doc: Mention 'guix lint' and '--list-dependent' in 'HACKING'.
[jackhill/guix/guix.git] / gnu / system.scm
dissimilarity index 76%
index e9ecfd2..2469ade 100644 (file)
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
-;;;
-;;; 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 records)
-  #:use-module (guix packages)
-  #:use-module (guix derivations)
-  #:use-module (gnu packages base)
-  #:use-module (gnu packages bash)
-  #:use-module (gnu packages admin)
-  #:use-module (gnu packages package-management)
-  #:use-module (gnu system dmd)
-  #:use-module (gnu system grub)
-  #:use-module (gnu system shadow)
-  #:use-module (gnu system linux)
-  #:use-module (gnu system linux-initrd)
-  #:use-module (ice-9 match)
-  #:use-module (srfi srfi-1)
-  #:use-module (srfi srfi-26)
-  #:export (operating-system
-            operating-system?
-            operating-system-services
-            operating-system-packages
-
-            operating-system-derivation))
-
-;;; Commentary:
-;;;
-;;; This module supports whole-system configuration.
-;;;
-;;; Code:
-
-;; 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))
-  (bootloader operating-system-bootloader         ; package
-              (default grub))
-  (bootloader-entries operating-system-bootloader-entries ; list
-                      (default '()))
-  (initrd operating-system-initrd                 ; monadic derivation
-          (default (gnu-system-initrd)))
-
-  (host-name operating-system-host-name)          ; string
-
-  (file-systems operating-system-file-systems     ; list of fs
-                (default '()))
-
-  (users operating-system-users                   ; list of user accounts
-         (default '()))
-  (groups operating-system-groups                 ; list of user groups
-          (default (list (user-group
-                          (name "root")
-                          (id 0))
-                         (user-group
-                          (name "users")
-                          (id 100)
-                          (members '("guest"))))))
-
-  (packages operating-system-packages             ; list of (PACKAGE OUTPUT...)
-            (default (list coreutils              ; or just PACKAGE
-                           grep
-                           sed
-                           findutils
-                           guile
-                           bash
-                           (@ (gnu packages dmd) dmd)
-                           guix
-                           tzdata)))
-
-  (timezone operating-system-timezone)            ; string
-  (locale   operating-system-locale)              ; string
-
-  (services operating-system-services             ; list of monadic services
-            (default
-              (let ((motd (text-file "motd" "
-This is the GNU operating system, welcome!\n\n")))
-                (list (mingetty-service "tty1" #:motd motd)
-                      (mingetty-service "tty2" #:motd motd)
-                      (mingetty-service "tty3" #:motd motd)
-                      (mingetty-service "tty4" #:motd motd)
-                      (mingetty-service "tty5" #:motd motd)
-                      (mingetty-service "tty6" #:motd motd)
-                      (syslog-service)
-                      (guix-service)
-                      (nscd-service)
-
-                      ;; QEMU networking settings.
-                      (static-networking-service "eth0" "10.0.2.10"
-                                                 #:name-servers '("10.0.2.3")
-                                                 #:gateway "10.0.2.2"))))))
-
-
-\f
-;;;
-;;; Derivation.
-;;;
-
-(define* (union inputs
-                #:key (guile (%guile-for-build)) (system (%current-system))
-                (name "union"))
-  "Return a derivation that builds the union of INPUTS.  INPUTS is a list of
-input tuples."
-  (define builder
-    '(begin
-       (use-modules (guix build union))
-
-       (setvbuf (current-output-port) _IOLBF)
-       (setvbuf (current-error-port) _IOLBF)
-
-       (let ((output (assoc-ref %outputs "out"))
-             (inputs (map cdr %build-inputs)))
-         (format #t "building union `~a' with ~a packages...~%"
-                 output (length inputs))
-         (union-build output inputs))))
-
-  (mlet %store-monad
-      ((inputs (sequence %store-monad
-                         (map (match-lambda
-                               ((or ((? package? p)) (? package? p))
-                                (mlet %store-monad
-                                    ((drv (package->derivation p system)))
-                                  (return `(,name ,drv))))
-                               (((? package? p) output)
-                                (mlet %store-monad
-                                    ((drv (package->derivation p system)))
-                                  (return `(,name ,drv ,output))))
-                               (x
-                                (return x)))
-                              inputs))))
-    (derivation-expression name builder
-                           #:system system
-                           #:inputs inputs
-                           #:modules '((guix build union))
-                           #:guile-for-build guile)))
-
-(define* (file-union files
-                     #:key (inputs '()) (name "file-union"))
-  "Return a derivation that builds a directory containing all of FILES.  Each
-item in FILES must be a list where the first element is the file name to use
-in the new directory, and the second element is the target file.
