On Mon, Jul 9, 2018 at 8:06 PM Richard W.M. Jones <rjo...@redhat.com> wrote:
> On Mon, Jul 09, 2018 at 07:02:50PM +0200, Kevin Wolf wrote: > > Am 09.07.2018 um 18:52 hat Richard W.M. Jones geschrieben: > > > On Mon, Jul 09, 2018 at 07:38:05PM +0300, Nir Soffer wrote: > > > > We are discussing importing VM images to KubVirt. The goal is to be > > > > able to import an existing qcow2 disk, probably some appliance stored > > > > on http server, and and convert it to raw format for writing to > storage. > > > > > > > > This can be also useful for for oVirt for importing OVA, since we > like to > > > > pack > > > > disks in qcow2 format inside OVA, but the user may like to use raw > disks, or > > > > for uploading existing disks. > > > > > > > > Of course converting the image using qemu-img is easy, but requires > > > > downloading the image to temporary disk. We would like to avoid > temporary > > > > disks, or telling users to convert the image. > > > > > > > > Base on the discussion we had here: > > > > > https://lists.ovirt.org/archives/list/us...@ovirt.org/thread/GNAVJ253FP65QUSOONES5XZGRIDX5ABC/#YMLSEGU7PN3MX5MUORGEGGAQLLSL4KKJ > > > > > > > > I think this is impossible since qcow2 is not built for streaming. > But both > > > > Richard and Eric suggested some solutions. > > > > > > > > The flow is: > > > > > > > > qcow2 image -- http --> importer -> raw file > > > > > > > > Is it possible to implement the importer using qemu-img and qemu-nbd, > > > > or maybe nbdkit? > > > > > > Strictly speaking streaming qcow2 to raw is not possible. However > > > placing an overlay on top of the original remote image will allow > > > streaming to raw with only a modest amount of local storage consumed. > > > > > > You can demonstrate this fairly easily: > > > > > > $ qemu-img create -f qcow2 -b 'json: { "file.driver": "https", > "file.url": " > https://uk-mirrors.evowise.com/fedora/releases/28/Cloud/x86_64/images/Fedora-Cloud-Base-28-1.1.x86_64.qcow2", > "file.timeout": 10000 }' /var/tmp/overlay.qcow2 > > > $ qemu-img convert -p -f qcow2 -O raw overlay.qcow2 fedora.img > > > > This overlay stays empty, so it's pretty pointless and you could just > > directly point 'qemu-img convert' to https and the real image. > > Right, indeed. I was copying what virt-v2v does without thinking > about it enough. virt-v2v needs the overlay because it actually wants > to write into it, and it does copy-on-read for the first phase (not > the final ‘qemu-img convert’). > Thanks, I just tested the simple: qemu-img convert -p -f qcow2 -O raw http://localhost/orig.qcow2 converted.raw And it just works :-) I got timeouts trying to download from https://download.fedoraproject.org/pub/alt/atomic/stable/Fedora-Atomic-28-20180625.1/AtomicHost/x86_64/images/Fedora-AtomicHost-28-20180625.1.x86_64.qcow2 I guess we need to use 'json: { "file.driver": "http", "file.url": "url...", "file.timeout": 10000 }' To change timeout? Where is these and other options documented? I did also some timings, using sever on local network with 1g nic. $ time wget http://local.server/Fedora-AtomicHost-28-20180625.1.x86_64.qcow2 ... Length: 638043136 (608M) [application/octet-stream]Saving to: ‘Fedora-AtomicHost-28-20180625.1.x86_64.qcow2’ Fedora-AtomicHost-28-20180625.1.x86_64.qcow2 100%[=====================================================================================================>] 608.49M 107MB/s in 5.6s 2018-07-09 21:38:39 (108 MB/s) - ‘Fedora-AtomicHost-28-20180625.1.x86_64.qcow2’ saved [638043136/638043136] real 0m5.941s user 0m0.183s sys 0m1.185s $ time qemu-img convert -p -f qcow2 -O raw http://local.server/Fedora-AtomicHost-28-20180625.1.x86_64.qcow2 converted.raw (100.00/100%) real 0m14.217s user 0m5.235s sys 0m2.343s $ time qemu-img convert -p -f qcow2 -O raw Fedora-AtomicHost-28-20180625.1.x86_64.qcow2 converted.raw (100.00/100%) real 0m11.909s user 0m4.728s sys 0m1.595s So converting on the fly is even little faster then downloading to temporary file and converting. Nir