In {T220235} it was decided to use plain Docker VMs for services that run on the production Kubernetes cluster. Given that the core MediaWiki application is moving to Kubernetes in the future (#mw-on-k8s) and we have more and more services that MediaWiki depends on I believe it's a good idea to at least revisit that decision.
Beta cluster currently runs some services in Docker containers dedicated VMs (`deployment-docker-*`) and a few in the legacy `deployment-sca[01-02]` cluster running Jessie and with Puppet totally broken due to production setup changes. New services are deployed and existing ones updated rarely if at all.
Resource and implementation wise I am unfortunately not sure how feasible this is. The project is almost out of Cloud VPS quota (T257118) plus setting up and maintaining a Kubernetes cluster and services running in it requires a considerable amount of time which I'm not sure who would put it into this project.
Toolforge/PAWS kubernetes clusters use HAProxy with keepalived for control plane load balancing. We could also set up prod-like LVS on beta (T196662) because that's what prod uses for kubernetes control planes (afaik, please correct if I'm wrong) and since I'd like to get LVS set up eventually that would avoid creating dedicated haproxy vms for this, even if it that would be more work to set up.