Build a Python Web Server with Flask

Install Flask

• Open the Terminal
• Enter the command pip3 install flask

• Make a new directory named webapp using the Terminal command mkdir webapp
• Enter the new directory with the command cd webapp

First web application =

• Open up Thonny.
• Paste the following code into Thonny.
• Save the file as app.py in the webapp directory.

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello world'

if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')

Run Flask from Terminal

• Open the Terminal
• To run the app.py program enter the command python3 app.py from within the /home/pi/webapp directory
• You should see a similar response.

• Now open your web browser and enter the following URL https://127.0.0.1:5000/
• You should see this response.