Basic Flask Tutorial

This is a project to learn and implement basic web development in python using flask and run on localhost. This page was followed to build this tutorial: https://www.tutorialspoint.com/flask/

In this tutorial, we will learn how to run helloflask.py app written in python on a local web browser.

1. Install flask

pip3 install flask

2. Clone this repo

git clone https://github.com/nausheenfatma/basic_flask_tutorial.git

3. Run the following commands:

Goto root directory:

$ cd basic_flask_tutorial
$ python3 helloflask.py

If the command runs successfully, it should look like this:

4. Try the following URL options on the localhost on a web browser:

http://127.0.0.1:5000 prints welcome message
http://127.0.0.1:5000/hello prints hello message
http://127.0.0.1:5000/hello/nausheen prints hello message with URL variable.
Till now the messages were rendering from python return statements http://127.0.0.1:5000/hellopage renders an html pagefound in templates/hellopage.html instead of strings returned from python
http://127.0.0.1:5000/userinfo is a form to take user input and display after submit to next page
File uploads example: http://127.0.0.1:5000/upload page to upload a file.

Voila! Congratulations on learning how to run flask locally!

5. Running flask for production

Wait, we are not done yet! If you notice that running the flask app gives a warning: WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.

Check this reference docs : https://flask.palletsprojects.com/en/2.2.x/deploying/

The docs clearly mentions: After developing your application, you’ll want to make it available publicly to other users. When you’re developing locally, you’re probably using the built-in development server, debugger, and reloader. These should not be used in production. Instead, you should use a dedicated WSGI server or hosting platform.

Now there two ways:

Self hosting options
Using Hosting platforms

I chose Waitress which is a pure Python WSGI server. You may try others.

Steps :

Install waitress

pip3 install waitress

add a function create app in the python file

def create_app():
   return app

use waitress in command line to run

waitress-serve --port=8080 --call helloflask:create_app

Now check URL http://localhost:8080/hello on localhost

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