guix/guix/scripts/system.scm

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Alex Kost <alezost@gmail.com>
;;; Copyright © 2016, 2017 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 (guix scripts system)
  #:use-module (guix config)
  #:use-module (guix ui)
  #:use-module (guix store)
  #:use-module (guix grafts)
  #:use-module (guix gexp)
  #:use-module (guix derivations)
  #:use-module (guix packages)
  #:use-module (guix utils)
  #:use-module (guix monads)
  #:use-module (guix records)
  #:use-module (guix profiles)
  #:use-module (guix scripts)
  #:use-module (guix scripts build)
  #:use-module (guix graph)
  #:use-module (guix scripts graph)
  #:use-module (guix build utils)
  #:use-module (gnu build install)
  #:use-module (gnu system)
  #:use-module (gnu bootloader)
  #:use-module (gnu system file-systems)
  #:use-module (gnu system linux-container)
  #:use-module (gnu system vm)
  #:use-module (gnu services)
  #:use-module (gnu services shepherd)
  #:use-module (gnu services herd)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (srfi srfi-37)
  #:use-module (ice-9 match)
  #:use-module (rnrs bytevectors)
  #:export (guix-system
            read-operating-system))


;;;
;;; Operating system declaration.
;;;

(define %user-module
  ;; Module in which the machine description file is loaded.
  (make-user-module '((gnu system)
                      (gnu services)
                      (gnu system shadow))))

(define (read-operating-system file)
  "Read the operating-system declaration from FILE and return it."
  (load* file %user-module))



;;;
;;; Installation.
;;;

(define-syntax-rule (save-load-path-excursion body ...)
  "Save the current values of '%load-path' and '%load-compiled-path', run
BODY..., and restore them."
  (let ((path %load-path)
        (cpath %load-compiled-path))
    (dynamic-wind
      (const #t)
      (lambda ()
        body ...)
      (lambda ()
        (set! %load-path path)
        (set! %load-compiled-path cpath)))))

(define-syntax-rule (save-environment-excursion body ...)
  "Save the current environment variables, run BODY..., and restore them."
  (let ((env (environ)))
    (dynamic-wind
      (const #t)
      (lambda ()
        body ...)
      (lambda ()
        (environ env)))))

(define topologically-sorted*
  (store-lift topologically-sorted))


(define* (copy-item item target
                    #:key (log-port (current-error-port)))
  "Copy ITEM to the store under root directory TARGET and register it."
  (mlet* %store-monad ((refs (references* item)))
    (let ((dest  (string-append target item))
          (state (string-append target "/var/guix")))
      (format log-port "copying '~a'...~%" item)

      ;; Remove DEST if it exists to make sure that (1) we do not fail badly
      ;; while trying to overwrite it (see <http://bugs.gnu.org/20722>), and
      ;; (2) we end up with the right contents.
      (when (file-exists? dest)
        (delete-file-recursively dest))

      (copy-recursively item dest
                        #:log (%make-void-port "w"))

      ;; Register ITEM; as a side-effect, it resets timestamps, etc.
      ;; Explicitly use "TARGET/var/guix" as the state directory, to avoid
      ;; reproducing the user's current settings; see
      ;; <http://bugs.gnu.org/18049>.
      (unless (register-path item
                             #:prefix target
                             #:state-directory state
                             #:references refs)
        (leave (G_ "failed to register '~a' under '~a'~%")
               item target))

      (return #t))))

(define* (copy-closure item target
                       #:key (log-port (current-error-port)))
  "Copy ITEM and all its dependencies to the store under root directory
TARGET, and register them."
  (mlet* %store-monad ((refs    (references* item))
                       (to-copy (topologically-sorted*
                                 (delete-duplicates (cons item refs)
                                                    string=?))))
    (sequence %store-monad
              (map (cut copy-item <> target #:log-port log-port)
                   to-copy))))

