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db4fdc04 | 1 | ;;; GNU Guix --- Functional package management for GNU |
94af9daa | 2 | ;;; Copyright © 2015, 2016 Ludovic Courtès <ludo@gnu.org> |
4d343a14 | 3 | ;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com> |
db4fdc04 LC |
4 | ;;; |
5 | ;;; This file is part of GNU Guix. | |
6 | ;;; | |
7 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
8 | ;;; under the terms of the GNU General Public License as published by | |
9 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
10 | ;;; your option) any later version. | |
11 | ;;; | |
12 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
13 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | ;;; GNU General Public License for more details. | |
16 | ;;; | |
17 | ;;; You should have received a copy of the GNU General Public License | |
18 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
19 | ||
20 | (define-module (gnu services) | |
bebc8681 | 21 | #:use-module (guix gexp) |
0adfe95a LC |
22 | #:use-module (guix monads) |
23 | #:use-module (guix store) | |
db4fdc04 | 24 | #:use-module (guix records) |
af4c3fd5 | 25 | #:use-module (guix profiles) |
0adfe95a LC |
26 | #:use-module (guix sets) |
27 | #:use-module (guix ui) | |
232ccbef | 28 | #:use-module (guix modules) |
0adfe95a LC |
29 | #:use-module (gnu packages base) |
30 | #:use-module (gnu packages bash) | |
31 | #:use-module (srfi srfi-1) | |
32 | #:use-module (srfi srfi-9) | |
33 | #:use-module (srfi srfi-9 gnu) | |
34 | #:use-module (srfi srfi-26) | |
35 | #:use-module (srfi srfi-34) | |
36 | #:use-module (srfi srfi-35) | |
37 | #:use-module (ice-9 vlist) | |
38 | #:use-module (ice-9 match) | |
39 | #:export (service-extension | |
40 | service-extension? | |
41 | ||
42 | service-type | |
43 | service-type? | |
5152d13b LC |
44 | service-type-name |
45 | service-type-extensions | |
46 | service-type-compose | |
47 | service-type-extend | |
0adfe95a | 48 | |
db4fdc04 | 49 | service |
0adfe95a LC |
50 | service? |
51 | service-kind | |
52 | service-parameters | |
53 | ||
71654dfd | 54 | simple-service |
cd6f6c22 | 55 | modify-services |
5152d13b | 56 | service-back-edges |
0adfe95a LC |
57 | fold-services |
58 | ||
59 | service-error? | |
60 | missing-target-service-error? | |
61 | missing-target-service-error-service | |
62 | missing-target-service-error-target-type | |
63 | ambiguous-target-service-error? | |
64 | ambiguous-target-service-error-service | |
65 | ambiguous-target-service-error-target-type | |
66 | ||
d62e201c | 67 | system-service-type |
0adfe95a | 68 | boot-service-type |
be7be9e8 | 69 | cleanup-service-type |
0adfe95a LC |
70 | activation-service-type |
71 | activation-service->script | |
a241a7ac | 72 | %linux-bare-metal-service |
0adfe95a LC |
73 | etc-service-type |
74 | etc-directory | |
75 | setuid-program-service-type | |
af4c3fd5 | 76 | profile-service-type |
0adfe95a | 77 | firmware-service-type |
e0b47290 | 78 | gc-root-service-type |
0adfe95a LC |
79 | |
80 | %boot-service | |
81 | %activation-service | |
82 | etc-service | |
83 | ||
84 | file-union)) ;XXX: for lack of a better place | |
85 | ||
86 | ;;; Comment: | |
87 | ;;; | |
88 | ;;; This module defines a broad notion of "service types" and "services." | |
db4fdc04 | 89 | ;;; |
0adfe95a LC |
90 | ;;; A service type describe how its instances extend instances of other |
91 | ;;; service types. For instance, some services extend the instance of | |
92 | ;;; ACCOUNT-SERVICE-TYPE by providing it with accounts and groups to create; | |
d4053c71 AK |
