Previously, build-time metadata from (guix config) would be ignored when
available--e.g., when running /run/current-system/profile/bin/guix.
This is a followup to 316fc2acbb.
* gnu/services.scm (provenance-entry): Use 'current-channels' instead of
'current-profile' + 'profile-channels'.
		
	
			
		
			
				
	
	
		
			1177 lines
		
	
	
	
		
			47 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
			
		
		
	
	
			1177 lines
		
	
	
	
		
			47 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
| ;;; GNU Guix --- Functional package management for GNU
 | ||
| ;;; Copyright © 2015-2022 Ludovic Courtès <ludo@gnu.org>
 | ||
| ;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
 | ||
| ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 | ||
| ;;; Copyright © 2020, 2021 Ricardo Wurmus <rekado@elephly.net>
 | ||
| ;;; Copyright © 2021 raid5atemyhomework <raid5atemyhomework@protonmail.com>
 | ||
| ;;; Copyright © 2020 Christine Lemmer-Webber <cwebber@dustycloud.org>
 | ||
| ;;; Copyright © 2020, 2021 Brice Waegeneire <brice@waegenei.re>
 | ||
| ;;;
 | ||
| ;;; 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)
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|   #:use-module (guix monads)
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|   #:use-module (guix store)
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|   #:use-module (guix records)
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|   #:use-module (guix profiles)
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|   #:use-module (guix discovery)
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|   #:use-module (guix combinators)
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|   #:use-module (guix channels)
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|   #:use-module (guix describe)
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|   #:use-module (guix sets)
 | ||
|   #:use-module (guix ui)
 | ||
|   #:use-module (guix diagnostics)
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|   #:autoload   (guix openpgp) (openpgp-format-fingerprint)
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|   #:use-module (guix modules)
 | ||
|   #:use-module (guix packages)
 | ||
|   #:use-module (guix utils)
 | ||
|   #:use-module (gnu packages base)
 | ||
|   #:use-module (gnu packages bash)
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|   #:use-module (gnu packages hurd)
 | ||
|   #:use-module (gnu system setuid)
 | ||
|   #:use-module (srfi srfi-1)
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|   #:use-module (srfi srfi-9)
 | ||
|   #:use-module (srfi srfi-9 gnu)
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|   #:use-module (srfi srfi-26)
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|   #:use-module (srfi srfi-34)
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|   #:use-module (srfi srfi-35)
 | ||
|   #:use-module (ice-9 vlist)
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|   #:use-module (ice-9 match)
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|   #:autoload   (ice-9 pretty-print) (pretty-print)
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|   #:export (service-extension
 | ||
|             service-extension?
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|             service-extension-target
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|             service-extension-compute
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| 
 | ||
|             service-type
 | ||
|             service-type?
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|             service-type-name
 | ||
|             service-type-extensions
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|             service-type-compose
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|             service-type-extend
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|             service-type-default-value
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|             service-type-description
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|             service-type-location
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| 
 | ||
|             %service-type-path
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|             fold-service-types
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|             lookup-service-types
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| 
 | ||
|             service
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|             service?
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|             service-kind
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|             service-value
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|             service-parameters                    ;deprecated
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| 
 | ||
|             simple-service
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|             modify-services
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|             service-back-edges
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|             instantiate-missing-services
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|             fold-services
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| 
 | ||
|             service-error?
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|             missing-value-service-error?
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|             missing-value-service-error-type
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|             missing-value-service-error-location
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|             missing-target-service-error?
 | ||
|             missing-target-service-error-service
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|             missing-target-service-error-target-type
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|             ambiguous-target-service-error?
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|             ambiguous-target-service-error-service
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|             ambiguous-target-service-error-target-type
 | ||
| 
 | ||
|             system-service-type
 | ||
|             provenance-service-type
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|             sexp->system-provenance
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|             system-provenance
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|             boot-service-type
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|             cleanup-service-type
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|             activation-service-type
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|             activation-service->script
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|             %linux-bare-metal-service
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|             %hurd-rc-script
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|             %hurd-startup-service
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|             special-files-service-type
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|             extra-special-file
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|             etc-service-type
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|             etc-directory
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|             setuid-program-service-type
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|             profile-service-type
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|             firmware-service-type
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|             gc-root-service-type
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|             linux-builder-service-type
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|             linux-builder-configuration
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|             linux-builder-configuration?
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|             linux-builder-configuration-kernel
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|             linux-builder-configuration-modules
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|             linux-loadable-module-service-type
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| 
 | ||
|             %boot-service
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|             %activation-service
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|             etc-service)
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|   #:re-export (;; Note: Re-export 'delete' to allow for proper syntax matching
 | ||
|                ;; in 'modify-services' forms.  See
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|                ;; <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=26805#16>.
 | ||
|                delete))
 | ||
| 
 | ||
| ;;; Comment:
 | ||
| ;;;
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| ;;; This module defines a broad notion of "service types" and "services."
 | ||
| ;;;
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| ;;; A service type describe how its instances extend instances of other
 | ||
| ;;; service types.  For instance, some services extend the instance of
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| ;;; ACCOUNT-SERVICE-TYPE by providing it with accounts and groups to create;
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| ;;; others extend SHEPHERD-ROOT-SERVICE-TYPE by passing it instances of
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| ;;; <shepherd-service>.
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| ;;;
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| ;;; When applicable, the service type defines how it can itself be extended,
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| ;;; by providing one procedure to compose extensions, and one procedure to
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| ;;; extend itself.
