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OpenNebula 4.4

OpenNebula is a mature and stable Cloud Management Software that scales from a single node cloud to thousands of physical nodes. It can be used to build private, public or hybrid clouds. This guide will help you geting started with building an OpenNebula cloud on CentOS.

Throughout the installation there are two separate roles: Frontend and Nodes. The Frontend server will execute the OpenNebula services, and the Nodes will be used to execute virtual machines. Please note that it is possible to follow this guide with just one host combining both the Frontend and Nodes roles in a single server. However it is recommended execute virtual machines in hosts with virtualization extensions. To test if your host supports virtualization extensions, please run:

grep -E 'svm|vmx' /proc/cpuinfo

If you don't get any output you probably don't have virtualization extensions supported/enabled in your server.

Command line tools and other resources within OpenNebula are refered to as 'one' tools.

1. Package Layout

OpenNebula provides these main packages:

Additionally opennebula-common and opennebula-ruby exist but they're intended to be used as dependencies. opennebula-occi, which is RESTful service to manage the cloud, is included in the opennebula-sunstone package.

2. Installation in the Frontend

2.1. Install the repo

<!> TODO: Repo information.

Ensure that the repo is setup cleanly by running:

# yum repolist

2.2. Install the required packages

A complete install of OpenNebula will have at least both opennebula-server and opennebula-sunstone package:

# yum install opennebula-server opennebula-sunstone

2.3. Configure and Start the services

There are two main processes that must be started, the main OpenNebula daemon: oned, and the graphical user interface: sunstone.

Sunstone listens only in the loopback interface by default for security reasons. To change it edit /etc/one/sunstone-server.conf and change :host: to :host:

Now we can start the services:

# service opennebula start
# service opennebula-sunstone start

2.4. Configure NFS

<!> Skip this section if you are using a single server for both the frontend and worker node roles.

Export /var/lib/one/ from the frontend to the worker nodes. To do so add the following to the /etc/exports file in the frontend:

/var/lib/one/ *(rw,sync,no_subtree_check,root_squash)

Refresh the NFS exports by doing:

# service rpcbind restart
# service nfs restart    

2.5. Configure SSH Public Key

OpenNebula will need to SSH passwordlessly from any node (including the frontend) to any other node.

Add the following snippet to ~/.ssh/config as oneadmin so it doesn't prompt to add the keys to the known_hosts file:

# su - oneadmin
$ cat << EOT > ~/.ssh/config
Host *
    StrictHostKeyChecking no
    UserKnownHostsFile /dev/null
$ chmod 600 ~/.ssh/config

3. Installation in the Nodes

3.1. Install the repo

<!> TODO: Repo information.

Ensure that the repo is setup cleanly by running:

# yum repolist

3.2. Install the required packages

# yum install opennebula-node-kvm

Start the required services:

# service messagebus start
# service libvirtd start    

3.3. Configure the Network

<!> Backup all the files that are modified in this section before making changes to them.

You will need to have your main interface, typically eth0, connected to a bridge. The name of the bridge should be the same in all nodes.

To do so, substitute /etc/sysconfig/network-scripts/ifcfg-eth0 with:


And add a new /etc/sysconfig/network-scripts/ifcfg-br0 file.

If you were using DHCP for your eth0 interface, use this template:


If you were using a static IP address use this other template:


After these changes, restart the network:

# service network restart

3.4. Configure NFS

<!> Skip this section if you are using a single server for both the frontend and worker node roles.

Mount the datastores export. Add the following to your /etc/fstab:  /var/lib/one/  nfs   soft,intr,rsize=8192,wsize=8192,noauto

<!> Replace with the IP of the frontend.

Mount the NFS share:

# mount /var/lib/one/

4. Basic Usage

<!> All the operations in this section can be done using Sunstone instead of the command line. Point your browser to: http://frontend:9869.

The default password for the oneadmin user can be found in ~/.one/one_auth which is randomly generated on every installation.

To interact with OpenNebula, you have to do it from the oneadmin account in the frontend. We will assume all the following commands are performed from that account. To login as oneadmin execute su - oneadmin.

4.1. Adding a Host

To start running VMs, you should first register a worker node for OpenNebula.

Issue this command for each one of your nodes. Replace localhost with your node's hostname.

$ onehost create localhost -i kvm -v kvm -n dummy

Run onehost list until it's set to on. If it fails you probably have something wrong in your ssh configuration. Take a look at /var/log/one/oned.log.

4.2. Adding virtual resources

Once it's working you need to create a network, an image and a virtual machine template.

To create networks, we need to create first a network template file mynetwork.one that contains:

NAME = "private"

BRIDGE = br0

LEASES = [ IP= ]
LEASES = [ IP= ]
LEASES = [ IP= ]    

<!> Replace the leases with free IPs in your host's network. You can add any number of leases.

Now we can move ahead and create the resources in OpenNebula:

$ onevnet create mynetwork.one

$ oneimage create --name "CentOS-6.4_x86_64" \
    --path "http://us.cloud.centos.org/i/one/c6-x86_64-20130910-1.qcow2.bz2" \
    --driver qcow2 \
    --datastore default

$ onetemplate create --name "CentOS-6.4" --cpu 1 --vcpu 1 --memory 512 \
    --arch x86_64 --disk "CentOS-6.4_x86_64" --nic "private" --vnc \

You will need to wait until the image is ready to be used. Monitor its state by running oneimage list.

In order to dynamically add ssh keys to Virtual Machines we must add our ssh key to the user template, by editing the user template:

$ EDITOR=vi oneuser update oneadmin

Add a new line like the following to the template:


Substitute the value above with the output of cat ~/.ssh/id_dsa.pub.

4.3. Running a Virtual Machine

To run a Virtual Machine, you will need to instantiate a template:

$ onetemplate instantiate "CentOS-6.4" --name "My Scratch VM"

Execute onevm list and watch the virtual machine going from PENDING to PROLOG to RUNNING. If the vm fails, check the reason in the log: /var/log/one/<VM_ID>/vm.log.

5. Support and Troubleshooting

Logs are located in /var/log/one. Be sure to check that in order to troubleshoot. If you need assistance, upstream can help you through their main channels of support.

6. Further information

2023-09-11 07:19