aboutsummaryrefslogtreecommitdiff
path: root/gnu/packages/moe.scm
diff options
context:
space:
mode:
Diffstat (limited to 'gnu/packages/moe.scm')
0 files changed, 0 insertions, 0 deletions
53'>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
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013-2016, 2018-2024 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2017 Clément Lassieur <clement@lassieur.org>
;;; Copyright © 2018 Carlo Zancanaro <carlo@zancanaro.id.au>
;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
;;;
;;; 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 services shepherd)
  #:use-module (guix ui)
  #:use-module (guix sets)
  #:use-module (guix gexp)
  #:use-module (guix store)
  #:use-module (guix records)
  #:use-module (guix packages)
  #:use-module (guix utils)
  #:use-module ((guix diagnostics)
                #:select (define-with-syntax-properties formatted-message))
  #:use-module (gnu services)
  #:use-module (gnu services herd)
  #:use-module (gnu packages admin)
  #:use-module (ice-9 match)
  #:use-module (ice-9 vlist)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:export (shepherd-configuration
            shepherd-configuration?
            shepherd-configuration-shepherd
            shepherd-configuration-services

            shepherd-root-service-type
            %shepherd-root-service
            shepherd-service-type

            shepherd-service
            shepherd-service?
            shepherd-service-documentation
            shepherd-service-provision
            shepherd-service-canonical-name
            shepherd-service-requirement
            shepherd-service-one-shot?
            shepherd-service-respawn-limit
            shepherd-service-respawn-delay
            shepherd-service-respawn?
            shepherd-service-start
            shepherd-service-stop
            shepherd-service-auto-start?
            shepherd-service-modules

            shepherd-action
            shepherd-action?
            shepherd-action-name
            shepherd-action-documentation
            shepherd-action-procedure

            shepherd-configuration-action

            %default-modules

            shepherd-service-file

            shepherd-service-lookup-procedure
            shepherd-service-back-edges
            shepherd-service-upgrade

            user-processes-service-type

            assert-valid-graph))

;;; Commentary:
;;;
;;; Instantiating system services as a shepherd configuration file.
;;;
;;; Code:


(define-record-type* <shepherd-configuration>
  shepherd-configuration make-shepherd-configuration
  shepherd-configuration?
  (shepherd shepherd-configuration-shepherd
            (default shepherd-0.10)) ; file-like
  (services shepherd-configuration-services
            (default '()))) ; list of <shepherd-service>

(define (shepherd-boot-gexp config)
  "Return a gexp starting the shepherd service."
  (let ((shepherd (shepherd-configuration-shepherd config))
        (services (shepherd-configuration-services config)))
  #~(begin
      ;; Keep track of the booted system.
      (false-if-exception (delete-file "/run/booted-system"))

      ;; Make /run/booted-system, an indirect GC root, point to the store item
      ;; /run/current-system points to.  Use 'canonicalize-path' rather than
      ;; 'readlink' to make sure we get the store item.
      (symlink (canonicalize-path "/run/current-system")
               "/run/booted-system")

      ;; Ensure open file descriptors are close-on-exec so shepherd doesn't
      ;; inherit them.
      (let loop ((fd 3))
        (when (< fd 1024)
          (false-if-exception
           (let ((flags (fcntl fd F_GETFD)))
             (when (zero? (logand flags FD_CLOEXEC))
               (fcntl fd F_SETFD (logior FD_CLOEXEC flags)))))
          (loop (+ fd 1))))

      ;; Start shepherd.
      (execl #$(file-append shepherd "/bin/shepherd")
             "shepherd" "--config"
             #$(shepherd-configuration-file services shepherd)))))

(define shepherd-packages
  (compose list shepherd-configuration-shepherd))

(define shepherd-root-service-type
  (service-type
   (name 'shepherd-root)
   ;; Extending the root shepherd service (aka. PID 1) happens by
   ;; concatenating the list of services provided by the extensions.
   (compose concatenate)
   (extend (lambda (config extra-services)
             (shepherd-configuration
               (inherit config)
               (services (append (shepherd-configuration-services config)
                                 extra-services)))))
   (extensions (list (service-extension boot-service-type
                                        shepherd-boot-gexp)
                     (service-extension profile-service-type
                                        shepherd-packages)))
   (default-value (shepherd-configuration))
   (description
    "Run the GNU Shepherd as PID 1---i.e., the operating system's first
process.  The Shepherd takes care of managing services such as daemons by
ensuring they are started and stopped in the right order.")))

