Flask PostgreSQL Docker CRUD API

This project is a simple RESTful API built using Flask, PostgreSQL, and Docker. It demonstrates basic CRUD (Create, Read, Update, Delete) operations for managing user data stored in a PostgreSQL database. The API is containerized using Docker for easy deployment.

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Features

• Create a User: Add a new user with a unique username and email.
• Read Users: Retrieve all users or a specific user by ID.
• Update a User: Modify the username and email of an existing user.
• Delete a User: Remove a user from the database.
• Dockerized: The entire application is containerized for seamless deployment.
• Database Integration: Uses PostgreSQL as the database backend.

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Technologies Used

• Backend: Flask (Python)
• Database: PostgreSQL
• Containerization: Docker and Docker Compose
• ORM: SQLAlchemy

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Getting Started

1. Clone the Repository

git clone <repository-url>
cd <repository-directory>

2. Environment Setup

Ensure the following environment variable is set in docker-compose.yml:

DB_URL=postgresql://postgres:postgres@flask_db:5432/postgres

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3. Build and Run the Application

Build and run the containers using Docker Compose:

docker-compose up --build

This will:

• Start a PostgreSQL database container.
• Start the Flask application container on port 4000.

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Endpoints

Base URL: http://localhost:4000

1. Test Route

• URL: /test
• Method: GET
• Description: Returns a test message to verify the API is running.
• Response:

{
  "message": "test route"
}

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2. Create a User

• URL: /users
• Method: POST
• Description: Add a new user.
• Request Body:

{
  "username": "exampleUser",
  "email": "example@example.com"
}

• Response:

{
  "message": "user created"
}

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3. Get All Users

• URL: /users
• Method: GET
• Description: Retrieve all users.
• Response:

[
  {
    "id": 1,
    "username": "exampleUser",
    "email": "example@example.com"
  }
]

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4. Get User by ID

• URL: /users/<int:id>
• Method: GET
• Description: Retrieve a specific user by their ID.
• Response:

{
  "user": {
    "id": 1,
    "username": "exampleUser",
    "email": "example@example.com"
  }
}

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5. Update a User

• URL: /users/<int:id>
• Method: PUT
• Description: Update an existing user's information.
• Request Body:

{
  "username": "updatedUser",
  "email": "updated@example.com"
}

• Response:

{
  "message": "user updated"
}

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6. Delete a User

• URL: /users/<int:id>
• Method: DELETE
• Description: Delete a user by ID.
• Response:

{
  "message": "user deleted"
}

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Running Locally (Without Docker)

1. Install Python dependencies:

   pip install -r requirements.txt

2. Set up the PostgreSQL database and update the DB_URL environment variable.

3. Run the Flask application:

   flask run --host=0.0.0.0 --port=4000

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Common Issues

• Database Connection Error: Ensure the DB_URL in docker-compose.yml is correct and matches the database service configuration.
• Port Conflict: If port 4000 or 5432 is in use, modify the docker-compose.yml file to use a different port.

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