[libvirt-users] Mount URL as cdrom/iso KVM/QEMU

[Inception Hosting]

Hi Folks,


According to the examples in http://libvirt.org/formatdomain.html#elementsDisks it should be possible to mount an iso /url as a cdrom, the example given is:


</disk>
<disk type='network' device='cdrom'>
<driver name='qemu' type='raw'/>
<source protocol="http" name="url_path">
<host name="hostname" port="80"/>
</source>
<target dev='hde' bus='ide' tray='open'/>
<readonly/>
</disk>


I am unable to get this to work at all and wondered if I am just missing something obvious:

Boot failed: Could not read from CDROM (code 0003)

Actual XML in use snippet:

<disk type='network' device='cdrom'>
<driver name='qemu' type='raw'/>
<source protocol="http" name="/debian-cd/current/amd64/iso-cd/debian-9.5.0-amd64-netinst.iso">
<host name="mirror.bytemark.co.uk" port="80"/>
</source>
<target dev='hdb' bus='ide' tray='open'/>
<readonly/>
</disk>
libvirtd (libvirt) 3.9.0 QEMU emulator version 2.10.0

Is anyone able to offer any assistance or tips?

I have tried putting the complete path including fqdn in the url_path as well, with and without http://

Many Thanks.

Anthony.

[Daniel P. Berrangé]

On Wed, Aug 08, 2018 at 12:11:22PM +0000, Inception Hosting wrote:
> Hi Folks,
>
>
> According to the examples in http://libvirt.org/formatdomain.html#elementsDisks it should be possible to mount an iso /url as a cdrom, the example given is:
>
>
> </disk>
> <disk type='network' device='cdrom'>
> <driver name='qemu' type='raw'/>
> <source protocol="http" name="url_path">
> <host name="hostname" port="80"/>
> </source>
> <target dev='hde' bus='ide' tray='open'/>
> <readonly/>
> </disk>
>
>
> I am unable to get this to work at all and wondered if I am just missing something obvious:
>
> Boot failed: Could not read from CDROM (code 0003)
>
> Actual XML in use snippet:
>
> <disk type='network' device='cdrom'>
> <driver name='qemu' type='raw'/>
> <source protocol="http" name="/debian-cd/current/amd64/iso-cd/debian-9.5.0-amd64-netinst.iso">
> <host name="mirror.bytemark.co.uk" port="80"/>
> </source>
> <target dev='hdb' bus='ide' tray='open'/>
> <readonly/>
> </disk>
> libvirtd (libvirt) 3.9.0 QEMU emulator version 2.10.0
>
> Is anyone able to offer any assistance or tips?

This XML looks reasonable to me. There have been bugs in QEMU's curl driver
though, so it might be worth retesting with latest QEMU 2.12.0, or even the
3.0.0-rc4 release from yesterday, to check if its a bug in that version of
QEMU


Regards,
Daniel
--
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[Vasiliy Tolstov]

ср, 8 авг. 2018 г. в 15:11, Inception Hosting <***@inceptionhosting.com>:
>
> Hi Folks,
>
>
> According to the examples in http://libvirt.org/formatdomain.html#elementsDisks it should be possible to mount an iso /url as a cdrom, the example given is:
>

Usually such errors because url not available from host system. Can
you try curl this host and address from node?


--
Vasiliy Tolstov,
e-mail: ***@selfip.ru

[Inception Hosting]

Resolved this morning,


the issue is that the qemu-kvm-ev rpm's released by centos have not been compiled with curl support, I rebuild it myself from source with curl support and it works fine now.


Thanks you for your input everyone.

________________________________
From: Vasiliy Tolstov <***@selfip.ru>
Sent: 09 August 2018 10:32:07
To: Inception Hosting
Cc: libvirt-***@redhat.com
Subject: Re: [libvirt-users] Mount URL as cdrom/iso KVM/QEMU

ÓÒ, 8 Á×Ç. 2018 Ç. × 15:11, Inception Hosting <***@inceptionhosting.com>:
>
> Hi Folks,
>
>
> According to the examples in http://libvirt.org/formatdomain.html#elementsDisks it should be possible to mount an iso /url as a cdrom, the example given is:
>

Usually such errors because url not available from host system. Can
you try curl this host and address from node?


