Autoinstall configuration reference manual

The autoinstall file uses the YAML format. At the top level is a single key, autoinstall, which contains a mapping of the keys described in this document. Unrecognised keys are ignored in version 1, but they will cause a fatal validation error in future versions.

Here is an example of a minimal autoinstall configuration:

autoinstall:
  version: 1
  identity:
   ...

At the top level is the autoinstall keyword. It contains a version section and an (incomplete) identity section, which are explained in more detail below. Any other key at the level of autoinstall results in an autoinstall validation error at run time.

Note

This behaviour was first introduced during 24.04 (Noble). On any ISOs built before 24.04, you need to refresh the installer to see this behaviour.

Technically, in all but one case the top level autoinstall keyword is strictly unnecessary. This keyword is only necessary when serving autoinstall via cloud-config. For backwards compatibility, this format is still supported for delivery methods not based on cloud-config; however, it is highly recommended to use the format with a top-level autoinstall keyword because mistakes in this formatting are a common source of confusion.

Schema

Autoinstall configurations are validated against a JSON schema before they are used.

Command lists

Several configuration keys are lists of commands to be executed. Each command can be a string (in which case it is executed via sh -c) or a list, in which case it is executed directly. Any command exiting with a non-zero return code is considered an error and aborts the installation (except for error-commands, where it is ignored).

Top-level keys

The following keys can be used to configure various aspects of the installation. If the global autoinstall key is provided, then all “top-level keys” must be provided underneath it and “top-level” refers to this sub-level. The examples below demonstrate this structure.

Warning

In version 1, Subiquity emits warnings when encountering unrecognised keys. In later versions, it results in a fatal validation error, and the installation halts.

version

  • type: integer

  • default: no default

A future-proofing configuration file version field. Currently, this must be 1.

interactive-sections

  • type: list of strings

  • default: []

A list of configuration keys to still show in the user interface (UI). For example:

autoinstall:
  version: 1
  interactive-sections:
    - network
  identity:
    username: ubuntu
    password: $crypted_pass

This example stops on the network screen and allows the user to change the defaults. If a value is provided for an interactive section, it is used as the default.

You can use the special section name of * to indicate that the installer should ask all the usual questions – in this case, the autoinstall.yaml file is an autoinstall file. It just provides a way to change the defaults in the UI.

Not all configuration keys correspond to screens in the UI. This documentation indicates if a given section can be interactive or not.

If there are any interactive sections at all, the reporting key is ignored.

early-commands

  • type: command list

  • default: no commands

  • can be interactive: no

A list of shell commands to invoke as soon as the installer starts, in particular before probing for block and network devices. The autoinstall configuration is available at /autoinstall.yaml (irrespective of how it was provided), and the file is re-read after the early-commands have run to allow them to alter the configuration if necessary.

locale

  • type: string

  • default: en_US.UTF-8

  • can be interactive: true

The locale to configure for the installed system.

refresh-installer

  • type: mapping

  • default: see below

  • can be interactive: true

Controls whether the installer updates to a new version available in the given channel before continuing.

The mapping contains keys:

update

  • type: boolean

  • default: false

Whether to update or not.

channel

  • type: string

  • default: "stable/ubuntu-$REL"

The channel to check for updates.

keyboard

  • type: mapping, see below

  • default: US English keyboard

  • can be interactive: true

The layout of any attached keyboard. The mapping keys correspond to settings in the /etc/default/keyboard configuration file. See the keyboard(5) manual page for more details.

The mapping contains keys:

layout

  • type: string

  • default: "us"

Corresponds to the XKBLAYOUT setting.

variant

  • type: string

  • default: ""

Corresponds to the XKBVARIANT setting.

toggle

  • type: string or null

  • default: null

Corresponds to the value of grp: option from the XKBOPTIONS setting. Acceptable values are (the installer does not validate these):

  • caps_toggle

  • toggle

  • rctrl_toggle

  • rshift_toggle

  • rwin_toggle

  • menu_toggle

  • alt_shift_toggle

  • ctrl_shift_toggle

  • ctrl_alt_toggle

  • alt_caps_toggle

  • lctrl_lshift_toggle

  • lalt_toggle

  • lctrl_toggle

  • lshift_toggle

  • lwin_toggle

  • sclk_toggle

Warning

The version of Subiquity released with 20.04 GA does not accept null for this field due to a bug.

source

  • type: mapping, see below

  • default: see below

  • can be interactive: true

search_drivers

  • type: boolean

  • default: true (mostly, see below)

Whether the installer searches for available third-party drivers. When set to false, it disables the drivers screen and section.

