aad8a14300
Partly fixes <https://bugs.gnu.org/28772>. Reported by Oleg Pykhalov <go.wigust@gmail.com>. * gnu/services.scm (cleanup-gexp): Remove /etc/{passwd,group}.lock and /etc/.pwd.lock.
746 lines
28 KiB
Scheme
746 lines
28 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
|
||
;;; Copyright © 2015, 2016, 2017 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 discovery)
|
||
#:use-module (guix sets)
|
||
#:use-module (guix ui)
|
||
#:use-module ((guix utils) #:select (source-properties->location))
|
||
#: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-extension-target
|
||
service-extension-compute
|
||
|
||
service-type
|
||
service-type?
|
||
service-type-name
|
||
service-type-extensions
|
||
service-type-compose
|
||
service-type-extend
|
||
service-type-default-value
|
||
service-type-description
|
||
service-type-location
|
||
|
||
%service-type-path
|
||
fold-service-types
|
||
|
||
service
|
||
service?
|
||
service-kind
|
||
service-value
|
||
service-parameters ;deprecated
|
||
|
||
simple-service
|
||
modify-services
|
||
service-back-edges
|
||
fold-services
|
||
|
||
service-error?
|
||
missing-value-service-error?
|
||
missing-value-service-error-type
|
||
missing-value-service-error-location
|
||
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
|
||
special-files-service-type
|
||
extra-special-file
|
||
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
|
||
directory-union))
|
||
|
||
;;; 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 &no-default-value
|
||
;; Value used to denote service types that have no associated default value.
|
||
'(no default value))
|
||
|
||
(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))
|
||
|
||
;; Optional default value for instances of this type.
|
||
(default-value service-type-default-value ;Any
|
||
(default &no-default-value))
|
||
|
||
;; Meta-data.
|
||
(description service-type-description ;string
|
||
(default #f))
|
||
(location service-type-location ;<location>
|
||
(default (and=> (current-source-location)
|
||
source-properties->location))
|
||
(innate)))
|
||
|
||
(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)
|
||
|
||
(define %distro-root-directory
|
||
;; Absolute file name of the module hierarchy.
|
||
(dirname (search-path %load-path "guix.scm")))
|
||
|
||
(define %service-type-path
|
||
;; Search path for service types.
|
||
(make-parameter `((,%distro-root-directory . "gnu/services")
|
||
(,%distro-root-directory . "gnu/system"))))
|
||
|
||
(define* (fold-service-types proc seed
|
||
#:optional
|
||
(modules (all-modules (%service-type-path))))
|
||
"For each service type exported by one of MODULES, call (PROC RESULT). SEED
|
||
is used as the initial value of RESULT."
|
||
(fold-module-public-variables (lambda (object result)
|
||
(if (service-type? object)
|
||
(proc object result)
|
||
result))
|
||
'()
|
||
modules))
|
||
|
||
;; Services of a given type.
|
||
(define-record-type <service>
|
||
(make-service type value)
|
||
service?
|
||
(type service-kind)
|
||
(value service-value))
|
||
|
||
(define-syntax service
|
||
(syntax-rules ()
|
||
"Return a service instance of TYPE. The service value is VALUE or, if
|
||
omitted, TYPE's default value."
|
||
((_ type value)
|
||
(make-service type value))
|
||
((_ type)
|
||
(%service-with-default-value (current-source-location)
|
||
type))))
|
||
|
||
(define (%service-with-default-value location type)
|
||
"Return a instance of service type TYPE with its default value, if any. If
|
||
TYPE does not have a default value, an error is raised."
|
||
;; TODO: Currently this is a run-time error but with a little bit macrology
|
||
;; we could turn it into an expansion-time error.
|
||
(let ((default (service-type-default-value type)))
|
||
(if (eq? default &no-default-value)
|
||
(let ((location (source-properties->location location)))
|
||
(raise
|
||
(condition
|
||
(&missing-value-service-error (type type) (location location))
|
||
(&message
|
||
(message (format #f (G_ "~a: no value specified \
|
||
for service of type '~a'")
|
||
(location->string location)
|
||
(service-type-name type)))))))
|
||
(service type default))))
|
||
|
||
(define-condition-type &service-error &error
|
||
service-error?)
