Welcome to our guide on OpenNebula KVM Node Installation on Rocky Linux 10 / AlmaLinux 10. You should have a working OpenNebula Front-end server before you proceed since this guide will concentrate on adding a KVM hypervisor to be managed by the OpenNebula Front-end server.

For Ubuntu, check: Install and configure OpenNebula KVM Node on Ubuntu

KVM (Kernel-based Virtual Machine) is the hypervisor for OpenNebula’s Open Cloud Architecture. KVM is a complete virtualization system for Linux. It offers full virtualization, where each Virtual Machine interacts with its own virtualized hardware.

Requirements

  • A working OpenNebula Front-end server
  • Rocky Linux 10 / AlmaLinux 10 installed on the KVM node host
  • CPU with Intel VT or AMD-V features for hardware virtualization support
  • Network connectivity between the Front-end and KVM node
  • Root or sudo access on the KVM node

Note: Rocky Linux 10 / AlmaLinux 10 require x86-64-v3 (Intel Haswell / AMD Excavator or newer) as the minimum CPU architecture. Older processors are no longer supported.

Step 1: Preparation

Set SELinux to Permissive Mode

OpenNebula doesn’t work well with SELinux in enforcing mode. Set it to permissive:

sudo setenforce 0
sudo sed -i 's/^SELINUX=.*/SELINUX=permissive/g' /etc/selinux/config
cat /etc/selinux/config

Verify the change:

getenforce

Rocky Linux 10 / AlmaLinux 10 include updated SELinux policies with new libvirt service types and inverted file context equivalency (/var/run = /run). If you prefer to keep SELinux enforcing, you may need to create custom policies for OpenNebula – but permissive mode is the recommended approach for OpenNebula deployments.

Set Hostname:

sudo hostnamectl set-hostname kvm-node01.example.com

Enable Required Repositories

Rocky Linux 10 / AlmaLinux 10 use dnf as the default package manager. Add the EPEL and CRB (CodeReady Builder) repositories:

sudo dnf install -y epel-release

Enable the CRB repository (some OpenNebula dependencies require it):

repo=$(dnf repolist --disabled | grep -i -e powertools -e crb | awk '{print $1}' | head -1)
sudo dnf config-manager --set-enabled $repo && sudo dnf makecache

Add OpenNebula Repository

Check the OpenNebula Downloads page for the latest version. As of this writing, OpenNebula 7.0 is the current stable release.

Community Edition:

sudo cat << "EOT" > /etc/yum.repos.d/opennebula.repo
[opennebula]
name=OpenNebula Community Edition
baseurl=https://downloads.opennebula.io/repo/7.1/AlmaLinux/$releasever/$basearch
enabled=1
gpgkey=https://downloads.opennebula.io/repo/repo2.key
gpgcheck=1
repo_gpgcheck=1
EOT

Enterprise Edition (requires a subscription token):

sudo cat << "EOT" > /etc/yum.repos.d/opennebula.repo
[opennebula]
name=OpenNebula Enterprise Edition
baseurl=https://<token>@enterprise.opennebula.io/repo/7.1/AlmaLinux/$releasever/$basearch
enabled=1
gpgkey=https://downloads.opennebula.io/repo/repo2.key
gpgcheck=1
repo_gpgcheck=1
EOT

Replace <token> with your customer-specific access credentials.

Refresh the package cache:

sudo dnf makecache

System Update

Update all existing packages and reboot:

sudo dnf -y update
sudo systemctl reboot

Step 2: Install OpenNebula KVM Node

After the reboot, install the KVM node package and restart libvirt:

sudo dnf install -y opennebula-node-kvm

Check the installed package details:

rpm -qi opennebula-node-kvm

Restart libvirt to apply the OpenNebula-provided configuration:

sudo systemctl restart libvirtd
sudo systemctl enable libvirtd

Configure libvirt for oneadmin

Ensure the following lines are present in /etc/libvirt/libvirtd.conf so the oneadmin user can interact with KVM:

unix_sock_group = "oneadmin"
unix_sock_rw_perms = "0777"

Restart libvirtd whenever you make changes:

sudo systemctl restart libvirtd

Verify KVM is working:

virsh -c qemu:///system list

You should see an empty list with no errors.

Step 3: Configure Passwordless SSH

OpenNebula Front-end connects to the hypervisor Hosts using SSH. You must distribute the public key of the oneadmin user from all machines to the file /var/lib/one/.ssh/authorized_keys on all the machines.

When the package was installed on the Front-end, an SSH key was generated and the authorized_keys file populated. We need to create a known_hosts file and sync it to the nodes as well.

On the Front-end

Create the known_hosts file as user oneadmin with all the node names and the Front-end name as parameters:

sudo su - oneadmin
ssh-keyscan <frontend> <node1> <node2> >> /var/lib/one/.ssh/known_hosts

Copy SSH Keys to Nodes

First, set a temporary password for oneadmin on all nodes:

# On each KVM node
sudo passwd oneadmin

Then from the Front-end, copy the .ssh directory:

# On the Front-end as oneadmin
scp -rp /var/lib/one/.ssh <node1>:/var/lib/one/
scp -rp /var/lib/one/.ssh <node2>:/var/lib/one/

Test SSH Connectivity

Test from the Front-end — you should not be prompted for a password:

ssh <node1>
ssh <frontend>

Also verify node-to-node and node-to-frontend SSH works without password prompts, as this is needed for live migration operations.

