Re: Error handling when 'guix substitute' dies

[Ada Stevenson]

Hi Ludo',

On 3/24/24 11:15 AM, Ludovic Courtès wrote:
> Hi Ada,
>
> Ada Stevenson <adanskana@gmail.com> skribis:
>
> > Sometimes, usually when I'm on an enterprise network like my
> > university's of library's wifi, the `guix substitute` process dies
> > with a "TLS error in procedure 'write_to_session_record_port': Error
> > in the push function" error message. My connection is rock-solid
> > otherwise, and sometimes it doesn't happen at all.
> What version of guix-daemon are you using?  Was it installed through
> ‘guix pull’ or via another distro?
>
> I’ve seen this before but I haven’t experienced it in a long time, so I
> wonder if I’m just lucky or if there are other factors at play.
I'm running the up-to-date daemon, 1.4.0-18.4c94b9e, on Guix System.
> > I'm not sure if this is a fault in the actual Guix code, or there's
> > some Guile library somewhere that has this bug. Anyway, I think it
> > would be a useful feature to have a way to automatically restart the
> > `guix substitute` process or otherwise recover from this error. Some
> > sort of `--restart=no.restarts.permitted` flag. Whenever I'm updating
> > my system I tend to leave and do something else, and when this happens
> > I come back and nothing's actually been done, and the error is
> > transient so I don't gain anything from seeing this message.
> ‘guix substitute’ is a ‘guix-daemon’ helper, which automatically
> (re)starts it when needed.
>
> Now, what we could do is have ‘guix substitute’ gracefully handle those
> errors and keep going.  I believe this one-liner should do it:
>
>
> diff --git a/guix/scripts/substitute.scm b/guix/scripts/substitute.scm
> index 37cd08e289..3af0bf0019 100755
> --- a/guix/scripts/substitute.scm
> +++ b/guix/scripts/substitute.scm
> @@ -494,7 +494,9 @@ (define* (download-nar narinfo destination
>     (define (try-fetch choices)
>       (match choices
>         (((uri compression file-size) rest ...)
> -       (guard (c ((and (pair? rest) (http-get-error? c))
> +       (guard (c ((and (pair? rest)
> +                       (or (http-get-error? c)
> +                           (network-error? c)))
>                     (warning (G_ "download from '~a' failed, trying next URL~%")
>                              (uri->string uri))
>                     (try-fetch rest)))
>
> I’ll go ahead with this change if there are no objections.
Looks good to me! Thanks for looking into this :)
> Thanks,
> Ludo’.

Thanks,

Ada