/ipfs/cid can return different bytes based on Accept header which caused bugs in the past (block response being returned instead of deserialized one etc)
We can't use Vary: Accept because we don't want cache key to be different for every blient/browser, we only want it to be different for block/car/ipns-record/tar/(dag-)json|cbor content types
Solution
Old bifrost-infra had custom code that uses custom cache key if response is block or car
Generic HTTP stack like LB from Cloudflare may not have that capability, and if it does, it requires custom config similar to one we did in Nginx.
Better to solve this at gateway level, using generic HTTP, with safe defaults that "just work" with stock HTTP tools and services, without requiring additional config on each deployment
Ideas
(A) Ensure unique URL per response type, so it does not matter if HTTP middleware is not aware of our content-types
Return HTTP 302 to ?format=car|raw|foo with Cache-Control: no-cache when alternative response format is requested
DOWNSIDE: bypasses http caches, hits backend every time (path needs to be resolved, blocks fetched/read)
Problem
/ipfs/cidcan return different bytes based onAcceptheader which caused bugs in the past (block response being returned instead of deserialized one etc)Vary: Acceptbecause we don't want cache key to be different for every blient/browser, we only want it to be different for block/car/ipns-record/tar/(dag-)json|cbor content typesSolution
Ideas
?format=car|raw|foowithCache-Control: no-cachewhen alternative response format is requestedContent-Location: [...]?format=foowith non-default responseVary: Acceptand pay the penalty of more cache missesPlan