fastapi-lightauth 0.1.0

A lightweight JWT authentication library for FastAPI and SQLAlchemy.

fastapi-lightauth

A lightweight JWT authentication library for FastAPI and SQLAlchemy. Built with simplicity in mind for small and medium FastAPI projects.

Features:

• JWT authentication
• Secure password hashing with bcrypt
• User registration and login endpoints
• Current-user dependency injection
• Extendable SQLAlchemy user models
• Extendable Pydantic schemas
• Async SQLAlchemy support

Installation

pip install fastapi-lightauth

---

Quick start

1. Define your user model

LightAuth requires 'UserMixin', but everything else is completely up to you

from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
from lightauth import UserMixin


class Base(DeclarativeBase):
  pass


class User(UserMixin, Base):
  __tablename__ = "users"

  extra_stuff: Mapped[str] = mapped_column(default="no extra stuff here")

---

2. Optional: extend your response schema

You can add fields that you want returned in API responses:

from lightauth.schemas import UserReadBase


class UserReadSchema(UserReadBase):
  extra_stuff: str

---

3. Create a session dependency

from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from typing import AsyncGenerator, Any

engine = create_async_engine("sqlite+aiosqlite:///:memory:")
session_maker = async_sessionmaker(engine)


async def get_session() -> AsyncGenerator[AsyncSession, Any]:
    async with session_maker() as session:
        yield session

---

4. Set up LightAuth

from lightauth import LightAuth

auth = LightAuth[User](
  secret="your-secret-key",
  model=User,
  get_session=get_session,
)

Optionally configure token lifespan via token_lifespan_days

---

5. Add the router

from lightauth import get_auth_router
from lightauth.schemas import UserCreateBase

app.include_router(
  get_auth_router(
    auth,
    UserReadSchema,
    UserCreateBase,
  )
)

---

Using authentication in routes

You protect routes using a FastAPI dependency:

from fastapi import Depends

@app.get("/hello")
async def hello(user: User = Depends(auth.current_user)):
    return f"Hello, {user.username}"

That dependency will:

• read the Bearer token
• validate the JWT
• load the user from the database
• inject the full SQLAlchemy user object

---

Endpoints

Register

POST /auth/register

{
  "username": "...",
  "password": "..."
}

Returns the created user.

---

Login

POST /auth/login

{
  "username": "...",
  "password": "..."
}

Returns:

{
  "access_token": "eyJ...",
  "token_type": "Bearer"
}

---

Current user

GET /auth/me

Requires:

Authorization: Bearer <token>

Returns the current user.

---

Security notes

• Passwords are hashed using bcrypt
• JWT tokens include:
  • sub → user ID
  • exp → expiration timestamp
• Default token lifetime: 30 days

---

License

MIT