gnu: Add maven-core-bootstrap.

[jackhill/guix/guix.git] / gnu / system.scm

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2015, 2016 Alex Kost <alezost@gmail.com>
;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu system)
  #:use-module (guix store)
  #:use-module (guix monads)
  #:use-module (guix gexp)
  #:use-module (guix records)
  #:use-module (guix packages)
  #:use-module (guix derivations)
  #:use-module (guix profiles)
  #:use-module (guix ui)
  #:use-module (gnu packages base)
  #:use-module (gnu packages bash)
  #:use-module (gnu packages guile)
  #:use-module (gnu packages admin)
  #:use-module (gnu packages linux)
  #:use-module (gnu packages pciutils)
  #:use-module (gnu packages package-management)
  #:use-module (gnu packages less)
  #:use-module (gnu packages zile)
  #:use-module (gnu packages nano)
  #:use-module (gnu packages gawk)
  #:use-module (gnu packages man)
  #:use-module (gnu packages texinfo)
  #:use-module (gnu packages compression)
  #:use-module (gnu packages firmware)
  #:use-module (gnu services)
  #:use-module (gnu services shepherd)
  #:use-module (gnu services base)
  #:use-module (gnu bootloader)
  #:use-module (gnu system shadow)
  #:use-module (gnu system nss)
  #:use-module (gnu system locale)
  #:use-module (gnu system pam)
  #:use-module (gnu system linux-initrd)
  #:use-module (gnu system uuid)
  #:use-module (gnu system file-systems)
  #:use-module (gnu system mapped-devices)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (rnrs bytevectors)
  #:export (operating-system
            operating-system?

            operating-system-bootloader
            operating-system-services
            operating-system-user-services
            operating-system-packages
            operating-system-host-name
            operating-system-hosts-file
            operating-system-kernel
            operating-system-kernel-file
            operating-system-kernel-arguments
            operating-system-initrd-modules
            operating-system-initrd
            operating-system-users
            operating-system-groups
            operating-system-issue
            operating-system-timezone
            operating-system-locale
            operating-system-locale-definitions
            operating-system-locale-libcs
            operating-system-mapped-devices
            operating-system-file-systems
            operating-system-store-file-system
            operating-system-user-mapped-devices
            operating-system-boot-mapped-devices
            operating-system-activation-script
            operating-system-user-accounts
            operating-system-shepherd-service-names
            operating-system-user-kernel-arguments

            operating-system-derivation
            operating-system-profile
            operating-system-bootcfg
            operating-system-etc-directory
            operating-system-locale-directory
            operating-system-boot-script

            system-linux-image-file-name

            boot-parameters
            boot-parameters?
            boot-parameters-label
            boot-parameters-root-device
            boot-parameters-bootloader-name
            boot-parameters-store-device
            boot-parameters-store-mount-point
            boot-parameters-kernel
            boot-parameters-kernel-arguments
            boot-parameters-initrd
            read-boot-parameters
            read-boot-parameters-file
            boot-parameters->menu-entry

            local-host-aliases
            %setuid-programs
            %base-packages
            %base-firmware))

;;; Commentary:
;;;
;;; This module supports whole-system configuration.
;;;
;;; Code:

(define (bootable-kernel-arguments kernel-arguments system.drv root-device)
  "Prepend extra arguments to KERNEL-ARGUMENTS that allow SYSTEM.DRV to be
booted from ROOT-DEVICE"
  (cons* (string-append "--root="
                        (cond ((uuid? root-device)

                               ;; Note: Always use the DCE format because that's
                               ;; what (gnu build linux-boot) expects for the
                               ;; '--root' kernel command-line option.
                               (uuid->string (uuid-bytevector root-device)
                                             'dce))
                              ((file-system-label? root-device)
                               (file-system-label->string root-device))
                              (else root-device)))
         #~(string-append "--system=" #$system.drv)
         #~(string-append "--load=" #$system.drv "/boot")
         kernel-arguments))

;; System-wide configuration.
;; TODO: Add per-field docstrings/stexi.
(define-record-type* <operating-system> operating-system
  make-operating-system
  operating-system?
  (kernel operating-system-kernel                 ; package
          (default linux-libre))
  (kernel-arguments operating-system-user-kernel-arguments
                    (default '()))                ; list of gexps/strings
  (bootloader operating-system-bootloader)        ; <bootloader-configuration>

  (initrd operating-system-initrd                 ; (list fs) -> M derivation
          (default base-initrd))
  (initrd-modules operating-system-initrd-modules ; list of strings
                  (thunked)                       ; it's system-dependent
                  (default %base-initrd-modules))

  (firmware operating-system-firmware             ; list of packages
            (default %base-firmware))