-
-The subset of FILES corresponding to plain store files is automatically added
-as an inputs; additional inputs, such as derivations, are taken from INPUTS."
-  (mlet %store-monad ((inputs (lower-inputs inputs)))
-    (let* ((outputs (append-map (match-lambda
-                                 ((_ (? derivation? drv))
-                                  (list (derivation->output-path drv)))
-                                 ((_ (? derivation? drv) sub-drv ...)
-                                  (map (cut derivation->output-path drv <>)
-                                       sub-drv))
-                                 (_ '()))
-                                inputs))
-           (inputs   (append inputs
-                             (filter (match-lambda
-                                      ((_ file)
-                                       ;; Elements of FILES that are store
-                                       ;; files and that do not correspond to
-                                       ;; the output of INPUTS are considered
-                                       ;; inputs (still here?).
-                                       (and (direct-store-path? file)
-                                            (not (member file outputs)))))
-                                     files))))
-      (derivation-expression name
-                             `(let ((out (assoc-ref %outputs "out")))
-                                (mkdir out)
-                                (chdir out)
-                                ,@(map (match-lambda
-                                        ((name target)
-                                         `(symlink ,target ,name)))
-                                       files))
-
-                             #:inputs inputs))))
-
-(define (links inputs)
-  "Return a directory with symbolic links to all of INPUTS.  This is
-essentially useful when one wants to keep references to all of INPUTS, be they
-directories or regular files."
-  (define builder
-    '(begin
-       (use-modules (srfi srfi-1))
-
-       (let ((out (assoc-ref %outputs "out")))
-         (mkdir out)
-         (chdir out)
-         (fold (lambda (file number)
-                 (symlink file (number->string number))
-                 (+ 1 number))
-               0
-               (map cdr %build-inputs))
-         #t)))
-
-  (mlet %store-monad ((inputs (lower-inputs inputs)))
-    (derivation-expression "links" builder
-                           #:inputs inputs)))
-
-(define* (etc-directory #:key
-                        (locale "C") (timezone "Europe/Paris")
-                        (accounts '())
-                        (groups '())
-                        (pam-services '())
-                        (profile "/var/run/current-system/profile"))
-  "Return a derivation that builds the static part of the /etc directory."
-  (mlet* %store-monad
-      ((services   (package-file net-base "etc/services"))
-       (protocols  (package-file net-base "etc/protocols"))
-       (rpc        (package-file net-base "etc/rpc"))
-       (passwd     (passwd-file accounts))
-       (shadow     (passwd-file accounts #:shadow? #t))
-       (group      (group-file groups))
-       (pam.d      (pam-services->directory pam-services))
-       (login.defs (text-file "login.defs" "# Empty for now.\n"))
-       (issue      (text-file "issue" "
-This is an alpha preview of the GNU system.  Welcome.
-
-This image features the GNU Guix package manager, which was used to
-build it (http://www.gnu.org/software/guix/).  The init system is
-GNU dmd (http://www.gnu.org/software/dmd/).
-
-You can log in as 'guest' or 'root' with no password.
-"))
-
-       ;; Assume TZDATA is installed---e.g., as part of the system packages.
-       ;; Users can choose not to have it.
-       (tzdir      (package-file tzdata "share/zoneinfo"))
-
-       ;; TODO: Generate bashrc from packages' search-paths.
