Example Preseed file tutorial for Debian Lenny PXEboot Server

 The Default File

The next step for our PXE Server (for the previous step see here) is to make an option for an automated deployment.  This is especially useful in a production environment as you can network boot a computer, feed the appropriate options in the command line and walk away, with entire confidence that the OS will install flawlessly.  Now for the preseed file to work correctly the default file needs to be edited (again, see here). 
DISPLAY boot.txt DEFAULT lenny_i386_install LABEL lenny_i386_autoinstall kernel debian/lenny/i386/linux append ramdisk_size=14984 locale=en_US console-setup/layoutcode=en_US netcfg/wireless_wep= netcfg/choose_interface=eth0 netcfg/get_hostname=DebianServer netcfg/get_domain= console-keymaps-at/keymap=us url=http://192.168.1.100/pxescripts/preseed.cfg initrd=debian/lenny/i386/initrd.gz -- LABEL lenny_i386_install kernel debian/lenny/i386/linux append vga=normal initrd=debian/lenny/i386/initrd.gz -- LABEL lenny_i386_linux kernel debian/lenny/i386/linux append vga=normal initrd=debian/lenny/i386/initrd.gz -- LABEL lenny_i386_expert kernel debian/lenny/i386/linux append priority=low vga=normal initrd=debian/lenny/i386/initrd.gz -- LABEL lenny_i386_rescue kernel debian/lenny/i386/linux append vga=normal initrd=debian/lenny/i386/initrd.gz rescue/enable=true -- LABEL xen_i386_install kernel xen/vmlinuz append vga=normal initrd=xen/initrd.gz -- PROMPT 1 TIMEOUT 40
If you inspect the file above you will notice the line that is used for the preseed.cfg file, which must be one line, but is broken in this example for formatting. :

LABEL lenny_i386_autoinstall kernel debian/lenny/i386/linux append ramdisk_size=14984 locale=en_US console-setup/layoutcode=en_US netcfg/wireless_wep= netcfg/choose_interface=eth0 netcfg/get_hostname=DebianServer netcfg/get_domain= console-keymaps-at/keymap=us url=http://IP ADDRESS/pxescripts/preseed.cfg initrd=debian/lenny/i386/initrd.gz --

Alright, lets break a little bit of this down.  In order for our auto installation scheme to work, there need to be some options passed on directly to the kernel, and lets go over a few of them.
1. ramdisk_size - stores some execution space in the RAM, speeds things up.
2. locale=en_US and console-setup/layoutcode=en_US - setting US English as the default language
3. netcfg/wireless_wep - I believe this is for a wireless password, but not entirely sure.
4. netcfg/choose_interface - This allows you to chose the network interface that will be used
5. netcfg/get_hostname - allows you to set the hostname of the machine.
6. netcfg/get_domain - allows you to set the domain of the computer
7. console-keymaps-at/keymap - allows you to set the keyboard mapping
8. url=http://IP ADDRESS/PATH/preseed.cfg - specifies where the preseed.cfg file can be found.
Now you will notice that many of these are defined in the default file... if I wasn't lazy, and this was a work environment, it would be better to manually enter at least one of these, namely netcfg/get_hostname.  This way I would not have to go back and change the hostname for almost all of the machines... a big time saver.  As well, you'll notice that to fetch the preseed.cfg file I used a http:// address.. I believe a ftp:// and file:// prefix will work as well.  Now, the reason these options all need to be passed on directly to the kernel is because many of these options are asked before the networking is configured.  So until the machines gets an IP address during installation (which is after the language is decided) the preseed.cfg file is not available to fill in the answers... so these options need to be directly passed onto the kernel.

