* gnu/services.scm (activation-script): Move 'activation-current-system' call before (for-each primitive-load …). Signed-off-by: Ludovic Courtès <ludo@gnu.org>
		
			
				
	
	
		
			617 lines
		
	
	
	
		
			24 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
			
		
		
	
	
			617 lines
		
	
	
	
		
			24 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
| ;;; GNU Guix --- Functional package management for GNU
 | ||
| ;;; Copyright © 2015, 2016 Ludovic Courtès <ludo@gnu.org>
 | ||
| ;;; Copyright © 2016 Chris Marusich <cmmarusich@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 (gnu services)
 | ||
|   #:use-module (guix gexp)
 | ||
|   #:use-module (guix monads)
 | ||
|   #:use-module (guix store)
 | ||
|   #:use-module (guix records)
 | ||
|   #:use-module (guix profiles)
 | ||
|   #:use-module (guix sets)
 | ||
|   #:use-module (guix ui)
 | ||
|   #:use-module (guix modules)
 | ||
|   #:use-module (gnu packages base)
 | ||
|   #:use-module (gnu packages bash)
 | ||
|   #:use-module (srfi srfi-1)
 | ||
|   #:use-module (srfi srfi-9)
 | ||
|   #:use-module (srfi srfi-9 gnu)
 | ||
|   #:use-module (srfi srfi-26)
 | ||
|   #:use-module (srfi srfi-34)
 | ||
|   #:use-module (srfi srfi-35)
 | ||
|   #:use-module (ice-9 vlist)
 | ||
|   #:use-module (ice-9 match)
 | ||
|   #:export (service-extension
 | ||
|             service-extension?
 | ||
| 
 | ||
|             service-type
 | ||
|             service-type?
 | ||
|             service-type-name
 | ||
|             service-type-extensions
 | ||
|             service-type-compose
 | ||
|             service-type-extend
 | ||
| 
 | ||
|             service
 | ||
|             service?
 | ||
|             service-kind
 | ||
|             service-parameters
 | ||
| 
 | ||
|             simple-service
 | ||
|             modify-services
 | ||
|             service-back-edges
 | ||
|             fold-services
 | ||
| 
 | ||
|             service-error?
 | ||
|             missing-target-service-error?
 | ||
|             missing-target-service-error-service
 | ||
|             missing-target-service-error-target-type
 | ||
|             ambiguous-target-service-error?
 | ||
|             ambiguous-target-service-error-service
 | ||
|             ambiguous-target-service-error-target-type
 | ||
| 
 | ||
|             system-service-type
 | ||
|             boot-service-type
 | ||
|             cleanup-service-type
 | ||
|             activation-service-type
 | ||
|             activation-service->script
 | ||
|             %linux-bare-metal-service
 | ||
|             etc-service-type
 | ||
|             etc-directory
 | ||
|             setuid-program-service-type
 | ||
|             profile-service-type
 | ||
|             firmware-service-type
 | ||
|             gc-root-service-type
 | ||
| 
 | ||
|             %boot-service
 | ||
|             %activation-service
 | ||
|             etc-service
 | ||
| 
 | ||
|             file-union))                      ;XXX: for lack of a better place
 | ||
| 
 | ||
| ;;; Comment:
 | ||
| ;;;
 | ||
| ;;; This module defines a broad notion of "service types" and "services."
 | ||
| ;;;
 | ||
| ;;; A service type describe how its instances extend instances of other
 | ||
| ;;; service types.  For instance, some services extend the instance of
 | ||
| ;;; ACCOUNT-SERVICE-TYPE by providing it with accounts and groups to create;
 | ||
| ;;; others extend SHEPHERD-ROOT-SERVICE-TYPE by passing it instances of
 | ||
| ;;; <shepherd-service>.
 | ||
| ;;;
 | ||
| ;;; When applicable, the service type defines how it can itself be extended,
 | ||
| ;;; by providing one procedure to compose extensions, and one procedure to
 | ||
| ;;; extend itself.
