Gonzalo Rivero
Gonzalo Rivero
I am Gonzalo, I live in Salta, a city located in the NW of Argentina. I play the guitar and a little harmonica. I also like to bike.

How to run a VM headless in QEMU-KVM

A client asked me to find a way to keep running an ancient system (from 10+ years ago) in a new server. The old binary packages didn’t work. I couldn’t even compile those packages for our linux in the new server. Then I though in create a Virtual Machine. So this is how to run a VM headless in QEMU-KVM-libvirt-etc.

Virtual Machine creation

The idea was to install the minimal amount of extra software on the server. I also have some time working with gnome-boxes, sometimes alternating with virt-manager.

My idea is do not install those frontends on the server, and launch the virtual machine by command line. On the other hand, I don’t have much time to learn how to do everything from the command line¹.

The solution? I’ve created – with gnome-boxes of course – a Debian 6.0.10 (from 2014) in my own PC, then uploaded the disk image to the server and launch there the virtual machine. By the way, if for some reason you need to deploy some old software you can find Debian CD/DVD images here https://cdimage.debian.org/cdimage/archive/.

Launching the VM headless

Software needed

In order to run the virtual machine with qemu we need to install the virtualization packages. My server happens to work with Debian 11, so I’m installing qemu, kvm and all the stuff with apt-get:

- Advertisement -
apt-get install qemu-kvm libvirt-clients virtinst bridge-utils cpu-checker
that’s some dependencies

After the installation make sure libvirtd is running

systemctl status libvirtd
libvirtd status

If not, you can start it with systemctl start libvirtd.

Creating a new VM with the disk image

With the virt-install command you can import a disk image using this command line:

- Advertisement -
virt-install --import --name <some name for your vm> --memory <desired amount of RAM> --vcpus <#cores> --disk </path/to/your/disk/image.qcow>,bus=sata --os-variant <which os are you running> --network default
How to run a VM headless in QEMU-KVM
a VM is running

You can add the switch –-noautoconsole to run on background. The get the options for the --os-variant switch run:

virt-install --osinfo list

For example, I’m running an ancient Debian distribution:

This is it.

Connecting to your brand new VM

So, I’ve got my VM running… how to connect to do something with that? First I need to know the IP² for this VM. I’m pretty sure there are better ways to do it, but I did it with arp:

192.168.122.x/24 is the default network for my virtual machines

Now is just mater of connect to the virtual machine via ssh:

How to run a VM headless in QEMU-KVM-ssh session
I have to add options to ssh, because is different from the debian 6 days

Now you know how to run a VM headless in qemu-kvm-libvirtd.

VNC access

Alternatively you can enable a VNC console by adding the following to /etc/libvirt/qemu/vm-name.xml, before the end of </devices> section:

<graphics type='vnc' port='-1' autoport='yes' listen='ip' passwd='some password'>

Then restart your VM with

virsh vmname stop
virsh vmname start
virsh vncdisplay vmname

The last line will tell you where to connect, for example if the output is:

127.0.0.1:1

You should connect with a VNC client to 127.0.0.1 and port 5901 (the port is always 5900+display number)

How to run a VM headless in QEMU-KVM-vnc session
VNC session

Notes

¹ as soon as this job ends I definitely I should learn how to do everything from the command line, to save time later

² the screenshots for this article where taken on different computers and on different days, just ignore the different IPs

LEAVE A REPLY

Please enter your comment!
Please enter your name here

Latest articles

Join us on Facebook