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| ;;;
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| ;;; A notable service type is SYSTEM-SERVICE-TYPE, which has a single
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| ;;; instance, which is the root of the service DAG.  Its value is the
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| ;;; derivation that produces the 'system' directory as returned by
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| ;;; 'operating-system-derivation'.
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| ;;;
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| ;;; The 'fold-services' procedure can be passed a list of procedures, which it
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| ;;; "folds" by propagating extensions down the graph; it returns the root
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| ;;; service after the applying all its extensions.
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| ;;;
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| ;;; Code:
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| 
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| (define-record-type <service-extension>
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|   (service-extension target compute)
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|   service-extension?
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|   (target  service-extension-target)              ;<service-type>
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|   (compute service-extension-compute))            ;params -> params
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| 
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| (define &no-default-value
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|   ;; Value used to denote service types that have no associated default value.
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|   '(no default value))
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| 
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| (define-record-type* <service-type> service-type make-service-type
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|   service-type?
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|   (name       service-type-name)                  ;symbol (for debugging)
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| 
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|   ;; Things extended by services of this type.
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|   (extensions service-type-extensions)            ;list of <service-extensions>
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| 
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|   ;; Given a list of extensions, "compose" them.
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|   (compose    service-type-compose                ;list of Any -> Any
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|               (default #f))
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| 
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|   ;; Extend the services' own parameters with the extension composition.
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|   (extend     service-type-extend                 ;list of Any -> parameters
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|               (default #f))
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| 
 | ||
|   ;; Optional default value for instances of this type.
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|   (default-value service-type-default-value       ;Any
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|                  (default &no-default-value))
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| 
 | ||
|   ;; Meta-data.
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|   (description  service-type-description)         ;string
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|   (location     service-type-location             ;<location>
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|                 (default (and=> (current-source-location)
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|                                 source-properties->location))
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|                 (innate)))
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| 
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| (define (write-service-type type port)
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|   (format port "#<service-type ~a ~a>"
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|           (service-type-name type)
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|           (number->string (object-address type) 16)))
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| 
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| (set-record-type-printer! <service-type> write-service-type)
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| 
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| (define %distro-root-directory
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|   ;; Absolute file name of the module hierarchy.
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|   (dirname (search-path %load-path "guix.scm")))
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| 
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| (define %service-type-path
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|   ;; Search path for service types.
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|   (make-parameter `((,%distro-root-directory . "gnu/services")
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|                     (,%distro-root-directory . "gnu/system"))))
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| 
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| (define (all-service-modules)
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|   "Return the default set of service modules."
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|   (cons (resolve-interface '(gnu services))
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|         (all-modules (%service-type-path)
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|                      #:warn warn-about-load-error)))
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| 
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| (define* (fold-service-types proc seed
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|                              #:optional
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|                              (modules (all-service-modules)))
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|   "For each service type exported by one of MODULES, call (PROC RESULT).  SEED
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| is used as the initial value of RESULT."
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|   (fold-module-public-variables (lambda (object result)
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|                                   (if (service-type? object)
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|                                       (proc object result)
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|                                       result))
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|                                 seed
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|                                 modules))
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| 
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| (define lookup-service-types
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|   (let ((table
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|          (delay (fold-service-types (lambda (type result)
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|                                       (vhash-consq (service-type-name type)
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|                                                    type result))
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|                                     vlist-null))))
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|     (lambda (name)
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|       "Return the list of services with the given NAME (a symbol)."
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|       (vhash-foldq* cons '() name (force table)))))
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| 
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| ;; Services of a given type.
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| (define-record-type <service>
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|   (make-service type value)
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|   service?
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|   (type       service-kind)
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|   (value      service-value))
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| 
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| (define-syntax service
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|   (syntax-rules ()
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|     "Return a service instance of TYPE.  The service value is VALUE or, if
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| omitted, TYPE's default value."
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|     ((_ type value)
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|      (make-service type value))
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|     ((_ type)
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|      (%service-with-default-value (current-source-location)
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|                                   type))))
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| 
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| (define (%service-with-default-value location type)
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|   "Return a instance of service type TYPE with its default value, if any.  If
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| TYPE does not have a default value, an error is raised."
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|   ;; TODO: Currently this is a run-time error but with a little bit macrology
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|   ;; we could turn it into an expansion-time error.
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|   (let ((default (service-type-default-value type)))
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|     (if (eq? default &no-default-value)
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|         (let ((location (source-properties->location location)))
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|           (raise
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|            (make-compound-condition
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|             (condition
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|              (&missing-value-service-error (type type) (location location)))
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|             (formatted-message (G_ "~a: no value specified \
 | ||
| for service of type '~a'")
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|                                (location->string location)
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|                                (service-type-name type)))))
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|         (service type default))))
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| 
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| (define-condition-type &service-error &error
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|   service-error?)
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| 
 | ||
| (define-condition-type &missing-value-service-error &service-error
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|   missing-value-service-error?
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|   (type     missing-value-service-error-type)
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|   (location missing-value-service-error-location))
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| 
 | ||
| 
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| 
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| ;;;
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| ;;; Helpers.
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| ;;;
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| 
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| (define service-parameters
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|   ;; Deprecated alias.
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|   service-value)
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| 
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| (define (simple-service name target value)
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|   "Return a service that extends TARGET with VALUE.  This works by creating a
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| singleton service type NAME, of which the returned service is an instance."
