Администраторам Falcot Corp, как и многим администраторам больших IT-инфраструктур, необходимы инструменты для быстрой установки (или переустановки), причём по возможности автоматической, на новых машинах.

Эти потребности можно удовлетворить с помощью широкого диапазона решений. С одной стороны, универсальные инструменты вроде SystemImager делают это, создавая образ, основанный на шаблонной машине, после чего развёртывают этот образ на целевых системах; с другой стороны, стандартный установщик Debian может быть преднастроен с помощью конфигурационного файла, содержащего ответы на задаваемые в процессе установки вопросы. Промежуточным вариантом являются такие гибридные инструменты как FAI (Fully Automatic Installer), которые производят установку с помощью пакетной системы, но также используют свою собственную инфраструктуру для задач, специфичных для массового развёртывания (таких как запуск, разметка, конфигурирование и т. п.).

Each of these solutions has its pros and cons: SystemImager works independently from any particular packaging system, which allows it to manage large sets of machines using several distinct Linux distributions. It also includes an update system that doesn't require a reinstallation, but this update system can only be reliable if the machines are not modified independently; in other words, the user must not update any software on their own, or install any other software. Similarly, security updates must not be automated, because they have to go through the centralized reference image maintained by SystemImager. This solution also requires the target machines to be homogeneous, otherwise many different images would have to be kept and managed (an amd64 image won't fit on a powerpc machine, and so on).

On the other hand, an automated installation using debian-installer can adapt to the specifics of each machine: the installer will fetch the appropriate kernel and software packages from the relevant repositories, detect available hardware, partition the whole hard disk to take advantage of all the available space, install the corresponding Debian system, and set up an appropriate bootloader. However, the standard installer will only install standard Debian versions, with the base system and a set of pre-selected “tasks”; this precludes installing a particular system with non-packaged applications. Fulfilling this particular need requires customizing the installer… Fortunately, the installer is very modular, and there are tools to automate most of the work required for this customization, most importantly simple-cdd (CDD being an acronym for Custom Debian Derivative). Even this solution, however, only handles initial installations; this is usually not a problem since the APT tools allow efficient deployment of updates later on.

We will only give a rough overview of FAI, and skip SystemImager altogether (which is no longer in Debian, but available as a third-party package), in order to focus more intently on debian-installer and simple-cdd, which are more interesting in a Debian-only context.

d-i netcfg/hostname string worker
d-i netcfg/hostname seen false

menuentry --hotkey=i 'Install' {
    set background_color=black
    linux    /install.amd/vmlinuz preseed/file=/cdrom/preseed.cfg locale=en_US.UTF-8 keymap=us language=us country=US vga=788 --- quiet 
    initrd   /install.amd/initrd.gz
}

label install
        menu label ^Install
        kernel [...]
        append preseed/file=/cdrom/preseed.cfg locale=en_US.UTF-8 keymap=us language=us country=US vga=788 initrd=/install.amd/initrd.gz --- quiet

default vmlinuz
append preseed/file=/hd-media/preseed.cfg locale=en_US.UTF-8 keymap=us language=us country=US vga=788 initrd=initrd.gz  --