Re: [atomic-devel] Running VMs in Openshift

[Colin Walters <walters verbum org>]

On Thu, Mar 30, 2017, at 03:04 PM, Stef Walter wrote:
> After starting a VM in kubevirt, can access the qemu monitor or have
> libvirt access to that VM ... from a container in a kubernetes pod?

To rephrase what Stef is saying:

First, this is mostly about using VMs for *testing*.  Not running
production VMs.  For example, in this model, it's a *good* thing
if the spawned VMs cannot see (network-wise) any other VMs that happen to
live in the same infrastructure.

I've seen many, *many* variations of test frameworks which
provision VMs in libvirt/OpenStack/AWS etc.  and ssh in from
the place where the test framework is executing (a Jenkins instance,
or whatever, most commonly a different VM in the same infrastructure).

One problem with this approach is "lifecycle binding".  If the
executor process dies, the VM leaks.  Now obviously there are
many fixes for this - configure the VM to die after idle for an hour,
scan for old VMs and delete them, etc.

But with the model of having the test code and the qemu process colocated,
they naturally die together.

Second, this also obviously greatly reduces latency - there's no *reason*
the test execution code should be on a separate physical machine from
the target VM(s).

And third, this model allows low-level access to qemu which is
quite useful when doing OS testing.