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|   (let* ((extension (service-extension target identity))
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|          (type      (service-type (name name)
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|                                   (extensions (list extension))
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|                                   (description "This is a simple service."))))
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|     (service type value)))
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| 
 | ||
| (define-syntax %modify-service
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|   (syntax-rules (=> delete)
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|     ((_ svc (delete kind) clauses ...)
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|      (if (eq? (service-kind svc) kind)
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|          #f
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|          (%modify-service svc clauses ...)))
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|     ((_ service)
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|      service)
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|     ((_ svc (kind param => exp ...) clauses ...)
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|      (if (eq? (service-kind svc) kind)
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|          (let ((param (service-value svc)))
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|            (service (service-kind svc)
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|                     (begin exp ...)))
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|          (%modify-service svc clauses ...)))))
 | ||
| 
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| (define-syntax modify-services
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|   (syntax-rules ()
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|     "Modify the services listed in SERVICES according to CLAUSES and return
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| the resulting list of services.  Each clause must have the form:
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| 
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|   (TYPE VARIABLE => BODY)
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| 
 | ||
| where TYPE is a service type, such as 'guix-service-type', and VARIABLE is an
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| identifier that is bound within BODY to the value of the service of that
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| TYPE.
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| 
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| Clauses can also remove services of a given type:
 | ||
| 
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|   (delete TYPE)
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| 
 | ||
| Consider this example:
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| 
 | ||
|   (modify-services %base-services
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|     (guix-service-type config =>
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|                        (guix-configuration
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|                         (inherit config)
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|                         (use-substitutes? #f)
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|                         (extra-options '(\"--gc-keep-derivations\"))))
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|     (mingetty-service-type config =>
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|                            (mingetty-configuration
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|                             (inherit config)
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|                             (motd (plain-file \"motd\" \"Hi there!\"))))
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|     (delete udev-service-type))
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| 
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| It changes the configuration of the GUIX-SERVICE-TYPE instance, and that of
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| all the MINGETTY-SERVICE-TYPE instances, and it deletes instances of the
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| UDEV-SERVICE-TYPE.
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| 
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| This is a shorthand for (filter-map (lambda (svc) ...) %base-services)."
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|     ((_ services clauses ...)
 | ||
|      (filter-map (lambda (service)
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|                    (%modify-service service clauses ...))
 | ||
|                  services))))
 | ||
| 
 | ||
| 
 | ||
| ;;;
 | ||
| ;;; Core services.
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| ;;;
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| 
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| (define (system-derivation entries mextensions)
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|   "Return as a monadic value the derivation of the 'system' directory
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| containing the given entries."
 | ||
|   (mlet %store-monad ((extensions (mapm/accumulate-builds identity
 | ||
|                                                           mextensions)))
 | ||
|     (lower-object
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|      (file-union "system"
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|                  (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
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|   ;; 'operating-system-derivation'.
 | ||
|   (service-type (name 'system)
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|                 (extensions '())
 | ||
|                 (compose identity)
 | ||
|                 (extend system-derivation)
 | ||
|                 (description
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|                  "Build the operating system top-level directory, which in
 | ||
| turn refers to everything the operating system needs: its kernel, initrd,
 | ||
| system profile, boot script, and so on.")))
 | ||
| 
 | ||
| (define (compute-boot-script _ gexps)
 | ||
|   ;; Reverse GEXPS so that extensions appear in the boot script in the right
 | ||
|   ;; order.  That is, user extensions would come first, and extensions added
 | ||
|   ;; by 'essential-services' (e.g., running shepherd) are guaranteed to come
 | ||
|   ;; last.
 | ||
|   (gexp->file "boot"
 | ||
|               ;; Clean up and activate the system, then spawn shepherd.
 | ||
|               #~(begin #$@(reverse 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.  It
 | ||
|   ;; aggregates them in a single script, as a monadic value, which becomes its
 | ||
|   ;; value.
 | ||
|   (service-type (name 'boot)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension system-service-type
 | ||
|                                           boot-script-entry)))
 | ||
|                 (compose identity)
 | ||
|                 (extend compute-boot-script)
 | ||
|                 (description
 | ||
|                  "Produce the operating system's boot script, which is spawned
 | ||
| by the initrd once the root file system is mounted.")))
 | ||
| 
 | ||
| (define %boot-service
 | ||
|   ;; The service that produces the boot script.
 | ||
|   (service boot-service-type #t))
 | ||
| 
 | ||
| 
 | ||
| ;;;
 | ||
| ;;; Provenance tracking.
 | ||
| ;;;
 | ||
| 
 | ||
| (define (object->pretty-string obj)
 | ||
|   "Like 'object->string', but using 'pretty-print'."
 | ||
|   (call-with-output-string
 | ||
|     (lambda (port)
 | ||
|       (pretty-print obj port))))
 | ||
| 
 | ||
| (define (channel->code channel)
 | ||
|   "Return code to build CHANNEL, ready to be dropped in a 'channels.scm'
 | ||
| file."
 | ||
|   ;; Since the 'introduction' field is backward-incompatible, and since it's
 | ||
|   ;; optional when using the "official" 'guix channel, include it if and only
 | ||
|   ;; if we're referring to a different channel.
