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* gnu/services.scm: Export service-extension-target and service-extension-compute. This allows for greater extensiblity of services by enabling service extensions to be wrapped. For example, the parameters passed to the compute function can be modified, or the return value of the compute function can be modified. Signed-off-by: Ludovic Courtès <ludo@gnu.org>
619 lines
24 KiB
Scheme
619 lines
24 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2015, 2016 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu services)
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#: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 sets)
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#:use-module (guix ui)
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#:use-module (guix modules)
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#:use-module (gnu packages base)
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#:use-module (gnu packages bash)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-9)
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#: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)
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#:use-module (ice-9 vlist)
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#:use-module (ice-9 match)
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#:export (service-extension
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service-extension?
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service-extension-target
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service-extension-compute
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service-type
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service-type?
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service-type-name
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service-type-extensions
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service-type-compose
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service-type-extend
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service
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service?
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service-kind
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service-parameters
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simple-service
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modify-services
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service-back-edges
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fold-services
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service-error?
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missing-target-service-error?
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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
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system-service-type
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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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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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%boot-service
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%activation-service
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etc-service
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file-union)) ;XXX: for lack of a better place
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;;; Comment:
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;;;
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;;; This module defines a broad notion of "service types" and "services."
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;;;
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;;; A service type describe how its instances extend instances of other
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;;; 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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(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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(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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;; Things extended by services of this type.
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(extensions service-type-extensions) ;list of <service-extensions>
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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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;; 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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(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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(set-record-type-printer! <service-type> write-service-type)
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;; Services of a given type.
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(define-record-type <service>
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(service type parameters)
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service?
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(type service-kind)
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(parameters service-parameters))
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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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(service type value)))
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(define-syntax %modify-service
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(syntax-rules (=>)
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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-parameters 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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(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. 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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It changes the configuration of the GUIX-SERVICE-TYPE instance, and that of
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all the MINGETTY-SERVICE-TYPE instances.
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This is a shorthand for (map (lambda (svc) ...) %base-services)."
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((_ services clauses ...)
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(map (lambda (service)
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(%modify-service service clauses ...))
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services))))
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;;;
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;;; Core services.
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;;;
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(define (system-derivation mentries mextensions)
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"Return as a monadic value the derivation of the 'system' directory
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containing the given entries."
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(mlet %store-monad ((entries mentries)
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(extensions (sequence %store-monad mextensions)))
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(lower-object
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(file-union "system"
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(append entries (concatenate extensions))))))
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(define system-service-type
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;; This is the ultimate service type, the root of the service DAG. The
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;; service of this type is extended by monadic name/item pairs. These items
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;; end up in the "system directory" as returned by
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;; 'operating-system-derivation'.
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(service-type (name 'system)
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(extensions '())
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(compose identity)
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(extend system-derivation)))
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(define (compute-boot-script _ mexps)
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(mlet %store-monad ((gexps (sequence %store-monad mexps)))
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(gexp->file "boot"
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;; Clean up and activate the system, then spawn shepherd.
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#~(begin #$@gexps))))
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(define (boot-script-entry mboot)
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"Return, as a monadic value, an entry for the boot script in the system
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directory."
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(mlet %store-monad ((boot mboot))
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(return `(("boot" ,boot)))))
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(define boot-service-type
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;; The service of this type is extended by being passed gexps as monadic
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;; values. It aggregates them in a single script, as a monadic value, which
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;; becomes its 'parameters'. It is the only service that extends nothing.
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(service-type (name 'boot)
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(extensions
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(list (service-extension system-service-type
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boot-script-entry)))
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(compose append)
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(extend compute-boot-script)))
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(define %boot-service
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;; The service that produces the boot script.
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(service boot-service-type #t))
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(define (cleanup-gexp _)
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"Return as a monadic value a gexp to clean up /tmp and similar places upon
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boot."
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(with-monad %store-monad
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(with-imported-modules '((guix build utils))
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(return #~(begin
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(use-modules (guix build utils))
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;; Clean out /tmp and /var/run.
