Host your Fastapi server on Heroku

Create a Fastapi project

for that install some pip packages

pip install fastapi

and you need a ASGI server for production
here we use uvicorn

pip install uvicron

and you need an another package named gunicorn

pip install gunicorn

write some code

Here we have to create a file for our python code. so create a file named main.py and write some code like this

from fastapi import FastAPI
app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

@app.get("/items/{item_id}")
def read_item(item_id: int, q: Optional[str] = None):
    return {"item_id": item_id, "q": q}

Run the code

uvicorn main:app --reload

this will run your app in localhost and the default port will be 8000. Here main is the filename and app is the fastapi object.

Next is adding some stuffs for hosting.

Create requirements.txt

for creating the file just run:

pip freeze > requirements.txt

it will create the file and contents like be this

anyio==3.4.0
asgiref==3.4.1
certifi==2021.10.8
charset-normalizer==2.0.9
click==8.0.3
fastapi==0.70.1
gunicorn==20.1.0
h11==0.12.0
idna==3.3
pydantic==1.8.2
requests==2.26.0
sniffio==1.2.0
starlette==0.16.0
typing-extensions==4.0.1
urllib3==1.26.7
uvicorn==0.16.0

Its the list of packages need to run your app.

Create Procfile

create a file named Procfile without any extensions and paste the below code

web: gunicorn -w 3 -k uvicorn.workers.UvicornWorker main:app

this contain the running script for execute your app
here main is the python file name and app is the fastapi object. so it can be changed..

Now the app is ready for deploy.

Create a Github Repo and push the code to it
and create a new heroku app linked with the respective github repo in heroku dashboard.

After bulid finished in heroku just go to your-app-url/docs for get your api documentation