aboutsummaryrefslogtreecommitdiff
path: root/gnu/machine/ssh.scm
blob: 35b42add48e85a25af2660a4aef250fbafaa01cf (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
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.org>
;;; Copyright © 2020 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 machine ssh)
  #:use-module (gnu bootloader)
  #:use-module (gnu machine)
  #:autoload   (gnu packages gnupg) (guile-gcrypt)
  #:use-module (gnu system)
  #:use-module (gnu system file-systems)
  #:use-module (gnu system uuid)
  #:use-module ((gnu services) #:select (sexp->system-provenance))
  #:use-module (guix diagnostics)
  #:use-module (guix gexp)
  #:use-module (guix i18n)
  #:use-module (guix modules)
  #:use-module (guix monads)
  #:use-module (guix pki)
  #:use-module (guix records)
  #:use-module (guix remote)
  #:use-module (guix scripts system reconfigure)
  #:use-module (guix ssh)
  #:use-module (guix store)
  #:use-module (guix utils)
  #:use-module (gcrypt pk-crypto)
  #:use-module (ice-9 format)
  #:use-module (ice-9 match)
  #:use-module (ice-9 textual-ports)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:export (managed-host-environment-type

            machine-ssh-configuration
            machine-ssh-configuration?
            machine-ssh-configuration

            machine-ssh-configuration-host-name
            machine-ssh-configuration-build-locally?
            machine-ssh-configuration-authorize?
            machine-ssh-configuration-allow-downgrades?
            machine-ssh-configuration-port
            machine-ssh-configuration-user
            machine-ssh-configuration-host-key
            machine-ssh-configuration-session))

;;; Commentary:
;;;
;;; This module implements remote evaluation and system deployment for
;;; machines that are accessible over SSH and have a known host-name. In the
;;; sense of the broader "machine" interface, we describe the environment for
;;; such machines as 'managed-host.
;;;
;;; Code:


;;;
;;; Parameters for the SSH client.
;;;

(define-record-type* <machine-ssh-configuration> machine-ssh-configuration
  make-machine-ssh-configuration
  machine-ssh-configuration?
  (host-name      machine-ssh-configuration-host-name)     ; string
  (system         machine-ssh-configuration-system)        ; string
  (build-locally? machine-ssh-configuration-build-locally? ; boolean
                  (default #t))
  (authorize?     machine-ssh-configuration-authorize?     ; boolean
                  (default #t))
  (allow-downgrades? machine-ssh-configuration-allow-downgrades? ; boolean
                     (default #f))
  (port           machine-ssh-configuration-port           ; integer
                  (default 22))
  (user           machine-ssh-configuration-user           ; string
                  (default "root"))
  (identity       machine-ssh-configuration-identity       ; path to a private key
                  (default #f))
  (session        machine-ssh-configuration-session        ; session
                  (default #f))
  (host-key       machine-ssh-configuration-host-key       ; #f | string
                  (default #f)))

(define (machine-ssh-session machine)
  "Return the SSH session that was given in MACHINE's configuration, or create
one from the configuration's parameters if one was not provided."
  (maybe-raise-unsupported-configuration-error machine)
  (let ((config (machine-configuration machine)))
    (or (machine-ssh-configuration-session config)
        (let ((host-name (machine-ssh-configuration-host-name config))
              (user (machine-ssh-configuration-user config))
              (port (machine-ssh-configuration-port config))
              (identity (machine-ssh-configuration-identity config))
              (host-key (machine-ssh-configuration-host-key config)))
          (unless host-key
            (warning (G_ "<machine-ssh-configuration> without a 'host-key' \
is deprecated~%")))
          (open-ssh-session host-name
                            #:user user
                            #:port port
                            #:identity identity
                            #:host-key host-key)))))


;;;
;;; Remote evaluation.
;;;

(define (machine-become-command machine)
  "Return as a list of strings the program and arguments necessary to run a
shell command with escalated privileges for MACHINE's configuration."
  (if (string= "root" (machine-ssh-configuration-user
                       (machine-configuration machine)))
      '()
      '("/run/setuid-programs/sudo" "-n" "--")))

(define (managed-host-remote-eval machine exp)
  "Internal implementation of 'machine-remote-eval' for MACHINE instances with
an environment type of 'managed-host."
  (maybe-raise-unsupported-configuration-error machine)
  (let ((config (machine-configuration machine)))
    (remote-eval exp (machine-ssh-session machine)
                 #:build-locally?
                 (machine-ssh-configuration-build-locally? config)
                 #:system
                 (machine-ssh-configuration-system config)
                 #:become-command
                 (machine-become-command machine))))


