Support ui.run(cache_control_directives=)

[evnchn]

#4532 (comment)

TL-DR:

• Cache the static assets more aggressively, but we don't know how much is enough, and afraid overdo it.
• Expose cache_control_directives argument in ui.run and ui.run_with, with default being long 1-year cache*
• Better than original solution because:
  • Centralized management, as @falkoschindler pointed out
  • Ability to set other directives such as immutable (not available for Chrome), stale-while-revalidate (available for Chrome)

Concerns:

• Is ui.run and ui.run_with the best place to add the parameter?
• *Should we set the default to "public, max-age=3600" to match the default behaviour from before the PR (maximize compatibility), or let the better (?) 1-year-cache be the default (maximize rollout of performance increase)?

Testing:

ui.run()

ui.run(cache_control_directives='no-store')

[falkoschindler]

Thanks, @evnchn!
I moved the new parameter a few lines up to group it with other durations like the reconnect timeout.
Apart from that I have two open questions:

• The docstrings say "cache control directives for static files". But methods like app.add_static_files have a separate max cache age which still defaults to an hour. Therefore I'm searching for a better description.
• The middleware matches paths starting with "/nicegui/...". But I'm not 100% sure if this works in combination with a path prefix, like in https://github.com/zauberzeug/nicegui/tree/main/examples/nginx_subpath.

Last but not least, I think we should block this PR until PR #4539 ("Cachebusting") is merged. Changing the cache to one year without handling custom components would cause quite some trouble.

[evnchn]

1. Sorry for that oversight. Should be "cache control directives for NiceGUI internal files"
2. According to the config, a request made to http://nginx.server/nicegui/hello would be relayed to http://localhost:8080/hello.

        location ~ ^/nicegui/(.*)$ {
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection $connection_upgrade;
            proxy_set_header Authorization $http_authorization;
            proxy_pass_header Authorization;

            proxy_pass http://app:8080/$1?$args;
            proxy_set_header X-Forwarded-Prefix /nicegui;
            proxy_redirect http://app:8080/ /nicegui/;

• It is mentioned that the entire app is available below "/nicegui" but the code does not need to know that., so the only way the line if request.url.path.startswith(f'/_nicegui/{__version__}/'): fails, is if it parses X-Forwarded-Prefix and mutates the path, which would be a security vulnerability (what's to stop me sending such header directly to a bare NiceGUI server, cough cough Next.js 🤡), and just doesn't make any sense.

[evnchn]

Final note: If you want to add this PR before cachebusting PR is merged, then set the default parameter of cache_control_directives to be exactly what would be served before this PR (public, max-age=3600)

But I persoanlly don't recommend rushing it. Seems a bad look if we add a parameter only that the default value changes from one version to another in a minor release.