5627bfe45c
* gnu/system/linux-container.scm (%nscd-container-caches): New variable. (containerized-operating-system): Instantiate nscd-service with smaller caches and add it to the generated operating-system, replacing any nscd-service specified by the caller. * gnu/system/file-systems.scm: (%network-file-mappings): Remove "/var/run/nscd". Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
292 lines
13 KiB
Scheme
292 lines
13 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2015 David Thompson <davet@gnu.org>
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;;; Copyright © 2016, 2017, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2019 Arun Isaac <arunisaac@systemreboot.net>
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;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
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;;; Copyright © 2020 Google LLC
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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 system linux-container)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-1)
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#:use-module (guix config)
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#:use-module (guix store)
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#:use-module (guix gexp)
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#:use-module (guix derivations)
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#:use-module (guix monads)
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#:use-module (guix modules)
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#:use-module (gnu build linux-container)
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#:use-module (gnu services)
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#:use-module (gnu services base)
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#:use-module (gnu services networking)
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#:use-module (gnu services shepherd)
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#:use-module (gnu system)
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#:use-module (gnu system file-systems)
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#:export (system-container
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containerized-operating-system
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container-script
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eval/container))
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(define* (container-essential-services os #:key shared-network?)
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"Return a list of essential services corresponding to OS, a
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non-containerized OS. This procedure essentially strips essential services
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from OS that are needed on the bare metal and not in a container."
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(define base
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(remove (lambda (service)
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(memq (service-kind service)
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(list (service-kind %linux-bare-metal-service)
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firmware-service-type
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system-service-type)))
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(operating-system-default-essential-services os)))
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(cons (service system-service-type
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`(("locale" ,(operating-system-locale-directory os))))
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;; If network is to be shared with the host, remove network
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;; configuration files from etc-service.
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(if shared-network?
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(modify-services base
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(etc-service-type
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files => (remove
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(match-lambda
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((filename _)
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(member filename
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(map basename %network-configuration-files))))
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files)))
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base)))
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(define dummy-networking-service-type
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(shepherd-service-type
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'dummy-networking
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(const (shepherd-service
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(documentation "Provide loopback and networking without actually
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doing anything.")
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(provision '(loopback networking))
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(start #~(const #t))))
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#f))
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(define %nscd-container-caches
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;; Similar to %nscd-default-caches but with smaller cache sizes. This allows
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;; many containers to coexist on the same machine without exhausting RAM.
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(map (lambda (cache)
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(nscd-cache
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(inherit cache)
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(max-database-size (expt 2 18)))) ;256KiB
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%nscd-default-caches))
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(define* (containerized-operating-system os mappings
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#:key
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shared-network?
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(extra-file-systems '()))
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"Return an operating system based on OS for use in a Linux container
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environment. MAPPINGS is a list of <file-system-mapping> to realize in the
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containerized OS. EXTRA-FILE-SYSTEMS is a list of file systems to add to OS."
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(define user-file-systems
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(remove (lambda (fs)
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(let ((target (file-system-mount-point fs))
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(source (file-system-device fs)))
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(or (string=? target (%store-prefix))
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(string=? target "/")
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(and (string? source)
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(string-prefix? "/dev/" source))
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(string-prefix? "/dev/" target)
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(string-prefix? "/sys/" target))))
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(operating-system-file-systems os)))
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(define (mapping->fs fs)
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(file-system (inherit (file-system-mapping->bind-mount fs))
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(needed-for-boot? #t)))
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(define services-to-drop
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;; Service types to filter from the original operating-system. Some of
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;; these make no sense in a container (e.g., those that access
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;; /dev/tty[0-9]), while others just need to be reinstantiated with
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;; different configs that are better suited to containers.
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(append (list console-font-service-type
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mingetty-service-type
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agetty-service-type
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;; Reinstantiated below with smaller caches.
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nscd-service-type)
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(if shared-network?
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;; Replace these with dummy-networking-service-type below.
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(list
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static-networking-service-type
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dhcp-client-service-type
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network-manager-service-type
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connman-service-type
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wicd-service-type)
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(list))))
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(define services-to-add
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(append
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;; Many Guix services depend on a 'networking' shepherd
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;; service, so make sure to provide a dummy 'networking'
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;; service when we are sure that networking is already set up
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;; in the host and can be used. That prevents double setup.
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(if shared-network?
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(list (service dummy-networking-service-type))
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'())
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(list
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(nscd-service (nscd-configuration
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(caches %nscd-container-caches))))))
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(operating-system
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(inherit os)
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(swap-devices '()) ; disable swap
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(essential-services (container-essential-services
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this-operating-system
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#:shared-network? shared-network?))
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(services (append (remove (lambda (service)
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(memq (service-kind service)
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services-to-drop))
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(operating-system-user-services os))
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services-to-add))
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(file-systems (append (map mapping->fs
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(if shared-network?
