Creating Debian VM on a local server via CLI
Need a Debian VM running locally? Here’s how you can create one on your server, just like you would in the cloud of your choice.
Introduction
Let’s face it, spinning up a VM in the cloud for some specific tasks can be overkill, not to mention potentially costly. Sometimes, you just need a VM right here, right now, running locally on your machine or a local server.
Usually, if I need a linux VM to test something locally, I would use multipass, which allows you to quickly create an Ubuntu VM. I should write a post about multipass; it’s a very useful tool for creating local Ubuntu VMs. Unfortunately, multipass doesn’t support Debian 😞, only Ubuntu I believe.
For a specific use case, I needed a Debian VM and I wanted to run it on my local server. And by “server,” I’m talking about a not-too-old laptop, with 32GB of RAM running Ubuntu. The goal was CLI all the way – no GUI needed, for maximum automation potential.
TL;DR
Just need the commands to quickly spin that Debian VM on your local server? Head directly to the Summary section.
Prerequisites
You need to have QEMU, libvirt, and virsh installed on your server. When writing this post, I already had these tools installed on my server, so I didn’t need to install them. You can check if you have them installed by running the following commands:
qemu-system-x86 --version
qemu-img version 8.2.2 (Debian 1:8.2.2+ds-0ubuntu1.6)
Copyright (c) 2003-2023 Fabrice Bellard and the QEMU Project developers
virsh --version
10.0.0
Otherwise, you will have to install the packages, which should look like this 1:
sudo apt update
sudo apt install qemu-system-x86 libvirt-daemon-system libvirt-clients virtinst
Deploy the Debian VM
Download the Debian image
Thinking about starting with a clean install, I attempted to download the latest iso, but I realised that this is the format for the installer, not the image. With this in mind, I then downloaded the qcow2 nocloud image from the Debian website.
curl -LO https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-nocloud-amd64.qcow2
Resize the image
Now, the downloaded image comes in at a compact 3GB. That’s fine for a minimal setup, but if you’re planning to do anything substantial inside the VM, you’ll quickly run out of space. Let’s resize it to something more practical, like 30GB in our case.
qemu-img info debian-12-nocloud-amd64.qcow2
image: debian-12-nocloud-amd64.qcow2
file format: qcow2
virtual size: 3 GiB (3221225472 bytes)
disk size: 397 MiB
cluster_size: 65536
Format specific information:
compat: 1.1
compression type: zlib
lazy refcounts: false
refcount bits: 16
corrupt: false
extended l2: false
Child node '/file':
filename: debian-12-nocloud-amd64.qcow2
protocol type: file
file length: 397 MiB (416745984 bytes)
disk size: 397 MiB
Using qemu-img, let’s resize the image to 30GB:
qemu-img resize debian-12-nocloud-amd64.qcow2 30G
Image resized.
You can confirm you now have a 30GB image:
qemu-img info debian-12-nocloud-amd64.qcow2
image: debian-12-nocloud-amd64.qcow2
file format: qcow2
virtual size: 30 GiB (32212254720 bytes)
[...]
Create the VM
With our image prepped, it’s time to bring the VM to life! We’ll use virt-install for this. You could use a raw qemu command directly, but virt-install wraps things up nicely and I’ve used virsh tools before, so it feels like a comfortable choice for this.
sudo virt-install \
--name debipf \
--memory 8192 \
--vcpus 4 \
--disk path=debian-12-nocloud-amd64.qcow2,device=disk,bus=virtio \
--network network=default,model=virtio \
--graphics none \
--os-variant debian12 \
--accelerate \
--import
Let’s break down the options used in the command virt-install:
--name debipf: This option sets the name of your VM--memory 8192: Memory in MB - 8192MB = 8GB RAM for the VM. Adjust as needed!--vcpus 4: This is the number of virtual CPUs to allocate to the VM.--disk path=debian-12-nocloud-amd64.qcow2,device=disk,bus=virtio: Points to our downloaded and resized qcow2 image, and tells the VM to treat it as a virtio disk.--network network=default,model=virtio: Sets up networking using the ‘default’ network and virtio again for network interface efficiency.--graphics none: This disables the graphical console for the VM, we’re going headless.--os-variant debian12: Helps virt-install optimize settings for Debian 12.--accelerate: Use hardware virtualization extensions for better performance--import: Tells virt-install we are importing an existing disk image, not creating a new one from scratch.
After a few seconds, you should see the Debian system booting up and the login prompt appearing. You can now log in and start using your Debian VM, using username root and no password.
[ OK ] Finished systemd-update-ut… - Record Runlevel Change in UTMP.
Debian GNU/Linux 12 localhost ttyS0
localhost login: root
Linux localhost 6.1.0-31-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.128-1 (2025-02-07) x86_64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Sat Mar 15 01:29:56 UTC 2025 on ttyS0
root@localhost:~#
Expand the filesystem
Almost there! Remember we resized the disk image to 30GB? Well, the filesystem inside the VM still thinks it’s only 3GB. The last crucial step is to expand the filesystem to actually use that extra space we allocated.
sudo apt update && sudo apt install -y cloud-guest-utils
growpart /dev/vda 1
CHANGED: partition=1 start=262144 old: size=6027264 end=6289407 new: size=62652383 end=62914526
Connect to the VM using the console
Need to get into the VM’s console directly? No problem, virsh console to the rescue:
sudo virsh console debipf
Enable SSH access
If you want to connect to the VM via SSH, you will need to install the openssh-server package:
sudo apt update && sudo apt install -y openssh-server
You just need to copy your SSH public key to the authorized_keys file, and you will be able to connect to your VM via SSH:
echo "ssh-rsa XXX..." >> /root/.ssh/authorized_keys
Delete the VM
If you want to delete the VM, you can use the following command:
sudo virsh destroy debipf && sudo virsh undefine debipf --remove-all-storage
Summary
So there you have it! A Debian VM up and running locally via the command line. Quick, efficient, and perfect for local testing. Enjoy!
From the host
curl -LO https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-nocloud-amd64.qcow2
qemu-img info debian-12-nocloud-amd64.qcow2
qemu-img resize debian-12-nocloud-amd64.qcow2 30G
qemu-img info debian-12-nocloud-amd64.qcow2
sudo virt-install \
--name debipf \
--memory 8192 \
--vcpus 4 \
--disk path=debian-12-nocloud-amd64.qcow2,device=disk,bus=virtio \
--network network=default,model=virtio \
--graphics none \
--os-variant debian12 \
--accelerate \
--import
From the VM (guest)
# Optional: connect to the VM via console
# sudo virsh console debipf
# enter the username
root
# expand the filesystem
sudo apt update && sudo apt install -y cloud-guest-utils openssh-server
growpart /dev/vda 1
# add your ssh public key
echo "ssh-rsa XXXXX..." >> /root/.ssh/authorized_keys
-
Your mileage may vary, as this setup was done on an existing Ubuntu server and not a fresh install. You might need additional packages or different versions depending on your system configuration. This guide is based on an x86_64 architecture. ↩