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linux-container: Support container network sharing.

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* gnu/system/linux-container.scm (container-essential-services): If network is
to be shared with the host, remove network configuration files from etc
service.
(containerized-operating-system): If network is to be shared with the host,
remove nscd service and map host's /var/run/nscd if it exists.
(container-script): If network is to be shared with the host, do not create
network namespace.
* guix/scripts/system.scm (system-derivation-for-action): Add
#:container-shared-network? argument.
(perform-action): Add #:container-shared-network? argument.
(show-help): Add "-N, --network" help information.
(%options): Add network option.
(process-action): Call perform-action with #container-shared-network? argument.
* doc/guix.texi (Invoking guix system): Document the "-N, --network" option.

Co-authored-by: Christopher Baines <mail@cbaines.net>
This commit is contained in:
Arun Isaac 2019-05-10 16:56:16 +05:30
parent 1bba3e8ca8
commit b33454ae0b
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GPG key ID: 2E25EE8B61802BB3
3 changed files with 75 additions and 13 deletions
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5
doc/guix.texi
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@ -24587,6 +24587,11 @@ When this option is omitted, @command{guix system} computes an estimate
of the image size as a function of the size of the system declared in
@var{file}.
@item --network
@itemx -N
For the @code{container} action, allow containers to access the host network,
that is, do not create a network namespace.
@item --root=@var{file}
@itemx -r @var{file}
Make @var{file} a symlink to the result, and register it as a garbage

61
gnu/system/linux-container.scm
View file

@ -1,6 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2016, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2019 Arun Isaac <arunisaac@systemreboot.net>
;;;
;;; This file is part of GNU Guix.
;;;
@ -35,7 +36,7 @@
containerized-operating-system
container-script))
(define (container-essential-services os)
(define* (container-essential-services os #:key shared-network?)
"Return a list of essential services corresponding to OS, a
non-containerized OS. This procedure essentially strips essential services
from OS that are needed on the bare metal and not in a container."
@ -51,9 +52,20 @@ from OS that are needed on the bare metal and not in a container."
(let ((locale (operating-system-locale-directory os)))
(with-monad %store-monad
(return `(("locale" ,locale))))))
base))
;; If network is to be shared with the host, remove network
;; configuration files from etc-service.
(if shared-network?
(modify-services base
(etc-service-type
files => (remove
(match-lambda
((filename _)
(member filename
(map basename %network-configuration-files))))
files)))
base)))
(define (containerized-operating-system os mappings)
(define* (containerized-operating-system os mappings #:key shared-network?)
"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."
@ -76,27 +88,53 @@ containerized OS."
(define useless-services
;; Services that make no sense in a container. Those that attempt to
;; access /dev/tty[0-9] in particular cannot work in a container.
(list console-font-service-type
(append (list console-font-service-type
mingetty-service-type
agetty-service-type))
agetty-service-type)
;; Remove nscd service if network is shared with the host.
(if shared-network?
(list nscd-service-type)
(list))))
(define shared-network-file-mappings
;; Files to map if network is to be shared with the host
(append %network-file-mappings
(let ((nscd-run-directory "/var/run/nscd"))
(if (file-exists? nscd-run-directory)
(list (file-system-mapping
(source nscd-run-directory)
(target nscd-run-directory)))
(list)))))
;; (write shared-network-file-mappings)
;; (newline)
(operating-system
(inherit os)
(swap-devices '()) ; disable swap
(essential-services (container-essential-services os))
(essential-services (container-essential-services
os #:shared-network? shared-network?))
(services (remove (lambda (service)
(memq (service-kind service)
useless-services))
(operating-system-user-services os)))
(file-systems (append (map mapping->fs (cons %store-mapping mappings))
(file-systems (append (map mapping->fs
(cons %store-mapping
(append mappings
(if shared-network?
shared-network-file-mappings
(list)))))
%container-file-systems
user-file-systems))))
(define* (container-script os #:key (mappings '()))
(define* (container-script os #:key (mappings '()) shared-network?)
"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))
(let* ((os (containerized-operating-system
os
mappings
#:shared-network? shared-network?))
(file-systems (filter file-system-needed-for-boot?
(operating-system-file-systems os)))
(specs (map file-system->spec file-systems)))
@ -121,6 +159,9 @@ that will be shared with the host system."
;; 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))))
#:host-uids 65536
#:namespaces (if #$shared-network?
(delq 'net %namespaces)
%namespaces)))))
(gexp->script "run-container" script)))

