Next: operating-system Reference, Previous: 入门, Up: 系统配置 [Contents][Index]
The previous section showed the overall workflow you would follow when administering a Guix System machine (see 入门). Let’s now see in more detail what goes into the system configuration file.
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 调用guix system), as we’ve seen before. 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) (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. (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. It is 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 meaning of some of the most important fields.
Troubleshooting: The configuration file is a Scheme program and you might get the syntax or semantics wrong as you get started. Syntactic issues such as misplaced parentheses can often be identified by reformatting your file:
guix style -f config.scmThe Cookbook has a short section to get started with the Scheme programming language that explains the fundamentals, which you will find helpful when hacking your configuration. See A Scheme Crash Course in GNU Guix Cookbook.
The bootloader field describes the method that will be used to boot
your system. Machines based on Intel processors can boot in “legacy” BIOS
mode, as in the example above. However, more recent machines rely instead
on the Unified Extensible Firmware Interface (UEFI) to boot. In that
case, the bootloader field should contain something along these
lines:
(bootloader-configuration
(bootloader grub-efi-bootloader)
(targets '("/boot/efi")))
See 引导设置, for more information on the available configuration options.
packages字段列出了会在系统中为所有用户可见的包–换句话说，在每个用户的PATH环境变量中—额外地还在每个用户的profiles中(see Invoking guix package)。%base-packages变量提供了基础的用户和管理工作中会用到的所有工具–包括GNU Core
Utilities，GNU Networking Utilities，mg lightweight text
editor，find，grep等等。上面的示例由(gnu packages
screen)模块(see 软件包模块)将GNU Screen加入其中。可以使用(list
package output)语法来添加软件包的特定输出：
(use-modules (gnu packages)) (use-modules (gnu packages dns)) (operating-system ;; ... (packages (cons (list isc-bind "utils") %base-packages)))
像上面的isc-bind这样通过变量名引用软件包的优点是明确无歧义，同时也可以立即将打字错误等问题诊断为“未绑定变量”。缺点是需要知道哪个模块定义了哪个软件包，并相应地增加use-package-modules的行数。为避免这种情况，可以使用(gnu
packages)模块的specification->package步骤，该过程返回对应给定名称或及版本的最佳软件包：
(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)))
The services field lists system services to be made available
when the system starts (see 服务). 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 定义服务).
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 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))
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 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))
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 桌面服务, for the exact list of services provided by
%desktop-services.
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:
(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))
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 服务). 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 合成服务, to understand the meaning of this graph.
Last, you may also find it useful to inspect your system configuration at the REPL (see 交互式使用 Guix). 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 服务参考, to learn about the Scheme interface to manipulate and inspect services.
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 入门, for an
overview.
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.
At the Scheme level, the bulk of an operating-system declaration is
instantiated with the following monadic procedure (see 仓库monad):
Return a derivation that builds os, an operating-system object
(see Derivations).
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 服务), this module contains the guts of
Guix System. Make sure to visit it!
Next: operating-system Reference, Previous: 入门, Up: 系统配置 [Contents][Index]