The default is true for most installations, and false when a “core boot” or “enhanced secure boot” method is selected (where third-party drivers cannot be currently installed).

id

  • type: string

  • default: identifier of the first available source.

Identifier of the source to install (e.g., ubuntu-server-minimal).

network

  • type: Netplan-format mapping, see below

  • default: DHCP on interfaces named eth* or en*

  • can be interactive: true

Netplan-formatted network configuration. This is applied during installation as well as in the installed system. The default is to interpret the configuration for the installation media, which runs DHCP version 4 on any interface with a name matching eth* or en* but then disables any interface that does not receive an address.

For example, to run DHCP version 6 on a specific network interface:

autoinstall:
  network:
    version: 2
    ethernets:
      enp0s31f6:
        dhcp6: true

Note that in the 20.04 GA release of Subiquity, the behaviour is slightly different and requires you to write this with an extra network: key:

autoinstall:
  network:
    network:
      version: 2
      ethernets:
        enp0s31f6:
          dhcp6: true

Versions later than 20.04 support this syntax, too (for compatibility). When using a newer version, use the regular syntax.

proxy

  • type: URL or null

  • default: no proxy

  • can be interactive: true

The proxy to configure both during installation and for apt and snapd in the target system.

apt

  • type: mapping

  • default: see below

  • can be interactive: true

APT configuration, used both during the installation and once booted into the target system.

This section historically used the same format as curtin, which is documented in the APT Source section of the curtin documentation. Nonetheless, some key differences with the format supported by curtin have been introduced:

  • Subiquity supports an alternative format for the primary section, allowing configuration of a list of candidate primary mirrors. During installation, Subiquity automatically tests the specified mirrors and selects the first one that appears usable. This new behaviour is only activated when the primary section is wrapped in the mirror-selection section.

  • The fallback key controls what Subiquity does when no primary mirror is usable.

  • The geoip key controls whether to perform IP-based geolocation to determine the correct country mirror.

The default is:

autoinstall:
  apt:
    preserve_sources_list: false
    mirror-selection:
      primary:
        - country-mirror
        - arches: [i386, amd64]
          uri: "http://archive.ubuntu.com/ubuntu"
        - arches: [s390x, arm64, armhf, powerpc, ppc64el, riscv64]
          uri: "http://ports.ubuntu.com/ubuntu-ports"
    fallback: abort
    geoip: true

mirror-selection

If the primary section is contained within the mirror-selection section, the automatic mirror selection is enabled. This is the default in new installations.

primary (when placed inside the mirror-selection section)

  • type: custom, see below

In the new format, the primary section expects a list of mirrors, which can be expressed in two different ways:

  • The special country-mirror value

  • A mapping with the following keys:

    • uri: The URI of the mirror to use, e.g., http://fr.archive.ubuntu.com/ubuntu.

    • arches: An optional list of architectures supported by the mirror. By default, this list contains the current CPU architecture.

fallback

  • type: string (enumeration)

  • default: offline-install

Controls what Subiquity does when no primary mirror is usable. Supported values are:

  • abort: abort the installation

  • offline-install: revert to an offline installation

  • continue-anyway: attempt to install the system anyway (not recommended; the installation fails)

geoip

  • type: boolean

  • default: true

If geoip is set to true and one of the candidate primary mirrors has the special value country-mirror, a request is made to https://geoip.ubuntu.com/lookup. Subiquity then sets the mirror URI to http://CC.archive.ubuntu.com/ubuntu (or similar for ports) where CC is the country code returned by the lookup. If this section is not interactive, the request expires after 10 seconds.

If the legacy behaviour (i.e., without mirror-selection) is in use, the geolocation request is made if the mirror to be used is the default, and its URI is replaced by the proper country mirror URI.