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;;
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;; XXX This needs to happen before service activations, so it
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;; has to be here, but this also implicitly assumes that /tmp
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;; and /var/run are on the root partition.
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(letrec-syntax ((fail-safe (syntax-rules ()
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((_ exp rest ...)
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(begin
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(catch 'system-error
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(lambda () exp)
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(const #f))
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(fail-safe rest ...)))
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((_)
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#t))))
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;; Ignore I/O errors so the system can boot.
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(fail-safe
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(delete-file-recursively "/tmp")
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(delete-file-recursively "/var/run")
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(mkdir "/tmp")
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(chmod "/tmp" #o1777)
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(mkdir "/var/run")
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(chmod "/var/run" #o755))))))))
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(define cleanup-service-type
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;; Service that cleans things up in /tmp and similar.
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(service-type (name 'cleanup)
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(extensions
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(list (service-extension boot-service-type
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cleanup-gexp)))))
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(define* (file-union name files) ;FIXME: Factorize.
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"Return a <computed-file> that builds a directory containing all of FILES.
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Each item in FILES must be a list where the first element is the file name to
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use in the new directory, and the second element is a gexp denoting the target
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file."
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(computed-file name
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#~(begin
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(mkdir #$output)
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(chdir #$output)
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#$@(map (match-lambda
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((target source)
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#~(begin
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;; Stat the source to abort early if it
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;; does not exist.
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(stat #$source)
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(symlink #$source #$target))))
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files))))
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(define (directory-union name things)
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"Return a directory that is the union of THINGS."
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(match things
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((one)
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;; Only one thing; return it.
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one)
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(_
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(computed-file name
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(with-imported-modules '((guix build union))
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#~(begin
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(use-modules (guix build union))
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(union-build #$output '#$things)))))))
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(define* (activation-service->script service)
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"Return as a monadic value the activation script for SERVICE, a service of
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ACTIVATION-SCRIPT-TYPE."
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(activation-script (service-parameters service)))
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(define (activation-script gexps)
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"Return the system's activation script, which evaluates GEXPS."
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(define (service-activations)
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;; Return the activation scripts for SERVICES.
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(mapm %store-monad
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(cut gexp->file "activate-service" <>)
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gexps))
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(mlet* %store-monad ((actions (service-activations)))
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(gexp->file "activate"
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(with-imported-modules (source-module-closure
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'((gnu build activation)))
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#~(begin
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(use-modules (gnu build activation))
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;; Make sure /bin/sh is valid and current.
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(activate-/bin/sh
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(string-append #$(canonical-package bash) "/bin/sh"))
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;; Set up /run/current-system. Among other things this
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;; sets up locales, which the activation snippets
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;; executed below may expect.
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(activate-current-system)
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;; Run the services' activation snippets.
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;; TODO: Use 'load-compiled'.
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(for-each primitive-load '#$actions))))))
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(define (gexps->activation-gexp gexps)
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"Return a gexp that runs the activation script containing GEXPS."
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(mlet %store-monad ((script (activation-script gexps)))
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(return #~(primitive-load #$script))))
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(define (second-argument a b) b)
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(define activation-service-type
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(service-type (name 'activate)
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(extensions
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(list (service-extension boot-service-type
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gexps->activation-gexp)))
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(compose append)
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(extend second-argument)))
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(define %activation-service
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;; The activation service produces the activation script from the gexps it
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;; receives.
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(service activation-service-type #t))
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(define %modprobe-wrapper
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;; Wrapper for the 'modprobe' command that knows where modules live.
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;;
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;; This wrapper is typically invoked by the Linux kernel ('call_modprobe',
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;; in kernel/kmod.c), a situation where the 'LINUX_MODULE_DIRECTORY'
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;; environment variable is not set---hence the need for this wrapper.