(define* (install-bootloader installer-drv
                             #:key
                             bootcfg bootcfg-file
                             device target)
  "Call INSTALLER-DRV with error handling, in %STORE-MONAD."
  (with-monad %store-monad
    (let* ((gc-root      (string-append target %gc-roots-directory
                                        "/bootcfg"))
           (temp-gc-root (string-append gc-root ".new"))
           (install (and installer-drv
                         (derivation->output-path installer-drv)))
           (bootcfg (derivation->output-path bootcfg)))
      ;; Prepare the symlink to bootloader config file to make sure that it's
      ;; a GC root when 'installer-drv' completes (being a bit paranoid.)
      (switch-symlinks temp-gc-root bootcfg)

      (unless (false-if-exception
               (begin
                 (install-boot-config bootcfg bootcfg-file target)
                 (when install
                   (save-load-path-excursion (primitive-load install)))))
        (delete-file temp-gc-root)
        (leave (G_ "failed to install bootloader on device ~a '~a'~%") install device))

      ;; Register bootloader config file as a GC root so that its dependencies
      ;; (background image, font, etc.) are not reclaimed.
      (rename-file temp-gc-root gc-root)
      (return #t))))

(define* (install os-drv target
                  #:key (log-port (current-output-port))
                  bootloader-installer install-bootloader?
                  bootcfg bootcfg-file
                  device)
  "Copy the closure of BOOTCFG, which includes the output of OS-DRV, to
directory TARGET.  TARGET must be an absolute directory name since that's what
'guix-register' expects.

When INSTALL-BOOTLOADER? is true, install bootloader on DEVICE, using BOOTCFG."
  (define (maybe-copy to-copy)
    (with-monad %store-monad
      (if (string=? target "/")
          (begin
            (warning (G_ "initializing the current root file system~%"))
            (return #t))
          (begin
            ;; Make sure the target store exists.
            (mkdir-p (string-append target (%store-prefix)))

            ;; Copy items to the new store.
            (copy-closure to-copy target #:log-port log-port)))))

  ;; Make sure TARGET is root-owned when running as root, but still allow
  ;; non-root uses (useful for testing.)  See
  ;; <http://lists.gnu.org/archive/html/guix-devel/2015-05/msg00452.html>.
  (if (zero? (geteuid))
      (chown target 0 0)
      (warning (G_ "not running as 'root', so \
the ownership of '~a' may be incorrect!~%")
               target))

  (chmod target #o755)
  (let ((os-dir   (derivation->output-path os-drv))
        (format   (lift format %store-monad))
        (populate (lift2 populate-root-file-system %store-monad)))

    (mbegin %store-monad
      ;; Copy the closure of BOOTCFG, which includes OS-DIR,
      ;; eventual background image and so on.
      (maybe-copy
       (derivation->output-path bootcfg))

      ;; Create a bunch of additional files.
      (format log-port "populating '~a'...~%" target)
      (populate os-dir target)

      (mwhen install-bootloader?
        (install-bootloader bootloader-installer
                            #:bootcfg bootcfg
                            #:bootcfg-file bootcfg-file
                            #:device device
                            #:target target)))))


;;;
;;; Reconfiguration.
;;;

(define %system-profile
  ;; The system profile.
  (string-append %state-directory "/profiles/system"))

(define-syntax-rule (with-shepherd-error-handling mbody ...)
  "Catch and report Shepherd errors that arise when binding MBODY, a monadic
expression in %STORE-MONAD."
  (lambda (store)
    (catch 'system-error
      (lambda ()
        (guard (c ((shepherd-error? c)
                   (values (report-shepherd-error c) store)))
          (values (run-with-store store (begin mbody ...))
                  store)))
      (lambda (key proc format-string format-args errno . rest)
        (warning (G_ "while talking to shepherd: ~a~%")
                 (apply format #f format-string format-args))
        (values #f store)))))

(define (report-shepherd-error error)
  "Report ERROR, a '&shepherd-error' error condition object."
  (cond ((service-not-found-error? error)
         (report-error (G_ "service '~a' could not be found~%")
                       (service-not-found-error-service error)))
        ((action-not-found-error? error)
         (report-error (G_ "service '~a' does not have an action '~a'~%")
                       (action-not-found-error-service error)
                       (action-not-found-error-action error)))
        ((action-exception-error? error)
         (report-error (G_ "exception caught while executing '~a' \
on service '~a':~%")
                       (action-exception-error-action error)
                       (action-exception-error-service error))
         (print-exception (current-error-port) #f
                          (action-exception-error-key error)
                          (action-exception-error-arguments error)))
        ((unknown-shepherd-error? error)
         (report-error (G_ "something went wrong: ~s~%")
                       (unknown-shepherd-error-sexp error)))
        ((shepherd-error? error)
         (report-error (G_ "shepherd error~%")))
        ((not error)                              ;not an error
         #t)))

