Hi,

It does not run a full guest OS on the hypervisor, instead, initrd itself launches a group of docker images, aka Pod on it.

I like what you've done with Pod. Remember rkt has a similar concept, not sure why Docker doesn't have it.

So you're running all the containers on the initrd kernel?

I had the same question, and had to dig a little into the Google Pod documentation for this handy explanation: "In terms of Docker constructs, a pod consists of a colocated group of Docker containers with shared volumes."[1]

Based on the above tidbit, each Pod contains a few containers, thus a Pod (and hence all of the containers in the Pod) will indeed be running on the initrd kernel from the HyperVM instance.

The key point is that this applies for each HyperVM (i.e. one HyperVM launched per Pod). It seems the idea is that wherever you'd normally launch a container, you can now instead launch a lighweight VM that behaves like a container (i.e. fast to launch & small footprint) with default virtualization benefits.

Basically, if you replace all instances of the term "HyperVM" with "ContainerVM", it may help to parse their explanations more easily.

[1] https://github.com/GoogleCloudPlatform/kubernetes/blob/maste...

A pod on a kernel/initrd, contains one or more docker images in different mount namespaces. The "containers" in pod share network and ipc namespace each other.