aboutsummaryrefslogtreecommitdiff
path: root/guix/scripts/system.scm
blob: 766cab1aad5de6fa1e0bff1a1d25fbf22b7bdd10 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Alex Kost <alezost@gmail.com>
;;; Copyright © 2016, 2017, 2018 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 (guix progress)
  #:use-module ((guix build syscalls) #:select (terminal-columns))
  #:use-module (gnu build install)
  #:autoload   (gnu build file-systems)
                 (find-partition-by-label find-partition-by-uuid)
  #:autoload   (gnu build linux-modules)
                 (device-module-aliases matching-modules)
  #:use-module (gnu system linux-initrd)
  #:use-module (gnu system)
  #:use-module (gnu bootloader)
  #:use-module (gnu system file-systems)
  #:use-module (gnu system mapped-devices)
  #:use-module (gnu system linux-container)
  #:use-module (gnu system uuid)
  #: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 references target
                    #:key (log-port (current-error-port)))
  "Copy ITEM to the store under root directory TARGET and register it with
REFERENCES as its set of references."
  (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 references)
      (leave (G_ "failed to register '~a' under '~a'~%")
             item target))))

(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 ((to-copy (topologically-sorted* (list item)))
                       (refs    (mapm %store-monad references* to-copy)))
    (define progress-bar
      (progress-reporter/bar (length to-copy)
                             (format #f (G_ "copying to '~a'...")
                                     target)))

    (call-with-progress-reporter progress-bar
      (lambda (report)
        (let ((void (%make-void-port "w")))
          (for-each (lambda (item refs)
                      (copy-item item refs target #:log-port void)
                      (report))
                    to-copy refs))))

    (return *unspecified*)))

(define* (install-bootloader installer-drv
                             #:key
                             bootcfg bootcfg-file
                             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 ~a~%") install))

      ;; 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)
  "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 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
                            #: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
                                               (compose lower-object
                                                        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
                                   (reverse (generation-numbers profile))))
  "Return a list of 'boot-parameters' for the generations of PROFILE specified
by NUMBERS, which is a list of generation numbers. The list is ordered from
the most recent to the oldest profiles."
  (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))
         ;; 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.
         (params (profile-boot-parameters %system-profile (list number)))
         (old-generations (delv number (generation-numbers %system-profile)))
         (old-params (profile-boot-parameters
                       %system-profile old-generations))
         (entries (map boot-parameters->menu-entry params))
         (old-entries (map boot-parameters->menu-entry old-params)))
    (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 is
          ;; provided here.
          (install-bootloader #f
                              #:bootcfg bootcfg
                              #:bootcfg-file bootcfg-file
                              #: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~%")
              (if (uuid? root-device)
                  (uuid->string root-device)
                  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))))


;;;
;;; File system declaration checks.
;;;

(define (check-file-system-availability file-systems)
  "Check whether the UUIDs or partition labels that FILE-SYSTEMS refer to, if
any, are available.  Raise an error if they're not."
  (define relevant
    (filter (lambda (fs)
              (and (file-system-mount? fs)
                   (not (member (file-system-type fs)
                                %pseudo-file-system-types))
                   (not (memq 'bind-mount (file-system-flags fs)))))
            file-systems))

  (define labeled
    (filter (lambda (fs)
              (file-system-label? (file-system-device fs)))
            relevant))

  (define literal
    (filter (lambda (fs)
              (string? (file-system-device fs)))
            relevant))

  (define uuid
    (filter (lambda (fs)
              (uuid? (file-system-device fs)))
            relevant))

  (define fail? #f)

  (define (file-system-location* fs)
    (location->string
     (source-properties->location
      (file-system-location fs))))

  (let-syntax ((error (syntax-rules ()
                        ((_ args ...)
                         (begin
                           (set! fail? #t)
                           (format (current-error-port)
                                   args ...))))))
    (for-each (lambda (fs)
                (catch 'system-error
                  (lambda ()
                    (stat (file-system-device fs)))
                  (lambda args
                    (let ((errno  (system-error-errno args))
                          (device (file-system-device fs)))
                      (error (G_ "~a: error: device '~a' not found: ~a~%")
                             (file-system-location* fs) device
                             (strerror errno))
                      (unless (string-prefix? "/" device)
                        (display-hint (format #f (G_ "If '~a' is a file system
label, write @code{(file-system-label ~s)} in your @code{device} field.")
                                              device device)))))))
              literal)
    (for-each (lambda (fs)
                (let ((label (file-system-label->string
                              (file-system-device fs))))
                  (unless (find-partition-by-label label)
                    (error (G_ "~a: error: file system with label '~a' not found~%")
                           (file-system-location* fs) label))))
              labeled)
    (for-each (lambda (fs)
                (unless (find-partition-by-uuid (file-system-device fs))
                  (error (G_ "~a: error: file system with UUID '~a' not found~%")
                         (file-system-location* fs)
                         (uuid->string (file-system-device fs)))))
              uuid)

