Flask Web Deployment on Google Cloud

Follow the project here Convert Schedule to .ics, we will going to edit the app.py (main.py)

source code here

Python Script Development

Here is a little bit different from regular app. Most of time we have a landing page under root (/) but since my script is a POST method which is a callable page. It cannot be used to independently. Thus we choose to load the index.html first at root page.

Your main.py file is set up to deploy a web application using Flask, a popular micro web framework in Python. Let's break down this file step by step:

Importing Libraries and Modules

from flask import Flask, request, send_file
from flask_cors import CORS
import io
import datetime
import cal_web  # Import your cal_web script

• Flask: The main class in Flask; it is used to create your application.
• request: To handle incoming requests to your server.
• send_file: A Flask utility to send files as responses.
• CORS: A Flask extension that handles Cross-Origin Resource Sharing (CORS), making cross-origin AJAX possible.
• io: For in-memory file operations.
• datetime: For handling date and time.
• cal_web: This is your script that contains the logic for parsing input and creating calendar files.

Setting Up the Flask App

app = Flask(__name__)
CORS(app)

• Initializes a new Flask application.
• Enables CORS for this application.

Routing

Index Route

@app.route('/')
def index():
    return app.send_static_file('index.html')

• The decorator @app.route('/') tells Flask to execute this function when the root URL is accessed.
• Returns the index.html file. This is likely the entry point of your web application's frontend.

Generate ICS Route

@app.route('/generate-ics', methods=['POST'])
def generate_ics():
    ...

• This route handles the generation of .ics files.
• It's set to respond to POST requests to /generate-ics.

Handling POST Request to Generate ICS

1. Extracting Data from Request:

   • data = request.json gets the JSON data sent with the POST request.
   • Extracts startDate, endDate, and schedule from the JSON data.

2. Converting Dates:

   • Converts startDate and endDate from string to datetime objects.
   • If the conversion fails, it returns a 400 error with an "Invalid date input" message.

3. Generating ICS File:

   • Uses cal_web.parse_input to parse the schedule text.
   • cal_web.parse_and_create_ics_files is then used to create a ZIP file containing the .ics files.

4. Sending the ZIP File as a Response:

   • The ZIP data is converted to a file-like object using io.BytesIO.
   • send_file is used to send this file as a response to the client, with appropriate headers to prompt a file download.

Running the App

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

• This condition ensures that the server is run only if this script is executed directly (not imported as a module).
• app.run(debug=True) starts the Flask application with debug mode enabled. Debug mode provides a reloader and debugger.

Summary

In summary, this script sets up a Flask web server with two endpoints: one for serving the index.html file and another for handling POST requests to generate .ics files from a given schedule. The script integrates with the cal_web module you've previously written to handle the calendar-related logic. The use of CORS allows for cross-origin requests, making it suitable for a modern web application setup.

.yaml edit

Usually editing in this way

runtime: python39  # Specify the Python version
entrypoint: gunicorn -b :$PORT main:app  # Replace 'main' with the name of your Python file without '.py'

Next use html Script HTML Template