;;;
;;; Safety checks.
;;;

;; Assertion to be executed remotely.  This abstraction exists to allow us to
;; gather a list of expressions to be evaluated and eventually evaluate them
;; all at once instead of one by one.  (This is pretty much a monad.)
(define-record-type <remote-assertion>
  (remote-assertion exp proc)
  remote-assertion?
  (exp   remote-assertion-expression)
  (proc  remote-assertion-procedure))

(define-syntax-rule (remote-let ((var exp)) body ...)
  "Return a <remote-assertion> that binds VAR to the result of evaluating EXP,
a gexp, remotely, and evaluate BODY in that context."
  (remote-assertion exp (lambda (var) body ...)))

(define (machine-check-file-system-availability machine)
  "Return a list of <remote-assertion> that raise a '&message' error condition
if any of the file-systems specified in MACHINE's 'system' declaration do not
exist on the machine."
  (define file-systems
    (filter (lambda (fs)
              (and (file-system-mount? fs)
                   (not (member (file-system-type fs)
                                %pseudo-file-system-types))
                   ;; Don't try to validate network file systems.
                   (not (string-prefix? "nfs" (file-system-type fs)))
                   (not (memq 'bind-mount (file-system-flags fs)))))
            (operating-system-file-systems (machine-operating-system machine))))

  (define (check-literal-file-system fs)
    (remote-let ((errno #~(catch 'system-error
                            (lambda ()
                              (stat #$(file-system-device fs))
                              #t)
                            (lambda args
                              (system-error-errno args)))))
      (when (number? errno)
        (raise (formatted-message (G_ "device '~a' not found: ~a")
                                  (file-system-device fs)
                                  (strerror errno))))))

  (define (check-labeled-file-system fs)
    (define remote-exp
      (with-imported-modules (source-module-closure
                              '((gnu build file-systems)))
        #~(begin
            (use-modules (gnu build file-systems))
            (find-partition-by-label #$(file-system-label->string
                                        (file-system-device fs))))))

    (remote-let ((result remote-exp))
      (unless result
        (raise (formatted-message (G_ "no file system with label '~a'")
                                  (file-system-label->string
                                   (file-system-device fs)))))))

  (define (check-uuid-file-system fs)
    (define remote-exp
      (with-imported-modules (source-module-closure
                              '((gnu build file-systems)
                                (gnu system uuid)))
        #~(begin
            (use-modules (gnu build file-systems)
                         (gnu system uuid))

            (let ((uuid (uuid #$(uuid->string (file-system-device fs))
                              '#$(uuid-type (file-system-device fs)))))
              (find-partition-by-uuid uuid)))))

    (remote-let ((result remote-exp))
      (unless result
        (raise (formatted-message (G_ "no file system with UUID '~a'")
                                  (uuid->string (file-system-device fs)))))))

  (append (map check-literal-file-system
               (filter (lambda (fs)
                         (string? (file-system-device fs)))
                       file-systems))
          (map check-labeled-file-system
               (filter (lambda (fs)
                         (file-system-label? (file-system-device fs)))
                       file-systems))
          (map check-uuid-file-system
               (filter (lambda (fs)
                         (uuid? (file-system-device fs)))
                       file-systems))))

(define (machine-check-initrd-modules machine)
  "Return a list of <remote-assertion> that raise a '&message' error condition
if any of the modules needed by 'needed-for-boot' file systems in MACHINE are
not available in the initrd."
  (define file-systems
    (filter file-system-needed-for-boot?
            (operating-system-file-systems (machine-operating-system machine))))

  (define (missing-modules fs)
    (define remote-exp
      (let ((device (file-system-device fs)))
        (with-imported-modules (source-module-closure
                                '((gnu build file-systems)
                                  (gnu build linux-modules)
                                  (gnu system uuid)))
          #~(begin
              (use-modules (gnu build file-systems)
                           (gnu build linux-modules)
                           (gnu system uuid))

              (define dev
                #$(cond ((string? device) device)
                        ((uuid? device) #~(find-partition-by-uuid
                                           (string->uuid
                                            #$(uuid->string device))))
                        ((file-system-label? device)
                         #~(find-partition-by-label
                            #$(file-system-label->string device)))))

              (missing-modules dev '#$(operating-system-initrd-modules
                                       (machine-operating-system machine)))))))