    (when fail?
      ;; Better be safe than sorry.
      (exit 1))))

(define (check-mapped-devices os)
  "Check that each of MAPPED-DEVICES is valid according to the 'check'
procedure of its type."
  (define boot-mapped-devices
    (operating-system-boot-mapped-devices os))

  (define (needed-for-boot? md)
    (memq md boot-mapped-devices))

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

  (for-each (lambda (md)
              (let ((check (mapped-device-kind-check
                            (mapped-device-type md))))
                ;; We expect CHECK to raise an exception with a detailed
                ;; '&message' if something goes wrong.
                (check md
                       #:needed-for-boot? (needed-for-boot? md)
                       #:initrd-modules initrd-modules)))
            (operating-system-mapped-devices os)))

(define (check-initrd-modules os)
  "Check that modules needed by 'needed-for-boot' file systems in OS are
available in the initrd.  Note that mapped devices are responsible for
checking this by themselves in their 'check' procedure."
  (define (file-system-/dev fs)
    (let ((device (file-system-device fs)))
      (match device
        ((? string?)
         device)
        ((? uuid?)
         (find-partition-by-uuid device))
        ((? file-system-label?)
         (find-partition-by-label (file-system-label->string device))))))

  (define file-systems
    (filter file-system-needed-for-boot?
            (operating-system-file-systems os)))

  (for-each (lambda (fs)
              (check-device-initrd-modules (file-system-/dev fs)
                                           (operating-system-initrd-modules os)
                                           (source-properties->location
                                            (file-system-location fs))))
            file-systems))


;;;
;;; 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))
    ((docker-image)
     (system-docker-image os #:register-closures? #t))))

(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
    (gexp->file "bootloader-installer"
                (with-imported-modules '((gnu build bootloader)
                                         (guix build utils))
                  #~(begin
                      (use-modules (gnu build bootloader)
                                   (guix build utils)
                                   (ice-9 binary-ports))
                      (#$installer #$bootloader #$device #$target))))))

(define* (perform-action action os
                         #:key skip-safety-checks?
                         install-bootloader?
                         dry-run? derivations-only?
                         use-substitutes? bootloader-target target
                         image-size file-system-type full-boot?
                         (mappings '())
                         (gc-root #f))
  "Perform ACTION for OS.  INSTALL-BOOTLOADER? specifies whether to install
bootloader; BOOTLOADER-TAGET is the target for the bootloader; TARGET is the
target root directory; IMAGE-SIZE is the size of the image to be built, for
the 'vm-image' and 'disk-image' actions.  The root file system is created as a
FILE-SYSTEM-TYPE file system.  FULL-BOOT? is used for the 'vm' action; it
determines whether to boot directly to the kernel or to the bootloader.

When DERIVATIONS-ONLY? is true, print the derivation file name(s) without
building anything.

When GC-ROOT is a path, also make that path an indirect root of the build
output when building a system derivation, such as a disk image.

When SKIP-SAFETY-CHECKS? is true, skip the file system and initrd module
static checks."
  (define println
    (cut format #t "~a~%" <>))

  (when (eq? action 'reconfigure)
    (maybe-suggest-running-guix-pull))

  ;; Check whether the declared file systems exist.  This is better than
  ;; instantiating a broken configuration.  Assume that we can only check if
  ;; running as root.
  (when (and (not skip-safety-checks?)
             (memq action '(init reconfigure)))
    (check-mapped-devices os)
    (when (zero? (getuid))
      (check-file-system-availability (operating-system-file-systems os))
      (check-initrd-modules os)))

  (mlet* %store-monad
      ((sys       (system-derivation-for-action os action
                                                #:file-system-type file-system-type
                                                #:image-size image-size
                                                #:full-boot? full-boot?
                                                #:mappings mappings))
       (bootloader -> (bootloader-configuration-bootloader
                       (operating-system-bootloader os)))
       (bootloader-package
        (let ((package (bootloader-package bootloader)))
          (if package
              (package->derivation package)
              (return #f))))
       (bootcfg  (if (eq? 'container action)
                     (return #f)
                     (operating-system-bootcfg
                      os
                      (if (eq? 'init action)
                          '()
                          (map boot-parameters->menu-entry
                               (profile-boot-parameters))))))
       (bootcfg-file -> (bootloader-configuration-file bootloader))
       (bootloader-installer
        (let ((installer (bootloader-installer bootloader))
              (target    (or target "/")))
          (bootloader-installer-derivation installer
                                           bootloader-package
                                           bootloader-target target)))

