[flaminHotSpeedo]

Containers are never a security boundary. If you configure them correctly, avoid all the footguns, and pray that there's no container escape vulnerabilities that affect "correctly" configured containers then they can be a crude approximation of a security boundary that may be enough for your use case, but they aren't a suitable substitute for hardware backed virtualization.

The only serious company that I'm aware of which doesn't understand that is Microsoft, and the reason I know that is because they've been embarrassed again and again by vulnerabilities that only exist because they run multitenant systems with only containers for isolation

[vel0city]

Virtual machines are never a security boundary. If you configure them correctly, avoid all the footguns, and pray that there's no VM escape vulnerabilities that affect "correctly" configured VMs then they can be a crude approximation of a security boundary that may be enough for your use case, but they aren't a suitable substitute for entirely separate hardware.

Its all turtles, all the way down.

[flaminHotSpeedo]

Yeah, in some (rare) situations physical isolation is a more appropriate level of security. Or if you want to land somewhere in between, you can use VM's with single tenant NUMA nodes.

But for a typical case, VM's are the bare minimum to say you have a _secure_ isolation boundary because the attack surface is way smaller.