Re: [RFC DOCUMENT 00/12] kubevirt-and-kvm: Add documents

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Andrea,

On 9/16/20 6:44 PM, Andrea Bolognani wrote:
> Hello there!
> 
> Several weeks ago, a group of Red Hatters working on the
> virtualization stack (primarily QEMU and libvirt) started a
> conversation with developers from the KubeVirt project with the goal
> of better understanding and documenting the interactions between the
> two.
> 
> Specifically, we were interested in integration pain points, with the
> underlying ideas being that only once those issues are understood it
> becomes possible to look for solutions, and that better communication
> would naturally lead to improvements on both sides.
> 
> This series of documents was born out of that conversation. We're
> sharing them with the QEMU and libvirt communities in the hope that
> they can be a valuable resource for understanding how the projects
> they're working on are consumed by higher-level tools, and what
> challenges are encountered in the process.
> 
> Note that, while the documents describe a number of potential
> directions for things like development of new components, that's all
> just brainstorming that naturally occurred as we were learning new
> things: the actual design process should, and will, happen on the
> upstream lists.
> 
> Right now the documents live in their own little git repository[1],
> but the expectation is that eventually they will find a suitable
> long-term home. The most likely candidate right now is the main
> KubeVirt repository, but if you have other locations in mind please
> do speak up!
> 
> I'm also aware of the fact that this delivery mechanism is fairly
> unconventional, but I thought it would be the best way to spark a
> discussion around these topics with the QEMU and libvirt developers.
> 
> Last but not least, please keep in mind that the documents are a work
> in progress, and polish has been applied to them unevenly: while the
> information presented is, to the best of our knowledge, all accurate,
> some parts are in a rougher state than others. Improvements will
> hopefully come over time - and if you feel like helping out in making
> that happen, it would certainly be appreciated!
> 
> Looking forward to your feedback :)
> 
> 
> [1] https://gitlab.com/abologna/kubevirt-and-kvm

Thanks a lot for this documentation, I could learn new things,
use cases out of my interest area. Useful as a developer to
better understand how are used the areas I'm coding. This
shorten a bit that gap between developers and users.

What would be more valuable than a developer review/feedback is
having feedback from users and technical writers.
Suggestion: also share it on qemu-discuss@nongnu.org which is
less technical (maybe simply repost the cover and link to the
Wiki).

--

What is not obvious in this cover (and the documents pasted on
the list) is there are schema pictures on the Wiki pages which
are not viewable and appreciable via an email post.

--

I had zero knowledge on Kubernetes. I have been confused by their
use in the introduction...

From Index:

"The intended audience is people who are familiar with the traditional
virtualization stack (QEMU plus libvirt), and in order to make it
more approachable to them comparisons, are included and little to no
knowledge of KubeVirt or Kubernetes is assumed."

Then in Architecture's {Goals and Components} there is an assumption
Kubernetes is known. Entering in Components, Kubernetes is briefly
but enough explained.

Then KubeVirt is very well explained.

--

Sometimes the "Other topics" category is confusing, it seems out
of the scope of the "better understanding and documenting the
interactions between KubeVirt and KVM" and looks like left over
notes. I.e.:

"Another possibility is to leverage the device-mapper from Linux to
provide features such as snapshots and even like Incremental Backup.
For example, dm-era seems to provide the basic primitives for
bitmap tracking.
This could be part of scenario number 1, or cascaded with other PVs
somewhere else.
Is this already being used? For example, cybozu-go/topolvm is a
CSI LVM Plugin for k8s."

"vhost-user-blk in other CSI backends
Would it make sense for other CSI backends to implement support for
vhost-user-blk?"

"The audience is people who are familiar with the traditional
virtualization stack (QEMU plus libvirt)". Feeling part of the
audience, I have no clue how to answer these questions...
I'd prefer you tell me :)

Maybe renaming the "Other topics" section would help.
"Unanswered questions", "Other possibilities to investigate",...

--

Very good contribution in documentation,

Thanks!

Phil.