Schedule+

A simple webapp for Google App Engine for the students of Belarus State Economic University - parses student classes schedule from university website bseu.by and creates events in Google Calendar

Available at:

The resource is located at bseu-api.appspot.com.

Used stuff:

• Google App Engine Gen 2 with legacy bundled services
• Python 3.11.6
• Flask framework
• lxml
• leaf as lxml wrapper
• twitter bootstrap for responsive UI

Setup

You might need to download Cloud SDK and configure gcloud first:

gcloud init
gcloud auth login

NOTE if you're using macOS then the easiest way to install Google Cloud SDK is via Homebrew:

brew install google-cloud-sdk

Installing Dependencies

Create an isolated Python environment to manage application dependencies (this creates a directory in your current directory):

python3 -m venv venv

On Linux or Mac, activate the new Python environment:

source venv/bin/activate

Because you've created your virtual environment using a version of Python 3, you don't need to call python3 or pip3 explicitly. As long as your virtual environment is active, python and pip link to the same executable files that python3 and pip3 do.

python -m pip install <package-name>

As long as you don't close your terminal, every Python package that you install will end up in this isolated environment instead of your global Python site-packages.

Install dependencies listed in requirements.txt using:

python -m pip install -r requirements.txt

Once you're done working with this virtual environment, you can deactivate it:

(venv) $ deactivate

If you interact with python or pip now, you'll interact with your globally configured Python environment.

More on Python virtual environments:

• https://realpython.com/python-virtual-environments-a-primer/
• https://cloud.google.com/appengine/docs/standard/python3/building-app/writing-web-service#testing_your_web_service

Running Locally

Use dev_appserver.py from Google Cloud SDK to run the app locally, e.g.:

python3 /usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/bin/dev_appserver.py --application=bseu-api --env_var APPLICATION_ID=dev~bseu-api app.yaml

NOTE the --env_var APPLICATION_ID=dev~bseu-api param – this is necessary to open the Datastore Viewer located on admin server at http://localhost:8000/datastore.

More on running a dev server locally:

• https://cloud.google.com/appengine/docs/standard/tools/using-local-server?tab=python
• https://cloud.google.com/appengine/docs/standard/testing-and-deploying-your-app?tab=python#running_the_local_development_server_3

Setting Secrets

In order for the app to run properly, client_id and client_secret secrets need to be set.

To set them:

• start the app locally
• head over to the Datastore Viewer
• find already created corresponding GaeEnvSettings records
• and replace their values with those for the only OAuth 2.0 Client ID on the project's Google Cloud Credentials page

Debugging

Should you need to debug anything, make sure to put this line where needed:

import pdb; pdb.set_trace()

More on Python debugging:

• https://realpython.com/python-debugging-pdb/
• https://code.visualstudio.com/docs/python/debugging

Deployment:

Use gcloud instead of the deprecated appcfg to deploy the project to the App Engine server:

gcloud app deploy --project bseu-api -v 2-9-1

You might need to download Cloud SDK and configure gcloud first:

gcloud init
gcloud auth login

Update cron jobs

Any time a cron.yaml file gets modified and deployed, make sure to run the following command:

gcloud app deploy cron.yaml

To list cron jobs and see their statuses, head over to the App Engine Cron Jobs tab on Cloud Scheduler.

More info on cron jobs:

• https://cloud.google.com/appengine/docs/standard/scheduling-jobs-with-cron-yaml#uploading_cron_jobs