-       (bashrc    (text-file "bashrc" (string-append "
-export PS1='\\u@\\h\\$ '
-
-export LC_ALL=\"" locale "\"
-export TZ=\"" timezone "\"
-export TZDIR=\"" tzdir "\"
-
-export PATH=$HOME/.guix-profile/bin:" profile "/bin:" profile "/sbin
-export CPATH=$HOME/.guix-profile/include:" profile "/include
-export LIBRARY_PATH=$HOME/.guix-profile/lib:" profile "/lib
-alias ls='ls -p --color'
-alias ll='ls -l'
-")))
-
-       (files -> `(("services" ,services)
-                   ("protocols" ,protocols)
-                   ("rpc" ,rpc)
-                   ("pam.d" ,(derivation->output-path pam.d))
-                   ("login.defs" ,login.defs)
-                   ("issue" ,issue)
-                   ("profile" ,bashrc)
-                   ("passwd" ,passwd)
-                   ("shadow" ,shadow)
-                   ("group" ,group))))
-    (file-union files
-                #:inputs `(("net" ,net-base)
-                           ("pam.d" ,pam.d))
-                #:name "etc")))
-
-(define (operating-system-derivation os)
-  "Return a derivation that builds OS."
-  (mlet* %store-monad
-      ((services (sequence %store-monad
-                           (cons (host-name-service
-                                  (operating-system-host-name os))
-                                 (operating-system-services os))))
-       (pam-services ->
-                     ;; Services known to PAM.
-                     (delete-duplicates
-                      (cons %pam-other-services
-                            (append-map service-pam-services services))))
-
-       (bash-file (package-file bash "bin/bash"))
-       (dmd-file  (package-file (@ (gnu packages admin) dmd) "bin/dmd"))
-       (accounts -> (cons (user-account
-                            (name "root")
-                            (password "")
-                            (uid 0) (gid 0)
-                            (comment "System administrator")
-                            (home-directory "/"))
-                          (append (operating-system-users os)
-                                  (append-map service-user-accounts
-                                              services))))
-       (groups   -> (append (operating-system-groups os)
-                            (append-map service-user-groups services)))
-       (packages -> (operating-system-packages os))
-
-       ;; TODO: Replace with a real profile with a manifest.
-       (profile-drv (union packages
-                           #:name "default-profile"))
-       (profile ->  (derivation->output-path profile-drv))
-       (etc-drv     (etc-directory #:accounts accounts #:groups groups
-                                   #:pam-services pam-services
-                                   #:locale (operating-system-locale os)
-                                   #:timezone (operating-system-timezone os)
-                                   #:profile profile))
-       (etc     ->  (derivation->output-path etc-drv))
-       (dmd-conf  (dmd-configuration-file services etc))
-
-
-       (boot     (text-file "boot"
-                            (object->string
-                             `(execl ,dmd-file "dmd"
-                                     "--config" ,dmd-conf))))
-       (kernel  ->  (operating-system-kernel os))
-       (kernel-dir  (package-file kernel))
-       (initrd      (operating-system-initrd os))
-       (initrd-file -> (string-append (derivation->output-path initrd)
-                                      "/initrd"))
-       (entries ->  (list (menu-entry
-                           (label (string-append
-                                   "GNU system with "
-                                   (package-full-name kernel)
-                                   " (technology preview)"))
-                           (linux kernel)
-                           (linux-arguments `("--root=/dev/sda1"
-                                              ,(string-append "--load=" boot)))
-                           (initrd initrd-file))))
-       (grub.cfg (grub-configuration-file entries))
-       (extras   (links (delete-duplicates
-                         (append (append-map service-inputs services)
-                                 (append-map user-account-inputs accounts))))))
-    (file-union `(("boot" ,boot)
-                  ("kernel" ,kernel-dir)
-                  ("initrd" ,initrd-file)
-                  ("dmd.conf" ,dmd-conf)
-                  ("profile" ,profile)
-                  ("grub.cfg" ,grub.cfg)
-                  ("etc" ,etc)
-                  ("system-inputs" ,(derivation->output-path extras)))
-                #:inputs `(("kernel" ,kernel)
-                           ("initrd" ,initrd)
-                           ("bash" ,bash)
-                           ("profile" ,profile-drv)
-                           ("etc" ,etc-drv)
-                           ("system-inputs" ,extras))
-                #:name "system")))
-
-;;; system.scm ends here
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; 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 (gnu packages base)
+  #:use-module (gnu packages bash)
+  #:use-module (gnu packages guile)
+  #:use-module (gnu packages which)
+  #:use-module (gnu packages admin)
+  #:use-module (gnu packages linux)
+  #:use-module (gnu packages package-management)
+  #:use-module (gnu packages which)
+  #:use-module (gnu packages less)
+  #:use-module (gnu packages zile)
+  #:use-module (gnu packages nano)
+  #:use-module (gnu packages lsof)
+  #:use-module (gnu services)
+  #:use-module (gnu services dmd)
+  #:use-module (gnu services base)
+  #:use-module (gnu system grub)
+  #:use-module (gnu system shadow)
+  #:use-module (gnu system linux)
+  #:use-module (gnu system linux-initrd)
+  #:use-module (gnu system file-systems)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:export (operating-system
+            operating-system?
