Items tagged http, caching
Filters: http × caching × Sorted by date
Cloudflare does not consider vary values in caching decisions. Here’s the spot in Cloudflare’s documentation where they hide a crucially important detail:
“Cloudflare does not consider vary values in caching decisions. Nevertheless, vary values are respected when Vary for images is configured and when the vary header is vary: accept-encoding.”
This means you can’t deploy an application that uses content negotiation via the Accept header behind the Cloudflare CDN—for example serving JSON or HTML for the same URL depending on the incoming Accept header. If you do, Cloudflare may serve cached JSON to an HTML client or vice-versa.
There’s an exception for image files, which Cloudflare added support for in September 2021 (for Pro accounts only) in order to support formats such as WebP which may not have full support across all browsers. # 20th November 2023, 5:08 am
New HTTP standards for caching on the modern web (via) Cache-Status is a new HTTP header (RFC from August 2021) designed to provide better debugging information about which caches were involved in serving a request—“Cache-Status: Nginx; hit, Cloudflare; fwd=stale; fwd-status=304; collapsed; ttl=300” for example indicates that Nginx served a cache hit, then Cloudflare had a stale cached version so it revalidated from Nginx, got a 304 not modified, collapsed multiple requests (dogpile prevention) and plans to serve the new cached value for the next five minutes. Also described is $Target-Cache-Control: which allows different CDNs to respond to different headers and is already supported by Cloudflare and Akamai (Cloudflare-CDN-Cache-Control: and Akamai-Cache-Control:). # 21st October 2021, 10:40 pm
High-end Varnish-tuning. Tuning the Varnish HTTP cache to serve 27K requests/second on a single core 2.2GHz Opteron. # 20th October 2009, 9:25 am
ETags And Modification Times In Django. Part of Malcolm’s series of tutorials on implementing advanced HTTP concepts in Django. # 13th December 2008, 9:49 am
HTTP Cache Channels (via) Interesting extension to the HTTP caching model by Mark Nottingham: caches can be told to subscribe to an Atom feed which alerts them to cached data that has gone stale. Group invalidation is also supported. # 4th January 2008, 12:48 pm
Two HTTP Caching Extensions. stale-while-revalidate serves cached content even while a refresh has been triggered and is currently being pulled in to the cache; stale-if-error serves cached content if a service has gone down. # 12th December 2007, 11:23 am
The State of Proxy Caching. If you’ve always wondered exactly what intermediate proxies are going to do to your carefully constructed Web application, here’s your answer. # 21st June 2007, 2:18 pm