  (host-name operating-system-host-name)          ; string
  (hosts-file operating-system-hosts-file         ; file-like | #f
              (default #f))

  (mapped-devices operating-system-mapped-devices ; list of <mapped-device>
                  (default '()))
  (file-systems operating-system-file-systems)    ; list of fs
  (swap-devices operating-system-swap-devices     ; list of strings
                (default '()))

  (users operating-system-users                   ; list of user accounts
         (default %base-user-accounts))
  (groups operating-system-groups                 ; list of user groups
          (default %base-groups))

  (skeletons operating-system-skeletons           ; list of name/monadic value
             (default (default-skeletons)))
  (issue operating-system-issue                   ; string
         (default %default-issue))

  (packages operating-system-packages             ; list of (PACKAGE OUTPUT...)
            (default %base-packages))             ; or just PACKAGE

  (timezone operating-system-timezone)            ; string
  (locale   operating-system-locale               ; string
            (default "en_US.utf8"))
  (locale-definitions operating-system-locale-definitions ; list of <locale-definition>
                      (default %default-locale-definitions))
  (locale-libcs operating-system-locale-libcs     ; list of <packages>
                (default %default-locale-libcs))
  (name-service-switch operating-system-name-service-switch ; <name-service-switch>
                       (default %default-nss))

  (services operating-system-user-services        ; list of monadic services
            (default %base-services))

  (pam-services operating-system-pam-services     ; list of PAM services
                (default (base-pam-services)))
  (setuid-programs operating-system-setuid-programs
                   (default %setuid-programs))    ; list of string-valued gexps

  (sudoers-file operating-system-sudoers-file     ; file-like
                (default %sudoers-specification)))

(define (operating-system-kernel-arguments os system.drv root-device)
  "Return all the kernel arguments, including the ones not specified
directly by the user."
  (bootable-kernel-arguments (operating-system-user-kernel-arguments os)
                             system.drv
                             root-device))

\f
;;;
;;; Boot parameters
;;;

(define-record-type* <boot-parameters>
  boot-parameters make-boot-parameters boot-parameters?
  (label            boot-parameters-label)
  ;; Because we will use the 'store-device' to create the GRUB search command,
  ;; the 'store-device' has slightly different semantics than 'root-device'.
  ;; The 'store-device' can be a file system uuid, a file system label, or #f,
  ;; but it cannot be a device path such as "/dev/sda3", since GRUB would not
  ;; understand that.  The 'root-device', on the other hand, corresponds
  ;; exactly to the device field of the <file-system> object representing the
  ;; OS's root file system, so it might be a device path like "/dev/sda3".
  (root-device      boot-parameters-root-device)
  (bootloader-name  boot-parameters-bootloader-name)
  (store-device     boot-parameters-store-device)
  (store-mount-point boot-parameters-store-mount-point)
  (kernel           boot-parameters-kernel)
  (kernel-arguments boot-parameters-kernel-arguments)
  (initrd           boot-parameters-initrd))

(define (ensure-not-/dev device)
  "If DEVICE starts with a slash, return #f.  This is meant to filter out
Linux device names such as /dev/sda, and to preserve GRUB device names and
file system labels."
  (if (and (string? device) (string-prefix? "/" device))
      #f
      device))

(define (read-boot-parameters port)
  "Read boot parameters from PORT and return the corresponding
<boot-parameters> object or #f if the format is unrecognized."
  (define device-sexp->device
    (match-lambda
      (('uuid (? symbol? type) (? bytevector? bv))
       (bytevector->uuid bv type))
      (('file-system-label (? string? label))
       (file-system-label label))
      ((? bytevector? bv)                         ;old format
       (bytevector->uuid bv 'dce))
      ((? string? device)
       ;; It used to be that we would not distinguish between labels and
       ;; device names.  Try to infer the right thing here.
       (if (string-prefix? "/dev/" device)
           device
           (file-system-label device)))))

  (match (read port)
    (('boot-parameters ('version 0)
                       ('label label) ('root-device root)
                       ('kernel linux)
                       rest ...)
     (boot-parameters
      (label label)
      (root-device (device-sexp->device root))

      (bootloader-name
       (match (assq 'bootloader-name rest)
         ((_ args) args)
         (#f       'grub))) ; for compatibility reasons.

