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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016 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 shepherd)
#:use-module (guix ui)
#:use-module (guix sets)
#:use-module (guix gexp)
#:use-module (guix store)
#:use-module (guix monads)
#:use-module (guix records)
#:use-module (guix derivations) ;imported-modules, etc.
#:use-module (gnu services)
#:use-module (gnu packages admin)
#:use-module (ice-9 match)
#:use-module (ice-9 vlist)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:export (shepherd-root-service-type
%shepherd-root-service
shepherd-service-type
shepherd-service
shepherd-service?
shepherd-service-documentation
shepherd-service-provision
shepherd-service-canonical-name
shepherd-service-requirement
shepherd-service-respawn?
shepherd-service-start
shepherd-service-stop
shepherd-service-auto-start?
shepherd-service-modules
%default-modules
shepherd-service-file
shepherd-service-back-edges))
;;; Commentary:
;;;
;;; Instantiating system services as a shepherd configuration file.
;;;
;;; Code:
(define (shepherd-boot-gexp services)
(mlet %store-monad ((shepherd-conf (shepherd-configuration-file services)))
(return #~(begin
;; Keep track of the booted system.
(false-if-exception (delete-file "/run/booted-system"))
(symlink (readlink "/run/current-system")
"/run/booted-system")
;; Close any remaining open file descriptors to be on the safe
;; side. This must be the very last thing we do, because
;; Guile has internal FDs such as 'sleep_pipe' that need to be
;; alive.
(let loop ((fd 3))
(when (< fd 1024)
(false-if-exception (close-fdes fd))
(loop (+ 1 fd))))
;; Start shepherd.
(execl (string-append #$shepherd "/bin/shepherd")
"shepherd" "--config" #$shepherd-conf)))))
(define shepherd-root-service-type
(service-type
(name 'shepherd-root)
;; Extending the root shepherd service (aka. PID 1) happens by
;; concatenating the list of services provided by the extensions.
(compose concatenate)
(extend append)
(extensions (list (service-extension boot-service-type
shepherd-boot-gexp)
(service-extension profile-service-type
(const (list shepherd)))))))
(define %shepherd-root-service
;; The root shepherd service, aka. PID 1. Its parameter is a list of
;; <shepherd-service> objects.
(service shepherd-root-service-type '()))
(define-syntax-rule (shepherd-service-type service-name proc)
"Return a <service-type> denoting a simple shepherd service--i.e., the type
for a service that extends SHEPHERD-ROOT-SERVICE-TYPE and nothing else."
(service-type
(name service-name)
(extensions
(list (service-extension shepherd-root-service-type
(compose list proc))))))
(define %default-imported-modules
;; Default set of modules imported for a service's consumption.
'((guix build utils)
(guix build syscalls)))
(define %default-modules
;; Default set of modules visible in a service's file.
`((shepherd service)
(oop goops)
(guix build utils)
(guix build syscalls)))
(define-record-type* <shepherd-service>
shepherd-service make-shepherd-service
shepherd-service?
(documentation shepherd-service-documentation ;string
(default "[No documentation.]"))
(provision shepherd-service-provision) ;list of symbols
(requirement shepherd-service-requirement ;list of symbols
(default '()))
(respawn? shepherd-service-respawn? ;Boolean
(default #t))
(start shepherd-service-start) ;g-expression (procedure)
(stop shepherd-service-stop ;g-expression (procedure)
(default #~(const #f)))
(auto-start? shepherd-service-auto-start? ;Boolean
(default #t))
(modules shepherd-service-modules ;list of module names
(default %default-modules)))
(define (shepherd-service-canonical-name service)
"Return the 'canonical name' of SERVICE."
(first (shepherd-service-provision service)))
(define (assert-valid-graph services)
"Raise an error if SERVICES does not define a valid shepherd service graph,
for instance if a service requires a nonexistent service, or if more than one
service uses a given name.
