Each individual restaurant gets it's own cluster (we aren't fully deployed yet). There are too many network latency challenges and too much immaturity around federated clusters to take the route (unfortunately).
We currently use gitops, which houses all the configs per cluster in a single repo per restaurant (CRAZY amount of corgis!)... we call that Atlas (the repos) and we made a little pod called Vessel that polls and applies configs in those repos.
We're almost done building something called Fleet that will generated and manage those repos (Atlas) at scale. Ie; a UI where we can say "send this version to 10% of restaurants" and it will regenerate and deploy those configs to all the appropriate Atlas repos, which will then get pulled down by Vessel.
We tried doing all this with Helm but failed miserably. Maybe it was us? But templating vs gitops... the choice seemed obvious.
Other issues included; tiller would sometimes become unstable... version mismatch issues between helm local and roller... lack of a clear, outage free canary deployment... we even found cases where helm would not cleanup after itself during a deployment and retain previous config settings within k8s.
They talk about providing a service for developers to deploy stuff easily, but I'm wondering how that works in practise.
I've very little experience with Kubernetes, the author mentions they run 'mini' kubernetes clusters at each restaurant. Does that mean they have to deploy software/container updates to each restaurant one by one? Or is it abstracted above that level, where they can see ALL of the restaurants as one "big" cluster?