To specify a mirror, use a configuration like this:

autoinstall:
  apt:
    mirror-selection:
      primary:
        - uri: YOUR_MIRROR_GOES_HERE
        - country-mirror
        - uri: http://archive.ubuntu.com/ubuntu

To add a PPA:

autoinstall:
  apt:
    sources:
      curtin-ppa:
        source: ppa:curtin-dev/test-archive

storage

  • type: mapping, see below

  • default: use the lvm layout on single-disk systems; there is no default for multiple-disk systems

  • can be interactive: true

Storage configuration is a complex topic, and the description of the desired configuration in the autoinstall file can also be complex. The installer supports “layouts”; simple ways of expressing common configurations.

Supported layouts

The three supported layouts at the time of writing are lvm, direct and zfs.

autoinstall:
  storage:
    layout:
      name: lvm
  storage:
    layout:
      name: direct
  storage:
    layout:
      name: zfs

By default, these layouts install to the largest disk in a system, but you can supply a match spec (see below) to indicate which disk to use:

autoinstall:
  storage:
    layout:
      name: lvm
      match:
        serial: CT*
  storage:
    layout:
      name: direct
      match:
        ssd: true

Note

Match spec – using match: {} matches an arbitrary disk.

When using the lvm layout, LUKS encryption can be enabled by supplying a password.

autoinstall:
  storage:
    layout:
      name: lvm
      password: LUKS_PASSPHRASE

The default is to use the lvm layout.

Sizing-policy

The lvm layout, by default, attempts to leave room for snapshots and further expansion. A sizing-policy key may be supplied to control this behaviour.

  • type: string (enumeration)

  • default: scaled

Supported values are:

  • scaled: Adjust space allocated to the root logical volume (LV) based on space available to the volume group (VG).

  • all: Allocate all remaining VG space to the root LV.

The scaling system uses the following rules:

  • Less than 10 GiB: use all remaining space for the root file system

  • Between 10–20 GiB: 10 GiB root file system

  • Between 20–200 GiB: use half of the remaining space for the root file system

  • Greater than 200 GiB: 100 GiB root file system

Example with no size scaling and a passphrase:

autoinstall:
  storage:
    layout:
      name: lvm
      sizing-policy: all
      password: LUKS_PASSPHRASE

Reset Partition

reset-partition is used for creating a Reset Partition, which is a FAT32 file system containing the entire content of the installer image, so that the user can start the installer from GRUB or EFI without using the installation media. This option is useful for OEM system provisioning.

By default, the size of a Reset Partition is roughly 1.1x the used file system size of the installation media.

An example to enable Reset Partition:

autoinstall:
  storage:
    layout:
      name: direct
      reset-partition: true

The size of the reset partition can also be fixed to a specified size. This is an example to fix Reset Partition to 12 GiB:

autoinstall:
  storage:
    layout:
      name: direct
      reset-partition: 12G

The installer can also install Reset Partition without installing the system. To do this, set reset-partition-only to true:

autoinstall:
  storage:
    layout:
      name: direct
      reset-partition: true
      reset-partition-only: true

Action-based configuration

For full flexibility, the installer allows storage configuration to be done using a syntax that is a superset of that supported by curtin, as described in the Storage section of the curtin documentation.

If the layout feature is used to configure the disks, the config section is not used.

The list of actions can be added under the config key, and the grub and swap curtin configuration items can also be included here.

An example storage section:

autoinstall:
  storage:
    swap:
      size: 0
    config:
      - type: disk
        id: disk0
        serial: ADATA_SX8200PNP_XXXXXXXXXXX
      - type: partition
        ...

The extensions to the curtin syntax allow for disk selection and partition or logical-volume sizing.

Disk selection extensions

Curtin supported identifying disks by serial numbers (e.g. Crucial_CT512MX100SSD1_14250C57FECE) or by path (e.g. /dev/sdc), and the server installer supports this, too. The installer additionally supports a “match spec” on a disk action, which provides for more flexible matching.

The actions in the storage configuration are processed in the order they are in the autoinstall file. Any disk action is assigned a matching disk – chosen arbitrarily from the set of unassigned disks if there is more than one, and causing the installation to fail if there is no unassigned matching disk.

