Flask Quickstart

Overview

Flask is a Python microframework for building web sites with minimal overhead. Think of it as a lightweight version of Django with fewer features, but better speed. Flask is supported on v6+ platforms using Passenger.

Quickstart

All steps are done from the terminal. While it may be possible to deploy a Flask application without using terminal, it is strongly recommended for ease.

1. Prerequisite: create a Passenger-compatible filesystem layout
2. Change directories to the base, we’ll name the base directory flask in /var/www
   • cd /var/www/flask
3. Optional: determine which Python version to use for Flask using pyenv
4. Install flask using pip:

   • pip install flask

5. Create a Passenger startup file to run Flask as a Python WSGI application:

   • from flask import Flask
     application = Flask(__name__)
      
     @application.route("/")
     def hello():
      return "Hello World!"
     
     if __name__ == "__main__":
      application.run()

   • Of importance, this example is identical to the Flask “Hello World!” example with a minor change: app is renamed to application to comply with Passenger. Passenger will always look for an instance variable named application to run the application.
6. Connect public/ to a subdomain within the control panel under Web > Subdomains
7. Access your subdomain running Flask

Restarting a Flask app

Since Flask runs using Passenger, it uses the same restart method as any Passenger-backed app.

See also

• Explore Flask eBook
• Flask documentation
• Django vs Flask vs Pyramid
• Flask demo running on a v6 account