(define (call-with-service-upgrade-info new-services mproc)
  "Call MPROC, a monadic procedure in %STORE-MONAD, passing it the list of
names of services to load (upgrade), and the list of names of services to
unload."
  (match (current-services)
    ((services ...)
     (let-values (((to-unload to-load)
                   (shepherd-service-upgrade services new-services)))
       (mproc to-load
              (map (compose first live-service-provision)
                   to-unload))))
    (#f
     (with-monad %store-monad
       (warning (G_ "failed to obtain list of shepherd services~%"))
       (return #f)))))

(define (upgrade-shepherd-services os)
  "Upgrade the Shepherd (PID 1) by unloading obsolete services and loading new
services specified in OS and not currently running.

This is currently very conservative in that it does not stop or unload any
running service.  Unloading or stopping the wrong service ('udev', say) could
bring the system down."
  (define new-services
    (service-value
     (fold-services (operating-system-services os)
                    #:target-type shepherd-root-service-type)))

  ;; Arrange to simply emit a warning if the service upgrade fails.
  (with-shepherd-error-handling
   (call-with-service-upgrade-info new-services
     (lambda (to-load to-unload)
        (for-each (lambda (unload)
                    (info (G_ "unloading service '~a'...~%") unload)
                    (unload-service unload))
                  to-unload)

        (with-monad %store-monad
          (munless (null? to-load)
            (let ((to-load-names  (map shepherd-service-canonical-name to-load))
                  (to-start       (filter shepherd-service-auto-start? to-load)))
              (info (G_ "loading new services:~{ ~a~}...~%") to-load-names)
              (mlet %store-monad ((files (mapm %store-monad shepherd-service-file
                                               to-load)))
                ;; Here we assume that FILES are exactly those that were computed
                ;; as part of the derivation that built OS, which is normally the
                ;; case.
                (load-services (map derivation->output-path files))

                (for-each start-service
                          (map shepherd-service-canonical-name to-start))
                (return #t)))))))))

(define* (switch-to-system os
                           #:optional (profile %system-profile))
  "Make a new generation of PROFILE pointing to the directory of OS, switch to
it atomically, and then run OS's activation script."
  (mlet* %store-monad ((drv    (operating-system-derivation os))
                       (script (operating-system-activation-script os)))
    (let* ((system     (derivation->output-path drv))
           (number     (+ 1 (generation-number profile)))
           (generation (generation-file-name profile number)))
      (switch-symlinks generation system)
      (switch-symlinks profile generation)

      (format #t (G_ "activating system...~%"))

      ;; The activation script may change $PATH, among others, so protect
      ;; against that.
      (save-environment-excursion
       ;; Tell 'activate-current-system' what the new system is.
       (setenv "GUIX_NEW_SYSTEM" system)

       ;; The activation script may modify '%load-path' & co., so protect
       ;; against that.  This is necessary to ensure that
       ;; 'upgrade-shepherd-services' gets to see the right modules when it
       ;; computes derivations with 'gexp->derivation'.
       (save-load-path-excursion
        (primitive-load (derivation->output-path script))))

      ;; Finally, try to update system services.
      (upgrade-shepherd-services os))))

(define-syntax-rule (unless-file-not-found exp)
  (catch 'system-error
    (lambda ()
      exp)
    (lambda args
      (if (= ENOENT (system-error-errno args))
          #f
          (apply throw args)))))

(define (seconds->string seconds)
  "Return a string representing the date for SECONDS."
  (let ((time (make-time time-utc 0 seconds)))
    (date->string (time-utc->date time)
                  "~Y-~m-~d ~H:~M")))

