Virtualization and Containers

# Check CPU virtualization support
grep -Ec '(vmx|svm)' /proc/cpuinfo
# Output greater than 0 means supported
 
# Or use the kvm-ok tool
sudo apt install cpu-checker -y
kvm-ok

sudo apt update
sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virtinst virt-manager -y
 
# Add current user to the libvirt group
sudo usermod -aG libvirt $USER
sudo usermod -aG kvm $USER
newgrp libvirt
 
# Verify service is running
sudo systemctl status libvirtd
 
# Verify installation
virsh list --all

# Download ISO
wget https://releases.ubuntu.com/26.04/ubuntu-26.04-live-server-amd64.iso -O /var/lib/libvirt/images/ubuntu-26.04.iso
 
# Create a virtual machine
# Note: --os-variant should match the ISO. If your local osinfo-db does not
# list it yet, confirm with osinfo-query os | grep ubuntu. If it is not listed,
# you can temporarily fall back to ubuntu24.04, or use
# --os-variant detect=on,name=ubuntu26.04
virt-install \
  --name ubuntu-vm \
  --ram 2048 \
  --vcpus 2 \
  --disk path=/var/lib/libvirt/images/ubuntu-vm.qcow2,size=20,format=qcow2 \
  --cdrom /var/lib/libvirt/images/ubuntu-26.04.iso \
  --os-variant ubuntu26.04 \
  --network bridge=virbr0 \
  --graphics vnc,listen=0.0.0.0,port=5901 \
  --console pty,target_type=serial \
  --noautoconsole
 
# Use a cloud image for quick creation (no installation process needed)
wget https://cloud-images.ubuntu.com/releases/26.04/release/ubuntu-26.04-server-cloudimg-amd64.img
 
# Create a disk copy and resize
cp ubuntu-26.04-server-cloudimg-amd64.img /var/lib/libvirt/images/vm-disk.qcow2
qemu-img resize /var/lib/libvirt/images/vm-disk.qcow2 20G
 
# Use with cloud-init
# If osinfo-db does not list ubuntu26.04, you can temporarily fall back to ubuntu24.04
virt-install \
  --name cloud-vm \
  --ram 2048 \
  --vcpus 2 \
  --disk /var/lib/libvirt/images/vm-disk.qcow2 \
  --import \
  --os-variant ubuntu26.04 \
  --network bridge=virbr0 \
  --cloud-init user-data=cloud-config.yaml \
  --noautoconsole

# VM management
virsh list --all                # List all VMs
virsh start ubuntu-vm           # Start
virsh shutdown ubuntu-vm        # Graceful shutdown
virsh destroy ubuntu-vm         # Force shutdown
virsh reboot ubuntu-vm          # Reboot
virsh suspend ubuntu-vm         # Suspend
virsh resume ubuntu-vm          # Resume
virsh undefine ubuntu-vm --remove-all-storage  # Delete VM and its disks
virsh autostart ubuntu-vm       # Enable autostart at boot
 
# Resource adjustment
virsh setvcpus ubuntu-vm 4 --config   # Change CPU count (requires shutdown)
virsh setmaxmem ubuntu-vm 4G --config # Change max memory
virsh setmem ubuntu-vm 4G --config    # Change current memory
 
# Snapshot management
virsh snapshot-create-as ubuntu-vm snap1 "Post-install snapshot"
virsh snapshot-list ubuntu-vm
virsh snapshot-revert ubuntu-vm snap1
virsh snapshot-delete ubuntu-vm snap1
 
# Console access
virsh console ubuntu-vm         # Serial console
virsh vncdisplay ubuntu-vm      # Show VNC port
 
# Disk management
qemu-img info /var/lib/libvirt/images/ubuntu-vm.qcow2
qemu-img resize /var/lib/libvirt/images/ubuntu-vm.qcow2 +10G

# Create a bridge (Netplan configuration)
sudo tee /etc/netplan/01-bridge.yaml << 'EOF'
network:
  version: 2
  renderer: networkd
  ethernets:
    ens33:
      dhcp4: false
  bridges:
    br0:
      interfaces:
        - ens33
      dhcp4: true
      parameters:
        stp: false
        forward-delay: 0
EOF
 
sudo netplan apply
 
# Use the bridge network in libvirt
virsh net-define bridge-net.xml
virsh net-start bridge-net
virsh net-autostart bridge-net

<!-- /etc/libvirt/qemu/example-vm.xml -->
<domain type='kvm'>
  <name>example-vm</name>
  <memory unit='GiB'>4</memory>
  <vcpu placement='static'>2</vcpu>
  <os>
    <type arch='x86_64' machine='q35'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
  </features>
  <cpu mode='host-passthrough'/>
  <devices>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/example-vm.qcow2'/>
      <target dev='vda' bus='virtio'/>
    </disk>
    <interface type='bridge'>
      <source bridge='br0'/>
      <model type='virtio'/>
    </interface>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <graphics type='vnc' port='-1' autoport='yes'/>
  </devices>
</domain>

# Create a VM from XML
virsh define example-vm.xml
virsh start example-vm

# List storage pools
virsh pool-list --all
 
# Create a directory storage pool
virsh pool-define-as mypool dir --target /data/libvirt/images
virsh pool-build mypool
virsh pool-start mypool
virsh pool-autostart mypool
 
# Create a volume
virsh vol-create-as mypool vm-disk.qcow2 20G --format qcow2
 
# List volumes
virsh vol-list mypool

# Install via Snap
sudo snap install lxd
 
# Initialize LXD
sudo lxd init
# Interactive configuration:
# - Clustering: no (standalone)
# - Storage pool: dir or zfs
# - Network: create a new bridge network
# - Auto-update images: yes
 
# Minimal initialization
sudo lxd init --minimal
 
# Add user to the lxd group
sudo usermod -aG lxd $USER
newgrp lxd

# View available images
lxc image list ubuntu:          # Ubuntu official images
lxc image list images:          # Community images
 
# Launch a container
lxc launch ubuntu:26.04 my-container
lxc launch ubuntu:26.04 web-server
 
# Launch a virtual machine (LXD also supports VMs)
lxc launch ubuntu:26.04 my-vm --vm
 
# Container operations
lxc list                        # List all
lxc start my-container          # Start
lxc stop my-container           # Stop
lxc restart my-container        # Restart
lxc delete my-container --force # Delete
lxc info my-container           # Detailed info
 
# Enter a container
lxc exec my-container -- bash
lxc exec my-container -- cat /etc/os-release
 
# File transfer
lxc file push local-file.txt my-container/root/
lxc file pull my-container/etc/hostname .
 
# Snapshots
lxc snapshot my-container snap0
lxc restore my-container snap0
lxc info my-container           # View snapshot list

# CPU limit
lxc config set my-container limits.cpu 2
 
# Memory limit
lxc config set my-container limits.memory 1GB
 
# Disk limit
lxc config device set my-container root size=10GB
 
# Network bandwidth limit
lxc config device set my-container eth0 limits.ingress=100Mbit
lxc config device set my-container eth0 limits.egress=100Mbit

# Create a custom profile
lxc profile create web-server
 
lxc profile set web-server limits.cpu 2
lxc profile set web-server limits.memory 2GB
 
# Launch a container using a profile
lxc launch ubuntu:26.04 web1 --profile default --profile web-server
 
# View the profile
lxc profile show web-server
 
# cloud-init integration
lxc profile set web-server user.user-data - << 'EOF'
#cloud-config
packages:
  - nginx
runcmd:
  - systemctl enable --now nginx
EOF

# Install on all nodes
sudo snap install lxd
sudo snap install microceph
sudo snap install microovn
sudo snap install microcloud
 
# Initialize the cluster on the first node
sudo microcloud init

# microcloud init will guide you through:
# 1. Discovering other nodes on the LAN
# 2. Selecting nodes to join the cluster
# 3. Configuring MicroCeph distributed storage
# 4. Configuring MicroOVN networking
# 5. Configuring the LXD cluster
 
# Verify after initialization
lxc cluster list
sudo microceph status
sudo microovn status

# Launch containers (automatically distributed across cluster nodes)
lxc launch ubuntu:26.04 app1
lxc launch ubuntu:26.04 app2
lxc launch ubuntu:26.04 app3
 
# Launch on a specific node
lxc launch ubuntu:26.04 db1 --target node2
 
# View container distribution
lxc list -c nNtSl
 
# Live-migrate a container
lxc move app1 --target node3

# Install Cockpit
sudo apt install cockpit cockpit-machines -y
 
# Start the service
sudo systemctl enable --now cockpit.socket
 
# Access at https://server-ip:9090
# Manage virtual machines through the web interface
 
# Firewall
sudo ufw allow 9090/tcp

# Install (requires a desktop environment or X11 forwarding)
sudo apt install virt-manager -y
 
# Remote connection (via SSH X11 forwarding)
ssh -X user@server virt-manager