(define %shepherd-root-service
  ;; The root shepherd service, aka. PID 1.  Its parameter is a
  ;; <shepherd-configuration>.
  (service shepherd-root-service-type))

(define-syntax shepherd-service-type
  (syntax-rules (description)
    "Return a <service-type> denoting a simple shepherd service--i.e., the type
for a service that extends SHEPHERD-ROOT-SERVICE-TYPE and nothing else.  When
DEFAULT is given, use it as the service's default value."
    ((_ service-name proc default (description text))
     (service-type
      (name service-name)
      (extensions
       (list (service-extension shepherd-root-service-type
                                (compose list proc))))
      (default-value default)
      (description text)))
    ((_ service-name proc (description text))
     (service-type
      (name service-name)
      (extensions
       (list (service-extension shepherd-root-service-type
                                (compose list proc))))
      (description text)))))

(define %default-imported-modules
  ;; Default set of modules imported for a service's consumption.
  '((guix build utils)
    (guix build syscalls)))

(define %default-modules
  ;; Default set of modules visible in a service's file.
  `((shepherd service)
    ((guix build utils) #:hide (delete))
    (guix build syscalls)))

(define-with-syntax-properties (validate-provision (provision properties))
  (match provision
    (((? symbol?) ..1) provision)
    (_
     (raise
      (make-compound-condition
       (condition
        (&error-location
         (location (source-properties->location properties))))
       (formatted-message
        (G_ "'provision' must be a non-empty list of symbols")))))))

(define-record-type* <shepherd-service>
  shepherd-service make-shepherd-service
  shepherd-service?
  (documentation shepherd-service-documentation        ;string
                 (default "[No documentation.]"))
  (provision     shepherd-service-provision            ;list of symbols
                 (sanitize validate-provision))
  (requirement   shepherd-service-requirement          ;list of symbols
                 (default '()))
  (one-shot?     shepherd-service-one-shot?            ;Boolean
                 (default #f))
  (respawn?      shepherd-service-respawn?             ;Boolean
                 (default #t))
  (respawn-limit shepherd-service-respawn-limit
                 (default #f))
  (respawn-delay shepherd-service-respawn-delay
                 (default #f))
  (start         shepherd-service-start)               ;g-expression (procedure)
  (stop          shepherd-service-stop                 ;g-expression (procedure)
                 (default #~(const #f)))
  (actions       shepherd-service-actions              ;list of <shepherd-action>
                 (default '()))
  (auto-start?   shepherd-service-auto-start?          ;Boolean
                 (default #t))
  (modules       shepherd-service-modules              ;list of module names
                 (default %default-modules)))

(define-record-type* <shepherd-action>
  shepherd-action make-shepherd-action
  shepherd-action?
  (name          shepherd-action-name)            ;symbol
  (procedure     shepherd-action-procedure)       ;gexp
  (documentation shepherd-action-documentation))  ;string

(define (shepherd-service-canonical-name service)
  "Return the 'canonical name' of SERVICE."
  (first (shepherd-service-provision service)))

(define (assert-valid-graph services)
  "Raise an error if SERVICES does not define a valid shepherd service graph,
for instance if a service requires a nonexistent service, or if more than one
service uses a given name.

These are constraints that shepherd's 'register-service' verifies but we'd
better verify them here statically than wait until PID 1 halts with an
assertion failure."
  (define provisions
    ;; The set of provisions (symbols).  Bail out if a symbol is given more
    ;; than once.
    (fold (lambda (service set)
            (define (assert-unique symbol)
              (when (set-contains? set symbol)
                (raise (condition
                        (&message
                         (message
                          (format #f (G_ "service '~a' provided more than once")
                                  symbol)))))))

            (for-each assert-unique (shepherd-service-provision service))
            (fold set-insert set (shepherd-service-provision service)))
          (setq 'shepherd)
          services))

  (define (assert-satisfied-requirements service)
    ;; Bail out if the requirements of SERVICE aren't satisfied.
    (for-each (lambda (requirement)
                (unless (set-contains? provisions requirement)
                  (raise (condition
                          (&message
                           (message
                            (format #f (G_ "service '~a' requires '~a', \
which is not provided by any service")
                                    (match (shepherd-service-provision service)
                                      ((head . _) head)
                                      (_          service))
                                    requirement)))))))
              (shepherd-service-requirement service)))

