On Thu, May 28, 2020 at 12:24:22AM +0000, Eric Wheeler wrote: > On Mon, 15 Oct 2018, Nir Soffer wrote: > > On Sat, Oct 13, 2018 at 9:45 PM Eric Wheeler <n...@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).
So this bit is simple, and something we do regularly. Assuming the "remote VM" is using qemu as a hypervisor, then qemu has a curl driver integrated so you can mount remote http:// or https:// resources as disks on the VM directly. eg: $ qemu-system-x86_64 -m 2048 -cdrom https://download.fedoraproject.org/pub/fedora/linux/releases/32/Server/x86_64/iso/Fedora-Server-dvd-x86_64-32-1.6.iso (A more realistic example would use libvirt, see the https protocol in: https://libvirt.org/formatdomain.html#elementsDisks ) You can also bounce the connection through nbdkit-curl-plugin which gives you a bit more flexibility, eg the ability to transparently uncompress the remote ISO. You would be using the NBD client in qemu to connect (eg. over a Unix domain socket) to a local nbdkit, and nbdkit's curl plugin to connect to the remote ISO. More info and a worked example in these pages: http://libguestfs.org/nbdkit-curl-plugin.1.html https://rwmj.wordpress.com/2018/11/23/nbdkit-xz-curl/ > This is common for remote KVM (iDRAC/iLO/iKVM/CIMC), so wondering about > an http front-end for qemu to do the same. I'm a bit confused by what you mean by "http front-end for qemu". > Combining that with a spice JS client or noVNC for VM console access would > be neat. These are separate issues. qemu has a VNC or SPICE client built in for the console. > I also like Eric Blake's idea of direct NBD client integration with qemu > instead of using /dev/nbd0. You shouldn't need to use a loop device for this scenario, assuming I've understood what you want. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v _______________________________________________ Libguestfs mailing list Libguestfs@redhat.com https://www.redhat.com/mailman/listinfo/libguestfs
