Swarm might be great, but the ecosystem around k8s is massive. So my two choices are: ignore Docker entirely and do it like I've always done (Heroku, chef, puppet, etc. just managing my servers myself), or buy into containers and go with K8S.
To that extent, I only ever deal with K8S at work, and for my personal stuff I don't go near Docker at all. Why would I when I can get an 8GB/4CPU VPS for $9/mo and serve everything I care about from that? I've got fail2ban, systemd, caddy, and plenty of resources.
I can host mysql on the same machine because there isn't a god-given law about hosting your DB on a separate box. Same with anything else.
No need for Docker or Swarm or K8s.