Starting with Ubuntu 20.10 (Groovy Gorilla), Canonical does not provide the netboot.tar.gz package and the mini.iso image anymore. They could previously be used to boot a system via PXE and run Debian Installer automated via a preseed configuration.
How can Ubuntu versions starting with 20.10 be installed automatically via PXE boot?
Introduction
Instead of having a small package specific to the task, it's now necessary to use the regular full ISO image. Only the server installer Subiquity can be automated, so it's required to use the server image even for a desktop installation.
The following steps are for the current version 21.04 (Hirsute Hippo). For future versions, replace all occurrences of
21.04by the version number you want to install.Prerequisites
Prerequisites on the server machine that is going to serve the PXE files, installer image and autoinstall configuration:
pxelinux,syslinux-efi,syslinux-commoninstalledServing the ISO image and autoinstall config
wget https://releases.ubuntu.com/21.04/ubuntu-21.04-live-server-amd64.isometa-dataanduser-datain the directory.user-databy using https://ubuntu.com/server/docs/install/autoinstall-reference as a referencePreparing and serving the PXE environment
Go to the directory your TFTP server serves, by default
/srv/tftpCopy the ISO image downloaded in the previous section to the current directory
Create some directories that we are going to use in the following steps:
mkdir -p iso_mount init boot/uefi boot/bios pxelinux.cfgMount the image and extract the kernel and initrd:
Prepare the PXELINUX files for booting via UEFI as well as via BIOS:
Configure your DHCP server to set the boot filename to
boot/uefi/syslinux.efifor UEFI clients andboot/bios/pxelinux.0for BIOS clientsCreate a PXELINUX config at
pxelinux.cfg/defaultsimilar to the following. Replace the URLs in angle brackets by the URLs to your web server: Replace<iso url>by the URL to the ISO image and<autoinstall url>by the URL to the directory containing the autoinstall configuration (including a trailing slash!).Link the PXELINUX config into the
bootdirectories for UEFI and BIOS:Conclusion
You should now be able to boot both UEFI and BIOS clients via PXE into the Subiquity installer, which will then run automated according to your autoinstall config.
Desktop installation
If you are installing a desktop system, it's necessary to install the
ubuntu-desktoppackage.You'll also need to fix the network configuration in the installed system, since Subiquity enables
systemd-networkdinstead ofNetworkManager, which is normally used on desktop systems:Remove the network configuration created by Subiquity:
rm /etc/netplan/00-installer-config.yamlCreate a file
/etc/netplan/01-network-manager-all.yamlwith the following contents:Run
netplan applyor rebootWell, I could just as well put in my take on this... so here it goes!
Intro
Below is a full PXE guide, from setting up server and all required services, up to first boots. It also includes instructions for both Ubuntu 20.04.1 and 20.10, with automatic install of Ubuntu Server, interactive install of Server, and Live boot of Desktop (like PXE version of "Live CD"). Guide had been modified slightly to include all options in one boot menu with all variations. Both BIOS and UEFI scenarios are explained.
I am using component of Syslinux called "lpxelinux" (first lowercase "L"), which has support to boot kernel and init from HTTP as well.
syslinux.efialready has this as well. HTTP enables faster transfers, plus enables us to have a little bit different organization of files, plus some other minor advantages down the line (for larger implementations).This is full step-by-step guide!
PXE Server - Ubuntu 20.04.1 LTS
Install Ubuntu Server as usual, start with minimum installed options, but I usually enable OpenSSH server to enable remote administration. After install make sure to update it fully
Tools and requirements
We need TFTP server, HTTP(S) server, and DHCP server. You can use other servers if you already have them, but for ease of following we will install everything on our newly installed Ubuntu 20.04.1 LTS
I picked most popular packages:
We will also need to fetch syslinux files. Since Marian's guide already showed how to get those from apt packages, I'll go other way, for completeness sake (you can mix and match approaches as you wish). We get files from official
kernel.orgI used the chance to create a temp dir for us under
/root/pxeandsyslinuxdirectory underneath it. Feel free to place these files wherever you wish, just make sure to amend commands afterwards.SYSLINUX - LPXELINUX (files)
Next we copy files that we'll need. Feel free to copy more modules, but these are enough.
TFTPD already has a directory which we will use, under:
/var/lib/tftpboot/Copy the files there, in separate directories (some files have same names but are intended for different architectures)
DHCP server
DHCP server itself should have a static IP. So let's do that (if you haven't done it during install).
Edit the network config (YAML file):
Contents:
Apply the config:
Next we need to enter basic config for DHCP server's zones and pools. I'm doing some extra config here to show you that your future PXE clients can be in subnets different from your PXE server. In my case PXE server (with all services) is at
10.10.2.1. I have two subnets connected via virtual router :10.10.1.0/24and10.10.2.0/24Contents (just an example):
Note: Please modify the file according to your situation! You have to have correct subnets, gateways, as well as correct MAC address (hardware address) of your clients!
And you will need to set interface where DHCP deamon will listen, use
ip ato check which interface that would be for you (I have it ateth0)Contents:
Make sure to restart the service:
And enable it to autostart on server reboots:
If you have typos or other mistakes like duplicate IPs or client names, deamon will fail. Check logs if status is red.
OPTIONAL - router settings
If you have different subnets, make sure you add
ip helperfor DHCP, also often setup asDHCP relayin most routers. Just point it to IP address of your PXE server (if you have services spread on multiple servers, then point it to one that holds DHCP services).TFTP server
We need to setup basic stuff for TFTP server, but only one option really needs changing/checking - path to your root TFTP directory
/var/lib/tftpbootContents:
Make sure to restart the service as well.
