Subject: [bug#58017] bug#57978: [PATCH 2/2] substitute: Retry downloading when a nar is unavailable.

From: zimoun <[email-masked]>
Date: Fri, 23 Sep 2022 10:17:16 +0200

Hi,

On ven., 23 sept. 2022 at 08:19, Ludovic Courtès <[email-masked]> wrote:

> Fixes <https://issues.guix.gnu.org/57978>
> Reported by Attila Lendvai <[email-masked]>.
>
> Previously, if a narinfo was available but its corresponding nar was
> missing (for instance because the narinfo was cached and the server
> became unreachable in the meantime), 'guix substitute --substitute'
> would try to download the nar from its preferred location and abort when
> that fails.  This change forces one retry with each of the URLs.
>
> * guix/scripts/substitute.scm (download-nar): Do not catch
> 'http-get-error?' exceptions.
> (system-error?, network-error?, process-substitution/fallback): New
> procedures.
> (process-substitution): Call 'process-substitution/fallback' upon
> 'network-error?'.
> * tests/substitute.scm ("substitute, first URL has narinfo but lacks nar, second URL unauthorized")
> ("substitute, first URL has narinfo but nar is 404, both URLs authorized")
> ("substitute, first URL has narinfo but nar is 404, one URL authorized")
> ("substitute, narinfo is available but nar is missing"): New tests.

LGTM.

> +(test-equal "substitute, first URL has narinfo but nar is 404, one URL authorized"
> +  "Substitutable data."
> +  (with-narinfo*
> +      (string-append %narinfo "Signature: "
> +                     (signature-field
> +                      %narinfo
> +                      #:public-key %wrong-public-key))
> +      %main-substitute-directory
> +
> +    (with-http-server `((200 ,(string-append %narinfo "Signature: "
> +                                             (signature-field
> +                                              %narinfo
> +                                              #:public-key %wrong-public-key)))
> +                        (404 "Sorry, nar is missing!"))
> +      (let ((url1 (%local-url)))
> +        (parameterize ((%http-server-port 0))
> +          (with-http-server `((200 ,(string-append %narinfo "Signature: "
> +                                                   (signature-field %narinfo)))
> +                              (404 "Sorry, nar is missing!"))
> +            (let ((url2 (%local-url)))
> +              (dynamic-wind
> +                (const #t)
> +                (lambda ()
> +                  (parameterize ((substitute-urls
> +                                  (list url1 url2
> +                                        (string-append "file://"
> +                                                       %main-substitute-directory))))
> +                    (request-substitution (string-append (%store-prefix)
> +                                                         "/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
> +                                          "substitute-retrieved"))
> +                  (call-with-input-file "substitute-retrieved" get-string-all))
> +                (lambda ()
> +                  (false-if-exception (delete-file "substitute-retrieved")))))))))))

Although I do not understand this test.  Why is 404 appearing twice?

Cheers,
simon