add a python starter tutorial too

source/tutorials/tutorials-passenger-apps.rst

@@ -12,4 +12,5 @@ At the bottom of the page is a list of tutorials for developing Passenger apps f
    :caption: Tutorials
 
    tutorials-passenger-apps/ps-to-quota
-   tutorials-passenger-apps/nodejs-starter-app
+   tutorials-passenger-apps/nodejs-starter-app
+   tutorials-passenger-apps/python-starter-app

source/tutorials/tutorials-passenger-apps/nodejs-starter-app.rst

@@ -81,7 +81,6 @@ string.
 Boot the application
 --------------------
 
-
 Now that the app's all setup and implemented, you should be able to
 boot it up.  To do so, simply navigate to ``My Sandbox Apps (Development)``
 in the ``Develop`` menu of your OnDemand installation.

source/tutorials/tutorials-passenger-apps/python-starter-app.rst

@@ -0,0 +1,142 @@
+.. _app-development-tutorials-python:
+
+Starter Python Application
+==========================
+
+
+This document describes how to start a Passenger application
+in `Python`_ language.
+
+Basic application
+-----------------
+
+``passenger_wsgi.py`` is the entrypoint for any python application.
+
+.. code:: shell
+
+  cd ~/ondemand/dev
+  mkdir python-hello-world
+  cd python-hello-world
+  touch passenger_wsgi.py
+
+Now with the ``passenger_wsgi.py`` file created, we can add this content to
+serve a response to a request.
+
+.. code:: python
+
+  # passenger_wsgi.py 
+  import sys
+
+  def application(environ, start_response):
+      start_response('200 OK', [('Content-type', 'text/plain')])
+      return ["Hello World from Open OnDemand (Python WSGI)!\n\n" + sys.version]
+
+Boot the application
+--------------------
+
+Now that the app's all setup and implemented, you should be able to
+boot it up.  To do so, simply navigate to ``My Sandbox Apps (Development)``
+in the ``Develop`` menu of your OnDemand installation.
+
+There you should see this application at the top of the list.  Clicking
+``Launch Python Hello World`` will launch this application in a new tab.
+
+When the new tab opens you should see a blank page with the text ``Hello World``
+with some extra text about the system. This is your new `Python`_ application!
+
+
+Application using Flask and a virtual environment
+-------------------------------------------------
+
+The basic application above is fine, but you'll likely need to add
+more dependencies and load those dependencies at runtime.
+
+So this section goes over adding the `Flask`_ web framework and having
+the application load the virtual environment that has your dependencies in
+it.
+
+Create the virtual environmet
+`````````````````````````````
+
+First, we need to create the virtual environment. Issue this command below
+to create one. This will create a subdirectory ``python-hello-world`` with a
+``bin/activate`` file you can use to activate the environment.
+
+.. code:: shell
+
+  python3 -m venv python-hello-world
+
+Now, let's create the ``requriements.txt`` file where we'll add the application's
+required libraries. Here, we're only adding ``flask`` of any version.
+
+.. code:: text
+
+  # requirements.txt
+  flask
+
+.. code:: shell
+
+  source python-hello-world/bin/activate
+  python3 -m pip install -r requirements.txt
+
+Create the python files
+```````````````````````
+
+In the basic example above, the entire implementation is held within a ``passenger_wsgi.py``.
+This project is more advanced, so it will include two files. ``passenger_wsgi.py`` and
+``app.py``.  ``app.py`` will hold the logic for the application.
+
+``passenger_wsgi.py`` simply imports the app from the ``app.py`` file. This is all that's required
+for this file.
+
+.. code:: python
+
+  # passenger_wsgi.py
+  from app import MyApp as application
+
+``app.py`` on the other hand, has logic associcated with the web application in it.
+It imports the `Flask`_ libraries, configures the routes and starts the flask server.
+
+.. code:: python
+
+  # app.py
+  from flask import Flask
+  import sys
+
+  MyApp = Flask('python_hello_world')
+
+  @MyApp.route("/")
+  def index():
+    return 'Hello World!<br>' + sys.version
+
+  if __name__ == "__main__":
+    MyApp.run()
+
+Using the virtual environment
+`````````````````````````````
+
+At this point, the app is basically done, but won't boot up because it
+can't find `Flask`_ libraries. We created a virtual environment in a previous
+step, now we have to get OnDemand to recognize this environment.
+
+To do this, we need to create a `bin/python` wrapper file to load the appropriate
+virtual environment.
+
+.. code:: shell
+
+  #!/usr/bin/env bash
+
+  SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+  source $SCRIPT_DIR/../python-hello-world/bin/activate
+
+  exec /bin/env python3 "$@"
+
+.. warning::
+  Ensure that this ``bin/python`` file has executable permissons on it.
+  Issue the command ``chmod +x bin.python`` to give it executable permissions.
+
+Now, with the python wrapper script to load the environment for your application,
+it should boot up correctly.
+
+.. _Python: https://www.python.org/
+.. _Flask: https://flask.palletsprojects.com/en/3.0.x/