The Preseed.cfg File

d-i debian-installer/locale string en_US d-i console-setup/layoutcode string en_US d-i netcfg/choose_interface select auto # Keyboard selection. #d-i console-tools/archs select at d-i console-keymaps-at/keymap select us # Any hostname and domain names assigned from dhcp take precedence over # values set here. However, setting the values still prevents the questions # from being shown, even if values come from dhcp. d-i netcfg/get_hostname string DebianTest d-i netcfg/get_domain string domain_not_set.invalid d-i netcfg/wireless_wep string ### Mirror settings # If you select ftp, the mirror/country string does not need to be set. d-i mirror/country string us d-i mirror/http/countries select us #d-i mirror/protocol string ftp d-i mirror/http/hostname string ftp.us.debian.org d-i mirror/http/directory string /debian d-i mirror/http/proxy string http://192.168.1.100:3142 # Suite to install. #d-i mirror/suite string testing # Suite to use for loading installer components (optional). #d-i mirror/udeb/suite string testing d-i mirror/suite string lenny ### Partitioning # If the system has free space you can choose to only partition that space. # Note: this must be preseeded with a localized (translated) value. #d-i partman-auto/init_automatically_partition \ # select Guided - use the largest continuous free space # Alternatively, you can specify a disk to partition. The device name must # be given in traditional non-devfs format. # Note: A disk must be specified, unless the system has only one disk. # For example, to use the first SCSI/SATA hard disk: d-i partman-auto/disk string /dev/hda # In addition, you'll need to specify the method to use. # The presently available methods are: "regular", "lvm" and "crypto" d-i partman-auto/method string lvm # If one of the disks that are going to be automatically partitioned # contains an old LVM configuration, the user will normally receive a # warning. This can be preseeded away... d-i partman-lvm/device_remove_lvm boolean true # The same applies to pre-existing software RAID array: d-i partman-md/device_remove_md boolean true # And the same goes for the confirmation to write the lvm partitions. d-i partman-lvm/confirm boolean true # You can choose one of the three predefined partitioning recipes: # - atomic: all files in one partition # - home: separate /home partition # - multi: separate /home, /usr, /var, and /tmp partitions d-i partman-auto/choose_recipe select atomic # This makes partman automatically partition without confirmation. d-i partman/confirm_write_new_label boolean true d-i partman/choose_partition \ select Finish partitioning and write changes to disk d-i partman/confirm boolean true ### Clock and time zone setup # Controls whether or not the hardware clock is set to UTC. d-i clock-setup/ust boolean true # You may set this to any valid setting for $TZ; see the contents of # /usr/share/zoneinfo/ for valid values. d-i time/zone string EST ### Apt setup # You can choose to install non-free and contrib software. #d-i apt-setup/non-free boolean true #d-i apt-setup/contrib boolean true # Uncomment this if you don't want to use a network mirror. #d-i apt-setup/use_mirror boolean false # Select which update services to use; define the mirrors to be used. # Values shown below are the normal defaults. #d-i apt-setup/services-select multiselect security, volatile #d-i apt-setup/security_host string security.debian.org #d-i apt-setup/volatile_host string volatile.debian.org # Additional repositories, local[0-9] available #d-i apt-setup/local0/repository string \ # http://local.server/debian stable main #d-i apt-setup/local0/comment string local server # Enable deb-src lines #d-i apt-setup/local0/source boolean true # URL to the public key of the local repository; you must provide a key or # apt will complain about the unauthenticated repository and so the # sources.list line will be left commented out #d-i apt-setup/local0/key string http://local.server/key ### Account setup # Skip creation of a root account (normal user account will be able to # use sudo). #d-i passwd/root-login boolean false # Alternatively, to skip creation of a normal user account. #d-i passwd/make-user boolean false # Root password, either in clear text d-i passwd/root-password password ********** d-i passwd/root-password-again password ********** # or encrypted using an MD5 hash. #d-i passwd/root-password-crypted password [MD5 hash] # To create a normal user account. d-i passwd/user-fullname string Debian Server Administrator d-i passwd/username string deranjer # Normal user's password, either in clear text #d-i passwd/user-password password insecure #d-i passwd/user-password-again password insecure # or encrypted using an MD5 hash. d-i passwd/user-password-crypted password $1$ApZFpRq5$X38skX90ZL36YOnbYt/3J #Set environment # This is fairly safe to set, it makes grub install automatically to the MBR # if no other operating system is detected on the machine. d-i grub-installer/only_debian boolean true # This one makes grub-installer install to the MBR if it also finds some other # OS, which is less safe as it might not be able to boot that other OS. d-i grub-installer/with_other_os boolean true # Individual additional packages to install d-i pkgsel/include string openssh-server webmin nxclient ### Package selection tasksel tasksel/first multiselect standard, desktop #tasksel tasksel/first multiselect standard, web-server #tasksel tasksel/first multiselect standard, kde-desktop ### Opt out of the popularity contest d-i popularity-contest/participate boolean false ### Finishing up the first stage install # Avoid that last message about the install being complete. d-i finish-install/reboot_in_progress note xserver-xorg xserver-xorg/autodetect_monitor boolean true xserver-xorg xserver-xorg/config/monitor/selection-method \ select medium xserver-xorg xserver-xorg/config/monitor/mode-list \ select 1024x768 @ 60 Hz
Now I will explain some of the more cryptic/hard to grasp elements of the preseed.cfg file
The first few lines set the installer language and keyboard layout... I don't think those are necessary, they should have passed directly to the kernel.  Next, I am telling the installer to automatically choose the interface to use.  The next few lines are not necessary, as we passed those on directly to the kernel.  The mirror settings section is very important, especially if (like me) you decided to cache (using apt-cache or apt-mirror) files to ease bandwidth traffic.  The first two lines select the country, and the directory string sets the distribution.  The proxy string is the key for making sure the files are pulled from your personal apt-cache.  As you can see, I'm pulling it from my web server, with the port for my apt-cache defined. Next, the suite specifies the version of the linux distro.  The partitioning can be difficult to set up, especially if your machines have one, two or more hard drives.  If the machine only has one hard drive, specifying a hard drive is not necessary.  Since one of my testing machines has two hard drives, I added the "d-i partman-auto/disk string /dev/hda", which specifies that the installer should use the first hard disk.  Next, after selecting lvm for the method, you can choose one of the pre-defined partitioning schemes.  The options are:
# - atomic: all files in one partition
# - home:   separate /home partition
# - multi:  separate /home, /usr, /var, and /tmp partitions
As you can see, I chose the atomic method.  For improved performance, you may want to choose one of the other methods.
Next, you can set up the user accounts and passwords.  The first thing you can do is set the root password.  In the example, the password is sent in clear test (it is masked in the example), but I certainly recommend you send the password as a MD5 hash.  To generate a MD5 hash, just run the following command:

$echo "password" | mkpasswd -s -H MD5

Next, you can choose the package that you want to install.  I chose the standard desktop install.
Essentially, that covers the trickier parts of the preseed.cfg file.  Happy automated installing!