[bug#35697] [PATCH 4/8] linux-container: Do not add %CONTAINER-FILE-SYSTEMS to Docker image OSes.

[Ludovic Courtès]

Previously, 'guix system docker-image' would end up providing an OS that
would try to mount all of %CONTAINER-FILE-SYSTEMS as well as /gnu/store,
which is bound to fail in unprivileged Docker.

This patch makes it so that 'guix system container' still gets those
file systems, but 'guix system docker-image' doesn't.

* gnu/system/linux-container.scm (containerized-operating-system): Add
 #:extra-file-systems parameter and honor it.  Do not import
 %STORE-MAPPING.
(container-script): Add %STORE-MAPPING to MAPPINGS and pass
 #:extra-file-systems.
---
 gnu/system/linux-container.scm | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/gnu/system/linux-container.scm b/gnu/system/linux-container.scm
index ded5f279fe..5adec064f7 100644
--- a/gnu/system/linux-container.scm
+++ b/gnu/system/linux-container.scm
@@ -53,10 +53,12 @@ from OS that are needed on the bare metal and not in a 
container."
                      (return `(("locale" ,locale))))))
         base))
 
-(define (containerized-operating-system os mappings)
+(define* (containerized-operating-system os mappings
+                                         #:key
+                                         (extra-file-systems '()))
   "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."
+containerized OS.  EXTRA-FILE-SYSTEMS is a list of file systems to add to OS."
   (define user-file-systems
     (remove (lambda (fs)
               (let ((target (file-system-mount-point fs))
@@ -88,15 +90,17 @@ containerized OS."
                         (memq (service-kind service)
                               useless-services))
                       (operating-system-user-services os)))
-    (file-systems (append (map mapping->fs (cons %store-mapping mappings))
-                          %container-file-systems
+    (file-systems (append (map mapping->fs mappings)
+                          extra-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))
+  (let* ((os           (containerized-operating-system
+                        os (cons %store-mapping mappings)
+                        #:extra-file-systems %container-file-systems))
          (file-systems (filter file-system-needed-for-boot?
                                (operating-system-file-systems os)))
          (specs        (map file-system->spec file-systems)))
-- 
2.21.0