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11.1 Использование системы конфигурации

The operating system is configured by providing an operating-system declaration in a file that can then be passed to the guix system command (see Invoking guix system). A simple setup, with the default Linux-Libre kernel, initial RAM disk, and a couple of system services added to those provided by default looks like this:

;; -*- mode: scheme; -*-
;; This is an operating system configuration template
;; for a "bare bones" setup, with no X11 display server.

(use-modules (gnu))
(use-service-modules networking ssh)
;; If you want to use HTTPS, you most likely want to include
;; "certs" in the line below.  Also read the comment about
;; "nss-certs" later in this file.
(use-package-modules screen ssh)

(operating-system
  (host-name "komputilo")
  (timezone "Europe/Berlin")
  (locale "en_US.utf8")

  ;; Boot in "legacy" BIOS mode, assuming /dev/sdX is the
  ;; target hard disk, and "my-root" is the label of the target
  ;; root file system.
  (bootloader (bootloader-configuration
                (bootloader grub-bootloader)
                (targets '("/dev/sdX"))))
  ;; It's fitting to support the equally bare bones ‘-nographic’
  ;; QEMU option, which also nicely sidesteps forcing QWERTY.
  (kernel-arguments (list "console=ttyS0,115200"))
  (file-systems (cons (file-system
                        (device (file-system-label "my-root"))
                        (mount-point "/")
                        (type "ext4"))
                      %base-file-systems))

  ;; This is where user accounts are specified.  The "root"
  ;; account is implicit, and is initially created with the
  ;; empty password.
  (users (cons (user-account
                (name "alice")
                (comment "Bob's sister")
                (group "users")

                ;; Adding the account to the "wheel" group
                ;; makes it a sudoer.  Adding it to "audio"
                ;; and "video" allows the user to play sound
                ;; and access the webcam.
                (supplementary-groups '("wheel"
                                        "audio" "video")))
               %base-user-accounts))

  ;; Globally-installed packages.
  ;; Add "nss-certs" for Mozilla's approved CA certs.  You would
  ;; have to have included "certs" in use-package-modules above.
  (packages (cons screen %base-packages))

  ;; Add services to the baseline: a DHCP client and an SSH
  ;; server.  You may wish to add an NTP service here.
  (services (append (list (service dhcp-client-service-type)
                          (service openssh-service-type
                                   (openssh-configuration
                                    (openssh openssh-sans-x)
                                    (port-number 2222))))
                    %base-services)))

The configuration is declarative and hopefully mostly self-describing. It is actually code in the Scheme programming language; the whole (operating-system …) expression produces a record with a number of fields. Some of the fields defined above, such as host-name and bootloader, are mandatory. Others, such as packages and services, can be omitted, in which case they get a default value. See operating-system Reference, for details about all the available fields.

Below we discuss the effect of some of the most important fields, and how to instantiate the operating system using guix system.

Do not panic: Intimidated by the Scheme language or curious about it? The Cookbook has a short section to get started that explains the fundamentals, which you will find helpful when hacking your configuration. See A Scheme Crash Course in GNU Guix Cookbook.

Bootloader

Поле bootloader описывает метод, который будет использоваться для загрузки вашей системы. Компьютеры на базе процессоров Intel могут загружаться в "устаревшем" режиме BIOS, как в примере выше. Однако более современные машины используют для загрузки Unified Extensible Firmware Interface (UEFI). В этом случае поле bootloader должно содержать примерно следующее:

(bootloader-configuration
  (bootloader grub-efi-bootloader)
  (targets '("/boot/efi")))

See Настройка загрузчика, для получения дополнительной информации о доступных параметрах конфигурации.

Globally-Visible Packages

В поле packages перечислены пакеты, которые будут глобально видны в системе, для всех учетных записей пользователей - т.е. в переменной окружения PATH каждого пользователя - в дополнение к профилям для каждого пользователя (see Вызов guix package). Переменная %base-packages предоставляет все инструменты, которые можно ожидать для выполнения основных задач пользователя и администратора, включая GNU Core Utilities, GNU Networking Utilities, легкий текстовый редактор mg, find, grep и т.д. В примере выше к ним добавляется GNU Screen, взятый из модуля (gnu packages screen) (see Пакетные модули). Синтаксис (list package output) можно использовать для добавления конкретного вывода пакета:

(use-modules (gnu packages))
(use-modules (gnu packages dns))

(operating-system
  ;; ...
  (packages (cons (list isc-bind "utils")
                  %base-packages)))

Referring to packages by variable name, like isc-bind above, has the advantage of being unambiguous; it also allows typos and such to be diagnosed right away as “unbound variables”. The downside is that one needs to know which module defines which package, and to augment the use-package-modules line accordingly. To avoid that, one can use the specification->package procedure of the (gnu packages) module, which returns the best package for a given name or name and version:

(use-modules (gnu packages))

(operating-system
  ;; ...
  (packages (append (map specification->package
                         '("tcpdump" "htop" "gnupg@2.0"))
                    %base-packages)))

When a package has more than one output it can be a challenge to refer to a specific output instead of just to the standard out output. For these situations one can use the specification->package+output procedure from the (gnu packages) module. For example:

(use-modules (gnu packages))

(operating-system
  ;; ...
  (packages (append (map specification->package+output
                         '("nss-certs" "git" "git:send-email"))
                    %base-packages)))

System Services

The services field lists system services to be made available when the system starts (see Сервисы). The operating-system declaration above specifies that, in addition to the basic services, we want the OpenSSH secure shell daemon listening on port 2222 (see openssh-service-type). Under the hood, openssh-service-type arranges so that sshd is started with the right command-line options, possibly with supporting configuration files generated as needed (see Создание служб).

