bug#58895: GNU ELPA: Stale badges in GitHub cache

bug#58895: GNU ELPA: Stale badges in GitHub cache

[Stefan Kangas]

Severity: minor

I often see stale badges in the GitHub cache, sometimes for several
days.  I think we should use a "Cache-Control" header when serving them:

    $ curl -i https://elpa.gnu.org/packages/url-scgi.svg
    HTTP/1.1 200 OK
    Date: Sun, 30 Oct 2022 14:45:24 GMT
    Server: Apache/2.4.54 (Debian)
    Last-Modified: Sat, 29 Oct 2022 21:04:31 GMT
    ETag: "4c2-5ec32b879e704"
    Accept-Ranges: bytes
    Content-Length: 1218
    Content-Type: image/svg+xml
    [...]

Here, we should also have:

    Cache-Control: max-age=21600, must-revalidate

This should ensure that they are only ever cached for 12 hours, which
roughly coincides with how often we update the archive.

Probably something like this in .htaccess should suffice:

    <FilesMatch ".+\.svg$">
        Header unset Cache-Control
        Header set Cache-Control "max-age=21600, must-revalidate"
    </FilesMatch>

For more, see:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
https://httpd.apache.org/docs/2.4/mod/core.html#filesmatch

bug#58895: GNU ELPA: Stale badges in GitHub cache

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

> I often see stale badges in the GitHub cache, sometimes for several
> days.  I think we should use a "Cache-Control" header when serving them:

Hmm... we had a directive for that in Apache's config, but it wasn't
quite right.  It should be working now.
It uses slightly different settings.
You said "12 hours", your code sais 6 hours, and the code we had used
24 hours.  I kept the 24 hours.

Your code said "must-revalidate", the code we had (and still have)
said/says "public".  I think public is right, but I don't really know
what "must-revalidate" (or its lack) implies.


        Stefan

bug#58895: GNU ELPA: Stale badges in GitHub cache

[Stefan Kangas]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> Hmm... we had a directive for that in Apache's config, but it wasn't
> quite right.  It should be working now.
> It uses slightly different settings.
> You said "12 hours", your code sais 6 hours, and the code we had used
> 24 hours.  I kept the 24 hours.

Sounds good, thanks.

> Your code said "must-revalidate", the code we had (and still have)
> said/says "public".  I think public is right, but I don't really know
> what "must-revalidate" (or its lack) implies.

From reading the docs, "public" should be fine.