Customizing /etc

[Ludovic Courtès]

Alex Kost <address@hidden> skribis:

> Ludovic Courtès (2016-09-14 16:58 +0200) wrote:
>
>> Hello,
>>
>> address@hidden (Carlos Sánchez de La Lama) skribis:
>>
>>> I have an interesting case here. I have guile installed in my system
>>> profile, so that
>>>
>>> /var/guix/profiles/system/profile/share/aclocal/guile.m4
>>>
>>> is there. However, autoconf is installed in my *user* profile, so
>>> ACLOCAL_PATH is augmented in ~/.guix-profile/etc/profile to include
>>>
>>> ~/.guix-profile/share/aclocal
>>>
>>> But not the system-profile aclocal directory, which would be put into
>>> ACLOCAL_PATH by /var/guix/profiles/system/profile/etc/profile if
>>> autoconf was installed in the systme profile as well.
>>>
>>> Is this the intended behaviour? I am wondering whether packages with
>>> search paths should include both the user-profile directories and the
>>> system-profile ones.
>>
>> I think you’re right.  This was discussed at
>> <http://bugs.gnu.org/20255>, leading to a patch (for GuixSD).
>>
>> However, we failed to build consensus around the approach of this patch,
>> so we did not apply it.  If you have ideas, please email
>> address@hidden  :-)
>
> I think I was the one who prevents the consensus.  To make it clear, I'm
> for the suggested solution, but only *after* giving a user a freedom to
> avoid loading such a heavy command as "guix package --search-paths".  On
> a "usual" GNU/Linux distro a user can edit /etc/profile, but on GuixSD
> it is not possible currently.  That's why I think there should be
> provided a possibility to override /etc/profile at first.

Indeed, thanks for the reminder!

In fact, we have this through ‘etc-service-type’, except that currently
/etc/profile is systematically added.

So an idea that comes to mind is to allow ‘etc-service-type’ to be
extended with procedures that would be able to filter or otherwise
change the /etc entries (similar to what we do for PAM):

diff --git a/gnu/services.scm b/gnu/services.scm
index 7e322c5..9397232 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -426,9 +426,13 @@ directory."
                 (extensions
                  (list
                   (service-extension activation-service-type
-                                     (lambda (files)
-                                       (let ((etc
-                                              (files->etc-directory files)))
+                                     (lambda (files+procs)
+                                       (let* ((proc (apply compose
+                                                           (filter procedure?
+                                                                   
files+procs)))
+                                              (files (filter pair? 
files+procs))
+                                              (etc
+                                               (files->etc-directory (proc 
files))))
                                          #~(activate-etc #$etc))))
                   (service-extension system-service-type etc-entry)))
                 (compose concatenate)

In your config, you could have something like:

  (services (cons (simple-service 'rm-/etc/profile etc-service-type
                                  (const (lambda (files)
                                           (assoc-delete "profile" files))))
                  %base-services))

WDYT?

In fact I think we would need to have a more generic mechanism to hook
into ‘fold-services’, but I’m not sure what it should look like.

Ludo’.