Lightweight Linux Hypervisor

There is a variaty of options and tools to provision VMs on linux, I personally prefer this method over installing other hypervisors like: vmware or virtualbox, because they are really bloated, and heavy softwares and it's a bit hard to set up on linux, especially if you are using a DIY distros like arch or gentoo. Instead we are going to use kvm which is a kernel based VM, qemu which is quick emulator that will interact with kvm, libvirt a lib that exports apis to interact with qemu/kvm, finally the GUI interface virt-manager wich we will be using most of the time to set up and start our VMs.

1. Installation

First we need to install the required utilities:

pacman -Sy --needed \
  qemu \
  dhclient \
  virt-viewer \
  libvirt \
  dnsmasq \
  dmidecode \
  ebtables \
  virt-install \
  virt-manager \
  bridge-utils

we don't need to install kvm because it is part of the kernel.

2. Permissions

Communication between virt-manager and libvirt is going through polkit, When using qemu:///system. So you need to have the correct privileges.

P.S: Polkit provides an organized way for non-privileged processes to communicate with privileged ones.

to have permission you need to edit /etc/polkit-1/rules.d/50-libvirt.rules

/* Allow users in wheel group to manage the libvirt
daemon without authentication */
polkit.addRule(function(action, subject) {
    if (action.id == "org.libvirt.unix.manage" &&
        subject.isInGroup("wheel")) {
            return polkit.Result.YES;
    }
});

the restart polkit:

doas systemctl restart polkit

now polkit will allow access for wheel group, so you should add yourself to it:

doas usermod -aG wheel `id -u`

3. Usage

you should be ready now, first we need to start libvirtd:

doas systemctl start libvirtd

finally you can start the gui:

virt-manager

the interface is clear enough if you ever setup a VM before.

if you don't like gui you can use a cli:

virt-install \
  --name archlinux \
  --ram 2048 \
  --disk path=/var/lib/libvirt/images/arch.qcow2,size=8 \
  --vcpus 2 \
  --os-type linux \
  --os-variant generic \
  --console pty,target_type=serial \
  --cdrom ~/storage/archlinux-2020.09.01-x86_64.iso

BTW you can find all your VMs images in /var/lib/libvirt/images.

to clone existing VM you can use virt-clone:

virt-clone \
  --original arch \
  --name arch-clone \
  --file /var/lib/libvirt/images/arch_clone.qcow2