--
Vasiliy Tolstov,
e-mail: ***@selfip.ru

[Daniel P. Berrangé]

On Thu, Aug 09, 2018 at 10:20:54AM +0000, Inception Hosting wrote:
> Resolved this morning,
>
>
> the issue is that the qemu-kvm-ev rpm's released by centos have not
> been compiled with curl support, I rebuild it myself from source with
> curl support and it works fine now.

Hmm that's bad, because if curl was disabled, we really want to have
QEMU refuse to startup, rather than start & give you an inaccessible
file. So this feels like a QEMU bug to me that ought to be reported.


Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
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[Inception Hosting]

Just a quick correction and apologies, the actual issue is that http will not work, https will so I dont think this is a bug as such I think this is by design likely for security.


Looking at the man page for qemu-kvm it states http will work with examples given however only https works, my best guess from looking at the spec file from the srpm is that it has only been enabled in the centos qemu-kvm-ev with https:


except from spec file:

- Resolves: bz#1132569
(RFE: Enable curl driver in qemu-kvm-rhev: https only)


example working XML except:


<disk type='network' device='cdrom'>
<driver name='qemu' type='raw'/>
<source protocol="https" name="/debian-cd/current/amd64/iso-cd/debian-9.5.0-amd64-netinst.iso">
<host name="mirror.bytemark.co.uk" port="443"/>
</source>
<target dev='hdb' bus='ide' tray='closed'/>
<readonly/>


I have tested this on a base install with the regular packages and can confirm that it works fine over https.


Thanks again and sorry for any confusion caused.

________________________________
From: Daniel P. Berrangé <***@redhat.com>
Sent: 09 August 2018 11:29:25
To: Inception Hosting
Cc: Vasiliy Tolstov; libvirt-***@redhat.com
Subject: Re: [libvirt-users] Mount URL as cdrom/iso KVM/QEMU

On Thu, Aug 09, 2018 at 10:20:54AM +0000, Inception Hosting wrote:
> Resolved this morning,
>
>
> the issue is that the qemu-kvm-ev rpm's released by centos have not
> been compiled with curl support, I rebuild it myself from source with
> curl support and it works fine now.

Hmm that's bad, because if curl was disabled, we really want to have
QEMU refuse to startup, rather than start & give you an inaccessible
file. So this feels like a QEMU bug to me that ought to be reported.


Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|

[Daniel P. Berrangé]

On Thu, Aug 09, 2018 at 10:50:46AM +0000, Inception Hosting wrote:
> Just a quick correction and apologies, the actual issue is that http
> will not work, https will so I dont think this is a bug as such I
> think this is by design likely for security.
>
>
> Looking at the man page for qemu-kvm it states http will work with
> examples given however only https works, my best guess from looking
> at the spec file from the srpm is that it has only been enabled in
> the centos qemu-kvm-ev with https:

Yes, the qemu RPMs in centos & RHEL have disabled support for http://
protocol, however, I expect that to immediately fail when trying to
start the guest. eg

# /usr/libexec/qemu-kvm -drive file=http://example.com/foo/bar -accel tcg
qemu-kvm: -drive file=http://example.com/foo/bar: Driver 'http' is not whitelisted

so I'm puzzelled why your guest successfully started at all with a
http protocol in use.

Are you able to share your QEMU log from /var/log/libvirt/qemu/$GUESTNAME.log
from a VM that fails to launch with http ?

Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|

[Inception Hosting]

Hi Daniel,


I have noticed that it will fail exactly as you said if <cdrom> is first in the boot order, if <hd> is first in the boot order the XML validates and it starts as usual.

first in log except below is with cdrom set to first in boot order, second is with hd set first.

