> ## Documentation Index
> Fetch the complete documentation index at: https://help.noxity.io/llms.txt
> Use this file to discover all available pages before exploring further.
# Python
> Run Python WSGI apps on cPanel via the Python Selector. Pick an alt-python version, set the entry point, manage with Pip Install.
The cPanel **Setup Python App** tool registers a Python WSGI app under your account, builds a virtualenv, and hands the running process to Phusion Passenger.
CloudLinux ships Python interpreters as `alt-python` packages. Each app picks its own version, and the virtualenv lives separate from the system Python.
## Available versions
Available versions vary by host. Typical rotation:
* **Python 3.11.** Active.
* **Python 3.10.** Maintained.
* **Python 3.9.** Older, still common for legacy apps.
Older alt-python (3.7, 3.8, 2.7) may be available for compatibility. Avoid Python 2 for anything new.
## Set up an app
From cPanel home, scroll to **Software** and click **Setup Python App**.
On an empty account, you land on a list page with a **+ Create Application** button.
* **Python version**: pick from the dropdown.
* **Application root**: directory under your home, e.g. `myapp`. Created if it doesn't exist.
* **Application URL**: domain dropdown plus optional path. Use `/` for the root or `/api` for a sub-path.
* **Application startup file**: defaults to `passenger_wsgi.py`. Leave it as that unless you have a reason.
* **Application Entry point**: dotted path plus callable, format `module:callable`. For Django: `.wsgi:application`. For Flask: `:app`.
* **Passenger log file**: optional. Useful for catching boot errors.
Click **Create**. Passenger starts the app in the background.
## Manage an app
| Button | What it does |
| ------------------- | ------------------------------------------------------------------ |
| **Run Pip Install** | Reads `requirements.txt` and installs into the per-app virtualenv. |
| **Stop App** | Halts Passenger for this app. The URL returns 503. |
| **Restart** | Equivalent to `touch tmp/restart.txt`. Reloads the running app. |
| **Edit** | Reopens the form. Saving overwrites the `.htaccess`. |
| **Destroy** | Removes Passenger registration and the per-app virtualenv. |
The **Configuration files** field accepts paths like `requirements.txt` (relative to the application root). The **Environment variables** editor sits below the buttons.
## The Passenger contract
Passenger expects a WSGI callable named `application`. Your `passenger_wsgi.py` either defines it directly or imports it from your app.
For Flask:
```python passenger_wsgi.py theme={}
from myapp import app as application
```
For Django:
```python passenger_wsgi.py theme={}
import os
import sys
sys.path.insert(0, '/home//myapp')
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myapp.settings')
from django.core.wsgi import get_wsgi_application
application = get_wsgi_application()
```
Your code does not run a development server. No `app.run()`, no `manage.py runserver`.
Calling `app.run()` (Flask) or `runserver` (Django) inside a Passenger-managed app makes Passenger see no `application` and return a 500 with `passenger_wsgi.py did not provide an "application" callable`. Remove the call.
## ASGI apps
Native ASGI (FastAPI, Starlette, Channels) needs a WSGI shim. The common bridge is `asgiref.WsgiToAsgi` reversed, but Passenger's WSGI mode does not handle WebSockets or HTTP/2 streaming over ASGI. For a sync FastAPI subset, wrap with `a2wsgi`:
```python passenger_wsgi.py theme={}
from a2wsgi import ASGIMiddleware
from main import app as asgi_app
application = ASGIMiddleware(asgi_app)
```
For real WebSockets, run Daphne or Uvicorn outside the Selector. {/* TODO: write a Power-plan recipe for ASGI on a dedicated port */}
## Reference: where things live
| What | Path |
| ------------------------ | ------------------------------------------------ |
| Activated env script | `~/virtualenv///bin/activate` |
| Installed packages | `~/virtualenv///lib/...` |
| Restart trigger | `~//tmp/restart.txt` |
| Passenger config | `~//.htaccess` (Selector-managed) |
| Boot log (if configured) | path you set in **Passenger log file** |
From SSH, activate manually:
```bash theme={}
source ~/virtualenv/myapp/3.11/bin/activate && cd ~/myapp
pip install -r requirements.txt
```
## Common issues
`passenger_wsgi.py` doesn't expose a top-level name `application`. Either rename your callable to `application`, or alias it: `application = app`.
The package was installed against the system Python, not the per-app virtualenv. Run **Pip Install** from the cPanel UI, or activate the env in SSH first: `source ~/virtualenv///bin/activate`.
Passenger only serves the WSGI app. Run `manage.py collectstatic` and serve `/static/` directly from Apache. Add to `.htaccess`:
```apache theme={}
Alias /static/ /home//myapp/static/
/myapp/static">
Require all granted
```
PMEM is \~1 GB. Heavy compiled wheels can OOM. Use prebuilt wheels (the default for pandas / numpy on linux x86\_64), avoid `--no-binary`, and consider installing one package at a time.
Default Passenger startup timeout is 60 seconds. Long migrations or heavy `INSTALLED_APPS` initialization can exceed it. Bump the timeout in `.htaccess`:
```apache theme={}
PassengerStartTimeout 120
```
## Recipes
Django app, virtualenv, static files.
Flask service via `passenger_wsgi.py`.
## Need a hand?
Best for anything that needs an account check or a config change on our end.
Faster for quick questions during business hours.
* [Virtual Containers overview](/web-hosting/virtual-containers/overview)
* [Setup Python App ↗](https://docs.cpanel.net/cpanel/software/setup-python-app/)
* [CloudLinux Python Selector ↗](https://docs.cloudlinux.com/cloudlinuxos/cloudlinux_os_components/#python-selector)
* [Phusion Passenger Python ↗](https://www.phusionpassenger.com/library/walkthroughs/start/python.html)