 | ||
|   (let ((intro (and (not (equal? (list channel) %default-channels))
 | ||
|                     (channel-introduction channel))))
 | ||
|     `(channel (name ',(channel-name channel))
 | ||
|               (url ,(channel-url channel))
 | ||
|               (branch ,(channel-branch channel))
 | ||
|               (commit ,(channel-commit channel))
 | ||
|               ,@(if intro
 | ||
|                     `((introduction
 | ||
|                        (make-channel-introduction
 | ||
|                         ,(channel-introduction-first-signed-commit intro)
 | ||
|                         (openpgp-fingerprint
 | ||
|                          ,(openpgp-format-fingerprint
 | ||
|                            (channel-introduction-first-commit-signer
 | ||
|                             intro))))))
 | ||
|                     '()))))
 | ||
| 
 | ||
| (define (channel->sexp channel)
 | ||
|   "Return an sexp describing CHANNEL.  The sexp is _not_ code and is meant to
 | ||
| be parsed by tools; it's potentially more future-proof than code."
 | ||
|   ;; TODO: Add CHANNEL's introduction.  Currently we can't do that because
 | ||
|   ;; older 'guix system describe' expect exactly name/url/branch/commit
 | ||
|   ;; without any additional fields.
 | ||
|   `(channel (name ,(channel-name channel))
 | ||
|             (url ,(channel-url channel))
 | ||
|             (branch ,(channel-branch channel))
 | ||
|             (commit ,(channel-commit channel))))
 | ||
| 
 | ||
| (define (sexp->channel sexp)
 | ||
|   "Return the channel corresponding to SEXP, an sexp as found in the
 | ||
| \"provenance\" file produced by 'provenance-service-type'."
 | ||
|   (match sexp
 | ||
|     (('channel ('name name)
 | ||
|                ('url url)
 | ||
|                ('branch branch)
 | ||
|                ('commit commit)
 | ||
|                rest ...)
 | ||
|      ;; XXX: In the future REST may include a channel introduction.
 | ||
|      (channel (name name) (url url)
 | ||
|               (branch branch) (commit commit)))))
 | ||
| 
 | ||
| (define (provenance-file channels config-file)
 | ||
|   "Return a 'provenance' file describing CHANNELS, a list of channels, and
 | ||
| CONFIG-FILE, which can be either #f or a <local-file> containing the OS
 | ||
| configuration being used."
 | ||
|   (scheme-file "provenance"
 | ||
|                #~(provenance
 | ||
|                   (version 0)
 | ||
|                   (channels #+@(if channels
 | ||
|                                    (map channel->sexp channels)
 | ||
|                                    '()))
 | ||
|                   (configuration-file #+config-file))))
 | ||
| 
 | ||
| (define (provenance-entry config-file)
 | ||
|   "Return system entries describing the operating system provenance: the
 | ||
| channels in use and CONFIG-FILE, if it is true."
 | ||
|   (define channels
 | ||
|     (current-channels))
 | ||
| 
 | ||
|   (mbegin %store-monad
 | ||
|     (let ((config-file (cond ((string? config-file)
 | ||
|                               ;; CONFIG-FILE has been passed typically via
 | ||
|                               ;; 'guix system reconfigure CONFIG-FILE' so we
 | ||
|                               ;; can assume it's valid: tell 'local-file' to
 | ||
|                               ;; not emit a warning.
 | ||
|                               (local-file (assume-valid-file-name config-file)
 | ||
|                                           "configuration.scm"))
 | ||
|                              ((not config-file)
 | ||
|                               #f)
 | ||
|                              (else
 | ||
|                               config-file))))
 | ||
|       (return `(("provenance" ,(provenance-file channels config-file))
 | ||
|                 ,@(if channels
 | ||
|                       `(("channels.scm"
 | ||
|                          ,(plain-file "channels.scm"
 | ||
|                                       (object->pretty-string
 | ||
|                                        `(list
 | ||
|                                          ,@(map channel->code channels))))))
 | ||
|                       '())
 | ||
|                 ,@(if config-file
 | ||
|                       `(("configuration.scm" ,config-file))
 | ||
|                       '()))))))
 | ||
| 
 | ||
| (define provenance-service-type
 | ||
|   (service-type (name 'provenance)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension system-service-type
 | ||
|                                           provenance-entry)))
 | ||
|                 (default-value #f)                ;the OS config file
 | ||
|                 (description
 | ||
|                  "Store provenance information about the system in the system
 | ||
| itself: the channels used when building the system, and its configuration
 | ||
| file, when available.")))
 | ||
| 
 | ||
| (define (sexp->system-provenance sexp)
 | ||
|   "Parse SEXP, an s-expression read from /run/current-system/provenance or
 | ||
| similar, and return two values: the list of channels listed therein, and the
 | ||
| OS configuration file or #f."
 | ||
|   (match sexp
 | ||
|     (('provenance ('version 0)
 | ||
|                   ('channels channels ...)
 | ||
|                   ('configuration-file config-file))
 | ||
|      (values (map sexp->channel channels)
 | ||
|              config-file))
 | ||
|     (_
 | ||
|      (values '() #f))))
 | ||
| 
 | ||
| (define (system-provenance system)
 | ||
|   "Given SYSTEM, the file name of a system generation, return two values: the
 | ||
| list of channels SYSTEM is built from, and its configuration file.  If that
 | ||
| information is missing, return the empty list (for channels) and possibly
 | ||
| #false (for the configuration file)."