(define* (profile-boot-parameters #:optional (profile %system-profile)
                                  (numbers (generation-numbers profile)))
  "Return a list of 'boot-parameters' for the generations of PROFILE specified by
NUMBERS, which is a list of generation numbers."
  (define (system->boot-parameters system number time)
    (unless-file-not-found
     (let* ((params           (read-boot-parameters-file system))
            (label            (boot-parameters-label params)))
       (boot-parameters
         (inherit params)
         (label (string-append label " (#"
                               (number->string number) ", "
                               (seconds->string time) ")"))))))
  (let* ((systems (map (cut generation-file-name profile <>)
                       numbers))
         (times   (map (lambda (system)
                         (unless-file-not-found
                          (stat:mtime (lstat system))))
                       systems)))
    (filter-map system->boot-parameters systems numbers times)))


;;;
;;; Roll-back.
;;;
(define (roll-back-system store)
  "Roll back the system profile to its previous generation.  STORE is an open
connection to the store."
  (switch-to-system-generation store "-1"))

;;;
;;; Switch generations.
;;;
(define (switch-to-system-generation store spec)
  "Switch the system profile to the generation specified by SPEC, and
re-install bootloader with a configuration file that uses the specified system
generation as its default entry.  STORE is an open connection to the store."
  (let ((number (relative-generation-spec->number %system-profile spec)))
    (if number
        (begin
          (reinstall-bootloader store number)
          (switch-to-generation* %system-profile number))
        (leave (G_ "cannot switch to system generation '~a'~%") spec))))

(define* (system-bootloader-name #:optional (system %system-profile))
  "Return the bootloader name stored in SYSTEM's \"parameters\" file."
  (let ((params (unless-file-not-found
                 (read-boot-parameters-file system))))
    (boot-parameters-bootloader-name params)))

(define (reinstall-bootloader store number)
  "Re-install bootloader for existing system profile generation NUMBER.
STORE is an open connection to the store."
  (let* ((generation (generation-file-name %system-profile number))
         (params (unless-file-not-found
                  (read-boot-parameters-file generation)))
         ;; Detect the bootloader used in %system-profile.
         (bootloader (lookup-bootloader-by-name (system-bootloader-name)))

         ;; Use the detected bootloader with default configuration.
         ;; It will be enough to allow the system to boot.
         (bootloader-config (bootloader-configuration
                             (bootloader bootloader)))

         ;; Make the specified system generation the default entry.
         (entries (profile-boot-parameters %system-profile (list number)))
         (old-generations (delv number (generation-numbers %system-profile)))
         (old-entries (profile-boot-parameters
                       %system-profile old-generations)))
    (run-with-store store
      (mlet* %store-monad
          ((bootcfg ((bootloader-configuration-file-generator bootloader)
                     bootloader-config entries
                     #:old-entries old-entries))
           (bootcfg-file -> (bootloader-configuration-file bootloader))
           (target -> "/")
           (drvs -> (list bootcfg)))
        (mbegin %store-monad
          (show-what-to-build* drvs)
          (built-derivations drvs)
          ;; Only install bootloader configuration file. Thus, no installer
          ;; nor device is provided here.
          (install-bootloader #f
                              #:bootcfg bootcfg
                              #:bootcfg-file bootcfg-file
                              #:device #f
                              #:target target))))))


;;;
;;; Graphs.
;;;

(define (service-node-label service)
  "Return a label to represent SERVICE."
  (let ((type  (service-kind service))
        (value (service-value service)))
    (string-append (symbol->string (service-type-name type))
                   (cond ((or (number? value) (symbol? value))
                          (string-append " " (object->string value)))
                         ((string? value)
                          (string-append " " value))
                         ((file-system? value)
                          (string-append " " (file-system-mount-point value)))
                         (else
                          "")))))

(define (service-node-type services)
  "Return a node type for SERVICES.  Since <service> instances are not
self-contained (they express dependencies on service types, not on services),
we have to create the 'edges' procedure dynamically as a function of the full
list of services."
  (node-type
   (name "service")
   (description "the DAG of services")
   (identifier (lift1 object-address %store-monad))
   (label service-node-label)
   (edges (lift1 (service-back-edges services) %store-monad))))

