linuxexpert-practice-labs/labs/linux-plus/1-7-2-managing-vms/README.md

Linux+ 1.7.2: Managing virtual machines

Creating a VM from a cloud image with virt-install, suspending, resizing and shutting it down, and a snapshot to undo a mistake.

Before you start

The VM you run this lab on needs nested virtualization (the CPU flag vmx or svm inside it) and about 6 GiB of memory, plus internet access. The lab installs QEMU, libvirt and virt-install (the KVM host from chapter 1.7.1) and downloads a small cloud image, CirrOS, to /var/lib/le-lab/images/cirros.img. Use it where the chapter downloads a Rocky Linux or Ubuntu image (or download one of those yourself). Its user is cirros, password gocubsgo.

Tasks

1. Create a VM named lab1 from the cloud image: copy it to /var/lib/libvirt/images/lab1.qcow2, grow that to 10 GiB, and import it with virt-install, with 1 GiB of memory, one vCPU, a VirtIO disk, a VirtIO network card on the default network, and a generated root password from cloud-init. virsh list --all shows it, and virsh domifaddr lab1 shows its address once it has booted.
2. Suspend and resume lab1, give it 768 MiB of memory while it runs, then shut it down. Not graded.
3. Start lab1 again, snapshot it as clean, break something inside it (log in on virsh console lab1 and run rm -rf /etc/ssh; Ctrl+] leaves the console), and revert to the snapshot.

When le-lab check passes, clean up as the chapter shows (task 4: delete the snapshot, then destroy and undefine lab1 with its storage), or leave it to le-lab reset.

Hints

• On the RHEL family, start the libvirt sockets first: systemctl enable --now virtqemud.socket virtnetworkd.socket virtstoraged.socket.
• qemu-img resize; virt-install --import --disk PATH,bus=virtio --network network=default,model=virtio --os-variant detect=on,require=off --cloud-init root-password-generate=on --noautoconsole.
• virsh suspend, virsh resume, virsh setmem lab1 768M --live, virsh shutdown, virsh domstate; CirrOS may ignore virsh shutdown while it's still booting, and virsh destroy powers it off.
• virsh snapshot-create-as lab1 clean, virsh snapshot-list lab1, virsh snapshot-revert lab1 clean.