       ;; For 'init' and 'reconfigure', always build BOOTCFG, even if
       ;; --no-bootloader is passed, because we then use it as a GC root.
       ;; See <http://bugs.gnu.org/21068>.
       (drvs   -> (if (memq action '(init reconfigure))
                      (if (and install-bootloader? bootloader-package)
                          (list sys bootcfg
				bootloader-package
				bootloader-installer)
                          (list sys bootcfg))
                      (list sys)))
       (%         (if derivations-only?
                      (return (for-each (compose println derivation-file-name)
                                        drvs))
                      (maybe-build drvs #:dry-run? dry-run?
                                   #:use-substitutes? use-substitutes?))))

    (if (or dry-run? derivations-only?)
        (return #f)
        (begin
          (for-each (compose println derivation->output-path)
                    drvs)

          (case action
            ((reconfigure)
             (mbegin %store-monad
               (switch-to-system os)
               (mwhen install-bootloader?
                 (install-bootloader bootloader-installer
                                     #:bootcfg bootcfg
                                     #:bootcfg-file bootcfg-file
                                     #:target "/"))))
            ((init)
             (newline)
             (format #t (G_ "initializing operating system under '~a'...~%")
                     target)
             (install sys (canonicalize-path target)
                      #:install-bootloader? install-bootloader?
                      #:bootcfg bootcfg
                      #:bootcfg-file bootcfg-file
                      #:bootloader-installer bootloader-installer))
            (else
             ;; All we had to do was to build SYS and maybe register an
             ;; indirect GC root.
             (let ((output (derivation->output-path sys)))
               (mbegin %store-monad
                 (mwhen gc-root
                   (register-root* (list output) gc-root))
                 (return output)))))))))

(define (export-extension-graph os port)
  "Export the service extension graph of OS to PORT."
  (let* ((services (operating-system-services os))
         (system   (find (lambda (service)
                           (eq? (service-kind service) system-service-type))
                         services)))
    (export-graph (list system) (current-output-port)
                  #:node-type (service-node-type services)
                  #:reverse-edges? #t)))

(define (export-shepherd-graph os port)
  "Export the graph of shepherd services of OS to PORT."
  (let* ((services  (operating-system-services os))
         (pid1      (fold-services services
                                   #:target-type shepherd-root-service-type))
         (shepherds (service-value pid1))         ;list of <shepherd-service>
         (sinks     (filter (lambda (service)
                              (null? (shepherd-service-requirement service)))
                            shepherds)))
    (export-graph sinks (current-output-port)
                  #:node-type (shepherd-service-node-type shepherds)
                  #:reverse-edges? #t)))


;;;
;;; Options.
;;;

(define (show-help)
  (display (G_ "Usage: guix system [OPTION ...] ACTION [ARG ...] [FILE]
Build the operating system declared in FILE according to ACTION.
Some ACTIONS support additional ARGS.\n"))
  (newline)
  (display (G_ "The valid values for ACTION are:\n"))
  (newline)
  (display (G_ "\
   search           search for existing service types\n"))
  (display (G_ "\
   reconfigure      switch to a new operating system configuration\n"))
  (display (G_ "\
   roll-back        switch to the previous operating system configuration\n"))
  (display (G_ "\
   switch-generation switch to an existing operating system configuration\n"))
  (display (G_ "\
   list-generations list the system generations\n"))
  (display (G_ "\
   build            build the operating system without installing anything\n"))
  (display (G_ "\
   container        build a container that shares the host's store\n"))
  (display (G_ "\
   vm               build a virtual machine image that shares the host's store\n"))
  (display (G_ "\
   vm-image         build a freestanding virtual machine image\n"))
  (display (G_ "\
   disk-image       build a disk image, suitable for a USB stick\n"))
  (display (G_ "\
   docker-image     build a Docker image\n"))
  (display (G_ "\
   init             initialize a root file system to run GNU\n"))
  (display (G_ "\
   extension-graph  emit the service extension graph in Dot format\n"))
  (display (G_ "\
   shepherd-graph   emit the graph of shepherd services in Dot format\n"))

