Description

There is currently a new RFC published for cache-control headers specific for CDN's. It was created by 3 authors working at cloudflare, akamai and fastly.

https://datatracker.ietf.org/doc/rfc9213/

I think it would be great if the HttpFoundation make it easier to control this headers so we have the same functionality like we have now for the Cache-Control header in the Response Class.

Some more links beside the rfc above:

• https://blog.cloudflare.com/cdn-cache-control/
• https://developers.cloudflare.com/cache/about/cdn-cache-control/
• https://www.akamai.com/blog/news/targeted-cache-control
• Twitter Discussion Fastly: https://twitter.com/crucially/status/1557804735419355137

Example

I think the following methods of the HeaderBag would be effect by an "optional" targeted header variable (CDN-Cache-Control, Fastly-Cache-Control, Cloudflare-Cache-Control):

• addCacheControlDirective
• removeCacheControlDirective
• getCacheControlDirective
• hasCacheControlDirective

The following method on the Response would also be effected by "optional" header name:

• setMaxAge
• setStaleIfError
• setStaleWhileRevalidate
• setCache
• setPrivate
• setPublic
• isCacheable
• setImmutable?

Why at first way it looks like it make sense the following I think have no effect on -cache-control header:

• setSharedMaxAge (cas aching is set via setMaxAge)

Also the Symfony Cache itself should keep the "-Cache-Control" header in mind. In general it is mostly a CDN-Cache-Control and an own name in case of Symfony it would make sense to call it Symfony-Cache-Control.

This headers make it clearer if the response itself is cachable by a server side cache but maybe not by a client side cache (including private ESI's) currently this kind of controlling was not very transparent and FOSHttpCache did workaround by a custom X-Reverse-Proxy-TTL which did not support other things like stale-if-error, statle-while-revalidate, ... Original discussion started there some time ago before the RFC was available: FriendsOfSymfony/FOSHttpCache#455.

PS: As seen above the RFC goes with <Targeted>-Cache-Control while it maybe would first make sense to give only <targeted> into the methods above. It would be better go give the whole header name into it like CDN-Cache-Control this make it possible to support none standardized headers like Surrogate-Control (fastly) and Edge-Control (akamai) also.

Mention some cache related persons: @dbu, @andrerom, @Toflar