 | ||
| ;;;
 | ||
| ;;; A notable service type is SYSTEM-SERVICE-TYPE, which has a single
 | ||
| ;;; instance, which is the root of the service DAG.  Its value is the
 | ||
| ;;; derivation that produces the 'system' directory as returned by
 | ||
| ;;; 'operating-system-derivation'.
 | ||
| ;;;
 | ||
| ;;; The 'fold-services' procedure can be passed a list of procedures, which it
 | ||
| ;;; "folds" by propagating extensions down the graph; it returns the root
 | ||
| ;;; service after the applying all its extensions.
 | ||
| ;;;
 | ||
| ;;; Code:
 | ||
| 
 | ||
| (define-record-type <service-extension>
 | ||
|   (service-extension target compute)
 | ||
|   service-extension?
 | ||
|   (target  service-extension-target)              ;<service-type>
 | ||
|   (compute service-extension-compute))            ;params -> params
 | ||
| 
 | ||
| (define-record-type* <service-type> service-type make-service-type
 | ||
|   service-type?
 | ||
|   (name       service-type-name)                  ;symbol (for debugging)
 | ||
| 
 | ||
|   ;; Things extended by services of this type.
 | ||
|   (extensions service-type-extensions)            ;list of <service-extensions>
 | ||
| 
 | ||
|   ;; Given a list of extensions, "compose" them.
 | ||
|   (compose    service-type-compose                ;list of Any -> Any
 | ||
|               (default #f))
 | ||
| 
 | ||
|   ;; Extend the services' own parameters with the extension composition.
 | ||
|   (extend     service-type-extend                 ;list of Any -> parameters
 | ||
|               (default #f)))
 | ||
| 
 | ||
| (define (write-service-type type port)
 | ||
|   (format port "#<service-type ~a ~a>"
 | ||
|           (service-type-name type)
 | ||
|           (number->string (object-address type) 16)))
 | ||
| 
 | ||
| (set-record-type-printer! <service-type> write-service-type)
 | ||
| 
 | ||
| ;; Services of a given type.
 | ||
| (define-record-type <service>
 | ||
|   (service type parameters)
 | ||
|   service?
 | ||
|   (type       service-kind)
 | ||
|   (parameters service-parameters))
 | ||
| 
 | ||
| (define (simple-service name target value)
 | ||
|   "Return a service that extends TARGET with VALUE.  This works by creating a
 | ||
| singleton service type NAME, of which the returned service is an instance."
 | ||
|   (let* ((extension (service-extension target identity))
 | ||
|          (type      (service-type (name name)
 | ||
|                                   (extensions (list extension)))))
 | ||
|     (service type value)))
 | ||
| 
 | ||
| (define-syntax %modify-service
 | ||
|   (syntax-rules (=>)
 | ||
|     ((_ service)
 | ||
|      service)
 | ||
|     ((_ svc (kind param => exp ...) clauses ...)
 | ||
|      (if (eq? (service-kind svc) kind)
 | ||
|          (let ((param (service-parameters svc)))
 | ||
|            (service (service-kind svc)
 | ||
|                     (begin exp ...)))
 | ||
|          (%modify-service svc clauses ...)))))
 | ||
| 
 | ||
| (define-syntax modify-services
 | ||
|   (syntax-rules ()
 | ||
|     "Modify the services listed in SERVICES according to CLAUSES and return
 | ||
| the resulting list of services.  Each clause must have the form:
 | ||
| 
 | ||
|   (TYPE VARIABLE => BODY)
 | ||
| 
 | ||
| where TYPE is a service type, such as 'guix-service-type', and VARIABLE is an
 | ||
| identifier that is bound within BODY to the value of the service of that
 | ||
| TYPE.  Consider this example:
 | ||
| 
 | ||
|   (modify-services %base-services
 | ||
|     (guix-service-type config =>
 | ||
|                        (guix-configuration
 | ||
|                         (inherit config)
 | ||
|                         (use-substitutes? #f)
 | ||
|                         (extra-options '(\"--gc-keep-derivations\"))))
 | ||
|     (mingetty-service-type config =>
 | ||
|                            (mingetty-configuration
 | ||
|                             (inherit config)
 | ||
|                             (motd (plain-file \"motd\" \"Hi there!\")))))
 | ||
| 
 | ||
| It changes the configuration of the GUIX-SERVICE-TYPE instance, and that of
 | ||
| all the MINGETTY-SERVICE-TYPE instances.