      ;; In the past, we would store the directory name of the kernel instead
      ;; of the absolute file name of its image.  Detect that and correct it.
      (kernel (if (string=? linux (direct-store-path linux))
                  (string-append linux "/"
                                 (system-linux-image-file-name))
                  linux))

      (kernel-arguments
       (match (assq 'kernel-arguments rest)
         ((_ args) args)
         (#f       '())))                         ;the old format

      (initrd
       (match (assq 'initrd rest)
         (('initrd ('string-append directory file)) ;the old format
          (string-append directory file))
         (('initrd (? string? file))
          file)))

      (store-device
       ;; Linux device names like "/dev/sda1" are not suitable GRUB device
       ;; identifiers, so we just filter them out.
       (ensure-not-/dev
        (match (assq 'store rest)
          (('store ('device #f) _ ...)
           root-device)
          (('store ('device device) _ ...)
           (device-sexp->device device))
          (_                                      ;the old format
           root-device))))

      (store-mount-point
       (match (assq 'store rest)
         (('store ('device _) ('mount-point mount-point) _ ...)
          mount-point)
         (_                                       ;the old format
          "/")))))
    (x                                            ;unsupported format
     (warning (G_ "unrecognized boot parameters at '~a'~%")
              (port-filename port))
     #f)))

(define (read-boot-parameters-file system)
  "Read boot parameters from SYSTEM's (system or generation) \"parameters\"
file and returns the corresponding <boot-parameters> object or #f if the
format is unrecognized.
The object has its kernel-arguments extended in order to make it bootable."
  (let* ((file (string-append system "/parameters"))
         (params (call-with-input-file file read-boot-parameters))
         (root (boot-parameters-root-device params))
         (kernel-arguments (boot-parameters-kernel-arguments params)))
    (if params
      (boot-parameters
        (inherit params)
        (kernel-arguments (bootable-kernel-arguments kernel-arguments
                                                     system root)))
      #f)))

(define (boot-parameters->menu-entry conf)
  (menu-entry
   (label (boot-parameters-label conf))
   (device (boot-parameters-store-device conf))
   (device-mount-point (boot-parameters-store-mount-point conf))
   (linux (boot-parameters-kernel conf))
   (linux-arguments (boot-parameters-kernel-arguments conf))
   (initrd (boot-parameters-initrd conf))))


\f
;;;
;;; Services.
;;;

(define (non-boot-file-system-service os)
  "Return the file system service for the file systems of OS that are not
marked as 'needed-for-boot'."
  (define file-systems
    (remove file-system-needed-for-boot?
            (operating-system-file-systems os)))

  (define (device-mappings fs)
    (let ((device (file-system-device fs)))
      (if (string? device)                        ;title is 'device
          (filter (lambda (md)
                    (string=? (string-append "/dev/mapper/"
                                             (mapped-device-target md))
                              device))
                  (operating-system-mapped-devices os))
          '())))

  (define (add-dependencies fs)
    ;; Add the dependencies due to device mappings to FS.
    (file-system
      (inherit fs)
      (dependencies
       (delete-duplicates (append (device-mappings fs)
                                  (file-system-dependencies fs))
                          eq?))))

  (service file-system-service-type
           (map add-dependencies file-systems)))

(define (mapped-device-user device file-systems)
  "Return a file system among FILE-SYSTEMS that uses DEVICE, or #f."
  (let ((target (string-append "/dev/mapper/" (mapped-device-target device))))
    (find (lambda (fs)
            (or (member device (file-system-dependencies fs))
                (and (string? (file-system-device fs))
                     (string=? (file-system-device fs) target))))
          file-systems)))

(define (operating-system-user-mapped-devices os)
  "Return the subset of mapped devices that can be installed in
user-land--i.e., those not needed during boot."
  (let ((devices      (operating-system-mapped-devices os))
        (file-systems (operating-system-file-systems os)))
   (filter (lambda (md)
             (let ((user (mapped-device-user md file-systems)))
               (or (not user)
                   (not (file-system-needed-for-boot? user)))))
           devices)))

(define (operating-system-boot-mapped-devices os)
  "Return the subset of mapped devices that must be installed during boot,
from the initrd."
  (let ((devices      (operating-system-mapped-devices os))
        (file-systems (operating-system-file-systems os)))
   (filter (lambda (md)
             (let ((user (mapped-device-user md file-systems)))
               (and user (file-system-needed-for-boot? user))))
           devices)))

(define (device-mapping-services os)
  "Return the list of device-mapping services for OS as a list."
  (map device-mapping-service
       (operating-system-user-mapped-devices os)))

(define (swap-services os)
  "Return the list of swap services for OS."
  (map swap-service (operating-system-swap-devices os)))

(define* (system-linux-image-file-name #:optional (system (%current-system)))
  "Return the basename of the kernel image file for SYSTEM."
  ;; FIXME: Evaluate the conditional based on the actual current system.
  (cond
   ((string-prefix? "arm" (%current-system)) "zImage")
   ((string-prefix? "mips" (%current-system)) "vmlinuz")
   ((string-prefix? "aarch64" (%current-system)) "Image")
   (else "bzImage")))

