SmartOS Datasource

This datasource finds metadata and user-data from the SmartOS virtualization platform (i.e. Joyent).

Please see http://smartos.org/ for information about SmartOS.

SmartOS Platform

The SmartOS virtualization platform uses meta-data to the instance via the second serial console. On Linux, this is /dev/ttyS1. The data is a provided via a simple protocol: something queries for the data, the console responds responds with the status and if “SUCCESS” returns until a single “.n”.

New versions of the SmartOS tooling will include support for base64 encoded data.

Meta-data channels

Cloud-init supports three modes of delivering user/meta-data via the flexible channels of SmartOS.

  • user-data is written to /var/db/user-data
    • per the spec, user-data is for consumption by the end-user, not provisioning tools
    • cloud-init entirely ignores this channel other than writing it to disk
    • removal of the meta-data key means that /var/db/user-data gets removed
    • a backup of previous meta-data is maintained as /var/db/user-data.<timestamp>. <timestamp> is the epoch time when cloud-init ran
  • user-script is written to /var/lib/cloud/scripts/per-boot/99_user_data
    • this is executed each boot
    • a link is created to /var/db/user-script
    • previous versions of the user-script is written to /var/lib/cloud/scripts/per-boot.backup/99_user_script.<timestamp>. - <timestamp> is the epoch time when cloud-init ran.
    • when the ‘user-script’ meta-data key goes missing, the user-script is removed from the file system, although a backup is maintained.
    • if the script does not start with a shebang (i.e. starts with #!<executable>), then or is not an executable, cloud-init will add a shebang of “#!/bin/bash”
  • cloud-init:user-data is treated like on other Clouds.
    • this channel is used for delivering _all_ cloud-init instructions
    • scripts delivered over this channel must be well formed (i.e. must have a shebang)

Cloud-init supports reading the traditional meta-data fields supported by the SmartOS tools. These are:

  • root_authorized_keys
  • hostname
  • enable_motd_sys_info
  • iptables_disable
Note: At this time iptables_disable and enable_motd_sys_info are read but
are not actioned.

Disabling user-script

Cloud-init uses the per-boot script functionality to handle the execution of the user-script. If you want to prevent this use a cloud-config of:

#cloud-config
cloud_final_modules:
 - scripts-per-once
 - scripts-per-instance
 - scripts-user
 - ssh-authkey-fingerprints
 - keys-to-console
 - phone-home
 - final-message
 - power-state-change

Alternatively you can use the json patch method

#cloud-config-jsonp
[
     { "op": "replace",
       "path": "/cloud_final_modules",
       "value": ["scripts-per-once",
                 "scripts-per-instance",
                 "scripts-user",
                 "ssh-authkey-fingerprints",
                 "keys-to-console",
                 "phone-home",
                 "final-message",
                 "power-state-change"]
     }
]

The default cloud-config includes “script-per-boot”. Cloud-init will still ingest and write the user-data but will not execute it, when you disable the per-boot script handling.

Note: Unless you have an explicit use-case, it is recommended that you not
disable the per-boot script execution, especially if you are using any of the life-cycle management features of SmartOS.

The cloud-config needs to be delivered over the cloud-init:user-data channel in order for cloud-init to ingest it.

base64

The following are exempt from base64 encoding, owing to the fact that they are provided by SmartOS:

  • root_authorized_keys
  • enable_motd_sys_info
  • iptables_disable
  • user-data
  • user-script

This list can be changed through system config of variable ‘no_base64_decode’.

This means that user-script and user-data as well as other values can be base64 encoded. Since Cloud-init can only guess as to whether or not something is truly base64 encoded, the following meta-data keys are hints as to whether or not to base64 decode something:

  • base64_all: Except for excluded keys, attempt to base64 decode the values. If the value fails to decode properly, it will be returned in its text
  • base64_keys: A comma delimited list of which keys are base64 encoded.
  • b64-<key>: for any key, if there exists an entry in the metadata for ‘b64-<key>’ Then ‘b64-<key>’ is expected to be a plaintext boolean indicating whether or not its value is encoded.
  • no_base64_decode: This is a configuration setting (i.e. /etc/cloud/cloud.cfg.d) that sets which values should not be base64 decoded.

disk_aliases and ephemeral disk

By default, SmartOS only supports a single ephemeral disk. That disk is completely empty (un-partitioned with no filesystem).

The SmartOS datasource has built-in cloud-config which instructs the ‘disk_setup’ module to partition and format the ephemeral disk.

You can control the disk_setup then in 2 ways:

  1. through the datasource config, you can change the ‘alias’ of ephermeral0 to reference another device. The default is:

    ‘disk_aliases’: {‘ephemeral0’: ‘/dev/vdb’},

    Which means anywhere disk_setup sees a device named ‘ephemeral0’ then /dev/vdb will be substituted.

  2. you can provide disk_setup or fs_setup data in user-data to overwrite the datasource’s built-in values.

See doc/examples/cloud-config-disk-setup.txt for information on disk_setup.