You can migrate docker deployments to K8s just by adding the parts you were missing, so when in doubt, it always makes sense to start with docker, docker-compose, and only consider K8s as an alternative to docker swarm.
In practice, I found docker to be much more brittle than kubernetes, even when kubelet uses docker underneath. K8s minimizes the amount of "features" used from docker, and unlike docker is properly designed for deployment use out of the box (and generally has cleaner architecture, so figuring out server failures tended to be easier for me with k8s than with docker daemon)
I actually spent the past 3 days attempting to migrate my DIY “docker instances managed by systemd” setup to k8s, and found getting started to be a huge pain in the ass, eventually giving up when none of the CNIs seemed to work (my 3 physical hosts could ping each other and ping all the different service addresses, but containers couldn’t ping each other’s service addresses).
That said, if anyone REALLY wants to go the k8s route, it seems like starting with vanilla docker did allow me to get 75% of the work done before I needed to touch k8s itself :)