(define (operating-system-kernel-file os)
  "Return an object representing the absolute file name of the kernel image of
OS."
  (file-append (operating-system-kernel os)
               "/" (system-linux-image-file-name os)))

(define* (operating-system-directory-base-entries os #:key container?)
  "Return the basic entries of the 'system' directory of OS for use as the
value of the SYSTEM-SERVICE-TYPE service."
  (let ((locale (operating-system-locale-directory os)))
    (with-monad %store-monad
      (if container?
          (return `(("locale" ,locale)))
          (mlet %store-monad
              ((kernel  ->  (operating-system-kernel os))
               (initrd      (operating-system-initrd-file os))
               (params      (operating-system-boot-parameters-file os)))
            (return `(("kernel" ,kernel)
                      ("parameters" ,params)
                      ("initrd" ,initrd)
                      ("locale" ,locale))))))))   ;used by libc

(define* (essential-services os #:key container?)
  "Return the list of essential services for OS.  These are special services
that implement part of what's declared in OS are responsible for low-level
bookkeeping.  CONTAINER? determines whether to return the list of services for
a container or that of a \"bare metal\" system."
  (define known-fs
    (map file-system-mount-point (operating-system-file-systems os)))

  (let* ((mappings  (device-mapping-services os))
         (root-fs   (root-file-system-service))
         (other-fs  (non-boot-file-system-service os))
         (swaps     (swap-services os))
         (procs     (service user-processes-service-type))
         (host-name (host-name-service (operating-system-host-name os)))
         (entries   (operating-system-directory-base-entries
                     os #:container? container?)))
    (cons* (service system-service-type entries)
           %boot-service

           ;; %SHEPHERD-ROOT-SERVICE must come first so that the gexp that
           ;; execs shepherd comes last in the boot script (XXX).  Likewise,
           ;; the cleanup service must come last so that its gexp runs before
           ;; activation code.
           %shepherd-root-service
           %activation-service
           (service cleanup-service-type #f)

           (pam-root-service (operating-system-pam-services os))
           (account-service (append (operating-system-accounts os)
                                    (operating-system-groups os))
                            (operating-system-skeletons os))
           (operating-system-etc-service os)
           (service fstab-service-type '())
           (session-environment-service
            (operating-system-environment-variables os))
           host-name procs root-fs
           (service setuid-program-service-type
                    (operating-system-setuid-programs os))
           (service profile-service-type
                    (operating-system-packages os))
           other-fs
           (append mappings swaps

                   ;; Add the firmware service, unless we are building for a
                   ;; container.
                   (if container?
                       '()
                       (list %linux-bare-metal-service
                             (service firmware-service-type
                                      (operating-system-firmware os))))))))

(define* (operating-system-services os #:key container?)
  "Return all the services of OS, including \"internal\" services that do not
explicitly appear in OS."
  (instantiate-missing-services
   (append (operating-system-user-services os)
           (essential-services os #:container? container?))))

\f
;;;
;;; /etc.
;;;

(define %base-firmware
  ;; Firmware usable by default.
  (list ath9k-htc-firmware
        openfwwf-firmware))

(define %base-packages
  ;; Default set of packages globally visible.  It should include anything
  ;; required for basic administrator tasks.
  (cons* procps psmisc which less zile nano
         pciutils usbutils
         util-linux
         inetutils isc-dhcp
         (@ (gnu packages admin) shadow)          ;for 'passwd'

         ;; wireless-tools is deprecated in favor of iw, but it's still what
         ;; many people are familiar with, so keep it around.
         iw wireless-tools

         iproute
         net-tools                        ; XXX: remove when Inetutils suffices
         man-db
         info-reader                     ;the standalone Info reader (no Perl)

         ;; The 'sudo' command is already in %SETUID-PROGRAMS, but we also
         ;; want the other commands and the man pages (notably because
         ;; auto-completion in Emacs shell relies on man pages.)
         sudo

         ;; Get 'insmod' & co. from kmod, not module-init-tools, since udev
         ;; already depends on it anyway.
         kmod eudev

         e2fsprogs kbd

         bash-completion

         ;; XXX: We don't use (canonical-package guile-2.2) here because that
         ;; would create a collision in the global profile between the GMP
         ;; variant propagated by 'guile-final' and the GMP variant propagated
         ;; by 'gnutls', itself propagated by 'guix'.
         guile-2.2

         ;; The packages below are also in %FINAL-INPUTS, so take them from
         ;; there to avoid duplication.
         (map canonical-package
              (list bash coreutils findutils grep sed
                    diffutils patch gawk tar gzip bzip2 xz lzip))))

