Virtualization and Provisioning¶

Running virtual machines with KVM and libvirt, and provisioning them at scale with images, cloud-init and Kickstart. Low interview weight, but core to LFCS and to how hosts are actually built in a cloud.

Revision Card¶

Fact	Value
Stack	KVM (kernel) + QEMU (hardware) + libvirt (management)
KVM needs	`vmx`/`svm` CPU flag and `/dev/kvm`
Host check	`virt-host-validate qemu`
Disk formats	qcow2 (thin, snapshots) vs raw (flat, fast)
Clone must reset	machine-id and SSH host keys
Template cleanup	`virt-sysprep`
cloud-init	Configures a cloud image on first boot, once per instance
Kickstart	Automates a full RHEL install (Anaconda)
Image mode	`bootc`: boot from an OCI image, transactional updates

Task	Command
Validate KVM support	`virt-host-validate qemu`
List VMs	`virsh list --all`
Create a VM	`virt-install --name x --memory 2048 --disk size=20 ...`
Create a disk	`qemu-img create -f qcow2 vm.qcow2 20G`
Inspect a disk	`qemu-img info vm.qcow2`
Clean a template	`virt-sysprep -a template.qcow2`
Reset machine-id	`truncate -s 0 /etc/machine-id`
Regenerate host keys	`rm /etc/ssh/ssh_host_*; ssh-keygen -A`
Validate cloud-config	`cloud-init schema --config-file user-data`
Re-run cloud-init	`cloud-init clean; reboot`

Topic Map¶

File	Covers	Track	Weight
KVM and libvirt	The KVM/QEMU/libvirt stack, `virsh`, `virt-install`, networking	Advanced	Low
VM Images and Cloning	qcow2 vs raw, `qemu-img`, resetting identifiers, `virt-sysprep`	Advanced	Low
Cloud-init and Kickstart	First-boot config, user-data, Kickstart, image mode	Core	Low

Scenarios and Labs¶

This module feeds the provisioning side of the practice labs, built in a later phase.