FastAPI での認証と認可に JWT トークンを使用する方法

pip install fastapi
pip install pyjwt
pip install passlib

import secrets

secret_key = secrets.token_urlsafe(32)

from pydantic import BaseModel

class User(BaseModel):
    username: str
    password: str

from fastapi import FastAPI, HTTPException
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from passlib.context import CryptContext
from datetime import datetime, timedelta
import jwt

app = FastAPI()

pwd_context = CryptContext(schemes=["bcrypt"])
security = HTTPBearer()

# 模拟数据库中的用户
users_db = {
    "admin": {
        "username": "admin",
        "password": pwd_context.hash("admin123")
    }
}

@app.post("/login")
def login(user: User):
    if user.username not in users_db:
        raise HTTPException(status_code=401, detail="Invalid username")
    
    stored_user = users_db[user.username]
    if not pwd_context.verify(user.password, stored_user["password"]):
        raise HTTPException(status_code=401, detail="Invalid password")
    
    token = generate_token(user.username)
    return {"access_token": token}

def generate_token(username: str) -> str:
    expiration = datetime.utcnow() + timedelta(minutes=30)
    payload = {"username": username, "exp": expiration}
    return jwt.encode(payload, secret_key, algorithm="HS256")

@app.get("/users/me")
def get_user_profile(credentials: HTTPAuthorizationCredentials = security):
    token = credentials.credentials
    try:
        payload = jwt.decode(token, secret_key, algorithms=["HS256"])
        username = payload["username"]
        if username not in users_db:
            raise HTTPException(status_code=401, detail="Invalid username")
        
        return {"username": username}
    except jwt.DecodeError:
        raise HTTPException(status_code=401, detail="Invalid token")

{
    "username": "admin",
    "password": "admin123"
}

{
    "access_token": "xxxxxxxxxxxxx"
}

{
    "username": "admin"
}