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From: Ludovic =?UTF-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Subject: bug#37207: guix.gnu.org Last Modified at epoch
Date: Thu, 26 Sep 2019 10:39:45 +0200
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In-Reply-To: <877e6xqrtw.fsf@nckx> (Tobias Geerinckx-Rice's message of "Wed,
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To: Tobias Geerinckx-Rice <me@tobias.gr>
Cc: 37207@debbugs.gnu.org

Hi Tobias,

Tobias Geerinckx-Rice <me@tobias.gr> skribis:

> Turning these off will of course prevent all caching.  I don't know if
> that would add measurable load to guix.gnu.org (it would be more
> problematic if we used a CDN, but it might still make a difference).
>
> Nix does something both interesting and icky =E2=80=94 as always: patch[0]
> nginx to look up the realpath() instead, so clients can still cache
> using If-None-Match.

> [0]: https://github.com/NixOS/nixpkgs/pull/48337

(See
<https://raw.githubusercontent.com/NixOS/nixpkgs/9bc23f31d29138f09db6af5270=
8a9b8b64deec64/pkgs/servers/http/nginx/nix-etag-1.15.4.patch>.)

I had overlooked this patch but it looks like the right approach
overall.  Calling =E2=80=98realpath=E2=80=99 each time seems a bit expensiv=
e as it
creates an =E2=80=98lstat=E2=80=99 storm, but I can=E2=80=99t think of a be=
tter solution.

I also found this post whose main interest is in showing how to write a
plugin to generate custom etags:

  https://mikewest.org/2008/11/generating-etags-for-static-content-using-ng=
inx/

Thoughts?

Ludo=E2=80=99.