20
guix/scripts/system.scm
View file

@ -4,6 +4,7 @@
;;; Copyright © 2016, 2017, 2018 Chris Marusich <cmmarusich@gmail.com>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2018 Ricardo Wurmus <rekado@elephly.net>
;;; Copyright © 2019 Christopher Baines <mail@cbaines.net>
;;;
;;; This file is part of GNU Guix.
;;;
@ -756,13 +757,17 @@ checking this by themselves in their 'check' procedure."
(define* (system-derivation-for-action os action
#:key image-size file-system-type
full-boot? mappings)
full-boot? container-shared-network?
mappings)
"Return as a monadic value the derivation for OS according to ACTION."
(case action
((build init reconfigure)
(operating-system-derivation os))
((container)
(container-script os #:mappings mappings))
(container-script
os
#:mappings mappings
#:shared-network? container-shared-network?))
((vm-image)
(system-qemu-image os #:disk-image-size image-size))
((vm)
@ -826,6 +831,7 @@ and TARGET arguments."
dry-run? derivations-only?
use-substitutes? bootloader-target target
image-size file-system-type full-boot?
container-shared-network?
(mappings '())
(gc-root #f))
"Perform ACTION for OS. INSTALL-BOOTLOADER? specifies whether to install
@ -834,6 +840,8 @@ target root directory; IMAGE-SIZE is the size of the image to be built, for
the 'vm-image' and 'disk-image' actions. The root file system is created as a
FILE-SYSTEM-TYPE file system. FULL-BOOT? is used for the 'vm' action; it
determines whether to boot directly to the kernel or to the bootloader.
CONTAINER-SHARED-NETWORK? determines if the container will use a separate
network namespace.
When DERIVATIONS-ONLY? is true, print the derivation file name(s) without
building anything.
@ -883,6 +891,7 @@ static checks."
#:file-system-type file-system-type
#:image-size image-size
#:full-boot? full-boot?
#:container-shared-network? container-shared-network?
#:mappings mappings))
;; For 'init' and 'reconfigure', always build BOOTCFG, even if
@ -1020,6 +1029,8 @@ Some ACTIONS support additional ARGS.\n"))
(display (G_ "
--share=SPEC for 'vm', share host file system according to SPEC"))
(display (G_ "
-N, --network for 'container', allow containers to access the network"))
(display (G_ "
-r, --root=FILE for 'vm', 'vm-image', 'disk-image', 'container',
and 'build', make FILE a symlink to the result, and
register it as a garbage collector root"))
@ -1066,6 +1077,9 @@ Some ACTIONS support additional ARGS.\n"))
(lambda (opt name arg result)
(alist-cons 'image-size (size->number arg)
result)))
(option '(#\N "network") #f #f
(lambda (opt name arg result)
(alist-cons 'container-shared-network? #t result)))
(option '("no-bootloader" "no-grub") #f #f
(lambda (opt name arg result)
(alist-cons 'install-bootloader? #f result)))
@ -1182,6 +1196,8 @@ resulting from command-line parsing."
#:file-system-type (assoc-ref opts 'file-system-type)
#:image-size (assoc-ref opts 'image-size)
#:full-boot? (assoc-ref opts 'full-boot?)
#:container-shared-network?
(assoc-ref opts 'container-shared-network?)
#:mappings (filter-map (match-lambda
(('file-system-mapping . m)
m)