93 | ;;; others extend SHEPHERD-ROOT-SERVICE-TYPE by passing it instances of |
94 | ;;; <shepherd-service>. | |
0adfe95a LC |
95 | ;;; |
96 | ;;; When applicable, the service type defines how it can itself be extended, | |
97 | ;;; by providing one procedure to compose extensions, and one procedure to | |
98 | ;;; extend itself. | |
99 | ;;; | |
d62e201c LC |
100 | ;;; A notable service type is SYSTEM-SERVICE-TYPE, which has a single |
101 | ;;; instance, which is the root of the service DAG. Its value is the | |
102 | ;;; derivation that produces the 'system' directory as returned by | |
103 | ;;; 'operating-system-derivation'. | |
0adfe95a LC |
104 | ;;; |
105 | ;;; The 'fold-services' procedure can be passed a list of procedures, which it | |
106 | ;;; "folds" by propagating extensions down the graph; it returns the root | |
107 | ;;; service after the applying all its extensions. | |
db4fdc04 LC |
108 | ;;; |
109 | ;;; Code: | |
110 | ||
0adfe95a LC |
111 | (define-record-type <service-extension> |
112 | (service-extension target compute) | |
113 | service-extension? | |
114 | (target service-extension-target) ;<service-type> | |
115 | (compute service-extension-compute)) ;params -> params | |
116 | ||
117 | (define-record-type* <service-type> service-type make-service-type | |
118 | service-type? | |
119 | (name service-type-name) ;symbol (for debugging) | |
120 | ||
121 | ;; Things extended by services of this type. | |
122 | (extensions service-type-extensions) ;list of <service-extensions> | |
123 | ||
124 | ;; Given a list of extensions, "compose" them. | |
125 | (compose service-type-compose ;list of Any -> Any | |
126 | (default #f)) | |
127 | ||
128 | ;; Extend the services' own parameters with the extension composition. | |
129 | (extend service-type-extend ;list of Any -> parameters | |
130 | (default #f))) | |
131 | ||
132 | (define (write-service-type type port) | |
133 | (format port "#<service-type ~a ~a>" | |
134 | (service-type-name type) | |
135 | (number->string (object-address type) 16))) | |
136 | ||
137 | (set-record-type-printer! <service-type> write-service-type) | |
138 | ||
139 | ;; Services of a given type. | |
140 | (define-record-type <service> | |
141 | (service type parameters) | |
db4fdc04 | 142 | service? |
0adfe95a LC |
143 | (type service-kind) |
144 | (parameters service-parameters)) | |
145 | ||
71654dfd LC |
146 | (define (simple-service name target value) |
147 | "Return a service that extends TARGET with VALUE. This works by creating a | |
148 | singleton service type NAME, of which the returned service is an instance." | |
149 | (let* ((extension (service-extension target identity)) | |
150 | (type (service-type (name name) | |
151 | (extensions (list extension))))) | |
152 | (service type value))) | |
0adfe95a | 153 | |
cd6f6c22 LC |
154 | (define-syntax %modify-service |
155 | (syntax-rules (=>) | |
156 | ((_ service) | |
157 | service) | |
158 | ((_ svc (kind param => exp ...) clauses ...) | |
159 | (if (eq? (service-kind svc) kind) | |
160 | (let ((param (service-parameters svc))) | |
161 | (service (service-kind svc) | |
162 | (begin exp ...))) | |
163 | (%modify-service svc clauses ...))))) | |
164 | ||
165 | (define-syntax modify-services | |
166 | (syntax-rules () | |
4d343a14 CM |
167 | "Modify the services listed in SERVICES according to CLAUSES and return |
168 | the resulting list of services. Each clause must have the form: | |
cd6f6c22 LC |
169 | |
170 | (TYPE VARIABLE => BODY) | |
171 | ||
172 | where TYPE is a service type, such as 'guix-service-type', and VARIABLE is an | |
