AutomatedServerInstalls

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== Introduction == Please direct feedback on this proposal to [[https://community.ubuntu.com/t/please-review-design-for-automated-server-installs/11923|community.ubuntu.com]] or [[https://lists.ubuntu.com/mailman/listinfo/ubuntu-server|the ubuntu-server mailing list]].
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The server installer for 20.04 supports a new mode of operation: automated (or unattended, or hands-off) installation, autoinstallation for short. <<TableOfContents()>>
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This lets you answer all those configuration questions ahead of time in an ''autoinstall file'' and lets the installation process run without any interaction. = Introduction =
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== Differences from preseeding == 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 =
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 * 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: if there is any autoinstall config at all, the installer takes the default for any unanswered question  * 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: if there is any autoinstall config at all, the installer takes the default for any unanswered question (and fails if there is no default).
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== Providing the autoinstall file == = Providing the autoinstall file =
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 * As /autoinstall.cfg in the initrd
 * As /autoinstall.cfg on the install media (in any partition!)		  * As `/autoinstall.cfg` in the initrd
 * As `/autoinstall.cfg` on the install media
 * As `/autoinstall.cfg` on a filesystem with label "autoinstall"
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And maybe these ways if people think they would be useful:

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

== Creating an autoinstall file ==		 = Creating an autoinstall file =
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== The format of an autoinstall file == = The format of an autoinstall file =
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The autoinstall file is YAML. Here is an example file that shows off most features: The autoinstall file is YAML and has [[/ConfigReference|full documentation]].
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{{{#!yaml A minimal config (for a single disk system) is:

{{{
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early_commands:
    - ping -c1 198.162.1.1
locale: en_US
keyboard:
    layout: en
    variant: uk
network:
    version: 2
    network:
        eth0:
            dhcp4: yes
proxy: http://squid.internal:3128/
mirror: http://repo.internal/
filesystem:
    recipe:
        name: lvm
identity:
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ssh:
    authorized_keys:
      - $key
    allow_pw: no
snaps:
    - go/stable
debconf_selections: |
    bind9 bind9/run-resolvconf boolean false
packages:
    - libreoffice
    - dns-server^
late_commands:
    - rm -rf /etc/init.d
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Many keys and values correspond straightforwardly to questions the installer asks (e.g. keyboard selection). There are some new options though: Here is an example file that shows off most features:
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 * `early_commands`: shell commands run after the installer has started, but before anything else (in particular, before scanning the system for block devices)
 * `debconf_selections` & `packages`: packages and configuration for them to be installed after installation has completed
 * `late_commands`: shell commands to run after the install has completed and any updates and packages installed, just before the system reboots		 [[/ConfigReference#version|version]]`: 1`<<BR>>
[[/ConfigReference#early_commands|early_commands]]`:`<<BR>>
` - ping -c1 198.162.1.1`<<BR>>
[[/ConfigReference#locale|locale]]`: en_US`<<BR>>
[[/ConfigReference#keyboard|keyboard]]`:`<<BR>>
` layout: en`<<BR>>
` variant: uk`<<BR>>
[[/ConfigReference#network|network]]`:`<<BR>>
` version: 2`<<BR>>
` network:`<<BR>>
` eth0:`<<BR>>
` dhcp4: yes`<<BR>>
[[/ConfigReference#proxy|proxy]]`: http://squid.internal:3128/`<<BR>>
[[/ConfigReference#mirror|mirror]]`: http://repo.internal/`<<BR>>
[[/ConfigReference#filesystem|filesystem]]`:`<<BR>>
` layout:`<<BR>>
` name: lvm`<<BR>>
[[/ConfigReference#identity|identity]]`:`<<BR>>
` username: mwhudson`<<BR>>
` password: $crypted_pass`<<BR>>
[[/ConfigReference#ssh|ssh]]`:`<<BR>>
` install_server: yes`<<BR>>
` authorized_keys:`<<BR>>
` - $key`<<BR>>
` allow_pw: no`<<BR>>
[[/ConfigReference#snaps|snaps]]`:`<<BR>>
` - go/stable`<<BR>>
[[/ConfigReference#debconf_selections|debconf_selections]]`: |`<<BR>>
` bind9 bind9/run-resolvconf boolean false`<<BR>>
[[/ConfigReference#packages|packages]]`:`<<BR>>
` - libreoffice`<<BR>>
` - dns-server^`<<BR>>
[[/ConfigReference#late_commands|late_commands]]`:`<<BR>>
` - touch /target/autoinstalled`
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=== Filesystem configuration === 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.
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Filesystem configuration is a complex topic and the description of the desired configuration in the autoinstall file can necessarily also be complex. The installer does support "recipes", simple ways of expressing common configurations. = Possible future directions =
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==== Supported recipes ==== There are other places we could put the autoinstall config:
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lvm & simple  * As a b64encoded gzipped blob on the kernel command line
 * Given as a URL via DHCP
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==== action-based config ==== Possibly the installer should support reporting progress to some endpoint.
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For full flexibility, the installer allows filesystem configuration to be done using a syntax which is a superset of that supported by curtin, described at https://curtin.readthedocs.io/en/latest/topics/storage.html. We could add syntax to indicate that the user should still be asked for the answer to some question or other.

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).

This document is entirely a description of something that does not yet exist

Automated Server Installs for 20.04 (and maybe 18.04.4?)

This document is entirely a description of something that does not yet exist

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

Contents

  1. Automated Server Installs for 20.04 (and maybe 18.04.4?)
  2. Introduction
  3. Differences from debian-installer preseeding
  4. Providing the autoinstall file
  5. Creating an autoinstall file
  6. The format of an autoinstall file
  7. Possible future directions

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: if there is any autoinstall config at all, the installer takes the default for any unanswered question (and fails if there is no default).

Providing the autoinstall file

The autoinstall file can be provided in the following ways:

  • As /autoinstall.cfg in the initrd

  • As /autoinstall.cfg on the install media

  • As /autoinstall.cfg 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.cfg.

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
# edit existing autoinstall file
$ autoinstall-editor autoinstall.cfg

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
    username: mwhudson
    password: $crypted_pass

Here is an example file that shows off most features:

version: 1
early_commands:
    - ping -c1 198.162.1.1
locale: en_US
keyboard:
    layout: en
    variant: uk
network:
    version: 2
    network:
        eth0:
            dhcp4: yes
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^
late_commands:
    - touch /target/autoinstalled

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

Possibly the installer should support reporting progress to some endpoint.

We could add syntax to indicate that the user should still be asked for the answer to some question or other.

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).

FoundationsTeam/AutomatedServerInstalls (last edited 2020-06-11 04:19:11 by mwhudson)