    (remote-let ((missing remote-exp))
      (unless (null? missing)
        (raise (condition
                (&message
                 (message (format #f (G_ "missing modules for ~a:~{ ~a~}~%")
                                  (file-system-device fs)
                                  missing))))))))

  (map missing-modules file-systems))

(define* (machine-check-forward-update machine)
  "Check whether we are making a forward update for MACHINE.  Depending on its
'allow-upgrades?' field, raise an error or display a warning if we are
potentially downgrading it."
  (define config
    (machine-configuration machine))

  (define validate-reconfigure
    (if (machine-ssh-configuration-allow-downgrades? config)
        warn-about-backward-reconfigure
        ensure-forward-reconfigure))

  (remote-let ((provenance #~(call-with-input-file
                                 "/run/current-system/provenance"
                               read)))
    (define channels
      (sexp->system-provenance provenance))

    (check-forward-update validate-reconfigure
                          #:current-channels channels)))

(define (machine-check-building-for-appropriate-system machine)
  "Raise a '&message' error condition if MACHINE is configured to be built
locally and the 'system' field does not match the '%current-system' reported
by MACHINE."
  (let ((config (machine-configuration machine))
        (system (remote-system (machine-ssh-session machine))))
    (when (and (machine-ssh-configuration-build-locally? config)
               (not (string= system (machine-ssh-configuration-system config))))
      (raise (formatted-message (G_ "incorrect target system\
 ('~a' was given, while the system reports that it is '~a')~%")
                                (machine-ssh-configuration-system config)
                                system)))))

(define (check-deployment-sanity machine)
  "Raise a '&message' error condition if it is clear that deploying MACHINE's
'system' declaration would fail."
  (define assertions
    (append (machine-check-file-system-availability machine)
            (machine-check-initrd-modules machine)
            (list (machine-check-forward-update machine))))

  (define aggregate-exp
    ;; Gather all the expressions so that a single round-trip is enough to
    ;; evaluate all the ASSERTIONS remotely.
    #~(map (lambda (file)
             (false-if-exception (primitive-load file)))
           '#$(map (lambda (assertion)
                     (scheme-file "remote-assertion.scm"
                                  (remote-assertion-expression assertion)))
                   assertions)))

  ;; First check MACHINE's system type--an incorrect value for 'system' would
  ;; cause subsequent invocations of 'remote-eval' to fail.
  (machine-check-building-for-appropriate-system machine)

  (mlet %store-monad ((values (machine-remote-eval machine aggregate-exp)))
    (for-each (lambda (proc value)
                (proc value))
              (map remote-assertion-procedure assertions)
              values)
    (return #t)))


;;;
;;; System deployment.
;;;

(define (machine-boot-parameters machine)
  "Monadic procedure returning a list of 'boot-parameters' for the generations
of MACHINE's system profile, ordered from most recent to oldest."
  (define bootable-kernel-arguments
    (@@ (gnu system) bootable-kernel-arguments))

  (define remote-exp
    (with-extensions (list guile-gcrypt)
      (with-imported-modules (source-module-closure '((guix config)
                                                      (guix profiles)))
        #~(begin
            (use-modules (guix config)
                         (guix profiles)
                         (ice-9 textual-ports))

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

            (define (read-file path)
              (call-with-input-file path
                (lambda (port)
                  (get-string-all port))))

            (map (lambda (generation)
                   (let* ((system-path (generation-file-name %system-profile
                                                             generation))
                          (boot-parameters-path (string-append system-path
                                                               "/parameters"))
                          (time (stat:mtime (lstat system-path))))
                     (list generation
                           system-path
                           time
                           (read-file boot-parameters-path))))
                 (reverse (generation-numbers %system-profile)))))))

  (mlet* %store-monad ((generations (machine-remote-eval machine remote-exp)))
    (return
     (map (lambda (generation)
            (match generation
              ((generation system-path time serialized-params)
               (let* ((params (call-with-input-string serialized-params
                                read-boot-parameters))
                      (root (boot-parameters-root-device params))
                      (label (boot-parameters-label params)))
                 (boot-parameters
                  (inherit params)
                  (label
                   (string-append label " (#"
                                  (number->string generation) ", "
                                  (let ((time (make-time time-utc 0 time)))
                                    (date->string (time-utc->date time)
                                                  "~Y-~m-~d ~H:~M"))
                                  ")"))
                  (kernel-arguments
                   (append (bootable-kernel-arguments system-path root)
                           (boot-parameters-kernel-arguments params))))))))
          generations))))