 | ||
| 
 | ||
| This is a shorthand for (map (lambda (svc) ...) %base-services)."
 | ||
|     ((_ services clauses ...)
 | ||
|      (map (lambda (service)
 | ||
|             (%modify-service service clauses ...))
 | ||
|           services))))
 | ||
| 
 | ||
| 
 | ||
| ;;;
 | ||
| ;;; Core services.
 | ||
| ;;;
 | ||
| 
 | ||
| (define (system-derivation mentries mextensions)
 | ||
|   "Return as a monadic value the derivation of the 'system' directory
 | ||
| containing the given entries."
 | ||
|   (mlet %store-monad ((entries    mentries)
 | ||
|                       (extensions (sequence %store-monad mextensions)))
 | ||
|     (lower-object
 | ||
|      (file-union "system"
 | ||
|                  (append entries (concatenate extensions))))))
 | ||
| 
 | ||
| (define system-service-type
 | ||
|   ;; This is the ultimate service type, the root of the service DAG.  The
 | ||
|   ;; service of this type is extended by monadic name/item pairs.  These items
 | ||
|   ;; end up in the "system directory" as returned by
 | ||
|   ;; 'operating-system-derivation'.
 | ||
|   (service-type (name 'system)
 | ||
|                 (extensions '())
 | ||
|                 (compose identity)
 | ||
|                 (extend system-derivation)))
 | ||
| 
 | ||
| (define (compute-boot-script _ mexps)
 | ||
|   (mlet %store-monad ((gexps (sequence %store-monad mexps)))
 | ||
|     (gexp->file "boot"
 | ||
|                 ;; Clean up and activate the system, then spawn shepherd.
 | ||
|                 #~(begin #$@gexps))))
 | ||
| 
 | ||
| (define (boot-script-entry mboot)
 | ||
|   "Return, as a monadic value, an entry for the boot script in the system
 | ||
| directory."
 | ||
|   (mlet %store-monad ((boot mboot))
 | ||
|     (return `(("boot" ,boot)))))
 | ||
| 
 | ||
| (define boot-service-type
 | ||
|   ;; The service of this type is extended by being passed gexps as monadic
 | ||
|   ;; values.  It aggregates them in a single script, as a monadic value, which
 | ||
|   ;; becomes its 'parameters'.  It is the only service that extends nothing.
 | ||
|   (service-type (name 'boot)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension system-service-type
 | ||
|                                           boot-script-entry)))
 | ||
|                 (compose append)
 | ||
|                 (extend compute-boot-script)))
 | ||
| 
 | ||
| (define %boot-service
 | ||
|   ;; The service that produces the boot script.
 | ||
|   (service boot-service-type #t))
 | ||
| 
 | ||
| (define (cleanup-gexp _)
 | ||
|   "Return as a monadic value a gexp to clean up /tmp and similar places upon
 | ||
| boot."
 | ||
|   (with-monad %store-monad
 | ||
|     (with-imported-modules '((guix build utils))
 | ||
|       (return #~(begin
 | ||
|                   (use-modules (guix build utils))
 | ||
| 
 | ||
|                   ;; Clean out /tmp and /var/run.
 | ||
|                   ;;
 | ||
|                   ;; XXX This needs to happen before service activations, so it
 | ||
|                   ;; has to be here, but this also implicitly assumes that /tmp
 | ||
|                   ;; and /var/run are on the root partition.
 | ||
|                   (letrec-syntax ((fail-safe (syntax-rules ()
 | ||
|                                                ((_ exp rest ...)