(define %default-issue
  ;; Default contents for /etc/issue.
  "
This is the GNU system.  Welcome.\n")

(define (local-host-aliases host-name)
  "Return aliases for HOST-NAME, to be used in /etc/hosts."
  (string-append "127.0.0.1 localhost " host-name "\n"
                 "::1       localhost " host-name "\n"))

(define (default-/etc/hosts host-name)
  "Return the default /etc/hosts file."
  (plain-file "hosts" (local-host-aliases host-name)))

(define* (operating-system-etc-service os)
  "Return a <service> that builds containing the static part of the /etc
directory."
  (let ((login.defs
          (plain-file "login.defs"
                      (string-append
                        "# Default paths for non-login shells started by su(1).\n"
                        "ENV_PATH    /run/setuid-programs:"
                        "/run/current-system/profile/bin:"
                        "/run/current-system/profile/sbin\n"
                        "ENV_SUPATH  /run/setuid-programs:"
                        "/run/current-system/profile/bin:"
                        "/run/current-system/profile/sbin\n")))

        (issue      (plain-file "issue" (operating-system-issue os)))
        (nsswitch   (plain-file "nsswitch.conf"
                                (name-service-switch->string
                                 (operating-system-name-service-switch os))))

        ;; Startup file for POSIX-compliant login shells, which set system-wide
        ;; environment variables.
        (profile    (mixed-text-file "profile"  "\
# Crucial variables that could be missing in the profiles' 'etc/profile'
# because they would require combining both profiles.
# FIXME: See <http://bugs.gnu.org/20255>.
export MANPATH=$HOME/.guix-profile/share/man:/run/current-system/profile/share/man
export INFOPATH=$HOME/.guix-profile/share/info:/run/current-system/profile/share/info
export XDG_DATA_DIRS=$HOME/.guix-profile/share:/run/current-system/profile/share
export XDG_CONFIG_DIRS=$HOME/.guix-profile/etc/xdg:/run/current-system/profile/etc/xdg

# Make sure libXcursor finds cursors installed into user or system profiles.  See <http://bugs.gnu.org/24445>
export XCURSOR_PATH=$HOME/.icons:$HOME/.guix-profile/share/icons:/run/current-system/profile/share/icons

# Ignore the default value of 'PATH'.
unset PATH

# Load the system profile's settings.
GUIX_PROFILE=/run/current-system/profile ; \\
. /run/current-system/profile/etc/profile

# Prepend setuid programs.
export PATH=/run/setuid-programs:$PATH

# Since 'lshd' does not use pam_env, /etc/environment must be explicitly
# loaded when someone logs in via SSH.  See <http://bugs.gnu.org/22175>.
# We need 'PATH' to be defined here, for 'cat' and 'cut'.  Do this before
# reading the user's 'etc/profile' to allow variables to be overridden.
if [ -f /etc/environment -a -n \"$SSH_CLIENT\" \\
     -a -z \"$LINUX_MODULE_DIRECTORY\" ]
then
  . /etc/environment
  export `cat /etc/environment | cut -d= -f1`
fi

# Arrange so that ~/.config/guix/current comes first.
for profile in \"$HOME/.guix-profile\" \"$HOME/.config/guix/current\"
do
  if [ -f \"$profile/etc/profile\" ]
  then
    # Load the user profile's settings.
    GUIX_PROFILE=\"$profile\" ; \\
    . \"$profile/etc/profile\"
  else
    # At least define this one so that basic things just work
    # when the user installs their first package.
    export PATH=\"$profile/bin:$PATH\"
  fi
done

# Arrange so that ~/.config/guix/current/share/info comes first.
export INFOPATH=\"$HOME/.config/guix/current/share/info:$INFOPATH\"

# Set the umask, notably for users logging in via 'lsh'.
# See <http://bugs.gnu.org/22650>.
umask 022

# Allow Hunspell-based applications (IceCat, LibreOffice, etc.) to
# find dictionaries.
export DICPATH=\"$HOME/.guix-profile/share/hunspell:/run/current-system/profile/share/hunspell\"

# Allow GStreamer-based applications to find plugins.
export GST_PLUGIN_PATH=\"$HOME/.guix-profile/lib/gstreamer-1.0\"

if [ -n \"$BASH_VERSION\" -a -f /etc/bashrc ]
then
  # Load Bash-specific initialization code.
  . /etc/bashrc
fi
"))

        (bashrc    (plain-file "bashrc" "\
# Bash-specific initialization.