  (show-build-options-help)
  (display (G_ "
  -d, --derivation       return the derivation of the given system"))
  (display (G_ "
  -e, --expression=EXPR  consider the operating-system EXPR evaluates to
                         instead of reading FILE, when applicable"))
  (display (G_ "
      --on-error=STRATEGY
                         apply STRATEGY when an error occurs while reading FILE"))
  (display (G_ "
      --file-system-type=TYPE
                         for 'disk-image', produce a root file system of TYPE
                         (one of 'ext4', 'iso9660')"))
  (display (G_ "
      --image-size=SIZE  for 'vm-image', produce an image of SIZE"))
  (display (G_ "
      --no-bootloader    for 'init', do not install a bootloader"))
  (display (G_ "
      --share=SPEC       for 'vm', share host file system according to SPEC"))
  (display (G_ "
  -r, --root=FILE        for 'vm', 'vm-image', 'disk-image', 'container',
                         and 'build', make FILE a symlink to the result, and
                         register it as a garbage collector root"))
  (display (G_ "
      --expose=SPEC      for 'vm', expose host file system according to SPEC"))
  (display (G_ "
      --full-boot        for 'vm', make a full boot sequence"))
  (display (G_ "
      --skip-checks      skip file system and initrd module safety checks"))
  (newline)
  (display (G_ "
  -h, --help             display this help and exit"))
  (display (G_ "
  -V, --version          display version information and exit"))
  (newline)
  (show-bug-report-information))

(define %options
  ;; Specifications of the command-line options.
  (cons* (option '(#\h "help") #f #f
                 (lambda args
                   (show-help)
                   (exit 0)))
         (option '(#\V "version") #f #f
                 (lambda args
                   (show-version-and-exit "guix system")))
         (option '(#\e "expression") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'expression arg result)))
         (option '(#\d "derivation") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'derivations-only? #t result)))
         (option '("on-error") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'on-error (string->symbol arg)
                               result)))
         (option '(#\t "file-system-type") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'file-system-type arg
                               result)))
         (option '("image-size") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'image-size (size->number arg)
                               result)))
         (option '("no-bootloader" "no-grub") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'install-bootloader? #f result)))
         (option '("full-boot") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'full-boot? #t result)))
         (option '("skip-checks") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'skip-safety-checks? #t result)))

         (option '("share") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'file-system-mapping
                               (specification->file-system-mapping arg #t)
                               result)))
         (option '("expose") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'file-system-mapping
                               (specification->file-system-mapping arg #f)
                               result)))

         (option '(#\n "dry-run") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'dry-run? #t (alist-cons 'graft? #f result))))
         (option '(#\s "system") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'system arg
                               (alist-delete 'system result eq?))))
         (option '(#\r "root") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'gc-root arg result)))
         %standard-build-options))

(define %default-options
  ;; Alist of default option values.
  `((system . ,(%current-system))
    (substitutes? . #t)
    (build-hook? . #t)
    (graft? . #t)
    (verbosity . 0)
    (file-system-type . "ext4")
    (image-size . guess)
    (install-bootloader? . #t)))


;;;
;;; Entry point.
;;;

(define (process-action action args opts)
  "Process ACTION, a sub-command, with the arguments are listed in ARGS.
ACTION must be one of the sub-commands that takes an operating system
declaration as an argument (a file name.)  OPTS is the raw alist of options
resulting from command-line parsing."
  (let* ((file        (match args
                        (() #f)
                        ((x . _) x)))
         (expr        (assoc-ref opts 'expression))
         (system      (assoc-ref opts 'system))
         (os          (cond
                       ((and expr file)
                        (leave
                         (G_ "both file and expression cannot be specified~%")))
                       (expr
                        (read/eval expr))
                       (file
                        (load* file %user-module
                                    #:on-error (assoc-ref opts 'on-error)))
                       (else
                        (leave (G_ "no configuration specified~%")))))

         (dry?        (assoc-ref opts 'dry-run?))
         (bootloader? (assoc-ref opts 'install-bootloader?))
         (target      (match args
                        ((first second) second)
                        (_ #f)))
         (bootloader-target
                      (and bootloader?
                           (bootloader-configuration-target
                            (operating-system-bootloader os)))))

    (with-store store
      (set-build-options-from-command-line store opts)

      (run-with-store store
        (mbegin %store-monad
          (set-guile-for-build (default-guile))
          (case action
            ((extension-graph)
             (export-extension-graph os (current-output-port)))
            ((shepherd-graph)
             (export-shepherd-graph os (current-output-port)))
            (else
             (unless (memq action '(build init))
               (warn-about-old-distro #:suggested-command
                                      "guix system reconfigure"))

