Implement complete user authentication system with FastAPI

- Set up FastAPI application with CORS and proper structure
- Created User model with SQLAlchemy and SQLite database
- Implemented JWT-based authentication with bcrypt password hashing
- Added user registration, login, and profile endpoints
- Created health check endpoint for monitoring
- Set up Alembic for database migrations
- Added comprehensive API documentation
- Configured proper project structure with separate modules
- Updated README with complete setup and usage instructions

README.md

@@ -1,3 +1,64 @@
-# 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 support.
+
+## Features
+
+- User registration and login
+- JWT token-based authentication
+- Password hashing with bcrypt
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- Health check endpoint
+- CORS enabled for all origins
+- API documentation available at `/docs` and `/redoc`
+
+## Environment Variables
+
+The following environment variables should be set:
+
+- `SECRET_KEY`: JWT secret key for token signing (defaults to "your-secret-key-change-in-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
+
+### Base
+- `GET /` - Service information
+- `GET /health` - Health check
+
+### Authentication
+- `POST /auth/register` - Register a new user
+- `POST /auth/login` - Login user
+- `POST /auth/token` - OAuth2 compatible token endpoint
+- `GET /auth/me` - Get current user info (requires authentication)
+- `POST /auth/logout` - Logout user
+
+## Database Structure
+
+The application uses SQLite with the following user table structure:
+- `id`: Primary key
+- `email`: Unique user email
+- `hashed_password`: Bcrypt hashed password
+- `is_active`: User status flag
+- `created_at`: Account creation timestamp
+- `updated_at`: Last update timestamp
+
+## Development
+
+The project uses Ruff for code formatting and linting.

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 +1,50 @@
+from logging.config import fileConfig
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+from alembic import context
+import os
+import sys
+
+# Add the project root directory to Python path
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__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 +1,24 @@
+"""${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 +1,35 @@
+"""Create users table
+
+Revision ID: 001
+Revises: 
+Create Date: 2024-01-01 12:00:00.000000
+
+"""
+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/core/security.py

@@ -0,0 +1,37 @@
+from datetime import datetime, timedelta
+from typing import Optional
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+import os
+
+SECRET_KEY = os.getenv("SECRET_KEY", "your-secret-key-change-in-production")
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_MINUTES = 30
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+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)
+
+def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
+    to_encode = data.copy()
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(minutes=15)
+    to_encode.update({"exp": expire})
+    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
+    return encoded_jwt
+
+def verify_token(token: str):
+    try:
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        email: str = payload.get("sub")
+        if email is None:
+            return None
+        return email
+    except JWTError:
+        return None

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 sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from pathlib import Path
+
+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, DateTime, Boolean
+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/routers/auth.py

@@ -0,0 +1,91 @@
+from datetime import timedelta
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordRequestForm
+from sqlalchemy.orm import Session
+from app.db.session import get_db
+from app.models.user import User
+from app.schemas.user import UserCreate, UserResponse, UserLogin, Token
+from app.core.security import verify_password, get_password_hash, create_access_token, ACCESS_TOKEN_EXPIRE_MINUTES
+from app.utils.auth import get_current_active_user
+
+router = APIRouter()
+
+@router.post("/register", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
+async def register_user(user: UserCreate, db: Session = Depends(get_db)):
+    # Check if user already exists
+    db_user = db.query(User).filter(User.email == user.email).first()
+    if db_user:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Email already registered"
+        )
+    
+    # Create new user
+    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
+
+@router.post("/login", response_model=Token)
+async def login_user(user_credentials: UserLogin, db: Session = Depends(get_db)):
+    user = db.query(User).filter(User.email == user_credentials.email).first()
+    
+    if not user or not verify_password(user_credentials.password, user.hashed_password):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    if not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Inactive user"
+        )
+    
+    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    access_token = create_access_token(
+        data={"sub": user.email}, expires_delta=access_token_expires
+    )
+    return {"access_token": access_token, "token_type": "bearer"}
+
+@router.post("/token", response_model=Token)
+async def login_for_access_token(
+    form_data: OAuth2PasswordRequestForm = Depends(),
+    db: Session = Depends(get_db)
+):
+    user = db.query(User).filter(User.email == form_data.username).first()
+    
+    if not user or not verify_password(form_data.password, user.hashed_password):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    if not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Inactive user"
+        )
+    
+    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    access_token = create_access_token(
+        data={"sub": user.email}, expires_delta=access_token_expires
+    )
+    return {"access_token": access_token, "token_type": "bearer"}
+
+@router.get("/me", response_model=UserResponse)
+async def read_users_me(current_user: User = Depends(get_current_active_user)):
+    return current_user
+
+@router.post("/logout")
+async def logout_user():
+    # In a stateless JWT system, logout is handled client-side by discarding the token
+    return {"message": "Successfully logged out"}

app/routers/health.py

@@ -0,0 +1,23 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+from sqlalchemy import text
+from app.db.session import get_db
+import datetime
+
+router = APIRouter()
+
+@router.get("/health")
+async def health_check(db: Session = Depends(get_db)):
+    try:
+        # Test database connection
+        db.execute(text("SELECT 1"))
+        db_status = "healthy"
+    except Exception as e:
+        db_status = f"unhealthy: {str(e)}"
+    
+    return {
+        "status": "healthy" if db_status == "healthy" else "unhealthy",
+        "timestamp": datetime.datetime.utcnow().isoformat(),
+        "database": db_status,
+        "service": "User Authentication Service"
+    }

app/schemas/user.py

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

app/utils/auth.py

@@ -0,0 +1,34 @@
+from fastapi import Depends, HTTPException, status
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
+from sqlalchemy.orm import Session
+from app.db.session import get_db
+from app.models.user import User
+from app.core.security import verify_token
+
+security = HTTPBearer()
+
+def get_current_user(
+    credentials: HTTPAuthorizationCredentials = Depends(security),
+    db: Session = Depends(get_db)
+) -> User:
+    credentials_exception = HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Could not validate credentials",
+        headers={"WWW-Authenticate": "Bearer"},
+    )
+    
+    token = credentials.credentials
+    email = verify_token(token)
+    if email is None:
+        raise credentials_exception
+    
+    user = db.query(User).filter(User.email == email).first()
+    if user is None:
+        raise credentials_exception
+    
+    return user
+
+def get_current_active_user(current_user: User = Depends(get_current_user)) -> User:
+    if not current_user.is_active:
+        raise HTTPException(status_code=400, detail="Inactive user")
+    return current_user

main.py

@@ -0,0 +1,38 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from app.routers import auth, health
+from app.db.session import engine
+from app.db.base import Base
+
+# Create tables
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title="User Authentication Service",
+    description="A FastAPI service for user authentication",
+    version="1.0.0",
+    docs_url="/docs",
+    redoc_url="/redoc",
+    openapi_url="/openapi.json"
+)
+
+# CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(auth.router, prefix="/auth", tags=["authentication"])
+app.include_router(health.router, tags=["health"])
+
+@app.get("/")
+async def root():
+    return {
+        "title": "User Authentication Service",
+        "documentation": "/docs",
+        "health": "/health"
+    }

requirements.txt

@@ -0,0 +1,9 @@
+fastapi==0.104.1
+uvicorn[standard]==0.24.0
+sqlalchemy==2.0.23
+alembic==1.12.1
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+python-multipart==0.0.6
+pydantic[email]==2.5.0
+ruff==0.1.7