Is there a simple way to scale Flask-SocketIO apps using a Docker Swarm deployment scheme?

[dhhagan]

What is the simplest setup for scaling Flask-SocketIO via a Docker Swarm deployment scheme?

I've read through a few of the closed issues on this forum (ex. #694, #618, #1401) and believe I understand the crux of the limitations for scaling a Flask-SocketIO deployment when using gunicorn - mostly due to lack of support for sticky sessions. I've seen your solution to scaling by starting several instances on different ports and using Nginx to load balance them. However, I was wondering if there was an approach that was easily compatible with a typical Docker Swarm deployment, where you may want to scale your SocketIO app to 3+ replicates. I've started looking through this example, and will continue to try it, but was hoping to get your/others thoughts before spending too much time in case there was something I was missing or a tutorial on the internet that I have missed.

[miguelgrinberg]

I don't use Docker swarm, so I don't know. I've made it work with Kubernetes back in the day, using a Haproxy load balancer configured with sticky sessions and a Redis for communication between the replicas.

[dhhagan]

Hey @miguelgrinberg I did end up getting this to work quite well using Traefik instead of Nginx as the reverse proxy. Do you have any recommendations on the best place to post a solution so that others can find it if needed?

[miguelgrinberg]

@dhhagan You can post it here. The added context of our discussion above will make your solution more Google/SEO friendly.

[LostInDarkMath]

@dhhagan Could you please share your solution with us? :)