virsh

KVM virtual machine management via libvirt. Lifecycle, autostart, console access, disk/network inspection, snapshots, and bulk operations.

VM Lifecycle

List all VMs — running and stopped

sudo virsh list --all

Start a single VM

sudo virsh start vyos-01

Start VMs in dependency order — with loop and status

for vm in vyos-01 bind-01 vault-01 home-dc01 ipa-01 ipsk-mgr-01 9800-WLC-01 k3s-master-01; do
  sudo virsh start $vm && echo "$vm started" || echo "$vm FAILED"
  sleep 5
done

Graceful shutdown — sends ACPI power button signal

sudo virsh shutdown vyos-02

Hard power off — immediate, no graceful shutdown (like pulling the power cord)

sudo virsh destroy 9800-WLC-02

destroy does NOT delete the VM or its disk. It’s a hard power-off. Use it when shutdown hangs or you need the VM stopped immediately.

Reboot

sudo virsh reboot vyos-01

Autostart

List VMs with autostart status

sudo virsh list --all --autostart

Enable autostart — VM starts automatically on hypervisor boot

sudo virsh autostart vyos-01

Enable autostart for all critical VMs — loop pattern

for vm in vyos-01 bind-01 vault-01 home-dc01 ipa-01 ipsk-mgr-01 9800-WLC-01 k3s-master-01; do
  sudo virsh autostart $vm && echo "$vm autostart enabled"
done

Disable autostart

sudo virsh autostart --disable k3s-master-01

Console Access

Attach to VM serial console — like plugging a monitor into the VM

sudo virsh console vyos-02

Exit console — Ctrl+] (right bracket)

Ctrl + ]

Some VMs (IOS-XE, ISE) don’t have serial console configured. You’ll connect but see no output. Use SSH instead for those.

VM Inspection

List VM disk images — shows where qcow2 files are stored

sudo virsh domblklist 9800-WLC-02
#  Target   Source
#  hda      /mnt/nas/vms/9800-WLC-02.qcow2

List VM network interfaces — shows bridge, MAC, vnet mapping

sudo virsh domiflist ise-02
#  Interface   Type     Source    Model    MAC
#  vnet2       bridge   br-mgmt   virtio   52:54:00:27:3d:70

Dump full VM XML config

sudo virsh dumpxml vyos-02

Extract just the disk section from XML

sudo virsh dumpxml 9800-WLC-02 | awk '/<disk/,/<\/disk/'

VM Modification

Change VM disk path — move image from NAS to local storage

sudo virt-xml 9800-WLC-02 --edit --disk path=/var/lib/libvirt/images/9800-WLC-02.qcow2

Attach a new network interface — add NIC to bridge

sudo virsh attach-interface vyos-02 bridge br-ispb --model virtio --persistent

Detach a network interface by MAC

sudo virsh detach-interface vyos-02 bridge --mac 52:54:00:31:eb:e3 --persistent

--persistent saves the change to the VM definition. Without it, the change is lost on VM restart.

Snapshots

Create a snapshot — safety net before changes

sudo virsh snapshot-create-as vyos-02 pre-migration "Before NIC reorder"

List snapshots

sudo virsh snapshot-list vyos-02

Revert to snapshot — instant rollback

sudo virsh snapshot-revert vyos-02 pre-migration

Delete snapshot — do this within 24-48h, snapshots degrade disk I/O

sudo virsh snapshot-delete vyos-02 pre-migration

Bulk Operations

Shutdown all VMs on a hypervisor

for vm in $(sudo virsh list --name); do
  sudo virsh shutdown $vm
done

Restart all VMs — triggers libvirt hooks on start

for vm in vyos-02 ise-02 bind-02 vault-02 vault-03 9800-WLC-02; do
  sudo virsh shutdown $vm
done
sleep 15
for vm in vyos-02 ise-02 bind-02 vault-02 vault-03 9800-WLC-02; do
  sudo virsh start $vm
done