173 | identifier that is bound within BODY to the value of the service of that | |
174 | TYPE. Consider this example: | |
175 | ||
176 | (modify-services %base-services | |
177 | (guix-service-type config => | |
178 | (guix-configuration | |
179 | (inherit config) | |
180 | (use-substitutes? #f) | |
181 | (extra-options '(\"--gc-keep-derivations\")))) | |
182 | (mingetty-service-type config => | |
183 | (mingetty-configuration | |
184 | (inherit config) | |
185 | (motd (plain-file \"motd\" \"Hi there!\"))))) | |
186 | ||
187 | It changes the configuration of the GUIX-SERVICE-TYPE instance, and that of | |
188 | all the MINGETTY-SERVICE-TYPE instances. | |
189 | ||
190 | This is a shorthand for (map (lambda (svc) ...) %base-services)." | |
191 | ((_ services clauses ...) | |
192 | (map (lambda (service) | |
193 | (%modify-service service clauses ...)) | |
194 | services)))) | |
0adfe95a LC |
195 | |
196 | \f | |
197 | ;;; | |
198 | ;;; Core services. | |
199 | ;;; | |
200 | ||
d62e201c LC |
201 | (define (system-derivation mentries mextensions) |
202 | "Return as a monadic value the derivation of the 'system' directory | |
203 | containing the given entries." | |
204 | (mlet %store-monad ((entries mentries) | |
205 | (extensions (sequence %store-monad mextensions))) | |
206 | (lower-object | |
207 | (file-union "system" | |
208 | (append entries (concatenate extensions)))))) | |
209 | ||
210 | (define system-service-type | |
211 | ;; This is the ultimate service type, the root of the service DAG. The | |
212 | ;; service of this type is extended by monadic name/item pairs. These items | |
213 | ;; end up in the "system directory" as returned by | |
214 | ;; 'operating-system-derivation'. | |
215 | (service-type (name 'system) | |
216 | (extensions '()) | |
217 | (compose identity) | |
218 | (extend system-derivation))) | |
219 | ||
3a391e68 | 220 | (define (compute-boot-script _ mexps) |
be7be9e8 | 221 | (mlet %store-monad ((gexps (sequence %store-monad mexps))) |
0adfe95a | 222 | (gexp->file "boot" |
d4053c71 | 223 | ;; Clean up and activate the system, then spawn shepherd. |
be7be9e8 | 224 | #~(begin #$@gexps)))) |
0adfe95a | 225 | |
d62e201c LC |
226 | (define (boot-script-entry mboot) |
227 | "Return, as a monadic value, an entry for the boot script in the system | |
228 | directory." | |
229 | (mlet %store-monad ((boot mboot)) | |
230 | (return `(("boot" ,boot))))) | |
231 | ||
0adfe95a LC |
232 | (define boot-service-type |
233 | ;; The service of this type is extended by being passed gexps as monadic | |
234 | ;; values. It aggregates them in a single script, as a monadic value, which | |
235 | ;; becomes its 'parameters'. It is the only service that extends nothing. | |
236 | (service-type (name 'boot) | |
d62e201c LC |
237 | (extensions |
238 | (list (service-extension system-service-type | |
239 | boot-script-entry))) | |
3a391e68 LC |
240 | (compose append) |
241 | (extend compute-boot-script))) | |
0adfe95a LC |
242 | |
243 | (define %boot-service | |
d62e201c | 244 | ;; The service that produces the boot script. |
0adfe95a | 245 | (service boot-service-type #t)) |
be7be9e8 LC |
246 | |
247 | (define (cleanup-gexp _) | |
248 | "Return as a monadic value a gexp to clean up /tmp and similar places upon | |
249 | boot." | |
fd129893 LC |
250 | (with-monad %store-monad |
251 | (with-imported-modules '((guix build utils)) | |
252 | (return #~(begin | |
253 | (use-modules (guix build utils)) | |
254 | ||
255 | ;; Clean out /tmp and /var/run. | |
256 | ;; | |
