SmartOS Datasource#

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

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

SmartOS platform#

The SmartOS virtualisation platform uses metadata from the instance via the second serial console. On Linux, this is /dev/ttyS1. The data is provided via a simple protocol:

  • Something queries for the data,

  • the console 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.

Metadata channels#

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

  1. User data is written to /var/db/user-data:

    • As per the spec, user data is for consumption by the end user, not provisioning tools.

    • Cloud-init 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 metadata is maintained as /var/db/user-data.<timestamp>. <timestamp> is the epoch time when cloud-init ran.

  2. 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 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 metadata key goes missing, user-script is removed from the file system, although a backup is maintained.

    • If the script does not start with a shebang (i.e., it starts with #!<executable>), or it is not an executable, cloud-init will add a shebang of “#!/bin/bash”.

  3. 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., they must have a shebang).

Cloud-init supports reading the traditional metadata 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.

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

Note

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

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 the datasource base configuration variable no_base64_decode.

This means that user-script, user-data and other values can be Base64 encoded. Since cloud-init can only guess whether or not something is truly Base64 encoded, the following metadata 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 an entry exists in the metadata for 'b64-<key>', then 'b64-<key>' is expected to be a plain-text 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 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'}

    This means that 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.