guix-devel/gnu/system/linux-container.scm

127 lines
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Scheme

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@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 system linux-container)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:use-module (guix config)
#:use-module (guix store)
#:use-module (guix gexp)
#:use-module (guix derivations)
#:use-module (guix monads)
#:use-module (gnu build linux-container)
#:use-module (gnu services)
#:use-module (gnu system)
#:use-module (gnu system file-systems)
#:export (mapping->file-system
system-container
containerized-operating-system
container-script))
(define (mapping->file-system mapping)
"Return a file system that realizes MAPPING."
(match mapping
(($ <file-system-mapping> source target writable?)
(file-system
(mount-point target)
(device source)
(type "none")
(flags (if writable?
'(bind-mount)
'(bind-mount read-only)))
(check? #f)
(create-mount-point? #t)))))
(define (system-container os)
"Return a derivation that builds OS as a Linux container."
(mlet* %store-monad
((profile (operating-system-profile os))
(etc -> (operating-system-etc-directory os))
(boot (operating-system-boot-script os #:container? #t))
(locale (operating-system-locale-directory os)))
(lower-object
(file-union "system-container"
`(("boot" ,#~#$boot)
("profile" ,#~#$profile)
("locale" ,#~#$locale)
("etc" ,#~#$etc))))))
(define (containerized-operating-system os mappings)
"Return an operating system based on OS for use in a Linux container
environment. MAPPINGS is a list of <file-system-mapping> to realize in the
containerized OS."
(define user-file-systems
(remove (lambda (fs)
(let ((target (file-system-mount-point fs))
(source (file-system-device fs)))
(or (string=? target (%store-prefix))
(string=? target "/")
(string-prefix? "/dev/" source)
(string-prefix? "/dev" target)
(string-prefix? "/sys" target))))
(operating-system-file-systems os)))
(define (mapping->fs fs)
(file-system (inherit (mapping->file-system fs))
(needed-for-boot? #t)))
(operating-system (inherit os)
(swap-devices '()) ; disable swap
(file-systems (append (map mapping->fs (cons %store-mapping mappings))
%container-file-systems
user-file-systems))))
(define* (container-script os #:key (mappings '()))
"Return a derivation of a script that runs OS as a Linux container.
MAPPINGS is a list of <file-system> objects that specify the files/directories
that will be shared with the host system."
(let* ((os (containerized-operating-system os mappings))
(file-systems (filter file-system-needed-for-boot?
(operating-system-file-systems os)))
(specs (map file-system->spec file-systems)))
(mlet* %store-monad ((os-drv (system-container os)))
(define script
#~(begin
(use-modules (gnu build linux-container)
(guix build utils))
(call-with-container '#$specs
(lambda ()
(setenv "HOME" "/root")
(setenv "TMPDIR" "/tmp")
(setenv "GUIX_NEW_SYSTEM" #$os-drv)
(for-each mkdir-p '("/run" "/bin" "/etc" "/home" "/var"))
(primitive-load (string-append #$os-drv "/boot")))
;; A range of 65536 uid/gids is used to cover 16 bits worth of
;; users and groups, which is sufficient for most cases.
;;
;; See: http://www.freedesktop.org/software/systemd/man/systemd-nspawn.html#--private-users=
#:host-uids 65536)))
(gexp->script "run-container" script
#:modules '((ice-9 match)
(srfi srfi-98)
(guix config)
(guix utils)
(guix build utils)
(guix build syscalls)
(gnu build file-systems)
(gnu build linux-container))))))