A match spec supports the following keys:

  • model: value: matches a disk where ID_MODEL=value in udev, supporting globbing

  • vendor: value: matches a disk where ID_VENDOR=value in udev, supporting globbing

  • path: value: matches a disk based on path (e.g. /dev/sdc), supporting globbing (the globbing support distinguishes this from specifying path: value directly in the disk action)

  • id_path: value: matches a disk where ID_PATH=value in udev, supporting globbing

  • devpath: value: matches a disk where DEVPATH=value in udev, supporting globbing

  • serial: value: matches a disk where ID_SERIAL=value in udev, supporting globbing (the globbing support distinguishes this from specifying serial: value directly in the disk action)

  • ssd: true|false: matches a disk that is or is not an SSD (as opposed to a rotating drive)

  • size: largest|smallest: take the largest or smallest disk rather than an arbitrary one if there are multiple matches (support for smallest added in version 20.06.1)

A special sort of key is install-media: true, which takes the disk the installer was loaded from (the ssd and size selectors never return this disk). If installing to the installation media, be careful to not overwrite the installer itself.

For example, to match an arbitrary disk:

- type: disk
  id: disk0

To match the largest SSD:

- type: disk
  id: big-fast-disk
  match:
    ssd: true
    size: largest

To match a Seagate drive:

- type: disk
  id: data-disk
  match:
    model: Seagate

As of Subiquity 24.08.1, match specs may optionally be specified in an ordered list, and will use the first match spec that matches one or more unused disks:

# attempt first to match by serial, then by path
- type: disk
  id: data-disk
  match:
    - serial: Foodisk_1TB_ABC123_1
    - path: /dev/nvme0n1

Partition/logical volume extensions

The size of a partition or logical volume in curtin is specified as a number of bytes. The autoinstall configuration is more flexible:

  • You can specify the size using the 1G, 512M syntax supported in the installer UI.

  • You can specify the size as a percentage of the containing disk (or RAID), e.g. 50%.

  • For the last partition specified for a particular device, you can specify the size as -1 to indicate that the partition should fill the remaining space.

- type: partition
  id: boot-partition
  device: root-disk
  size: 10%
- type: partition
  id: root-partition
  size: 20G
- type: partition
  id: data-partition
  device: root-disk
  size: -1

identity

  • type: mapping, see below

  • default: no default

  • can be interactive: true

Configure the initial user for the system. This is the only configuration key that must be present (unless the user-data section is present, in which case it is optional).

A mapping that can contain keys, all of which take string values:

realname

The real name for the user. This field is optional.

username

The user name to create.

hostname

The hostname for the system.

password

The password for the new user, encrypted. This is required for use with sudo, even if SSH access is configured.

The encrypted password string must conform to what the passwd command requires. See the passwd(1) manual page for details. Quote the password hash to ensure correct treatment of any special characters.

Several tools can generate the encrypted password, such as mkpasswd from the whois package, or openssl passwd.

Example:

autoinstall:
  identity:
    realname: 'Ubuntu User'
    username: ubuntu
    password: '$6$wdAcoXrU039hKYPd$508Qvbe7ObUnxoj15DRCkzC3qO7edjH0VV7BPNRDYK4QR8ofJaEEF2heacn0QgD.f8pO8SNp83XNdWG6tocBM1'
    hostname: ubuntu

active-directory

  • type: mapping, see below

  • default: no default

  • can be interactive: true

Accepts data required to join the target system in an Active Directory domain.

A mapping that can contain keys, all of which take string values:

admin-name

A domain account name with the privilege to perform the join operation. The account password is requested during run time.

domain-name

The Active Directory domain to join.

ubuntu-pro

  • type: mapping, see below

  • default: see below

  • can be interactive: true

token

  • type: string

  • default: no token

A contract token to attach to an existing Ubuntu Pro subscription.

ssh

  • type: mapping, see below

  • default: see below

  • can be interactive: true

Configure SSH for the installed system. A mapping that can contain the following keys:

install-server

  • type: boolean

  • default: false

Whether to install the OpenSSH server in the target system.

authorized-keys

  • type: list of strings

  • default: []

A list of SSH public keys to install in the initial user account.

allow-pw

  • type: boolean

  • default: true if authorized_keys is empty, false otherwise

codecs

  • type: mapping, see below

  • default: see below

  • can be interactive: no

Configure whether common restricted packages (including codecs) from the multiverse repository are to be installed.

install

  • type: boolean

  • default: false

Whether to install the ubuntu-restricted-addons package.

drivers

  • type: mapping, see below

  • default: see below

  • can be interactive: true

install

  • type: boolean

  • default: false

Whether to install the available third-party drivers.

