy'

2. Write a launch script,
   If in python, make sure import hy before you call uvicorn.run:

   import uvicorn
   import hy  # noqa
   ...
   uvicorn.run("app:app", reload=True)

   If in hy, you don't have to do anything special:

   (import uvicorn)
   ...
   (uvicorn.run "app:app" :reload True)

Off topic:
This is the reason that I gave up on Sanic and many other async frameworks and using SQLAlchemy instead of other 'user-friendly` ORMs such as Tortoise ORM.

[ryanking8215]

I don't understand why you give up the async frameworks.

As I know, the traditional frameworks like Flask, Django..., they all use WSGI server to run like gunicorn or uWSGI as well as the uvicorn for async frameworks. Is there any difference?

[pyx]

I don't understand why you give up the async frameworks.

As I know, the traditional frameworks like Flask, Django..., they all use WSGI server to run like gunicorn or uWSGI as well as the uvicorn for async frameworks. Is there any difference?

I didn't give up on async web frameworks, I meant I don't like to circumvent the import limitation by writing my own extra code, so I chose Starlette + SQLAlchemy2 /w async driver.

See what I have been working on here #2608 (comment)

[ryanking8215]

That's because you tried method 1 first, if you tried method 2 first, then method 1 will get this error, because you most likely forget to stop the server. XD

No, I quit the method 1 server.
Besides that, the two methods I tried listened on different port actually. The method 1 server listened on 8000 which is the default port of uvicorn. Method 2 listened on port 8030 which I wrote in the py script.
And I check port usage before method 2 running in later tests.

[ryanking8215]

See what I have been working on here #2608 (comment)

defmodel is more elegant than native SQLAlchemy. Did you publish the macro somewhere or it is private? I am a newbie in Lisp family.

[pyx]

That's because you tried method 1 first, if you tried method 2 first, then method 1 will get this error, because you most likely forget to stop the server. XD

No, I quit the method 1 server. Besides that, the two methods I tried listened on different port actually. The method 1 server listened on 8000 which is the default port of uvicorn. Method 2 listened on port 8030 which I wrote in the py script. And I check port usage before method 2 running in later tests.

That's weird, it literally said "address already in use", did you put the uvicorn call and the app object in the same script?

defmodel is more elegant than native SQLAlchemy. Did you publish the macro somewhere or it is private? I am a newbie in Lisp family.

It will be on PyPI when it's done.