Subject: bug#55820: closed (Re: bug#63634: nar 404 leads to hard‘guix substitute’ crash)

From: [email-masked] (GNU bug Tracking System)
Date: Mon, 22 May 2023 15:18:02 +0000

Your bug report

#55820: Substitute server errors lead to client crashes

which was filed against the guix package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
55820: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=55820
GNU Bug Tracking System
Contact [email-masked] with problems

Subject: Re: bug#63634: nar 404 leads to hard ‘guix substitute’ crash
From: Ludovic Courtès <[email-masked]>
To: [email-masked], [email-masked]
Date: Mon, 22 May 2023 17:16:53 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi,

Ludovic Courtès <[email-masked]> skribis:

>     646:2 10 (process-substitution _ _ _ #:cache-urls _ #:acl _ # _ # …)
> In ice-9/boot-9.scm:
>   1752:10  9 (with-exception-handler _ _ #:unwind? _ # _)
> In guix/scripts/substitute.scm:
>     463:7  8 (download-nar #<<narinfo> path: "/gnu/store/dg0rm1mp9q…> …)
> In ice-9/boot-9.scm:
>   1747:15  7 (with-exception-handler #<procedure 7f6df0fa71e0 at ic…> …)
>   1685:16  6 (raise-exception _ #:continuable? _)
>   1683:16  5 (raise-exception _ #:continuable? _)
>   1685:16  4 (raise-exception _ #:continuable? _)
>   1780:13  3 (_ #<&compound-exception components: (#<&error> #<&irri…>)
>   1685:16  2 (raise-exception _ #:continuable? _)
>   1683:16  1 (raise-exception _ #:continuable? _)
>   1685:16  0 (raise-exception _ #:continuable? _)
>
> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> ERROR:
>   1. &http-get-error:
>       uri: #<<uri> scheme: https userinfo: #f host: "bordeaux.guix.gnu.org" port: #f path: "/nar/zstd/dg0rm1mp9qvjhvlwra5mc8dz5pfky4hj-guile-colorized-0.1" query: #f fragment: #f>
>       code: 404
>       reason: "Not Found"
>       headers: ((server . "nginx") (date . #<date nanosecond: 0 second: 39 minute: 59 hour: 21 day: 21 month: 5 year: 2023 zone-offset: 0>) (content-type text/plain (charset . "utf-8")) (content-length . 3) (connection keep-alive))
>   2. &message: "https://bordeaux.guix.gnu.org/nar/zstd/dg0rm1mp9qvjhvlwra5mc8dz5pfky4hj-guile-colorized-0.1: HTTP download failed: 404 (\"Not Found\")"
> substitution of /gnu/store/dg0rm1mp9qvjhvlwra5mc8dz5pfky4hj-guile-colorized-0.1 failed

[...]

> This might be related to 8bd4126917f59f4af9a4323c3d5699201862dca2.  The
> two ‘download-nar’ calls are guarded against ‘http-get-error?’ though.

That the exception went through despite the ‘network-error?’ guard is
fixed by 3f59fd6d114548480c719d4b8f8509bdf3e8dcca.

The reason was that the ‘&http-get-error’ condition was getting wrapped
in a ‘kind-and-args’ exception upon rethrow, as illustrated here:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> (catch #t
		       (lambda () (raise-exception (condition (&message (message "boo")))))
		       (lambda args args))
$5 = (%exception #<&message message: "boo">)
scheme@(guile-user)> (with-exception-handler (lambda (e) e)
		       (lambda () (apply throw $5))
		       #:unwind? #t)
$6 = #<&compound-exception components: (#<&error> #<&irritants irritants: (#<&message message: "boo">)> #<&exception-with-kind-and-args kind: %exception args: (#<&message message: "boo">)>)>
scheme@(guile-user)> (message-condition? $6)
$7 = #f
--8<---------------cut here---------------end--------------->8---

Ludo’.

Subject: Substitute server errors lead to client crashes
From: Ludovic Courtès <[email-masked]>
To: [email-masked]
Date: Mon, 06 Jun 2022 14:48:22 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Here’s an example of a substitute server issue that leads to ugly client
crashes:

--8<---------------cut here---------------start------------->8---
$ guix upgrade

[…]

guix substitute: warning: while fetching https://bordeaux.guix.gnu.org/nar/lzip/fan4wanq1138ds9pj0s63f2iv4qygng0-dstat-0.7.4: server is somewhat slow
guix substitute: warning: try `--no-substitutes' if the problem persists
Backtrace:
In ice-9/boot-9.scm:
  1752:10 19 (with-exception-handler _ _ #:unwind? _ # _)
In unknown file:
          18 (apply-smob/0 #<thunk 7f0e562b2f60>)
In ice-9/boot-9.scm:
    724:2 17 (call-with-prompt _ _ #<procedure default-prompt-handleâ¦>)
In ice-9/eval.scm:
    619:8 16 (_ #(#(#<directory (guile-user) 7f0e562acc80>)))
In guix/ui.scm:
   2206:7 15 (run-guix . _)
  2169:10 14 (run-guix-command _ . _)
In ice-9/boot-9.scm:
  1752:10 13 (with-exception-handler _ _ #:unwind? _ # _)
  1752:10 12 (with-exception-handler _ _ #:unwind? _ # _)
In guix/scripts/substitute.scm:
   771:15 11 (_)
In ice-9/exceptions.scm:
   406:15 10 (process-substitution #<output: file 4> _ "/gnu/store/â¦" â¦)
In ice-9/boot-9.scm:
  1752:10  9 (with-exception-handler _ _ #:unwind? _ # _)
In guix/scripts/substitute.scm:
    479:9  8 (_)
In ice-9/boot-9.scm:
  1747:15  7 (with-exception-handler #<procedure 7f0e53925f00 at icâ¦> â¦)
  1685:16  6 (raise-exception _ #:continuable? _)
  1683:16  5 (raise-exception _ #:continuable? _)
  1685:16  4 (raise-exception _ #:continuable? _)
  1780:13  3 (_ #<&compound-exception components: (#<&error> #<&irriâ¦>)
  1685:16  2 (raise-exception _ #:continuable? _)
  1683:16  1 (raise-exception _ #:continuable? _)
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
ERROR:
  1. &http-get-error:
      uri: #<<uri> scheme: https userinfo: #f host: "bordeaux.guix.gnu.org" port: #f path: "/nar/lzip/fan4wanq1138ds9pj0s63f2iv4qygng0-dstat-0.7.4" query: #f fragment: #f>
      code: 502
      reason: "Bad Gateway"
  2. &message: "https://bordeaux.guix.gnu.org/nar/lzip/fan4wanq1138ds9pj0s63f2iv4qygng0-dstat-0.7.4: HTTP download failed: 502 (\"Bad Gateway\")"
substitution of /gnu/store/fan4wanq1138ds9pj0s63f2iv4qygng0-dstat-0.7.4 failed
guix upgrade: error: corrupt input while restoring archive from socket
--8<---------------cut here---------------end--------------->8---

This should be handled gracefully.

Also, in this case, ‘--fallback’ appears to have no effect.

Ludo’.