# The 'bash-completion' package.
if [ -f /run/current-system/profile/etc/profile.d/bash_completion.sh ]
then
  # Bash-completion sources ~/.bash_completion.  It installs a dynamic
  # completion loader that searches its own completion files as well
  # as those in ~/.guix-profile and /run/current-system/profile.
  source /run/current-system/profile/etc/profile.d/bash_completion.sh
fi\n")))
    (etc-service
     `(("services" ,(file-append net-base "/etc/services"))
       ("protocols" ,(file-append net-base "/etc/protocols"))
       ("rpc" ,(file-append net-base "/etc/rpc"))
       ("login.defs" ,#~#$login.defs)
       ("issue" ,#~#$issue)
       ("nsswitch.conf" ,#~#$nsswitch)
       ("profile" ,#~#$profile)
       ("bashrc" ,#~#$bashrc)
       ("hosts" ,#~#$(or (operating-system-hosts-file os)
                         (default-/etc/hosts (operating-system-host-name os))))
       ;; Write the operating-system-host-name to /etc/hostname to prevent
       ;; NetworkManager from changing the system's hostname when connecting
       ;; to certain networks.  Some discussion at
       ;; https://lists.gnu.org/archive/html/help-guix/2017-09/msg00037.html
       ("hostname" ,(plain-file "hostname" (operating-system-host-name os)))
       ("localtime" ,(file-append tzdata "/share/zoneinfo/"
                                  (operating-system-timezone os)))
       ("sudoers" ,(operating-system-sudoers-file os))))))

(define %root-account
  ;; Default root account.
  (user-account
   (name "root")
   (password "")
   (uid 0) (group "root")
   (comment "System administrator")
   (home-directory "/root")))

(define (operating-system-accounts os)
  "Return the user accounts for OS, including an obligatory 'root' account,
and excluding accounts requested by services."
  ;; Make sure there's a root account.
  (if (find (lambda (user)
              (and=> (user-account-uid user) zero?))
            (operating-system-users os))
      (operating-system-users os)
      (cons %root-account (operating-system-users os))))

(define (maybe-string->file file-name thing)
  "If THING is a string, return a <plain-file> with THING as its content.
Otherwise just return THING.

This is for backward-compatibility of fields that used to be strings and are
now file-like objects.."
  (match thing
    ((? string?)
     (warning (G_ "using a string for file '~a' is deprecated; \
use 'plain-file' instead~%")
              file-name)
     (plain-file file-name thing))
    (x
     x)))

(define (maybe-file->monadic file-name thing)
  "If THING is a value in %STORE-MONAD, return it as is; otherwise return
THING in the %STORE-MONAD.

This is for backward-compatibility of fields that used to be monadic values
and are now file-like objects."
  (with-monad %store-monad
    (match thing
      ((? procedure?)
       (warning (G_ "using a monadic value for '~a' is deprecated; \
use 'plain-file' instead~%")
                file-name)
       thing)
      (x
       (return x)))))

(define (operating-system-etc-directory os)
  "Return that static part of the /etc directory of OS."
  (etc-directory
   (fold-services (operating-system-services os)
                  #:target-type etc-service-type)))

(define (operating-system-environment-variables os)
  "Return the environment variables of OS for
@var{session-environment-service-type}, to be used in @file{/etc/environment}."
  `(("LANG" . ,(operating-system-locale os))
    ;; Note: No need to set 'TZ' since (1) we provide /etc/localtime, and (2)
    ;; it doesn't work for setuid binaries.  See <https://bugs.gnu.org/29212>.
    ("TZDIR" . ,(file-append tzdata "/share/zoneinfo"))
    ;; Tell 'modprobe' & co. where to look for modules.
    ("LINUX_MODULE_DIRECTORY" . "/run/booted-system/kernel/lib/modules")
    ;; These variables are honored by OpenSSL (libssl) and Git.
    ("SSL_CERT_DIR" . "/etc/ssl/certs")
    ("SSL_CERT_FILE" . "/etc/ssl/certs/ca-certificates.crt")
    ("GIT_SSL_CAINFO" . "/etc/ssl/certs/ca-certificates.crt")

    ;; 'GTK_DATA_PREFIX' must name one directory where GTK+ themes are
    ;; searched for.
    ("GTK_DATA_PREFIX" . "/run/current-system/profile")

    ;; By default, applications that use D-Bus, such as Emacs, abort at startup
    ;; when /etc/machine-id is missing.  Make sure these warnings are non-fatal.
    ("DBUS_FATAL_WARNINGS" . "0")

    ;; XXX: Normally we wouldn't need to do this, but our glibc@2.23 package
    ;; used to look things up in 'PREFIX/lib/locale' instead of
    ;; '/run/current-system/locale' as was intended.  Keep this hack around so
    ;; that people who still have glibc@2.23-using packages in their profiles
    ;; can use them correctly.
    ;; TODO: Remove when glibc@2.23 is long gone.
    ("GUIX_LOCPATH" . "/run/current-system/locale")))