 | ||
|                                                 (begin
 | ||
|                                                   (catch 'system-error
 | ||
|                                                     (lambda () exp)
 | ||
|                                                     (const #f))
 | ||
|                                                   (fail-safe rest ...)))
 | ||
|                                                ((_)
 | ||
|                                                 #t))))
 | ||
|                     ;; Ignore I/O errors so the system can boot.
 | ||
|                     (fail-safe
 | ||
|                      (delete-file-recursively "/tmp")
 | ||
|                      (delete-file-recursively "/var/run")
 | ||
|                      (mkdir "/tmp")
 | ||
|                      (chmod "/tmp" #o1777)
 | ||
|                      (mkdir "/var/run")
 | ||
|                      (chmod "/var/run" #o755))))))))
 | ||
| 
 | ||
| (define cleanup-service-type
 | ||
|   ;; Service that cleans things up in /tmp and similar.
 | ||
|   (service-type (name 'cleanup)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension boot-service-type
 | ||
|                                           cleanup-gexp)))))
 | ||
| 
 | ||
| (define* (file-union name files)                  ;FIXME: Factorize.
 | ||
|   "Return a <computed-file> that builds a directory containing all of FILES.
 | ||
| Each item in FILES must be a list where the first element is the file name to
 | ||
| use in the new directory, and the second element is a gexp denoting the target
 | ||
| file."
 | ||
|   (computed-file name
 | ||
|                  #~(begin
 | ||
|                      (mkdir #$output)
 | ||
|                      (chdir #$output)
 | ||
|                      #$@(map (match-lambda
 | ||
|                                ((target source)
 | ||
|                                 #~(begin
 | ||
|                                     ;; Stat the source to abort early if it
 | ||
|                                     ;; does not exist.
 | ||
|                                     (stat #$source)
 | ||
| 
 | ||
|                                     (symlink #$source #$target))))
 | ||
|                              files))))
 | ||
| 
 | ||
| (define (directory-union name things)
 | ||
|   "Return a directory that is the union of THINGS."
 | ||
|   (match things
 | ||
|     ((one)
 | ||
|      ;; Only one thing; return it.
 | ||
|      one)
 | ||
|     (_
 | ||
|      (computed-file name
 | ||
|                     (with-imported-modules '((guix build union))
 | ||
|                       #~(begin
 | ||
|                           (use-modules (guix build union))
 | ||
|                           (union-build #$output '#$things)))))))
 | ||
| 
 | ||
| (define* (activation-service->script service)
 | ||
|   "Return as a monadic value the activation script for SERVICE, a service of
 | ||
| ACTIVATION-SCRIPT-TYPE."
 | ||
|   (activation-script (service-parameters service)))
 | ||
| 
 | ||
| (define (activation-script gexps)
 | ||
|   "Return the system's activation script, which evaluates GEXPS."
 | ||
|   (define (service-activations)
 | ||
|     ;; Return the activation scripts for SERVICES.
 | ||
|     (mapm %store-monad
 | ||
|           (cut gexp->file "activate-service" <>)
 | ||
|           gexps))
 | ||
| 
 | ||
|   (mlet* %store-monad ((actions (service-activations)))
 | ||
|     (gexp->file "activate"
 | ||
|                 (with-imported-modules (source-module-closure
 | ||
|                                         '((gnu build activation)))
 | ||
|                   #~(begin
 | ||
|                       (use-modules (gnu build activation))
 | ||
| 
 | ||
|                       ;; Make sure /bin/sh is valid and current.
 | ||
|                       (activate-/bin/sh
 | ||
|                        (string-append #$(canonical-package bash) "/bin/sh"))
 | ||
| 
 | ||
|                       ;; Set up /run/current-system.  Among other things this
 | ||
|                       ;; sets up locales, which the activation snippets
 | ||
|                       ;; executed below may expect.
 | ||
|                       (activate-current-system)
 | ||
| 
 | ||
|                       ;; Run the services' activation snippets.
 | ||
|                       ;; TODO: Use 'load-compiled'.
