fix(admin): Add a note about JavaScript modules to Nextcloud 28 upgrade guides

[susnux]

☑️ Resolves

• Fix Add mjs to upgrade guide for admins #11429

🖼️ Screenshots

[susnux]

/backport to stable28

[MichaIng]

At least on Debian, the MIME type is added automatically for all webservers, with their own configs or /etc/mime.types, so this part is probably less important. However, in which case and which absolute directory are you expecting conf/mime.types? Like this, me, and hence I guess many others, won't be able to know what to do, if the correct MIME type is really not served anyway. Not sure whether /etc/mime.types is used across all (relevant) distros and webservers, but this is probably a more clear config to look at? For Apache otherwise /etc/apache2/mods-available/mime.conf, or of course any other server/vhost config.

Just checked back: Nginx uses /etc/nginx/mime.types, Apache and Lighttpd use /etc/mime.types.

What I was actually missing in the docs was not the MIME type (still good to mention it), but the rewrites: The default/example webserver configs rewrite everything to index.php, which is not explicitly excluded from the rewrite, via RewriteCond in Apache, and location ~ \.(?:...|mjs|...) { block in Nginx.

Another thing is the Cache-Control header. So basically 3 things:

1. Assure that requests to .mjs are not rewritten to index.php but served directly.
2. Assure that .mjs files are served with text/javascript MIME type.
3. Serve .mjs files with Cache-Control "max-age=15778463" header, like other static assets, respectively Cache-Control "max-age=15778463, immutable" for those with v= query parameter.

All of this can be usually achieved by adding mjs to the list(s) of asset file extensions in the existing Nextcloud webserver config.

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[st3iny]

@MichaIng Nice summary. Do we need to do anything else here or is this PR sufficient?

[MichaIng]

@st3iny
None of the points I listed are addressed in this PR yet 😉. Let me do a concrete suggestion.

[MichaIng]

Suggested change

	* As some core app now make use of JavaScript modules, make sure your web server is serving ``.mjs`` files with JavaScript MIME type.
	When using Apache with ``.htaccess`` configuration this will be done automatically, if your Apache is not configured to use the ``.htaccess`` files make sure ``.mjs`` is added as a file extension for JavaScript in ``conf/mime.types``.
	For NGinx please refer to the our recommended :ref:`nginx configuration<nginx-config>`.
	* As some core app now make use of JavaScript modules, make sure your web server is not rewriting requests to ``.mjs`` files, but serves them with `text/javascript` MIME type and proper `Cache-Control` header, like ``.js`` and other static file extensions.
	* When using Apache with ``.htaccess`` configuration, this will be done automatically.
	* For Nginx, please refer to the our recommended :ref:`Nginx configuration<nginx-config>`.
	* For other setups, make sure to add ``.mjs`` to the list of static file extensions in web server configs and in case define its MIME type in `/etc/mime.types`.

• I hope nested lists work like that.
• The last point is moreless taken from the above point about .ogg and .flac files. Most web server configs have one or more blocks with a list of all static file extensions Nextcloud makes use of. Adding .mjs there to be handled like .js and others, should be sufficient in most cases. The MIME type might be the only exception on older distros, where default /etc/mime.types or related default web server configs do not contain .mjs yet.

[kesselb]

/backport to stable29

[kesselb]

I merged the pr to finally get it in.

@MichaIng would you mind shooting a follow-up with your suggestions?

[MichaIng]

@kesselb
Done: #11912