FastAPI Authentication & Deployment

  from datetime import datetime, timedelta, timezone
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext

SECRET_KEY = "your-secret-key-change-in-production"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

def create_access_token(data: dict, expires_delta: timedelta | None = None):
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + (expires_delta or timedelta(minutes=15))
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)

async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception
    return username

@app.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    # Verify username/password against database
    if form_data.username != "admin" or form_data.password != "secret":
        raise HTTPException(status_code=400, detail="Incorrect credentials")
    token = create_access_token(data={"sub": form_data.username})
    return {"access_token": token, "token_type": "bearer"}

@app.get("/me")
async def read_users_me(current_user: str = Depends(get_current_user)):
    return {"username": current_user}
  

  import time
from fastapi import Request

@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    start = time.perf_counter()
    response = await call_next(request)
    process_time = time.perf_counter() - start
    response.headers["X-Process-Time"] = str(process_time)
    return response
  

  from fastapi.middleware.cors import CORSMiddleware

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

  from fastapi.testclient import TestClient

client = TestClient(app)

def test_read_root():
    response = client.get("/")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello, FastAPI!"}

def test_create_item():
    response = client.post("/items/", json={"name": "Test", "price": 9.99})
    assert response.status_code == 201
  

  FROM python:3.12-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000", "--workers", "4"]