 | ||
|                       (for-each primitive-load '#$actions))))))
 | ||
| 
 | ||
| (define (gexps->activation-gexp gexps)
 | ||
|   "Return a gexp that runs the activation script containing GEXPS."
 | ||
|   (mlet %store-monad ((script (activation-script gexps)))
 | ||
|     (return #~(primitive-load #$script))))
 | ||
| 
 | ||
| (define (second-argument a b) b)
 | ||
| 
 | ||
| (define activation-service-type
 | ||
|   (service-type (name 'activate)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension boot-service-type
 | ||
|                                           gexps->activation-gexp)))
 | ||
|                 (compose append)
 | ||
|                 (extend second-argument)))
 | ||
| 
 | ||
| (define %activation-service
 | ||
|   ;; The activation service produces the activation script from the gexps it
 | ||
|   ;; receives.
 | ||
|   (service activation-service-type #t))
 | ||
| 
 | ||
| (define %modprobe-wrapper
 | ||
|   ;; Wrapper for the 'modprobe' command that knows where modules live.
 | ||
|   ;;
 | ||
|   ;; This wrapper is typically invoked by the Linux kernel ('call_modprobe',
 | ||
|   ;; in kernel/kmod.c), a situation where the 'LINUX_MODULE_DIRECTORY'
 | ||
|   ;; environment variable is not set---hence the need for this wrapper.
 | ||
|   (let ((modprobe "/run/current-system/profile/bin/modprobe"))
 | ||
|     (program-file "modprobe"
 | ||
|                   #~(begin
 | ||
|                       (setenv "LINUX_MODULE_DIRECTORY"
 | ||
|                               "/run/booted-system/kernel/lib/modules")
 | ||
|                       (apply execl #$modprobe
 | ||
|                              (cons #$modprobe (cdr (command-line))))))))
 | ||
| 
 | ||
| (define %linux-kernel-activation
 | ||
|   ;; Activation of the Linux kernel running on the bare metal (as opposed to
 | ||
|   ;; running in a container.)
 | ||
|   #~(begin
 | ||
|       ;; Tell the kernel to use our 'modprobe' command.
 | ||
|       (activate-modprobe #$%modprobe-wrapper)
 | ||
| 
 | ||
|       ;; Let users debug their own processes!
 | ||
|       (activate-ptrace-attach)))
 | ||
| 
 | ||
| (define linux-bare-metal-service-type
 | ||
|   (service-type (name 'linux-bare-metal)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension activation-service-type
 | ||
|                                           (const %linux-kernel-activation))))))
 | ||
| 
 | ||
| (define %linux-bare-metal-service
 | ||
|   ;; The service that does things that are needed on the "bare metal", but not
 | ||
|   ;; necessary or impossible in a container.
 | ||
|   (service linux-bare-metal-service-type #f))
 | ||
| 
 | ||
| (define (etc-directory service)
 | ||
|   "Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE."
 | ||
|   (files->etc-directory (service-parameters service)))
 | ||
| 
 | ||
| (define (files->etc-directory files)
 | ||
|   (file-union "etc" files))
 | ||
| 
 | ||
| (define (etc-entry files)
 | ||
|   "Return an entry for the /etc directory consisting of FILES in the system
 | ||
| directory."
 | ||
|   (with-monad %store-monad
 | ||
|     (return `(("etc" ,(files->etc-directory files))))))
 | ||
| 
 | ||
| (define etc-service-type
 | ||
|   (service-type (name 'etc)
 | ||
|                 (extensions
 | ||
|                  (list
 | ||
|                   (service-extension activation-service-type
 | ||
|                                      (lambda (files)
 | ||
|                                        (let ((etc
 | ||
|                                               (files->etc-directory files)))
 | ||
|                                          #~(activate-etc #$etc))))
 | ||
|                   (service-extension system-service-type etc-entry)))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)))
 | ||
| 
 | ||
| (define (etc-service files)
 | ||
|   "Return a new service of ETC-SERVICE-TYPE that populates /etc with FILES.
 | ||
| FILES must be a list of name/file-like object pairs."
