bug#26035: guix pull does not handle url lists and unreachable requests

[ng0 <contact.ng0@cryptolab.net>]

ng0 transcribed 1.6K bytes:
> efficient enough and sets the times out much too high

Curses, my mailing program broke the subject. I thought I fixed it.

> Reply-To: 
> In-Reply-To:
> When you configure a system to use bayfront, for example with these
> lines included in cons* of (services):
>             (modify-services
>               %base-services
>               (guix-service-type
>                 config =>
>                 (guix-configuration
>                   (inherit config)
>                   (substitute-urls
>                     (cons* "https://bayfront.guixsd.org"
>                            %default-substitute-urls))
>                   (authorized-keys
>                     (cons*
>                       (plain-file "bayfront.guixsd.org.pub"
>                         (string-append "(public-key (ecc curve
> Ed25519) "
>                                        "(q
> #8D156F295D24B0D9A86FA5741A840FF2"
> 
> "D24F60F7B6C4134814AD55625971B394#)))"))
>                     %default-authorized-guix-keys))))))))
> 
> please consider that this does not reflect the actual indent and that I
> can't paste all of the config here, but those are the relevant parts,
> you will experience that: "guix package", and "guix system" (or guix
> buld?) query all listed subsitute urls, while "guix pull" only queries
> the first one. If the first one is experiencing issues (for example
> server is offline or can't handle requests for whatever reasons), the
> timeout is much too high. I had to cancel guix pull processes which
> tried to request from bayfront.guixsd.org for 9, 12, and 3 hours.
> 
> As bayfront wasn't the only server, a switch should occur even with the
> guix pull part where substitute servers are queried before the build of
> the fetched master tarball starts.
> 
> 
>