OpenNebula

The OpenNebula (ON) datasource supports the contextualization disk.

See contextualization overview, contextualizing VMs and network configuration in the public documentation for more information.

OpenNebula’s virtual machines are contextualized (parametrized) by CD-ROM image, which contains a shell script context.sh with custom variables defined on virtual machine start. There are no fixed contextualization variables, but the datasource accepts many used and recommended across the documentation.

Datasource configuration

Datasource accepts following configuration options.

dsmode:
  values: local, net, disabled
  default: net

Tells if this datasource will be processed in ‘local’ (pre-networking) or ‘net’ (post-networking) stage or even completely ‘disabled’.

parseuser:
  default: nobody

Unprivileged system user used for contextualization script processing.

Contextualization disk

The following criteria are required:

Must be formatted with iso9660 filesystem or have a filesystem label of CONTEXT or CDROM
Must contain file context.sh with contextualization variables. File is generated by OpenNebula, it has a KEY=’VALUE’ format and can be easily read by bash

Contextualization variables

There are no fixed contextualization variables in OpenNebula, no standard. Following variables were found on various places and revisions of the OpenNebula documentation. Where multiple similar variables are specified, only first found is taken.

DSMODE

Datasource mode configuration override. Values: local, net, disabled.

DNS
ETH<x>_IP
ETH<x>_NETWORK
ETH<x>_MASK
ETH<x>_GATEWAY
ETH<x>_GATEWAY6
ETH<x>_DOMAIN
ETH<x>_DNS
ETH<x>_SEARCH_DOMAIN
ETH<x>_MTU
ETH<x>_IP6
ETH<x>_IP6_ULA
ETH<x>_IP6_PREFIX_LENGTH
ETH<x>_IP6_GATEWAY

Static network configuration.

SET_HOSTNAME
HOSTNAME

Instance hostname.

PUBLIC_IP
IP_PUBLIC
ETH0_IP

If no hostname has been specified, cloud-init will try to create hostname from instance’s IP address in ‘local’ dsmode. In ‘net’ dsmode, cloud-init tries to resolve one of its IP addresses to get hostname.

SSH_KEY
SSH_PUBLIC_KEY

One or multiple SSH keys (separated by newlines) can be specified.

USER_DATA
USERDATA

cloud-init user data.

Example configuration

This example cloud-init configuration (cloud.cfg) enables OpenNebula datasource only in ‘net’ mode.

disable_ec2_metadata: True
datasource_list: ['OpenNebula']
datasource:
  OpenNebula:
    dsmode: net
    parseuser: nobody

Example VM’s context section

CONTEXT=[
  SSH_KEY="$USER[SSH_KEY]
$USER[SSH_KEY1]
$USER[SSH_KEY2]",
  PUBLIC_IP="$NIC[IP]",
  USER_DATA="#cloud-config
# see https://help.ubuntu.com/community/CloudInit

packages: []

mounts:
- [vdc,none,swap,sw,0,0]
runcmd:
- echo 'Instance has been configured by cloud-init.' | wall
" ]