Automated Server Installs for 20.04 (and maybe 18.04.4?)

Please direct feedback on this proposal to community.ubuntu.com or the ubuntu-server mailing list.

Introduction

The server installer for 20.04 supports a new mode of operation: automated installation, autoinstallation for short. You might also know this feature as unattended or handsoff or preseeded installation.

Autoinstallation lets you answer all those configuration questions ahead of time in an autoinstall file and lets the installation process run without any interaction.

Differences from debian-installer preseeding

preseeds are the way to automate an installer based on debian-installer (aka d-i).

autoinstalls for the new server installer differ from preseeds in the following main ways:

• the file format is completely different (yaml vs debconf-set-selections format)
• when the answer to a question is not present in a preseed, d-i stops and asks the user for input. autoinstalls are not like this: by default, if there is any autoinstall config at all, the installer takes the default for any unanswered question (and fails if there is no default). You can designate particular sections in the config as "interactive", which means the installer will still stop and ask about those.

Providing the autoinstall file

The autoinstall file can be provided in the following ways:

• As /autoinstall.yaml in the initrd

• As /autoinstall.yaml on the install media

• As /autoinstall.yaml on a filesystem with label "autoinstall"

• Via a http or https (or maybe tftp) URL on the kernel command line

Creating an autoinstall file

When any system is installed using the server installer, an autoinstall file for repeating the install is created at /var/log/installer/autoinstall.yaml.

Alternatively there is a snap, autoinstall-editor, that can be used to either edit or create from scratch an autoinstall file (it is actually mostly the same code as that that runs the installation in interactive mode).

# start editing new config file
$ autoinstall-editor
# dump out to stdout a complete autoinstall config file with default answers everywhere
$ autoinstall-editor --create > my-autoinstall.yaml
# edit existing autoinstall file
$ autoinstall-editor my-autoinstall.yaml

The format of an autoinstall file

The autoinstall file is YAML and has full documentation.

A minimal config (for a single disk system) is:

version: 1
identity:
    username: mwhudson
    password: $crypted_pass

Here is an example file that shows off most features:

version: 1
reporting:
    hook:
        type: webhook
        endpoint: http://example.com/endpoint/path
early_commands:
    - ping -c1 198.162.1.1
locale: en_US
keyboard:
    layout: en
    variant: uk
network:
    version: 2
    network:
        ethernets:
            enp0s25:
               dhcp4: yes
            enp3s0:
            enp4s0:
        bonds:
            bond0:
                dhcp4: yes
                interfaces:
                    - enp3s0
                    - enp4s0
                parameters:
            mode: active-backup
            primary: enp3s0
proxy: http://squid.internal:3128/
mirror: http://repo.internal/
filesystem:
    layout:
        name: lvm
identity:
    username: mwhudson
    password: $crypted_pass
ssh:
    install_server: yes
    authorized_keys:
      - $key
    allow_pw: no
snaps:
    - go/stable
debconf_selections: |
    bind9      bind9/run-resolvconf    boolean false
packages:
    - libreoffice
    - dns-server^
cloud-init:
    disable_root: false
error_commands:
    - tar c /var/log/installer | nc 192.168.0.1 1000

Many keys and values correspond straightforwardly to questions the installer asks (e.g. keyboard selection). See the reference for details of those that do not.

Possible future directions

There are other places we could put the autoinstall config:

• As a b64encoded gzipped blob on the kernel command line
• Given as a URL via DHCP

We might want to extend the 'match specs' for disks to cover other ways of selecting disks.

We might want to add some way of customizing the apt sources (adding a PPA, etc). Possibly just by accepting more of the curtin syntax for this.

There are other things we could do by default in a system with multiple disks (create an LVM VG incorporating all of them, just install on one disk picked at random, install on the largest disk, etc etc).

We could support kickstart compatibility as in kickseed.