oem

  • type: mapping, see below

  • default: see below

  • can be interactive: no

install

  • type: boolean or string (special value auto)

  • default:: auto

Whether to install the available OEM meta-packages. The special value auto – which is the default – enables the installation on Ubuntu Desktop but not on Ubuntu Server. This option has no effect on core boot classic.

snaps

  • type: list

  • default: install no extra snaps

  • can be interactive: true

A list of snaps to install. Each snap is represented as a mapping with a required name and an optional channel (default is stable) and classic (default is false) keys. For example:

autoinstall:
  snaps:
    - name: etcd
      channel: edge
      classic: false

debconf-selections

  • type: string

  • default: no configuration

  • can be interactive: no

The installer updates the target with debconf set-selection values. Users need to be familiar with the options of the debconf package.

packages

  • type: list

  • default: no packages

  • can be interactive: no

A list of packages to install into the target system. Specifically, a list of strings to pass to the apt-get install command. Therefore, this includes things such as task selection (dns-server^) and installing particular versions of a package (my-package=1-1).

kernel

  • type: mapping (mutually exclusive), see below

  • default: default kernel

  • can be interactive: no

Which kernel gets installed. Either the name of the package or the name of the flavour must be specified.

package

type: string

The name of the package, e.g., linux-image-5.13.0-40-generic.

flavor

  • type: string

The flavor of the kernel, e.g., generic or hwe.

timezone

  • type: string

  • default: no timezone

  • can be interactive: no

The timezone to configure on the system. The special value geoip can be used to query the timezone automatically over the network.

updates

  • type: string (enumeration)

  • default: security

  • can be interactive: no

The type of updates that will be downloaded and installed after the system installation. Supported values are:

  • security: download and install updates from the -security pocket.

  • all: also download and install updates from the -updates pocket.

shutdown

  • type: string (enumeration)

  • default: reboot

  • can be interactive: no

Request the system to power off or reboot automatically after the installation has finished. Supported values are:

  • reboot

  • poweroff

late-commands

  • type: command list

  • default: no commands

  • can be interactive: no

Shell commands to run after the installation has completed successfully and any updates and packages installed, just before the system reboots. The commands are run in the installer environment with the installed system mounted at /target. You can run curtin in-target -- $shell_command (with the version of Subiquity released with 20.04 GA, you need to specify this as curtin in-target --target=/target -- $shell_command) to run in the target system (similar to how plain in-target can be used in d-i preseed/late_command).

error-commands

  • type: command list

  • default: no commands

  • can be interactive: no

Shell commands to run after the installation has failed. They are run in the installer environment, and the target system (or as much of it as the installer managed to configure) is mounted at /target. Logs will be available in /var/log/installer in the live session.

reporting

  • type: mapping

  • default: type: print (which causes output on tty1 and any configured serial consoles)

  • can be interactive: no

The installer supports reporting progress to a variety of destinations. Note that this section is ignored if there are any interactive sections; it only applies to fully automated installations.

The configuration is similar to that used by curtin. See the Reporting section of the curtin documentation.

Each key in the reporting mapping in the configuration defines a destination where the type sub-key is one of:

  • print: print progress information on tty1 and any configured serial console. There is no other configuration.

  • rsyslog: report progress via rsyslog. The destination key specifies where to send output. (The rsyslog reporter does not yet exist.)

  • webhook: report progress by sending JSON reports to a URL using POST requests. Accepts the same configuration as curtin.

  • none: do not report progress. Only useful to inhibit the default output.

Reporting examples:

The default configuration is:

autoinstall:
  reporting:
    builtin:
      type: print

Report to rsyslog:

autoinstall:
  reporting:
    central:
      type: rsyslog
      destination: "@192.168.0.1"

Suppress the default output:

autoinstall:
  reporting:
    builtin:
      type: none

Report to a curtin-style webhook:

autoinstall:
  reporting:
    hook:
      type: webhook
      endpoint: http://example.com/endpoint/path
      consumer_key: "ck_value"
      consumer_secret: "cs_value"
      token_key: "tk_value"
      token_secret: "tk_secret"
      level: INFO

user-data

  • type: mapping

  • default: {}

  • can be interactive: no

Provide cloud-init user data, which will be merged with the user data the installer produces. If you supply this, you don’t need to supply an identity section (in that case, ensure you can log in to the installed system).