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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 Ludovic Courtès <ludo@gnu.org>
;;;
;;; 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 sets)
#:use-module (guix ui)
#:use-module (gnu packages base)
#:use-module (gnu packages bash)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-9 gnu)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 vlist)
#:use-module (ice-9 match)
#:export (service-extension
service-extension?
service-type
service-type?
service-type-name
service-type-extensions
service-type-compose
service-type-extend
service
service?
service-kind
service-parameters
modify-services
service-back-edges
fold-services
service-error?
missing-target-service-error?
missing-target-service-error-service
missing-target-service-error-target-type
ambiguous-target-service-error?
ambiguous-target-service-error-service
ambiguous-target-service-error-target-type
boot-service-type
activation-service-type
activation-service->script
%linux-bare-metal-service
etc-service-type
etc-directory
setuid-program-service-type
firmware-service-type
%boot-service
%activation-service
etc-service
file-union)) ;XXX: for lack of a better place
;;; Comment:
;;;
;;; This module defines a broad notion of "service types" and "services."
;;;
;;; A service type describe how its instances extend instances of other
;;; service types. For instance, some services extend the instance of
;;; ACCOUNT-SERVICE-TYPE by providing it with accounts and groups to create;
;;; others extend DMD-ROOT-SERVICE-TYPE by passing it instances of
;;; <dmd-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 BOOT-SERVICE-TYPE, which has a single instance,
;;; %BOOT-SERVICE. %BOOT-SERVICE constitutes the root of the service DAG. It
;;; produces the boot script that the initrd loads.
;;;
;;; The 'fold-services' procedure can be passed a list of procedures, which it
;;; "folds" by propagating extensions down the graph; it returns the root
;;; service after the applying all its extensions.
;;;
;;; Code:
(define-record-type <service-extension>
(service-extension target compute)
service-extension?
(target service-extension-target) ;<service-type>
(compute service-extension-compute)) ;params -> params
(define-record-type* <service-type> service-type make-service-type
service-type?
(name service-type-name) ;symbol (for debugging)
;; Things extended by services of this type.
(extensions service-type-extensions) ;list of <service-extensions>
;; Given a list of extensions, "compose" them.
(compose service-type-compose ;list of Any -> Any
(default #f))
;; Extend the services' own parameters with the extension composition.
(extend service-type-extend ;list of Any -> parameters
(default #f)))
(define (write-service-type type port)
(format port "#<service-type ~a ~a>"
(service-type-name type)
(number->string (object-address type) 16)))
(set-record-type-printer! <service-type> write-service-type)
;; Services of a given type.
(define-record-type <service>
(service type parameters)
service?
(type service-kind)
(parameters service-parameters))
(define-syntax %modify-service
(syntax-rules (=>)
((_ service)
service)
((_ svc (kind param => exp ...) clauses ...)
(if (eq? (service-kind svc) kind)
(let ((param (service-parameters svc)))
(service (service-kind svc)
(begin exp ...)))
(%modify-service svc clauses ...)))))
(define-syntax modify-services
(syntax-rules ()
"Modify the services listed in SERVICES according to CLAUSES. 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 (compute-boot-script mexps)
(mlet %store-monad ((gexps (sequence %store-monad mexps)))
(gexp->file "boot"
#~(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.
(false-if-exception (delete-file-recursively "/tmp"))
(false-if-exception (delete-file-recursively "/var/run"))
(false-if-exception (mkdir "/tmp"))
(false-if-exception (chmod "/tmp" #o1777))
(false-if-exception (mkdir "/var/run"))
(false-if-exception (chmod "/var/run" #o755))
;; Activate the system and spawn dmd.
#$@gexps))))
(define (second-argument a b) b)
(define boot-service-type
;; The service of this type is extended by being passed gexps as monadic
;; values. It aggregates them in a single script, as a monadic value, which
;; becomes its 'parameters'. It is the only service that extends nothing.
(service-type (name 'boot)
(extensions '())
(compose compute-boot-script)
(extend second-argument)))
(define %boot-service
;; This is the ultimate service, the root of the service DAG.
(service boot-service-type #t))
(define* (file-union name files) ;FIXME: Factorize.
"Return a <computed-file> that builds a directory containing all of FILES.
Each item in FILES must be a list where the first element is the file name to
use in the new directory, and the second element is a gexp denoting the target
file."
(computed-file name
#~(begin
(mkdir #$output)
(chdir #$output)
#$@(map (match-lambda
((target source)
#~(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
#~(begin
(use-modules (guix build union))
(union-build #$output '#$things))
#:modules '((guix build union))))))
(define* (activation-service->script service)
"Return as a monadic value the activation script for SERVICE, a service of
ACTIVATION-SCRIPT-TYPE."
(activation-script (service-parameters service)))
(define (activation-script gexps)
"Return the system's activation script, which evaluates GEXPS."
(define %modules
'((gnu build activation)
(gnu build linux-boot)
(gnu build linux-modules)
(gnu build file-systems)
(guix build utils)
(guix build syscalls)
(guix elf)))
(define (service-activations)
;; Return the activation scripts for SERVICES.
(mapm %store-monad
(cut gexp->file "activate-service" <>)
gexps))
(mlet* %store-monad ((actions (service-activations))
(modules (imported-modules %modules))
(compiled (compiled-modules %modules)))
(gexp->file "activate"
#~(begin
(eval-when (expand load eval)
;; Make sure 'use-modules' below succeeds.
(set! %load-path (cons #$modules %load-path))
(set! %load-compiled-path
(cons #$compiled %load-compiled-path)))
(use-modules (gnu build activation))
;; Make sure /bin/sh is valid and current.
