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Subject: [bug#30498] [WIP v2 shepherd] shepherd: If /dev/kmsg is writable,
	use it for logging.
Resent-Message-ID: <handler.30498.B30498.151966828827318@debbugs.gnu.org>
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
References: <20180217122035.1443-1-dannym@scratchpost.org>
	<20180217164835.1178-1-dannym@scratchpost.org>
Date: Mon, 26 Feb 2018 19:04:44 +0100
In-Reply-To: <20180217164835.1178-1-dannym@scratchpost.org> (Danny
	Milosavljevic's message of "Sat, 17 Feb 2018 17:48:35 +0100")
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To: Danny Milosavljevic <dannym@scratchpost.org>
Cc: 30498@debbugs.gnu.org

Hi!

Danny Milosavljevic <dannym@scratchpost.org> skribis:

> * modules/shepherd.scm (main): If /dev/kmsg is used, don't log to console
> again - use only /dev/kmsg.  Also redirect stderr to /dev/kmsg in
> that case.
> * modules/shepherd/comm.scm (%current-logfile-date-format): New variable.
> (make-shepherd-output-port): Use it.  Export.
> * modules/shepherd/support.scm (default-logfile-date-format): New variabl=
e.
> (default-logfile): Use /dev/kmsg if writable.
> (default-logfile-date-format): Drop duplicate timestamp.

[...]

> --- a/modules/shepherd.scm
> +++ b/modules/shepherd.scm
> @@ -141,12 +141,20 @@
>      ;; Enable logging as first action.
>      (start-logging logfile)
>=20=20
> +    (if (string=3D? logfile "/dev/kmsg")
> +        ;; Prevent duplicate messages.
> +        (set-current-output-port (%make-void-port "w")))

Nitpick: I=E2=80=99d use =E2=80=98when=E2=80=99 here since there=E2=80=99s =
no =E2=80=98else=E2=80=99 branch.

> +(define %current-logfile-date-format
> +  (make-parameter default-logfile-date-format))

Please add a one-line comment explaining what the format is.

Could you also add a couple of lines in the .texi file explaining that
/dev/kmsg is used when it=E2=80=99s available and we=E2=80=99re running as =
root?

As for cryptsetup, what if the service that runs crypsetup simply
parameterizes =E2=80=98log-output-port=E2=80=99 to /dev/console?  That woul=
d give us the
current behavior, right?

Apart from that it LGTM, thank you!

Ludo=E2=80=99.