Cache-Control and Expires
When setting up a localhost caching reverse proxy I noticed that libravatar.org doesn't set the Cache-Control (and Expires) header.
Gravatar sets
Cache-Control: max-age=300Should libravatar use something similar?
The libravatar API only mentioned caching in relation to SRV records (1 day = 24 hour?). Should avatars itself be allowed to be cached for 24 hours?
In @tastytea's libravatarserv example config for nginx the Expires and Cache-Control are set to 86400 (24 hours) (+ Cache-Control adds public):
Since the libravatar api very much rely on query string it's affected by https://httpd.apache.org/docs/trunk/caching.html#http-caching, under "What Can be Cached?":
If the URL included a query string (e.g. from a HTML form GET method) it will not be cached unless the response specifies an explicit expiration by including an "Expires:" header or the max-age or s-maxage directive of the "Cache-Control:" header, as per RFC2616 sections 13.9 and 13.2.1.
I suppose this might affect caching in clients? I haven't checked that.
Using mod_expires I used something like:
ExpiresActive On
ExpiresDefault "A86400"
Header merge "Cache-Control" "public"(Maybe
ExpiresDefault "access plus 24 hours"`is a bit more readable.)