257 | ;; XXX This needs to happen before service activations, so it | |
258 | ;; has to be here, but this also implicitly assumes that /tmp | |
259 | ;; and /var/run are on the root partition. | |
260 | (letrec-syntax ((fail-safe (syntax-rules () | |
261 | ((_ exp rest ...) | |
262 | (begin | |
263 | (catch 'system-error | |
264 | (lambda () exp) | |
265 | (const #f)) | |
266 | (fail-safe rest ...))) | |
267 | ((_) | |
268 | #t)))) | |
269 | ;; Ignore I/O errors so the system can boot. | |
270 | (fail-safe | |
271 | (delete-file-recursively "/tmp") | |
272 | (delete-file-recursively "/var/run") | |
273 | (mkdir "/tmp") | |
274 | (chmod "/tmp" #o1777) | |
275 | (mkdir "/var/run") | |
276 | (chmod "/var/run" #o755)))))))) | |
be7be9e8 LC |
277 | |
278 | (define cleanup-service-type | |
279 | ;; Service that cleans things up in /tmp and similar. | |
280 | (service-type (name 'cleanup) | |
281 | (extensions | |
282 | (list (service-extension boot-service-type | |
283 | cleanup-gexp))))) | |
0adfe95a LC |
284 | |
285 | (define* (file-union name files) ;FIXME: Factorize. | |
286 | "Return a <computed-file> that builds a directory containing all of FILES. | |
287 | Each item in FILES must be a list where the first element is the file name to | |
288 | use in the new directory, and the second element is a gexp denoting the target | |
289 | file." | |
290 | (computed-file name | |
291 | #~(begin | |
292 | (mkdir #$output) | |
293 | (chdir #$output) | |
294 | #$@(map (match-lambda | |
295 | ((target source) | |
37dd1e6a LC |
296 | #~(begin |
297 | ;; Stat the source to abort early if it | |
298 | ;; does not exist. | |
299 | (stat #$source) | |
300 | ||
301 | (symlink #$source #$target)))) | |
0adfe95a LC |
302 | files)))) |
303 | ||
304 | (define (directory-union name things) | |
305 | "Return a directory that is the union of THINGS." | |
306 | (match things | |
307 | ((one) | |
308 | ;; Only one thing; return it. | |
309 | one) | |
310 | (_ | |
311 | (computed-file name | |
4ee96a79 LC |
312 | (with-imported-modules '((guix build union)) |
313 | #~(begin | |
314 | (use-modules (guix build union)) | |
315 | (union-build #$output '#$things))))))) | |
0adfe95a | 316 | |
0adfe95a LC |
317 | (define* (activation-service->script service) |
318 | "Return as a monadic value the activation script for SERVICE, a service of | |
319 | ACTIVATION-SCRIPT-TYPE." | |
320 | (activation-script (service-parameters service))) | |
321 | ||
322 | (define (activation-script gexps) | |
323 | "Return the system's activation script, which evaluates GEXPS." | |
0adfe95a LC |
324 | (define (service-activations) |
325 | ;; Return the activation scripts for SERVICES. | |
326 | (mapm %store-monad | |
327 | (cut gexp->file "activate-service" <>) | |
328 | gexps)) | |
329 | ||
fd129893 | 330 | (mlet* %store-monad ((actions (service-activations))) |
0adfe95a | 331 | (gexp->file "activate" |
232ccbef LC |
332 | (with-imported-modules (source-module-closure |
333 | '((gnu build activation))) | |
fd129893 LC |
334 | #~(begin |
335 | (use-modules (gnu build activation)) | |
0adfe95a | 336 | |
fd129893 LC |
337 | ;; Make sure /bin/sh is valid and current. |
338 | (activate-/bin/sh | |
339 | (string-append #$(canonical-package bash) "/bin/sh")) | |
0adfe95a | 340 | |
fd129893 LC |
341 | ;; Run the services' activation snippets. |
342 | ;; TODO: Use 'load-compiled'. | |
343 | (for-each primitive-load '#$actions) | |
0adfe95a | 344 | |
fd129893 LC |
345 | ;; Set up /run/current-system. |
346 | (activate-current-system)))))) | |
0adfe95a LC |
347 | |
348 | (define (gexps->activation-gexp gexps) | |