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(let ((modprobe "/run/current-system/profile/bin/modprobe"))
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(program-file "modprobe"
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#~(begin
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(setenv "LINUX_MODULE_DIRECTORY"
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"/run/booted-system/kernel/lib/modules")
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(apply execl #$modprobe
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(cons #$modprobe (cdr (command-line))))))))
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(define %linux-kernel-activation
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;; Activation of the Linux kernel running on the bare metal (as opposed to
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;; running in a container.)
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#~(begin
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;; Tell the kernel to use our 'modprobe' command.
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(activate-modprobe #$%modprobe-wrapper)
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;; Let users debug their own processes!
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(activate-ptrace-attach)))
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(define linux-bare-metal-service-type
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(service-type (name 'linux-bare-metal)
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(extensions
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(list (service-extension activation-service-type
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(const %linux-kernel-activation))))))
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(define %linux-bare-metal-service
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;; The service that does things that are needed on the "bare metal", but not
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;; necessary or impossible in a container.
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(service linux-bare-metal-service-type #f))
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(define (etc-directory service)
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"Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE."
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(files->etc-directory (service-parameters service)))
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(define (files->etc-directory files)
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(file-union "etc" files))
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(define (etc-entry files)
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"Return an entry for the /etc directory consisting of FILES in the system
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directory."
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(with-monad %store-monad
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(return `(("etc" ,(files->etc-directory files))))))
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(define etc-service-type
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(service-type (name 'etc)
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(extensions
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(list
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(service-extension activation-service-type
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(lambda (files)
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(let ((etc
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(files->etc-directory files)))
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#~(activate-etc #$etc))))
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(service-extension system-service-type etc-entry)))
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(compose concatenate)
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(extend append)))
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(define (etc-service files)
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"Return a new service of ETC-SERVICE-TYPE that populates /etc with FILES.
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FILES must be a list of name/file-like object pairs."
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(service etc-service-type files))
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(define setuid-program-service-type
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(service-type (name 'setuid-program)
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(extensions
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(list (service-extension activation-service-type
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(lambda (programs)
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#~(activate-setuid-programs
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(list #$@programs))))))
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(compose concatenate)
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(extend append)))
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(define (packages->profile-entry packages)
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"Return a system entry for the profile containing PACKAGES."
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(mlet %store-monad ((profile (profile-derivation
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(packages->manifest
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(delete-duplicates packages eq?)))))
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(return `(("profile" ,profile)))))
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(define profile-service-type
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;; The service that populates the system's profile---i.e.,
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;; /run/current-system/profile. It is extended by package lists.
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(service-type (name 'profile)
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(extensions
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(list (service-extension system-service-type
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packages->profile-entry)))
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(compose concatenate)
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(extend append)))
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(define (firmware->activation-gexp firmware)
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"Return a gexp to make the packages listed in FIRMWARE loadable by the
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kernel."
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(let ((directory (directory-union "firmware" firmware)))
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;; Tell the kernel where firmware is.
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#~(activate-firmware (string-append #$directory "/lib/firmware"))))
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(define firmware-service-type
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;; The service that collects firmware.
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(service-type (name 'firmware)
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(extensions
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(list (service-extension activation-service-type
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firmware->activation-gexp)))
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(compose concatenate)
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(extend append)))
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(define (gc-roots->system-entry roots)
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"Return an entry in the system's output containing symlinks to ROOTS."
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(mlet %store-monad ((entry (gexp->derivation
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"gc-roots"
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#~(let ((roots '#$roots))
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(mkdir #$output)
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(chdir #$output)
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(for-each symlink
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roots
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(map number->string
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(iota (length roots))))))))
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(return (if (null? roots)
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'()
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`(("gc-roots" ,entry))))))
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(define gc-root-service-type
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;; A service to associate extra garbage-collector roots to the system. This
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;; is a simple hack that guarantees that the system retains references to
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;; the given list of roots. Roots must be "lowerable" objects like
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;; packages, or derivations.
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(service-type (name 'gc-roots)
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(extensions
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(list (service-extension system-service-type
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gc-roots->system-entry)))
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(compose concatenate)
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(extend append)))
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;;;
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;;; Service folding.