+
+            operating-system-bootloader
+            operating-system-services
+            operating-system-user-services
+            operating-system-packages
+            operating-system-host-name
+            operating-system-kernel
+            operating-system-initrd
+            operating-system-users
+            operating-system-groups
+            operating-system-issue
+            operating-system-packages
+            operating-system-timezone
+            operating-system-locale
+            operating-system-file-systems
+            operating-system-activation-script
+
+            operating-system-derivation
+            operating-system-profile
+            operating-system-grub.cfg
+
+            %base-packages))
+
+;;; Commentary:
+;;;
+;;; This module supports whole-system configuration.
+;;;
+;;; Code:
+
+;; 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))
+  (bootloader operating-system-bootloader)        ; <grub-configuration>
+
+  (initrd operating-system-initrd                 ; (list fs) -> M derivation
+          (default base-initrd))
+
+  (host-name operating-system-host-name)          ; string
+
+  (file-systems operating-system-file-systems)    ; list of fs
+
+  (users operating-system-users                   ; list of user accounts
+         (default '()))
+  (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.UTF-8"))
+
+  (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 operating-system-sudoers               ; /etc/sudoers contents
+           (default %sudoers-specification)))
+
+\f
+;;;
+;;; Derivation.
+;;;
+
+(define* (file-union name files)
+  "Return a derivation that builds a directory containing all of FILES.  Each
+item in FILES must be a list where the first element is the file name to use
+in the new directory, and the second element is a gexp denoting the target
+file."
+  (define builder
+    #~(begin
+        (mkdir #$output)
+        (chdir #$output)
+        #$@(map (match-lambda
+                 ((target source)
+                  #~(symlink #$source #$target)))
+                files)))
+
+  (gexp->derivation name builder))
+
+\f
+;;;
+;;; Services.
+;;;
+
+(define (other-file-system-services os)
+  "Return file system services for the file systems of OS that are not marked
+as 'needed-for-boot'."
+  (define file-systems
+    (remove (lambda (fs)
+              (or (file-system-needed-for-boot? fs)
+                  (string=? "/" (file-system-mount-point fs))))
+            (operating-system-file-systems os)))
+
+  (sequence %store-monad
+            (map (match-lambda
+                  (($ <file-system> device title target type flags opts
+                                    #f check? create?)
+                   (file-system-service device target type
+                                        #:title title
+                                        #:check? check?
+                                        #:create-mount-point? create?
+                                        #:options opts
+                                        #:flags flags)))
+                 file-systems)))
+
+(define (essential-services os)
+  "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."
+  (mlet* %store-monad ((root-fs   (root-file-system-service))
+                       (other-fs  (other-file-system-services os))
+                       (procs     (user-processes-service
+                                   (map (compose first service-provision)
+                                        other-fs)))
+                       (host-name (host-name-service
+                                   (operating-system-host-name os))))
+    (return (cons* host-name procs root-fs other-fs))))
+
+(define (operating-system-services os)
+  "Return all the services of OS, including \"internal\" services that do not
+explicitly appear in OS."
+  (mlet %store-monad
+      ((user      (sequence %store-monad (operating-system-user-services os)))
+       (essential (essential-services os)))
+    (return (append essential user))))
+
+\f
+;;;
+;;; /etc.