 | ||
|   (service etc-service-type files))
 | ||
| 
 | ||
| (define setuid-program-service-type
 | ||
|   (service-type (name 'setuid-program)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension activation-service-type
 | ||
|                                           (lambda (programs)
 | ||
|                                             #~(activate-setuid-programs
 | ||
|                                                (list #$@programs))))))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)))
 | ||
| 
 | ||
| (define (packages->profile-entry packages)
 | ||
|   "Return a system entry for the profile containing PACKAGES."
 | ||
|   (mlet %store-monad ((profile (profile-derivation
 | ||
|                                 (packages->manifest
 | ||
|                                  (delete-duplicates packages eq?)))))
 | ||
|     (return `(("profile" ,profile)))))
 | ||
| 
 | ||
| (define profile-service-type
 | ||
|   ;; The service that populates the system's profile---i.e.,
 | ||
|   ;; /run/current-system/profile.  It is extended by package lists.
 | ||
|   (service-type (name 'profile)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension system-service-type
 | ||
|                                           packages->profile-entry)))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)))
 | ||
| 
 | ||
| (define (firmware->activation-gexp firmware)
 | ||
|   "Return a gexp to make the packages listed in FIRMWARE loadable by the
 | ||
| kernel."
 | ||
|   (let ((directory (directory-union "firmware" firmware)))
 | ||
|     ;; Tell the kernel where firmware is.
 | ||
|     #~(activate-firmware (string-append #$directory "/lib/firmware"))))
 | ||
| 
 | ||
| (define firmware-service-type
 | ||
|   ;; The service that collects firmware.
 | ||
|   (service-type (name 'firmware)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension activation-service-type
 | ||
|                                           firmware->activation-gexp)))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)))
 | ||
| 
 | ||
| (define (gc-roots->system-entry roots)
 | ||
|   "Return an entry in the system's output containing symlinks to ROOTS."
 | ||
|   (mlet %store-monad ((entry (gexp->derivation
 | ||
|                               "gc-roots"
 | ||
|                               #~(let ((roots '#$roots))
 | ||
|                                   (mkdir #$output)
 | ||
|                                   (chdir #$output)
 | ||
|                                   (for-each symlink
 | ||
|                                             roots
 | ||
|                                             (map number->string
 | ||
|                                                  (iota (length roots))))))))
 | ||
|     (return (if (null? roots)
 | ||
|                 '()
 | ||
|                 `(("gc-roots" ,entry))))))
 | ||
| 
 | ||
| (define gc-root-service-type
 | ||
|   ;; A service to associate extra garbage-collector roots to the system.  This
 | ||
|   ;; is a simple hack that guarantees that the system retains references to
 | ||
|   ;; the given list of roots.  Roots must be "lowerable" objects like
 | ||
|   ;; packages, or derivations.
 | ||
|   (service-type (name 'gc-roots)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension system-service-type
 | ||
|                                           gc-roots->system-entry)))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)))
 | ||
| 
 | ||
| 
 | ||
| ;;;
 | ||
| ;;; Service folding.
 | ||
| ;;;
 | ||
| 
 | ||
| (define-condition-type &service-error &error
 | ||
|   service-error?)
 | ||
| 
 | ||
| (define-condition-type &missing-target-service-error &service-error
 | ||
|   missing-target-service-error?
 | ||
|   (service      missing-target-service-error-service)
 | ||
|   (target-type  missing-target-service-error-target-type))
 | ||
| 
 | ||
| (define-condition-type &ambiguous-target-service-error &service-error
 | ||
|   ambiguous-target-service-error?
 | ||
|   (service      ambiguous-target-service-error-service)
 | ||
|   (target-type  ambiguous-target-service-error-target-type))
 | ||
| 
 | ||
| (define (service-back-edges services)
 | ||
|   "Return a procedure that, when passed a <service>, returns the list of
 | ||
| <service> objects that depend on it."