 | ||
|   (catch 'system-error
 | ||
|     (lambda ()
 | ||
|       (sexp->system-provenance
 | ||
|        (call-with-input-file (string-append system "/provenance")
 | ||
|          read)))
 | ||
|     (lambda _
 | ||
|       (values '() #f))))
 | ||
| 
 | ||
| ;;;
 | ||
| ;;; Cleanup.
 | ||
| ;;;
 | ||
| 
 | ||
| (define (cleanup-gexp _)
 | ||
|   "Return a gexp to clean up /tmp and similar places upon boot."
 | ||
|   (with-imported-modules '((guix build utils))
 | ||
|     #~(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
 | ||
|            ;; Remove stale Shadow lock files as they would lead to
 | ||
|            ;; failures of 'useradd' & co.
 | ||
|            (delete-file "/etc/group.lock")
 | ||
|            (delete-file "/etc/passwd.lock")
 | ||
|            (delete-file "/etc/.pwd.lock")         ;from 'lckpwdf'
 | ||
| 
 | ||
|            ;; Force file names to be decoded as UTF-8.  See
 | ||
|            ;; <https://bugs.gnu.org/26353>.
 | ||
|            (setenv "GUIX_LOCPATH"
 | ||
|                    #+(file-append glibc-utf8-locales "/lib/locale"))
 | ||
|            (setlocale LC_CTYPE "en_US.utf8")
 | ||
|            (delete-file-recursively "/tmp")
 | ||
|            (delete-file-recursively "/var/run")
 | ||
| 
 | ||
|            (mkdir "/tmp")
 | ||
|            (chmod "/tmp" #o1777)
 | ||
|            (mkdir "/var/run")
 | ||
|            (chmod "/var/run" #o755)
 | ||
|            (delete-file-recursively "/run/udev/watch.old"))))))
 | ||
| 
 | ||
| (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)))
 | ||
|                 (description
 | ||
|                  "Delete files from @file{/tmp}, @file{/var/run}, and other
 | ||
| temporary locations at boot time.")))
 | ||
| 
 | ||
| (define* (activation-service->script service)
 | ||
|   "Return as a monadic value the activation script for SERVICE, a service of
 | ||
| ACTIVATION-SCRIPT-TYPE."
 | ||
|   (activation-script (service-value service)))
 | ||
| 
 | ||
| (define (activation-script gexps)
 | ||
|   "Return the system's activation script, which evaluates GEXPS."
 | ||
|   (define actions
 | ||
|     (map (cut program-file "activate-service.scm" <>) gexps))
 | ||
| 
 | ||
|   (program-file "activate.scm"
 | ||
|                 (with-imported-modules (source-module-closure
 | ||
|                                         '((gnu build activation)
 | ||
|                                           (guix build utils)))
 | ||
|                   #~(begin
 | ||
|                       (use-modules (gnu build activation)
 | ||
|                                    (guix build utils))
 | ||
| 
 | ||
|                       ;; Make sure the user accounting database exists.  If it
 | ||
|                       ;; does not exist, 'setutxent' does not create it and
 | ||
|                       ;; thus there is no accounting at all.
 | ||
|                       (close-port (open-file "/var/run/utmpx" "a0"))
 | ||
| 
 | ||
|                       ;; Same for 'wtmp', which is populated by mingetty et
 | ||
|                       ;; al.
 | ||
|                       (mkdir-p "/var/log")
 | ||
|                       (close-port (open-file "/var/log/wtmp" "a0"))
 | ||
| 
 | ||
|                       ;; 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."
 | ||
|   #~(primitive-load #$(activation-script gexps)))
 | ||
| 
 | ||
| (define (activation-profile-entry gexps)
 | ||
|   "Return, as a monadic value, an entry for the activation script in the
 | ||
| system directory."
 | ||
|   (mlet %store-monad ((activate (lower-object (activation-script gexps))))
 | ||
|     (return `(("activate" ,activate)))))
 | ||
| 
 | ||
| (define (second-argument a b) b)
 | ||
| 
 | ||
| (define activation-service-type
 | ||
|   (service-type (name 'activate)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension boot-service-type
 | ||
|                                           gexps->activation-gexp)
 | ||
|                        (service-extension system-service-type
 | ||
|                                           activation-profile-entry)))
 | ||
|                 (compose identity)
 | ||
|                 (extend second-argument)
 | ||
|                 (description
 | ||
|                  "Run @dfn{activation} code at boot time and upon
 | ||
| @command{guix system reconfigure} completion.")))
 | ||
| 
 | ||
| (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")
 | ||
|                       ;; FIXME: Remove this crutch when the patch #40422,
 | ||
|                       ;; updating to kmod 27 is merged.
 | ||
|                       (setenv "MODPROBE_OPTIONS"
 | ||
|                               "-C /etc/modprobe.d")
 | ||
|                       (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
 | ||
|   ;; The service that does things that are needed on the "bare metal", but not
 | ||
|   ;; necessary or impossible in a container.
 | ||
|   (simple-service 'linux-bare-metal
 | ||
|                   activation-service-type
 | ||
|                   %linux-kernel-activation))
 | ||
| 
 | ||
| (define %hurd-rc-script
 | ||
|   ;; The RC script to be started upon boot.