(define %setuid-programs
  ;; Default set of setuid-root programs.
  (let ((shadow (@ (gnu packages admin) shadow)))
    (list (file-append shadow "/bin/passwd")
          (file-append shadow "/bin/su")
          (file-append shadow "/bin/newuidmap")
          (file-append shadow "/bin/newgidmap")
          (file-append inetutils "/bin/ping")
          (file-append inetutils "/bin/ping6")
          (file-append sudo "/bin/sudo")
          (file-append fuse "/bin/fusermount"))))

(define %sudoers-specification
  ;; Default /etc/sudoers contents: 'root' and all members of the 'wheel'
  ;; group can do anything.  See
  ;; <http://www.sudo.ws/sudo/man/1.8.10/sudoers.man.html>.
  ;; TODO: Add a declarative API.
  (plain-file "sudoers" "\
root ALL=(ALL) ALL
%wheel ALL=(ALL) ALL\n"))

(define* (operating-system-activation-script os #:key container?)
  "Return the activation script for OS---i.e., the code that \"activates\" the
stateful part of OS, including user accounts and groups, special directories,
etc."
  (let* ((services   (operating-system-services os #:container? container?))
         (activation (fold-services services
                                    #:target-type activation-service-type)))
    (activation-service->script activation)))

(define* (operating-system-boot-script os #:key container?)
  "Return the boot script for OS---i.e., the code started by the initrd once
we're running in the final root.  When CONTAINER? is true, skip all
hardware-related operations as necessary when booting a Linux container."
  (let* ((services (operating-system-services os #:container? container?))
         (boot     (fold-services services #:target-type boot-service-type)))
    ;; BOOT is the script as a monadic value.
    (service-value boot)))

(define (operating-system-user-accounts os)
  "Return the list of user accounts of OS."
  (let* ((services (operating-system-services os))
         (account  (fold-services services
                                  #:target-type account-service-type)))
    (filter user-account?
            (service-value account))))

(define (operating-system-shepherd-service-names os)
  "Return the list of Shepherd service names for OS."
  (append-map shepherd-service-provision
              (service-value
               (fold-services (operating-system-services os)
                              #:target-type
                              shepherd-root-service-type))))

(define* (operating-system-derivation os #:key container?)
  "Return a derivation that builds OS."
  (let* ((services (operating-system-services os #:container? container?))
         (system   (fold-services services)))
    ;; SYSTEM contains the derivation as a monadic value.
    (service-value system)))

(define* (operating-system-profile os #:key container?)
  "Return a derivation that builds the system profile of OS."
  (mlet* %store-monad
      ((services -> (operating-system-services os #:container? container?))
       (profile (fold-services services
                               #:target-type profile-service-type)))
    (match profile
      (("profile" profile)
       (return profile)))))

(define (operating-system-root-file-system os)
  "Return the root file system of OS."
  (find (lambda (fs)
          (string=? "/" (file-system-mount-point fs)))
        (operating-system-file-systems os)))

(define (operating-system-initrd-file os)
  "Return a gexp denoting the initrd file of OS."
  (define boot-file-systems
    (filter file-system-needed-for-boot?
            (operating-system-file-systems os)))

  (define mapped-devices
    (operating-system-boot-mapped-devices os))

  (define make-initrd
    (operating-system-initrd os))

  (mlet %store-monad ((initrd (make-initrd boot-file-systems
                                           #:linux (operating-system-kernel os)
                                           #:linux-modules
                                           (operating-system-initrd-modules os)
                                           #:mapped-devices mapped-devices)))
    (return (file-append initrd "/initrd"))))

(define (locale-name->definition* name)
  "Variant of 'locale-name->definition' that raises an error upon failure."
  (match (locale-name->definition name)
    (#f
     (raise (condition
             (&message
              (message (format #f (G_ "~a: invalid locale name") name))))))
    (def def)))

(define (operating-system-locale-directory os)
  "Return the directory containing the locales compiled for the definitions
listed in OS.  The C library expects to find it under
/run/current-system/locale."
  (define name
    (operating-system-locale os))

  (define definitions
    ;; While we're at it, check whether NAME is defined and add it if needed.
    (if (member name (map locale-definition-name
                          (operating-system-locale-definitions os)))
        (operating-system-locale-definitions os)
        (cons (locale-name->definition* name)
              (operating-system-locale-definitions os))))

  (locale-directory definitions
                    #:libcs (operating-system-locale-libcs os)))

(define (kernel->boot-label kernel)
  "Return a label for the bootloader menu entry that boots KERNEL."
  (string-append "GNU with "
                 (string-titlecase (package-name kernel)) " "
                 (package-version kernel)
                 " (beta)"))