(define-syntax-rule (with-roll-back should-roll-back? mbody ...)
  "Catch exceptions that arise when binding MBODY, a monadic expression in
%STORE-MONAD, and collect their arguments in a &deploy-error condition, with
the 'should-roll-back' field set to SHOULD-ROLL-BACK?"
  (catch #t
    (lambda ()
      mbody ...)
    (lambda args
      (raise (condition (&deploy-error
                         (should-roll-back should-roll-back?)
                         (captured-args args)))))))

(define (deploy-managed-host machine)
  "Internal implementation of 'deploy-machine' for MACHINE instances with an
environment type of 'managed-host."
  (maybe-raise-unsupported-configuration-error machine)
  (when (machine-ssh-configuration-authorize?
         (machine-configuration machine))
    (unless (file-exists? %public-key-file)
      (raise (formatted-message (G_ "no signing key '~a'. \
have you run 'guix archive --generate-key?'")
                                %public-key-file)))
    (remote-authorize-signing-key (call-with-input-file %public-key-file
                                    (lambda (port)
                                      (string->canonical-sexp
                                       (get-string-all port))))
                                  (machine-ssh-session machine)
                                  (machine-become-command machine)))
  (mlet %store-monad ((_ (check-deployment-sanity machine))
                      (boot-parameters (machine-boot-parameters machine)))
    (let* ((os (machine-operating-system machine))
           (eval (cut machine-remote-eval machine <>))
           (menu-entries (map boot-parameters->menu-entry boot-parameters))
           (bootloader-configuration (operating-system-bootloader os))
           (bootcfg (operating-system-bootcfg os menu-entries)))
      (mbegin %store-monad
        (with-roll-back #f
          (switch-to-system eval os))
        (with-roll-back #t
          (mbegin %store-monad
            (upgrade-shepherd-services eval os)
            (install-bootloader eval bootloader-configuration bootcfg)))))))


;;;
;;; Roll-back.
;;;

(define (roll-back-managed-host machine)
  "Internal implementation of 'roll-back-machine' for MACHINE instances with
an environment type of 'managed-host."
  (define remote-exp
    (with-extensions (list guile-gcrypt)
      (with-imported-modules (source-module-closure '((guix config)
                                                      (guix profiles)))
        #~(begin
            (use-modules (guix config)
                         (guix profiles))

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

            (define target-generation
              (relative-generation %system-profile -1))

            (if target-generation
                (switch-to-generation %system-profile target-generation)
                'error)))))

  (define roll-back-failure
    (condition (&message (message (G_ "could not roll-back machine")))))

  (mlet* %store-monad ((boot-parameters (machine-boot-parameters machine))
                       (_ -> (if (< (length boot-parameters) 2)
                                 (raise roll-back-failure)))
                       (entries -> (map boot-parameters->menu-entry
                                        (list (second boot-parameters))))
                       (old-entries -> (map boot-parameters->menu-entry
                                            (drop boot-parameters 2)))
                       (bootloader -> (operating-system-bootloader
                                       (machine-operating-system machine)))
                       (bootcfg (lower-object
                                 ((bootloader-configuration-file-generator
                                   (bootloader-configuration-bootloader
                                    bootloader))
                                  bootloader entries
                                  #:old-entries old-entries)))
                       (remote-result (machine-remote-eval machine remote-exp)))
    (when (eqv? 'error remote-result)
      (raise roll-back-failure))))


;;;
;;; Environment type.
;;;

(define managed-host-environment-type
  (environment-type
   (machine-remote-eval managed-host-remote-eval)
   (deploy-machine      deploy-managed-host)
   (roll-back-machine   roll-back-managed-host)
   (name                'managed-host-environment-type)
   (description         "Provisioning for machines that are accessible over SSH
and have a known host-name. This entails little more than maintaining an SSH
connection to the host.")))

(define (maybe-raise-unsupported-configuration-error machine)
  "Raise an error if MACHINE's configuration is not an instance of
<machine-ssh-configuration>."
  (let ((config (machine-configuration machine))
        (environment (environment-type-name (machine-environment machine))))
    (unless (and config (machine-ssh-configuration? config))
      (raise (formatted-message (G_ "unsupported machine configuration '~a'
for environment of type '~a'")
                                config
                                environment)))))

;; Local Variables:
;; eval: (put 'remote-let 'scheme-indent-function 1)
;; End: