From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: [PATCH] services: lsh: Add "graceful" handling of daemonic option.
Date: Sat, 06 Dec 2014 15:28:34 +0100
Message-ID: <87k324zwbx.fsf@gnu.org>
References: <CAJ41eewmqwPhQXZRJXdJuHGA=sSRJG7dK86sWfCgusb+AXBNxg@mail.gmail.com>
	<CAJ41eewv6GMBtoaTCiHmifiOMKsy6UkVripMxDjQAAFnh2qJgg@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Return-path: <guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:55789)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <ludo@gnu.org>) id 1XxGLl-0007ru-Hb
	for guix-devel@gnu.org; Sat, 06 Dec 2014 09:28:54 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <ludo@gnu.org>) id 1XxGLc-00051u-GY
	for guix-devel@gnu.org; Sat, 06 Dec 2014 09:28:45 -0500
Received: from hera.aquilenet.fr ([2a01:474::1]:49736)
	by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from <ludo@gnu.org>)
	id 1XxGLc-00051q-9C
	for guix-devel@gnu.org; Sat, 06 Dec 2014 09:28:36 -0500
In-Reply-To: <CAJ41eewv6GMBtoaTCiHmifiOMKsy6UkVripMxDjQAAFnh2qJgg@mail.gmail.com>
	(Deck Pickard's message of "Thu, 4 Dec 2014 23:24:02 +0100")
List-Id: "Development of GNU Guix and the GNU System distribution."
	<guix-devel.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/guix-devel>
List-Post: <mailto:guix-devel@gnu.org>
List-Help: <mailto:guix-devel-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=subscribe>
Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org
Sender: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org
To: Deck Pickard <deck.r.pickard@gmail.com>
Cc: guix-devel@gnu.org

Deck Pickard <deck.r.pickard@gmail.com> skribis:

> From 1fef935d6292016c04b9234eedb5dcaf006dc152 Mon Sep 17 00:00:00 2001
> From: nebuli <nebu@kipple>
> Date: Wed, 3 Dec 2014 22:51:48 +0100
> Subject: [PATCH] services: lsh: Add graceful handling of daemonic option.
>
> * doc/guix.texi: Mention use case.
> * gnu/services/ssh.scm (lsh-service): New #:keys (daemonic?, pid-file?,
>   pid-file).  Build new lshd-command and expand service-requirement
>   field.

Nice!

>  (define* (lsh-service #:key
>                        (lsh lsh)
> +                      (daemonic? #f)
>                        (host-key "/etc/lsh/host-key")
>                        (interfaces '())
>                        (port-number 22)
>                        (allow-empty-passwords? #f)
>                        (root-login? #f)
>                        (syslog-output? #t)
> +                      (pid-file? #f)
> +                      (pid-file "/var/run/lshd.pid")
>                        (x11-forwarding? #t)
>                        (tcp/ip-forwarding? #t)
>                        (password-authentication? #t)

I would be tempted to not expose #:daemonic?, #:pid-file? and
#:syslog-output?, and instead always use --daemonic --pid-file=3D...

In particular, when using --daemonic, having the PID file is required,
otherwise dmd won=E2=80=99t know what the PID of this process is, and thus =
will
be unable to control it.  For that reason, #:pid-file? must not be
exposed.

WDYT?

> +  (define requires
> +    (if (and daemonic? syslog-output?)
> +        '(networking syslogd)
> +        '(networking)))

If we agree on the above, that would become '(networking syslogd)
unconditionally.

>      (return (service
>               (documentation "GNU lsh SSH server")
>               (provision '(ssh-daemon))
> -             (requirement '(networking))
> +             (requirement #~(#$@requires))

This is strictly equivalent to:

  (requirement `(,@requires))

or simply:

  (requirement requires)

:-)

G-expressions are only needed when capturing references to /gnu/store
items, packages, etc.

Thanks,
Ludo=E2=80=99.