|
||
|
||
(define-condition-type &missing-value-service-error &service-error
|
||
missing-value-service-error?
|
||
(type missing-value-service-error-type)
|
||
(location missing-value-service-error-location))
|
||
|
||
|
||
|
||
;;;
|
||
;;; Helpers.
|
||
;;;
|
||
|
||
(define service-parameters
|
||
;; Deprecated alias.
|
||
service-value)
|
||
|
||
(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-value 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
|
||
;; 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'
|
||
|
||
(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 '#$things)))))))
|
||
|
||
(define* (activation-service->script service)
|
||
"Return as a monadic value the activation script for SERVICE, a service of
|
||
ACTIVATION-SCRIPT-TYPE."
|
||
(activation-script (service-value service)))
|
||
|
||
(define (activation-script gexps)
|
||
"Return the system's activation script, which evaluates GEXPS."
|
||
(define (service-activations)
|
||
;; Return the activation scripts for SERVICES.
|
||
(mapm %store-monad
|
||
(cut gexp->file "activate-service" <>)
|
||
gexps))
|
||
|
||
(mlet* %store-monad ((actions (service-activations)))
|
||
(gexp->file "activate"
|
||
(with-imported-modules (source-module-closure
|
||
'((gnu build activation)
|
||
(guix build utils)))
|
||
#~(begin
|
||
(use-modules (gnu build activation)
|
||
(guix build utils))
|
||
|
||
;; Make sure the user accounting database exists. If it
|
||
;; does not exist, 'setutxent' does not create it and
|
||
;; thus there is no accounting at all.
|
||
(close-port (open-file "/var/run/utmpx" "a0"))
|
||
|
||
;; Same for 'wtmp', which is populated by mingetty et
|
||
;; al.
|
||
(mkdir-p "/var/log")
|
||
(close-port (open-file "/var/log/wtmp" "a0"))
|
||
|
||
;; Set up /run/current-system. Among other things this
|
||
;; sets up locales, which the activation snippets
|
||
;; executed below may expect.
|
||
(activate-current-system)
|
||
|
||
;; Run the services' activation snippets.
|
||
;; TODO: Use 'load-compiled'.
|
||
(for-each primitive-load '#$actions))))))
|
||
|
||
(define (gexps->activation-gexp gexps)
|
||
"Return a gexp that runs the activation script containing GEXPS."
|
||
(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
|
||
;; 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 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 '#$files)))))
|
||
(compose concatenate)
|
||
(extend append)))
|
||
|
||
(define (extra-special-file file target)
|
||
"Use TARGET as the \"special file\" FILE. For example, TARGET might be
|
||
(file-append coreutils \"/bin/env\")
|
||
and FILE could be \"/usr/bin/env\"."
|
||
(simple-service (string->symbol (string-append "special-file-" file))
|
||
special-files-service-type
|
||
`((,file ,target))))
|
||
|
||
(define (etc-directory service)
|
||
"Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE."
|
||
(files->etc-directory (service-value service)))
|
||
|
||
(define (files->etc-directory files)
|
||
(file-union "etc" files))
|
||
|
||
(define (etc-entry files)
|
||
"Return an entry for the /etc directory consisting of FILES in the system
|
||
directory."
|
||
(with-monad %store-monad
|
||
(return `(("etc" ,(files->etc-directory files))))))
|
||
|
||
(define etc-service-type
|
||
(service-type (name 'etc)
|
||
(extensions
|
||
(list
|
||
(service-extension activation-service-type
|
||
(lambda (files)
|
||
(let ((etc
|
||
(files->etc-directory files)))
|
||
#~(activate-etc #$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 &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 (G_ "no target of type '~a' for service '~a'")
|
||
(service-type-name target-type)
|
||
(service-type-name
|
||
(service-kind service))))))))
|
||
(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* (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)
|
||
(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-value 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 (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.
|