349 | "Return a gexp that runs the activation script containing GEXPS." | |
350 | (mlet %store-monad ((script (activation-script gexps))) | |
351 | (return #~(primitive-load #$script)))) | |
352 | ||
3a391e68 LC |
353 | (define (second-argument a b) b) |
354 | ||
0adfe95a LC |
355 | (define activation-service-type |
356 | (service-type (name 'activate) | |
357 | (extensions | |
358 | (list (service-extension boot-service-type | |
359 | gexps->activation-gexp))) | |
360 | (compose append) | |
361 | (extend second-argument))) | |
362 | ||
363 | (define %activation-service | |
364 | ;; The activation service produces the activation script from the gexps it | |
365 | ;; receives. | |
366 | (service activation-service-type #t)) | |
367 | ||
a241a7ac LC |
368 | (define %modprobe-wrapper |
369 | ;; Wrapper for the 'modprobe' command that knows where modules live. | |
370 | ;; | |
371 | ;; This wrapper is typically invoked by the Linux kernel ('call_modprobe', | |
372 | ;; in kernel/kmod.c), a situation where the 'LINUX_MODULE_DIRECTORY' | |
373 | ;; environment variable is not set---hence the need for this wrapper. | |
374 | (let ((modprobe "/run/current-system/profile/bin/modprobe")) | |
375 | (program-file "modprobe" | |
376 | #~(begin | |
377 | (setenv "LINUX_MODULE_DIRECTORY" | |
378 | "/run/booted-system/kernel/lib/modules") | |
379 | (apply execl #$modprobe | |
380 | (cons #$modprobe (cdr (command-line)))))))) | |
381 | ||
382 | (define %linux-kernel-activation | |
383 | ;; Activation of the Linux kernel running on the bare metal (as opposed to | |
384 | ;; running in a container.) | |
385 | #~(begin | |
386 | ;; Tell the kernel to use our 'modprobe' command. | |
387 | (activate-modprobe #$%modprobe-wrapper) | |
388 | ||
389 | ;; Let users debug their own processes! | |
390 | (activate-ptrace-attach))) | |
391 | ||
392 | (define linux-bare-metal-service-type | |
393 | (service-type (name 'linux-bare-metal) | |
394 | (extensions | |
395 | (list (service-extension activation-service-type | |
396 | (const %linux-kernel-activation)))))) | |
397 | ||
398 | (define %linux-bare-metal-service | |
399 | ;; The service that does things that are needed on the "bare metal", but not | |
400 | ;; necessary or impossible in a container. | |
401 | (service linux-bare-metal-service-type #f)) | |
402 | ||
0adfe95a LC |
403 | (define (etc-directory service) |
404 | "Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE." | |
405 | (files->etc-directory (service-parameters service))) | |
406 | ||
407 | (define (files->etc-directory files) | |
408 | (file-union "etc" files)) | |
409 | ||
d62e201c LC |
410 | (define (etc-entry files) |
411 | "Return an entry for the /etc directory consisting of FILES in the system | |
412 | directory." | |
413 | (with-monad %store-monad | |
414 | (return `(("etc" ,(files->etc-directory files)))))) | |
415 | ||
0adfe95a LC |
416 | (define etc-service-type |
417 | (service-type (name 'etc) | |
418 | (extensions | |
419 | (list | |
420 | (service-extension activation-service-type | |
421 | (lambda (files) | |
422 | (let ((etc | |
423 | (files->etc-directory files))) | |
d62e201c LC |
424 | #~(activate-etc #$etc)))) |
425 | (service-extension system-service-type etc-entry))) | |
0adfe95a LC |
426 | (compose concatenate) |
427 | (extend append))) | |
428 | ||
429 | (define (etc-service files) | |
430 | "Return a new service of ETC-SERVICE-TYPE that populates /etc with FILES. | |
431 | FILES must be a list of name/file-like object pairs." | |
432 | (service etc-service-type files)) | |
433 | ||
