linuxexpert-practice-labs/labs/lfcs/1-6-virtual-machines/README.md

LFCS 1.6: Virtual machines

Installing libvirt, creating a VM from a cloud image, autostart, more memory and a second disk, snapshots, and deleting a VM.

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 downloads a small cloud image, CirrOS, to /var/lib/le-lab/images/cirros.img; it needs no login for these tasks. libvirt isn't installed: that's part of task 1.

Tasks

1. Install libvirt and create a VM named web1 with 1 GiB of memory from the cloud image. virsh list --all shows web1 running and virsh domifaddr web1 shows an address (give it a minute to boot).
2. Make web1 start whenever the host boots.
3. Give web1 2 GiB of memory and a second 5 GiB disk that stay after it's restarted. After virsh shutdown and virsh start, virsh dominfo shows 2097152 KiB and virsh domblklist web1 shows two disks. CirrOS may ignore virsh shutdown while it's still booting; virsh destroy powers it off.
4. Snapshot web1, create a file inside the guest, and revert. Keep the snapshot. Check the revert yourself: the file is gone (log in on virsh console web1 as user cirros, password gocubsgo).
5. Create a second VM, web2, from the same image, and take a snapshot of it. Write the full paths of web2's disk files to /root/lab-answers/5, one per line. Then delete web2 and its disks: virsh destroy web2, delete its snapshots (virsh snapshot-delete, or add --snapshots-metadata), then virsh undefine web2 --remove-all-storage.

Hints

• qemu-kvm libvirt virt-install on RHEL relatives; qemu-system-x86 libvirt-daemon-system virtinst on Ubuntu. If virsh list can't connect on a RHEL relative, start the virt*d sockets (the chapter has the loop).
• qemu-img create -f qcow2 -F qcow2 -b BACKING NEW.qcow2, virt-install --import, virt-install --osinfo list.
• virsh net-start default, virsh net-autostart default.
• virsh autostart, virsh dominfo.
• virsh setmaxmem and virsh setmem with --config; virsh attach-disk --persistent.
• virsh snapshot-create-as, virsh snapshot-list, virsh snapshot-revert.
• virsh domblklist, virsh undefine --remove-all-storage.