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Creating a compressed and minimal KVM template
Note❗: This is purely for self-learning, so that I can learn how to automate my Virtual Machines using Libvirt
virt-sysprep virt-sysprep
(reset) (add user, keys, logos)
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dd v dd v
original guest ----> template ---------> copied ------> custom
template guestTo start this you first need to install a virtual machine in KVM, either by using virt-install or virt-manager. Automating this is possible via kickstart or by downloading a cloud image, I did it manually.
This was the base image after installation and it was around 2.1 GB on disk and 10GB virtually.
qemu-img info "rocky-linux.qcow2"
file format: qcow2
virtual size: 10 GiB (10737418240 bytes)
disk size: 2.25 GiBI've used virt-sparsify instead of dd with compress which made the image size 1GB on disk and took around 5 minutes for it to complete
sudo virt-sparsify --tmp=./ --compress rocky-linux.qcow2 rocky-linux-template.qcow2Final file “rocky-linux-template.qcow2” which is 1GB 🔥.
sudo qemu-img info rocky-linux-template.qcow2
virtual size: 10 GiB (10737418240 bytes)
disk size: 0.993 GiBNow let’s virt-sysprep it
sudo virt-sysprep -a rocky-linux-template.qcow2Time to virt-sparsify it again
sudo virt-sparsify --tmp=./ --compress rocky-linux-template.qcow2 rocky-linux-g1.qcow2Time to add the ssh keys and relabel the system
sudo virt-sysprep --format=qcow2 -a rocky-linux-g1.qcow2 \
--ssh-inject root:file:.ssh/id_rsa.pub \
--selinux-relabel --hostname rk-g1-minimalCreating a guest out of this
virt-install --connect qemu:///system \
--name "${VM_NAME}" \
--disk "${VM_DISK_PATH}",target.bus=virtio \
--boot hd \
--memory=1048 \
--noautoconsole \
--graphics none \
--os-variant "${VM_OS_VARIANT}" \
--vcpus 2 \
--cpu host \
--os-type linux \
--network network=br0,model=virtio \
--console pty,target_type=serialAnd it’s done ✌️
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