434 | (define setuid-program-service-type | |
435 | (service-type (name 'setuid-program) | |
436 | (extensions | |
437 | (list (service-extension activation-service-type | |
438 | (lambda (programs) | |
439 | #~(activate-setuid-programs | |
440 | (list #$@programs)))))) | |
441 | (compose concatenate) | |
442 | (extend append))) | |
443 | ||
af4c3fd5 LC |
444 | (define (packages->profile-entry packages) |
445 | "Return a system entry for the profile containing PACKAGES." | |
446 | (mlet %store-monad ((profile (profile-derivation | |
60a0886d SB |
447 | (packages->manifest |
448 | (delete-duplicates packages eq?))))) | |
af4c3fd5 LC |
449 | (return `(("profile" ,profile))))) |
450 | ||
451 | (define profile-service-type | |
452 | ;; The service that populates the system's profile---i.e., | |
453 | ;; /run/current-system/profile. It is extended by package lists. | |
454 | (service-type (name 'profile) | |
455 | (extensions | |
456 | (list (service-extension system-service-type | |
457 | packages->profile-entry))) | |
458 | (compose concatenate) | |
459 | (extend append))) | |
460 | ||
0adfe95a LC |
461 | (define (firmware->activation-gexp firmware) |
462 | "Return a gexp to make the packages listed in FIRMWARE loadable by the | |
463 | kernel." | |
464 | (let ((directory (directory-union "firmware" firmware))) | |
465 | ;; Tell the kernel where firmware is. | |
466 | #~(activate-firmware (string-append #$directory "/lib/firmware")))) | |
467 | ||
468 | (define firmware-service-type | |
469 | ;; The service that collects firmware. | |
470 | (service-type (name 'firmware) | |
471 | (extensions | |
472 | (list (service-extension activation-service-type | |
473 | firmware->activation-gexp))) | |
474 | (compose concatenate) | |
475 | (extend append))) | |
476 | ||
e0b47290 LC |
477 | (define (gc-roots->system-entry roots) |
478 | "Return an entry in the system's output containing symlinks to ROOTS." | |
479 | (mlet %store-monad ((entry (gexp->derivation | |
480 | "gc-roots" | |
481 | #~(let ((roots '#$roots)) | |
482 | (mkdir #$output) | |
483 | (chdir #$output) | |
484 | (for-each symlink | |
485 | roots | |
486 | (map number->string | |
487 | (iota (length roots)))))))) | |
488 | (return (if (null? roots) | |
489 | '() | |
490 | `(("gc-roots" ,entry)))))) | |
491 | ||
492 | (define gc-root-service-type | |
493 | ;; A service to associate extra garbage-collector roots to the system. This | |
494 | ;; is a simple hack that guarantees that the system retains references to | |
495 | ;; the given list of roots. Roots must be "lowerable" objects like | |
496 | ;; packages, or derivations. | |
497 | (service-type (name 'gc-roots) | |
498 | (extensions | |
499 | (list (service-extension system-service-type | |
500 | gc-roots->system-entry))) | |
501 | (compose concatenate) | |
502 | (extend append))) | |
503 | ||
0adfe95a LC |
504 | \f |
505 | ;;; | |
506 | ;;; Service folding. | |
507 | ;;; | |
508 | ||
509 | (define-condition-type &service-error &error | |
510 | service-error?) | |
511 | ||
512 | (define-condition-type &missing-target-service-error &service-error | |
513 | missing-target-service-error? | |
514 | (service missing-target-service-error-service) | |
515 | (target-type missing-target-service-error-target-type)) | |
516 | ||
517 | (define-condition-type &ambiguous-target-service-error &service-error | |
518 | ambiguous-target-service-error? | |
519 | (service ambiguous-target-service-error-service) | |
520 | (target-type ambiguous-target-service-error-target-type)) | |
521 | ||
522 | (define (service-back-edges services) | |