2018-08-09 11:39:28.625+0000: starting up libvirt version: 3.9.0, package: 14.el7_5.6 (CentOS BuildSystem <http://bugs.centos.org>, 2018-06-27-14:13:57, x86-01.bsys.centos.org), qemu version: 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1), hostname: devnode9.com
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm -name guest=kvm104,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-82-kvm104/master-key.aes -machine pc-i440fx-rhel7.5.0,accel=kvm,usb=off,dump-guest-core=off -m 1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 5827d6a9-ef0e-4331-9d0e-fa742c70d596 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-82-kvm104/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=http://distro.ibiblio.org:80/puppylinux/puppy-xenial/32/xenialpup-7.5-uefi.iso,format=raw,if=none,id=drive-ide0-0-1,readonly=on -device ide-cd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1,bootindex=2 -drive file=/dev/Kvmvol/kvm104_img,format=raw,if=none,id=drive-virtio-disk0,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=30,id=hostnet0,vhost=on,vhostfd=32 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:16:3c:07:e0:c9,bus=pci.0,addr=0x3 -device usb-tablet,id=input0,bus=usb.0,port=1 -vnc 0.0.0.0:4,password -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -msg timestamp=on
2018-08-09T11:39:28.690350Z qemu-kvm: -drive file=http://distro.ibiblio.org:80/puppylinux/puppy-xenial/32/xenialpup-7.5-uefi.iso,format=raw,if=none,id=drive-ide0-0-1,readonly=on: Driver 'http' is not whitelisted
2018-08-09 11:39:28.699+0000: shutting down, reason=failed


2018-08-09 11:40:04.963+0000: starting up libvirt version: 3.9.0, package: 14.el7_5.6 (CentOS BuildSystem <http://bugs.centos.org>, 2018-06-27-14:13:57, x86-01.bsys.centos.org), qemu version: 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1), hostname: devnode9.com
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm -name guest=kvm104,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-83-kvm104/master-key.aes -machine pc-i440fx-rhel7.5.0,accel=kvm,usb=off,dump-guest-core=off -m 1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 5827d6a9-ef0e-4331-9d0e-fa742c70d596 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-83-kvm104/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive if=none,id=drive-ide0-0-1,readonly=on -device ide-cd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1,bootindex=2 -drive file=/dev/Kvmvol/kvm104_img,format=raw,if=none,id=drive-virtio-disk0,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=30,id=hostnet0,vhost=on,vhostfd=32 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:16:3c:07:e0:c9,bus=pci.0,addr=0x3 -device usb-tablet,id=input0,bus=usb.0,port=1 -vnc 0.0.0.0:4,password -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -msg timestamp=on

So my best guess based on the logs is that http is simply being ignored when it is not set to primary, not sure if that is the desired behavior.

Cheers.

________________________________
From: Daniel P. Berrangé <***@redhat.com>
Sent: 09 August 2018 12:27
To: Inception Hosting
Cc: Vasiliy Tolstov; libvirt-***@redhat.com
Subject: Re: [libvirt-users] Mount URL as cdrom/iso KVM/QEMU

On Thu, Aug 09, 2018 at 10:50:46AM +0000, Inception Hosting wrote:
> Just a quick correction and apologies, the actual issue is that http
> will not work, https will so I dont think this is a bug as such I
> think this is by design likely for security.
>
>
> Looking at the man page for qemu-kvm it states http will work with
> examples given however only https works, my best guess from looking
> at the spec file from the srpm is that it has only been enabled in
> the centos qemu-kvm-ev with https:

Yes, the qemu RPMs in centos & RHEL have disabled support for http://
protocol, however, I expect that to immediately fail when trying to
start the guest. eg

# /usr/libexec/qemu-kvm -drive file=http://example.com/foo/bar -accel tcg
qemu-kvm: -drive file=http://example.com/foo/bar: Driver 'http' is not whitelisted

so I'm puzzelled why your guest successfully started at all with a
http protocol in use.

Are you able to share your QEMU log from /var/log/libvirt/qemu/$GUESTNAME.log
from a VM that fails to launch with http ?

Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
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Daniel | Flickr<https://www.flickr.com/photos/dberrange>
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Explore Daniel's 1,578 photos on Flickr!



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178 Followers, 60 Following, 136 Posts - See Instagram photos and videos from Daniel Berrangé (@dberrange)

[Daniel P. Berrangé]

On Thu, Aug 09, 2018 at 11:46:24AM +0000, Inception Hosting wrote:
> Hi Daniel,
>
>
> I have noticed that it will fail exactly as you said if <cdrom> is first in
> the boot order, if <hd> is first in the boot order the XML validates and it starts as usual.