  (for-each assert-satisfied-requirements services))

(define %store-characters
  ;; Valid store characters; see 'checkStoreName' in the daemon.
  (string->char-set
   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+-._?="))

(define (shepherd-service-file-name service)
  "Return the file name where the initialization code for SERVICE is to be
stored."
  (let ((provisions (string-join (map symbol->string
                                      (shepherd-service-provision service)))))
    (string-append "shepherd-"
                   (string-map (lambda (chr)
                                 (if (char-set-contains? %store-characters chr)
                                     chr
                                     #\-))
                               provisions)
                   ".scm")))

(define (shepherd-service-file service)
  "Return a file defining SERVICE."
  (scheme-file (shepherd-service-file-name service)
               (with-imported-modules %default-imported-modules
                 #~(begin
                     (use-modules #$@(shepherd-service-modules service))

                     (service
                      '#$(shepherd-service-provision service)
                       #:documentation '#$(shepherd-service-documentation service)
                       #:requirement '#$(shepherd-service-requirement service)

                       ;; The 'one-shot?' slot is new in Shepherd 0.6.0.
                       ;; Older versions ignore it.
                       #:one-shot? '#$(shepherd-service-one-shot? service)

                       #:respawn? '#$(shepherd-service-respawn? service)
                       #$@(if (shepherd-service-respawn-limit service)
                              `(#:respawn-limit
                                ,(shepherd-service-respawn-limit service))
                              '())
                       #$@(if (shepherd-service-respawn-delay service)
                              `(#:respawn-delay
                                ,(shepherd-service-respawn-delay service))
                              '())
                       #:start #$(shepherd-service-start service)
                       #:stop #$(shepherd-service-stop service)
                       #:actions
                       (actions
                        #$@(map (match-lambda
                                  (($ <shepherd-action> name proc doc)
                                   #~(#$name #$doc #$proc)))
                                (shepherd-service-actions service))))))))

(define (scm->go file shepherd)
  "Compile FILE, which contains code to be loaded by shepherd's config file,
and return the resulting '.go' file. SHEPHERD is used as shepherd package."
  (define shepherd&co
    (cons shepherd
          (match (lookup-package-input shepherd "guile-fibers")
            (#f '())
            (fibers (list fibers)))))

  (let-system (system target)
    (with-extensions shepherd&co
      (computed-file (string-append (basename (scheme-file-name file) ".scm")
                                    ".go")
                     #~(begin
                         (use-modules (system base compile)
                                      (system base target))

                         ;; Do the same as the Shepherd's 'load-in-user-module'.
                         (let ((env (make-fresh-user-module)))
                           (module-use! env (resolve-interface '(shepherd service)))
                           (with-target #$(or target #~%host-type)
                             (lambda _
                               (compile-file #$file #:output-file #$output
                                             #:env env)))))

                     ;; It's faster to build locally than to download.
                     #:options '(#:local-build? #t
                                 #:substitutable? #f)))))

(define (shepherd-configuration-action file)
  "Return a 'configuration' action to display FILE, which should be the name
of the service's configuration file."
  (shepherd-action
   (name 'configuration)
   (documentation "Display the name of this service's configuration file.")
   (procedure #~(lambda (_)
                  (format #t "~a~%" #$file)
                  #$file))))

(define (shepherd-configuration-file services shepherd)
  "Return the shepherd configuration file for SERVICES.  SHEPHERD is used
as shepherd package."
  (assert-valid-graph services)

  (let ((files (map shepherd-service-file services))
        (scm->go (cute scm->go <> shepherd)))
    (define config
      #~(begin
          (use-modules (srfi srfi-34)
                       (system repl error-handling))

          (define (make-user-module)
            ;; Copied from (shepherd support), where it's private.
            (let ((m (make-fresh-user-module)))
              (module-use! m (resolve-interface '(shepherd service)))
              m))

          ;; There's code run from shepherd that uses 'call-with-input-file' &
          ;; co.--e.g., the 'urandom-seed' service.  Starting from Shepherd
          ;; 0.9.2, users need to make sure not to leak non-close-on-exec file
          ;; descriptors to child processes.  To address that, replace the
          ;; standard bindings with O_CLOEXEC variants.
          (set! call-with-input-file
                (lambda (file proc)
                  (call-with-port (open file (logior O_RDONLY O_CLOEXEC))
                    proc)))
          (set! call-with-output-file
                (lambda (file proc)
                  (call-with-port (open file (logior O_WRONLY O_CREAT O_CLOEXEC))
                    proc)))

