GNU bug report logs - #26809
08/09: services: nscd: Create /etc/resolv.conf if it does not exist.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: bug-guix <at> gnu.org
Subject: Re: 08/09: services: nscd: Create /etc/resolv.conf if it does not
 exist.
Date: Sun, 07 May 2017 00:19:33 -0400

ludo <at> gnu.org (Ludovic Courtès) writes:

> civodul pushed a commit to branch master
> in repository guix.
>
> commit 49f9d7f697d19870f01104cdb6a90a32aea87679
> Author: Ludovic Courtès <ludo <at> gnu.org>
> Date:   Tue May 2 12:21:31 2017 +0200
>
>     services: nscd: Create /etc/resolv.conf if it does not exist.
>     
>     * gnu/services/base.scm (nscd-activation): Create /etc/resolv.conf if it
>     does not exist yet.

This commit broke the boot process on my system.  The problem is that
I'm using Network Manager, which makes /etc/resolv.conf into a symlink
that points to /var/run/NetworkManager/resolv.conf.  Since /var/run is
cleaned during early boot, when this new activation code runs,
/etc/resolv.conf is a broken symlink.

I guess that 'file-exists?' returns #false for a broken symlink, and the
'call-with-output-file' tries to open the target of the symlink, which
fails.

       Mark


> diff --git a/gnu/services/base.scm b/gnu/services/base.scm
> index 67972bf..a64faa0 100644
> --- a/gnu/services/base.scm
> +++ b/gnu/services/base.scm
> @@ -1149,7 +1149,14 @@ the tty to run, among other things."
>    #~(begin
>        (use-modules (guix build utils))
>        (mkdir-p "/var/run/nscd")
> -      (mkdir-p "/var/db/nscd")))                  ;for the persistent cache
> +      (mkdir-p "/var/db/nscd")                    ;for the persistent cache
> +
> +      ;; In libc 2.25 nscd uses inotify to watch /etc/resolv.conf, but only if
> +      ;; that file exists when it is started.  Thus create it here.
> +      (unless (file-exists? "/etc/resolv.conf")
> +        (call-with-output-file "/etc/resolv.conf"
> +          (lambda (port)
> +            (display "# This is a placeholder.\n" port))))))
>  
>  (define nscd-service-type
>    (service-type (name 'nscd)

Message #10 received at 26809-done <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: Mark H Weaver <mhw <at> netris.org>
Cc: 26809-done <at> debbugs.gnu.org
Subject: Re: bug#26809: 08/09: services: nscd: Create /etc/resolv.conf if it
 does not exist.
Date: Mon, 08 May 2017 16:30:06 +0200

Mark H Weaver <mhw <at> netris.org> skribis:

> ludo <at> gnu.org (Ludovic Courtès) writes:
>
>> civodul pushed a commit to branch master
>> in repository guix.
>>
>> commit 49f9d7f697d19870f01104cdb6a90a32aea87679
>> Author: Ludovic Courtès <ludo <at> gnu.org>
>> Date:   Tue May 2 12:21:31 2017 +0200
>>
>>     services: nscd: Create /etc/resolv.conf if it does not exist.
>>     
>>     * gnu/services/base.scm (nscd-activation): Create /etc/resolv.conf if it
>>     does not exist yet.
>
> This commit broke the boot process on my system.  The problem is that
> I'm using Network Manager, which makes /etc/resolv.conf into a symlink
> that points to /var/run/NetworkManager/resolv.conf.  Since /var/run is
> cleaned during early boot, when this new activation code runs,
> /etc/resolv.conf is a broken symlink.
>
> I guess that 'file-exists?' returns #false for a broken symlink, and the
> 'call-with-output-file' tries to open the target of the symlink, which
> fails.

Indeed.  I guess this is fixed by
c298fb133acbdc17e05a79c10ab9a9e214368264.

Thanks,
Ludo’.

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