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||
;;;
|
||
|
||
(define-condition-type &service-error &error
|
||
service-error?)
|
||
|
||
(define-condition-type &missing-target-service-error &service-error
|
||
missing-target-service-error?
|
||
(service missing-target-service-error-service)
|
||
(target-type missing-target-service-error-target-type))
|
||
|
||
(define-condition-type &ambiguous-target-service-error &service-error
|
||
ambiguous-target-service-error?
|
||
(service ambiguous-target-service-error-service)
|
||
(target-type ambiguous-target-service-error-target-type))
|
||
|
||
(define (service-back-edges services)
|
||
"Return a procedure that, when passed a <service>, returns the list of
|
||
<service> objects that depend on it."
|
||
(define (add-edges service edges)
|
||
(define (add-edge extension edges)
|
||
(let ((target-type (service-extension-target extension)))
|
||
(match (filter (lambda (service)
|
||
(eq? (service-kind service) target-type))
|
||
services)
|
||
((target)
|
||
(vhash-consq target service edges))
|
||
(()
|
||
(raise
|
||
(condition (&missing-target-service-error
|
||
(service service)
|
||
(target-type target-type))
|
||
(&message
|
||
(message
|
||
(format #f (_ "no target of type '~a' for service ~s")
|
||
(service-type-name target-type)
|
||
service))))))
|
||
(x
|
||
(raise
|
||
(condition (&ambiguous-target-service-error
|
||
(service service)
|
||
(target-type target-type))
|
||
(&message
|
||
(message
|
||
(format #f
|
||
(_ "more than one target service of type '~a'")
|
||
(service-type-name target-type))))))))))
|
||
|
||
(fold add-edge edges (service-type-extensions (service-kind service))))
|
||
|
||
(let ((edges (fold add-edges vlist-null services)))
|
||
(lambda (node)
|
||
(reverse (vhash-foldq* cons '() node edges)))))
|
||
|
||
(define* (fold-services services
|
||
#:key (target-type system-service-type))
|
||
"Fold SERVICES by propagating their extensions down to the root of type
|
||
TARGET-TYPE; return the root service adjusted accordingly."
|
||
(define dependents
|
||
(service-back-edges services))
|
||
|
||
(define (matching-extension target)
|
||
(let ((target (service-kind target)))
|
||
(match-lambda
|
||
(($ <service-extension> type)
|
||
(eq? type target)))))
|
||
|
||
(define (apply-extension target)
|
||
(lambda (service)
|
||
(match (find (matching-extension target)
|
||
(service-type-extensions (service-kind service)))
|
||
(($ <service-extension> _ compute)
|
||
(compute (service-parameters service))))))
|
||
|
||
(match (filter (lambda (service)
|
||
(eq? (service-kind service) target-type))
|
||
services)
|
||
((sink)
|
||
(let loop ((sink sink))
|
||
(let* ((dependents (map loop (dependents sink)))
|
||
(extensions (map (apply-extension sink) dependents))
|
||
(extend (service-type-extend (service-kind sink)))
|
||
(compose (service-type-compose (service-kind sink)))
|
||
(params (service-parameters sink)))
|
||
;; We distinguish COMPOSE and EXTEND because PARAMS typically has a
|
||
;; different type than the elements of EXTENSIONS.
|
||
(if extend
|
||
(service (service-kind sink)
|
||
(extend params (compose extensions)))
|
||
sink))))
|
||
(()
|
||
(raise
|
||
(condition (&missing-target-service-error
|
||
(service #f)
|
||
(target-type target-type))
|
||
(&message
|
||
(message (format #f (_ "service of type '~a' not found")
|
||
(service-type-name target-type)))))))
|
||
(x
|
||
(raise
|
||
(condition (&ambiguous-target-service-error
|
||
(service #f)
|
||
(target-type target-type))
|
||
(&message
|
||
(message
|
||
(format #f
|
||
(_ "more than one target service of type '~a'")
|
||
(service-type-name target-type)))))))))
|
||
|
||
;;; services.scm ends here.
|