          ;; Specify the default environment visible to all the services.
          ;; Without this statement, all the environment variables of PID 1
          ;; are inherited by child services.
          (default-environment-variables
            '("PATH=/run/current-system/profile/bin"))

          ;; Booting off a DVD, especially on a slow machine, can make
          ;; everything slow.  Thus, increase the timeout compared to the
          ;; default 5s in the Shepherd 0.7.0.  See
          ;; <https://bugs.gnu.org/40572>.
          (default-pid-file-timeout 30)

          ;; Arrange to spawn a REPL if something goes wrong.  This is better
          ;; than a kernel panic.
          (call-with-error-handling
            (lambda ()
              (register-services
               (parameterize ((current-warning-port
                               (%make-void-port "w")))
                 (map (lambda (file)
                        (save-module-excursion
                         (lambda ()
                           (set-current-module (make-user-module))
                           (load-compiled file))))
                      '#$(map scm->go files))))))

          (format #t "starting services...~%")
          (let ((services-to-start
                 '#$(append-map shepherd-service-provision
                                (filter shepherd-service-auto-start?
                                        services))))
            (start-in-the-background services-to-start)

            ;; Hang up stdin.  At this point, we assume that 'start' methods
            ;; that required user interaction on the console (e.g.,
            ;; 'cryptsetup open' invocations, post-fsck emergency REPL) have
            ;; completed.  User interaction becomes impossible after this
            ;; call; this avoids situations where services wrongfully lead
            ;; PID 1 to read from stdin (the console), which users may not
            ;; have access to (see <https://bugs.gnu.org/23697>).
            (redirect-port (open "/dev/null" (logior O_RDONLY O_CLOEXEC))
                           (current-input-port)))))

    (scheme-file "shepherd.conf" config)))

(define* (shepherd-service-lookup-procedure services
                                            #:optional
                                            (provision
                                             shepherd-service-provision))
  "Return a procedure that, when passed a symbol, return the item among
SERVICES that provides this symbol.  PROVISION must be a one-argument
procedure that takes a service and returns the list of symbols it provides."
  (let ((services (fold (lambda (service result)
                          (fold (cut vhash-consq <> service <>)
                                result
                                (provision service)))
                        vlist-null
                        services)))
    (lambda (name)
      (match (vhash-assq name services)
        ((_ . service) service)
        (#f            #f)))))

(define* (shepherd-service-back-edges services
                                      #:key
                                      (provision shepherd-service-provision)
                                      (requirement shepherd-service-requirement))
  "Return a procedure that, when given a <shepherd-service> from SERVICES,
returns the list of <shepherd-service> that depend on it.

Use PROVISION and REQUIREMENT as one-argument procedures that return the
symbols provided/required by a service."
  (define provision->service
    (shepherd-service-lookup-procedure services provision))

  (define edges
    (fold (lambda (service edges)
            (fold (lambda (requirement edges)
                    (vhash-consq (provision->service requirement) service
                                 edges))
                  edges
                  (requirement service)))
          vlist-null
          services))

  (lambda (service)
    (vhash-foldq* cons '() service edges)))

(define (shepherd-service-upgrade live target)
  "Return two values: the subset of LIVE (a list of <live-service>) that needs
to be unloaded, and the subset of TARGET (a list of <shepherd-service>) that
need to be restarted to complete their upgrade."
  (define (essential? service)
    (memq (first (live-service-provision service))
          '(root shepherd)))

  (define lookup-target
    (shepherd-service-lookup-procedure target
                                       shepherd-service-provision))

  (define lookup-live
    (shepherd-service-lookup-procedure live
                                       live-service-provision))

  (define (running? service)
    (and=> (lookup-live (shepherd-service-canonical-name service))
           live-service-running))

  (define live-service-dependents
    (shepherd-service-back-edges live
                                 #:provision live-service-provision
                                 #:requirement live-service-requirement))

  (define (obsolete? service)
    (match (lookup-target (first (live-service-provision service)))
      (#f (every obsolete? (live-service-dependents service)))
      (_  #f)))

  (define to-restart
    ;; Restart services that are currently running.
    (filter running? target))

