From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ludovic =?UTF-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Subject: bug#36731: shepherd lost track of nginx
Date: Mon, 22 Jul 2019 12:31:06 +0200
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References: <E22C505B-4E64-4489-AE9C-8B19254B2BBD@vllmrt.net>
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In-Reply-To: <871rykcniu.fsf@netris.org> (Mark H. Weaver's message of "Sat, 20
 Jul 2019 19:07:58 -0400")
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To: Mark H Weaver <mhw@netris.org>
Cc: 36731@debbugs.gnu.org, Robert Vollmert <rob@vllmrt.net>

Hi Mark,

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

> Ludovic Court=C3=A8s <ludo@gnu.org> writes:
>
>> Robert Vollmert <rob@vllmrt.net> skribis:
>>
>>> The result was this:
>>>
>>> $ sudo herd restart nginx
>>> Service nginx is not running.
>>> herd: exception caught while executing 'start' on service 'nginx':
>>> Throw to key `srfi-34' with args `("#<condition &invoke-error
>>> [program:
>>> \"/gnu/store/mlg0xfbiq03s812rm3v7mrlhyngas4xp-nginx-1.17.1/sbin/nginx\"
>>> arguments: (\"-c\"
>>> \"/gnu/store/r6gl9n7pwf4npiri05qxr40vdihdm2yy-nginx.conf\" \"-p\"
>>> \"/var/run/nginx\") exit-status: 1 term-signal: #f stop-signal: #f]
>>> 147e000>")=E2=80=99.
>
> [=E2=80=A6]
>
>>> That error message could also be clearer about what=E2=80=99s going on.=
 At any
>>> rate, after I killed the nginx process, =E2=80=9Cherd start nginx=E2=80=
=9D worked fine.
>>
>> I agree that we could and should improve the error message.
>
> On the subject of this error message, why was the &invoke-error
> condition serialized to a string before apparently being embedded within
> another exception?

That serialization comes from the Shepherd when it talks to its clients
(see =E2=80=98write-reply=E2=80=99 in (shepherd comm)).

Normally service methods should write a human-readable message instead
of throwing an exception, but when that happens, shepherd serializes
those things so that one can at least diagnose the problem.

In this case we could use =E2=80=98report-invoke-error=E2=80=99 from (guix =
build utils)
on =E2=80=98core-updates=E2=80=99.

Thanks,
Ludo=E2=80=99.