(activate-/bin/sh
(string-append #$(canonical-package bash) "/bin/sh"))
;; Run the services' activation snippets.
;; TODO: Use 'load-compiled'.
(for-each primitive-load '#$actions)
;; Set up /run/current-system.
(activate-current-system)))))
(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 #$script))))
(define activation-service-type
(service-type (name 'activate)
(extensions
(list (service-extension boot-service-type
gexps->activation-gexp)))
(compose append)
(extend second-argument)))
(define %activation-service
;; The activation service produces the activation script from the gexps it
;; receives.
(service activation-service-type #t))
(define %modprobe-wrapper
;; Wrapper for the 'modprobe' command that knows where modules live.
;;
;; This wrapper is typically invoked by the Linux kernel ('call_modprobe',
;; in kernel/kmod.c), a situation where the 'LINUX_MODULE_DIRECTORY'
;; environment variable is not set---hence the need for this wrapper.
(let ((modprobe "/run/current-system/profile/bin/modprobe"))
(program-file "modprobe"
#~(begin
(setenv "LINUX_MODULE_DIRECTORY"
"/run/booted-system/kernel/lib/modules")
(apply execl #$modprobe
(cons #$modprobe (cdr (command-line))))))))
(define %linux-kernel-activation
;; Activation of the Linux kernel running on the bare metal (as opposed to
;; running in a container.)
#~(begin
;; Tell the kernel to use our 'modprobe' command.
(activate-modprobe #$%modprobe-wrapper)
;; Let users debug their own processes!
(activate-ptrace-attach)))
(define linux-bare-metal-service-type
(service-type (name 'linux-bare-metal)
(extensions
(list (service-extension activation-service-type
(const %linux-kernel-activation))))))
(define %linux-bare-metal-service
;; The service that does things that are needed on the "bare metal", but not
;; necessary or impossible in a container.
(service linux-bare-metal-service-type #f))
(define (etc-directory service)
"Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE."
(files->etc-directory (service-parameters service)))
(define (files->etc-directory files)
(file-union "etc" files))
(define etc-service-type
(service-type (name 'etc)
(extensions
(list
(service-extension activation-service-type
(lambda (files)
(let ((etc
(files->etc-directory files)))
#~(activate-etc #$etc))))))
(compose concatenate)
(extend append)))
(define (etc-service files)
"Return a new service of ETC-SERVICE-TYPE that populates /etc with FILES.
FILES must be a list of name/file-like object pairs."
(service etc-service-type files))
(define setuid-program-service-type
(service-type (name 'setuid-program)
(extensions
(list (service-extension activation-service-type
(lambda (programs)
#~(activate-setuid-programs
(list #$@programs))))))
(compose concatenate)
(extend append)))
(define (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)))
;;;
;;; Service folding.
;;;
(define-condition-type &service-error &error
service-error?)
(define-condition-type &missing-target-service-error &service-error
missing-target-service-error?
(service missing-target-service-error-service)
(target-type missing-target-service-error-target-type))
(define-condition-type &ambiguous-target-service-error &service-error
ambiguous-target-service-error?
(service ambiguous-target-service-error-service)
(target-type ambiguous-target-service-error-target-type))
(define (service-back-edges services)
"Return a procedure that, when passed a <service>, returns the list of
<service> objects that depend on it."
(define (add-edges service edges)
(define (add-edge extension edges)
(let ((target-type (service-extension-target extension)))
(match (filter (lambda (service)
(eq? (service-kind service) target-type))
services)
((target)
(vhash-consq target service edges))
(()
(raise
(condition (&missing-target-service-error
(service service)
(target-type target-type))
(&message
(message
(format #f (_ "no target of type '~a' for service ~s")
(service-type-name target-type)
service))))))
(x
(raise
(condition (&ambiguous-target-service-error
(service service)
(target-type target-type))
(&message
(message
(format #f
(_ "more than one target service of type '~a'")
(service-type-name target-type))))))))))
(fold add-edge edges (service-type-extensions (service-kind service))))
(let ((edges (fold add-edges vlist-null services)))
(lambda (node)
(reverse (vhash-foldq* cons '() node edges)))))
(define* (fold-services services #:key (target-type boot-service-type))
"Fold SERVICES by propagating their extensions down to the root of type
TARGET-TYPE; return the root service adjusted accordingly."
(define dependents
(service-back-edges services))
(define (matching-extension target)
(let ((target (service-kind target)))
(match-lambda
(($ <service-extension> type)
(eq? type target)))))
(define (apply-extension target)
(lambda (service)
(match (find (matching-extension target)
(service-type-extensions (service-kind service)))
(($ <service-extension> _ compute)
(compute (service-parameters service))))))
(match (filter (lambda (service)
(eq? (service-kind service) target-type))
services)
((sink)
(let loop ((sink sink))
(let* ((dependents (map loop (dependents sink)))
(extensions (map (apply-extension sink) dependents))
(extend (service-type-extend (service-kind sink)))
(compose (service-type-compose (service-kind sink)))
(params (service-parameters sink)))
;; We distinguish COMPOSE and EXTEND because PARAMS typically has a
;; different type than the elements of EXTENSIONS.
(if extend
(service (service-kind sink)
(extend params (compose extensions)))
sink))))
(()
(raise
(condition (&missing-target-service-error
(service #f)
(target-type target-type))
(&message
(message (format #f (_ "service of type '~a' not found")
(service-type-name target-type)))))))
(x
(raise
(condition (&ambiguous-target-service-error
(service #f)
(target-type target-type))
(&message
(message
(format #f
(_ "more than one target service of type '~a'")
(service-type-name target-type)))))))))
;;; services.scm ends here.