Implement user authentication flow with FastAPI

- Set up FastAPI application with SQLite database
- Create User model with email and password fields
- Implement JWT token-based authentication
- Add user registration and login endpoints
- Create protected user profile endpoints
- Configure Alembic for database migrations
- Add password hashing with bcrypt
- Include CORS middleware and health endpoint
- Update README with setup and usage instructions

Environment variables required:
- SECRET_KEY: JWT secret key for token signing

README.md

@@ -1,3 +1,78 @@
-# FastAPI Application
+# User Authentication Service
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A FastAPI-based user authentication service with JWT token authentication and SQLite database.
+
+## Features
+
+- User registration and login
+- JWT token-based authentication
+- Password hashing with bcrypt
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- CORS enabled for all origins
+- Health check endpoint
+- Auto-generated API documentation
+
+## Environment Variables
+
+Set the following environment variables before running the application:
+
+- `SECRET_KEY`: JWT secret key for token signing (required for production)
+
+## Installation
+
+1. Install dependencies:
+```bash
+pip install -r requirements.txt
+```
+
+2. Run database migrations:
+```bash
+alembic upgrade head
+```
+
+3. Start the application:
+```bash
+uvicorn main:app --reload
+```
+
+## API Endpoints
+
+### Public Endpoints
+- `GET /` - Service information
+- `GET /health` - Health check
+- `POST /api/v1/auth/register` - User registration
+- `POST /api/v1/auth/login` - User login
+
+### Protected Endpoints (require Bearer token)
+- `GET /api/v1/users/me` - Get current user info
+- `GET /api/v1/users/profile` - Get user profile
+
+## API Documentation
+
+Once the application is running, visit:
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+- OpenAPI JSON: http://localhost:8000/openapi.json
+
+## Usage Example
+
+1. Register a new user:
+```bash
+curl -X POST "http://localhost:8000/api/v1/auth/register" \
+     -H "Content-Type: application/json" \
+     -d '{"email": "user@example.com", "password": "password123"}'
+```
+
+2. Login to get access token:
+```bash
+curl -X POST "http://localhost:8000/api/v1/auth/login" \
+     -H "Content-Type: application/x-www-form-urlencoded" \
+     -d "username=user@example.com&password=password123"
+```
+
+3. Access protected endpoint:
+```bash
+curl -X GET "http://localhost:8000/api/v1/users/me" \
+     -H "Authorization: Bearer YOUR_ACCESS_TOKEN"
+```

alembic.ini

@@ -0,0 +1,41 @@
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+version_path_separator = os
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+
+[post_write_hooks]
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

alembic/env.py

@@ -0,0 +1,49 @@
+from logging.config import fileConfig
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+from alembic import context
+import sys
+import os
+
+sys.path.append(os.path.dirname(os.path.dirname(__file__)))
+
+from app.db.base import Base
+
+config = context.config
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+def run_migrations_offline() -> None:
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+def run_migrations_online() -> None:
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, target_metadata=target_metadata
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

alembic/script.py.mako

@@ -0,0 +1,22 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

alembic/versions/001_create_users_table.py

@@ -0,0 +1,33 @@
+"""create users table
+
+Revision ID: 001
+Revises: 
+Create Date: 2024-01-01 00:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = '001'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+def upgrade() -> None:
+    op.create_table('users',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('email', sa.String(), nullable=False),
+        sa.Column('hashed_password', sa.String(), nullable=False),
+        sa.Column('is_active', sa.Boolean(), nullable=True),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=True),
+        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_users_email'), 'users', ['email'], unique=True)
+    op.create_index(op.f('ix_users_id'), 'users', ['id'], unique=False)
+
+def downgrade() -> None:
+    op.drop_index(op.f('ix_users_id'), table_name='users')
+    op.drop_index(op.f('ix_users_email'), table_name='users')
+    op.drop_table('users')