These are constraints that shepherd's 'register-service' verifies but we'd
better verify them here statically than wait until PID 1 halts with an
assertion failure."
(define provisions
;; The set of provisions (symbols). Bail out if a symbol is given more
;; than once.
(fold (lambda (service set)
(define (assert-unique symbol)
(when (set-contains? set symbol)
(raise (condition
(&message
(message
(format #f (_ "service '~a' provided more than once")
symbol)))))))
(for-each assert-unique (shepherd-service-provision service))
(fold set-insert set (shepherd-service-provision service)))
(setq 'shepherd)
services))
(define (assert-satisfied-requirements service)
;; Bail out if the requirements of SERVICE aren't satisfied.
(for-each (lambda (requirement)
(unless (set-contains? provisions requirement)
(raise (condition
(&message
(message
(format #f (_ "service '~a' requires '~a', \
which is not provided by any service")
(match (shepherd-service-provision service)
((head . _) head)
(_ service))
requirement)))))))
(shepherd-service-requirement service)))
(for-each assert-satisfied-requirements services))
(define (shepherd-service-file-name service)
"Return the file name where the initialization code for SERVICE is to be
stored."
(let ((provisions (string-join (map symbol->string
(shepherd-service-provision service)))))
(string-append "shepherd-"
(string-map (match-lambda
(#\/ #\-)
(chr chr))
provisions)
".scm")))
(define (shepherd-service-file service)
"Return a file defining SERVICE."
(gexp->file (shepherd-service-file-name service)
(with-imported-modules %default-imported-modules
#~(begin
(use-modules #$@(shepherd-service-modules service))
(make <service>
#:docstring '#$(shepherd-service-documentation service)
#:provides '#$(shepherd-service-provision service)
#:requires '#$(shepherd-service-requirement service)
#:respawn? '#$(shepherd-service-respawn? service)
#:start #$(shepherd-service-start service)
#:stop #$(shepherd-service-stop service))))))
(define (shepherd-configuration-file services)
"Return the shepherd configuration file for SERVICES."
(assert-valid-graph services)
(mlet %store-monad ((files (mapm %store-monad
shepherd-service-file services)))
(define config
#~(begin
(use-modules (srfi srfi-34)
(system repl error-handling))
;; Arrange to spawn a REPL if something goes wrong. This is better
;; than a kernel panic.
(call-with-error-handling
(lambda ()
(apply register-services (map primitive-load '#$files))
;; guix-daemon 0.6 aborts if 'PATH' is undefined, so work around
;; it.
(setenv "PATH" "/run/current-system/profile/bin")
(format #t "starting services...~%")
(for-each (lambda (service)
;; In the Shepherd 0.3 the 'start' method can raise
;; '&action-runtime-error' if it fails, so protect
;; against it. (XXX: 'action-runtime-error?' is not
;; exported is 0.3, hence 'service-error?'.)
(guard (c ((service-error? c)
(format (current-error-port)
"failed to start service '~a'~%"
service)))
(start service)))
'#$(append-map shepherd-service-provision
(filter shepherd-service-auto-start?
services)))))))
(gexp->file "shepherd.conf" config)))
(define (shepherd-service-back-edges services)
"Return a procedure that, when given a <shepherd-service> from SERVICES,
returns the list of <shepherd-service> that depend on it."
(define provision->service
(let ((services (fold (lambda (service result)
(fold (cut vhash-consq <> service <>)
result
(shepherd-service-provision service)))
vlist-null
services)))
(lambda (name)
(match (vhash-assq name services)
((_ . service) service)
(#f #f)))))
(define edges
(fold (lambda (service edges)
(fold (lambda (requirement edges)
(vhash-consq (provision->service requirement) service
edges))
edges
(shepherd-service-requirement service)))
vlist-null
services))
(lambda (service)
(vhash-foldq* cons '() service edges)))
;;; shepherd.scm ends here