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(append %network-file-mappings mappings)
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mappings))
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extra-file-systems
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user-file-systems
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;; Provide a dummy root file system so we can create
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;; a 'boot-parameters' file.
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(list (file-system
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(mount-point "/")
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(device "nothing")
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(type "dummy")))))))
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(define* (container-script os #:key (mappings '()) shared-network?)
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"Return a derivation of a script that runs OS as a Linux container.
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MAPPINGS is a list of <file-system> objects that specify the files/directories
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that will be shared with the host system."
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(define (mountable-file-system? file-system)
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;; Return #t if FILE-SYSTEM should be mounted in the container.
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(and (not (string=? "/" (file-system-mount-point file-system)))
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(file-system-needed-for-boot? file-system)))
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(define (os-file-system-specs os)
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(map file-system->spec
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(filter mountable-file-system?
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(operating-system-file-systems os))))
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(let* ((os (containerized-operating-system
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os (cons %store-mapping mappings)
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#:shared-network? shared-network?
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#:extra-file-systems %container-file-systems))
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(specs (os-file-system-specs os)))
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(define script
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(with-imported-modules (source-module-closure
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'((guix build utils)
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(gnu build linux-container)
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(guix i18n)
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(guix diagnostics)))
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#~(begin
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(use-modules (gnu build linux-container)
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(gnu system file-systems) ;spec->file-system
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(guix build utils)
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(guix i18n)
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(guix diagnostics)
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(srfi srfi-1))
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(define file-systems
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(filter-map (lambda (spec)
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(let* ((fs (spec->file-system spec))
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(flags (file-system-flags fs)))
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(and (or (not (memq 'bind-mount flags))
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(file-exists? (file-system-device fs)))
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fs)))
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'#$specs))
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(define (explain pid)
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;; XXX: We can't quite call 'bindtextdomain' so there's actually
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;; no i18n.
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;; XXX: Should we really give both options? 'guix container exec'
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;; is a more verbose command. Hard to fail to enter the container
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;; when we list two options.
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(info (G_ "system container is running as PID ~a~%") pid)
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(info (G_ "Run 'sudo guix container exec ~a /run/current-system/profile/bin/bash --login'\n")
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pid)
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(info (G_ "or run 'sudo nsenter -a -t ~a' to get a shell into it.~%") pid)
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(newline (guix-warning-port)))
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(call-with-container file-systems
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(lambda ()
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(setenv "HOME" "/root")
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(setenv "TMPDIR" "/tmp")
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(setenv "GUIX_NEW_SYSTEM" #$os)
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(for-each mkdir-p '("/run" "/bin" "/etc" "/home" "/var"))
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(primitive-load (string-append #$os "/boot")))
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;; A range of 65536 uid/gids is used to cover 16 bits worth of
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;; users and groups, which is sufficient for most cases.
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;;
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;; See: http://www.freedesktop.org/software/systemd/man/systemd-nspawn.html#--private-users=
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#:host-uids 65536
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#:namespaces (if #$shared-network?
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(delq 'net %namespaces)
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%namespaces)
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#:process-spawned-hook explain))))
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(gexp->script "run-container" script)))
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(define* (eval/container exp
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#:key
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(mappings '())
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(namespaces %namespaces))
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"Evaluate EXP, a gexp, in a new process executing in separate namespaces as
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listed in NAMESPACES. Add MAPPINGS, a list of <file-system-mapping>, to the
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set of directories visible in the process's mount namespace. Return the
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process' exit status as a monadic value.
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This is useful to implement processes that, unlike derivations, are not
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entirely pure and need to access the outside world or to perform side
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effects."
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(mlet %store-monad ((lowered (lower-gexp exp)))
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(define inputs
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(cons (lowered-gexp-guile lowered)
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(lowered-gexp-inputs lowered)))
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(define items
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(append (append-map derivation-input-output-paths inputs)
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(lowered-gexp-sources lowered)))
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(mbegin %store-monad
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(built-derivations inputs)
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(mlet %store-monad ((closure ((store-lift requisites) items)))
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(return (call-with-container (map file-system-mapping->bind-mount
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(append (map (lambda (item)
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(file-system-mapping
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(source item)
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(target source)))
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closure)
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mappings))
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(lambda ()
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(apply execl
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(string-append (derivation-input-output-path
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(lowered-gexp-guile lowered))
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"/bin/guile")
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"guile"
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(append (append-map (lambda (directory)
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`("-L" ,directory))
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(lowered-gexp-load-path lowered))
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(append-map (lambda (directory)
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`("-C" ,directory))
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(lowered-gexp-load-compiled-path
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lowered))
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(list "-c"
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(object->string
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(lowered-gexp-sexp lowered))))))))))))
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