(define (shepherd-service-node-label service)
  "Return a label for a node representing a <shepherd-service>."
  (string-join (map symbol->string (shepherd-service-provision service))))

(define (shepherd-service-node-type services)
  "Return a node type for SERVICES, a list of <shepherd-service>."
  (node-type
   (name "shepherd-service")
   (description "the dependency graph of shepherd services")
   (identifier (lift1 shepherd-service-node-label %store-monad))
   (label shepherd-service-node-label)
   (edges (lift1 (shepherd-service-back-edges services) %store-monad))))


;;;
;;; Generations.
;;;

(define* (display-system-generation number
                                    #:optional (profile %system-profile))
  "Display a summary of system generation NUMBER in a human-readable format."
  (unless (zero? number)
    (let* ((generation  (generation-file-name profile number))
           (params      (read-boot-parameters-file generation))
           (label       (boot-parameters-label params))
           (bootloader-name (boot-parameters-bootloader-name params))
           (root        (boot-parameters-root-device params))
           (root-device (if (bytevector? root)
                            (uuid->string root)
                            root))
           (kernel      (boot-parameters-kernel params)))
      (display-generation profile number)
      (format #t (G_ "  file name: ~a~%") generation)
      (format #t (G_ "  canonical file name: ~a~%") (readlink* generation))
      ;; TRANSLATORS: Please preserve the two-space indentation.
      (format #t (G_ "  label: ~a~%") label)
      (format #t (G_ "  bootloader: ~a~%") bootloader-name)
      (format #t (G_ "  root device: ~a~%") root-device)
      (format #t (G_ "  kernel: ~a~%") kernel))))

(define* (list-generations pattern #:optional (profile %system-profile))
  "Display in a human-readable format all the system generations matching
PATTERN, a string.  When PATTERN is #f, display all the system generations."
  (cond ((not (file-exists? profile))             ; XXX: race condition
         (raise (condition (&profile-not-found-error
                            (profile profile)))))
        ((string-null? pattern)
         (for-each display-system-generation (profile-generations profile)))
        ((matching-generations pattern profile)
         =>
         (lambda (numbers)
           (if (null-list? numbers)
               (exit 1)
               (leave-on-EPIPE
                (for-each display-system-generation numbers)))))
        (else
         (leave (G_ "invalid syntax: ~a~%") pattern))))


;;;
;;; Action.
;;;

(define* (system-derivation-for-action os action
                                       #:key image-size file-system-type
                                       full-boot? mappings)
  "Return as a monadic value the derivation for OS according to ACTION."
  (case action
    ((build init reconfigure)
     (operating-system-derivation os))
    ((container)
     (container-script os #:mappings mappings))
    ((vm-image)
     (system-qemu-image os #:disk-image-size image-size))
    ((vm)
     (system-qemu-image/shared-store-script os
                                            #:full-boot? full-boot?
                                            #:disk-image-size
                                            (if full-boot?
                                                image-size
                                                (* 70 (expt 2 20)))
                                            #:mappings mappings))
    ((disk-image)
     (system-disk-image os
                        #:name (match file-system-type
                                 ("iso9660" "image.iso")
                                 (_         "disk-image"))
                        #:disk-image-size image-size
                        #:file-system-type file-system-type))))

(define (maybe-suggest-running-guix-pull)
  "Suggest running 'guix pull' if this has never been done before."
  ;; The reason for this is that the 'guix' binding that we see here comes
  ;; from either ~/.config/latest or, if it's missing, from the
  ;; globally-installed Guix, which is necessarily older.  See
  ;; <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html> for
  ;; a discussion.
  (define latest
    (string-append (config-directory) "/latest"))

  (unless (file-exists? latest)
    (warning (G_ "~a not found: 'guix pull' was never run~%") latest)
    (warning (G_ "Consider running 'guix pull' before 'reconfigure'.~%"))
    (warning (G_ "Failing to do that may downgrade your system!~%"))))

(define (bootloader-installer-derivation installer
                                         bootloader device target)
  "Return a file calling INSTALLER gexp with given BOOTLOADER, DEVICE
and TARGET arguments."
  (with-monad %store-monad