Hi team -

There was a question yesterday if we had caching headers in the APIs consumed by the apps.

I did a quick cURL on a couple URLs for Android and iOS and it seems like maybe requests are served cold from the Varnish cache (as with many API responses), even if there may be some memcached/Redis hot storage at the web server for the underlying content.

Does anyone know if there's a safe approach to implement caching headers (e.g., Cache-Control, Expires, ETag, etc.) to optimize for hot cache hits for the API endpoints used by the apps and experimental webapps? In particular, would we benefit from doing so on action=mobileview? Is there a way to canonicalize the request parameters to increase the odds of a cache hit regardless of whether iOS or Android made the first hit (either client-side or perhaps at the edge with scare VCL)? What about for other API endpoints?

-Adam

$ curl -s -D - "http://en.m.wikipedia.org/w/api.php?action=mobileview&format=json&page=Fish&prop=text%7Csections%7Cthumb%7Cimage%7Cid%7Crevision%7Cdescription%7Clastmodified%7Cnormalizedtitle%7Cdisplaytitle%7Cprotection%7Ceditable&onlyrequestedsections=1&sections=0&sectionprop=toclevel%7Cline%7Canchor&noheadings=true&thumbsize=640" -o /dev/null | grep -v GeoIP

HTTP/1.1 200 OK

Server: Apache

X-Powered-By: HHVM/3.6.1

X-Content-Type-Options: nosniff

X-Frame-Options: SAMEORIGIN

Vary: Accept-Encoding,X-Forwarded-Proto,Cookie

Content-Type: application/json; charset=utf-8

X-Varnish: 2886917462, 1761146385

Via: 1.1 varnish, 1.1 varnish

Transfer-Encoding: chunked

Date: Wed, 03 Jun 2015 13:20:08 GMT

Age: 0

Connection: keep-alive

X-Cache: cp1046 miss (0), cp1046 frontend miss (0)

Set-Cookie: WMF-Last-Access=03-Jun-2015;Path=/;HttpOnly;Expires=Sun, 05 Jul 2015 12:00:00 GMT

Cache-Control: private, s-maxage=0, max-age=0, must-revalidate

$ curl -s -D - "https://en.m.wikipedia.org/w/api.php?action=mobileview&format=json&noheadings=true&page=SM%20U-66&prop=sections%7Ctext%7Clastmodified%7Clastmodifiedby%7Clanguagecount%7Cid%7Cprotection%7Ceditable%7Cdisplaytitle%7Cthumb%7Cdescription%7Cimage&sectionprop=toclevel%7Cline%7Canchor%7Clevel%7Cnumber%7Cfromtitle%7Cindex&sections=all&thumbwidth=640" -o /dev/null | grep -v GeoIP