Step 4: Configure Host Networking

A network connection is needed by the OpenNebula Front-end daemons to access the hosts, manage and monitor them, and transfer Image files. It is highly recommended to use a dedicated network for management purposes.

Important: Rocky Linux 10 / AlmaLinux 10 Networking Changes

Rocky Linux 10 / AlmaLinux 10 have removed legacy ifcfg-rh network scripts entirely. You must use NetworkManager tools for all network configuration:

  • nmcli – command-line interface
  • nmtui – text-based user interface
  • nmstate – declarative network configuration

Network configuration files are now stored in /etc/NetworkManager/system-connections/ (keyfile format). The old /etc/sysconfig/network-scripts/ directory and ifup/ifdown commands are no longer available.

Supported Networking Modes

OpenNebula supports four different networking modes:

  • Bridged – The VM is directly attached to an existing bridge on the hypervisor. Supports security groups and network isolation.
  • VLAN – Virtual Networks implemented through 802.1Q VLAN tagging.
  • VXLAN – Virtual Networks using the VXLAN protocol with UDP encapsulation and IP multicast.
  • Open vSwitch – Similar to VLAN mode but using Open vSwitch instead of a Linux bridge.

Example: Creating a Bridge with NetworkManager

For bridged networking (the most common setup), create a bridge using nmcli:

# Create the bridge
sudo nmcli connection add type bridge con-name br0 ifname br0

# Add the physical interface as a bridge slave
sudo nmcli connection add type ethernet con-name br0-port1 ifname eth0 master br0

# Configure IP addressing on the bridge (static example)
sudo nmcli connection modify br0 ipv4.addresses "192.168.1.100/24"
sudo nmcli connection modify br0 ipv4.gateway "192.168.1.1"
sudo nmcli connection modify br0 ipv4.dns "8.8.8.8,8.8.4.4"
sudo nmcli connection modify br0 ipv4.method manual

# Disable STP if not needed
sudo nmcli connection modify br0 bridge.stp no

# Bring up the bridge
sudo nmcli connection up br0

Replace eth0 with your actual network interface name (check with nmcli device status).

For DHCP:

sudo nmcli connection modify br0 ipv4.method auto

NIC teaming has been removed in Rocky Linux 10 / AlmaLinux 10. Use network bonding instead for link aggregation.

For storage configurations, visit the Open Cloud Storage documentation.

Step 5: Configure Firewall (Optional)

If firewalld is running, allow libvirt traffic:

sudo firewall-cmd --permanent --zone=trusted --add-source=<frontend-ip>/32
sudo firewall-cmd --permanent --add-port=22/tcp
sudo firewall-cmd --reload

Alternatively, for lab/test environments:

sudo systemctl stop firewalld
sudo systemctl disable firewalld

Step 6: Adding a Host to OpenNebula

The final step is registering the KVM node on the OpenNebula Front-end so that OpenNebula can launch VMs on it. This step can be done via the CLI or through Sunstone (the graphical user interface). Follow just one method — they accomplish the same thing.

Adding a Host through Sunstone

  1. Open Sunstone → Infrastructure → Hosts
  2. Click the + button
  3. Select KVM for the type field
  4. Enter the FQDN or IP address of the node in the Hostname field
  5. Go back to the hosts section and confirm it’s in ON state

If the host turns to err state instead of on, check /var/log/one/oned.log. Chances are it’s a problem with SSH.

Adding a Host through the CLI

To add a node to the cloud, run this command as oneadmin on the Front-end:

$ onehost create <node01> -i kvm -v kvm

$ onehost list
  ID NAME            CLUSTER   RVM ALLOCATED_CPU      ALLOCATED_MEM STAT
   1 localhost        default     0       -                  -       init

# After some time — around 1-2 minutes
$ onehost list
  ID NAME            CLUSTER   RVM ALLOCATED_CPU      ALLOCATED_MEM STAT
   0 192.168.70.82    default     0 0 / 1600 (0%)   0K / 94.2G (0%) on

The host should transition to on state within a couple of minutes.

Troubleshooting

Host stuck in err state

Most commonly caused by SSH issues. Verify:

# From the Front-end as oneadmin
ssh <node-ip> hostname

If prompted for a password, the SSH key distribution (Step 3) needs to be revisited.

Check logs

# On the Front-end
cat /var/log/one/oned.log | grep -i <node-hostname>

# On the KVM node
sudo journalctl -u libvirtd

Verify KVM support

egrep -c '(vmx|svm)' /proc/cpuinfo
lsmod | grep kvm

libvirt modular daemons conflict

If libvirt isn’t responding, ensure the legacy monolithic daemon is in use:

sudo systemctl stop virtqemud.socket virtqemud.service
sudo systemctl disable virtqemud.socket virtqemud.service
sudo systemctl enable --now libvirtd

This is the end of the OpenNebula KVM Node Installation on Rocky Linux 10 / AlmaLinux 10 guide. In the next guide, we cover Virtual configurations and Storage.

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