554 lines
22 KiB
Scheme
554 lines
22 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014, 2015, 2016, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2017 Clément Lassieur <clement@lassieur.org>
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;;; Copyright © 2018 Carlo Zancanaro <carlo@zancanaro.id.au>
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;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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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 shepherd)
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#:use-module (guix ui)
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#:use-module (guix sets)
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#:use-module (guix gexp)
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#:use-module (guix store)
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#:use-module (guix records)
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#:use-module (guix derivations) ;imported-modules, etc.
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#:use-module (guix utils)
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#:use-module (gnu services)
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#:use-module (gnu services herd)
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#:use-module (gnu packages admin)
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#:use-module (ice-9 match)
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#:use-module (ice-9 vlist)
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#:use-module (srfi srfi-1)
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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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#:export (shepherd-root-service-type
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%shepherd-root-service
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shepherd-service-type
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shepherd-service
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shepherd-service?
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shepherd-service-documentation
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shepherd-service-provision
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shepherd-service-canonical-name
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shepherd-service-requirement
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shepherd-service-one-shot?
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shepherd-service-respawn?
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shepherd-service-start
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shepherd-service-stop
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shepherd-service-auto-start?
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shepherd-service-modules
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shepherd-action
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shepherd-action?
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shepherd-action-name
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shepherd-action-documentation
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shepherd-action-procedure
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%default-modules
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shepherd-service-file
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shepherd-service-lookup-procedure
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shepherd-service-back-edges
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shepherd-service-upgrade
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user-processes-service-type))
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;;; Commentary:
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;;;
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;;; Instantiating system services as a shepherd configuration file.
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;;;
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;;; Code:
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(define (shepherd-boot-gexp services)
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#~(begin
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;; Keep track of the booted system.
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(false-if-exception (delete-file "/run/booted-system"))
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(symlink (readlink "/run/current-system")
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"/run/booted-system")
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;; Close any remaining open file descriptors to be on the safe
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;; side. This must be the very last thing we do, because
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;; Guile has internal FDs such as 'sleep_pipe' that need to be
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;; alive.
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(let loop ((fd 3))
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(when (< fd 1024)
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(false-if-exception (close-fdes fd))
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(loop (+ 1 fd))))
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;; Start shepherd.
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(execl #$(file-append shepherd "/bin/shepherd")
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"shepherd" "--config"
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#$(shepherd-configuration-file services))))
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(define shepherd-root-service-type
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(service-type
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(name 'shepherd-root)
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;; Extending the root shepherd service (aka. PID 1) happens by
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;; concatenating the list of services provided by the extensions.
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(compose concatenate)
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(extend append)
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(extensions (list (service-extension boot-service-type
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shepherd-boot-gexp)
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(service-extension profile-service-type
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(const (list shepherd)))))
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(description
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"Run the GNU Shepherd as PID 1---i.e., the operating system's first
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process. The Shepherd takes care of managing services such as daemons by
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ensuring they are started and stopped in the right order.")))
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(define %shepherd-root-service
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;; The root shepherd service, aka. PID 1. Its parameter is a list of
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;; <shepherd-service> objects.
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(service shepherd-root-service-type '()))
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(define-syntax shepherd-service-type
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(syntax-rules ()
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"Return a <service-type> denoting a simple shepherd service--i.e., the type
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for a service that extends SHEPHERD-ROOT-SERVICE-TYPE and nothing else. When
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DEFAULT is given, use it as the service's default value."
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((_ service-name proc default)
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(service-type
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(name service-name)
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(extensions
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(list (service-extension shepherd-root-service-type
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(compose list proc))))
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(default-value default)))
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((_ service-name proc)
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(service-type
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(name service-name)
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(extensions
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(list (service-extension shepherd-root-service-type
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(compose list proc))))))))
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(define %default-imported-modules
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;; Default set of modules imported for a service's consumption.
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'((guix build utils)
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(guix build syscalls)))
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(define %default-modules
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;; Default set of modules visible in a service's file.
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`((shepherd service)
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(oop goops)
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((guix build utils) #:hide (delete))
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(guix build syscalls)))
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(define-record-type* <shepherd-service>
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shepherd-service make-shepherd-service
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shepherd-service?
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(documentation shepherd-service-documentation ;string
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(default "[No documentation.]"))
