Getting Started with OpenNebula¶

Dependencies¶

The driver requires Python's lxml library to be installed. It also requires an OpenNebula installation running version 4.12 or greater.

Configuration¶

The following example illustrates some of the options that can be set. These parameters are discussed in more detail below.

# Note: This example is for /etc/salt/cloud.providers or any file in the
# /etc/salt/cloud.providers.d/ directory.

my-opennebula-provider:
  # Set up the location of the salt master
  #
  minion:
    master: saltmaster.example.com

  # Define xml_rpc setting which Salt-Cloud uses to connect to the OpenNebula API. Required.
  #
  xml_rpc: http://localhost:2633/RPC2

  # Define the OpenNebula access credentials. This can be the main "oneadmin" user that OpenNebula uses as the
  # OpenNebula main admin, or it can be a user defined in the OpenNebula instance. Required.
  #
  user: oneadmin
  password: JHGhgsayu32jsa

  # Define the private key location that is used by OpenNebula to access new VMs. This setting is required if
  # provisioning new VMs or accessing VMs previously created with the associated public key.
  #
  private_key: /path/to/private/key

  driver: opennebula

Access Credentials¶

The Salt Cloud driver for OpenNebula was written using OpenNebula's native XML RPC API. Every interaction with OpenNebula's API requires a username and password to make the connection from the machine running Salt Cloud to API running on the OpenNebula instance. Based on the access credentials passed in, OpenNebula filters the commands that the user can perform or the information for which the user can query. For example, the images that a user can view with a --list-images command are the images that the connected user and the connected user's groups can access.

Key Pairs¶

Salt Cloud needs to be able to access a virtual machine in order to install the Salt Minion by using a public/private key pair. The virtual machine will need to be seeded with the public key, which is laid down by the OpenNebula template. Salt Cloud then uses the corresponding private key, provided by the private_key setting in the cloud provider file, to SSH into the new virtual machine.

To seed the virtual machine with the public key, the public key must be added to the OpenNebula template. If using the OpenNebula web interface, navigate to the template, then click Update. Click the Context tab. Under the Network & SSH section, click Add SSH Contextualization and paste the public key in the Public Key box. Don't forget to save your changes by clicking the green Update button.

Cloud Profiles¶

Set up an initial profile at either /etc/salt/cloud.profiles or the /etc/salt/cloud.profiles.d/ directory.

my-opennebula-profile:
  provider: my-opennebula-provider
  image: Ubuntu-14.04

The profile can now be realized with a salt command:

salt-cloud -p my-opennebula-profile my-new-vm

This will create a new instance named my-new-vm in OpenNebula. The minion that is installed on this instance will have a minion id of my-new-vm. If the command was executed on the salt-master, its Salt key will automatically be signed on the master.

Once the instance has been created with salt-minion installed, connectivity to it can be verified with Salt:

salt my-new-vm test.version

OpenNebula uses an image --> template --> virtual machine paradigm where the template draws on the image, or disk, and virtual machines are created from templates. Because of this, there is no need to define a size in the cloud profile. The size of the virtual machine is defined in the template.

Change Disk Size¶

You can now change the size of a VM on creation by cloning an image and expanding the size. You can accomplish this by the following cloud profile settings below.

my-opennebula-profile:
  provider: my-opennebula-provider
  image: Ubuntu-14.04
  disk:
    disk0:
      disk_type: clone
      size: 8096
      image: centos7-base-image-v2
    disk1:
      disk_type: volatile
      type: swap
      size: 4096
    disk2:
      disk_type: volatile
      size: 4096
      type: fs
      format: ext3

There are currently two different disk_types a user can use: volatile and clone. Clone which is required when specifying devices will clone an image in open nebula and will expand it to the size specified in the profile settings. By default this will clone the image attached to the template specified in the profile but a user can add the image argument under the disk definition.

For example the profile below will not use Ubuntu-14.04 for the cloned disk image. It will use the centos7-base-image image:

my-opennebula-profile:
  provider: my-opennebula-provider
  image: Ubuntu-14.04
  disk:
    disk0:
      disk_type: clone
      size: 8096
      image: centos7-base-image

If you want to use the image attached to the template set in the profile you can simply remove the image argument as show below. The profile below will clone the image Ubuntu-14.04 and expand the disk to 8GB.:

my-opennebula-profile:
  provider: my-opennebula-provider
  image: Ubuntu-14.04
  disk:
    disk0:
      disk_type: clone
      size: 8096

A user can also currently specify swap or fs disks. Below is an example of this profile setting:

my-opennebula-profile:
  provider: my-opennebula-provider
  image: Ubuntu-14.04
  disk:
    disk0:
      disk_type: clone
      size: 8096
    disk1:
      disk_type: volatile
      type: swap
      size: 4096
    disk2:
      disk_type: volatile
      size: 4096
      type: fs
      format: ext3

The example above will attach both a swap disk and a ext3 filesystem with a size of 4GB. To note if you define other disks you have to define the image disk to clone because the template will write over the entire 'DISK=[]' template definition on creation.

Required Settings¶

The following settings are always required for OpenNebula:

my-opennebula-config:
  xml_rpc: http://localhost:26633/RPC2
  user: oneadmin
  password: JHGhgsayu32jsa
  driver: opennebula

my-opennebula-config:
  private_key: /path/to/private/key

Listing Images¶

Images can be queried on OpenNebula by passing the --list-images argument to Salt Cloud:

salt-cloud --list-images opennebula

Listing Locations¶

In OpenNebula, locations are defined as hosts. Locations, or "hosts", can be querried on OpenNebula by passing the --list-locations argument to Salt Cloud:

salt-cloud --list-locations opennebula

Listing Sizes¶

Sizes are defined by templates in OpenNebula. As such, the --list-sizes call returns an empty dictionary since there are no sizes to return.

Additional OpenNebula API Functionality¶

The Salt Cloud driver for OpenNebula was written using OpenNebula's native XML RPC API. As such, many --function and --action calls were added to the OpenNebula driver to enhance support for an OpenNebula infrastructure with additional control from Salt Cloud. See the OpenNebula function definitions for more information.

Access via DNS entry instead of IP¶

Some OpenNebula installations do not assign IP addresses to new VMs, instead they establish the new VM's hostname based on OpenNebula's name of the VM, and then allocate an IP out of DHCP with dynamic DNS attaching the hostname. This driver supports this behavior by adding the entry fqdn_base to the driver configuration or the OpenNebula profile with a value matching the base fully-qualified domain. For example:

# Note: This example is for /etc/salt/cloud.providers or any file in the
# /etc/salt/cloud.providers.d/ directory.

my-opennebula-provider:
  [...]
  fqdn_base: corp.example.com
  [...]