Docker-compose FastAPI --reload - docker-compose

Question

I have FastAPI app running in docker docker container. It works well except only one thing
The app doesn't reload if any changes. The changes applied only if i restart the container. But i wonder why it doesn't reload app if i put in command --reload flag?
I understand that docker itself do not reload if some changes in code. But app must be if flag --reload in command .
If I misunderstand, please advise how to achieve what i want. Thanks
main.py
from typing import Optional
import uvicorn
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}
if __name__ == '__main__':
uvicorn.run(app, host="0.0.0.0", port=8000, reload=True)
docker-compose.yml
version: "3"
services:
web:
build: .
restart: always
command: bash -c "uvicorn main:app --host 0.0.0.0 --port 8000 --reload"
volumes:
- .:/code
ports:
- "8000:8000"
depends_on:
- db
db:
image: postgres
ports:
- "50009:5432"
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
- POSTGRES_DB=test_db

Answer 1

this works for me
version: "3.9"
services:
people:
container_name: people
build: .
working_dir: /code/app
command: uvicorn main:app --host 0.0.0.0 --reload
environment:
DEBUG: 1
volumes:
- ./app:/code/app
ports:
- 8008:8000
restart: on-failure
this is my directory structure
.
├── Dockerfile
├── Makefile
├── app
│ └── main.py
├── docker-compose.yml
└── requirements.txt
make sure working_dir and volumes section's - ./app:/code/app match
example run:
docker-compose up --build
...
Attaching to people
people | INFO: Will watch for changes in these directories: ['/code/app']

Answer 2

Are you starting the container with docker compose up? This is working for me with hot reload at http://127.0.0.1.
version: "3.9"
services:
bff:
container_name: bff
build: .
working_dir: /code/app
command: uvicorn main:app --host 0.0.0.0 --port 8000 --reload
environment:
DEBUG: 1
volumes:
- .:/code
ports:
- "80:8000"
restart: on-failure
Also, I don't have your final two lines, if __name__ == etc., in my app. Not sure if that would change anything.

Answer 3

I found this solution that worked for me, in this answer.
In the watchfiles documentation it is understood that the detection relies on file system notifications, and I think that via docker its events are not launched when using a volume.
Notify will fall back to file polling if it can't use file system
notifications
So you have to tell watchfiles to force the polling, that's what you did in your test python script with the parameter force_polling and that's why it works:
for changes in watch('/code', force_polling=True):
Fortunately in the documentation we are given the possibility to force the polling via the environment variable WATCHFILES_FORCE_POLLING. Add this environment variable to your docker-compose.yml and auto-reload will work:
services:
fastapi-dev:
image: myimagename:${TAG:-latest}
build:
context: .
volumes:
- ./src:/code
- ./static:/static
- ./templates:/templates
restart: on-failure
ports:
- "${HTTP_PORT:-8080}:80"
environment:
- WATCHFILES_FORCE_POLLING=true