Implement user authentication service with FastAPI

- Set up project structure and dependencies
- Create SQLAlchemy database models
- Set up Alembic for database migrations
- Implement user registration and login endpoints
- Add JWT token authentication
- Create middleware for protected routes
- Add health check endpoint
- Update README with documentation

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,85 @@
-# FastAPI Application
+# User Authentication Service
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A FastAPI-based service for user authentication and management.
+
+## Features
+
+- User registration and account management
+- Secure password handling with bcrypt hashing
+- JWT-based authentication
+- Protected API endpoints
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+
+## Project Structure
+
+```
+├── alembic/                  # Database migration files
+│   └── versions/             # Migration version files
+├── app/                      # Application code
+│   ├── middleware/           # Middleware components
+│   ├── models/               # SQLAlchemy models
+│   ├── routers/              # API routes
+│   ├── utils/                # Utility functions
+│   ├── database.py           # Database connection setup
+│   ├── models.py             # SQLAlchemy models
+│   └── schemas.py            # Pydantic schemas
+├── alembic.ini               # Alembic configuration
+├── main.py                   # Application entry point
+└── requirements.txt          # Project dependencies
+```
+
+## API Endpoints
+
+### Authentication
+
+- `POST /auth/token` - OAuth2 token endpoint (form-based)
+- `POST /auth/login` - Login endpoint (JSON-based)
+
+### Users
+
+- `POST /users/` - Register a new user
+- `GET /users/me` - Get current user information
+- `GET /users/` - Get list of users
+- `GET /users/{user_id}` - Get a specific user by ID
+
+### Health Check
+
+- `GET /health` - Health check endpoint
+
+## Installation
+
+1. Clone the repository
+2. Install dependencies:
+   ```
+   pip install -r requirements.txt
+   ```
+
+3. Run the application:
+   ```
+   uvicorn main:app --reload
+   ```
+
+4. Access the API documentation at `http://localhost:8000/docs`
+
+## Database
+
+The application uses SQLite as the database with SQLAlchemy ORM. Database migrations are managed with Alembic.
+
+### Creating a Migration
+
+```bash
+alembic revision --autogenerate -m "description"
+```
+
+### Running Migrations
+
+```bash
+alembic upgrade head
+```
+
+## Security
+
+- Passwords are hashed using bcrypt
+- Authentication is handled using JWT tokens
+- Protected routes require a valid JWT token

alembic.ini

@@ -0,0 +1,84 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = alembic
+
+# template used to generate migration files
+# file_template = %%(rev)s_%%(slug)s
+
+# timezone to use when rendering the date
+# within the migration file as well as the filename.
+# string value is passed to dateutil.tz.gettz()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; this defaults
+# to alembic/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path
+# version_locations = %(here)s/bar %(here)s/bat alembic/versions
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks=black
+# black.type=console_scripts
+# black.entrypoint=black
+# black.options=-l 79
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = INFO
+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/README

@@ -0,0 +1 @@
+Generic single-database configuration with an async engine.

alembic/env.py

@@ -0,0 +1,82 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+import sys
+import os
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+from app.models import Base
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    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():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    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():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

alembic/versions/34cbb67a51c3_create_users_table.py

@@ -0,0 +1,39 @@
+"""create users table
+
+Revision ID: 34cbb67a51c3
+Revises: 
+Create Date: 2025-05-13 00:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '34cbb67a51c3'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table('users',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('email', sa.String(), nullable=True),
+        sa.Column('username', sa.String(), nullable=True),
+        sa.Column('hashed_password', sa.String(), nullable=True),
+        sa.Column('is_active', sa.Boolean(), nullable=True, default=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)
+    op.create_index(op.f('ix_users_username'), 'users', ['username'], unique=True)
+
+
+def downgrade():
+    op.drop_index(op.f('ix_users_username'), table_name='users')
+    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/__init__.py

@@ -0,0 +1 @@
+# This file is intentionally left empty to mark the directory as a Python package

app/database.py

@@ -0,0 +1,31 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+from pathlib import Path
+
+# Create database directory
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+# Database URL
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+# Create SQLAlchemy engine
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+# Create SessionLocal class
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+# Create Base class
+Base = declarative_base()
+
+# Dependency
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/middleware/__init__.py

