linux-container: Support container network sharing.

* 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>

1 files changed, 18 insertions, 2 deletions

diff --git a/guix/scripts/system.scm b/guix/scripts/system.scm
index 3c3d6cbd5f..cf4418f981 100644
--- a/guix/scripts/system.scm
+++ b/guix/scripts/system.scm
@@ -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)