app/api/routes/auth.py

@@ -0,0 +1,87 @@
+from datetime import timedelta
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
+from sqlalchemy.orm import Session
+from jose import JWTError, jwt
+
+from app.core.security import (
+    ALGORITHM,
+    SECRET_KEY,
+    create_access_token,
+    get_password_hash,
+    verify_password,
+)
+from app.db.session import get_db
+from app.models.user import User
+from app.schemas.user import Token, TokenData, UserCreate, User as UserSchema
+
+router = APIRouter()
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="api/v1/auth/login")
+
+def get_user_by_email(db: Session, email: str):
+    return db.query(User).filter(User.email == email).first()
+
+def authenticate_user(db: Session, email: str, password: str):
+    user = get_user_by_email(db, email)
+    if not user:
+        return False
+    if not verify_password(password, user.hashed_password):
+        return False
+    return user
+
+def create_user(db: Session, user: UserCreate):
+    hashed_password = get_password_hash(user.password)
+    db_user = User(
+        email=user.email,
+        hashed_password=hashed_password
+    )
+    db.add(db_user)
+    db.commit()
+    db.refresh(db_user)
+    return db_user
+
+async def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)):
+    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])
+        email: str = payload.get("sub")
+        if email is None:
+            raise credentials_exception
+        token_data = TokenData(email=email)
+    except JWTError:
+        raise credentials_exception
+    user = get_user_by_email(db, email=token_data.email)
+    if user is None:
+        raise credentials_exception
+    return user
+
+async def get_current_active_user(current_user: User = Depends(get_current_user)):
+    if not current_user.is_active:
+        raise HTTPException(status_code=400, detail="Inactive user")
+    return current_user
+
+@router.post("/register", response_model=UserSchema)
+def register(user: UserCreate, db: Session = Depends(get_db)):
+    db_user = get_user_by_email(db, email=user.email)
+    if db_user:
+        raise HTTPException(status_code=400, detail="Email already registered")
+    return create_user(db=db, user=user)
+
+@router.post("/login", response_model=Token)
+def login_for_access_token(form_data: OAuth2PasswordRequestForm = Depends(), db: Session = Depends(get_db)):
+    user = authenticate_user(db, form_data.username, form_data.password)
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    access_token_expires = timedelta(minutes=30)
+    access_token = create_access_token(
+        subject=user.email, expires_delta=access_token_expires
+    )
+    return {"access_token": access_token, "token_type": "bearer"}

app/api/routes/users.py

@@ -0,0 +1,15 @@
+from fastapi import APIRouter, Depends
+
+from app.api.routes.auth import get_current_active_user
+from app.models.user import User
+from app.schemas.user import User as UserSchema
+
+router = APIRouter()
+
+@router.get("/me", response_model=UserSchema)
+def read_users_me(current_user: User = Depends(get_current_active_user)):
+    return current_user
+
+@router.get("/profile", response_model=UserSchema)
+def get_user_profile(current_user: User = Depends(get_current_active_user)):
+    return current_user

app/core/security.py

@@ -0,0 +1,30 @@
+import os
+from datetime import datetime, timedelta
+from typing import Any, Union
+from passlib.context import CryptContext
+from jose import jwt
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+SECRET_KEY = os.getenv("SECRET_KEY", "your-secret-key-change-this-in-production")
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_MINUTES = 30
+
+def create_access_token(
+    subject: Union[str, Any], expires_delta: timedelta = None
+) -> str:
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(
+            minutes=ACCESS_TOKEN_EXPIRE_MINUTES
+        )
+    to_encode = {"exp": expire, "sub": str(subject)}
+    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
+    return encoded_jwt
+
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    return pwd_context.verify(plain_password, hashed_password)
+
+def get_password_hash(password: str) -> str:
+    return pwd_context.hash(password)

app/db/base.py

@@ -0,0 +1,3 @@
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()

app/db/session.py

@@ -0,0 +1,22 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+DB_DIR = Path("/app/storage/db")
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/user.py

@@ -0,0 +1,13 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+from app.db.base import Base
+
+class User(Base):
+    __tablename__ = "users"
+    
+    id = Column(Integer, primary_key=True, index=True)
+    email = Column(String, unique=True, index=True, nullable=False)
+    hashed_password = Column(String, nullable=False)
+    is_active = Column(Boolean, default=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

app/schemas/user.py

@@ -0,0 +1,29 @@
+from pydantic import BaseModel, EmailStr
+from typing import Optional
+from datetime import datetime
+
+class UserBase(BaseModel):
+    email: EmailStr
+
+class UserCreate(UserBase):
+    password: str
+
+class UserLogin(BaseModel):
+    email: EmailStr
+    password: str
+
+class User(UserBase):
+    id: int
+    is_active: bool
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+    
+    class Config:
+        from_attributes = True
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str
+
+class TokenData(BaseModel):
+    email: Optional[str] = None

main.py

@@ -0,0 +1,41 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from app.api.routes import auth, users
+from app.db.session import engine
+from app.db.base import Base
+
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title="User Authentication Service",
+    description="A FastAPI service for user authentication",
+    version="1.0.0",
+    openapi_url="/openapi.json"
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(auth.router, prefix="/api/v1/auth", tags=["authentication"])
+app.include_router(users.router, prefix="/api/v1/users", tags=["users"])
+
+@app.get("/")
+async def root():
+    return {
+        "title": "User Authentication Service",
+        "documentation": "/docs",
+        "health": "/health"
+    }
+
+@app.get("/health")
+async def health_check():
+    return {
+        "status": "healthy",
+        "service": "User Authentication Service",
+        "version": "1.0.0"
+    }

requirements.txt

@@ -0,0 +1,8 @@
+fastapi==0.104.1
+uvicorn==0.24.0
+sqlalchemy==2.0.23
+alembic==1.13.0
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+python-multipart==0.0.6
+ruff==0.1.6