Virtualization Features in Cozystack on Cozystack

Virtual Machine

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A Virtual Machine (VM) simulates computer hardware, enabling various operating systems and applications to run in an isolated environment.

Deployment Details

The virtual machine is managed and hosted through KubeVirt, allowing you to harness the benefits of virtualization within your Kubernetes ecosystem.

Docs: KubeVirt User Guide
GitHub: KubeVirt Repository

Accessing virtual machine

You can access the virtual machine using the virtctl tool:

Virtual Machine Disk

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A Virtual Machine Disk

Parameters

Common parameters

Name	Description	Type	Value
`source`	The source image location used to create a disk.	`object`	`{}`
`source.image`	Use image by name.	`*object`	`null`
`source.image.name`	Name of the image to use (uploaded as “golden image” or from the list: `ubuntu`, `fedora`, `cirros`, `alpine`, `talos`).	`string`	`""`
`source.upload`	Upload local image.	`*object`	`null`
`source.http`	Download image from an HTTP source.	`*object`	`null`
`source.http.url`	URL to download the image.	`string`	`""`
`optical`	Defines if disk should be considered optical.	`bool`	`false`
`storage`	The size of the disk allocated for the virtual machine.	`quantity`	`5Gi`
`storageClass`	StorageClass used to store the data.	`string`	`replicated`

Creating and Using Named VM Images

Mon, 01 Jan 0001 00:00:00 +0000

Golden images in Cozystack allow administrators to prepare named operating system images that users can later reuse when creating virtual machines.
This guide explains the benefits of golden images, how to create them, and how to use them when deploying VMs.

By default, every time a user creates a virtual machine, Cozystack downloads the required image from its source URL.
This can become a bottleneck when multiple VMs are created in quick succession.
Golden images solve this problem by caching the image locally, eliminating repeated downloads and speeding up deployment.

Backup and Recovery

Mon, 01 Jan 0001 00:00:00 +0000

Cluster backup strategies and BackupClasses are configured by cluster administrators. If your tenant does not have a BackupClass yet, ask your administrator to follow the Velero Backup Configuration guide to set up storage, strategies, and BackupClasses.

This guide covers backing up and restoring VMInstance and VMDisk resources as a tenant user: running one-off and scheduled backups, checking backup status, and restoring from a backup using RestoreJobs.

Cozystack uses Velero under the hood for backup storage and volume snapshots.

Cloneable Virtual Machines

Mon, 01 Jan 0001 00:00:00 +0000

To create a cloneable VM, you will need to create a VMDisk and a VMInstance. This guide uses an ubuntu base image as an example.

Create VMDisk

apiVersion: apps.cozystack.io/v1alpha1
kind: VMDisk
metadata:
 name: ubuntu-source
 namespace: tenant-root
spec:
 optical: false
 source:
 http:
 url: https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img
 storage: 20Gi
 storageClass: replicated

Since expanding a disk can be complicated, we recommend creating it with extra space to accommodate future growth.

Create VMInstance

Running VMs with GPU Passthrough and vGPU

Mon, 01 Jan 0001 00:00:00 +0000

This section demonstrates how to deliver GPU access to virtual machines (VMs) on Cozystack. It covers two flows: GPU passthrough (one whole physical GPU bound to a single VM via vfio-pci) and NVIDIA vGPU (one physical GPU sliced into multiple virtual GPUs via SR-IOV, with each VF passed to a different VM). The passthrough flow comes first; jump to GPU Sharing for Virtual Machines (vGPU) for the vGPU walk-through.

By default, to provision a GPU Passthrough, the GPU Operator will deploy the following components:

Running Windows VMs in Cozystack

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Cozystack can run Windows virtual machines. This guide explains the prerequisites and steps required to boot up a virtual machine running Windows OS.

Prerequisites

Windows installation ISO image.
Virtio drivers ISO image.
KubeVirt client virtctl installed in your local environment and configured for your tenant’s namespace.
Cozystack version v0.34.2 or later.