Occasionally, instead of using the base services as is, you will want to customize them. To do this, use modify-services (see modify-services) to modify the list.

For example, suppose you want to modify guix-daemon and Mingetty (the console log-in) in the %base-services list (see %base-services). To do that, you can write the following in your operating system declaration:

(define %my-services
  ;; My very own list of services.
  (modify-services %base-services
    (guix-service-type config =>
                       (guix-configuration
                        (inherit config)
                        ;; Fetch substitutes from example.org.
                        (substitute-urls
                          (list "https://example.org/guix"
                                "https://ci.guix.gnu.org"))))
    (mingetty-service-type config =>
                           (mingetty-configuration
                            (inherit config)
                            ;; Automatically log in as "guest".
                            (auto-login "guest")))))

(operating-system
  ;; …
  (services %my-services))

This changes the configuration—i.e., the service parameters—of the guix-service-type instance, and that of all the mingetty-service-type instances in the %base-services list (see see the cookbook for how to auto-login one user to a specific TTY in GNU Guix Cookbook)). Observe how this is accomplished: first, we arrange for the original configuration to be bound to the identifier config in the body, and then we write the body so that it evaluates to the desired configuration. In particular, notice how we use inherit to create a new configuration which has the same values as the old configuration, but with a few modifications.

The configuration for a typical “desktop” usage, with an encrypted root partition, a swap file on the root partition, the X11 display server, GNOME and Xfce (users can choose which of these desktop environments to use at the log-in screen by pressing F1), network management, power management, and more, would look like this:

;; -*- mode: scheme; -*-
;; This is an operating system configuration template
;; for a "desktop" setup with GNOME and Xfce where the
;; root partition is encrypted with LUKS, and a swap file.

(use-modules (gnu) (gnu system nss) (guix utils))
(use-service-modules desktop sddm xorg)
(use-package-modules certs gnome)

(operating-system
  (host-name "antelope")
  (timezone "Europe/Paris")
  (locale "en_US.utf8")

  ;; Choose US English keyboard layout.  The "altgr-intl"
  ;; variant provides dead keys for accented characters.
  (keyboard-layout (keyboard-layout "us" "altgr-intl"))

  ;; Use the UEFI variant of GRUB with the EFI System
  ;; Partition mounted on /boot/efi.
  (bootloader (bootloader-configuration
                (bootloader grub-efi-bootloader)
                (targets '("/boot/efi"))
                (keyboard-layout keyboard-layout)))

  ;; Specify a mapped device for the encrypted root partition.
  ;; The UUID is that returned by 'cryptsetup luksUUID'.
  (mapped-devices
   (list (mapped-device
          (source (uuid "12345678-1234-1234-1234-123456789abc"))
          (target "my-root")
          (type luks-device-mapping))))

  (file-systems (append
                 (list (file-system
                         (device (file-system-label "my-root"))
                         (mount-point "/")
                         (type "ext4")
                         (dependencies mapped-devices))
                       (file-system
                         (device (uuid "1234-ABCD" 'fat))
                         (mount-point "/boot/efi")
                         (type "vfat")))
                 %base-file-systems))

  ;; Specify a swap file for the system, which resides on the
  ;; root file system.
  (swap-devices (list (swap-space
                       (target "/swapfile"))))

  ;; Create user `bob' with `alice' as its initial password.
  (users (cons (user-account
                (name "bob")
                (comment "Alice's brother")
                (password (crypt "alice" "$6$abc"))
                (group "students")
                (supplementary-groups '("wheel" "netdev"
                                        "audio" "video")))
               %base-user-accounts))

  ;; Add the `students' group
  (groups (cons* (user-group
                  (name "students"))
                 %base-groups))

  ;; This is where we specify system-wide packages.
  (packages (append (list
                     ;; for HTTPS access
                     nss-certs
                     ;; for user mounts
                     gvfs)
                    %base-packages))

  ;; Add GNOME and Xfce---we can choose at the log-in screen
  ;; by clicking the gear.  Use the "desktop" services, which
  ;; include the X11 log-in service, networking with
  ;; NetworkManager, and more.
  (services (if (target-x86-64?)
                (append (list (service gnome-desktop-service-type)
                              (service xfce-desktop-service-type)
                              (set-xorg-configuration
                               (xorg-configuration
                                (keyboard-layout keyboard-layout))))
                        %desktop-services)

