Being a big fan of containerisation for many reasons, for me, the default open-networking is the biggest footgun of the lot. Docker Swarm seems to be better for

Being a big fan of containerisation for many reasons, for me, the default open-networking is the biggest footgun of the lot. Docker Swarm seems to be better for treating networks as principle objects whereas K8S requires that you install custom network drivers, otherwise you only seem to get namespaces for protection (i.e. no protection) within a cluster. For me also, the tooling to actually see what is happening at the network level, what DNS has been assigned, what can and can't route is not easy to identify even though I understand a reasonable amount about the theory. Even an obvious question like, "if we are sharing a registry between development and production clusters, does that introduce a vulnerability?" doesn't have an obvious answer. VLANs are great but again, they don't seem to exist in K8S by default and we already read that Docker was punching its own holes in firewalls anyway. Maybe the default for all of these orchestrators should be private networks unless you specifically open them up otherwise I can see why people might recommend running DB servers on VMs with more obvious attack surfaces.