"guix system vm" to libvirt XML domain

[Giovanni Biscuolo <g@xelera.eu>]

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Hi!

I'm using guix on a foreign distro (Debian 9) and I'm already using
libvirtd to manage some KVM guests; I'd like to also manage "guix
system vm" generated ones using libvirt

it would be great to be able to automatically manage the (re)definition
of VMs (and containers?) on - possibly remote - libvirtd servers using a
distributedVM.scm config :-): WDYT?

anyway... as for now it must be "manually" managed and this is
what I'm doing: it fails at the end, what am I doing wrong?

is there a better way to do it?

1. I save the "command line" from the script generated by "guix system
vm" (except the last "@") calling this "container.minimal.args.orig

--8<---------------cut here---------------start------------->8---
/gnu/store/4pnx934k40wni57r5swj2kr29l1j549f-qemu-3.1.0/bin/qemu-system-x86_64 -kernel /gnu/store/y5aiijqiqna1y8ypn6c0jp367813xxnc-linux-libre-4.20.3/bzImage -initrd /gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/initrd -append "--root=/dev/vda1 --system=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system --load=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/boot" -enable-kvm -no-reboot -net nic,model=virtio -object rng-random,filename=/dev/urandom,id=guixsd-vm-rng -device virtio-rng-pci,rng=guixsd-vm-rng -virtfs local,path="/gnu/store",security_model=none,mount_tag="TAGjoptajej2oynju6yvboauz7pl6uj" -vga std -drive file=/gnu/store/4mz1qqv7h5g5885q1aq0izlmy01knf1g-qemu-image,if=virtio,cache=writeback,werror=report,readonly -m  256
--8<---------------cut here---------------end--------------->8---

2. try to convert it to libvirt XML domain definition

--8<---------------cut here---------------start------------->8---
$ virsh --connect qemu:///system domxml-from-native qemu-argv container-minimal.args.orig 
error: internal error: malformed keyword arguments in 'file=/gnu/store/4mz1qqv7h5g5885q1aq0izlmy01knf1g-qemu-image,if=virtio,cache=writeback,werror=report,readonly'
--8<---------------cut here---------------end--------------->8---

3. remove the "readonly" keyword from the last "-drive" arg, calling this
"container.minimal.args" (that *must* be then manually added to the XML
definition)

--8<---------------cut here---------------start------------->8---
/gnu/store/4pnx934k40wni57r5swj2kr29l1j549f-qemu-3.1.0/bin/qemu-system-x86_64 -kernel /gnu/store/y5aiijqiqna1y8ypn6c0jp367813xxnc-linux-libre-4.20.3/bzImage -initrd /gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/initrd -append "--root=/dev/vda1 --system=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system --load=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/boot" -enable-kvm -no-reboot -net nic,model=virtio -object rng-random,filename=/dev/urandom,id=guixsd-vm-rng -device virtio-rng-pci,rng=guixsd-vm-rng -virtfs local,path="/gnu/store",security_model=none,mount_tag="TAGjoptajej2oynju6yvboauz7pl6uj" -vga std -drive file=/gnu/store/4mz1qqv7h5g5885q1aq0izlmy01knf1g-qemu-image,if=virtio,cache=writeback,werror=report -m  256
--8<---------------cut here---------------end--------------->8---

