Open Stack

> Thanks for the concern and fully under it , the major reason is
> cloud-init doesn't have a hook or plugin before it start to read
> config drive (ISO disk) z/VM is an old hypervisor and no way to do
> something like libvirt to define a ISO format disk in xml definition,
> instead, it can define disks in the defintion of virtual machine and
> let VM to decide its format.
>
> so we need a way to tell cloud-init where to find ISO file before
> cloud-init start but without AE, we can't handle that...some update on
> the spec here for further information
> https://review.openstack.org/#/c/562154/

The ISO format does not come from telling libvirt something about
it. The host creates and formats the image, adds the data, and then
attaches it to the instance. The latter part is the only step that
involves configuring libvirt to attach the image to the instance. The
rest is just stuff done by nova-compute (and the virt driver) on the
linux system it's running on. That's the same arrangement as your
driver, AFAICT.

You're asking the system to hypervisor (or something running on it) to
grab the image from glance, pre-filled with data. This is no different,
except that the configdrive image comes from the system running the
compute service. I don't see how it's any different in actual hypervisor
mechanics, and thus feel like there _has_ to be a way to do this without
the AE magic agent.

I agree with Mikal that needing more agent behavior than cloud-init does
a disservice to the users.

I feel like we get a lot of "but no, my hypervisor is special!"
reasoning when people go to add a driver to nova. So far, I think
they're a lot more similar than people think. Ironic is the weirdest one
we have (IMHO and no offense to the ironic folks) and it can support
configdrive properly.

--Dan