Install OpenNebula KVM Node on Ubuntu 20.04|18.04|16.04

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Welcome to our guide on How to install and configure OpenNebula KVM Node on Ubuntu 20.04|18.0416.04 LTS. Our last article was on  How to Install OpenNebula Front-end on Ubuntu. Before you can proceed with this guide, you should have working OpenNebula Front-end server which can be installed from the link shared.

For CentOS 7, check OpenNebula KVM Node Installation on CentOS 7

KVM (Kernel-based Virtual Machine) is an Open Source hypervisor for OpenNebula’s Open Cloud Architecture. KVM is a complete virtualization software for Linux where each Virtual Machine interacts with its own virtualized hardware.

Install OpenNebula KVM Node on Ubuntu 20.04|18.04|16.04

The KVM Nodes (physical hosts) should have CPU with Intel VT or AMD’s AMD-V features, in order to support virtualization. KVM’s Preparing to use KVM guide will clarify any doubts you may have regarding if your hardware supports KVM.

Step 1: Add the OpenNebula repository

Import OpenNebula Repository Key:

wget -q -O- | sudo apt-key add -

Then add OpenNebula repository to your Ubuntu 20.04|18.04|16.04 LTS server. Please check the recent version of OpenNebula as you install.

sudo apt update

Add the repository to the system:

### Ubuntu 20.04 ###
echo "deb stable opennebula" | sudo tee /etc/apt/sources.list.d/opennebula.list

### Ubuntu 18.04 ###
echo "deb stable opennebula" | sudo tee /etc/apt/sources.list.d/opennebula.list

### Ubuntu 16.04 ###
echo "deb stable opennebula" | sudo tee /etc/apt/sources.list.d/opennebula.list

Step 2. Install OpenNebula KVM packages

Execute the following commands to install the node package and restart libvirt to use the OpenNebula provided configuration file:

sudo apt update
sudo apt install opennebula-node

Accept the installation using the key:

The following packages will be upgraded:
1 upgraded, 181 newly installed, 0 to remove and 11 not upgraded.
Need to get 57.5 MB of archives.
After this operation, 244 MB of additional disk space will be used.
Do you want to continue? [Y/n] y

You should have these line under /etc/libvirt/libvirtd.conf for oneadmin to work well with KVM:

$ sudo vim /etc/libvirt/libvirtd.conf
unix_sock_group = "oneadmin"
unix_sock_rw_perms = "0777"

Always restart libvirtd when you make a change.

sudo systemctl restart libvirtd.service libvirt-bin.service

For further configuration, check the specific guide: KVM.

Step 3: Configure Passwordless SSH

OpenNebula Front-end connects to the hypervisor Hosts using SSH. You must distribute the public key of the useroneadmin from all machines to the file /var/lib/one/.ssh/authorized_keyson all the machines.   When the package was installed in the Front-end, an SSH key was generated and the authorized_keys populated. We need to create a known_hosts file and sync it as well to the nodes.   To create the known_hosts file, we have to execute this command as user oneadmin in the Front-end with all the node names and the Front-end name as parameters:

$ sudo su - oneadmin
$ ssh-keyscan     ... >> /var/lib/one/.ssh/known_hosts

Now we need to copy the directory /var/lib/one/.ssh to all the nodes. You can reset the password for the oneadmin user on all nodes.

sudo passwd oneadmin

Then on Front-end node, run

$ scp -rp /var/lib/one/.ssh :/var/lib/one/
$ scp -rp /var/lib/one/.ssh :/var/lib/one/

Test ssh from Front-end, you should not be prompted for a password:

$ ssh 
$ ssh 


Generate keys:

$ ssh-keyscan >> /var/lib/one/.ssh/known_hosts

Where is the IP address of Frontend Node and is the IP Address of first KVM node.

Copy from Frontend to KVM node:

$ scp -rp /var/lib/one/.ssh
[email protected]'s password: 
authorized_keys                         100%  400   133.7KB/s   00:00    
id_rsa                                  100% 1679   378.2KB/s   00:00    
known_hosts                             100% 1330   486.0KB/s   00:00                              100%  400   251.8KB/s   00:00

Test SSH from the Frontend:

[email protected]:~$ ssh
[email protected]:~$

Step 4: Configure Host Networking

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

network-02OpenNebula supports four different networking modes:

  • Bridged. The Virtual Machine is directly attached to an existing bridge in the hypervisor. This mode can be configured to use security groups and network isolation.
  • VLAN. Virtual Networks are implemented through 802.1Q VLAN tagging.
  • VXLAN. Virtual Networks implements VLANs using the VXLAN protocol that relies on a UDP encapsulation and IP multicast.
  • Open vSwitch. Similar to the VLAN mode but using an Open vSwitch instead of a Linux bridge.

Documentation for each is provided on the links. My setup uses Bridged networking. I have three bridges on compute hosts, for storage, a private network, and public data.

For storage configurations, visit Open Cloud Storage

Step 5: Adding a Host to OpenNebula

The final step is Adding a Host to OpenNebula. The node is being registered on the OpenNebula Front-end so that OpenNebula can launch VMs on it. This step can be done in the CLI or in Sunstone, the graphical user interface. Follow just one method, not both, as they accomplish the same.

Adding a Host through Sunstone

Open the Sunstone >  Infrastructure -> Hosts. Click on the + button. Select KVM for type field.


The fill in the fqdn or IP address of the node in the Hostname field.


Go back to the hosts’ section and confirm it’s in ON state.



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

Adding a Host through the CLI

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

Create using:

$ onehost create  -i kvm -v kvm

Then check added hosts after few minutes.

$ onehost list
   0   default     0       0 / 200 (0%)     0K / 3.9G (0%) on

This is the end of OpenNebula KVM Node Installation on Ubuntu 20.04|18.04|16.04. In the next guide, we’ll cover Virtual configurations and Storage.


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