Login CRUD App (FastAPI + Streamlit)

Overview

This project provides a simple user management and login flow:

• Backend: FastAPI + SQLAlchemy, password hashing with Argon2, PostgreSQL database.
• Frontend: Streamlit login UI (Courier-based widget) to authenticate users.

The UI:

It includes user registration, login verification, and basic CRUD operations on users.

Tech Stack

• FastAPI, Uvicorn
• SQLAlchemy
• Argon2 for password hashing
• Pydantic for request/response models
• PostgreSQL (can be adapted)
• Streamlit (frontend)

Repository Layout

• backend/: FastAPI app, database models, routes, and CRUD logic
  • main.py: FastAPI application entrypoint
  • router.py: API routes (users CRUD, auth)
  • models.py: SQLAlchemy models
  • schemas.py: Pydantic schemas
  • crud.py: Database operations
  • database.py: DB connection and session
• frontend/: Streamlit app
  • app.py: Streamlit entrypoint using a login widget (src/widgets.py)
  • src/widgets.py, src/utils.py: UI and helper functions

Prerequisites

• Python 3.12
• PostgreSQL running and reachable

Setup

1. Create and activate a virtual environment (optional if you already have one):

python3.12 -m venv venv
source venv/bin/activate

2. Install dependencies (root or per service):

pip install -r requirements.txt

3. Configure backend environment variables in backend/.env:

DB_USER=your_user
DB_PASSWORD=your_password
DB_HOST=localhost
DB_PORT=5432
DB_NAME=your_database

4. Configure frontend environment for Courier in a .env (root or frontend/):

COURIER_AUTH_TOKEN=your_courier_token

Run the Backend

From the backend/ directory:

cd backend
uvicorn main:app --reload

The API will be available at http://127.0.0.1:8000.

Run the Frontend

From the project root or frontend/ directory:

streamlit run frontend/app.py

The app will prompt for login using the Courier-powered widget.

API Endpoints (selected)

• POST /auth/register: Register a new user. Body: { username, email, password, department }
• POST /auth/login: Login with { email, password } (Argon2 verification)
• GET /users: List all users
• GET /users/id/{user_id}: Get user by id
• GET /users/email/{user_email}: Get user by email
• POST /users: Create user (server-side hashing is in register flow; direct create assumes full payload)
• PUT /users/email/{user_email}: Update user fields; hashes password if present
• DELETE /users/email/{user_email}: Delete user by email
• PUT /users/email/{user_email}/password: Change password safely (Argon2)

Notes:

• Passwords are hashed with Argon2 (argon2-cffi).
• models.Users stores password (hashed), department (enum), and audit fields.

Environment and Security

• Ensure backend/.env is present; the backend will fail fast with a clear error if required variables are missing.
• Do not commit real secrets. Use .env files or secret managers for production.

Development Tips

• If you don’t need a custom port, keep DB_PORT=5432.

Docker and Docker Compose

Prerequisites

• Docker and Docker Compose installed

Environment variables

Create a .env in the project root (same folder as docker-compose.yml):

DB_USER=postgres
DB_PASSWORD=postgres
DB_HOST=db
DB_PORT=5432
DB_NAME=crud
COURIER_AUTH_TOKEN=your_courier_token

Notes:

• Backend reads DB_* envs. The compose sets DB_HOST=db (the Postgres service name).
• Frontend requires COURIER_AUTH_TOKEN. If missing, it stops with an error.

Build and run

From the project root:

docker compose up -d --build

Services and ports:

• Backend (FastAPI): http://localhost:8000
• Frontend (Streamlit): http://localhost:8510 (host port mapped to container 8501)
• Postgres: localhost:5432

###Author Lucas Inocêncio