Cargador de arranque

El campo bootloader describe el método que será usado para arrancar su sistema. Las máquinas basadas en procesadores Intel pueden arrancar en el “obsoleto” modo BIOS, como en el ejemplo previo. No obstante, máquinas más recientes usan la Interfaz Unificada Extensible de Firmware (UEFI) para arrancar. En ese caso, el capo bootloader debe contener algo parecido a esto:

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

See Configuración del gestor de arranque, para más información sobre las opciones de configuración disponibles.

Paquetes visibles globalmente

The packages field lists packages that will be globally visible on the system, for all user accounts—i.e., in every user’s PATH environment variable—in addition to the per-user profiles (see Invocación de guix package). The %base-packages variable provides all the tools one would expect for basic user and administrator tasks—including the GNU Core Utilities, the GNU Networking Utilities, the mg lightweight text editor, find, grep, etc. The example above adds GNU Screen to those, taken from the (gnu packages screen) module (see Módulos de paquetes). The (list package output) syntax can be used to add a specific output of a package:

(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 specifications->packages procedure from the (gnu packages) module. For example:

(use-modules (gnu packages))

(operating-system
  ;; ...
  (packages (append (specifications->packages
                      '("git" "git:send-email"))
                    %base-packages)))

Servicios del sistema

El campo services enumera los servicios del sistema disponibles cuando el sistema arranque (see Servicios). La declaración operating-system previa especifica que, además de los servicios básicos, queremos que el daemon de shell seguro OpenSSH espere conexiones por el puerto 2222 (see openssh-service-type). En su implementación, openssh-service-type prepara todo para que sshd se inicie con las opciones de la línea de órdenes adecuadas, posiblemente generando bajo demanda los archivos de configuración necesarios (see Definición de servicios).

De manera ocasional, en vez de usar los servicios básicos tal y como vienen, puede querer personalizarlos. Para hacerlo, use modify-services (see modify-services) para modificar la lista.

Por ejemplo, supongamos que quiere modificar guix-daemon y Mingetty (el punto de acceso al sistema por consola) en la lista %base-services (see %base-services). Para hacerlo, puede escribir lo siguiente en su declaración de sistema operativo:

(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 %mis-servicios))

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 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 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))

Un sistema gráfico con una selección de gestores de ventanas ligeros en vez de entornos de escritorio completos podría ser así:

;; -*- 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 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)
                    %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))

Este ejemplo se refiere al sistema de archivos /boot/efi por su UUID 1234-ABCD. Substituya este UUID con el UUID correcto en su sistema, como el devuelto por la orden blkid.

See Servicios de escritorio, for the exact list of services provided by %desktop-services.

De nuevo, %desktop-services es simplemente una lista de objetos de servicios. Si desea borrar servicios de aquí, puede hacerlo usando procedimientos de filtrado de listas (see SRFI-1 Filtering and Partitioning in GNU Guile Reference Manual). Por ejemplo, la siguiente expresión devuelve una lista que contiene todos los servicios en %desktop-services excepto el servicio Avahi:

(remove (lambda (service)
          (eq? (service-kind service) avahi-service-type))
        %desktop-services)

Alternatively, the modify-services macro can be used:

(modify-services %desktop-services
  (delete avahi-service-type))

Inspecting Services

As you work on your system configuration, you might wonder why some system service doesn’t show up or why the system is not as you expected. There are several ways to inspect and troubleshoot problems.

First, you can inspect the dependency graph of Shepherd services like so:

guix system shepherd-graph /etc/config.scm | \
  guix shell xdot -- xdot -

This lets you visualize the Shepherd services as defined in /etc/config.scm. Each box is a service as would be shown by sudo herd status on the running system, and each arrow denotes a dependency (in the sense that if service A depends on B, then B must be started before A).

Not all “services” are Shepherd services though, since Guix System uses a broader definition of the term (see Servicios). To visualize system services and their relations at a higher level, run:

guix system extension-graph /etc/config.scm | \
  guix shell xdot -- xdot -

This lets you view the service extension graph: how services “extend” each other, for instance by contributing to their configuration. See Composición de servicios, to understand the meaning of this graph.

Last, you may also find it useful to inspect your system configuration at the REPL (see Using Guix Interactively). Here is an example session:

$ guix repl
scheme@(guix-user)> ,use (gnu)
scheme@(guix-user)> (define os (load "config.scm"))
scheme@(guix-user)> ,pp (map service-kind (operating-system-services os))
$1 = (#<service-type localed cabba93>
      …)

See Referencia de servicios, to learn about the Scheme interface to manipulate and inspect services.

Instanciación del sistema

Assuming the operating-system declaration is stored in the config.scm file, the sudo guix system reconfigure config.scm command instantiates that configuration, and makes it the default boot entry. See Empezando, for an overview.

La manera habitual de cambiar la configuración del sistema es actualizar este archivo y volver a ejecutar guix system reconfigure. Nunca se deberían tocar los archivos en /etc o ejecutar órdenes que modifiquen el estado del sistema como useradd o grub-install. De hecho, debe evitarlo ya que no únicamente anularía su garantía sino que también le impediría volver a una versión previa de su sistema, en caso de necesitarlo.

La interfaz programática

A nivel Scheme, el grueso de una declaración operating-system se instancia con el siguiente procedimiento monádico (see La mónada del almacén):

Procedimiento monádico: operating-system-derivation so

Devuelve una derivación que construye so, un objeto operating-system (see Derivaciones).

La salida de la derivación es un único directorio que hace referencia a todos los paquetes, archivos de configuración y otros archivos auxiliares necesarios para instanciar so.

Este procedimiento se proporciona por el módulo (gnu system). Junto con (gnu services) (see Servicios), este módulo contiene los entresijos del sistema Guix. ¡Asegúrese de echarle un vistazo!