I’ve been trying to understand the general CDN caching story around Ghost. For some hosted Ghost installs I noticed that the max-age is quite high, and was concerned that this may cause stale pageloads. However, I see in the sourcecode that there are large amounts of X-Cache-Invalidate header usage, presumably to invalidate previously cached pages. However, I’m unsure about how that header is being used. Is it some middleware that handles it that I’m missing? I know that something must intercept that header value and process it, but I’m unsure if that is the CDN itself or some Express middleware that is optionally configured that calls out to the CDN host to invalidate.
I’ve searched on Google for the string “X-Cache-Invalidate” but could not find any documentation on this header, it does not seem very common.