@@ -0,0 +1 @@
+# This file is intentionally left empty to mark the directory as a Python package

app/middleware/jwt_middleware.py

@@ -0,0 +1,83 @@
+from fastapi import Request, HTTPException, status
+from fastapi.responses import JSONResponse
+from app.utils.auth import decode_token
+from app.database import SessionLocal
+from app.models import User
+from starlette.datastructures import Headers
+import re
+
+
+PUBLIC_PATHS = [
+    r'^/docs$',
+    r'^/redoc$',
+    r'^/openapi.json$',
+    r'^/auth/token$',
+    r'^/auth/login$',
+    r'^/users/$',
+    r'^/health$',
+]
+
+
+async def get_current_user(token: str):
+    """
+    Get the current user from a JWT token
+    """
+    payload = decode_token(token)
+    
+    db = SessionLocal()
+    try:
+        user = db.query(User).filter(User.username == payload["username"]).first()
+        if user is None:
+            raise HTTPException(status_code=404, detail="User not found")
+        return user
+    finally:
+        db.close()
+
+
+async def verify_token(request: Request, call_next):
+    """
+    Middleware to verify JWT tokens
+    """
+    # Check if the path is public
+    path = request.url.path
+    for pattern in PUBLIC_PATHS:
+        if re.match(pattern, path):
+            return await call_next(request)
+    
+    # Get the Authorization header
+    auth_header = request.headers.get("Authorization")
+    if not auth_header:
+        return JSONResponse(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            content={"detail": "Not authenticated"},
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    # Extract the token
+    try:
+        scheme, token = auth_header.split()
+        if scheme.lower() != "bearer":
+            return JSONResponse(
+                status_code=status.HTTP_401_UNAUTHORIZED,
+                content={"detail": "Invalid authentication scheme"},
+                headers={"WWW-Authenticate": "Bearer"},
+            )
+    except ValueError:
+        return JSONResponse(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            content={"detail": "Invalid token format"},
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    # Verify the token and get the current user
+    try:
+        user = await get_current_user(token)
+        # Add the user to the request state
+        request.state.user = user
+        return await call_next(request)
+    except HTTPException as e:
+        return JSONResponse(
+            status_code=e.status_code,
+            content={"detail": e.detail},
+            headers=e.headers,
+        )

app/models.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Boolean, Column, Integer, String, DateTime
+from sqlalchemy.sql import func
+from app.database import Base
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    email = Column(String, unique=True, index=True)
+    username = Column(String, unique=True, index=True)
+    hashed_password = Column(String)
+    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/__init__.py

@@ -0,0 +1 @@
+# This file is intentionally left empty to mark the directory as a Python package

app/routers/auth.py

@@ -0,0 +1,85 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
+from sqlalchemy.orm import Session
+from datetime import timedelta
+from app import models, schemas
+from app.database import get_db
+from app.utils.auth import (
+    verify_password,
+    create_access_token,
+    ACCESS_TOKEN_EXPIRE_MINUTES,
+)
+
+router = APIRouter(
+    prefix="/auth",
+    tags=["authentication"],
+    responses={401: {"description": "Unauthorized"}},
+)
+
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="auth/token")
+
+
+def authenticate_user(username: str, password: str, db: Session):
+    """
+    Authenticate a user with username and password
+    """
+    user = db.query(models.User).filter(models.User.username == username).first()
+    
+    if not user:
+        return False
+    
+    if not verify_password(password, user.hashed_password):
+        return False
+    
+    return user
+
+
+@router.post("/token", response_model=schemas.Token)
+async def login_for_access_token(
+    form_data: OAuth2PasswordRequestForm = Depends(),
+    db: Session = Depends(get_db)
+):
+    """
+    OAuth2 compatible token login, returns an access token
+    """
+    user = authenticate_user(form_data.username, form_data.password, db)
+    
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect username or password",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    access_token = create_access_token(
+        data={"sub": user.username, "user_id": user.id},
+        expires_delta=access_token_expires,
+    )
+    
+    return {"access_token": access_token, "token_type": "bearer"}
+
+
+@router.post("/login", response_model=schemas.Token)
+async def login(
+    login_data: schemas.LoginRequest,
+    db: Session = Depends(get_db)
+):
+    """
+    Regular login endpoint, returns an access token
+    """
+    user = authenticate_user(login_data.username, login_data.password, db)
+    
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect username or password",
+        )
+    
+    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    access_token = create_access_token(
+        data={"sub": user.username, "user_id": user.id},
+        expires_delta=access_token_expires,
+    )
+    
+    return {"access_token": access_token, "token_type": "bearer"}