             (perform-action action os
                             #:dry-run? dry?
                             #:derivations-only? (assoc-ref opts
                                                            'derivations-only?)
                             #:use-substitutes? (assoc-ref opts 'substitutes?)
                             #:skip-safety-checks?
                             (assoc-ref opts 'skip-safety-checks?)
                             #:file-system-type (assoc-ref opts 'file-system-type)
                             #:image-size (assoc-ref opts 'image-size)
                             #:full-boot? (assoc-ref opts 'full-boot?)
                             #:mappings (filter-map (match-lambda
                                                      (('file-system-mapping . m)
                                                       m)
                                                      (_ #f))
                                                    opts)
                             #:install-bootloader? bootloader?
                             #:target target
                             #:bootloader-target bootloader-target
                             #:gc-root (assoc-ref opts 'gc-root)))))
        #:system system))))

(define (resolve-subcommand name)
  (let ((module (resolve-interface
                 `(guix scripts system ,(string->symbol name))))
        (proc (string->symbol (string-append "guix-system-" name))))
    (module-ref module proc)))

(define (process-command command args opts)
  "Process COMMAND, one of the 'guix system' sub-commands.  ARGS is its
argument list and OPTS is the option alist."
  (case command
    ;; The following commands do not need to use the store, and they do not need
    ;; an operating system configuration file.
    ((list-generations)
     (let ((pattern (match args
                      (() "")
                      ((pattern) pattern)
                      (x (leave (G_ "wrong number of arguments~%"))))))
       (list-generations pattern)))
    ((search)
     (apply (resolve-subcommand "search") args))
    ;; The following commands need to use the store, but they do not need an
    ;; operating system configuration file.
    ((switch-generation)
     (let ((pattern (match args
                      ((pattern) pattern)
                      (x (leave (G_ "wrong number of arguments~%"))))))
       (with-store store
         (set-build-options-from-command-line store opts)
         (switch-to-system-generation store pattern))))
    ((roll-back)
     (let ((pattern (match args
                      (() "")
                      (x (leave (G_ "wrong number of arguments~%"))))))
       (with-store store
         (set-build-options-from-command-line store opts)
         (roll-back-system store))))
    ;; The following commands need to use the store, and they also
    ;; need an operating system configuration file.
    (else (process-action command args opts))))

(define (guix-system . args)
  (define (parse-sub-command arg result)
    ;; Parse sub-command ARG and augment RESULT accordingly.
    (if (assoc-ref result 'action)
        (alist-cons 'argument arg result)
        (let ((action (string->symbol arg)))
          (case action
            ((build container vm vm-image disk-image reconfigure init
              extension-graph shepherd-graph list-generations roll-back
              switch-generation search docker-image)
             (alist-cons 'action action result))
            (else (leave (G_ "~a: unknown action~%") action))))))

  (define (match-pair car)
    ;; Return a procedure that matches a pair with CAR.
    (match-lambda
      ((head . tail)
       (and (eq? car head) tail))
      (_ #f)))

  (define (option-arguments opts)
    ;; Extract the plain arguments from OPTS.
    (let* ((args   (reverse (filter-map (match-pair 'argument) opts)))
           (count  (length args))
           (action (assoc-ref opts 'action))
           (expr   (assoc-ref opts 'expression)))
      (define (fail)
        (leave (G_ "wrong number of arguments for action '~a'~%")
               action))

      (unless action
        (format (current-error-port)
                (G_ "guix system: missing command name~%"))
        (format (current-error-port)
                (G_ "Try 'guix system --help' for more information.~%"))
        (exit 1))

      (case action
        ((build container vm vm-image disk-image docker-image reconfigure)
         (unless (or (= count 1)
                     (and expr (= count 0)))
           (fail)))
        ((init)
         (unless (= count 2)
           (fail))))
      args))

  (with-error-handling
    (let* ((opts     (parse-command-line args %options
                                         (list %default-options)
                                         #:argument-handler
                                         parse-sub-command))
           (args     (option-arguments opts))
           (command  (assoc-ref opts 'action)))
      (parameterize ((%graft? (assoc-ref opts 'graft?))
                     (current-terminal-columns (terminal-columns)))
        (process-command command args opts)))))

;;; Local Variables:
;;; eval: (put 'call-with-service-upgrade-info 'scheme-indent-function 1)
;;; End:

;;; system.scm ends here