Starting fastapi with on_event() from user-supplied CLI arguments

[dineshbvadhia]

First Check

• I added a very descriptive title to this issue.
• I used the GitHub search to find a similar issue and didn't find it.
• I searched the FastAPI documentation, with the integrated search.
• I already searched in Google "How to X in FastAPI" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to FastAPI but to Pydantic.
• I already checked if it is not related to FastAPI but to Swagger UI.
• I already checked if it is not related to FastAPI but to ReDoc.

Commit to Help

• I commit to help with one of those options 👆

Example Code

app = FastAPI()
    
@app.get("/item")
def do_get_item(p3):
    return get_item()

@app.on_event("startup")
def app_startup(p1, p2):
    do_startup_stuff(p1, p2)

@app.on_event("shutdown")
def app_shutdown(p4):
    do_shutdown_stuff(p4)

def main(args):
    p1 = args[0]
    p2 = args[1]

    uvicorn.run(app)

if __name__ == "__main__":
    main(sys.argv)


Command Line 
> python myapp.py --p1 avatar2 --p2 watery

Description

This question is (sort-of) related to #4706 (comment).

I want to startup fastapi with user-supplied command line arguments and also initiate the on_event('startup') function. The arguments p1 and p2 differ depending on user/usage.

The error is: TypeError: app_startup() missing 2 required positional arguments: 'p1' and 'p2'

How can this be achieved? Thanks

Operating System

Windows

Operating System Details

No response

FastAPI Version

fastapi-0.88.0, starlette-0.22.0

Python Version

3.10.7

Additional Context

No response

[jgould22]

In this case you can just do something like this.

app = FastAPI()
    
@app.get("/item")
def do_get_item(p3):
    return get_item()

@app.on_event("startup")
def app_startup():
    p1 = sys.argv[0]
    p2 = sys.argv[1]
    print(p1, p2)
    # do_startup_stuff(p1, p2)

@app.on_event("shutdown")
def app_shutdown():
    p4 = sys.argv[1]
    print(p4)
    # do_shutdown_stuff(p4)


if __name__ == "__main__":
    uvicorn.run(app)

If these require a more complicated configuration usually in fast api this is done by using a settings/config object which you can learn more about here https://fastapi.tiangolo.com/advanced/settings/#create-the-settings-object

[dineshbvadhia]

Apologies for the tardy response. The solution is perfect for me. Thank-you so much :)