Earlier we looked at how we could use Ubuntu cloud images with KVM. Now we will use the libvirt cli virsh and virt-install to do the same process. virt-install is a part of the virt-manager supporting tools.
Fetch the Ubuntu Cloud image 🔗
This only need to be done once, or when you want to update the cloud image.
- Download a Ubuntu Focal image from Ubuntu Cloud Images.
wget https://cloud-images.ubuntu.com/focal/current/focal-server-cloudimg-amd64.img - Create an empty image in the default storage pool. This is a storage space where we upload the cloud image. Note that we use the correct postfix on the name here.
virsh vol-create-as default focal-server-cloudimg-amd64.qcow2 20G - Upload the downloaded cloud image to the storage pool in the reserved spaced.
virsh vol-upload focal-server-cloudimg-amd64.qcow2 focal-server-cloudimg-amd64.img --sparse --pool default
Create the VM 🔗
Now we use the cloud image as a template for all our new VMs. Change the size and virt-install parameters to make it your own.
- Clone the cloud image to
my-vm01.qcow2. The clone is our bootable VM.virsh vol-clone focal-server-cloudimg-amd64.qcow2 my-vm01.qcow2 --pool default - Resize the new image to the prefered size, in our example
20GB.virsh vol-resize my-vm01.qcow2 20G --pool default - Create the VM.
virt-install --os-variant short-id=ubuntu20.04 --import --disk vol=default/my-vm01.qcow2,bus=virtio,driver.discard=unmap --cloud-init --network bridge=virbr0,model=virtio --cpu host --vcpus 2 --memory 1024 --name my-vm01
Short explanation of the last command parameters.
--import— import an existing image--disk— usemy-vm01.qcow2indefaultpool with virtio og and hole punching--cloud-init— use cloud init, installation will set a random root password--network— use the default bridgevirbr0with virtio--cpu— copy host cpu information, change if you need better compatibility--vcpus— number of virtual cpus--memory— MB memory--name— VM name