That is interesting....

>
> first in log except below is with cdrom set to first in boot order, second is with hd set first.
>
> 2018-08-09 11:39:28.625+0000: starting up libvirt version: 3.9.0, package: 14.el7_5.6 (CentOS BuildSystem <http://bugs.centos.org>, 2018-06-27-14:13:57, x86-01.bsys.centos.org), qemu version: 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1), hostname: devnode9.com

> -drive file=http://distro.ibiblio.org:80/puppylinux/puppy-xenial/32/xenialpup-7.5-uefi.iso,format=raw,if=none,id=drive-ide0-0-1,readonly=on
> -device ide-cd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1,bootindex=2
> -drive file=/dev/Kvmvol/kvm104_img,format=raw,if=none,id=drive-virtio-disk0,cache=none
>< -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1

Here we actually see the HD set first (bootindex=1) and CDROM set secound (bootindex=2)

> 2018-08-09 11:40:04.963+0000: starting up libvirt version: 3.9.0, package: 14.el7_5.6 (CentOS BuildSystem <http://bugs.centos.org>, 2018-06-27-14:13:57, x86-01.bsys.centos.org), qemu version: 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1), hostname: devnode9.com

> -drive if=none,id=drive-ide0-0-1,readonly=on
> -device ide-cd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1,bootindex=2
> -drive file=/dev/Kvmvol/kvm104_img,format=raw,if=none,id=drive-virtio-disk0,cache=none
> -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1

And this is the same boot order. What's different, however ,is that libvirt has launched
the QEMU with no media present in the CDROM tray, so there's no URL for QEMU to complain
about.

I dont know what would have caused libvirt to drop the URL for this CDROM...


>
> Cheers.
>
> ________________________________
> From: Daniel P. Berrangé <***@redhat.com>
> Sent: 09 August 2018 12:27
> To: Inception Hosting
> Cc: Vasiliy Tolstov; libvirt-***@redhat.com
> Subject: Re: [libvirt-users] Mount URL as cdrom/iso KVM/QEMU
>
> On Thu, Aug 09, 2018 at 10:50:46AM +0000, Inception Hosting wrote:
> > Just a quick correction and apologies, the actual issue is that http
> > will not work, https will so I dont think this is a bug as such I
> > think this is by design likely for security.
> >
> >
> > Looking at the man page for qemu-kvm it states http will work with
> > examples given however only https works, my best guess from looking
> > at the spec file from the srpm is that it has only been enabled in
> > the centos qemu-kvm-ev with https:
>
> Yes, the qemu RPMs in centos & RHEL have disabled support for http://
> protocol, however, I expect that to immediately fail when trying to
> start the guest. eg
>
> # /usr/libexec/qemu-kvm -drive file=http://example.com/foo/bar -accel tcg
> qemu-kvm: -drive file=http://example.com/foo/bar: Driver 'http' is not whitelisted
>
> so I'm puzzelled why your guest successfully started at all with a
> http protocol in use.
>
> Are you able to share your QEMU log from /var/log/libvirt/qemu/$GUESTNAME.log
> from a VM that fails to launch with http ?
>
> Regards,
> Daniel
> --
> |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
> [https://c1.staticflickr.com/1/873/40602347890_5a83293856_b.jpg]<https://www.flickr.com/photos/dberrange>
>
> Daniel | Flickr<https://www.flickr.com/photos/dberrange>
> www.flickr.com
> Explore Daniel's 1,578 photos on Flickr!
>
>
>
> |: https://libvirt.org -o- https://fstop138.berrange.com :|
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> libvirt.org
> libvirt, virtualization, virtualization API
>
>
>
> |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
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>
> Daniel Berrangé (@dberrange) • Instagram photos and videos<https://www.instagram.com/dberrange>
> www.instagram.com
> 178 Followers, 60 Following, 136 Posts - See Instagram photos and videos from Daniel Berrangé (@dberrange)
>
>
>

Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
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