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(provision shepherd-service-provision) ;list of symbols
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(requirement shepherd-service-requirement ;list of symbols
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(default '()))
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(one-shot? shepherd-service-one-shot? ;Boolean
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(default #f))
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(respawn? shepherd-service-respawn? ;Boolean
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(default #t))
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(start shepherd-service-start) ;g-expression (procedure)
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(stop shepherd-service-stop ;g-expression (procedure)
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(default #~(const #f)))
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(actions shepherd-service-actions ;list of <shepherd-action>
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(default '()))
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(auto-start? shepherd-service-auto-start? ;Boolean
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(default #t))
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(modules shepherd-service-modules ;list of module names
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(default %default-modules)))
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(define-record-type* <shepherd-action>
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shepherd-action make-shepherd-action
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shepherd-action?
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(name shepherd-action-name) ;symbol
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(procedure shepherd-action-procedure) ;gexp
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(documentation shepherd-action-documentation)) ;string
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(define (shepherd-service-canonical-name service)
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"Return the 'canonical name' of SERVICE."
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(first (shepherd-service-provision service)))
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(define (assert-valid-graph services)
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"Raise an error if SERVICES does not define a valid shepherd service graph,
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for instance if a service requires a nonexistent service, or if more than one
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service uses a given name.
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These are constraints that shepherd's 'register-service' verifies but we'd
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better verify them here statically than wait until PID 1 halts with an
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assertion failure."
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(define provisions
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;; The set of provisions (symbols). Bail out if a symbol is given more
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;; than once.
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(fold (lambda (service set)
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(define (assert-unique symbol)
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(when (set-contains? set symbol)
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(raise (condition
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(&message
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(message
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(format #f (G_ "service '~a' provided more than once")
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symbol)))))))
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(for-each assert-unique (shepherd-service-provision service))
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(fold set-insert set (shepherd-service-provision service)))
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(setq 'shepherd)
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services))
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(define (assert-satisfied-requirements service)
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;; Bail out if the requirements of SERVICE aren't satisfied.
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(for-each (lambda (requirement)
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(unless (set-contains? provisions requirement)
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(raise (condition
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(&message
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(message
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(format #f (G_ "service '~a' requires '~a', \
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which is not provided by any service")
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(match (shepherd-service-provision service)
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((head . _) head)
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(_ service))
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requirement)))))))
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(shepherd-service-requirement service)))
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(for-each assert-satisfied-requirements services))
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(define (shepherd-service-file-name service)
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"Return the file name where the initialization code for SERVICE is to be
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stored."
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(let ((provisions (string-join (map symbol->string
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(shepherd-service-provision service)))))
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(string-append "shepherd-"
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(string-map (match-lambda
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(#\/ #\-)
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(#\ #\-)
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(chr chr))
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provisions)
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".scm")))
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(define (shepherd-service-file service)
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"Return a file defining SERVICE."
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(scheme-file (shepherd-service-file-name service)
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(with-imported-modules %default-imported-modules
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#~(begin
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(use-modules #$@(shepherd-service-modules service))
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(make <service>
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#:docstring '#$(shepherd-service-documentation service)
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#:provides '#$(shepherd-service-provision service)
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#:requires '#$(shepherd-service-requirement service)
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;; The 'one-shot?' slot is new in Shepherd 0.6.0.
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;; Older versions ignore it.
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#:one-shot? '#$(shepherd-service-one-shot? service)
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#:respawn? '#$(shepherd-service-respawn? service)
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#:start #$(shepherd-service-start service)
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#:stop #$(shepherd-service-stop service)
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#:actions
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(make-actions
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#$@(map (match-lambda
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(($ <shepherd-action> name proc doc)
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#~(#$name #$doc #$proc)))
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(shepherd-service-actions service))))))))
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(define (scm->go file)
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"Compile FILE, which contains code to be loaded by shepherd's config file,
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and return the resulting '.go' file."
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(let-system (system target)
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(with-extensions (list shepherd)
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(computed-file (string-append (basename (scheme-file-name file) ".scm")
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".go")
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#~(begin
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(use-modules (system base compile)
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(system base target))
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;; Do the same as the Shepherd's 'load-in-user-module'.
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(let ((env (make-fresh-user-module)))
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(module-use! env (resolve-interface '(oop goops)))
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(module-use! env (resolve-interface '(shepherd service)))
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(with-target #$(or target #~%host-type)
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(lambda _
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(compile-file #$file #:output-file #$output
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#:env env)))))
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;; It's faster to build locally than to download.
