# Deploying Flask on cPanel with Passenger

This guide demonstrates how to deploy a Flask application on a cPanel hosting environment using **Phusion Passenger**. Many modern cPanel hosts use Passenger to manage Python (and Node.js/Ruby) applications, making deployment relatively straightforward compared to traditional CGI.

## Prerequisites

1.  **cPanel Hosting**: Your hosting provider must support "Setup Python App" (CloudLinux/Passenger).
2.  **Access**: Access to cPanel and File Manager (or SSH).

## Step 1: Create Python App in cPanel

1.  Log in to **cPanel**.
2.  Find the **Software** section and click **Setup Python App**.
3.  Click **Create Application**.
4.  **Python Version**: Select a recommended version (e.g., 3.9 or newer).
5.  **Application Root**: The folder where your app files will live (e.g., `myapp`).
6.  **Application URL**: The domain or path where the app will be accessible (e.g., `mydomain.com/app`).
7.  **Application Startup File**: Leave blank or set to `passenger_wsgi.py`.
8.  **Application Entry Point**: Leave blank or set to `application`.
9.  Click **Create**.

cPanel will create the directory and a virtual environment. It usually gives you a command to enter the virtual environment (e.g., `source /home/user/virtualenv/myapp/3.9/bin/activate`).

## Step 2: The Flask Application

Create a file named `app.py` inside your **Application Root** folder (e.g., `myapp`).

```python
from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
    return "Hello from Flask on cPanel!"

if __name__ == "__main__":
    app.run()
```

## Step 3: The Passenger Entry Point

Passenger looks for a file named `passenger_wsgi.py`. This file tells the server how to run your app. Create or edit `passenger_wsgi.py` in your **Application Root**.

```python
import sys
import os

# 1. Add the current directory to sys.path so Python can find your app
sys.path.insert(0, os.path.dirname(__file__))

# 2. Import the Flask app
# 'from app' refers to app.py
# 'import app as application' is crucial because Passenger looks for an object named 'application'
from app import app as application
```

## Step 4: Install Dependencies

1.  Create a `requirements.txt` file in your **Application Root**:
    ```text
    Flask
    ```

2.  **Install via cPanel UI**:
    *   Go back to **Setup Python App** in cPanel.
    *   Click **Edit** on your app.
    *   Scroll down to "Configuration files", enter `requirements.txt`, and click **Add**.
    *   Click **Run Pip Install**.

## Step 5: Restart the Application

Whenever you make changes to the code, you must restart the app for Passenger to reload it.

1.  Go to **Setup Python App** in cPanel.
2.  Click the **Restart** button next to your application.

Visit your URL, and you should see "Hello from Flask on cPanel!".

[[programming/python/python]]