Ownership of qcow2 images created by virt-clone is root

16 Mar 2022

What happen and what’s wrong

I created a new KVM Guest by using virt-clone as a non-root user, and got permission issue when I tried to use virt-sysprep for changing the hostname:

~]$ virt-clone -o jiyin-freebsd-130 --name clone-freebsd13 --file ~/VMs/FreeBSD-13.0/clone-freebsd13/freebsd13.qcow2
Allocating 'freebsd13.qcow2'                                                                        |  27 GB  00:00:02 
~]$ ls -l ~/VMs/FreeBSD-13.0/clone-freebsd13
total 3393220
-rw-------. 1 root root 3474718720 Mar 18 15:42 freebsd13.qcow2

Cause and Workaround

By googling, found that the root cause is I use the qemu:///system as the default hypervisor. that’s because I’d like to use the default network.

~]$ cat ~/.config/libvirt/libvirt.conf
uri_default = "qemu:///system"

But now if I create a new Guest with virt-clone I will face the problem of not being able to customize the new VM. what should I do? luckily after exploring I found virt-clone has a –print-xml option, so I can manually copy the image file and then use virsh define command to create the new VM ^v^. share the code segment here:

	rm -f $dstpath/${dstname}.qcow2
	virt-clone -o ${srcname} --name ${dstname} --file $dstpath/${dstname}.qcow2 \
		--print-xml >$dstpath/${dstname}.xml
	[[ -s $dstpath/${dstname}.xml ]] || return 1
	#Note: https://www.reddit.com/r/archlinux/comments/obn999/ownership_of_qcow2_images_created_by_virtmanager/
	#^^^^ why don't use virt-clone directly

	read srcimage < <(_vmblklist "$srcname")
	cp -v --sparse=always $srcimage $dstpath/${dstname}.qcow2
	chcon --reference=${srcpath%/*} -R $dstpath
	virsh define $dstpath/${dstname}.xml
	vmhomedir ${dstname}

	LIBGUESTFS_BACKEND=direct virt-sysprep -d ${dstname} \
		--enable customize,user-account,net-hostname,net-hwaddr,machine-id \
		--hostname $dstname \
		--remove-user-accounts bar \
		--run-command "ls -l"
	virsh start $dstname

Additional: if use RHEL-7 as the VM host OS

seems we will always get VM image with Owner root:root, on RHEL-7 VM host.
I think it might be a bug of libvirtd, I’m not sure,,

when we start VM, libvirtd will change the image owner to qemu:qemu, and after stop(poweroff or virsh destroy)
the image owner will be changed back to root:root on RHEL-7 and previous value on Fedora-3x
need more investigating

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