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#:options '(#:local-build? #t
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#:substitutable? #f)))))
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(define (shepherd-configuration-file services)
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"Return the shepherd configuration file for SERVICES."
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(assert-valid-graph services)
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(let ((files (map shepherd-service-file services)))
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(define config
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#~(begin
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(use-modules (srfi srfi-34)
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(system repl error-handling))
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;; Specify the default environment visible to all the services.
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;; Without this statement, all the environment variables of PID 1
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;; are inherited by child services.
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(default-environment-variables
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'("PATH=/run/current-system/profile/bin"))
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;; Booting off a DVD, especially on a slow machine, can make
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;; everything slow. Thus, increase the timeout compared to the
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;; default 5s in the Shepherd 0.7.0. See
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;; <https://bugs.gnu.org/40572>.
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(default-pid-file-timeout 30)
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;; Arrange to spawn a REPL if something goes wrong. This is better
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;; than a kernel panic.
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(call-with-error-handling
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(lambda ()
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(apply register-services
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(parameterize ((current-warning-port
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(%make-void-port "w")))
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(map load-compiled '#$(map scm->go files))))))
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(format #t "starting services...~%")
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(for-each (lambda (service)
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;; In the Shepherd 0.3 the 'start' method can raise
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;; '&action-runtime-error' if it fails, so protect
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;; against it. (XXX: 'action-runtime-error?' is not
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;; exported is 0.3, hence 'service-error?'.)
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(guard (c ((service-error? c)
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(format (current-error-port)
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"failed to start service '~a'~%"
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service)))
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(start service)))
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'#$(append-map shepherd-service-provision
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(filter shepherd-service-auto-start?
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services)))
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;; Hang up stdin. At this point, we assume that 'start' methods
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;; that required user interaction on the console (e.g.,
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;; 'cryptsetup open' invocations, post-fsck emergency REPL) have
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;; completed. User interaction becomes impossible after this
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;; call; this avoids situations where services wrongfully lead
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;; PID 1 to read from stdin (the console), which users may not
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;; have access to (see <https://bugs.gnu.org/23697>).
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(redirect-port (open-input-file "/dev/null")
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(current-input-port))))
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(scheme-file "shepherd.conf" config)))
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(define* (shepherd-service-lookup-procedure services
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#:optional
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(provision
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shepherd-service-provision))
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"Return a procedure that, when passed a symbol, return the item among
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SERVICES that provides this symbol. PROVISION must be a one-argument
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procedure that takes a service and returns the list of symbols it provides."
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(let ((services (fold (lambda (service result)
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(fold (cut vhash-consq <> service <>)
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result
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(provision service)))
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vlist-null
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services)))
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(lambda (name)
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(match (vhash-assq name services)
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((_ . service) service)
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(#f #f)))))
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(define* (shepherd-service-back-edges services
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#:key
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(provision shepherd-service-provision)
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(requirement shepherd-service-requirement))
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"Return a procedure that, when given a <shepherd-service> from SERVICES,
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returns the list of <shepherd-service> that depend on it.
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Use PROVISION and REQUIREMENT as one-argument procedures that return the
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symbols provided/required by a service."
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(define provision->service
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(shepherd-service-lookup-procedure services provision))
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(define edges
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(fold (lambda (service edges)
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(fold (lambda (requirement edges)
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(vhash-consq (provision->service requirement) service
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edges))
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edges
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(requirement service)))
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vlist-null
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services))
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(lambda (service)
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(vhash-foldq* cons '() service edges)))
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(define (shepherd-service-upgrade live target)
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"Return two values: the subset of LIVE (a list of <live-service>) that needs
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to be unloaded, and the subset of TARGET (a list of <shepherd-service>) that
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need to be restarted to complete their upgrade."
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(define (essential? service)
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(memq (first (live-service-provision service))
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'(root shepherd)))
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(define lookup-target
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(shepherd-service-lookup-procedure target
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shepherd-service-provision))
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(define lookup-live
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(shepherd-service-lookup-procedure live
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live-service-provision))
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(define (running? service)
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(and=> (lookup-live (shepherd-service-canonical-name service))
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live-service-running))
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(define live-service-dependents
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(shepherd-service-back-edges live
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#:provision live-service-provision
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#:requirement live-service-requirement))
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(define (obsolete? service)
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(match (lookup-target (first (live-service-provision service)))
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(#f (every obsolete? (live-service-dependents service)))
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(_ #f)))
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(define to-restart
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;; Restart services that are currently running.