And enable it to autostart on server reboots:
You can use TFTP client to test the service if you want to be sure all is well.
SYSLINUX / (l)pxelinux configs
We need some configs to boot! At minimum we need one
defaultfile for each architecture. We place them in TFTP directoryContents of the file:
Note I am pulling both
vmlinuzandinitrdfrom HTTP server. Same server is hosting ISO image and our autoinstall files. We will setup this web server next, no worries.Since
defaultlooks same for both BIOS and UEFI, just copy it (or link it if you wish).If you keep them separate you can change the options on them individually. Menu also accepts linking through
includeoption. But if you want advanced menus, read docs or few more articles.Web server - HTTP(S)
I will describe simple HTTP setup, but you can expand that to HTTPS later. It would be recommended if your environment isn't closed, and you have passwords set in autoinstall files. For basic lab, we use HTTP.
We need to fetch the ISOs. Since I've put in both server and desktop in the menu, I will repeat this once for each ISO. I know question is about the server, but extras won't hurt you. If you want just server or desktop simply skip the other.
This is for Ubuntu Server LTS 20.04.1
Extract the kernel and initramfs (vmlinuz and initrd) to subfolder of that distro/variation/version. You can have many more on your multi-boot PXE menu.
This is for Desktop LTS 20.04.1
And again extract, note I added different name of folder
The following is for Ubuntu Server 20.10
Extract the files, again to separate folder
And finally this is for Ubuntu Desktop 20.10
Extract the files again, to separate folder once more
That should be it. Test with your browser to see if you can reach the files in correct locations. We used default Apache directory on Ubuntu to host all files, so no extra steps should be needed.
Autoinstall file for Server 20.04 and 20.10
Ubuntu docs say you can simply install one server, then find a sample file with your selections in
/var/log/installer/autoinstall-user-datafile.To test in a lab, you can use that file as your template, but it will require some modifications.
To just have a minimal config you can use code below (again YAML code, beware spacing if doing manual edits):
Contents:
Note: This config will setup server with hostname
pxe-client, and username and password both beingpxe. Server will have no network (DHCP disabled), so it will skip auto-update during install (for quicker testing). And it will have OpenSSH server preinstalled, with password login. Note regional stuff (hr= Croatia, so we have Croatian mirror setup for apt, and Croatian keyboard layout), tweak them for your country. See your sample/var/log/installer/autoinstall-user-dataas a template to add your own tweaks.Ubuntu requires
meta-datafile as well. It HAS TO be empty. So just create it in same directory where you've putuser-datafileTo see more options see official docs: https://ubuntu.com/server/docs/install/autoinstall-reference
For Ubuntu 20.10 everything is the same, just copy the code, or create it in correct path:
Use same user-data sample, they are interchangeable between 20.04 and 20.10. Also note the double
network: network:part.. 20.04 had a bug where it requred such setup, while 20.10 doesn't have the bug, but supports this as a backward compatibility feature.Check your files
I would recommend you to check that you have all files in place for all variations:
Server folders should have 4 files:
Desktop folders should have 2 files:
If you have trouble booting, check the permissions of files listed above. If you are doing lab, just do unsafe thing and
chmodit all with full rw permissions:For production setup proper permissions with just read access where needed.
Testing it all
In my lab environment, as well as when starting new production setup, I test this all in VMs first. I use Hyper-V for testing (I know, kill me, with Microsoft stuff here suddenly :) ). To test UEFI boot you create
Generation 2machine, and for BIOS boot you should useGeneration 1machine. Make sure to add enough RAM to VM to hold the RAMDISK ! So if VM is testing Server with 1,5GB RAM disk, then you need 2GB RAM for VM, and for Desktop we have 3GB RAM disk so best to have 4GB RAM attached to VM. Also, make sure to attach network interfaces to correct networks, as I mentioned before, I keep a virtual router and multiple subnets, as I need to test and proof this all for deployment in quite large and complicated environments.Anyway, once you have VM - just boot it! If you did everything correctly you should see PXE boot, VM getting IP, then starting the menu. After 30 sec it will boot from disk, but just use arrow keys to select an option. I found UEFI booting way faster in my tests, so I usually tested with UEFI, then tested BIOS VM once UEFI was where I wanted it.
Wrapping it up
Only now will I admit I'm no Linux guru. But I spent a lot of time past month and a half doing PXE boots and setting up different environments for it and with it. This is pure Ubuntu stack in this tutorial. I plan to write one a bit more Microsoft oriented, but also based on SYSLINUX with multi-boot menu, and allowing us to boot (assorted) Linux distros (in addition to Windows). All of this can be made with any DHCP/HTTP/TFTP tools, including Microsoft Windows Server 2019, with couple roles installed on it (DHCP, IIS, WDS). Likewise, you can use any other distro to act as PXE server for your Ubuntu installs. You don't need to use Apache2 either, if you are more comfortable with eg. nginx as your HTTP server.
For the end, I did all my tests with both Ubuntu 20.04 and 20.10. The whole setup is EXACTLY THE SAME for both versions. Just change names of files and ISO downloads. If you just need one of them, just skip the parts for what you don't need.
Happy hunting!
Edit: 2020-11-14 - added everything for Ubuntu 20.10, cleaned some code, and added more meaningful names for folders since we are handling 4 different OS boots now.