Cache timing allocation for transformed images

In i3, our image management solution, setting the max-age and s-maxage values in the Cache-Control header is done through two custom headers: TCDN-i3-max-age and TCDN-i3-s-maxage, both with the same semantics.

For example, if we wanted to serve images on our domain in WebP format with a max-age of one minute (60 s) and an s-maxage of one month (2592000 s), we would simply need to deploy a VCL configuration similar to the following from the dashboard:

i3 - Cache-Control
sub vcl_recv {
    if ( == "") {
        set req.http.TCDN-i3-transform = "auto_webp";
        set req.http.TCDN-i3-max-age = "60";
        set req.http.TCDN-i3-s-maxage = "2592000";

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