Starting Codeready Container with libvirt cause "format of backing image was not specified in the image metadata" - kubernetes

Question

I'm trying to use CRC for testing Openshift 4 on my laptop (Ubuntu 20). CRC version 1.17 doesn't support Virtualbox virtualizazion so following the setup instructions
https://access.redhat.com/documentation/en-us/red_hat_codeready_containers/1.17/html/getting_started_guide/installation_gsg
i'm using libvirt, but when i start the cluster with crc start it launch following error
INFO Checking if oc binary is cached
INFO Checking if podman remote binary is cached
INFO Checking if goodhosts binary is cached
INFO Checking minimum RAM requirements
INFO Checking if running as non-root
INFO Checking if Virtualization is enabled
INFO Checking if KVM is enabled
INFO Checking if libvirt is installed
INFO Checking if user is part of libvirt group
INFO Checking if libvirt daemon is running
INFO Checking if a supported libvirt version is installed
INFO Checking if crc-driver-libvirt is installed
INFO Checking if libvirt 'crc' network is available
INFO Checking if libvirt 'crc' network is active
INFO Checking if NetworkManager is installed
INFO Checking if NetworkManager service is running
INFO Checking if /etc/NetworkManager/conf.d/crc-nm-dnsmasq.conf exists
INFO Checking if /etc/NetworkManager/dnsmasq.d/crc.conf exists
INFO Starting CodeReady Containers VM for OpenShift 4.5.14...
ERRO Error starting stopped VM: virError(Code=55, Domain=18, Message='Requested operation is not valid: format of backing image '/home/claudiomerli/.crc/cache/crc_libvirt_4.5.14/crc.qcow2' of image '/home/claudiomerli/.crc/machines/crc/crc.qcow2' was not specified in the image metadata (See https://libvirt.org/kbase/backing_chains.html for troubleshooting)')
Error starting stopped VM: virError(Code=55, Domain=18, Message='Requested operation is not valid: format of backing image '/home/claudiomerli/.crc/cache/crc_libvirt_4.5.14/crc.qcow2' of image '/home/claudiomerli/.crc/machines/crc/crc.qcow2' was not specified in the image metadata (See https://libvirt.org/kbase/backing_chains.html for troubleshooting)')
I have not experiences with libvirt so i'm stuck on that and online i'm not finding anything...
Thanks

Answer 1

There is an issue with the crc_libvirt_4.5.14 image. The easiest way to fix it is to do a
qemu-img rebase -f qcow2 -F qcow2 -b /home/${USER}/.crc/cache/crc_libvirt_4.5.14/crc.qcow2 /home/${USER}/.crc/machines/crc/crc.qcow2
Now, if you try to do a crc start, you going to face a "Permission denied" error, which is related to Apparmor, unless you whitelisted your home directory. If you don't want to hack around with Apparmor settings, the /var/lib/libvirt/images supposed to be whitelisted. Move the image to there:
sudo mv /home/${USER}/.crc/machines/crc/crc.qcow2 /var/lib/libvirt/images
then edit the virtual machine settings pointing to the new image location: virsh edit crc , then replace the <source file='/home/yourusername/.crc/machines/crc/crc.qcow2'/> to <source file='/var/lib/libvirt/images/crc.qcow2'/>.
Then do the crc start and... that's it.
The relevant Github issues to follow:
https://github.com/code-ready/crc/issues/1596
https://github.com/code-ready/crc/issues/1578