  (define to-unload
    ;; Unload services that are no longer required.  Essential services must
    ;; be kept and transient services such as inetd child services should be
    ;; kept as well--they'll vanish eventually.
    (remove (lambda (live)
              (or (essential? live)
                  (live-service-transient? live)))
            (filter obsolete? live)))

  (values to-unload to-restart))


;;;
;;; User processes.
;;;

(define %do-not-kill-file
  ;; Name of the file listing PIDs of processes that must survive when halting
  ;; the system.  Typical example is user-space file systems.
  "/etc/shepherd/do-not-kill")

(define (user-processes-shepherd-service requirements)
  "Return the 'user-processes' Shepherd service with dependencies on
REQUIREMENTS (a list of service names).

This is a synchronization point used to make sure user processes and daemons
get started only after crucial initial services have been started---file
system mounts, etc.  This is similar to the 'sysvinit' target in systemd."
  (define grace-delay
    ;; Delay after sending SIGTERM and before sending SIGKILL.
    4)

  (list (shepherd-service
         (documentation "When stopped, terminate all user processes.")
         (provision '(user-processes))
         (requirement requirements)
         (start #~(const #t))
         (stop #~(lambda _
                   (define (kill-except omit signal)
                     ;; Kill all the processes with SIGNAL except those listed
                     ;; in OMIT and the current process.
                     (let ((omit (cons (getpid) omit)))
                       (for-each (lambda (pid)
                                   (unless (memv pid omit)
                                     (false-if-exception
                                      (kill pid signal))))
                                 (processes))))

                   (define omitted-pids
                     ;; List of PIDs that must not be killed.
                     (if (file-exists? #$%do-not-kill-file)
                         (map string->number
                              (call-with-input-file #$%do-not-kill-file
                                (compose string-tokenize
                                         (@ (ice-9 rdelim) read-string))))
                         '()))

                   (define (now)
                     (car (gettimeofday)))

                   (define (sleep* n)
                     ;; Really sleep N seconds.
                     ;; Work around <http://bugs.gnu.org/19581>.
                     (define start (now))
                     (let loop ((elapsed 0))
                       (when (> n elapsed)
                         (sleep (- n elapsed))
                         (loop (- (now) start)))))

                   (define lset= (@ (srfi srfi-1) lset=))

                   (display "sending all processes the TERM signal\n")

                   (if (null? omitted-pids)
                       (begin
                         ;; Easy: terminate all of them.
                         (kill -1 SIGTERM)
                         (sleep* #$grace-delay)
                         (kill -1 SIGKILL))
                       (begin
                         ;; Kill them all except OMITTED-PIDS.  XXX: We would
                         ;; like to (kill -1 SIGSTOP) to get a fixed list of
                         ;; processes, like 'killall5' does, but that seems
                         ;; unreliable.
                         (kill-except omitted-pids SIGTERM)
                         (sleep* #$grace-delay)
                         (kill-except omitted-pids SIGKILL)
                         (delete-file #$%do-not-kill-file)))

                   (let wait ()
                     ;; Reap children, if any, so that we don't end up with
                     ;; zombies and enter an infinite loop.
                     (let reap-children ()
                       (define result
                         (false-if-exception
                          (waitpid WAIT_ANY (if (null? omitted-pids)
                                                0
                                                WNOHANG))))

                       (when (and (pair? result)
                                  (not (zero? (car result))))
                         (reap-children)))

                     (let ((pids (processes)))
                       (unless (lset= = pids (cons 1 omitted-pids))
                         (format #t "waiting for process termination\
 (processes left: ~s)~%"
                                 pids)
                         (sleep* 2)
                         (wait))))

                   (display "all processes have been terminated\n")
                   #f))
         (respawn? #f))))

(define user-processes-service-type
  (service-type
   (name 'user-processes)
   (extensions (list (service-extension shepherd-root-service-type
                                        user-processes-shepherd-service)))
   (compose concatenate)
   (extend append)

   ;; The value is the list of Shepherd services 'user-processes' depends on.
   ;; Extensions can add new services to this list.
   (default-value '())

   (description "The @code{user-processes} service is responsible for
terminating all the processes so that the root file system can be re-mounted
read-only, just before rebooting/halting.  Processes still running after a few
seconds after @code{SIGTERM} has been sent are terminated with
@code{SIGKILL}.")))

;;; shepherd.scm ends here