523 | "Return a procedure that, when passed a <service>, returns the list of | |
524 | <service> objects that depend on it." | |
525 | (define (add-edges service edges) | |
526 | (define (add-edge extension edges) | |
527 | (let ((target-type (service-extension-target extension))) | |
528 | (match (filter (lambda (service) | |
529 | (eq? (service-kind service) target-type)) | |
530 | services) | |
531 | ((target) | |
532 | (vhash-consq target service edges)) | |
533 | (() | |
534 | (raise | |
535 | (condition (&missing-target-service-error | |
536 | (service service) | |
537 | (target-type target-type)) | |
538 | (&message | |
539 | (message | |
540 | (format #f (_ "no target of type '~a' for service ~s") | |
541 | (service-type-name target-type) | |
542 | service)))))) | |
543 | (x | |
544 | (raise | |
545 | (condition (&ambiguous-target-service-error | |
546 | (service service) | |
547 | (target-type target-type)) | |
548 | (&message | |
549 | (message | |
550 | (format #f | |
551 | (_ "more than one target service of type '~a'") | |
552 | (service-type-name target-type)))))))))) | |
553 | ||
554 | (fold add-edge edges (service-type-extensions (service-kind service)))) | |
555 | ||
556 | (let ((edges (fold add-edges vlist-null services))) | |
557 | (lambda (node) | |
558 | (reverse (vhash-foldq* cons '() node edges))))) | |
559 | ||
d62e201c LC |
560 | (define* (fold-services services |
561 | #:key (target-type system-service-type)) | |
0adfe95a LC |
562 | "Fold SERVICES by propagating their extensions down to the root of type |
563 | TARGET-TYPE; return the root service adjusted accordingly." | |
564 | (define dependents | |
565 | (service-back-edges services)) | |
566 | ||
567 | (define (matching-extension target) | |
568 | (let ((target (service-kind target))) | |
569 | (match-lambda | |
570 | (($ <service-extension> type) | |
571 | (eq? type target))))) | |
572 | ||
573 | (define (apply-extension target) | |
574 | (lambda (service) | |
575 | (match (find (matching-extension target) | |
576 | (service-type-extensions (service-kind service))) | |
577 | (($ <service-extension> _ compute) | |
578 | (compute (service-parameters service)))))) | |
579 | ||
580 | (match (filter (lambda (service) | |
581 | (eq? (service-kind service) target-type)) | |
582 | services) | |
583 | ((sink) | |
584 | (let loop ((sink sink)) | |
585 | (let* ((dependents (map loop (dependents sink))) | |
586 | (extensions (map (apply-extension sink) dependents)) | |
587 | (extend (service-type-extend (service-kind sink))) | |
588 | (compose (service-type-compose (service-kind sink))) | |
589 | (params (service-parameters sink))) | |
590 | ;; We distinguish COMPOSE and EXTEND because PARAMS typically has a | |
591 | ;; different type than the elements of EXTENSIONS. | |
592 | (if extend | |
593 | (service (service-kind sink) | |
594 | (extend params (compose extensions))) | |
595 | sink)))) | |
596 | (() | |
597 | (raise | |
598 | (condition (&missing-target-service-error | |
599 | (service #f) | |
600 | (target-type target-type)) | |
601 | (&message | |
602 | (message (format #f (_ "service of type '~a' not found") | |
603 | (service-type-name target-type))))))) | |
604 | (x | |
605 | (raise | |
606 | (condition (&ambiguous-target-service-error | |
607 | (service #f) | |
608 | (target-type target-type)) | |
609 | (&message | |
610 | (message | |
611 | (format #f | |
612 | (_ "more than one target service of type '~a'") | |
613 | (service-type-name target-type))))))))) | |
db4fdc04 LC |
614 | |
615 | ;;; services.scm ends here. |