Hands-on Flask-02 : Handling Routes and Templates with Flask Web Application

Purpose of the this hands-on training is to give the students introductory knowledge of how to handle routes and use html templates within a Flask web application on Amazon Linux 2 EC2 instance.

Learning Outcomes

At the end of the hands-on training, students will be able to;

install Python and Flask framework on Amazon Linux 2 EC2 instance
build a simple web application with Flask framework.
understand the HTTP request-response cycle and structure of URL.
create routes (or views) with Flask.
serve static content and files using Flask.
serve dynamic content using the html templates.
write html templates using Jinja Templating Engine.

Outline

Part 1 - Getting to know routing and HTTP URLs.
Part 2 - Install Python and Flask framework Amazon Linux 2 EC2 Instance
Part 3 - Write a Web Application with Sample Routings and Templating on GitHub Repo
Part 4 - Run the Web App on EC2 Instance

Part 1 - Getting to know routing and HTTP URLs.

HTTP (Hypertext Transfer Protocol) is a request-response protocol. A client on one side (web browser) asks or requests something from a server and the server on the other side sends a response to that client. When we open our browser and write down the URL (Uniform Resource Locator), we are requesting a resource from a server and the URL is the address of that resource. The structure of typical URL is as the following.

The server responds to that request with an HTTP response message. Within the response, a status code element is a 3-digit integer defines the category of response as shown below.

1xx -> Informational
2xx -> Success
3xx -> Redirection
4xx -> Client Error
5xx -> Server Error

Part 2 - Install Python and Flask framework Amazon Linux 2 EC2 Instance

Launch an Amazon EC2 instance using the Amazon Linux 2 AMI with security group allowing SSH (Port 22) and HTTP (Port 80) connections.
Connect to your instance with SSH.
Update the installed packages and package cache on your instance.
Install Python 3 packages.
Check the python3 version
Install Python 3 Flask framework.
Check the versions of Flask framework packages (flask, click, itsdangerous, jinja2, markupSafe, werkzeug)

Part 3 - Write a Web Application with Sample Routings and Templating on GitHub Repo

Create folder named flask-02-handling-routes-and-templates-on-ec2-linux2 within clarusway-python-workshop repo
Create python file named app.py
Write an application with routing and templating samples and save the complete code under hands-on/flask-02-handling-routes-and-templates-on-ec2-linux2 folder.

#Import Flask modules

#Create an object named app 

# Create a function named home which returns a string 'This is home page for no path, <h1> Welcome Home</h1>' 
# and assign route of no path ('/')

# Create a function named about which returns a formatted string '<h1>This is my about page </h1>' 
# and assign to the static route of ('about')

# Create a function named error which returns a formatted string '<h1>Either you encountered an error or you are not authorized.</h1>' 
# and assign to the static route of ('error')

# Create a function named hello which returns a string of '<h1>Hello, World! </h1>' 
# and assign to the static route of ('/hello')

# Create a function named admin which redirect the request to the error path 
# and assign to the route of ('/admin')

# Create a function named greet which return formatted inline html string 
# and assign to the dynamic route of ('/<name>')

# Create a function named greet_admin which redirect the request to the hello path with param of 'Master Admin!!!!' 
# and assign to the route of ('/greet-admin')

# Rewrite a function named greet which which uses template file named `greet.html` under `templates` folder 
# and assign to the dynamic route of ('/<name>')

# Create a function named list10 which creates a list counting from 1 to 10 within `list10.html` 
# and assign to the route of ('/list10')

Create a function named evens which show the even numbers from 1 to 10 within `evens.html` 
and assign to the route of ('/evens')

# Add a statement to run the Flask application which can be reached from any host on port 80.

Write a template html file named greet.html which takes name as parameter under templates folder
Write a template html file named list10.html which shows a list counting from 1 to 10 under templates folder
Write a template html file named evens.html which shows a list of even numbers from 1 to 10 under templates folder
Create a folder named static under hands-on/flask-02-handling-routes-and-templates-on-ec2-linux2 folder and create a text file named mytext.txt with This is a text file in static folder content.
Add and commit all changes on local repo
Push app.py, greet.html, list10.html, evens.html, and mytext.txt to remote repo clarusway-python-workshop on GitHub.

Part 4 - Run the Hello World App on EC2 Instance

Download the web application file from GitHub repo.
Run the web application
Connect the route handling and templating web application from the web browser and try every routes configured
Open the static file mytext.txt context from the web browser
Connect the route handling and templating web application from the terminal with curl command.