+;;;
+
+(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
+         (@ (gnu packages admin) dmd) guix
+         lsof                                 ;for Guix's 'list-runtime-roots'
+         util-linux inetutils isc-dhcp
+         net-tools                        ; XXX: remove when Inetutils suffices
+
+         ;; Get 'insmod' & co. from kmod, not module-init-tools, since udev
+         ;; already depends on it anyway.
+         kmod udev
+
+         e2fsprogs kbd
+
+         ;; The packages below are also in %FINAL-INPUTS, so take them from
+         ;; there to avoid duplication.
+         (map canonical-package
+              (list guile-2.0 bash coreutils findutils grep sed))))
+
+(define %default-issue
+  ;; Default contents for /etc/issue.
+  "
+This is the GNU system.  Welcome.\n")
+
+(define* (etc-directory #:key
+                        (locale "C") (timezone "Europe/Paris")
+                        (issue "Hello!\n")
+                        (skeletons '())
+                        (pam-services '())
+                        (profile "/run/current-system/profile")
+                        (sudoers ""))
+  "Return a derivation that builds the static part of the /etc directory."
+  (mlet* %store-monad
+      ((pam.d      (pam-services->directory pam-services))
+       (sudoers    (text-file "sudoers" sudoers))
+       (login.defs (text-file "login.defs" "# Empty for now.\n"))
+       (shells     (text-file "shells"            ; used by xterm and others
+                              "\
+/bin/sh
+/run/current-system/profile/bin/sh
+/run/current-system/profile/bin/bash\n"))
+       (issue      (text-file "issue" issue))
+
+       ;; TODO: Generate bashrc from packages' search-paths.
+       (bashrc    (text-file* "bashrc"  "
+export PS1='\\u@\\h\\$ '
+
+export LC_ALL=\"" locale "\"
+export TZ=\"" timezone "\"
+export TZDIR=\"" tzdata "/share/zoneinfo\"
+
+# Tell 'modprobe' & co. where to look for modules.
+export LINUX_MODULE_DIRECTORY=/run/booted-system/kernel/lib/modules
+
+export PATH=$HOME/.guix-profile/bin:/run/current-system/profile/bin
+export PATH=/run/setuid-programs:/run/current-system/profile/sbin:$PATH
+export CPATH=$HOME/.guix-profile/include:" profile "/include
+export LIBRARY_PATH=$HOME/.guix-profile/lib:" profile "/lib
+alias ls='ls -p --color'
+alias ll='ls -l'
+"))
+       (skel      (skeleton-directory skeletons)))
+    (file-union "etc"
+                `(("services" ,#~(string-append #$net-base "/etc/services"))
+                  ("protocols" ,#~(string-append #$net-base "/etc/protocols"))
+                  ("rpc" ,#~(string-append #$net-base "/etc/rpc"))
+                  ("pam.d" ,#~#$pam.d)
+                  ("login.defs" ,#~#$login.defs)
+                  ("issue" ,#~#$issue)
+                  ("skel" ,#~#$skel)
+                  ("shells" ,#~#$shells)
+                  ("profile" ,#~#$bashrc)
+                  ("localtime" ,#~(string-append #$tzdata "/share/zoneinfo/"
+                                                 #$timezone))
+                  ("sudoers" ,#~#$sudoers)))))
+
+(define (operating-system-profile os)
+  "Return a derivation that builds the system profile of OS."
+  (profile-derivation (manifest (map package->manifest-entry
+                                     (operating-system-packages 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."
+  (define users
+    ;; 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))))
+
+  (mlet %store-monad ((services (operating-system-services os)))
+    (return (append users
+                    (append-map service-user-accounts services)))))
+
+(define (operating-system-etc-directory os)
+  "Return that static part of the /etc directory of OS."
+  (mlet* %store-monad
+      ((services     (operating-system-services os))
+       (pam-services ->
+                     ;; Services known to PAM.
