16.14. Automating Debian Installations with Preseed Files

Problem

You want a fairly simple way to automate network installation of new Debian PCs, and to create custom installations for different roles, such as web servers, workstations, file servers, and so forth.

Solution

Create a preseed, or preconfiguration file, that answers the installer questions, and does your package selections for you. First, study the example preseed file at http://d-i.alioth.debian.org/manual/example-preseed.txt Then, create one from your own Debian system by running these two commands:

	# debconf-get-selections --installer > preseed.txt
	# debconf-get-selections >> file preseed.txt

Your own preseed.txt is going to look different from the example-preseed.txt; it's messier and has a lot more entries. You can't use your own preseed.txt as-is, but you can see exactly what was done on your system, and you can copy anything you want to duplicate to example-preseed.txt.

The tasksel command selects package groups. You can see a list of these:

	$ tasksel --list-tasks 
	u desktop  Desktop environment
	i web-server  Web server
	u print-server  Print server
	u dns-server  DNS server
	[...]

u means uninstalled, and i means installed. Display individual packages with this command:

	$ tasksel --task-packages desktop
	twm
	gimp-print
	xresprobe
	openoffice.org
	[...]

Use tasksel to select package groups in your preseed file like this:

	#tasksel tasksel/desktop multiselect kde-desktop, xfce-desktop 
	#tasksel tasksel/first multiselect standard, kde-desktop

This means when the desktop task is selected, install kde-desktop and xfce-desktop instead of the default selections. Individual packages are selected with pkgsel, like this:

	d-i pkgsel/include string openvpn tftpd-hpa dnsmasq

I like to automate creating the root login, and disable the creation of a normal user account (because I do it later manually):

	passwd passwd/root-password password $1$AiJg3$GHlS8/vqkSgBj9/1EKPUv0
	passwd passwd/root-password-again password $1$AiJg3$GHlS8/vqkSgBj9/1EKPUv0
	passwd passwd/make-user boolean false

Keeping cleartext passwords around is a bad idea, so you can encrypt them first with:

	$ grub-md5-crypt
	Password:
	Retype password:
	$1$AiJg3$GHlS8/vqkSgBj9/1EKPUv0

This command checks the format of your preseed file to make sure it is valid:

	$ debconf-set-selections -c preseed.txt

After you have fine-tuned your preseed file and debconf-set-selections approves, how do you use it? With PXE netboot clients, copy your preseed file to /var/lib/tftpboot. Then, edit the auto boot stanza in /var/lib/tftpboot/pxelinux.cfg/default to point to the file:

	LABEL auto
	    kernel debian-installer/i386/linux
	    append auto=true priority=critical vga=normal \
	preseed/url=http://host/path/to/preseed.cfg \
	initrd=debian-installer/i386/initrd.gz --

You can copy your preseed file to the top-level directory on your USB flash drive and then enter this boot command:

	linux preseed/file=/dev/sdb/preseed.cfg debconf/priority=critical

Or, you can park your preseed file on a network server and then, for both CD and USB boot media, enter the URL:

	linux preseed/url=http://servername/filename

Discussion

Debian's preseed files are not as easy as Fedora's Kickstart. But, it is one of the easier methods for creating customized Debian autoinstalls. See the Debian-Gnu Installation Guide (http://d-i.alioth.debian.org/manual/en.i386/index.html) for a detailed discussion of preseed and boot options.

See Also