 | ||
|   (program-file "rc"
 | ||
|                 (with-imported-modules (source-module-closure
 | ||
|                                         '((guix build utils)
 | ||
|                                           (gnu build hurd-boot)
 | ||
|                                           (guix build syscalls)))
 | ||
|                   #~(begin
 | ||
|                       (use-modules (guix build utils)
 | ||
|                                    (gnu build hurd-boot)
 | ||
|                                    (guix build syscalls)
 | ||
|                                    (ice-9 match)
 | ||
|                                    (system repl repl)
 | ||
|                                    (srfi srfi-1)
 | ||
|                                    (srfi srfi-26))
 | ||
|                       (boot-hurd-system)))))
 | ||
| 
 | ||
| (define (hurd-rc-entry rc)
 | ||
|   "Return, as a monadic value, an entry for the RC script in the system
 | ||
| directory."
 | ||
|   (mlet %store-monad ((rc (lower-object rc)))
 | ||
|     (return `(("rc" ,rc)))))
 | ||
| 
 | ||
| (define hurd-startup-service-type
 | ||
|   ;; The service that creates the initial SYSTEM/rc startup file.
 | ||
|   (service-type (name 'startup)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension system-service-type hurd-rc-entry)))
 | ||
|                 (default-value %hurd-rc-script)
 | ||
|                 (description "This service creates an @file{rc} script in the
 | ||
| system; that script is responsible for booting the Hurd.")))
 | ||
| 
 | ||
| (define %hurd-startup-service
 | ||
|   ;; The service that produces the RC script.
 | ||
|   (service hurd-startup-service-type %hurd-rc-script))
 | ||
| 
 | ||
| (define special-files-service-type
 | ||
|   ;; Service to install "special files" such as /bin/sh and /usr/bin/env.
 | ||
|   (service-type
 | ||
|    (name 'special-files)
 | ||
|    (extensions
 | ||
|     (list (service-extension activation-service-type
 | ||
|                              (lambda (files)
 | ||
|                                #~(activate-special-files '#$files)))))
 | ||
|    (compose concatenate)
 | ||
|    (extend append)
 | ||
|    (description
 | ||
|     "Add special files to the root file system---e.g.,
 | ||
| @file{/usr/bin/env}.")))
 | ||
| 
 | ||
| (define (extra-special-file file target)
 | ||
|   "Use TARGET as the \"special file\" FILE.  For example, TARGET might be
 | ||
|   (file-append coreutils \"/bin/env\")
 | ||
| and FILE could be \"/usr/bin/env\"."
 | ||
|   (simple-service (string->symbol (string-append "special-file-" file))
 | ||
|                   special-files-service-type
 | ||
|                   `((,file ,target))))
 | ||
| 
 | ||
| (define (etc-directory service)
 | ||
|   "Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE."
 | ||
|   (files->etc-directory (service-value service)))
 | ||
| 
 | ||
| (define (files->etc-directory files)
 | ||
|   (define (assert-no-duplicates files)
 | ||
|     (let loop ((files files)
 | ||
|                (seen (set)))
 | ||
|       (match files
 | ||
|         (() #t)
 | ||
|         (((file _) rest ...)
 | ||
|          (when (set-contains? seen file)
 | ||
|            (raise (formatted-message (G_ "duplicate '~a' entry for /etc")
 | ||
|                                      file)))
 | ||
|          (loop rest (set-insert file seen))))))
 | ||
| 
 | ||
|   ;; Detect duplicates early instead of letting them through, eventually
 | ||
|   ;; leading to a build failure of "etc.drv".
 | ||
|   (assert-no-duplicates 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)
 | ||
|                 (description "Populate the @file{/etc} directory.")))
 | ||
| 
 | ||
| (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->activation-gexp programs)
 | ||
|   "Return an activation gexp for setuid-program from PROGRAMS."
 | ||
|   (let ((programs (map (lambda (program)
 | ||
|                          ;; FIXME This is really ugly, I didn't managed to use
 | ||
|                          ;; "inherit"
 | ||
|                          (let ((program-name (setuid-program-program program))
 | ||
|                                (setuid?      (setuid-program-setuid? program))
 | ||
|                                (setgid?      (setuid-program-setgid? program))
 | ||
|                                (user         (setuid-program-user program))
 | ||
|                                (group        (setuid-program-group program)) )
 | ||
|                            #~(setuid-program
 | ||
|                               (setuid? #$setuid?)
 | ||
|                               (setgid? #$setgid?)
 | ||
|                               (user    #$user)
 | ||
|                               (group   #$group)
 | ||
|                               (program #$program-name))))
 | ||
|                        programs)))
 | ||
|     (with-imported-modules (source-module-closure
 | ||
|                             '((gnu system setuid)))
 | ||
|       #~(begin
 | ||
|           (use-modules (gnu system setuid))
 | ||
| 
 | ||
|           (activate-setuid-programs (list #$@programs))))))
 | ||
| 
 | ||
| (define setuid-program-service-type
 | ||
|   (service-type (name 'setuid-program)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension activation-service-type
 | ||
|                                           setuid-program->activation-gexp)))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend (lambda (config extensions)
 | ||
|                           (append config extensions)))
 | ||
|                 (description
 | ||
|                  "Populate @file{/run/setuid-programs} with the specified
 | ||
| executables, making them setuid and/or setgid.")))
 | ||
| 
 | ||
| (define (packages->profile-entry packages)
 | ||
|   "Return a system entry for the profile containing PACKAGES."
 | ||
|   ;; XXX: 'mlet' is needed here for one reason: to get the proper
 | ||
|   ;; '%current-target' and '%current-target-system' bindings when
 | ||
|   ;; 'packages->manifest' is called, and thus when the 'package-inputs'
 | ||
|   ;; etc. procedures are called on PACKAGES.  That way, conditionals in those
 | ||
|   ;; inputs see the "correct" value of these two parameters.  See
 | ||
|   ;; <https://issues.guix.gnu.org/44952>.
 | ||
|   (mlet %store-monad ((_ (current-target-system)))
 | ||
|     (return `(("profile" ,(profile
 | ||
|                            (content (packages->manifest
 | ||
|                                      (delete-duplicates packages eq?)))))))))
 | ||
| 
 | ||
| (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)
 | ||
|                 (description
 | ||
|                  "This is the @dfn{system profile}, available as
 | ||
| @file{/run/current-system/profile}.  It contains packages that the sysadmin
 | ||
| wants to be globally available to all the system users.")))
 | ||
| 
 | ||
| (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 #$directory "/lib/firmware"))))
 | ||
| 
 | ||
| (define firmware-service-type
 | ||
|   ;; The service that collects firmware.
 | ||
|   (service-type (name 'firmware)
 | ||
|                 (extensions
 | ||
|                  (list (service-extension activation-service-type
 | ||
|                                           firmware->activation-gexp)))
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)
 | ||
|                 (description
 | ||
|                  "Make ``firmware'' files loadable by the operating system
 | ||
| kernel.  Firmware may then be uploaded to some of the machine's devices, such
 | ||
| as Wifi cards.")))
 | ||
| 
 | ||
| (define (gc-roots->system-entry roots)
 | ||
|   "Return an entry in the system's output containing symlinks to ROOTS."
 | ||
|   (mlet %store-monad ((entry (gexp->derivation
 | ||
|                               "gc-roots"
 | ||
|                               #~(let ((roots '#$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)
 | ||
|                 (description
 | ||
|                  "Register garbage-collector roots---i.e., store items that
 | ||
| will not be reclaimed by the garbage collector.")
 | ||
|                 (default-value '())))
 | ||
| 
 | ||
| ;; Configuration for the Linux kernel builder.
 | ||
| (define-record-type* <linux-builder-configuration>
 | ||
|   linux-builder-configuration
 | ||
|   make-linux-builder-configuration
 | ||
|   linux-builder-configuration?
 | ||
|   this-linux-builder-configuration
 | ||
| 
 | ||
|   (kernel   linux-builder-configuration-kernel)                   ; package
 | ||
|   (modules  linux-builder-configuration-modules  (default '())))  ; list of packages
 | ||
| 
 | ||
| (define (package-for-kernel target-kernel module-package)
 | ||
|   "Return a package like MODULE-PACKAGE, adapted for TARGET-KERNEL, if
 | ||
| possible (that is if there's a LINUX keyword argument in the build system)."
 | ||
|   (package
 | ||
|     (inherit module-package)
 | ||
|     (arguments
 | ||
|      (substitute-keyword-arguments (package-arguments module-package)
 | ||
|        ((#:linux kernel #f)
 | ||
|         target-kernel)))))
 | ||
| 
 | ||
| (define (linux-builder-configuration->system-entry config)
 | ||
|   "Return the kernel entry of the 'system' directory."
 | ||
|   (let* ((kernel  (linux-builder-configuration-kernel config))
 | ||
|          (modules (linux-builder-configuration-modules config))
 | ||
|          (kernel  (profile
 | ||
|                     (content (packages->manifest
 | ||
|                               (cons kernel
 | ||
|                                     (map (lambda (module)
 | ||
|                                            (cond
 | ||
|                                              ((package? module)
 | ||
|                                               (package-for-kernel kernel module))
 | ||
|                                              ;; support (,package "kernel-module-output")
 | ||
|                                              ((and (list? module) (package? (car module)))
 | ||
|                                               (cons (package-for-kernel kernel
 | ||
|                                                                         (car module))
 | ||
|                                                     (cdr module)))
 | ||
|                                              (else
 | ||
|                                               module)))
 | ||
|                                          modules))))
 | ||
|                     (hooks (list linux-module-database)))))
 | ||
|     (with-monad %store-monad
 | ||
|       (return `(("kernel" ,kernel))))))
 | ||
| 
 | ||
| (define linux-builder-service-type
 | ||
|   (service-type (name 'linux-builder)
 | ||
|                 (extensions
 | ||
|                   (list (service-extension system-service-type
 | ||
|                                            linux-builder-configuration->system-entry)))
 | ||
|                 (default-value '())
 | ||
|                 (compose identity)
 | ||
|                 (extend (lambda (config modifiers)
 | ||
|                           (if (null? modifiers)
 | ||
|                               config
 | ||
|                               ((apply compose modifiers) config))))
 | ||
|                 (description "Builds the linux-libre kernel profile, containing
 | ||
| the kernel itself and any linux-loadable kernel modules.  This can be extended
 | ||
| with a function that accepts the current configuration and returns a new
 | ||
| configuration.")))
 | ||
| 
 | ||
| (define (linux-loadable-module-builder-modifier modules)
 | ||
|   "Extends linux-builder-service-type by appending the given MODULES to the
 | ||
| configuration of linux-builder-service-type."