Installation

Creating a virtual machine running Windows OS starts with creating VMDisk objects and continues with creating a VMInstance.

1. Create VMDisk objects

You need three disks:

Running MikroTik RouterOS in Cozystack

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

MikroTik RouterOS ISO (CHR or NPK install image), for example, mikrotik-7.19.3.iso.
A free static IP or DHCP on the connected tenant network.
KubeVirt client virtctl installed in your local environment and configured for your tenant’s namespace.
Cozystack version v0.34.2 or later.

Installation

1. Prepare disks

You need two disks:

Installation ISO – optical.
System disk – non‑optical.

apiVersion: apps.cozystack.io/v1alpha1
kind: VMDisk
metadata:
 name: mikrotik-iso
spec:
 source:
 http:
 url: https://download.mikrotik.com/routeros/7.19.3/mikrotik-7.19.3.iso
 optical: true
 storage: 1Gi
 storageClass: replicated
---
apiVersion: apps.cozystack.io/v1alpha1
kind: VMDisk
metadata:
 name: mikrotik-system
spec:
 optical: false
 storage: 1Gi
 storageClass: replicated

2. Create the VMInstance

RouterOS does not require a special instance profile. Use a lightweight Linux profile such as ubuntu with a small instance type such as u1.medium:

Migrating Virtual Machines from Proxmox

Mon, 01 Jan 0001 00:00:00 +0000

This guide describes the process of migrating virtual machines from Proxmox VE to Cozystack by exporting VM disk images and uploading them to the target environment.

Note: Migration is performed by exporting VM disks to files and uploading them to Cozystack. VM state and snapshots are not preserved during migration.

Prerequisites

Before starting the migration, ensure you have:

KubeVirt client virtctl installed on your local machine:
- Installation guide: KubeVirt User Guide - Virtctl Client Tool
Upload proxy access configured in your Cozystack cluster:

Virtual Machine Resources

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Each virtual machine has these two configuration settings:

instanceType defines the resourced provided to the Virtual Machine.
instanceProfile defines the set of preferences for Virtual Machines, according to the OS being used.

Instance Type Resources

Reference table

The following instancetype resources are provided by Cozystack:

Name	vCPUs	Memory
cx1.2xlarge	8	16Gi
cx1.4xlarge	16	32Gi
cx1.8xlarge	32	64Gi
cx1.large	2	4Gi
cx1.medium	1	2Gi
cx1.xlarge	4	8Gi
gn1.2xlarge	8	32Gi
gn1.4xlarge	16	64Gi
gn1.8xlarge	32	128Gi
gn1.xlarge	4	16Gi
m1.2xlarge	8	64Gi
m1.4xlarge	16	128Gi
m1.8xlarge	32	256Gi
m1.large	2	16Gi
m1.xlarge	4	32Gi
n1.2xlarge	16	32Gi
n1.4xlarge	32	64Gi
n1.8xlarge	64	128Gi
n1.large	4	8Gi
n1.medium	4	4Gi
n1.xlarge	8	16Gi
o1.2xlarge	8	32Gi
o1.4xlarge	16	64Gi
o1.8xlarge	32	128Gi
o1.large	2	8Gi
o1.medium	1	4Gi
o1.micro	1	1Gi
o1.nano	1	512Mi
o1.small	1	2Gi
o1.xlarge	4	16Gi
rt1.2xlarge	8	32Gi
rt1.4xlarge	16	64Gi
rt1.8xlarge	32	128Gi
rt1.large	2	8Gi
rt1.medium	1	4Gi
rt1.micro	1	1Gi
rt1.small	1	2Gi
rt1.xlarge	4	16Gi
u1.2xlarge	8	32Gi
u1.2xmedium	2	4Gi
u1.4xlarge	16	64Gi
u1.8xlarge	32	128Gi
u1.large	2	8Gi
u1.medium	1	4Gi
u1.micro	1	1Gi
u1.nano	1	512Mi
u1.small	1	2Gi
u1.xlarge	4	16Gi

U Series

The U Series is quite neutral and provides resources for general purpose applications.