 | ||
|   (define (add-edges service edges)
 | ||
|     (define (add-edge extension edges)
 | ||
|       (let ((target-type (service-extension-target extension)))
 | ||
|         (match (filter (lambda (service)
 | ||
|                          (eq? (service-kind service) target-type))
 | ||
|                        services)
 | ||
|           ((target)
 | ||
|            (vhash-consq target service edges))
 | ||
|           (()
 | ||
|            (raise
 | ||
|             (condition (&missing-target-service-error
 | ||
|                         (service service)
 | ||
|                         (target-type target-type))
 | ||
|                        (&message
 | ||
|                         (message
 | ||
|                          (format #f (_ "no target of type '~a' for service ~s")
 | ||
|                                  (service-type-name target-type)
 | ||
|                                  service))))))
 | ||
|           (x
 | ||
|            (raise
 | ||
|             (condition (&ambiguous-target-service-error
 | ||
|                         (service service)
 | ||
|                         (target-type target-type))
 | ||
|                        (&message
 | ||
|                         (message
 | ||
|                          (format #f
 | ||
|                                  (_ "more than one target service of type '~a'")
 | ||
|                                  (service-type-name target-type))))))))))
 | ||
| 
 | ||
|     (fold add-edge edges (service-type-extensions (service-kind service))))
 | ||
| 
 | ||
|   (let ((edges (fold add-edges vlist-null services)))
 | ||
|     (lambda (node)
 | ||
|       (reverse (vhash-foldq* cons '() node edges)))))
 | ||
| 
 | ||
| (define* (fold-services services
 | ||
|                         #:key (target-type system-service-type))
 | ||
|   "Fold SERVICES by propagating their extensions down to the root of type
 | ||
| TARGET-TYPE; return the root service adjusted accordingly."
 | ||
|   (define dependents
 | ||
|     (service-back-edges services))
 | ||
| 
 | ||
|   (define (matching-extension target)
 | ||
|     (let ((target (service-kind target)))
 | ||
|       (match-lambda
 | ||
|         (($ <service-extension> type)
 | ||
|          (eq? type target)))))
 | ||
| 
 | ||
|   (define (apply-extension target)
 | ||
|     (lambda (service)
 | ||
|       (match (find (matching-extension target)
 | ||
|                    (service-type-extensions (service-kind service)))
 | ||
|         (($ <service-extension> _ compute)
 | ||
|          (compute (service-parameters service))))))
 | ||
| 
 | ||
|   (match (filter (lambda (service)
 | ||
|                    (eq? (service-kind service) target-type))
 | ||
|                  services)
 | ||
|     ((sink)
 | ||
|      (let loop ((sink sink))
 | ||
|        (let* ((dependents (map loop (dependents sink)))
 | ||
|               (extensions (map (apply-extension sink) dependents))
 | ||
|               (extend     (service-type-extend (service-kind sink)))
 | ||
|               (compose    (service-type-compose (service-kind sink)))
 | ||
|               (params     (service-parameters sink)))
 | ||
|          ;; We distinguish COMPOSE and EXTEND because PARAMS typically has a
 | ||
|          ;; different type than the elements of EXTENSIONS.
 | ||
|          (if extend
 | ||
|              (service (service-kind sink)
 | ||
|                       (extend params (compose extensions)))
 | ||
|              sink))))
 | ||
|     (()
 | ||
|      (raise
 | ||
|       (condition (&missing-target-service-error
 | ||
|                   (service #f)
 | ||
|                   (target-type target-type))
 | ||
|                  (&message
 | ||
|                   (message (format #f (_ "service of type '~a' not found")
 | ||
|                                    (service-type-name target-type)))))))
 | ||
|     (x
 | ||
|      (raise
 | ||
|       (condition (&ambiguous-target-service-error
 | ||
|                   (service #f)
 | ||
|                   (target-type target-type))
 | ||
|                  (&message
 | ||
|                   (message
 | ||
|                    (format #f
 | ||
|                            (_ "more than one target service of type '~a'")
 | ||
|                            (service-type-name target-type)))))))))
 | ||
| 
 | ||
| ;;; services.scm ends here.
 |