                ;; FIXME: Since GDM depends on Rust (gdm -> gnome-shell -> gjs
                ;; -> mozjs -> rust) and Rust is currently unavailable on
                ;; non-x86_64 platforms, we use SDDM and Mate here instead of
                ;; GNOME and GDM.
                (append (list (service mate-desktop-service-type)
                              (service xfce-desktop-service-type)
                              (set-xorg-configuration
                               (xorg-configuration
                                (keyboard-layout keyboard-layout))
                               sddm-service-type))
                        %desktop-services)))

  ;; Allow resolution of '.local' host names with mDNS.
  (name-service-switch %mdns-host-lookup-nss))

A graphical system with a choice of lightweight window managers instead of full-blown desktop environments would look like this:

;; -*- mode: scheme; -*-
;; This is an operating system configuration template
;; for a "desktop" setup without full-blown desktop
;; environments.

(use-modules (gnu) (gnu system nss))
(use-service-modules desktop)
(use-package-modules bootloaders certs emacs emacs-xyz ratpoison suckless wm
                     xorg)

(operating-system
  (host-name "antelope")
  (timezone "Europe/Paris")
  (locale "en_US.utf8")

  ;; Use the UEFI variant of GRUB with the EFI System
  ;; Partition mounted on /boot/efi.
  (bootloader (bootloader-configuration
                (bootloader grub-efi-bootloader)
                (targets '("/boot/efi"))))

  ;; Assume the target root file system is labelled "my-root",
  ;; and the EFI System Partition has UUID 1234-ABCD.
  (file-systems (append
                 (list (file-system
                         (device (file-system-label "my-root"))
                         (mount-point "/")
                         (type "ext4"))
                       (file-system
                         (device (uuid "1234-ABCD" 'fat))
                         (mount-point "/boot/efi")
                         (type "vfat")))
                 %base-file-systems))

  (users (cons (user-account
                (name "alice")
                (comment "Bob's sister")
                (group "users")
                (supplementary-groups '("wheel" "netdev"
                                        "audio" "video")))
               %base-user-accounts))

  ;; Add a bunch of window managers; we can choose one at
  ;; the log-in screen with F1.
  (packages (append (list
                     ;; window managers
                     ratpoison i3-wm i3status dmenu
                     emacs emacs-exwm emacs-desktop-environment
                     ;; terminal emulator
                     xterm
                     ;; for HTTPS access
                     nss-certs)
                    %base-packages))

  ;; Use the "desktop" services, which include the X11
  ;; log-in service, networking with NetworkManager, and more.
  (services %desktop-services)

  ;; Allow resolution of '.local' host names with mDNS.
  (name-service-switch %mdns-host-lookup-nss))

This example refers to the /boot/efi file system by its UUID, 1234-ABCD. Replace this UUID with the right UUID on your system, as returned by the blkid command.

See Сервисы рабочего стола, for the exact list of services provided by %desktop-services. See Сертификаты X.509, for background information about the nss-certs package that is used here.

Again, %desktop-services is just a list of service objects. If you want to remove services from there, you can do so using the procedures for list filtering (see SRFI-1 Filtering and Partitioning in GNU Guile Reference Manual). For instance, the following expression returns a list that contains all the services in %desktop-services minus the Avahi service:

Alternatively, the modify-services macro can be used:

Instantiating the System

Assuming the operating-system declaration is stored in the my-system-config.scm file, the guix system reconfigure my-system-config.scm command instantiates that configuration, and makes it the default GRUB boot entry (see Invoking guix system).

Примечание: We recommend that you keep this my-system-config.scm file safe and under version control to easily track changes to your configuration.

The normal way to change the system configuration is by updating this file and re-running guix system reconfigure. One should never have to touch files in /etc or to run commands that modify the system state such as useradd or grub-install. In fact, you must avoid that since that would not only void your warranty but also prevent you from rolling back to previous versions of your system, should you ever need to.

Speaking of roll-back, each time you run guix system reconfigure, a new generation of the system is created—without modifying or deleting previous generations. Old system generations get an entry in the bootloader boot menu, allowing you to boot them in case something went wrong with the latest generation. Reassuring, no? The guix system list-generations command lists the system generations available on disk. It is also possible to roll back the system via the commands guix system roll-back and guix system switch-generation.

Although the guix system reconfigure command will not modify previous generations, you must take care when the current generation is not the latest (e.g., after invoking guix system roll-back), since the operation might overwrite a later generation (see Invoking guix system).

The Programming Interface

At the Scheme level, the bulk of an operating-system declaration is instantiated with the following monadic procedure (see Устройство склада):

Monadic Procedure: operating-system-derivation os

Return a derivation that builds os, an operating-system object (see Деривации).

The output of the derivation is a single directory that refers to all the packages, configuration files, and other supporting files needed to instantiate os.

This procedure is provided by the (gnu system) module. Along with (gnu services) (see Сервисы), this module contains the guts of Guix System. Make sure to visit it!


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