[Libguestfs] Provide NBD via Browser over Websockets

[Eric Wheeler]

On Mon, 15 Oct 2018, Nir Soffer wrote:
> On Sat, Oct 13, 2018 at 9:45 PM Eric Wheeler <nbd at lists.ewheeler.net> wrote:
>       Hello all,
> 
>       It might be neat to attach ISOs to KVM guests via websockets.  Basically
>       the  browser would be the NBD "server" and an NBD client would run on the
>       hypervisor, then use `virsh change-media vm1 hdc --insert /dev/nbd0` could
>       use an ISO from my desk to boot from.
> 
>       Here's an HTML5 open file example:
>       https://stackoverflow.com/questions/3582671/how-to-open-a-local-disk-file-with-javascript
> 
>       and the NBD protocol looks simple enough to implement in javascript:
>       https://stackoverflow.com/questions/17295140/where-is-the-network-block-device-format-describled
> 
>       What do you think? Does anyone have an interest in doing this?
> 
> 
> HTML File API is very limited:
> - you cannot access any file except file provided by the user interactively
> - no support for sparseness or underlying disk block size
> 
> So it will be a pretty bad backend for NBD server.
> 
> What are you trying to do?

Hi Nir and Eric,

I hope you are well!  

(I'm resurecting this old thread, not sure how I missed the replies.)

We are interested in attaching a local ISO to a remote VM over http (maybe 
.qcow's, but ISO is the primary interest).

This is common for remote KVM (iDRAC/iLO/iKVM/CIMC), so wondering about 
an http front-end for qemu to do the same.

Combining that with a spice JS client or noVNC for VM console access would 
be neat.

I also like Eric Blake's idea of direct NBD client integration with qemu 
instead of using /dev/nbd0.

-Eric

> 
> Nir
> 
>