(define (store-file-system file-systems)
  "Return the file system object among FILE-SYSTEMS that contains the store."
  (match (filter (lambda (fs)
                   (and (file-system-mount? fs)
                        (not (memq 'bind-mount (file-system-flags fs)))
                        (string-prefix? (file-system-mount-point fs)
                                        (%store-prefix))))
                 file-systems)
    ((and candidates (head . tail))
     (reduce (lambda (fs1 fs2)
               (if (> (string-length (file-system-mount-point fs1))
                      (string-length (file-system-mount-point fs2)))
                   fs1
                   fs2))
             head
             candidates))))

(define (operating-system-store-file-system os)
  "Return the file system that contains the store of OS."
  (store-file-system (operating-system-file-systems os)))

(define* (operating-system-bootcfg os #:optional (old-entries '()))
  "Return the bootloader configuration file for OS.  Use OLD-ENTRIES
(which is a list of <menu-entry>) to populate the \"old entries\" menu."
  (mlet* %store-monad
      ((system      (operating-system-derivation os))
       (root-fs ->  (operating-system-root-file-system os))
       (root-device -> (file-system-device root-fs))
       (params (operating-system-boot-parameters os system root-device))
       (entry -> (boot-parameters->menu-entry params))
       (bootloader-conf -> (operating-system-bootloader os)))
    ((bootloader-configuration-file-generator
      (bootloader-configuration-bootloader bootloader-conf))
     bootloader-conf (list entry) #:old-entries old-entries)))

(define (operating-system-boot-parameters os system.drv root-device)
  "Return a monadic <boot-parameters> record that describes the boot parameters
of OS.  SYSTEM.DRV is either a derivation or #f.  If it's a derivation, adds
kernel arguments for that derivation to <boot-parameters>."
  (mlet* %store-monad
      ((initrd (operating-system-initrd-file os))
       (store -> (operating-system-store-file-system os))
       (bootloader  -> (bootloader-configuration-bootloader
                        (operating-system-bootloader os)))
       (bootloader-name -> (bootloader-name bootloader))
       (label -> (kernel->boot-label (operating-system-kernel os))))
    (return (boot-parameters
             (label label)
             (root-device root-device)
             (kernel (operating-system-kernel-file os))
             (kernel-arguments
              (if system.drv
                (operating-system-kernel-arguments os system.drv root-device)
                (operating-system-user-kernel-arguments os)))
             (initrd initrd)
             (bootloader-name bootloader-name)
             (store-device (ensure-not-/dev (file-system-device store)))
             (store-mount-point (file-system-mount-point store))))))

(define (device->sexp device)
  "Serialize DEVICE as an sexp (really, as an object with a read syntax.)"
  (match device
    ((? uuid? uuid)
     `(uuid ,(uuid-type uuid) ,(uuid-bytevector uuid)))
    ((? file-system-label? label)
     `(file-system-label ,(file-system-label->string label)))
    (_
     device)))

(define* (operating-system-boot-parameters-file os #:optional (system.drv #f))
   "Return a file that describes the boot parameters of OS.  The primary use of
this file is the reconstruction of GRUB menu entries for old configurations.
SYSTEM.DRV is optional.  If given, adds kernel arguments for that system to the
returned file (since the returned file is then usually stored into the
content-addressed \"system\" directory, it's usually not a good idea
to give it because the content hash would change by the content hash
being stored into the \"parameters\" file)."
  (mlet* %store-monad ((root -> (operating-system-root-file-system os))
                       (device -> (file-system-device root))
                       (params (operating-system-boot-parameters os
                                                                 system.drv
                                                                 device)))
     (gexp->file "parameters"
                 #~(boot-parameters
                    (version 0)
                    (label #$(boot-parameters-label params))
                    (root-device
                     #$(device->sexp
                        (boot-parameters-root-device params)))
                    (kernel #$(boot-parameters-kernel params))
                    (kernel-arguments
                     #$(boot-parameters-kernel-arguments params))
                    (initrd #$(boot-parameters-initrd params))
                    (bootloader-name #$(boot-parameters-bootloader-name params))
                    (store
                     (device
                      #$(device->sexp (boot-parameters-store-device params)))
                     (mount-point #$(boot-parameters-store-mount-point params))))
                 #:set-load-path? #f)))

(define-gexp-compiler (operating-system-compiler (os <operating-system>)
                                                 system target)
  ((store-lift
    (lambda (store)
      ;; XXX: This is not super elegant but we can't pass SYSTEM and TARGET to
      ;; 'operating-system-derivation'.
      (run-with-store store (operating-system-derivation os)
                      #:system system
                      #:target target)))))

;;; system.scm ends here