A script to generate a fully-automated ISO image for installing Ubuntu onto a machine without human interaction. This uses the new autoinstall method for Ubuntu 20.04 and newer.
Check out the usage information below for arguments. The basic idea is to take an unmodified Ubuntu ISO image, extract it, add some kernel command line parameters, then repack the data into a new ISO. This is needed for full automation because the autoinstall parameter must be present on the kernel command line, otherwise the installer will wait for a human to confirm. This script automates the process of creating an ISO with this built-in.
Autoinstall configuration (disk layout, language etc) can be passed along with cloud-init data to the installer. Some minimal information is needed for
the installer to work - see the Ubuntu documentation for an example, which is also in the user-data.example file in this repository (password: ubuntu). This data can be passed over the network (not yet supported in this script), via an attached volume, or be baked into the ISO itself.
To attach via a volume (such as a separate ISO image), see the Ubuntu autoinstall quick start guide. It's really very easy! To bake everything into a single ISO instead, you can use the -a flag with this script and provide a user-data file containing the autoinstall configuration and optionally cloud-init data, plus a meta-data file if you choose. The meta-data file is optional and will be empty if it is not specified. With an 'all-in-one' ISO, you simply boot a machine using the ISO and the installer will do the rest. At the end the machine will reboot into the new OS.
This script can use an existing ISO image or download the latest daily image from the Ubuntu project. Using a fresh ISO speeds things up because there won't be as many packages to update during the installation.
By default, the source ISO image is checked for integrity and authenticity using GPG. This can be disabled with -k.
Tested on a host running Ubuntu 20.04.1.
- Utilities required:
xorrisosedcurlgpgisolinux
Usage: ubuntu-autoinstall-generator.sh [-h] [-v] [-a] [-e] [-u user-data-file] [-m meta-data-file] [-k] [-c] [-r] [-s source-iso-file] [-d destination-iso-file]
💁 This script will create fully-automated Ubuntu 20.04 Focal Fossa installation media.
Available options:
-h, --help Print this help and exit
-v, --verbose Print script debug info
-a, --all-in-one Bake user-data and meta-data into the generated ISO. By default you will
need to boot systems with a CIDATA volume attached containing your
autoinstall user-data and meta-data files.
For more information see: https://ubuntu.com/server/docs/install/autoinstall-quickstart
-e, --use-hwe-kernel Force the generated ISO to boot using the hardware enablement (HWE) kernel. Not supported
by early Ubuntu 20.04 release ISOs.
-u, --user-data Path to user-data file. Required if using -a
-m, --meta-data Path to meta-data file. Will be an empty file if not specified and using -a
-k, --no-verify Disable GPG verification of the source ISO file. By default SHA256SUMS-<current date> and
SHA256SUMS-<current date>.gpg files in the script directory will be used to verify the authenticity and integrity
of the source ISO file. If they are not present the latest daily SHA256SUMS will be
downloaded and saved in the script directory. The Ubuntu signing key will be downloaded and
saved in a new keyring in the script directory.
-r, --use-release-iso Use the current release ISO instead of the daily ISO. The file will be used if it already
exists.
-s, --source Source ISO file. By default the latest daily ISO for Ubuntu 20.04 will be downloaded
and saved as <script directory>/ubuntu-original-<current date>.iso
That file will be used by default if it already exists.
-d, --destination Destination ISO file. By default <script directory>/ubuntu-autoinstall-<current date>.iso will be
created, overwriting any existing file.
user@testbox:~$ bash ubuntu-autoinstall-generator.sh -a -u user-data.example -d ubuntu-autoinstall-example.iso
[2020-12-23 14:06:07] 👶 Starting up...
[2020-12-23 14:06:07] 📁 Created temporary working directory /tmp/tmp.jrmlEaDhL3
[2020-12-23 14:06:07] 🔎 Checking for required utilities...
[2020-12-23 14:06:07] 👍 All required utilities are installed.
[2020-12-23 14:06:07] 🌎 Downloading current daily ISO image for Ubuntu 20.04 Focal Fossa...
[2020-12-23 14:08:01] 👍 Downloaded and saved to /home/user/ubuntu-original-2020-12-23.iso
[2020-12-23 14:08:01] 🌎 Downloading SHA256SUMS & SHA256SUMS.gpg files...
[2020-12-23 14:08:02] 🌎 Downloading and saving Ubuntu signing key...
[2020-12-23 14:08:02] 👍 Downloaded and saved to /home/user/843938DF228D22F7B3742BC0D94AA3F0EFE21092.keyring
[2020-12-23 14:08:02] 🔐 Verifying /home/user/ubuntu-original-2020-12-23.iso integrity and authenticity...
[2020-12-23 14:08:09] 👍 Verification succeeded.
[2020-12-23 14:08:09] 🔧 Extracting ISO image...
[2020-12-23 14:08:11] 👍 Extracted to /tmp/tmp.jrmlEaDhL3
[2020-12-23 14:08:11] 🧩 Adding autoinstall parameter to kernel command line...
[2020-12-23 14:08:11] 👍 Added parameter to UEFI and BIOS kernel command lines.
[2020-12-23 14:08:11] 🧩 Adding user-data and meta-data files...
[2020-12-23 14:08:11] 👍 Added data and configured kernel command line.
[2020-12-23 14:08:11] 👷 Updating /tmp/tmp.jrmlEaDhL3/md5sum.txt with hashes of modified files...
[2020-12-23 14:08:11] 👍 Updated hashes.
[2020-12-23 14:08:11] 📦 Repackaging extracted files into an ISO image...
[2020-12-23 14:08:14] 👍 Repackaged into /home/user/ubuntu-autoinstall-example.iso
[2020-12-23 14:08:14] ✅ Completed.
[2020-12-23 14:08:14] 🚽 Deleted temporary working directory /tmp/tmp.jrmlEaDhL3
Now you can boot your target machine using ubuntu-autoinstall-example.iso and it will automatically install Ubuntu using the configuration from user-data.example.
This script is based on this minimal safe bash template, and steps found in this discussion thread (particularly this script). The somewhat outdated Ubuntu documentation here was also useful.
MIT license.