Debian headless/remote installation
I wanted to install Debian on a server remotely – i.e. without any keyboard access or the chance to peek at a temporarily connected screen. I found plenty of information on the net but none of the tutorials really worked for me. Some included preseeding the image but failed to automatically start the installation without a key press, others seemed to customize a zillion things but ended up getting stuck in some error message or other. The problem with ssh remote installation with stock images is that they still require some initial human interaction to select the desired menu option and some basic setup before the network is configured. That makes the whole point of remote installation moot...
So I read my way through lots of tutorials and put together a slim working solution – at least working for me. So here is my minimal and lazy solution to Debian headless installation image building. I mostly documented it for myself but maybe it's useful for someone out there.
In a nutshell
# Edit the configuration variables
make config
# Get a netinst image
make download
# Create and adapt preseed.cfg
cp minimal-preseed.cfg preseed.cfg
vim preseed.cfg
# Build image
make image
# OPTIONAL: test iso image in qemu
make qemu-bios
make qemu-uefi
# Write image to usb stick
make usb
# optional: Add a FAT32 partition on the remaining free space
make FAT
Dependencies
Make sure all necessary tools are installed:
make install-depends
Configure some things
Edit Makevars and set the variables to match your situation. You can use
make config
to do so. At the very minimum you need to set the following variables – e.g.:
RELEASE_NO = 11.2.0
ARCH = amd64
USBDEV = /dev/sdc
Please set RELEASE_NO for the Debian release you want to install. This is used to
download the example-preseed.cfg file that matches your release and to construct
the correct image filenames.
ARCH indicates the target processor architecture – amd64 or i386. This
variable is used to construct the correct Debian image name, identify the
installation folder in the image (install.amd) and download the correct
preseeding example file for your OS version. LABEL is the CD volume label and
USBDEV is the device that represents your usb stick. The latter is needed for
make usb and make FAT Be extra careful to set USBDEV correctly! If
you set it incorrectly, you may overwrite your system disk! QEMU is the name
of the qemu-system binary that matches the target architecture (optional).
I didn't have much luck with booting i386 images via UEFI – neither the stock images not the remastered ones. But maybe it's just my particular machine/BIOS...
A minimal-preseed.cfg file is included. That file configures the bare minimum
to get past the installer questions before the ssh connection becomes
available. To get a full example-preeed.cfg file directly from Debian, make example-preseed.cfg. Use any of these files as a template to create a custom
configuration file. This is also the place to configure the login password for
the network installation. For comprehensive information on preseeding, study
this:
https://www.debian.org/releases/stable/amd64/apb.en.html
You can override the automatic generation of source/target file names and image label by setting the respective variables in the config file. This may be handy if you want to use this for Debian derived distributions such as Ubuntu – those should work but are largely untested.
Download the Debian installation image
Download the latest Debian netinst installation image (currently only amd64):
make download
If you want to start off an image other than the latest DEBIAN netinst, you
have to download it yourself and set the SOURCE variable in the config file
(make config). Ubuntu etc. should work, too.
Build the ISO
make clean
make image
Dry run it
This step is optional but may save you a lot of trouble later.
make qemu-bios
make qemu-uefi
This will fire up a QEMU session booting your new image.
You can follow the boot process in the emulator and eventually connect to the installer like this:
ssh installer@localhost -p22222
So you can test-drive the installation before walking over to the server room.
The default password is r00tme – please change it in the preseeding file.
Write to usb stick or burn cd
If you still have a cdrom drive, use your favorite ISO burner to write the image to cd. I can't find my old usb-cd drive and prefer using a usb stick, anyway:
Insert a USB stick and find out its device file
lsblk
Double check, that USBDEV is set correctly in Makevars.
Caution: The next two steps will write to the device configured in the
USBDEV. If you failed to set that correctly, you will overwrite whatever disk
happens to be associated with that device!
Write the image to the stick:
make usb
Add a FAT partition to the stick:
make FAT
This may be useful if you need to add custom firmware files or anything else you would like to use during installation.
Remote Installation via ssh
Insert the USB stick (or CD) in the target system and power it up. Wait for a moment for the installer to boot and bring up the network. Find out the IP address of the machine (e.g. from the router/DHCP server). Alternatively, configure static IP in the preseed file. Once the system is up you should be able to ping it. Now log in and complete the installation remotely:
ssh installer@yourmachine
The default password is r00tme; it can (and should!) be configured in the
preseeding file. Alternatively, set a host key in preseeding for passwordless
login.
NOTE: The included minimal-preseed.cfg assumes that you are connected via
ethernet (as a server should be). If you want to/must use a wifi connection you
need to configure this.
And just because it took me a while to realize: The Debian remote-installer
uses screen to provide multiple virtual consoles. You can switch between them
with CTRL-a TAB. See man screen for more information.