4. converting the file above

--8<---------------cut here---------------start------------->8---
$ virsh --connect qemu:///system domxml-from-native qemu-argv container-minimal.args
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>unnamed</name>
  <uuid>894f668e-32a5-4331-9d30-8604b89ae359</uuid>
  <memory unit='KiB'>262144</memory>
  <currentMemory unit='KiB'>262144</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-2.8'>hvm</type>
    <kernel>/gnu/store/y5aiijqiqna1y8ypn6c0jp367813xxnc-linux-libre-4.20.3/bzImage</kernel>
    <initrd>/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/initrd</initrd>
    <cmdline>--root=/dev/vda1 --system=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system --load=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/boot</cmdline>
  </os>
  <features>
    <acpi/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>destroy</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/gnu/store/4pnx934k40wni57r5swj2kr29l1j549f-qemu-3.1.0/bin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='writeback' error_policy='report'/>
      <source file='/gnu/store/4mz1qqv7h5g5885q1aq0izlmy01knf1g-qemu-image'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </disk>
    <controller type='usb' index='0' model='piix3-uhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='sdl'/>
    <video>
      <model type='vga' vram='16384' heads='1' primary='yes'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='none'/>
  </devices>
  <qemu:commandline>
    <qemu:arg value='-object'/>
    <qemu:arg value='rng-random,filename=/dev/urandom,id=guixsd-vm-rng'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='virtio-rng-pci,rng=guixsd-vm-rng'/>
    <qemu:arg value='-virtfs'/>
    <qemu:arg value='local,path=&quot;/gnu/store&quot;,security_model=none,mount_tag=&quot;TAGjoptajej2oynju6yvboauz7pl6uj&quot;'/>
  </qemu:commandline>
</domain>
--8<---------------cut here---------------end--------------->8---

5. unfortunately some command line args are not automatically converted,
so I have to "manually" convert it [1]... also adapting some parametrs
to my needs (e.g. name, memory, network, graphics); saving as
container-minimal-fixed.xml


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<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>container-minimal</name>
  <uuid>ecfe2538-5315-44aa-bba5-8fe4d86d5397</uuid>
  <memory unit='GB'>2</memory>
  <currentMemory unit='GB'>2</currentMemory>
  <vcpu placement='static'>2</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-2.8'>hvm</type>
    <kernel>/gnu/store/y5aiijqiqna1y8ypn6c0jp367813xxnc-linux-libre-4.20.3/bzImage</kernel>
    <initrd>/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/initrd</initrd>
    <cmdline>--root=/dev/vda1 --system=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system --load=/gnu/store/9xgqs9zf51i9binqjl5hgl8gl7ql40hc-system/boot</cmdline>
  </os>
  <features>
    <acpi/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>destroy</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/gnu/store/4pnx934k40wni57r5swj2kr29l1j549f-qemu-3.1.0/bin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='writeback' error_policy='report'/>
      <source file='/gnu/store/4mz1qqv7h5g5885q1aq0izlmy01knf1g-qemu-image'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
      <readonly/>
    </disk>
    <controller type='usb' index='0' model='piix3-uhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' port='3003' autoport='no' listen='127.0.0.1'>
      <listen type='address' address='127.0.0.1'/>
    </graphics>
    <video>
      <model type='qxl' ram='65536' vram='16384' vgamem='16384' heads='1' primary='yes'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='none'/>
    <rng model='virtio'>
     <backend model='random'>/dev/urandom</backend>
    </rng>
    <interface type='network'>
     <mac address='52:54:00:ae:72:b9'/>
     <source network='gblabs'/>
     <model type='rtl8139'/>
   </interface>
  </devices>
  <filesystem type='mount' accessmode='none'>
   <source dir='/gnu/store'/>
   <target dir='TAGjoptajej2oynju6yvboauz7pl6uj'/>
  </filesystem>
</domain>

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6. register the domain definition in libvirtd

--8<---------------cut here---------------start------------->8---
$ virsh --connect qemu:///system define container-minimal-fixed.xml
Domain container-minimal defined from container-minimal-fixed.xml
--8<---------------cut here---------------end--------------->8---

7. start the VM, connect via SPICE and see the VM does not boot due to
an error in procedure mount, falling back to the guile REPL; the backtrace
is:

--8<---------------cut here---------------start------------->8---
In gnu/build/linux-boot.scm:
   516:13  2 (_)
    367:8  1 (mount-root-file-system "/dev/vda1" "ext4" # _)
In unknown file:
           0 (mount "/dev/vda1" "/real-root" "ext4" 1 #<undefined>)
--8<---------------cut here---------------end--------------->8---

any hint please?

Thanks!
Giovanni

[1] using this docs as ref:
https://wiki.qemu.org/Documentation/9psetup#Starting_the_Guest_using_libvirt
https://libvirt.org/formatdomain.html#elementsRng

-- 
Giovanni Biscuolo

Xelera IT Infrastructures