Fastapi: [QUESTION] How to use different middleware for different routes/path

[philippegirard]

First check

• [x] I used the GitHub search to find a similar issue and didn't find it.
• [x] I searched the FastAPI documentation, with the integrated search.
• [x] I already searched in Google "How to X in FastAPI" and didn't find any information.

Description

Is it possible to use different middleware for different routes/path?

Additional context

In my case my need comes from CORS. But, I am sure there is other cases than CORS requirements that someone would need different middlewares for different paths.

• I want myapi.com/path1 to allow origins of calls from myfrontend.com
• I want myapi.com/path2 to allow origins of calls from anywhere ('*') since it is a public facing api.

I checked if it was possible to add a middleware at a router level and did not find any documentation about it.

Code example

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware

app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=['myfrontend.com'],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# I want /path1 to allow only calls from 'myfrontend.com'
@app.get("/path1")
async def path1():
    return {"status": "alive"}

# I want /path2 to be a public facing api that can be accessed from anywhere ['*']
@app.get("/path2")
async def path2():
    return {"status": "alive"}

[Dustyposa]

I haven't use this way, but you can have a try.
How about use subapp?
documention

[philippegirard]

Thank you @Dustyposa this looks exactly like what I was looking for.

Here is a example implementation in case someone else stumble upon the same problem

# app1.py

from fastapi import FastAPI

app1 = FastAPI(openapi_prefix="/app1")

@app1.get("path1")
async def path1():
    return { "message": "app1"}

# app2.py

from fastapi import FastAPI

app2 = FastAPI(openapi_prefix="/app2")

@app1.get("path2")
async def path2():
    return { "message": "app2"}

# main.py

from fastapi import FastAPI
from app1 import app1
from app2 import app2


app1.add_middleware(
    CORSMiddleware,
    allow_origins=['myfrontend.com'],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# here we can add middlewares that are only for app2 and not executed on paths of app1
# the CORS policy is different for app2. (allows '*' instead of 'myfrontend.com')
app2.add_middleware(
    CORSMiddleware,
    allow_origins=['*'],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

app = FastAPI()

app.mount(app1, "/app1")
app.mount(app2, "/app2")

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

[tiangolo]

Thanks for your help here @Dustyposa :bowing_man: :cake:

And thanks for reporting back and closing the issue @philippegirard :rocket: