Virtualization

Ubuntu has a virtualization suite that lets you set up a server that is a centrally available server you can run VMs on:

  • Kernel-based VM (KVM) and Quick Emulator (QEMU)
    • KVM is built into the kernal that handles low-level instructins in the kernel to separate host from guest
    • KVM can run at near native speeds
    • QEMU emulates hardware components found in physical servers
  • Lets machine run VMs without a 3rd party product like VirtualBox (a centrally available VM server)
    • Can only run VirtualBox or KVM/QEMU, not both at the same time. CPU can’t handle both
  • Virtual Machine Manager is a GUI that helps you perform VM admin tasks - virt-manager
    • Can manage local and remote KVM servers
  • KVM machines are assigned IP addr on 192.168.122.0/24 network
    • Get IP from internal DHCP server, between 192.168.122.2 - 192.168.122.254
    • Can SSH into computer from workstation, set up bridging to get vm to connect directly to your network

KVM/QEMU Installation

egrep -c '(vmx|svm)' /proc/cpuinfo          # check whether cpu supports virtualization extensions
24                                          # more than one means it supports

# --- Installation --- #
# Configure the server, setup workstation to connect to server, workstation to manage virtualization: 
apt install bridge-utils libvirt-clients          # 1. Install libvirt packages to make kvm/qemu work
                         libvirt-daemon-system
                         qemu-system-x86
systemctl status libvirtd                         # 2. check service status
systemctl stop libvirtd                           # 3. stop service for add'l configuration
cat /etc/group | grep kvm                         # 4. verify kvm and libvirtd groups were added
cat /etc/group | grep libvirt
usermod -aG kvm <username>                        # 5. add user to groups
usermod -aG libvirt <username>
# 6. might have to log out and log in to start group memberships
chown :kvm /var/lib/libvirt/images                # 7. give group access to access data in ../images
chmod g+rw /var/lib/libvirt/images                # 8. give rw perms to kvm group
systemctl start libvirtd                          # 9. restart service
apt install ssh-askpass virt-manager              # 10. install GUI for admin tasks

Virtual Machine Manager setup

  1. Open Virtual Machine Manager:
    1. Either search in Applications, or enter virt-manager on command line
  2. Select File > Add Connection to create a new connection to the VM server.
  3. Complete the info in the window. For remote hosts, connect with SSH and add the host info. For a local KVM server, select Autoconnect.

Create a storage pool

Create a new storage pool to store our ISO files:

  1. In Virtual Machine Manager, right-click the connection and select Details.
  2. Select the Storage tab.
  3. Select the green plus symbol at the bottom-left of the screen.
  4. Enter the following info:
    • Name: ISO
    • Target Path: /var/lib/libvirt/images/ISO
  5. Select Finish
  6. Update permissions to the target path directory:
    chown root:kvm /var/lib/libvirt/images/ISO
chmod g+rw /var/lib/libvirt/images/ISO
  7. Move ISO files to the target path so the VM server can create VMs with it.

Create a VM

  1. In Virtual Machine Manager, right-click the server and select New.
  2. Leave Local install media selected and select Forward.
  3. Select Browse to select the /var/lib/libvirt/images/ISO storage pool. Highlight the ISO and select Choose Volume. Select Forward.
  4. Allocate RAM and CPU:
    • 2048MB should be enough RAM
    • 2 CPUs is plenty
  5. Allocate disk space. 20GB is enough for most test machines.
  6. Name the VM and select Finish.

Bridging the network

Lets you receive an IP from the DHCP server on your network instead of internal KVM DHCP:

  • Good if you’re setting up a VM server on your network
  • Every VM can be connected to and treated as a regular machine on the network, with the main DHCP server as the source of truth
  • Bridging generally works on wired network cards, and does not work on wireless network cards
    • backup your netplan file before making changes!

Cloning

Create a VM, configure it, then convert it into a template for all VMs of the same operating system:

  • KVM doesn’t have a templating feature, but you can still configure a VM, name it *-template, then clone it
  1. Right-click a stopped VM and select Clone.
  2. Make sure the ‘clone this disk’ option is selected.
  3. Select Clone.

Managing VMs from commmand line

Use virsh suite of commands to manage VMs if GUI isn’t available:

virsh list                    # list running VMs
virsh list --all              # list all VMs
virsh start <vm-name>         # start VM
virsh shutdown <vm-name>      # shutdown VM
virsh suspend <vm-name>       # pause VM
virsh resume <vm-name>        # unpause VM
virsh destroy <vm-name>       # stop VM immediately
virsh undefine <vm-name>      # deletes a VM, but not associated files
                              # must delete disk files from /var/lib/libvirt/images
virsh net-dhcp-leases default

Static IP addresses

Add the static IP config to the default network xml file so the DHCP server can assign the static ip:

virsh net-dhcp-leases default                         # view all dhcp leases on default network

# add static IP to xml config file
virsh net-update default add ip-dhcp-host "<host mac='<mac-addr>' name='<hostname>' ip='<ip-addr>' />" --live --config
# delete static IP
virsh net-update default delete ip-dhcp-host "<host mac='<mac-addr>' name='<hostname>' ip='<ip-addr>' />" --live --config

virsh net-list
virsh net-dumpxml default
virsh dumpxml <vm-name> | grep -i '<mac'      # get mac addr
virsh net-edit <network-name>                 # edit network config