+                     (delete-duplicates
+                      (append (operating-system-pam-services os)
+                              (append-map service-pam-services services))))
+       (profile-drv (operating-system-profile os))
+       (skeletons   (operating-system-skeletons os)))
+   (etc-directory #:pam-services pam-services
+                  #:skeletons skeletons
+                  #:issue (operating-system-issue os)
+                  #:locale (operating-system-locale os)
+                  #:timezone (operating-system-timezone os)
+                  #:sudoers (operating-system-sudoers os)
+                  #:profile profile-drv)))
+
+(define %setuid-programs
+  ;; Default set of setuid-root programs.
+  (let ((shadow (@ (gnu packages admin) shadow)))
+    (list #~(string-append #$shadow "/bin/passwd")
+          #~(string-append #$shadow "/bin/su")
+          #~(string-append #$inetutils "/bin/ping")
+          #~(string-append #$sudo "/bin/sudo")
+          #~(string-append #$fuse "/bin/fusermount"))))
+
+(define %sudoers-specification
+  ;; Default /etc/sudoers contents: 'root' and all members of the 'wheel'
+  ;; group can do anything.  See
+  ;; <http://www.sudo.ws/sudo/man/1.8.10/sudoers.man.html>.
+  ;; TODO: Add a declarative API.
+  "root ALL=(ALL) ALL
+%wheel ALL=(ALL) ALL\n")
+
+(define (user-group->gexp group)
+  "Turn GROUP, a <user-group> object, into a list-valued gexp suitable for
+'active-groups'."
+  #~(list #$(user-group-name group)
+          #$(user-group-password group)
+          #$(user-group-id group)
+          #$(user-group-system? group)))
+
+(define (user-account->gexp account)
+  "Turn ACCOUNT, a <user-account> object, into a list-valued gexp suitable for
+'activate-users'."
+  #~`(#$(user-account-name account)
+      #$(user-account-uid account)
+      #$(user-account-group account)
+      #$(user-account-supplementary-groups account)
+      #$(user-account-comment account)
+      #$(user-account-home-directory account)
+      ,#$(user-account-shell account)             ; this one is a gexp
+      #$(user-account-password account)
+      #$(user-account-system? account)))
+
+(define (operating-system-activation-script os)
+  "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."
+  (define %modules
+    '((guix build activation)
+      (guix build utils)
+      (guix build linux-initrd)))
+
+  (define (service-activations services)
+    ;; Return the activation scripts for SERVICES.
+    (let ((gexps (filter-map service-activate services)))
+      (sequence %store-monad (map (cut gexp->file "activate-service.scm" <>)
+                                  gexps))))
+
+  (mlet* %store-monad ((services (operating-system-services os))
+                       (actions  (service-activations services))
+                       (etc      (operating-system-etc-directory os))
+                       (modules  (imported-modules %modules))
+                       (compiled (compiled-modules %modules))
+                       (accounts (operating-system-accounts os)))
+    (define setuid-progs
+      (operating-system-setuid-programs os))
+
+    (define user-specs
+      (map user-account->gexp accounts))
+
+    (define groups
+      (append (operating-system-groups os)
+              (append-map service-user-groups services)))
+
+    (define group-specs
+      (map user-group->gexp groups))
+
+    (gexp->file "activate"
+                #~(begin
+                    (eval-when (expand load eval)
+                      ;; Make sure 'use-modules' below succeeds.
+                      (set! %load-path (cons #$modules %load-path))
+                      (set! %load-compiled-path
+                            (cons #$compiled %load-compiled-path)))
+
+                    (use-modules (guix build activation))
+
+                    ;; Populate /etc.
+                    (activate-etc #$etc)
+
+                    ;; Add users and user groups.
+                    (setenv "PATH"
+                            (string-append #$(@ (gnu packages admin) shadow)
+                                           "/sbin"))
+                    (activate-users+groups (list #$@user-specs)
+                                           (list #$@group-specs))
+
+                    ;; Activate setuid programs.
+                    (activate-setuid-programs (list #$@setuid-progs))
+
+                    ;; Run the services' activation snippets.
+                    ;; TODO: Use 'load-compiled'.
+                    (for-each primitive-load '#$actions)
+
+                    ;; Set up /run/current-system.
+                    (activate-current-system)))))
+
+(define (operating-system-boot-script os)
+  "Return the boot script for OS---i.e., the code started by the initrd once
+we're running in the final root."