 | ||
|   (lambda (config)
 | ||
|     (linux-builder-configuration
 | ||
|       (inherit config)
 | ||
|       (modules (append (linux-builder-configuration-modules config)
 | ||
|                        modules)))))
 | ||
| 
 | ||
| (define linux-loadable-module-service-type
 | ||
|   (service-type (name 'linux-loadable-modules)
 | ||
|                 (extensions
 | ||
|                   (list (service-extension linux-builder-service-type
 | ||
|                                            linux-loadable-module-builder-modifier)))
 | ||
|                 (default-value '())
 | ||
|                 (compose concatenate)
 | ||
|                 (extend append)
 | ||
|                 (description "Adds packages and package outputs as modules
 | ||
| included in the booted linux-libre profile.  Other services can extend this
 | ||
| service type to add particular modules to the set of linux-loadable modules.")))
 | ||
| 
 | ||
| 
 | ||
| 
 | ||
| ;;;
 | ||
| ;;; Service folding.
 | ||
| ;;;
 | ||
| 
 | ||
| (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 (missing-target-error service target-type)
 | ||
|   (raise
 | ||
|    (condition (&missing-target-service-error
 | ||
|                (service service)
 | ||
|                (target-type target-type))
 | ||
|               (&message
 | ||
|                (message
 | ||
|                 (format #f (G_ "no target of type '~a' for service '~a'")
 | ||
|                         (service-type-name target-type)
 | ||
|                         (service-type-name
 | ||
|                          (service-kind service))))))))
 | ||
| 
 | ||
| (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))
 | ||
|           (()
 | ||
|            (missing-target-error service target-type))
 | ||
|           (x
 | ||
|            (raise
 | ||
|             (condition (&ambiguous-target-service-error
 | ||
|                         (service service)
 | ||
|                         (target-type target-type))
 | ||
|                        (&message
 | ||
|                         (message
 | ||
|                          (format #f
 | ||
|                                  (G_ "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 (instantiate-missing-services services)
 | ||
|   "Return SERVICES, a list, augmented with any services targeted by extensions
 | ||
| and missing from SERVICES.  Only service types with a default value can be
 | ||
| instantiated; other missing services lead to a
 | ||
| '&missing-target-service-error'."
 | ||
|   (define (adjust-service-list svc result instances)
 | ||
|     (fold2 (lambda (extension result instances)
 | ||
|              (define target-type
 | ||
|                (service-extension-target extension))
 | ||
| 
 | ||
|              (match (vhash-assq target-type instances)
 | ||
|                (#f
 | ||
|                 (let ((default (service-type-default-value target-type)))
 | ||
|                   (if (eq? &no-default-value default)
 | ||
|                       (missing-target-error svc target-type)
 | ||
|                       (let ((new (service target-type)))
 | ||
|                         (values (cons new result)
 | ||
|                                 (vhash-consq target-type new instances))))))
 | ||
|                (_
 | ||
|                 (values result instances))))
 | ||
|            result
 | ||
|            instances
 | ||
|            (service-type-extensions (service-kind svc))))
 | ||
| 
 | ||
|   (let loop ((services services))
 | ||
|     (define instances
 | ||
|       (fold (lambda (service result)
 | ||
|               (vhash-consq (service-kind service) service
 | ||
|                            result))
 | ||
|             vlist-null services))
 | ||
| 
 | ||
|     (define adjusted
 | ||
|       (fold2 adjust-service-list
 | ||
|              services instances
 | ||
|              services))
 | ||
| 
 | ||
|     ;; If we instantiated services, they might in turn depend on missing
 | ||
|     ;; services.  Loop until we've reached fixed point.
 | ||
|     (if (= (length adjusted) (vlist-length instances))
 | ||
|         adjusted
 | ||
|         (loop adjusted))))
 | ||
| 
 | ||
| (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-value service))))))
 | ||
| 
 | ||
|   (match (filter (lambda (service)
 | ||
|                    (eq? (service-kind service) target-type))
 | ||
|                  services)
 | ||
|     ((sink)
 | ||
|      ;; Use the state monad to keep track of already-visited services in the
 | ||
|      ;; graph and to memoize their value once folded.
 | ||
|      (run-with-state
 | ||
|          (let loop ((sink sink))
 | ||
|            (mlet %state-monad ((visited (current-state)))
 | ||
|              (match (vhash-assq sink visited)
 | ||
|                (#f
 | ||
|                 (mlet* %state-monad
 | ||
|                     ((dependents (mapm %state-monad loop (dependents sink)))
 | ||
|                      (visited    (current-state))
 | ||
|                      (extensions -> (map (apply-extension sink) dependents))
 | ||
|                      (extend     -> (service-type-extend (service-kind sink)))
 | ||
|                      (compose    -> (service-type-compose (service-kind sink)))
 | ||
|                      (params     -> (service-value sink))
 | ||
|                      (service
 | ||
|                       ->
 | ||
|                       ;; 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)))
 | ||
|                   (mbegin %state-monad
 | ||
|                     (set-current-state (vhash-consq sink service visited))
 | ||
|                     (return service))))
 | ||
|                ((_ . service)                     ;SINK was already visited
 | ||
|                 (return service)))))
 | ||
|        vlist-null))
 | ||
|     (()
 | ||
|      (raise
 | ||
|       (make-compound-condition
 | ||
|        (condition (&missing-target-service-error
 | ||
|                    (service #f)
 | ||
|                    (target-type target-type)))
 | ||
|        (formatted-message (G_ "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
 | ||
|                            (G_ "more than one target service of type '~a'")
 | ||
|                            (service-type-name target-type)))))))))
 | ||
| 
 | ||
| ;;; services.scm ends here.
 |