If you want to run a Dev Container directly using only the Dockerfile, without the need for a `devcontainer.json` file, here’s how you can do it:

### Step 1: Install Dev Containers Extension in VS Code

Make sure you have the **Dev Containers** extension installed in Visual Studio Code.

### Step 2: Create Your `Dockerfile`

You already have a `Dockerfile` in place. For reference, here’s the basic one you provided:

```Dockerfile
# Dockerfile
FROM python:3.12-slim

WORKDIR /app

COPY . /app

CMD ["python", "app.py"]
```

Make sure that your `Dockerfile` is in the root of your project.

### Step 3: Open VSCode and Attach to Container

Once your Dockerfile is ready, follow these steps:

1. Open your project in VSCode.
2. Press `Ctrl+Shift+P` and type `Dev Containers: Open Folder in Container...`.
3. Choose the folder containing your `Dockerfile`.
4. VSCode will automatically detect the `Dockerfile` and build the development container based on it.

### Step 4: Run Your Application Inside the Dev Container

Once the container is built and your environment is set up:

- Open the integrated terminal (`Ctrl+` `).
- Run the Python application using:

```bash
python app.py
```

You should see the output `Hello, World!`.

### Benefits of Using the Dockerfile Directly

By doing this, you're directly using the Dockerfile to spin up your development environment inside a container. You get the benefits of containerized development without needing to write a `devcontainer.json` configuration file. This is useful when you want a minimal setup.

