niqzart/flask-socketio-example

Short example of a minimal flask-socketio application, that actually works. No compatibility errors, no too old libraries. Config for heroku is in the repo as well.

Flask SocketIO Example

Why?

I haven't found a good described example for that. Ones I found are either too old and use old versions of used libraries (which is not ideal) or don't work because of a version compatibility issue(s). I managed to make it work, but it did take a few hours.

I hope this example will help someone to not waste the same amount of time.

What does it do?

It's a python web server that serves an HTML page with a chat-like interface. You can send messages, which are processed by flask-soketio and broadcasted to everyone connected to the main page.

The example is hosted on heroku, you can visit it and try it out for yourself here. Open up two tabs with it and chat!

A bit on how I will try to make this example future-proof

1. All requirements are marked as exact versions, so version compatibility shouldn't become a problem
2. I'm still working on an app with flask-socketio, this repo will be updated from time to time (last update date == last commit date)
3. If some links go dead, I'll replace them, you can report such links in issues

What should be redone for production environment?

CORS policy. Currently it's allowing any origins, that should never be a thing in a production environment. See flask-socketio documentation for info on CORS configuration

Hot to run it locally?

1. Clone the repo
2. Create a virtual python environment (https://docs.python.org/3/library/venv.html)
3. Open a console & activate the virtual environment
4. Install requirements: pip install -r requirements.txt
5. Run the main file: python main.py
6. Done! Web server should be running at http://localhost:5000/

How to deploy this to heroku?

1. Clone the repo
2. Open a console in repo's folder
3. Create an application on heroku
4. Login to heroku CLI: heroku login
5. Attach your heroku app as a git remote: heroku git:remote -a your-app-name-here
6. Push it to heroku: git push heroku master
7. Wait for it to deploy, when visit your applications page, and you're done!

Links

• Why an older version of eventlet is used:

  • https://stackoverflow.com/questions/67409452/gunicorn-importerror-cannot-import-name-already-handled-from-eventlet-wsgi

• Deployment of flask-socketio applications:

  • https://flask-socketio.readthedocs.io/en/latest/deployment.html

• Client configuration:

  • https://socket.io/docs/v4/client-installation/#standalone-build