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(filter running? target))
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(define to-unload
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;; Unload services that are no longer required.
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(remove essential? (filter obsolete? live)))
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(values to-unload to-restart))
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;;;
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;;; User processes.
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;;;
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(define %do-not-kill-file
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;; Name of the file listing PIDs of processes that must survive when halting
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;; the system. Typical example is user-space file systems.
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"/etc/shepherd/do-not-kill")
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(define (user-processes-shepherd-service requirements)
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"Return the 'user-processes' Shepherd service with dependencies on
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REQUIREMENTS (a list of service names).
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This is a synchronization point used to make sure user processes and daemons
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get started only after crucial initial services have been started---file
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system mounts, etc. This is similar to the 'sysvinit' target in systemd."
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(define grace-delay
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;; Delay after sending SIGTERM and before sending SIGKILL.
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4)
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(list (shepherd-service
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(documentation "When stopped, terminate all user processes.")
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(provision '(user-processes))
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(requirement requirements)
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(start #~(const #t))
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(stop #~(lambda _
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(define (kill-except omit signal)
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;; Kill all the processes with SIGNAL except those listed
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;; in OMIT and the current process.
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(let ((omit (cons (getpid) omit)))
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(for-each (lambda (pid)
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(unless (memv pid omit)
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(false-if-exception
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(kill pid signal))))
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(processes))))
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(define omitted-pids
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;; List of PIDs that must not be killed.
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(if (file-exists? #$%do-not-kill-file)
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(map string->number
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(call-with-input-file #$%do-not-kill-file
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(compose string-tokenize
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(@ (ice-9 rdelim) read-string))))
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'()))
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(define (now)
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(car (gettimeofday)))
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(define (sleep* n)
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;; Really sleep N seconds.
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;; Work around <http://bugs.gnu.org/19581>.
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(define start (now))
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(let loop ((elapsed 0))
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(when (> n elapsed)
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(sleep (- n elapsed))
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(loop (- (now) start)))))
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(define lset= (@ (srfi srfi-1) lset=))
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(display "sending all processes the TERM signal\n")
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(if (null? omitted-pids)
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(begin
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;; Easy: terminate all of them.
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(kill -1 SIGTERM)
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(sleep* #$grace-delay)
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(kill -1 SIGKILL))
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(begin
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;; Kill them all except OMITTED-PIDS. XXX: We would
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;; like to (kill -1 SIGSTOP) to get a fixed list of
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;; processes, like 'killall5' does, but that seems
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;; unreliable.
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(kill-except omitted-pids SIGTERM)
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(sleep* #$grace-delay)
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(kill-except omitted-pids SIGKILL)
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||
(delete-file #$%do-not-kill-file)))
|
||
|
||
(let wait ()
|
||
;; Reap children, if any, so that we don't end up with
|
||
;; zombies and enter an infinite loop.
|
||
(let reap-children ()
|
||
(define result
|
||
(false-if-exception
|
||
(waitpid WAIT_ANY (if (null? omitted-pids)
|
||
0
|
||
WNOHANG))))
|
||
|
||
(when (and (pair? result)
|
||
(not (zero? (car result))))
|
||
(reap-children)))
|
||
|
||
(let ((pids (processes)))
|
||
(unless (lset= = pids (cons 1 omitted-pids))
|
||
(format #t "waiting for process termination\
|
||
(processes left: ~s)~%"
|
||
pids)
|
||
(sleep* 2)
|
||
(wait))))
|
||
|
||
(display "all processes have been terminated\n")
|
||
#f))
|
||
(respawn? #f))))
|
||
|
||
(define user-processes-service-type
|
||
(service-type
|
||
(name 'user-processes)
|
||
(extensions (list (service-extension shepherd-root-service-type
|
||
user-processes-shepherd-service)))
|
||
(compose concatenate)
|
||
(extend append)
|
||
|
||
;; The value is the list of Shepherd services 'user-processes' depends on.
|
||
;; Extensions can add new services to this list.
|
||
(default-value '())
|
||
|
||
(description "The @code{user-processes} service is responsible for
|
||
terminating all the processes so that the root file system can be re-mounted
|
||
read-only, just before rebooting/halting. Processes still running after a few
|
||
seconds after @code{SIGTERM} has been sent are terminated with
|
||
@code{SIGKILL}.")))
|
||
|
||
;;; shepherd.scm ends here
|