+  (mlet* %store-monad ((services (operating-system-services os))
+                       (activate (operating-system-activation-script os))
+                       (dmd-conf (dmd-configuration-file services)))
+    (gexp->file "boot"
+                #~(begin
+                    ;; Activate the system.
+                    ;; TODO: Use 'load-compiled'.
+                    (primitive-load #$activate)
+
+                    ;; Keep track of the booted system.
+                    (false-if-exception (delete-file "/run/booted-system"))
+                    (symlink (readlink "/run/current-system")
+                             "/run/booted-system")
+
+                    ;; Close any remaining open file descriptors to be on the
+                    ;; safe side.  This must be the very last thing we do,
+                    ;; because Guile has internal FDs such as 'sleep_pipe'
+                    ;; that need to be alive.
+                    (let loop ((fd 3))
+                      (when (< fd 1024)
+                        (false-if-exception (close-fdes fd))
+                        (loop (+ 1 fd))))
+
+                    ;; Start dmd.
+                    (execl (string-append #$dmd "/bin/dmd")
+                           "dmd" "--config" #$dmd-conf)))))
+
+(define (operating-system-root-file-system os)
+  "Return the root file system of OS."
+  (find (match-lambda
+         (($ <file-system> _ _ "/") #t)
+         (_ #f))
+        (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 (match-lambda
+             (($ <file-system> device title "/")
+              #t)
+             (($ <file-system> device title mount-point type flags
+                               options boot?)
+              boot?))
+            (operating-system-file-systems os)))
+
+  (mlet %store-monad
+      ((initrd ((operating-system-initrd os) boot-file-systems)))
+    (return #~(string-append #$initrd "/initrd"))))
+
+(define (kernel->grub-label kernel)
+  "Return a label for the GRUB menu entry that boots KERNEL."
+  (string-append "GNU system with "
+                 (string-titlecase (package-name kernel)) " "
+                 (package-version kernel)
+                 " (technology preview)"))
+
+(define* (operating-system-grub.cfg os #:optional (old-entries '()))
+  "Return the GRUB configuration file for OS.  Use OLD-ENTRIES to populate the
+\"old entries\" menu."
+  (mlet* %store-monad
+      ((system      (operating-system-derivation os))
+       (root-fs ->  (operating-system-root-file-system os))
+       (kernel ->   (operating-system-kernel os))
+       (entries ->  (list (menu-entry
+                           (label (kernel->grub-label kernel))
+                           (linux kernel)
+                           (linux-arguments
+                            (list (string-append "--root="
+                                                 (file-system-device root-fs))
+                                  #~(string-append "--system=" #$system)
+                                  #~(string-append "--load=" #$system
+                                                   "/boot")))
+                           (initrd #~(string-append #$system "/initrd"))))))
+    (grub-configuration-file (operating-system-bootloader os) entries
+                             #:old-entries old-entries)))
+
+(define (operating-system-parameters-file os)
+  "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."
+  (mlet %store-monad ((initrd   (operating-system-initrd-file os))
+                      (root ->  (operating-system-root-file-system os))
+                      (label -> (kernel->grub-label
+                                 (operating-system-kernel os))))
+    (gexp->file "parameters"
+                #~(boot-parameters (version 0)
+                                   (label #$label)
+                                   (root-device #$(file-system-device root))
+                                   (kernel #$(operating-system-kernel os))
+                                   (initrd #$initrd)))))
+
+(define (operating-system-derivation os)
+  "Return a derivation that builds OS."
+  (mlet* %store-monad
+      ((profile     (operating-system-profile os))
+       (etc         (operating-system-etc-directory os))
+       (boot        (operating-system-boot-script os))
+       (kernel  ->  (operating-system-kernel os))
+       (initrd      (operating-system-initrd-file os))
+       (params      (operating-system-parameters-file os)))
+    (file-union "system"
+                `(("boot" ,#~#$boot)
+                  ("kernel" ,#~#$kernel)
+                  ("parameters" ,#~#$params)
+                  ("initrd" ,initrd)
+                  ("profile" ,#~#$profile)
+                  ("etc" ,#~#$etc)))))
+
+;;; system.scm ends here