app/routers/users.py

@@ -0,0 +1,76 @@
+from fastapi import APIRouter, Depends, HTTPException, status, Request
+from sqlalchemy.orm import Session
+from app import models, schemas
+from app.database import get_db
+from app.utils.auth import get_password_hash
+from typing import List
+
+router = APIRouter(
+    prefix="/users",
+    tags=["users"],
+    responses={404: {"description": "Not found"}},
+)
+
+
+@router.post("/", response_model=schemas.UserResponse, status_code=status.HTTP_201_CREATED)
+def create_user(user: schemas.UserCreate, db: Session = Depends(get_db)):
+    """
+    Register a new user
+    """
+    # Check if username exists
+    db_user_by_username = db.query(models.User).filter(models.User.username == user.username).first()
+    if db_user_by_username:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Username already registered"
+        )
+    
+    # Check if email exists
+    db_user_by_email = db.query(models.User).filter(models.User.email == user.email).first()
+    if db_user_by_email:
+        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 = models.User(
+        email=user.email,
+        username=user.username,
+        hashed_password=hashed_password
+    )
+    
+    db.add(db_user)
+    db.commit()
+    db.refresh(db_user)
+    
+    return db_user
+
+
+@router.get("/me", response_model=schemas.UserResponse)
+def read_users_me(request: Request):
+    """
+    Get current user information
+    """
+    return request.state.user
+
+
+@router.get("/", response_model=List[schemas.UserResponse])
+def read_users(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    """
+    Get list of users
+    """
+    users = db.query(models.User).offset(skip).limit(limit).all()
+    return users
+
+
+@router.get("/{user_id}", response_model=schemas.UserResponse)
+def read_user(user_id: int, db: Session = Depends(get_db)):
+    """
+    Get a specific user by ID
+    """
+    db_user = db.query(models.User).filter(models.User.id == user_id).first()
+    if db_user is None:
+        raise HTTPException(status_code=404, detail="User not found")
+    return db_user

app/schemas.py

@@ -0,0 +1,37 @@
+from pydantic import BaseModel, EmailStr, Field
+from typing import Optional
+from datetime import datetime
+
+
+class UserBase(BaseModel):
+    email: EmailStr
+    username: str
+
+
+class UserCreate(UserBase):
+    password: str = Field(..., min_length=8)
+
+
+class UserResponse(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):
+    username: Optional[str] = None
+    user_id: Optional[int] = None
+
+
+class LoginRequest(BaseModel):
+    username: str
+    password: str

app/utils/__init__.py

@@ -0,0 +1 @@
+# This file is intentionally left empty to mark the directory as a Python package

app/utils/auth.py

@@ -0,0 +1,62 @@
+from datetime import datetime, timedelta
+from typing import Optional
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+from fastapi import HTTPException, status
+
+# JWT settings
+SECRET_KEY = "YOUR_SECRET_KEY"  # In production, use a secure environment variable
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_MINUTES = 30
+
+# Password context for hashing
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+
+def verify_password(plain_password, hashed_password):
+    """Verify a password against a hash"""
+    return pwd_context.verify(plain_password, hashed_password)
+
+
+def get_password_hash(password):
+    """Generate a hash from a password"""
+    return pwd_context.hash(password)
+
+
+def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
+    """Create a JWT access token"""
+    to_encode = data.copy()
+    
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    
+    to_encode.update({"exp": expire})
+    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
+    
+    return encoded_jwt
+
+
+def decode_token(token: str):
+    """Decode and validate a JWT token"""
+    try:
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        username = payload.get("sub")
+        user_id = payload.get("user_id")
+        
+        if username is None:
+            raise HTTPException(
+                status_code=status.HTTP_401_UNAUTHORIZED,
+                detail="Invalid authentication credentials",
+                headers={"WWW-Authenticate": "Bearer"},
+            )
+        
+        return {"username": username, "user_id": user_id}
+    
+    except JWTError:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Invalid authentication credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        )

main.py

@@ -0,0 +1,34 @@
+from fastapi import FastAPI
+from app import models
+from app.database import engine
+from app.routers import auth, users
+from app.middleware import jwt_middleware
+from pathlib import Path
+
+# Create database tables
+models.Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title="User Authentication Service",
+    description="A service for user authentication and management",
+    version="0.1.0",
+)
+
+# Add middleware
+app.middleware("http")(jwt_middleware.verify_token)
+
+# Include routers
+app.include_router(auth.router)
+app.include_router(users.router)
+
+@app.get("/health", tags=["Health"])
+async def health_check():
+    """
+    Health check endpoint that returns the service status
+    """
+    return {"status": "healthy"}
+
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

requirements.txt

@@ -0,0 +1,9 @@
+fastapi==0.105.0
+uvicorn==0.24.0
+sqlalchemy==2.0.23
+alembic==1.12.1
+pydantic==2.5.2
+python-jose==3.3.0
+passlib==1.7.4
+python-multipart==0.0.6
+bcrypt==4.0.1